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Modeller Reference Manual

1. cccssseccesseecesseeceeseesenseesenseesenseesenneesones 170 Drucker Prager MOdel G4 nirani witli i aaa nescence haaa 171 Multi Crack Concrete Model 94 cccsscseesceesseeseeenseeeceesseeeeeanseeseoeseeeeoaaseessonsaeessoannees 172 Stress Resultant Model 29 vicsecios ieee sshd ccenGiiyiccacshd cecaccevicdensde ands cacy ic cuatesuacuacawiagassssancescevinenss 176 ET o ee a re ne ee ee se eer ene ee eee enna errr p re ene reer ee 176 DEAN AGG wares cane E ccd end E cance na cde cz da E E anda E E EA E E N 177 VISCO ASU Cates EE cca una oan arate ieee mrcape Oty 178 Shrinkage PFO Peles ororena aiaa EK itv aA EEEa ANKA 179 TWO Phase riie ooa aa ei aa aaa ae a a aaa a aa a a ia eaa aaa 179 PRUID DEP ieioea oe aerae a eee ae e Eae a E aE 179 Volumetric Crushing Model 81 cccccescssssseeeeeseeeeesseeeesseeneaseeeeeseoaenseeeeeseeoeneeeesseaes 182 Generic Polymer with Damage Model 89 ccccceeeeeeeeeeeeeeeeeeenseeeeeeeneenseeeeeseeeenseeeees 184 Concrete Creep and Shrinkage CEB FIP Model 86 cccccccceesssessssseeeeeeeeeeeeeeeeeeennnns 184 Elasto Plastic Interface Model 26 27 cc sscccssseeceeseecenseecenseesenseesenseesenseesoaseesenseesones 185 Delamination Interface Model 25 c ccsssseecesseecenseeseneeesenseeceaseesoaseesonsessonseesonsessones 185 Massaa eater cdc achat a e awe ace ua aia e a EIE aae aa aaea 186 Resultant USER oireina aaa ee os aie ae dee erat
2. Oivwisions 4 divslz TN a j Orientation Axes Orientation axes may be viewed as a local axis set for Lines Surfaces and Volumes The local x y and z axes are shown with a double arrowhead on the x axis and a single arrowhead on the y axis and no arrow head on the z axis When features are meshed the orientation of the feature determines the orientation and spacing of the elements Therefore the orientation of Lines Surfaces and Volumes can be changed by reversing or cycling the features See Changing Geometry Orientation for more details In all of the following illustrations the local axes are orthogonal L Line directions can be drawn to indicate the local x direction of Line or axes can be displayed L1 Local x Axis 13 Modeller Reference Manual LI Surface axes or surface normals can be displayed Axes are positioned adjacent to the first Line in the Surface definition In the example shown the axes are orthogonal but viewed from an angle to show the z axis Orientation LJ Volume axes can be displayed The origin or the axis is closest to the first point in the first Surface of the Volume definition y Axis La Local z axis Surface normal Local y Axis Local x Axis Local z axis Local Local x Axis Tip To aid axes visualisation on larger models choose the Orientations only if selected option This will display axes only on selected features Labels Labels can b
3. Surface 1 Lines 2 1 2 3 4 Meh Aegular Plane Stress Gimp Thickness 15 Browse Selection Mat Mild Steel Ungraded H mm t s 0 a Browse Csaslable Items There are 3 items at this position Press Tab to cycle through them Browse Selection Memory Browse Visible ltem Next Previous Closest Furthest 12 253 Y 322875 Z N A Selected Surface 1 3 teme cyclable 2 The currently selected feature is also displayed in this area of the Status Bar A right click here displays a context menu allowing even greater control over the selection of items Even closer control over the selection of items at the same cursor location can be attained using the Browse Cyclable Items window which is available on the right click in the status bar or from the View gt Browse Cyclable Items menu Associate Selection Downwards ih Associate selection downwards is an option to automatically select lower order features when selecting objects in the model For example selecting a Surface will also select the Lines and Points that define the Surface This option may be invoked from the Edit gt Associate Selection Downwards menu item Associate selection downwards is set off by default Associate Operations Downwards E Associate Operations downwards is a option to operate on lower order features when a command is issued For example deleting a Surface will also delete the Lines and Points which define that Surface
4. Z key Note If any part of the model is selected it is used as the centre of the zoom Zoom ke Drag a box around the region to be enlarged or click the left mouse button to zoom in progressively with each click Ctrl key Zoom out when held at same time Note The cursor position dictates the centre of the zoom Orthogonal Model Views These buttons are located in the status bar NAA View along the X axis towards the origin Y N A View along the Y axis towards the origin Z N A View along the Z axis towards the origin Any of the views along these axes can be modified by using these key sequences which select an alternative view orientation Shift key Nd View along the X axis towards the origin Ctrl key Y N A View along the Y axis towards the origin Ctrl Shift key lt N A View along the Z axis towards the origin Equivalent toolbar buttons for these view shortcuts can be found on the customisable toolbar dialog or by clicking the right mouse button on the orthogonal model view buttons Non Orthogonal Model Views BY isomeric v Isometric view ch a Ctrl key Reverse isometric view e Dimetric view Ctrl key e Reverse dimetric view 412 Appendix C ei Trimetric view Ctrl key B Reverse trimetric view Useful Windows Shortcuts The following standard Windows shortcuts are useful when creating and printing models in LUSAS Modeller Ctrl key N ke
5. BB SHB lower HA KEL upper and minimum values from a numberof b fh 12 Design Combination Max results loadcases combinations or other o 13 Design Combination Min a ae 10 Live Load Envelope Max envelopes When an envelope has been AD 11 Live Load Envelope Min defined a pair of loadcases are created Jou Fi Combination and envelope options containing the maximum and minimum z envelope values Defining a Combination or Envelope The Utilities menu is used to add a new combination or envelope Combinations or envelopes may be defined at either the modelling stage prior to analysis or at the results processing stage Once defined combinations and envelopes are treated as loadcases and are listed in the Loadcase Treeview Their properties may be edited by double clicking on the entry in the Treeview When the first load combination or envelope is added to the Treeview a Combination and envelope options object is also created Double clicking on this object displays a dialog on which results components can be selected for calculating and saving in the Modeller results file When results components are selected prior to an analysis being carried out the results for the primary components chosen will be available for results processing immediately after the results file is loaded because results for these components will have been automatically saved cached in the Modeller results file When results comp
6. Geometry can be defined by entering coordinates selecting Points on the screen by using utilities such as transformations or by importing it from a CAD system Attributes are first defined and then assigned to selected features To complete a model it may be necessary to define analysis control data This is used to control the progress of an advanced analysis Running the Analysis Once a model has been created click on the solve button to begin the analysis LUSAS creates a data file from the model solves the stiffness matrix and produces a results file The results file will contains some or all of the following data Chapter 1 LI Stresses LJ Reactions Q Strain energy LI Strains LJ Yield flags Q Displacements 0 Potentials LI Velocities LJ Fluxes LI Accelerations Q Gradients Q Residuals LJ Named variables Viewing the Results This involves using a selection of tools for viewing the results file produced from the analysis Many different ways of viewing results are supported LI Undeformed Deformed Mesh Plots LI Contours Averaged and Unaveraged L Vectors Q Diagrams Bending Moments and Forces LI Animated Display of Modes Load Increments LJ Sections Lines and Slices LI Yield Flag Display Q Graphing Q Printed Output What Help and Documentation is Provided Comprehensive documentation is provided with LUSAS Some is available in the form of printed manuals whilst some is only available in electronic for
7. Loadcase 1 Title Loadcase 1 Line 1 RSLT THE 0 0 0 0 0 0 0 0 29 S929E 6 6 5848E 6 30 3167E 6 92 5111E 6 an oaouwn 9 i 2 10 ode DX DY RSLT THE 12 0 445019E 18 0 263404E 3 0 263404E 3 28 9669E 21 13 0 445298E 18 0 261587E 3 0 261587E 3 31 7524E 21 14 15 i 5 16 ode DX DY RSLT THE 29 5929E 6 6 5848E 6 30 3167E 6 92 5111E 6 13 7034E 6 O 705137E 3 0 70527E 3 0 224658E 3 6 DX DY RSLT THE 13 7034E 6 0 705137E 3 0 70527E 3 0 224658E 3 0 445019E 18 0 263404E 3 0 263404E 3 28 9669E 21 Notes e Not all sections of a report can be selected to make a sub report The cursor will change to a magnifying glass when it is over data that can be selected for a sub report e The toolbar buttons such as Export Report Print Report etc act on the currently selected preview tab and hence the currently selected report view This means that only those pages in the particular report or sub report that is being viewed will be exported or printed _ e To delete the visible sub report select the Close Current View button at the top right of the report viewer toolbar Exporting Report Data When viewing a report report data may be exported to a variety of formats to any of the following destinations by use of the Export Report button ae LI To an Application on your computer that will open once the file has been created LI To a file on your disk Disk file Q To a folder in your mail client Exchange
8. Q Shrinkage Used to define the shrinkage properties of a material as a piecewise linear curve LI Viscosity Used to model viscoelastic behaviour Coupling of the viscoelastic with nonlinear elasto plastic materials enables hysteresis effects to be modelled LI Two phase Required when performing an analysis in which two phase elements are used to define the drained and undrained state for soil Plastic Material Models sotropic The following are Isotropic models available from the Attributes gt Material gt Isotropic menu item by choosing the Plastic check box on the material attribute dialog LI Stress Potential von Mises Nonlinear material properties applicable to a general multi axial stress state requiring the specification of yield stresses in each direction of the stress space Incorporates hardening yield stress and heat fraction The modified von Mises model allows pressure dependent plasticity to be defined Q Optimised von Mises Model 75 Represents ductile behaviour of materials which exhibit little volumetric strain for example metals Especially for explicit dynamics LI Tresca Model 61 Represents ductile behaviour of materials which exhibit little volumetric strain for example metals Incorporates isotropic hardening Q Mohr Coulomb Model 65 The non associated Mohr Coulomb model represents dilatant frictional materials which exhibit increasing shear strength with increasing confining stress for example gra
9. Transformations Transformations are used in two ways LJ When moving copying or sweeping geometry a transformation is specified and may be saved if required Q For special applications such as to orient discrete point and patch loads or to define a reflective mirror plane for thermal analyses Transformation attributes are defined using the Utilities gt Transformation menu item as well as from a move copy or sweep dialog Certain transformations can be defined by adding two or three geometric Points to selection memory before initiating the transformation command The following transformation types are available Q Translation Linear translation along a specified vector coordinate The vector coordinate will use the active t pF coordinate set Two Points added to Y selection memory can be used to Y P1 Y define the vector coordinates In this X A pe example the translation is defined using Points 1 and 2 which stores a translation of X and Y This is then used to copy the Surface shown 100 Chapter 4 L Rotation in a global plane A specified angular rotation in either the XY YZ or ZX global plane at a specified origin In this example Surface 1 is copied about the global origin through positive 90 degrees A right hand corkscrew rule is used for rotations Local coordinate systems can be used to rotate about non global axes Q Mirror A mirror plane may be defined by specifying thre
10. whether Averaged nodel Gauss Point or Element Nodal results should be Cancel Hep calculated Q The Summary checkbox chooses whether or not to display a summary for each results component chosen This summary consists of the maximum and minimum values encountered along with their location Note that sub reports cannot be created from Summary results information when listed in a report Q The Tabular results checkbox chooses whether or not to display a table of numerical results If chosen a value will be written to the report for each component for each loadcase for each node or gauss point chosen Such tables can be very large Note that sub reports can be created from Tabular results information when listed in a report Q Additionally Nodal coordinates can be added to the report These take the form of additional columns of data in the tabular results one each for the X Y and Z coordinates of each node LI The number of Significant figures or Decimal places can be specified for values written to the report for this chapter 378 Chapter 8 Add or Edit a Loadcase Results Chapter Model properties Loadcase Basic combination results User content Edit Delete Order by Loadcase Feature Loadcases fa Chapter name Report on Ful model OK Cancel Help The Loadcase Basic Combination results tab of the Chapters dialog is only shown if a results file is loaded The En
11. Chapter 8 Loadecase 1 Loadcase 1 Results file tubular_roof_frame mys Fibre R2 Cross Section Line Geometric 2 Entity Stress Thick 3D Beam Component SxfFx hiy Mz 6 5655E6 4 92412E6 3 28275E6 1 64137E6 0 465661E 9 1 64137 E6 3 28275E6 4 92412E6 6 5655E6 Maximum 7 97335E6 at as point 1 of element 11 Minimum 6 79901E6 at Gauss point 11 of element9 x Z Line contours plotted at top beam fibre location Loadease 1 Loadcase 1 Results tile tubularroof_ftrame mys Fibre R4 Cross Section Line Geometric Entity Stress Thick 30 Beam Component Sfx hiy biz 6 6375E6 4 978 15E65 3 31875E6 1 65935 E O 465661E 9 394E3 1 65938E6 A ST SOGEB B 31575E5 4 078 1365 6 6375E5 Maximum amp 88407E6 at Gauss point 11 of element 14 Minimum 3 050341E6 at Gauss point 1 of element 9 x fa Line contours and diagram stress results plotted at bottom beam fibre location 357 Modeller Reference Manual Fibre locations When plotting selected contour or diagram results oie amp S l IB for beams a fibre location must be used to specify El frame_2d mdl the place s on the beam section at which the de a results should be calculated and plotted Results for MEd Geometic 3 individual fibres are plotted by setting that fibre o i eee E EEEE location active for a particular geometric line SERS o attribute in the b Treeview The active fibre is Pb dG denoted
12. D Loadcase 1 RSLT 0 0 30 3167E 6 0_263404E 3 0 261587E 3 0 70527E 3 0 716351E 3 0 0 30 3167E 6 0 70527E 3 0 716351E 3 2 SLUES 0 224650K 5 022511563 Sub report listing ordered by Loadcase Mesh TH il 0 92 5111E 6 28 9669E 21 31 7524E 21 0 224658E 3 0 225115E 3 T O 99 5111E 6 0 224658E 3 0 225115E 3 Chapter 8 Sub report data exported to a Microsoft Excel spreadsheet Exporting Report Data to a Word Document When viewing a report report data may be exported to a Word Document by use of the Export Report button E This will require you to LI Select a Format of Microsoft Word Editable RTF LI Select a Destination of Application LI Select a page range Note that the Results chapter Order by option which dictates the order in which the tabular results sub headers are written is particular use when exporting results data If you do not wish to group the results per feature e g per line which is the default then the option to order by Loadcase Mesh should be used This Order by option should be set prior to exporting the data as follows 1 Inthe Report Treeview select the Results Chapter name and use its context menu to the select Modify menu item which in turn will display the Edit Chapter dialog 2 Use the Order by drop down to select the Order required e g Loadcase Mesh and click OK 387 Modeller Reference Manual 3 Inthe Report Tre
13. LI New data points may be added by adding new rows to the grid either by using Insert Row from the Edit menu or by pressing the Tab key when the cursor is in the final cell Q Data points may be deleted by deleting the data in the grid LI Blocks of data from a spreadsheet may be pasted New rows will be added to the grid as necessary Note These changes are made to the graph only and are not stored in the corresponding graph dataset Pasting Graph Data To Spreadsheets ES To paste graph data to a spreadsheet use Copy from the Edit menu when the data has been highlighted in the graph data table then paste into the spreadsheet come Hotate 49 LIockwite It is also possible to export selected or all ey graph datasets to a csv file by using the cog 1 Coordi Delete all context menu for the Graph entry or ff 2 5E 11 Export all graph dataset name in the Utilities n af 3 Coordi treeview Columns of data are created ai AD 4 Visible with graph dataset names being written to Invisible row one of each column Printing Graphs Graphs may be printed using the File gt Print command Because graphs are created as separate windows a single graph will be printed on each page To print multiple graphs together use Copy from the Edit menu when the graph area is active then paste into a suitable word processor 367 Modeller Reference Manual Case Study Plotting Families Of Curves To compare r
14. background grid 131 backup 50 basic combination 327 beam cross section 148 beam loads 199 beam stress recovery 358 beam stresses 355 bending moment diagrams 344 BFP loading 195 birth and death 223 BMP 375 boolean geometry 97 boundary discretisation 129 Browsing Selected Features 411 buckling analysis 292 298 C CAD 114 Canada steel sections 152 case studies 44 45 114 127 geometry 114 meshing 127 CBF loading 195 217 Modeller Reference Manual centripetal stiffening 296 China steel sections 153 Cholesky solver 309 CL loading 195 196 217 combinations 324 389 combined line 69 82 command bar 9 command files 54 command line 9 composite analysis 241 334 Composite Damage Model 177 Composite layup defining 243 definition methods 241 visualisation 245 Composite model data visualisation 247 concentrated load 195 concrete heat of hydration 164 concrete material model 164 172 352 conduction 227 conjugate gradient solver 309 constant body force 195 constraint equations 230 contact 227 234 contouring 118 343 convection 227 coordinate system 248 copying geometry 99 coupled analysis 302 crack patterns 352 creep 165 176 184 291 Cross section 148 crushing material model 182 crystal reports 382 cursor 75 77 85 selection tool 29 474 customise startup templates 44 Cuthill McKee optimiser 309 cycling geometric feat
15. 20 0 5 in the Final Z temperature gradient field e The initial slab mid surface temperature of 20 is entered in the Initial temperature field When the analysis is run LUSAS will multiply the temperature gradient by the thermal coefficient of expansion specified in the material property attribute to calculate the thermal bending strain This method assumes a linear temperature distribution through the depth of the slab If a known nonlinear variation is required solid elements must be used with a variation defining the nonlinear through thickness behaviour Stress and Strain SSI SSR The input values that are required in order to define stress and strain loading for particular elements can be seen by selecting the either the element description or by entering the element name in the Stress and Strain loading dialog Q Initial defines an element initial stress strain state in local directions Initial stresses and strains are applied as the first loadcase and subsequently included into the incremental solution scheme for nonlinear problems Initial stresses and strains are only applicable to numerically integrated elements LI Residual defines element residual stress levels in local directions This can only be done for elements with a nonlinear capability Residual stresses unlike initial 198 Chapter 6 stresses are assumed to be in equilibrium with the undeformed geometry and are not treated as a loadcase as such They are con
16. 38 Chapter 2 2 Clicking on part of the model will zoom in progressively for each click Hold the Control key to zoom out amp Dynamic Zoom is similar to dynamic rotate Using the cursor the model can be visually enlarged or reduced in size Panning Dragging the Model su Dynamic Pan allows the model to be dragged into position on the screen Reseting the View tl Home Restores the view to a scaled to fit view in the XY plane ts Resize When the resize button is depressed the model will fit into the available screen area See Appendix C Model Viewing Shortcuts for a complete listing of all model viewing facilities and keyboard shortcuts available Undo Redo a 2f The Undo button allows any number of actions since the last save to be undone If more than the last action is to be undone then the actions to be undone may be selected from the undo history list by clicking on the down arrow at the side of the undo button ma Se Redo is available immediately after choosing an undo event to enable the undone action to be reinstated Notes e The undo facility works by replaying the session file from the last save Because of this it is advisable to save the model frequently to speed up the undo facility e Undo is only available when a model file is loaded i e undo is not available when a results file is loaded without a corresponding model file Page Layout Mode Two viewing modes are available both accessed fr
17. In each case the number of pages to be opened or saved can be specified Note that when saving to disk the default export directory is a temporary directory specified by the report creation software that is used Browse to your LUSAS project directory to save your report file with your model if required When the number of columns in a report become too large for a portrait view use Page Setup accessed from the Report Name context menu to either change the report page margins or to change the report page orientation to Landscape 385 Modeller Reference Manual Exporting Report Data to a Spreadsheet When viewing a report report data may be exported to a spreadsheet such as Excel by use of the Export Report button LI Select a Format of Microsoft Excel 97 2000 Data only XLS LI Select a Destination of Application LI Select Custom format options Note that use of the Results chapter Order by option to dictate the order in which the tabular results sub headers are presented is of particular importance when outputting results data to a spreadsheet The option to order results data according to Loadcase Mesh is recommended because of the reduced number of blank lines it creates in the output file The images that follow show an example of a sub report created with Loadcase Mesh order and the corresponding results exported to an MS Excel spreadsheet This Order by option should be set prior to exporting the data as follow
18. Pens are used in a number of dialogs Whenever a pen is used a Choose pen button allows access to the Pen Library to specify a different pen or to change the pen colour or style If a particular pen style or colour is changed then this will affect every operation that references that pen 26 Chapter 2 Loading a View A previously saved view may be loaded into a new window or into the current window using the Window gt Load View menu item Any of the saved view settings can be chosen Copying Windows A window can be copied by selecting and copying the window name in the EE Treeview then pasting the window back into the EE Treeview The window layers and settings are also copied Using Layers Model information is held in separate pre named layers to aid selective viewing of both model and results data Layers can be added or removed from a view window by right clicking on a blank part of the graphics area or by right clicking the window name in the Treeview and selecting Properties from the context menu or by selecting the View gt Insert Layer menu item The display of layers in the current window can be turned on or off by right clicking on the layer name in the Er Treeview and selecting deselecting the On Off option Turning a layer off retains the layer in the Layers E Treeview but removes the display of that layer from the Graphics Area Layer symbols explained A symbol adjacent to each layer name in the Layers Er
19. Q Heat fraction The fraction of plastic work that is converted into heat energy Only applicable to temperature dependent materials and coupled analyses where the heat produced due to the rate of generation of plastic work is of interest The value should be between 0 and 1 LI Slope of Yield Stress The slope of the uniaxial yield stress against equivalent plastic strain Q Plastic strain The limit of equivalent plastic strain up to which the hardening curve is valid 171 Modeller Reference Manual Cohesion o tan C1 1 Equivalent Plastic Strain Cohesion Definition for the Drucker Prager Yield Model Model 64 Friction Angle tan C2 L Equivalent Plastic Strain p Friction Angle Definition for the Drucker Prager Yield Model Model 64 Multi Crack Concrete Model 94 The multi crack concrete model is a plastic damage contact model in which damage planes form according to a principal stress criterion and then develop as embedded rough contact planes The basic softening curve used in the model may be controlled via a fixed softening curve or a fracture energy controlled softening curve that depends on the element size The former a distributed fracture model is applicable to reinforced concrete applications while the latter localised fracture model is applicable to un reinforced cases Material Properties Q Uniaxial compressive strength f e g 40 N mm Q Uniaxial tensile strength f
20. Se ih 00x ieee E Preview Report Viewer Toolbar Buttons E Export Report permits reports or sub reports to be exported to a variety of formats to any of the following destinations 382 Chapter 8 e Toa file on your disk Disk file e To an Application on your computer that will open once the file has been created e Toa folder in your mail client Exchange Print Report prints the current report or sub report view only to a specified printer Toggle Group Tree permits the viewing of loadcase feature numbers in sub reports in a treeview style format 1 316 aes Page selection These options provide the means of moving or jumping to a specific page x Stop Loading stops the loading of large files S Refresh refreshes the view contents K Search Text provides the means to find and jump to particular words in the report or sub report rA l Lo adjusts the size of the page view x Close Current View closes the sub report view leaving other views visible until they are closed To go back to the LUSAS Modeller window the report viewer must be closed by using the report window s main Close button Notes e When viewing a report using the Crystal Reports viewer no changes can be made in LUSAS Modeller The only way a LUSAS model or the report listing as held in the LUSAS Report Treeview can be re edited is to close the report view This is to ensure that the report data always matches the model fro
21. Smart combination Max 45 Smart combination Min will assemble results from the loadcases using just the permanent factors given for positive load effects and using permanent variable factors for negative load effects Factor used for Nodal Permanent Variable maximum Factored nodal Loadcase result factor factor combination results Dead load 20 1 0 0 15 1 0 0 15 20 x 1 15 23 Deck surfacing 10 1 0 0 75 1 0 0 75 10 x 1 75 17 5 Superimposed load 15 1 0 0 2 1 0 0 2 15 x 1 20 18 Smart combination Min 58 5 Smart Combination Case 2 Consider a node where short term load effects are of mixed sign In this instance the permanent and variable load factors are considered and will be added together based on the nodal result being adverse However as the permanent effects have been set to zero this will only combine the results that are adverse Smart combination Max will assemble results from the loadcases using just the permanent factors given for negative load effects and using permanent variable factors for positive load effects 390 Appendix A Factor used for Nodal Permanent Variable maximum Factored nodal Loadcase result factor factor combination results Temperature 5 0 1 3 0 5x0 0 Wind 5 0 1 4 0 5x0 0 Settlement 10 0 1 2 0 10x0 0 Live load 1 20 0 1 5 0 20x0 0 Live load2 15 0 1 5 0 15x0 0 Live load3 10 0 1 5 0 1 5 10x 1 5 15 Live load 4 5 0 1 5 0 5x0 0 Smart combination Max 15
22. Smart combination Min will assemble results from the loadcases using just the permanent factors given for positive load effects and using permanent variable factors for negative load effects Factor used for Nodal Permanent Variable maximum Factored nodal Loadcase result factor factor combination results Temperature 5 0 1 3 0 1 3 5 x 1 3 6 5 Wind 5 0 1 4 0 1 4 5 x 1 4 7 Settlement 10 0 1 2 0 1 2 10 x 1 2 12 Live load 1 20 0 1 5 0 1 5 20 x 1 5 30 Live load2 15 0 1 5 0 1 5 15 x 1 5 22 5 Live load3 10 0 1 5 0 10x0 0 Live load 4 5 0 1 5 0 1 5 5x1 5 5 Smart combination Min 83 Within the smart combination facility there are also two check boxes marked Loadcases to consider and Variable loadcases These additional options are used for a number of bridge design codes that require the loadcases in the combination to be filtered Smart Combination Case 3 Consider a node where short term load effects are of mixed sign with the Loadcases to consider set to four 391 Modeller Reference Manual In this instance the permanent and variable load factors are considered and will be added together based on the nodal result being adverse With the number of Loadcases to consider set to four only the four most positive resultants will be combined for the Max combination and the four most negative resultants will be combined for the Min combination 9 Smart combination Max will assemble
23. Surface local coordinates can not be set active Defining Local Coordinates Local coordinates are defined from the Attributes gt Local Coordinate menu item by specifying the local coordinate type and for Cartesian cylindrical and spherical types an origin and either a rotation about a global plane or a rotation matrix Note Defining a new coordinate set does not automatically make it the active set see Using Local Coordinates below LI Rotation about a global plane specifying angular rotations about the global planes XY YZ or XZ When defining coordinate systems using this method the local x axis is oriented parallel to the global X axis and rotated into position using the specified angle in the specified plane Q Rotation matrix specifying a direction cosine matrix A Rotation matrix may be defined from selected Points by first selecting 3 Points 1st Point defines the origin 2nd Point defines the positive direction of the local x axis 3rd Point defines the local xy plane and clicking the Use button Notes e Local coordinate set types cannot be modified E g a Cartesian sets can not be changed to a cylindrical or spherical set e Local cylindrical coordinates defined by matrix are always defined with the local z axis along the cylinder Visualising Local Coordinates The active local coordinate system is defined from the Model Properties Geometry tab or from the local coordinate attribute context menu using the Set Acti
24. When an applied force changes direction during an analysis to match the deformed shape of the model Also known as follower force non orthogonal cracking Formation of a second subsequent crack which is not normal to the first crack direction That is a cracking formulation which allows re computation of the principal stress directions following an initial cracked direction formation See also cracking concrete model ductile fracture orthogonal cracking non planar Not lying in a flat plane See planar nonlinear A term encompassing all effects that do not have a basis in linear stress analysis For example geometric and material nonlinear effects and nonlinear boundary conditions nonlinear elasticity A material which follows a nonlinear i e not straight path on loading but exhibits complete recovery on unloading norm A measure used in convergence See convergence normalisation A process where the maximum displacement of an eigenvalue analysis is expressed relative to unity or to the total mass of the problem null A line mesh containing no elements which is used purely to define mesh spacing is termed a null mesh A null slideline type allows definition of a slideline in a problem which introduces no contact effects Slideline 451 Modeller Reference Manual types can be changed during an analysis so contact can be introduced at a specified point by changing the slide type numerically integrated beam A be
25. e g conjugate gradient solvers are usually only applicable to static linear analyses and will perform best on large well conditioned problems since the time taken for solution is less dependent on the size of the problem than for direct solvers Iterative solvers require far less storage memory disk space than direct solvers This means that iterative solvers sometimes have the advantage of remaining in memory where a direct solver would have to run out of memory Iterative solvers are only applicable for a single loadcase 309 Modeller Reference Manual Support for specification of various solver types is available within LUSAS Modeller The current solver options supported are as follows LJ Direct Frontal selects a direct sparse solution technique based on Gaussian elimination Stiffness and load arrays are read into memory and assembled into the structural stiffness matrix and load vector There is a choice of two direct solvers Standard Frontal an element by element frontal solver which does not require assembly of the global stiffness matrix This solver is applicable to all types of analysis present in LUSAS Solver Fast Multi Frontal a global frontal solver which assembles global stiffness and load data This solver is applicable to all analysis types except for superelements Guyan reduction and non linear problems involving branching and bracketing LI Iterative Conjugate Gradient selects an iterative sparse s
26. 2 specified coordinates indicates a straight line load 3 specified coordinates indicates a curved line load 4 specified coordinates indicates a straight sided quadrilateral 8 specified coordinates indicates a curved sided quadrilateral The following examples show patch loads assigned to Point 1 Once assigned the load origin is located at Point 1 Example 1 Example 2 A straight line load defined using 2 coordinates A curved line load is defined using 3 coordinates Example 3 Example 4 A straight sided quadrilateral defined using 4 A curved sided quadrilateral defined using 8 coordinates coordinates 203 Modeller Reference Manual Note that the mid side nodes for a curved line load and for a curved sided quadrilateral load must lie with 10 of the overall distance between the corner nodes Compound load Compound loads may be created to simplify the definition and assignment of more complex loads Compound loads form a set or load train of previously defined discrete loads that are subsequently assigned to a model as one loading A compound discrete load may be defined from any combination of existing point patch and compound discrete loads For example a patch load representing a truck may be included in a compound load twice and by specifying the distance between the trucks a simple load train is created Additionally the same load may also be used any number of times to define the same compound load x y z offse
27. A loadcase icon changes from being greyed out to coloured when made the loadcase is set active When modelling the active loadcase is denoted by a coloured loading icon When results are loaded the active loadcase is denoted by a coloured contoured results icon Viewing the Assignments in a Loadcase Loadcase dependent attribute assignment are displayed in the Treeview under the loadcase to which they have been assigned The geometry to which an attribute has been assigned may be selected by picking Select Assignments from the context menu in the Treeview The attribute may be visualised for the active loadcase from the context menu using the Visualise Assignments item Note Within a linear analysis with the exception of loading attributes assigned to the first loadcase apply to all loadcases in the analysis For nonlinear and transient analysis many attributes may be modified as the analysis progresses An attribute assigned in a loadcase will remain active until it is changed This means a support assigned in the first loadcase will apply to all loadcases unless it is set free in a subsequent loadcase Load Combinations or Envelopes Combinations and envelopes can be defined as part of the modelling process prior to carrying out an analysis or after carrying out an analysis For more details see Combinations and Envelopes in the Viewing the Results section Load Curves Load curves can be used to describe the variation of the
28. Fosce Moment Thick Plate Arrotaton Visualising The Results 10 0 20 0 26 0 ET E D 4 Properties x Cortout Results Contou Display Contour Range Sead Colors Entity Force Moment Thick Plate ot TT road 1 lapccace 1 Set Visight TI Resuks fe deck mys rtty Force errere Theck Pie Component Usagem cma aw Hee Results visualisation is performed using results layers in the LE Treeview Each method of viewing results described below involves adding a layer to the current window The properties of the results layers may then be set to display the required results in the specified style 343 Modeller Reference Manual LI Deformed Mesh Draws the deformed mesh shape of a structure when subjected to applied load or due to mode of vibration Q Contour Display the results on the model as colour fringes or lines of equal value Q Vector Displays vector results quantities as an arrow or pair of arrows on the model LJ Values Marks result values on the model as symbols and or values Q Diagrams Displays beam element shear force and bending moment diagrams In addition to those layers listed above an Annotation layer is used to hold contour key and other annotation data that may be added to the results viewing window All results visualising will use the results from the active loadcase for the current window The active loadcase is shown with a coloured icon in the H T
29. Hoffman criterion A yield criterion catering for pressure dependent anisotropic plasticity See a so Hill criterion hour glassing An zero energy mode of deformation induced in an under integrated element See also mechanism IGES International graphical exchange system See also DXF interface files See interactive modal dynamics ill conditioning The state of the problem equations when they are numerically unstable Can be caused by vastly different stiffnesses or a badly supported structure impact An analysis where one body hits another See a so contact explicit dynamics implicit dynamics Used for inertial problems where the response is dominated by low frequency components See also explicit dynamics incompatible elements Elements using incompatible shape functions to achieve an enhanced stress resolution performance See also shape functions increment A step in a nonlinear analysis where a portion of the total load is applied Results can be obtained at each converged increment level 443 Modeller Reference Manual incremental loading Application of a loading scheme in steps or increments Used in a nonlinear analysis when full load will not converge initial stiffness method A modified Newton Raphson nonlinear solution method whereby the initial stiffness matrix is used exclusively throughout the analysis inertia A measure of the forces that would be generated in a structure under dynamic exc
30. LI Create a group of objects that failed to mesh creates a group named failedToMeshObjects which contains all features which failed to mesh Advanced meshing parameters LJ Draw failed parts of mesh only draws those parts of the mesh that failed to mesh LI Linearise element edges 20 Chapter 2 LJ Constrain adjacent linear quadratic edges forces mid side nodes on lines or surfaces to be averaged between the corner end node positions This option is turned on by default LJ Element edge collapsing invokes edge collapsing which removes elements faces with short edges and small subtended angles by merging them with neighbouring elements Attributes LI General Options Apply concentrated loads in cylindrical coordinates for Fourier elements LUSAS Solver option 202 Body force given as acceleration This option is turned on by default Turning it off converts body forces to global loads per unit volume LUSAS Solver option 48 LI Slideline Options Suppress stringent slave search For simpler geometries such as flat surfaces in contact a slight reduction in processing time may be achieved by suppressing the stringent local node search but this is not usually recommended LUSAS Solver option 184 See the Theory Manual for more details Suppress initial slide surface stiffness check Slideline stiffnesses are automatically scaled at the beginning of an analysis if the average master slave stiffnesses differ by a factor g
31. Properties 2767 108 4608 SIE m ort Ascending 261 3 108 405 0 2 Sort Descending 285 9 108 348 3 2905 108 2907 12 Design Combination Max My oO Di mS Oh 3 4 ea Save as Microsoft Excel EA aF ae Print Ctrl P 4 D gt Dei Model info 373 Modeller Reference Manual Manipulating printed loadcase results Printing results for Envelopes or Combinations When the active loadcase is an envelope or smart combination the results printed will show the primary component e g Fx marked with an asterisk Additionally for Envelopes only the loadcase in which the maximum or minimum value was extracted will be tabulated in the LCID Loadcase ID column When enveloping on All components the loadcase from which the results are extracted cannot be tabulated because each individual results component may have come from a different loadcase Ge LUSAS Yiew Averaged Forces and Moments Ea Se LUSAS Yiew Averaged Forces and Moments Bilel E Mz LCD IRES TE waa 457704 919613 oo 59092 56 6137 50 9965 20 0294 51 2462 194126 F71 6582 593 511 45 7704 50 5965 19 1477 10 4339 Cro oro oo io o o Envelope results for primary component Fx showing Envelope results for primary component All Loadcase ID No Loadcase ID can be shown Notes e Selected slice and slideline data and results may be printed from the group context men
32. Q File gt Print File gt Close The print file may be closed at any time With no print file open printed output will be directed to a text output display window Notes e Output to the text window can be directed to a log file See Text Window for more details Interface Files Interface files are used to transfer external modelling or material data into and out of LUSAS Modeller The full model or a selected portion of a model can dependent upon the file format chosen be exported to an interface file format The currently supported list of interface file formats 1s LJ CMD cmd Format for import of LUSAS Modeller model files saved as command CMD files in previous versions of LUSAS LI Solver Data Files dat LUSAS Solver data files used to import or node and element data Q DXF dxf AutoCAD Drawing eXchange Format Q IGES igs Initial Graphics Exchange Specification Format for import and export of geometry data LU LMS CADA X nf Model description and modal data exported to a file that can be read by the LMS software LI NASTRAN Bulk Data files bdf dat used to import node and element data LJ ANSYS cdb files cdb used to import node and element data LI Abaqus input files inp used to import node and element data Q PATRAN def Neutral file format for inputting phase I geometry information and outputting phase II mesh information LI STEP stp STandard for the Exchange of Product data LI STL
33. also available On import of a LUSAS Solver data file element types that are present in the datafile are used directly for the elements that are imported For datafiles other than those created by LUSAS Solver the proprietary element types that are present in the datafile are mapped to an equivalent LUSAS element based upon each element s shape and its topology If the Coupled user interface option has been selected on the New Model dialog prior to a mesh import being carried out then coupled elements will be created during the import process If a different analysis type is specified after the import of mesh data the element types previously used will be changed accordingly 16 Chapter 2 Assigning attribute data to mesh objects in mesh only models No import of any attribute data is done when element data is imported so the mesh objects the elements and their nodes edges and faces must be assigned attributes materials properties and thicknesses loading and supports prior to carrying out an analysis within LUSAS in a similar way and as documented for a feature based geometry model Rather than selecting points lines surfaces or volumes to make an attribute assignment nodes edges faces or elements are selected instead To assist in the attribute assignment process the cursor selection filter can be used to identify specific mesh objects Editing mesh only models When a mesh only model is being edited any main menu items norm
34. as an automatic data conversion will be performed based on the units in use e CEB FIP Model Code 90 is only strictly applicable to beams however in LUSAS the creep equations have been extended to 2D and 3D stress states It must be noted that it may be difficult to establish an appropriate value of nominal size for anything other than beam elements e The CEB FIP creep and shrinkage model must be run in a transient nonlinear analysis in which the time step and total response time are specified in days An option exists in the advanced time step options to use an exponent to increase the time step as the analysis progresses e The age of concrete at the time an element is introduced to the analysis may be defined using the Age attribute See the Solver Reference Manual and the Theory Manual for further details Elasto Plastic Interface Model 26 27 An elasto plastic model for representing the friction contact relationship between two discrete bodies The model is embedded in the plane membrane plane strain and solid elements to reproduce the nonlinear response of a system containing planes of weakness using Mohr Coulomb type laws See the Theory Manual for further details Delamination Interface Model 25 Delamination properties are assigned to interface elements to model delamination between elements The model behaves linearly until the threshold strength 1s exceeded Linear strain softening behaviour then occurs until the fr
35. giving results at each time step Both Transient Dynamic Analysis and Transient Thermal Analysis are available Q Eigenvalue Analysis is available to compute the Natural Frequencies of a structure or to carry out an Eigenvalue Buckling Analysis in order to estimate the maximum load that can be supported by a stiff structure prior to structural instability Eigenvalue Stiffness may also be performed on the stiffness matrix at a selected stage of an analysis This facility can be used in conjunction with a nonlinear analysis to predict structural instability or bifurcation points during a geometrically nonlinear analysis LI Fourier Analysis provides an extended form of axisymmetric analysis where applied loading can be considered to be non axisymmetric when applied using a Fourier distribution around the circumference LI Thermo Mechanical Coupled Analysis either performs the thermal and structural analyses simultaneously or one after the other with transfer of data between them via an additional data transfer file The following analysis types are also possible but the tabulation of the analysis control is not fully supported by LUSAS Modeller Q Harmonic Response Analysis The behaviour of a structure subjected to vibrating loads can be analysed without the need for a full dynamic step by step analysis See also Modal Response analysis Q Temperature dependent materials The definition of temperature dependent materials in a tabular form are
36. intersection is found a warning will be issued ZO A Line by intersection LI By Manifolding via projection Existing Lines may be projected or laid onto an existing Surface A Surface to be projected onto is selected followed by the Line to be projected and the Geometry gt Line gt By Manifolding menu item is used to create the new manifolded Line The new Line is created normal to the selected item and will lie on the map of the underlying Surface LI By Manifolding via Point creation Lines can also be created directly onto a Surface by creating points lying on a surface use the Geometry gt Point gt Surface menu item prior to using the Geometry gt Line gt By Manifolding menu item to create the manifolded 78 line Points created prior to choosing the command can be but do not have to be on the boundary of the Surface In this example Points 7 and 8 lie within the Surface boundary while Points 13 and 14 lie on the boundary Arc and Circle Definition Arcs and circles are defined from the Geometry gt Line gt Arc Circle menu item Chapter 4 Q From Coords Points Coordinates can be entered manually or taken from selected Points The coordinates define the arc in one of three ways Start Point Bulge Point and End Point Defines an Arc or Circle which passes through three coordinate points In this example Line 1 is defined by selecting Points 1 2 3 and specifying Point 2 as the bulge point
37. larger variations Line Mesh Spacing By default elements are evenly spaced but this can be user defined Non uniform spacing is specified by clicking on the Spacing button from the Line mesh dialog then using one of the following methods Q Uniform Spacing Q Uniform Transition Specify a ratio of the first to to o last mesh division length The spacing ratios are assigned in the direction of the line to which they are applied This example uses a ratio of 4 which is the ratio of the length of the first element to the last To reverse the mesh spacing the ratio could be specified as 0 25 or the Line could be reversed 122 Chapter 6 LI General Spacing Enter a grid of numbers which defines the individual segment length ratios explicitly They are specified in the form e Number Defines the number of elements at this ratio from the start of the line as defined by the line direction The numbers must add up to the number of divisions specified e g for the example below 2 2 4 divisions Ratio Defines the spacing ratio of the elements in the 1st column to the total number of elements This example uses general spacing 2 2 2 4 spacing ratios are applied in the direction of the Line When specifying spacing the Line direction is important as the spacing is defined from the start to the end of the line If the spacing appears to be in the incorrect direction the line may be reversed by selecting the Line and using the
38. section slice A 2D slice through a 3D model on which contours can be displayed The slice can be further interrogated using a section line to obtain a graph dataset See also section line graph dataset segment A section of a contact surface On a slideline a segment is an element edge and on a slide surface a segment is an element face In addition an individual screen of graphics information processed during a LUSAS animation is termed a segment seismic analysis An analysis of the effect of an earthquake on a structure See also spectral response semi coupled A coupled analysis in which the structural and thermal analyses are run separately and one before the other See also coupled analysis fully coupled 460 Index semi loof beam A curved line element based on the semi loof formulation See a so semi loof shell semi loof shell A 3D plane stress thin shell element based on the semi loof formulation where the element hinge or loof rotations are lumped together at the edge mid side nodes session file All commands issued during a LUSAS session will be recorded in a session file This may be replayed to recover any work lost after a system crash shear area The cross sectional area of a structure that can be said to react transverse shear loading shape functions Mathematical mapping functions used to define the variation of displacement or other variables within an element See also isoparametric mapping s
39. stl Stereolithography data files In addition to these interface files search area topology files inf can be imported into LUSAS for graphical cross checking These files which contain details of search areas used by Autoloader are converted into geometric line and surface data in LUSAS Q Search area topography inf Autoloader generated search areas 96 Chapter 3 Summary of Interface File Import Export Capability Interface file name and extension CMD cmd SOLVER Data File dat DXF dxf IGES igs LMS CADA X nf NASTRAN Bulk Data Files bdf dat ANSYS cdb ABAQUS input PATRAN def STEP step stp STL stl Notes Import file into LUSAS YES YES YES YES YES YES YES YES YES YES YES Export file from LUSAS YES NO YES YES YES NO NO NO NO YES YES e See Importing Geometry Data for details of how to import interface files e See Importing Mesh Data for details of how to import finite element data files created either by the prior running of an analysis in LUSAS or by importing interface files from other supported third party software applications e DXF IGES and STEP files often contain much more detailed information than is required to create a finite element model so a certain amount of model tidying should be expected after carrying out an import File Import Geometry data from interface files can be imported using the File gt Import menu item W
40. 0 8 0 8 0 8 0 8 0 8 0 8 Factor used for maximum combination 0 7 0 7 0 7 0 7 0 7 0 7 0 8 0 7 Factored nodal results 5 x 0 7 3 5 5 x 0 7 3 5 10 x 0 7 7 20 x 0 7 14 15 x 0 7 10 5 10x1 5 15 5 X 0 7 3 5 Smart combination Max 15 Not used Not used Not used Not used Not used Used Not used Smart combination Min will assemble results from the loadcases using just the permanent factors given for positive load effects and using permanent variable factors for negative load effects for number of negative load effects specified by the number of Variable loadcases to consider the remaining negative load effects will only use the permanent factor The number of load effects summed is restricted to the number of loadcases specified and the other loads are discarded The loadcases used are the most adverse for example the most negative for min combination and all other load effects assembled are discarded Also with the variable loadcases set to one the min combination will include only negative load effects all positive load effects are discarded 396 Appendix A Nodal Permanent Variable Factor used for maximum Factored nodal Loadcase result factor factor combination results Temperature 5 0 7 0 8 0 7 5 x 0 7 3 5 Used Wind 5 0 7 0 8 0 7 5 x 0 7 3 5 Not used Settlement 10 0 7 0 8 0 7 10 x 0 7 7 Used Live load 1 20 0 7 0 8 0 7 0 8 20
41. 2 A copy of Line 5 is defined which replaces Line 5 in the definition of Surface 2 Points are unaffected 109 Chapter 4 Modeller Reference Manual L Unmerge Line in VolumeUnmerge Line 1 in Volume 2 A copy of Line 1 is defined joining the same end Points The new Line replaces Line 1 in the definition of the affected Surfaces in Volume 2 Q Unmerge Surface in VolumeUnmerge Surface 1 in Volume 2 A copy of Surface 1 is defined which replaces Surface 1 in the definition of Volume 2 110 Chapter 4 Case Study Forcing Features to Merge Sometimes when creating the geometry duplicate features are created If these have different assignments the default merge setting will prevent coincident features from merging In this case it is useful to request the merge settings to ignore assignments LUSAS can be forced to merge duplicate features in the following way 1 Set the merge status to ignore assignments by choosing the File gt Model Properties dialog box Geometry tab and pick Ignore assignments for the Merge action 2 Select the whole model using Edit gt Select All Then merge the model features using the Merge Features button T on the Advanced Define toolbar and pick the option to merge defining geometry 3 Reset the merge status to Exact Note If some features have been previously unmerged these must first have their merge status reset to Mergable using Geometry gt Feature type gt Make Mergable Changi
42. Damping is usually specified when distributed viscous and or structural damping factors are required for modal damping control A modal damping analysis is performed as part of an eigenvalue analysis Defining Damping Structural or viscous damping is defined from the Attributes gt Damping menu item and assigned to features in the usual way Mass and stiffness Rayleigh damping parameters are linked with the corresponding reference circular frequency value at which they apply ina damping attribute If more than one set of damping values is defined linear interpolation is used to calculate damping values at intervening frequencies Birth and Death Activation Deactivation of Elements Birth and death enables the modelling of a staged construction process e g tunnelling or bridge construction whereby selected elements are activated and deactivated as the simulation process requires Birth and death attributes are defined from the Attributes menu and are assigned and manipulated in the same way as other attributes All elements to be used in the model are defined at the start of the analysis To model the absence of a part of the model it is assigned a deactivate attribute In structural analyses the underlying elements have their stiffness matrix reduced in magnitude while for field analysis the conductivity matrix or other analogous quantity is reduced This ensures the deactivated elements have a negligible effect on the behaviour of the r
43. Domain option and choose Implicit Dynamics from the combo Set the initial time step and response time as required Notes Supports should be assigned to the loadcase If the support conditions are to be modified part way through the analysis the response time in the Nonlinear and Transient control should be set to terminate at the time the supports are to be modified and a second loadcase should be created to which the modified supports are assigned A Nonlinear and Transient control should be then set on this loadcase which terminates at the end of the analysis or when a future support is to be modified 256 Chapter 6 Chapter 6 Utilities About Model Utilities Model utilities differ from model attributes in that they are not intended for assignment to the model geometry A utility however may be used in the definition of geometry or attributes or to control an analysis or to provide a particular functionality such as to define a load combination or produce a report for example Details of the features and use of many of the utilities listed below are provided in other relevant chapters of the manual Annotation utilities for example are described in the Chapter 2 Using Modeller in the Annotating the Model section The remainder are described in this chapter The complete list of LUSAS utilities accessed from the Utilities menu is shown below LI Mesh mesh node measurement the controlling of automatic remeshing and sav
44. Geometry gt Line gt Reverse menu item If desired the element spacing can also be defined using a background grid mesh The use of a background mesh is specified when the mesh attribute is assigned to the Line Line Element Axis Orientation The element x axis always runs along the Line Orientation of the local y and z axes of 3D beam elements may be defined using a beta angle or a local coordinate when the Line mesh attribute is assigned to the Line By default the element z axis coincides with the global Z axis and the element y axis forms a right hand set Elements may also be orientated using a local coordinate which is assigned to the geometry End Releases for Beam Elements Freedoms at the ends of a Line can be freed to rotate X or translate using an element with end releases See the Element Library for more information on these we element types When defining a Line mesh attribute with a valid element selected click on the End Release button Releasing beam element end freedoms can be used as an alternative to using a joint element for example when defining a pin between two beams 123 Modeller Reference Manual Meshing Surfaces Regular Surface Meshing Regular meshing is used to generate a set pattern of elements on Surfaces and Volumes Only surfaces which are regular defined by 3 or 4 lines can be meshed using a regular mesh pattern LI In order to generate a regular grid mesh pattern the number of
45. Next Line 2 is defined by selecting P4 and P5 then entering the coordinates to define a bulge Point P6 which is not actually created Start Point Directional Point End Point and Radius Defines an Arc or Circle between two coordinate points to a specified radius A third coordinate point is required to indicate the direction in which the arc or circle bulges In this example arcs are created from Point 1 to Point 2 with a radius of R using Direction Point 3 Choosing Minor Arc creates Line 1 while choosing Major Arc creates Line 2 A Major Arc subtends an angle greater than 180 degrees at the arc centre while a Minor Arc P3 L1 D2 L2 ps PA P0 xX yY PI 19 Modeller Reference Manual subtends an angle less than 180 degrees e Start Point Centre Point and End Point Defines an Arc or Circle between two coordinates with a third coordinate defining the centre of the arc or circle The centre must be equidistant from the start and end points In this example arcs are created by selecting Points 2 3 4 with Major centre Point 3 as the arc centre Choosing Minor Arc defines N 7 re PA Line 1 Choosing Major Arc PON a defines Line 2 dotted line for rn clarity LI Tangent to Lines Inserts an Arc or Circle with a specified radius tangent to two selected Lines The selected lines must be straight Lines or Arcs In this example Line 3 is created by selecting Lines 1 and 2 then sp
46. Once created the geometry features are then assigned attributes materials properties and thicknesses loading supports and mesh element type etc to fully describe the model prior to an analysis taking place One of the many benefits obtained from using this feature based modelling method is that built in associativity ensures that if the model geometry is amended all assigned loadings supports geometric attributes and particularly any mesh assignments and arrangements are automatically updated to suit When a feature based geometry model is being edited all user interface menu items appropriate to the application software in use are available Mesh only models Mesh only models are comprised of nodes and elements and do not contain any geometric feature types or indeed any geometric data at all They are created by importing finite element data files created either by the prior running of an analysis in LUSAS or by importing data files from other supported software applications The File gt Import Mesh menu item is used to do this During the mesh import process LUSAS Modeller creates separate Groups for each element type encountered and for models created from LUSAS data file these will be familiar LUSAS element names For models created from other third party software they will be the names used within that system whatever they may be An option to create additional groups during the import process based upon the element material type is
47. Patch loads and Internal Beam Point and Internal Beam Distributed loads which incorporate variable loading implicitly in their definition Values of loads which are applied to elements will be evaluated at the element centroid LI Geometric attributes containing a variation are tabulated as multiple geometric properties An additional parameter is added to the assignment to relate to the original defining attribute number for use in post processing LI To vary geometric properties along bar or beam elements use the geometric beam tapering facility LJ Variations in materials are limited to elastic material values and certain joint properties Attributes containing a variation are tabulated as multiple material properties containing the material value calculated at the element centroid An additional parameter is tabulated to the assignment data chapter in the data file to relate to the original defining attribute number for use in post processing LI When defining supports the spring stiffness values can be varied but the spring stiffness values are not scaled when drawn in post processing LI Checking of the assigned variations can be carried out by contouring the assigned data using an unsmoothed contour display Q Variations of the Rayleigh parameters cannot be contoured as they are calculated at element centroid positions Field Variations Field variations allow a variation according to a mathematical expression in terms of coordinate va
48. Q is va 21 o A 2nf 296 Chapter 7 An eigenvalue analysis of the stiffness matrix has no physical meaning except that a zero magnitude implies a critical point of some description An eigenvalue analysis in LUSAS will include the gyroscopic effects in the stiffness matrix for certain elements see Element Reference Manual if you use a CBF load to simulate the angular velocities of the shafts note that this requires a nonlinear analysis Such a natural frequency analysis would give the frequencies of the lateral modes of vibration The physical effect modelled by the centripetal stiffening facility for eigenvalue analyses is the stiffening that a rotating be as a result of radial expansion and the corresponding increase in hoop stresses These stresses effectively stiffen the structure and can significantly increase the eigenvalues See the Theory Manual for further information Ensure that mass normalisation is chosen for the eigenvalue analysis if it is to be followed by a spectral or harmonic analysis It is possible to use constraint equations in both an eigenvalue and a harmonic response analysis in LUSAS However the Sturm sequence check may prove unreliable unless the fast Lanczos solver is used Non zero rigid body eigenvalues may be experienced when using QSI4 elements This is due to the method used to obtain the lumped mass matrix for this element a consistent mass matrix not being available QSL8 and QTS4 e
49. Supported elements are shown in the table below Q Kigenvectors and Frequencies Node displacements for all nodes specified in the model description are output to the neutral file in the global co ordinate system When mode shapes are read by LMS the mode shape numbers will not necessarily be the same unless all eigenvectors are exported Modeller mode shape numbers are preserved during an export but are not preserved when read into the LMS software Q Element Matrices The element matrices stiffness and mass are output in element type order There are three sections required to define a matrix These are MATSHP MATVAL and MATDEF By definition elements of the same type have the same matrix shape therefore for each element type there is only one MATSHP keyword However each element matrix contains different values and hence gives rise to one MATVAL and MATDEF statement per element matrix To reduce the amount of matrix data output to the neutral file and to keep its size to a minimum only the non zero active columns of the element matrices are processed 65 Modeller Reference Manual Supported Elements The following elements are supported by LMS Bars Beams Plates Shells Membranes Solids Joints Triangular Quadrilateral Tetra Penta Hexa BAR2 BEAM TPM3 QPM4 TH4 PN6 HX8 JF3 BAR3 BMS3 TPM6 QPM4M TH4E PN6E HX8M JPHS BRS2 BRP2 TPM3E QPM4E TH15 PN15 HX20 JRP3 BRS3 GRIL QM8 JNT3 TF3 QF4 JNT4 TTF6 QSC4 TRP3 QTF8 RPI4 TS3 QSI4 TT
50. Surface 89 Modeller Reference Manual Q At a Point Splits a selected Surface at a single Point defined on the surface inside the boundary Four new Surfaces are created by manifolding straight Lines or arcs onto the existing Surface using the relative position of the splitting Point In this example the original Surface is split at Point 5 The resulting Surfaces 2 5 use parametric space to calculate boundary Point positions LI In Equal Divisions Splits a selected Surface into separate Surfaces at a specified number of equal divisions The direction of the split is expressed using local Surface axes In the example shown here the original Surface is split in its local x direction into equal divisions forming 3 new Surfaces Q At Parametric Distances Splits a selected Surface into separate Surfaces at specified parametric divisions For example specifying the parametric distances as 0 25 and 0 75 will split a Surface at the 1 4 and 3 4 position in parametric space in the specified local direction In this example the original Surface is split in its local y direction at parametric divisions 0 25 0 75 90 Chapter 4 Joining LI By Joining Defines a number of Surfaces by joining two sets of selected Points or Lines The first set of Lines should be added to selection memory the second set should be selected The Lines should pair up equally Surfaces are joined according to Select the order in
51. Surface in the definition is the selected Surface The local x and y axes may then be changed using the Cycle surface command LI Cycle Surfaces or surface solid elements in a mesh only model may have their definition order cycled and Volumes may have the definition of the first Surface in the Volume definition cycled and for mesh only models Elements may have the definition of the first Face in the Element definition cycled In this example the original Surface defined by Lines 1 2 3 and 4 is shown in grey Cycling by changes Surface definition to Lines 2 3 4 1 Cycling again defines the Surface as Lines 3 4 1 2 Surface normal directions remain consistent throughout Cycle 1 Cycle 2 Cycle 3 Wis ags LI Cycle Relative Cycles the definition order relative to the first feature of the same type in the current selection Surfaces and Volumes or surface solid elements in a mesh only model may be reoriented in this way In this example Surfaces 2 3 and 4 are cycled using Surface 1 shown greyed as the reference orientation LI Cycle to Neighbours Mesh only models Cycles the element axes of all 112 Chapter 4 neighbouring and selected elements relative to the first element in the current selection Whilst similar in effect to the Cycle Relative option for the example shown above which would obtain the same result for that particular example it caters for the case where for certain orientations of elements the cycle r
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53. The most accurate results available from the analysis Q Element Nodal Unaveraged nodal results for visible elements Nodal results are extrapolated from the Gauss point values within each element Q Coordinates When the optional Coordinates checkbox is enabled the global X Y and Z positions of the nodes or gauss points as appropriate are included as separate columns in the printed output If a column heading is double clicked the results will be sorted in ascending or descending order based upon coordinates This enables sorting of nodal and gauss results data by coordinate Extent The printed results for selected loadcases are governed by the following extent options 372 Chapter 8 Q Elements showing results default option which prints results only for those elements that are displaying them in the Modeller view window Q Visible model prints results all elements that are visible in the Modeller view window Q Full model prints results for all elements of the model regardless of whether the elements are visible or displaying results in the Modeller view window Q Specified group prints results for a specified named group Only active if group names have been defined Printed results for automatically created slices When section slices have been defined on a 3D model with corresponding groups being automatically created in the Groups treeview the results for just the automatically defined groups slices can be pr
54. The undeformed plot is drawn using a lighter pen colour to further clarify the display 345 Modeller Reference Manual Notes e Other results visualisations may be displayed on the undeformed or deformed shape as required e When carrying out contact analysis a unit deformation factor should be used to avoid misleading results e When an analysis involves the activation and deactivation of elements inactive elements may be hidden using the show activated only option on the visualise page of the mesh properties dialog Contours Contours display the results of the active loadcase on the model as colour fringes or lines of equal results value Contour Display Features LI Contours may be plotted using colour fill and or contour lines Fill and line contours displayed together are useful for emphasising the contour levels Contour labels are available if required LJ Contours may be plotted on the deformed loaded shape or the undeformed shape LI Contours may be plotted using averaged nodal results to give a smoothed plot or unaveraged nodal results to contour the results on an element by element basis revealing any inter element discontinuities This is useful for checking mesh discretisation error and for displaying results across geometry or material discontinuities L Contours can be plotted on shells solids bar and beam elements on fleshed members and on layers of composite elements Q The maximum and or minimum res
55. Thermal Analysis Where time effects are significant in a field problem a transient field analysis should be performed In a similar manner to structural dynamics transient field analysis involves the evolution of a new field variable distribution from a set of initial conditions via a set of transition states evolving through time Transient field analyses are controlled using the nonlinear and transient control The initial conditions of the body must firstly be prescribed This may be done by performing the appropriate linear or nonlinear steady state analysis Linear transient analysis Integration Scheme beta Crank Nicholson 1 2 Euler 0 Galerkin 2 3 default Backward difference 1 The transient problem is integrated through time using a 2 point integration scheme The type of integration scheme maybe changed on Advanced Time step parameters dialog accessed from the nonlinear and transient control dialog by specifying the parameter beta Some of the more common 2 point integration schemes and their associated beta values are shown in the table above Notes e Inthe limit the final solution should be the same as the steady state analysis subject to the new loading and boundary conditions the transient analysis merely models the thermal inertia in moving from the initial to the final conditions The body property which is used to describe this inertia is the effective heat capacity e When choosing an increment of time the stabil
56. This option may be invoked from the Edit gt Associate Operations Downwards menu item Associate operations downwards is set on by default Selection Memory Some operations require features to be stored in selection memory The selection memory commands are available from the Edit gt Selection Memory menu item or from the context menu enabled by right clicking in the graphics area The selection memory commands are 32 Groups Chapter 2 LI Set clears the selection memory and set the contents to the items in the selection Q Add adds the selected items into selection memory L Remove removes the selected item from selection memory Only available if the selected item is already in selection memory Q Recall places all objects in selection memory into the main selection Objects are not removed from selection memory LI Clear clears the selection memory Q Browse displays the Selection Memory browse window Selection Colour The Pen used to draw items in the selection or the selection memory may be changed from the Window properties To display the Window properties choose properties from the window context menu enabled by right clicking in the graphics area User defined groups are used to conveniently store selected collections of objects geometry nodes or elements under a collective name For example a certain set of geometry might be grouped together with the name Nut whilst another set might be grouped and n
57. Treeview shows the display status of each layer m A coloured layer symbol indicates that the display of a layer has been turned on m A greyed out layer symbol indicates that the layer has been turned off A red circle witha line through it indicates that no results are loaded or currently available for this layer or inappropriate settings are currently set Note Double clicking on a layer name whether or not is it On or Off will display a Properties dialog where the style of the viewed layer can be changed Clicking OK will turn On a previously turned Off layer Layers available The following layers can be added removed have their display turned on off and be generally manipulated from a view window L Geometry L Mesh LJ Attributes 2 Modeller Reference Manual Q Labels LJ Annotation Q Utilities LI Contours LI Vectors LJ Deformed mesh LI Diagrams LI Values Note The order in which the layers are drawn is defined by the order or the layers in the Treeview The top layer in the Treeview is drawn first to the screen If the display of one layer is eclipsed by another layer i e the mesh is eclipsed by the contours or the annotation is eclipsed by the deformed mesh the eclipsed layer can be moved down in the Er Treeview by selecting it then dragging and dropping it to a new position to cause it to be drawn following a particular layer Selecting Model Features Items displayed in the graphics w
58. Treeviews can be moved to different tree frames by drag and drop This is useful if you prefer to see more than one treeview at the same time Attributes can be assigned to the contents of groups by copying the attribute and pasting it onto a group in the treeview By saving a view using the Window menu and naming it default every new window will use the saved view Pressing the Ctrl and Break keys together will interrupt the current process For larger models save time by setting the manual redraw option Window menu and manually redraw F5 key at any time For larger models save time by setting the manual resize option Window menu and manually resize at any time For larger models save time by locking the mesh whilst making several geometry or mesh changes Either manually remesh or unlock once finished to reinstate automatic meshing It is usually much quicker to undo several events all at once than to undo them individually Many additional toolbar buttons are available via the View gt Toolbars gt Customise menu item Selection is possible using several different criteria e g connectivity element type see the Advanced Selection dialog To retain a record of the commands used in a session use the File gt Script gt Start Recording menu item You may use the Esc key to close any dialog Holding down the Shift and Control keys while selecting will remove from the current selection For example the current selection c
59. Volume feature mesh records LUSAS feature types supported by the DXF export facility are listed in the table below 61 Modeller Reference Manual LUSAS Feature Mesh Exported as DXF Entity Feature LINE straight 3DLINE Feature LINE arc ARC Feature LINE spline POLYLINE Feature SURFACE straight edged 3DFACE Feature SURFACE general curved 3DLINE ARC POLYLINE Mesh LINE linear or quadratic edge 3DLINE Mesh SURFACE linear or quadratic face POLYFACE MESH Mesh VOLUME linear or quadratic face PLOYFACE MESH Notes The exporting of models generates DXF files containing structural information only This facility is not intended for exchanging graphical information for this purpose picture files should be used Only the element faces are exported when exporting volume feature mesh records For further information on the DXF file format users are referred to the AutoCAD Reference Manual IGES Import Export IGES files are imported from the File gt Import menu item When a file is selected the import process may be controlled from the Advanced button by specifying import parameters LUSAS Model geometry may be exported to IGES using the File gt Export menu item Notes IGES data is made up of a number of discrete surfaces These need to be merged together to create volumes which can then be meshed When IGES import is used the option to crate hollow volumes is automatically invoked Any active loc
60. Y Translation L1 L1 88 Chapter 4 Offsetting LI By Offsetting Defines a Surface at a specified distance normal to a selected Surface The positive offset direction is defined by the Surface normal unless an additional Point is selected Splitting Surfaces Surfaces may be defined by splitting an existing surface in a number of ways using the menu items under Geometry gt Surface gt Splitting Surface splitting commands contain an option to automatically delete the old Surfaces and Lines which have been split Attributes assigned to the split feature will automatically be assigned to features of the same type created during the split process The following splitting methods are supported LI By Line Splits a selected Surface at an existing Line The end Points of the Line must lie on different boundary Lines of the Surface It is advisable to split curved Surfaces using Lines that are manifolded over the Surface In the example shown here the original Surface is split at Line 5 Points 5 and 6 defining Line 5 must lie on the original Surface boundary Lines LI By Points Splits a selected Surface at two boundary positions indicated by Points A new Line will be manifolded onto the existing Surface and the Surface will be split at this Line In the example shown Surfaces 2 and 3 are created in the parametric space of the original Surface using the Points on the boundary The new Line is manifolded onto the original
61. a deactivated element may be redistributed in the system this has the same effect as re assigning very weak material properties to the element Q Fractional Redistribution A percentage of the internal force to be redistributed is specified Provides a solution which is part way between the two extremes Any remaining internal equilibrating force associated with a deactivated element is maintained in the system until the element is subsequently activated When an element is activated it is assumed that the element has just been introduced to the model although all elements must be defined at the outset The current deformed geometry for that element is taken as the initial geometry and the element is assumed to be in a stress strain free state unless initial stresses or strains are defined All internal forces that exist in the element are redistributed and the computed strains are incremented from the time at which the element becomes active Excavation Stage 1 Top layer of soil deactivated and lining activated Lining and soil elements duplicated in the model PAES in dra s aaan Li n j ng FAW SSE CAIN SSS nstructed Soil i ES N excavated ett san CA a Ne N Tunnel Excavation Stage 2 Second layer deactivated as soil excavated Surrounding lining elements activated LAINS IWS SS TITAS SSS FHSS T AU ae os Ne constructe INK Soil excavated 224 Tunnel Excavation Stage 3 Remaining seco
62. a window you have the choice of what to reload e g colours layers etc View Axes LI Visualise coordinate system Visualises the active coordinate system in the graphics area using the position and style specified The active coordinate system may be set from the Geometry tab of the model properties dialog Q Anchor point Anchors the coordinate axes to either a model coordinate or a frame window coordinate LI Styles Defines the style used to draw the coordinate axes and optionally sets the font used for axes labelling Customise Startup Templates Startup templates can be used to pre load the Attributes Treeview with selected attributes for a particular analysis set default mesh or material types or define preferred colour schemes to name just a few uses User defined startup templates are created by recording the setting of a variety of selections and then associating the recording with a template name Case Study Creating a Startup Template In this example a startup template will be created to define a material type set it as the default and also set user defined display colours for the Modeller graphics window 1 Run LUSAS and create a new blank model of any filename 2 Select File gt Script gt Start Recording and enter my_defaults as the filename 3 Select Attributes gt Material gt Material Library choose Mild Steel and click OK 4 Inthe Attributes Treeview right click on Mild Steel Ungraded and select S
63. activation volume LI Mass density Q Linear Spring stiffness LI Bulk Modulus Q Maxwell element spring constant Q Maxwell element Newtonian dashpot viscous parameter Q Damage properties See the Theory Manual for further details Concrete Creep and Shrinkage CEB FIP Model 86 Concrete material properties to CEB FIP Model Code 90 are defined from the Attributes gt Material gt Specialised menu item This model uses a simplified linear approach to represent creep This assumption assumes that the service stresses in the concrete will not be exceeded and hence may not predict the effects of unloading or load cycling accurately Material Properties The following material parameters are required LW Young s Modulus at 28 days LI Poisson s Ratio Q Mass density 0 Coefficient of thermal expansion Q Mean compressive strength at 28 days Q Cement type LI Relative humidity LI Nominal size 184 Chapter 6 Notes e The CEB FIP Code states that the modulus of elasticity at 28 days may be estimated from Eo 2 15x 10 x fom 10 7 e The cement type can be Slow Hardening Normal or Rapid Hardening or Rapid Hardening High Strength Normal or Rapid Hardening is the default option e The Nominal Size is computed as 2A u where A is the area of the cross section and u is the length of the perimeter of the cross section that is in contact with the atmosphere Nominal Size should be compatible with the units chosen for the model
64. analysis the deformed shape for each influence point may be viewed checked by adding a deformed mesh layer to the Layers l amp Treeview and then in the Loadcase cH Treeview setting each loadcase active in turn See Vehicle Load Optimisation for details of how to generate the most adverse loading for defined influence surfaces for bridge loading Vertical axis The vertical axis dialog is accessed from the Utilities gt Vertical Axis menu item The vertical axis setting specifies whether the model X Y or Z direction is to be used as the vertical axis It has the following uses Q Itis used to determine the direction that gravity loading will be applied if added using the Bridge gt or Civil gt Gravity menu item Q Itis also used to determine the direction that gravity loading will be applied if it has been specified as a property of a loadcase Q Itis also used to define the initial vertical axis and orientation of element types and library items as displayed on the Geometric Line dialog prior to them being added to a model Q It also defines the model orientation that is viewed when using the isometric dimetric and trimetric views Note that setting the vertical axis on the Vertical axis dialog will supercede any vertical axis setting defined on the Direction definition dialog Direction Definition Specifying a direction definition sets the vertical longitudinal and transverse axes for a model to assist with model orientati
65. and crush pattern 352 Chapter 8 Results On Sections Slices Through A Model Results can be plotted on sections or slices through a model by choosing the following menu commands available from the Utilities menu LI Section through 3D Cross sections may be taken through a three dimensional solid model to display results on a slice Results are calculated at pseudo nodes formed at the intersections of the slice with the element edges by linear interpolation of the nodal results LI Graph through 2D Graphs of results may be created along a line through a 2D continuum model or on a line through a section from a 3D model Results are calculated at the intersections of the line section and the element edges hence a finer mesh will produce more sampling points Force and moment values along the slice may also be computed Section Through a 3D Model Slice sections may be cut at arbitrary positions through the model using the cursor to define either a horizontal or vertical slice in the View window Slices may be generated in any plane by rotating the model to the desired orientation before a section is cut By default the location of an arbitrary slice section through a model is not saved with the model However when cutting a slice section through the model an option to create an annotation polygon is provided This annotation polygon effectively defines the location and orientation of the cutting plane and does get saved with the
66. are not imported into newly created mesh only models so these need to be defined as necessary to obtain specific types of results as for example to get moments around a cylindrical axis Restricted unsupported functionality for mesh only models With reference to the user interface menus for feature based geometry models 17 Modeller Reference Manual The Utilities gt Slice resultants beams and shells menu item is not currently supported The Utlities gt IMDPlus gt Moving load wizard functionality is not currently supported The Bridge gt Moving load menu item is not currently supported The Bridge gt Prestress Wizard gt Tendon profile and Multiple tendon prestress menu items are not currently supported The Bridge gt Prestress Wizard gt Single Tendon design code options are not currently supported Single tendon definition is only permissible by importing data from a spreadsheet Reference paths can only be created currently by typing in the coordinates defining the path Model Properties The Model Properties dialog allows many settings relating to the current model to be defined Model properties may be accessed from the File gt Model Properties menu item or by right clicking the model name top level in the Er Treeview and selecting Properties from the context menu The model properties are defined on the following tabs Q General LI Notes LI Geometry Q Meshing UL Attributes Q Solution UL Defau
67. as body force loading consistent mass Distributed between the degrees of freedom The mass matrix is not diagonal See also lumped mass constant load level When the load is applied in fixed increments and the chosen iterative algorithm is utilised to obtain convergence at each load level See also line search arc length method constitutive relationship The empirical relationship between stress and strain May include thermal effects and be nonlinear with irreversible plastic deformation constraint equation An additional relationship between different freedoms of a structure Also known as multi point constraints contact The action of bringing one portion of a finite element mesh into a position where it impacts on another part of the mesh See a so impact contact node Any node assigned for use on a slideline surface Also known as a slideline node contact zone The area of a model that is considered to be touching another part See also zonal detection contacted node A slideline node currently considered to be in contact with the opposing slideline surface context sensitive help Available by clicking on the Help button on the main toolbar or by pressing Shift F1 on the keyboard This puts the cursor into help mode next click on any toolbar button menu entry or other part of the LUSAS interface for context sensitive help Also know as pop up help See also help continuum element Finite element formulation base
68. aspect ratio is high an extra preconditioning option exists which will often yield a solution faster than using a direct solver Care should be taken when solving problems with high aspect ratios thin or elongated or excessively curved or distorted elements or extreme or widely disparate material properties since all of these can lead to ill conditioning Also the convergence of the iterative solver is 310 Chapter 7 related to the condition number of the stiffness matrix which becomes worse for ill conditioned problems The conjugate gradient iterative solver can be configured using the following parameters Drop tolerance a value between 0 0 and 1 0 which measures the amount of new non zero entries known as fill in allowed to remain in the preconditioning matrix during the incomplete Cholesky factorisation of the stiffness matrix The default value is 1 0 leading to a very sparse preconditioning matrix suitable for well conditioned problems For more ill conditioned problems however this value should be decreased exponentially and values in the range 1 0e 3 1 0e 6 are recommended The lower this parameter becomes the larger the preconditioning matrix will be giving rise to fewer iterations during the conjugate gradient solution although each iteration will take longer to process This parameter affects all preconditioning techniques although the effect is less pronounced for the decoupled techniques Maximum number
69. at each division In the example shown ti Line 1 is split into 4 new Lines of C equal length and the original Line is deleted P1 Q At Parametric Distances Splits an D gt existing Line into a number of divisions based on specification of parametric distance values along the Line The direction of the existing L1 C line is used to calculate the splitting positions A new line is created at each division In this example Line 1 is split at a parametric distance of 0 75 Line 2 is created at 3 4 of the ie original length and Line 3 at 1 4 Specification of a parametric divisions list as 0 1 0 5 0 75 will split a line at 1 10 1 2 and 3 4 distance into 4 new lines PZ Combined Lines A Combined Line is a Line which is composed of several continuous individual Lines Combined Lines may be used in exactly the same was as other Lines to allow Surfaces to be 82 Chapter 4 meshed using regular mesh patterns This is especially useful for meshing surfaces defined by more than four Lines Combined Lines are defined from the Geometry gt Line gt Combined Line menu item _ Lines Defines a Combined Line from two or more selected Lines that are continuous but do not form a closed loop Any number and type of existing Lines can be used to define a Combined Line In the example here Lines 3 and 4 are used to define Combined Line 6 Lines 3 and 4 are replaced in the definition of Surface 1 Notes e Automatic nu
70. at the last mouse click e Right clicking in the Selected box in the status bar allows access to a menu of selected objects Choose Previous when you have cycled the selection once too many e The browse selection window gives useful feedback on which items are currently selected e The browse cyclable items window shows all items which could possibly be selected at the chosen position e To select an item with a known name use the Advanced Selection dialog e To show the location of a named item select it using Advanced Selection right click on it in the Browse Selection window and chose find from the menu e Ifa message in the text output window refers to a particular object by name double click on the message for help finding that object 416 Appendix D Clicking in the Z box in the status bar views the model from the positive end of the Z axis and similarly with X and Y Hold down Ctrl while clicking to view from the reverse side Clicking the advanced button on the LPI command bar lets you define macros for frequently used commands The members of a group can be examined from the group s property page The jump to button on the hierarchy tab of an object s property page can be used to select and show the properties of connected objects The assigned in active loadcase option on an object s property page allows you to view either assignments in the active loadcase or in any loadcase
71. automatically generate the lower order features from which to define them Furthermore due to feature associativity when a lower order feature for example a point is moved the higher order features defined by it for example a line is also moved Features may be deleted from the model provided they are not referenced by a higher order feature For example a Line may not be deleted if it is used in a Surface definition Notes e Attributes are assigned on a feature basis therefore the positions of geometric and material discontinuities supports and loads must be carefully considered when defining the features e By default coordinates are expressed in terms of a global Cartesian axis system Local coordinates may be used by setting a pre defined local coordinate active This is achieved by defining a local coordinate and choosing the Set Active command on the context menu See Local Coordinate Systems e Geometry can be imported from other systems See File Import 69 Modeller Reference Manual Visualising Geometry There are a number of ways to visualise geometry all of which are controlled from the Geometry layer properties activated from the Geometry layer context menu The Geometry layer controls the display of all geometry If the Geometry layer does not exist or is hidden by another layer the geometry will not be drawn Show Geometry The Geometry layer properties may be set to not show certain geometry types To aid
72. averaged nodal results Most results are calculated at the Gauss points of an element and then extrapolated to the nodes using the element shape functions When the results from all elements joined at a node are added together and divided by the number of contributing elements these are known as averaged nodal results See also unaveraged nodal results Gauss point results shape functions axial force The longitudinal force along the axis of a beam See a so force diagram axisymmetry A structure that has circular symmetry of geometry material supports and loading such that a radian slice can be analysed 423 Modeller Reference Manual b matrix Matrix of element shape function derivative terms describing the relationship between strain and displacement It is used in the formation of the element stiffness matrix See also stiffness matrix d matrix background grid A collection of triangular or tetrahedral shapes which are used to specify the element edge length when meshing surfaces automatically backward Euler An implicit plasticity formulation in which the plastic strain normality condition is formulated at the trial stress position See also forward Euler bandwidth See frontwidth bar element A straight or curved isoparametric line element without any rotational degrees of freedom used to model strut or truss structures batch file A text file that contains MS DOS commands When you run the batch program
73. axes may be placed at the top bottom or middle of the chosen layer for shells the axes are placed 246 Chapter 6 on the mid surface of the shell element For details of how to choose a composite layer see Setting The Active Composite Layer Visualisation of Draping Grid The draping grid for individual lamina can be examined graphically as follows 1 Right click on the Attributes entry in the LE Treeview and select Properties 2 On the Composite tab click on Settings and select Visualise ply directions Then select Draping grid If no mesh has been assigned to a model prior to selecting this option only the draping grid and not the ply directions will be visualised For details of how to choose a composite layer see Setting The Active Composite Layer Extending the draping grid LUSAS Draped Solids and Shells grids are automatically trimmed at Surface boundaries FiberSIM and Simulayt generated grids are not If required the draping grid can be extended by one grid row to ensure the edges of the component are fully enclosed by the draping grid For FiberSIM and Simulayt grids this is specified at the file import stage accessed via the Attributes gt Composite menu item For LUSAS Draped Solids and Shells grids this is done via the Draping options on the Model Properties dialog E j pa BE T B T ti ae a T E T PO Ae T po E HE Example of draping grid being Example of draping grid being extended by one r
74. axisymmetric but the fan blades are not The use of the standard Fourier material properties is inappropriate for the fan blades since the hoop stresses introduced by the element material model provide significant artificial stiffening To alleviate this problem the use of the plane stress material model input using the orthotropic materials properties is permissible provided that the element is given adequate torsional restraint The use of this material model can be thought of as smearing the individual stiffness of the fan blades into an equivalent axisymmetric structure For Fourier elements using orthotropic properties body forces are applied using the associated load curve If the load curve is input as a series of Is and Os this is equivalent to selectively equivalent integrating the internal forces for each fan SS blade The scheme is illustrated in the diagram 0 9 Load curve definition sid Turbine 308 Chapter 7 Thermal Problems If temperature dependent material properties are used the temperature field must be axisymmetric For non temperature dependent materials a general temperature field can be input in the same manner as the other element loads Temperature loads cannot be used in dynamic or harmonic response analyses Post Processing Fourier results may be expanded using the Graph Wizard Frontal Optimisation and LUSAS Solvers The frontal optimiser is set from the Model Properties gt Solution Opti
75. based on the formula chosen when defining the spectral combination Damping may also be described in terms of the Rayleigh damping parameters and transferred from LUSAS Solver Normally the number of modes included should ensure the sum of the mass participation is not less than 90 in all significant excitation directions To obtain the design values some form of combination may be used Within LUSAS the following methods of combination are available LI Square root of the sum of the squares SRSS LJ Complete quadratic combination CQC L Absolute Sum Note When zero damping is specified the CQC gives exactly the same results as the SRSS technique Transient Dynamic Analysis Where loading may not reasonably be considered to be instantaneous or where inertia or damping forces are to be considered a transient dynamic analysis sometimes referred to as step by step may be carried out A dynamic analysis is controlled using the nonlinear and transient loadcase control properties Dynamic solution methods generally numerically integrate in the time domain The solution is progressed through time in a step by step manner by assuming some variation of the displacements and velocities over small intervals of time Within each time step the solution yields the displacements at the discrete time points representing the end of the current time step For known initial conditions successive application of this procedure furnishes the dynamic resp
76. been defined for the master section Subsequent updating of an offset value for a master section by clicking the launch dialog button Hin the Section cell of the table and entering an offset value on the Enter section dialog when Top to top Centre to centre or Side to side alignment options are selected will automatically update the offset values for all of the follower sections by an equivalent amount to ensure the sections are moved equally to re align with the master section Note that for thick beam elements the offsets are measured from the bending plane of the section to the nodal line in the local element direction This can result in both positive and negative offset values depending upon the size of the master and follower sections To move a multiple varying section beam up or down from its nodal line position only the offset for the master section need be modified because all other sections will have their offset values updated automatically to be moved by the same amount Align all sections Distance 3 aaa eee to section 1 Distance 2 Alignment Section 1 I Section 2 z Section 3 Z Bendin im o i Offset ae TY Offset i Follower section Bending Bending plane lana Sl ete oes see Follower section Wlaster section b Nodal line 155 Modeller Reference Manual Whilst not commonly used user defined individual offsets can be entered for selected sections by sele
77. body when only environmental thermal properties are required For analyses where discrete multiple bodies are considered factors such as body proximity and whether the bodies are touching or are likely to touch during the analysis become important and the choice of thermal properties changes Follow a route through the flowchart below and define your thermal surfaces using the properties given in the shaded box 228 Chapter 6 Thermal Surface Is the structure made up of discrete bodies Environment Properties or Environmental Loading OO Thermal Surface together conduction and convection effects dominant Radiation Properties Radiation Surfaces Are the bodies close E om Y Are the bodies touching include pressure effects Thermal Surface Gap Properties Thermal Gap Yes y Thermal Surface Gap Contact Properties Thermal Gap Coupled Analysis Environmental Nodes LUSAS analysis data file Environmental nodes may be used to represent the medium which separates the thermal surfaces between which heat is flowing As the length of a link directly connecting two surfaces increases the validity of the assumed flow becomes more tenuous Alternatively instead of forming a link heat could flow directly to the surroundings but in this case the heat is lost from the solution This in some cases is a poor approximation to reality
78. can be used between different kinds of computers compiler A computer program that translates a program written in a programming language into a set of instructions in the language of the computer component See group compound load a collection or set of defined discrete loads that are assigned to a model as a single loading attribute composite properties Define how individual materials are layered in a composite material concatenation Joining two or more strings together to form a single string conduction The process of energy exchange by kinetic motion or direct impact of molecules fluids or the drift of electrons metals See also convection radiation concrete model A plane stress material model that mimics the nonlinear cracking of concrete See also orthogonal cracking non orthogonal cracking cracking conjugate gradient solver A solver that iterates towards a solution judging convergence by a user defined tolerance This is in contrast to a direct solver such as the frontal solver Because the solution is inexact very sensitive to the matrix conditioning and repeated for every load case it is best suited to large solid well conditioned single load case analyses See also pre conditioned conjugate gradient solver 427 Modeller Reference Manual constant body force A load type that applies a force loading per unit volume This load type can also be used to apply acceleration loading Also known
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80. details Creep is the inelastic behaviour that occurs when the relationship between stress and strain is time dependent The creep response is usually a function of the stress strain time and temperature history Unlike time independent plasticity where a limited set of yield criteria may be applied to many materials the creep response differs greatly for different materials Creep Properties Power exponential and eight parameter uniaxial creep laws are available and a time hardening form is available for each The power creep law is also available in a strain hardening form Fully 3D creep strains are computed using the differential of the von Mises or Hill stress potential A user definable creep interface is also available which allows a programmable uniaxial creep law Stress Potential The definition of creep properties requires that the shape of the yield surface is defined The stresses defining the yield surface are specified using the Stress Potential material model If a Stress Potential model is used in the Plastic definition then this will override the Creep stress potential and will apply to both the plastic properties and the creep properties The Creep stress potential is only required when defining linear materials If a stress potential type is not specified then von Mises is set as default None of the stresses defining the stress potential may be set to zero For example in a plane stress analysis the out of plane dire
81. direction will be calculated proportionally to the patch shape Equivalent weighting values are used to calculate the portion of each discrete load that is applied to each corner of the element that it lies within The load is then applied as Concentrated Loads These weighting values are based on element shape functions and may vary with element type 205 Modeller Reference Manual Assigning Discrete Loads Discrete loads are independent of features therefore their application can be more flexible The load assignment parameters are explained below LJ Patch Transformation Changes the patch orientation For example a patch load may be skewed by applying a rotation transformation when assigning the load In the example shown right the Point load defined about local xy axes is assigned to Point 1 subject to a patch direction transformation using cb a 30 degree xy rotation about the global origin 7 Note that the local origin of the patch load is N rotated and repositioned as well as the patch itself To rotate a patch about its centre define the patch with its local origin at its centre Q Load transformation Changes the load orientation from the untransformed direction given in the load definition The transformation applies to the direction of the individual load components rather that to the patch as a whole For example it can be used to model braking loads on a 3D model that have horizontal and vertical components by sp
82. displayed on the nodes of the assigned feature and at the mid side nodes of the adjacent elements that have been moved towards the assigned feature Crack tip attribute assigned to a point in a 2D model Crack tip attribute assigned to a line in a 3D model Slidelines Slidelines are attributes which can be used to model contact and impact problems or to tie dissimilar meshes together They can be used as an alternative to joint elements or constraint equations and have advantages when there is no prior knowledge of the contact point Slideline applications range from projectile impact vehicle crash worthiness the containment of failed components such as turbine blades to interference fits rock joints and bolt plate connections Slideline properties are defined from the Attributes gt Slideline menu item The properties of a slideline are used to model the contact interaction between master and slave features such as the contact stiffness friction coefficient temperature dependency etc The figure below shows a contact application in which a frictional slideline is defined between two bodies and where tied slidelines are used to join dissimilar meshes The latter avoids the need for stepped mesh refinements between different mesh densities 234 Chapter 6 Tied slideline E D T ral T T J F E ak ee Oe r s A a ss a ay A EN AI ee ES e p T A kie EE RT X T Si oe a fo EY x 1 T F ek fN i
83. distances along a line for example entering 0 10 and 20 would specify a section at either end and at a mid point of any line that was selected and assigned this geometric line attribute Distances are mapped to the actual line length so entering 0 0 5 and 1 in three separate cells would produce the same result Note that a section does not necessarily have to be defined to start at a distance of 0 so entering 0 5 10 5 and 20 5 in three separate cells would produce the same result This latter example would be of particular use in creating preliminary models for eventual staged construction uses Q Along reference path For this option the actual distances must be entered at which each section will be positioned along a reference path For bridge engineering use this equates to entering chainage values Values are entered as absolute and not relative distances Note that a section does not necessarily have to be defined to start at a distance of 0 If a model is defined local to an origin of 0 0 0 the reference path origin the Value of distance at start of path in the Path Definition dialog can be defined to start at say 100 and then entering 100 105 and 110 with reference to the path assignment would position sections at the start of and incrementally along the lines selected Examples are provided of distance types See Distance Types and Methods of Assignment Table related buttons LI The Symmetric section check box copies any
84. ensuring correct alignment of influence attributes along all spans of a bridge deck when those spans are formed of multiple straight lines arcs or any combined sequence of these two feature types in order to describe the carriageway shape Note that a longitudinal direction definition must always be correctly defined for influence analysis Transverse This is assumed to be orthogonal to both longitudinal and vertical directions This is currently only used for influence analysis Section Property Calculation Cross sectional geometric properties for use with line beam models can be calculated for E E E E Standard sections a range of commonly used section shapes Arbitrary sections any user defined cross sections that are drawn in LUSAS Modeller Precast beam sections with and without a concrete slab Box sections for both simple and complex box sections with and without an internal void 274 Chapter 6 Standard Section Property Calculator Standard section property calculators are accessed from the Utilities gt Section Property Calculator menu item The following sections are supported LJ Rectangular solid section equal and unequal thickness LJ Rectangular hollow section equal and unequal flange web thicknesses Q Circular solid section Q Circular hollow section LI I section equal and unequal flanges haunch section LI T section LI L section single and double back to back LIC section lipp
85. full details of the data syntax supported by LUSAS Solver e Available in PDF and printed form Modeller Reference Manual Theory Manuals Volume 1 and 2 e These contain more detailed theoretical information for the more experienced user They cover topics specific to LUSAS and where appropriate list references to other publications The topics covered include e Analysis procedures including linear nonlinear dynamics eigenvalue extraction modal analysis all forms of field analysis fourier analysis and superelement analysis e Geometric nonlinearity e Constitutive material model formulations e Loads and boundary conditions with particular reference to general load types constraint equations slidelines and thermal surfaces e More complex post processing calculations including nodal extrapolation and calculation of Wood Armer reinforcement moments e Element formulation theory e Available in PDF and printed form Verification Manual e A manual of LUSAS testcase examples benchmarked against known solutions e Available in PDF form only CAD Toolkit User Manual e Describes interfaces to LUSAS involving the use of external pre and post processing packages e Provided in PDF form only LUSAS Programmable Interface LPI e Provides information for application programmers wishing to customise the LUSAS environment or interface LUSAS with other applications e Provided in on line help format only This can be
86. ill conditioning problems A force equal to the large mass is applied at the support point thereby inducing a unit acceleration response LARGE MASS 166 kg Joint Element Modal Dynamics Results Types LI Frequency domain response Harmonic or forced response analysis is used to investigate the effects of structural resonance where structures are forced to vibrate harmonically at or near their own natural frequencies Solution of the harmonic response problem as a modal analysis avoids the need to perform a full transient dynamic analysis Simultaneously applied excitations may contain phase differences LI Time domain response impulse or step by step dynamics to dynamic excitation The forcing function and the consequent response of a structure are defined in terms 338 Chapter 8 of time histories The Fourier transform of the time domain gives the corresponding quantity in the frequency domain Q Spectral response analysis An analysis in which a defined response spectra for a generic earthquake ground motion is used to estimate the maximum displacement or pseudo velocity or acceleration during the earthquake without the need for direct integration of the model over the complete duration of the event Dynamic excitation is applied to all the supports simultaneously A response spectrum curve defines the magnitude of excitation If the damping in the response spectrum curve differs from that defined for the model a damping corre
87. in segment length when meshing a line specific heat A thermal material property associated with the resistance to temperature change It is the equivalent of inertia in a structural analysis spectral curve Input curve for a response spectrum spectral response An analysis in which a response spectra for a generic earthquake ground motion is used to estimate the maximum displacement or pseudo velocity or acceleration during the earthquake without the need for direct integration of the model over the complete duration of the event spherical path See arc length method spline A type of line defined between points using a mathematical expression spring element See joint element SRSS method A method used in spectral response analysis where design displacements stresses and forces are evaluated as the square root of the sum of the squares See also CQC method start up file A file used to convey system set up information to an application on start up or at pre defined points during its execution The LUSAS start up file can contain system parameters and valid LUSAS commands These files are run when the program is initiated and when a new model is loaded or initialised starting iteration vectors The number of terms used as initial guesses in an eigenvalue extraction See a so Iteration static An analysis which assumes that the response to the load is immediate because inertial effects are ignored 463 M
88. interface joint meshing the stiffness and yield force defined in the joint properties should be defined per unit length when using interface joints assigned to lines or per unit area when using interface joints assigned to surfaces e Initial gaps are measured in units of length for translational freedoms and in radians for rotational freedoms 189 Modeller Reference Manual e Smooth Contact If an initial gap is used in a spring then the positive local axis for this spring must go from node 1 to 2 If nodes 1 and 2 are coincident the relative displacement of the nodes in a local direction d2 d1 must be negative to close an initial gap in that direction e Frictional Contact If an initial gap is used in a spring then the positive local x axis for this spring must go from node to 2 If nodes 1 and 2 are coincident the relative displacement of the nodes in the local x direction Ox2 6x1 must be negative to close an initial gap e Both Smooth Contact and Frictional Contact joints can be used for lift off or hook contact by using appropriate stiffnesses gap and yield force Support Conditions General Support conditions describe the way in which the model is restrained A support attribute contains information about the restraints to be applied to each degree of freedom There are three valid support conditions LI Free F the degree of freedom is completely free to move This is the default Q Fixed R the degree of freedom i
89. is at its nearest 19 Modeller Reference Manual Nearest pair to reference position defines Points on each line at the intersection nearest to the defined reference Point Limit distance between points only creates Points at intersections that are within a specified distance Allow extended lines will create Points at the intersection of the extension of the selected Lines LI By Projection Defines a Point at the perpendicular projection of a selected Point onto a selected Line or Surface LI By Extension Defines a point at the extension of a selected Line The extension may be defined as a parametric or actual length Q Make Planar moves the selected points onto a plane defined either as an offset from an orthogonal plane or onto a plane defined by 3 coordinates or as a best fit to the selected points A local coordinate may be used to define the orthogonal axes if required Lines Lines define the edges of the model They are stored in the database by referring to their lower order Point features and in some cases a map which defines their internal shape The line types available are Q Line defined by two Points UL Are Circle defined by two Points and a Line map Q Spline defined by two or more Points LI Lines may also be created by Splitting lines Additionally these other lines may during the modelling process be created as a result of editing the geometry Q Elliptical Arc Ellipse LJ Compositio
90. is used to calculate all values but the linear interpolation method is also available The visualisation of tapering sections on the Geometric Line dialog is for information only Only by selecting the Visualise button will a correct representation of the relative arrangement of both sections be seen incorporating any alignment options specified on the main dialog When modelling varying cross sections with constant section beam elements care should be taken to ensure that sufficient elements have been assigned Greater than 8 elements should be used for small variations in cross section along the length of the geometry to which the section has been assigned and considerably more elements should be used for larger variations 150 Chapter 6 e More complex tapering can be achieved using the Multiple Varying Section facility e Models created prior to version 14 2 will not have any fibre locations data stored for each beam However the relevant fibre location data can be added automatically for these models by double clicking on each Geometric line entry in the Treeview and re selecting the same section size from the appropriate sections library e Double clicking on a geometric line attribute name in the b Treeview allows editing of beam section information Geometric Surface Properties Geometric attributes are defined for surfaces using the Attributes gt Geometric gt Surface menu item Thickness T n LI Struct
91. kept in contact allowing frictionless sliding contact without lift off to be modelled The tied slideline option allows meshes of differing degrees of refinement to be connected without the need of a transition zone between the meshes Slideline Properties LI Master slave stiffness scale Controls the amount of inter penetration between the two surfaces Increasing the scale factor will decrease the amount of penetration but may cause ill conditioning Recommended values are e Implicit static solution 1 0 e Explicit solution 0 1 e Tied slidelines 100 to 1000 Slideline stiffnesses are automatically scaled at the beginning of an analysis if the average master slave stiffnesses differ by a factor greater than 100 This is to account for contact between bodies that have significantly different material properties This facility can be suppressed via File gt Model properties gt Attributes and selecting Suppress initial slide surface stiffness check L Coulomb friction coefficient Defines the coefficient of friction between contacting bodies for Coulomb s law Only applicable for friction slidelines Q Zonal contact detection parameter This defines the region around a node within which a search for contact is conducted The size of the region is a factor of the size of the overall model the model is projected onto the global x y and z axes and the largest projection is used as a reference For further information refer to the Th
92. known as natural frequency analysis See also direct integration eigenvalue analysis explicit dynamics eccentricity A geometric property of a thin beam plate or shell that allows an offset of properties from the nodal line such as any applied supports or loading For thick beams an eccentricity is defined as an offset edit To change the contents of an existing dataset Properties from the edited dataset will automatically be used when the model is next tabulated See also define edge collapsing Edge collapsing is the process of removing elements with very short sides or acute angles by merging them with neighbouring elements This is particularly useful when meshing models imported from CAD 434 Index eigen mode The natural frequencies of a structure are calculated using an eigenvector analysis The mode shape is known as the eigen mode See also eigenvector mode shape eigenvalue The frequency or load factor magnitude corresponding to the displacement shape resulting from an eigenvalue analysis Eigenvalues can also be described as the roots of the characteristic equation of the system The number of eigenvalues relates directly to the number of equations of motion of a system The square root of the eigenvalues are the resonant or natural frequencies eigenvalue analysis Extraction of natural modes of vibration of a structure Also known as natural frequency analysis dynamic analysis eigenvalue buckling The proc
93. large residuals However in sensitive geometrically nonlinear problems near bifurcation points it can sometimes be necessary to ensure that large residuals are completely eliminated LJ Root Mean Square Residual Norm is the square root of the average of the squares of the residual forces and is generally more applicable than the above but is still dependent upon the units being used LI Displacement Norm is the sum of the squares of all the iterative displacements as a percentage of the sum of the squares of the total displacements and is a useful measure of how much the structure has moved during an iteration Being a scaled norm it is not affected by units but convergence is not guaranteed Typical values of slack and tight norms are 5 0 1 0 and 0 1 0 001 respectively 290 Chapter 7 Q Residual Force Norm is the sum of the squares of all the residual forces as a percentage of the sum of the squares of all the external forces This is the most versatile of the five criteria Typical slack and tight values are 10 0 5 0 and 0 1 0 00001 respectively LJ External Work Norm is the work done by all the residuals acting through the iterative displacements as a percentage of the work done by the loads on iteration zero of the increment Since all freedoms are considered it is very versatile the default displacement and force norms consider only the translational freedoms However it should be noted that a minimum detected poten
94. lie within that specified within the load curve a zero load factor will be applied e Only line variations with distance type Actual can be used for defining load curves Evaluating a Load Curve Load curves and variations may be viewed using the Graph Wizard Case Study Pressurisation of Tanks with Multiple Load Curves Two tanks are to be pressurised at different stages of a nonlinear dynamic analysis This will be achieved using two different loadcases and two load curves to vary the loads individually The following procedure outlines the steps required 1 Use the Utilities gt Load Curve menu item to define two user defined load curves which give the correct pressure variation with time Note that the time is always from the start of the analysis 2 Use the Attributes gt Loading gt Structural menu item to define a face load attribute containing a unit pressure load Note that the pressure value in the load definition will be multiplied by the load factor used on the load curve associated with it E F 3 Assign the face load to the features in the model selecting the appropriate load curves for each tank The accompanying diagram shows a 2 schematic of the tanks under internal pressure with their corresponding force versus time graphs 4 To set the size and number of time steps right click on Loadcase 1 and choose Controls gt from the context menu Pick Nonlinear and Transient and on the dialog switch on the Time
95. loaded into memory and is available even when another application is active Also known asa TSR menu bar The area at the top of the main LUSAS window where pull down menus are accessed merging Similar features may be merged to give common definitions Whether a feature is successfully merged with another will depend on the closeness of both members and the attributes assigned to them mesh The discretisation of a body into small finite elements whose individual behaviour can be predicted 448 Index mesh dataset A dataset containing details of element discretisation mesh density A term used to describe the relative numbers of elements in a finite element mesh A dense mesh has more elements than a less dense or coarse mesh Also Known as mesh refinement mesh lock The act of preventing a mesh from being updated until it is unlocked Locking a mesh stops commands such as visualisation of loads and supports from forcing a re mesh mesh objects Nodes edges and faces of an element which itself is a mesh object too mesh only modelling Models comprised of nodes and elements only with no geometric feature types such as points lines surfaces or volumes message window Messages are displayed in a scrolling message window mirror A form of transformation in which the model can be duplicated across a mirror plane Mindlin plate These are thick plates which include shear deformation effects See also iso
96. locked into the structure in its initial configuration resonance The amplification of displacements occurring when the frequency of applied loading and natural vibrations coincide or are similar restart file A file containing the relevant parts of a LUSAS analysis database that will allow an analysis to be restarted from a previously converged situation restaint See Supports resultant See stress resultant results calculator See calculator 458 Index results dataset See graph dataset results file See plot file retained freedom A term used to describe master and slave freedoms used in a Guyan reduced eigenvalue extraction reverse To reverse the orientation of a line surface or volume feature See also cycle ribbed plate A 2D high performance incompatible membrane element Takes into account both membrane and flexural deformations Transverse shearing effects are ignored Designed to be used in conjunction with ribbed plate beam elements rigidity matrix A matrix of material constants that relate stress resultants to strain See also modulus matrix round off See diagonal decay RU RL loading Light standard rail loading similar to HA HB rubber A hyper elastic nonlinear material description with approximately constant volume characteristics ruled surface A surface which has at least two opposite lines that are straight The special case of spherical surfaces are also consid
97. many loadcases in parts The loadcases from the separate results files may then be subsequently enveloped or combined Basic Combination Example 327 Modeller Reference Manual LOAD CASE 1 HA amp KEL upper RESULTS FILE 4 STRESS CONTOURS OF hax 1 0 x Loadcase 1 71 0253 50 575 50 7324 41 55 30 4394 20 2929 10 1465 o 10 1465 Wlas 1257 at Node 127 Min 78 75 at Hode 196 LOAD CASE 2 HA amp KEL lower 1 0 x Loadcase RESULTS FILE 1 STRESS CONTOURS OF hie 71 5925 51 3651 51 1375 40 9101 30 568525 20 455 10 2275 o 10 2275 hiaz 1423209 at Hode 156 Min 7896 at Node 190 Combination 3 STRESS CONTOURS OF Mis Combination 07 GDS 76 4405 55 5204 54 6003 43 6003 32 7 00 21 5401 10 85201 E hhax 2 347 at Node 42 Min 95 96 at Hode 190 328 Chapter 8 Smart Combination Example el Loadcase 1 Dead Load Loadcase 2 Live Load Smart Combination Dead Load 1 0 Permanent Factor amp 0 0 Variable Factor Live Load 0 0 Permanent Factor amp 1 0 Variable Factor smart Combination Max Most Adverse Hogging smart Combination Min Most Adverse Sagging For details of smart combination calculations see Appendix A 329 Modeller Reference Manual Enveloping Example Individual Loadcase Bending Moment Results _Loadcase 1 le a m Loadcase2 je Coe Loadcase 3p Loadcase je o mMM gt R Maximum Enveloped Bending Mo
98. maximum and minimum principal stress directions and relative magnitudes In LUSAS the vectors are colour coded to indicate sign See also vector plotting displacement vectors print file A text file to which information can be printed from LUSAS product moment of area See also first moment of area second moment of area program A series of instructions in a form acceptable to a computer Also known as application pseudo nodes Dummy nodes created at element edges when a slice is cut in LUSAS Results calculated at these pseudo nodes are used to contour the slice 456 Index pseudo time A numerical time quantity used in a creep analysis pull down menus Cascading menus may be pulled down from the main menu bar to pass instructions to LUSAS quadrature Numerical usually approximate evaluation of an integral for example Gauss Newton Cotes quarternion A quantity consisting of a scalar and vector component which defines a rotation in 3D space A normalised quarternion is sometimes referred to as an Euler parameter quasi harmonic A name for the governing field equations used in thermal or seepage analyses radiation The energy emitted by bodies as a consequence of their temperature See also convection conduction radio button When several parameters are mutually exclusive they may be presented in a dialog box as a series of radio buttons They are signified by diamonds or circles and when
99. may be applied to relatively stiff structures to estimate the maximum load that can be supported prior to structural instability or collapse LI Stiffness analysis Used to perform an eigenvalue analysis of the stiffness matrix at a selected stage of an analysis This facility may be used in conjunction with a nonlinear analysis to predict structural instability or bifurcation points during a geometrically nonlinear analysis LI By including Modal Damping the overall damping factors for each mode can also be printed as a table in the LUSAS Solver output file These values may then be used in a dynamic or spectral harmonic IMD analysis if desired Solving an Eigenvalue Problem Solving an Eigenvalue problem requires setting the Eigenvalue control properties for a particular loadcase In LUSAS the following methods for eigenvalue extraction are available described below LI Subspace Iteration Jacobi and QL solvers The objective of the subspace iteration algorithm is to solve for a specified number of the lowest or highest eigenvalues and corresponding eigenvectors LJ A Guyan Reduction eigenvalue analysis may also be performed in conjunction with the subspace iteration method LI Inverse Iteration with Shifts The inverse iteration method allows the computation of the eigenvalues and corresponding eigenvectors within a specified eigenvalue range of interest LI Lanczos Derived from the same principles as the subspace iteration method b
100. model Annotation polygons may be re selected if a model is reloaded at a later date in order to create a slice at the same location Slice sections can also be created using surfaces that are created at slice section locations These surfaces do not have to surround a model they must simply be defined in the orientation of the cutting plane required To use a saved cutting plane or a surface defining in cutting plane instead of indicating the cut using the cursor the annotation polygon or surface should be selected before choosing the Utilities gt Slice through 3D menu item and By selected polygon surface option Notes e No results visualisation or printed results for slices are available unless the Display on slice s option has been selected on the Contours and Values properties dialogs or on the Print Results wizard dialog 353 Modeller Reference Manual e 3D sectioning slicing is only available for 3 Dimensional solid models For surface models refer to Graph Through 2D below e A slice can form the basis for a line section using Graph Through 2D to graph results along a line through the centre of a three dimensional solid Manipulating The Slice E 8 la aizel E 484 Concrete_Dam mel Once a 3D slice section has been defined a slice exists as a group in the L l Treeview and may be Ef Slices manipulated using the View gt Group menu item or a NVISIOE from the group s context menu For more detail
101. number of Variable loadcases to consider the remaining negative load effects will only use the permanent factor The number of load effects summed is restricted to the number of loadcases specified and the other loads are also discarded The loadcases used are the most adverse for example the most negative for min combination and all other load effects assembled are discarded Also with the variable loadcases set to four the min combination will include only negative load effects all positive load effects are discarded 394 Appendix A Nodal Permanent Variable Factor used for maximum Factored nodal Loadcase result factor factor combination results Temperature 5 0 7 0 8 0 7 0 8 5x1 5 7 5 Used Wind 5 0 7 0 8 0 7 5x0 7 5 Not used Settlement 10 0 7 0 8 0 7 0 8 10x1 5 15 Used Live load 1 20 0 7 0 8 0 7 0 8 20 x 1 5 30 Used Live load 2 15 0 7 0 8 0 7 0 8 15 x 1 5 22 5 Used Live load 3 10 0 7 0 8 0 7 10x0 7 7 Not used Live load 4 5 0 7 0 8 0 7 5 x 1 5 3 5 Not used Smart combination Min 75 Smart Combination Case 5 Consider a node where short term load effects are of mixed sign with the Loadcases to consider set to four and the Variable loadcases set to one The permanent and variable load factors will only be considered for the number of loadcases specified as the number of Variable loadcases to consider The factors will be added together based on the nodal result being adverse The remai
102. of 3 defined varying sections assigned to T selected Ines Multiple line beams assigned a single multiple varying section line attribute with reference to a path with starting distance specified for clarity beam line has been visualised at top of section When defined section distances do not map exactly to lines on a model In defining distances at which sections will apply and then assigning geometric line attributes containing those sections to lines on a model with reference to a path there may be occasions where the set of defined sections are too short for the assigned line or lines or too long 160 Chapter 6 LI If a set of defined sections are too short for the assigned line or lines the geometric line attribute will stay assigned to all line or lines selected but no visualisation fleshing will take place on any line in a set of lines that does not have a complete line attribute assigned Any attempt to solve a model containing such assignments will also produce tabulation errors UL If a set of defined sections are too long for the assigned line or lines fleshing of the section shape will take place but only for the length of line or lines that was selected and no tabulation errors will occur as a result when solving the model Modelling examples Use of the multiple varying section facility enables simple prototype and assessment models of bridges formed of tapered box sections to be created in a very straightforwa
103. of the more common queries and their typical solutions as listed below Eigenvalues are missing A Sturm sequence check is performed by default to indicate the number of modes which may be missing LI Check for Warnings or Errors Check the output file for any other warnings or errors There may be diagonal decay or pivot warnings that will indicate node and element numbers and help to identify any suspect areas of the mesh LI Iteration Vectors Increase the number of starting iteration vectors If any of the modes are close together the default magnitude for this parameter may not be sufficient to allow accurate resolution in their extraction LI Convergence Tolerance Tighten the convergence tolerance since again some modes may be close together This would normally also require an increase in the number of iterations permitted L Convergence Achieved Ensure the solution converged correctly If not then increase the number of iterations permitted Q Mesh Refinement Increase the mesh refinement of the model in order to increase the number of degrees of freedom in the structure to simulate all the modes expected LJ Symmetry Taking advantage of symmetry in an eigenvalue analysis may cause the inadvertent omission of several eigenvalues as a result of the corresponding symmetry supports restraining certain non symmetric eigenmodes LI Increase Shift If a shift has been used to eliminate rigid body motions when analysing unsupported st
104. of the tree frame displays each model window currently open and shows the view layers contained in that window LI Window Properties Double clicking in a window or right clicking in a window with no selection will display the properties of that window The Window Properties can be altered as required Saving a View A view of a model may be saved with the current settings for future use using the Window gt Save View menu item Any new window is based on the default view Therefore if a view is saved with the name default all new windows are based on this view The view name Factory default cannot be changed and is the default view when the system is installed The following settings are saved LJ Rotation The current rotation consists of a vector and an origin as specified on the View tab of the Window properties Q Layers The window layers contained in the Treeview LI Colours The colourmap as used for plotting results contours LI Page size amp borders The page size and border setting as defined from the File gt Page Setup menu item Q Pen Library The pen library referenced every time a item is drawn All the above settings are saved The choice of which to apply to a new or current window is made when a view is loaded Pen Library The choice of colour for various operations is linked to the Pen Library The Pen Library contains twenty pens each numbered each with a colour style and thickness that may be set if desired
105. on slice sections and at SERS GUE slice axis directions Print Properties Print Forces LI Print Properties Displays information about the slice including cross sectional area of the slice centroid and section property data Properties Q Print Forces Displays force and moment information for the slice Group symbols explained A symbol adjacent to each group name in the L Treeview shows the visibility and status of each group When modelling A black dot next to a symbol denotes the current group into which all new geometry will be added when created nig green tick All of the objects in this group are visible tg blue tick Some of the objects in this group are visible red cross None of the objects in this group are visible When a results file is loaded bet green tick green border All of the objects in this group are showing results bet blue tick blue border Some of the objects in this group are visible and some are showing results tu green tick blue border All of the objects in this group are visible but only some are showing results Changing the Visibility of Features By default all model geometry is visible providing the geometry layer is present and turned on in the Treeview and providing it is not hidden by another layer but as models get larger it is convenient to temporarily turn off the display of parts of the model 35 Modeller Reference Manual Features may
106. one is clicked all others in that group will be released See also dialog box rate dependent Time dependent material properties Rayleigh damping A form of damping which is constructed from user specified proportions of the stiffness and mass matrix terms See also structural damping viscous damping reaction A force or moment calculated at a support position to counteract any applied loading real number An ordinary number either rational or irrational reference path A route or path through the model that provides a concept of distance from an origin to each point in the model 457 Modeller Reference Manual regular mesh A mesh lying on a regular surface consisting of the same numbers of divisions on opposing lines regular surface A surface defined by 3 or 4 lines hence may be meshed using any meshing technique See a so ruled surface release The act of freeing a beam end rotation Also known as moment end release renumber To change the numbers of features Usually used to rationalise feature numbers into consecutive ascending order residual force A measure of the unbalanced force present in the structure after solution residual norm A LUSAS convergence parameter which expresses the limit of the sum of the squares of all residual forces as a percentage of the sum of the squares of all external forces See also convergence displacement norm work norm residual stress Stresses that are
107. or Fz for example fal Annotation appended to the layer name followed fl Values Fz ForceMoment Thick 3D Bear by the entity type such as ffl Diagrams Fz Force Moment Thick 30 Beam 344 Chapter 8 Force Moment Thick 3D Beam If different component and entities are selected at a later time the layer name in the Layers LE Treeview is updated to reflect the chosen selection Deformed Mesh Plots The deformed mesh may be displayed at any time T for a single loadcase For a structural analysis this f uly WA if is the shape under load whereas for an eigenvalue Natasa analysis this is the shape corresponding to the NTA selected eigen mode ea Q Mesh Scaling is specified as either a PARC NN w at A deformation factor or a deformation p OTT A magnitude The deformation magnitude D TRS specifies the maximum deformation to be i H displayed on the page in millimetres LI Mesh Style The deformed mesh style may TR H be altered as required using wireframe 4 CHE n i solid colour hidden mesh and element eE ri TH effects Te AHH l f GH Comparing The Deformed And The Undeformed Shape Drawing the mesh and the deformed mesh together but in different pens is useful for visualising the deformations Sate SSS RNS See ce ge pna SOS SECS e a a epee eee In the example of the grillage shown the scale of the deformed plot is greatly exaggerated using a scale factor of 10
108. other results 362 Chapter 8 Plotting Contours Values and Vectors for Slidelines For three dimensional analyses contours of contact results can be displayed by selecting Slideline Results as the entity on the Contours dialog The full list of slideline results will then be available in the Component combo Slideline values and vectors can be displayed for both two and three dimensional analyses by selecting Slideline Results on the Values or Vectors dialog With values the full list of slideline results components is available whilst with vectors only Contact and System Forces are available Note When looking at the deformed mesh from a contact analysis the exaggeration factor should be set to 1 0 to avoid a misleading visualisation 363 Modeller Reference Manual Table of Slideline Results Availability Slideline Results components Label ContoursValuesVectorsPrintingGraphing System forces Contact force in system x direction ForceX Yes Yes Yes Yes Yes Contact force in system y direction ForceY Yes Yes Yes Yes Yes Contact force in system z direction ForceZ Yes Yes Yes Yes Yes Resultant contact force RsltForce Yes Yes Yes Yes Yes Gap forces Tangential gap force in local x direction TanGapFrcXYes Yes Yes Yes Tangential gap force in local y direction TanGapFrcYYes Yes Yes Yes Resultant tangential gap force RsltTanFre Yes Yes Yes Yes Gap force normal to contact surface NrmGapForcYes Yes Yes Yes Contact forces Tangentia
109. particularly when the thermal surfaces form an enclosure In this instance an environmental node can be used to model the intervening medium with all nodal areas which are not directly linked to other areas linked to the environmental node The environmental node then re distributes heat from the hotter surfaces of the enclosure to the cooler ones without defining the exact process of the transfer Note Environmental nodes cannot be defined in LUSAS Modeller and must be edited directly into the LUSAS analysis data file if required See the Solver Reference Manual for further information Radiation Options Radiation options are set from the Model Properties dialog Available options are LJ Suppress Recalculation of View Factors in Coupled Analysis Model properties Solution tab Thermal options Turns on off the view factor recalculation The option should be turned on when the radiation surface geometry is unchanged by the 229 Modeller Reference Manual structural analysis This stops recalculation of the view factors LUSAS Solver option 256 Constraint Equations A constraint can be defined to constrain the movement of a geometric or nodal freedom Constraint equations allow linear relationships between nodal freedoms to be set up Constraint equations can be used to allow plane surfaces to remain plane while they may translate and or rotate in space Similarly straight lines can be constrained to remain straight and different p
110. path LI The Distance from reference origin to start of path can be also be entered If this value is non zero the value is added to the distances along the path The orientation of the slice local axes is defined from both the tangent of the path at the location of the slice and the direction that the model is viewed from If the slicing path is in the plane of the screen the positive slice local z axis will be defined by the tangent of the path and the positive slice local y axis will be orientated in the out of screen sense If slicing path is not in the plane of the screen the positive slice local y axis will be defined perpendicular to the path tangent in the path tangent out of screen plane The positive slice local x axis will be defined perpendicular to both the slice local y and z axes Q Options are available for the calculation of the moments about either the Neutral axis or the Path intersection with the slice plane Note For the calculation of beam stress resultants it has to be assumed that plane sections remain plane under the action of the loading The strain distribution over the whole section also is assumed to remain linear The location of the neutral axis can therefore be calculated directly from the areas and stiffness of the contributing materials in the composite cross section see Gere amp Timoshenko Mechanics of Materials 3rd SI Ed pg 301 For the calculation of the neutral axis location the Transformed Section M
111. plot results on amp Q 12 IB composites laminae a particular lamina must be made E strip mdl active Setting a Lamina active shows results for just ao ies that lamina Composites layer information can be seen Geometric 1 and visualised by double clicking on the Laminate i Hiipa stack name and selecting the Visualise button on the ee Loading 1 dialog presented a m Saran i 1 Laminate Stack E3 5 Lamina m Lamina Set Name Active Laminal_symm Direction definition 321 Modeller Reference Manual Results Types There are several different types of results entities available in each results file Full details of the results available for each element type may be found in the Element Reference Manual Each time results are displayed the results entity must be specified Only result entities that are actually contained in the loaded results file are presented for selection The following is a summary of all the results types Structural Analysis Thermal Analysis Q Displacement Q Plastic Strain LJ Potentials Q Stress Q Creep Strain UL Fluxes 0 Strain LI Rubber Stretch LI Gradients LI Loading LI Strain energy LI Thermal Surface LI Reaction Q Plastic work LI Reaction Stress LI Slideline 0 Residual Q Named variables Q Velocity LI State variables LJ Acceleration Notes e Stresses are stress resultants for beams plates and shells 1 e forces for beams and force unit width for plates
112. results from the loadcases using just the permanent factors given for negative load effects and using permanent variable factors for positive load effects The number of load effects summed is restricted to the number of loadcases specified The loadcases used are the most adverse for example the most positive for max combination and all other load effects assembled are discarded Factor used for Nodal Permanent Variable maximum Factored nodal Loadcase result factor factor combination results Temperature 5 0 7 0 8 0 7 5 x 0 7 3 5 Used Wind 5 0 7 0 8 0 7 5 x 0 7 3 5 Used Settlement 10 0 7 0 8 0 7 10 x 0 7 7 Not used Live load 1 20 0 7 0 8 0 7 20 x 0 7 14 Not used Live load 2 15 0 7 0 8 0 7 15 x 0 7 10 5 Not used Live load 3 10 0 7 0 8 0 7 0 8 10x1 5 15 Used Live load 4 5 0 7 0 8 0 7 5 x 0 7 3 5 Used Smart combination Max 4 5 Smart combination Min will assemble results from the loadcases using just the permanent factors given for positive load effects and using permanent variable factors for negative load effects The number of load effects summed is restricted to the number of loadcases specified The loadcases used are the most adverse for example the most negative for min combination and all other load effects assembled are discarded 392 Appendix A Factor used for Nodal Permanent Variable maximum Factored nodal Loadcase result factor factor combination results Temperature 5 0 7 0 8 0
113. sequence and occupies a region that is 16 pixels wide and 15 pixels high The bitmap is named userToolbar bmp case sensitive and can be found in lt LUSAS Installation Folder gt Programs Config folder 123456789 T A fF Bg User toolbar button bitmap image as supplied Example of user defined toolbar button bitmap image It is recommended that the supplied file is copied and renamed to userToolbar_supplied bmp prior to making any changes to this supplied file Changes made to the button images will be seen when LUSAS Modeller is next run 47 Modeller Reference Manual 48 Chapter 3 Chapter 3 File Types LUSAS File Types LUSAS uses a significant number of different file types for a varied range of purposes The file types covered are summarised below LI Model Files mdl are created by LUSAS Modeller and are used to store all model definition information Q Analysis Data Files dat are created by LUSAS Modeller during the tabulation phase They contain the data required by LUSAS Solver to perform an analysis Q Solver Output Files out are text files which are created by LUSAS Solver They contain an echo of the input data details of any errors or warnings which have occurred during the analysis and tabulated results if requested LI Solver Results Files mys are created by LUSAS Solver and contain all of the analysis results for access by LUSAS Modeller Results files are also referred to as plot files LI Modeller
114. set of Surfaces in selection etc 93 Modeller Reference Manual Q By Extrusion Enables a Volume to be defined by extruding a specified distance normal to a selected Surface The positive direction is defined by the Surface normal unless an additional Point is selected Extrusion can be towards or away from the specified reference Point Coalescing Volumes The internal Surfaces from a Volume model may be removed by coalescing Volumes This will result in a model with fewer Volumes which may be meshed using Tetrahedral elements Delete Holes When geometry is imported from CAD it may have small holes defined which are of no significance in the analysis These holes may be removed using the Geometry gt Volume gt Delete Holes menu item Delete Voids Voids are cavities in a Volume which do not penetrate the defining surfaces Voids are removed using the Geometry gt Volume gt Delete Voids menu item 94 Chapter 4 Orientating Volume Axes In some analysis types the Volume axes is used to define the material direction The Volume axis may be orientated by the following methods Q Axis to Surface LI Cycle Axes LI Cycle Relative Hollow Volumes Hollow volumes just like normal solid volumes are defined by a set of surfaces However unlike normal solid volumes the defining lines and points of those surfaces do not need to be perfectly merged together Hollow volumes are mainly used when geometry has been imported fr
115. side to use the top button or the right hand side to display other buttons e Holding down the Shift key while selecting will add to the current selection e Holding down the Ctrl key while selecting will toggle an object s selection state e Holding down the Alt key while selecting will additionally select items that intersect cross the selection perimeter e Ctrl A selects everything visible in the current window e You may filter your selection to include only Volumes Surfaces Lines Points Elements Nodes or Annotation by respectively holding down the V S L P E N or A key while selecting e Alt Enter displays the properties of the current selection e If you the hover the cursor over an object a data tip will appear providing details of that object e Pressing Enter whilst a data tip is showing will select the object described 415 Modeller Reference Manual e To Zoom Drag or Rotate the model hold the Z D or R key down whilst moving the mouse e Using the dynamic rotation while holding down the Ctrl key rotates the model in the plane of the screen e Using the dynamic rotation while holding down the Shift key rotates the model about the screen X axis e Using the dynamic rotation while holding down the Ctrl amp Shift keys rotates the model about the screen Y axis e Using the drag tool while holding down the Ctrl key drags the model up and down e Using the drag tool while holding down the Shift key drags the mode
116. slave 137 Modeller Reference Manual LI To multiple pairs of features This uses selection memory to define a set of slave features prior to selecting a set of master features Defining and Assigning a Joint to a Single Pair of Features To model a single joint element between a pair of features two points two lines or two surfaces 1 Define a Joint mesh attribute with the chosen joint element 2 Select the first master feature 3 Add the second slave feature to the selection 4 Assign the Joint mesh to the two features Options exist to allow definition of the local axes of the joint element Defining and Assigning a Joint to Multiple Pairs of Features To define joint elements between multiple pairs of features two or more sets of points lines or surfaces 1 Define a Point Line or Surface mesh attribute with the chosen joint element 2 Select the slave features and add them to selection memory 3 Select the master features 4 Assign the joint mesh As the same joint mesh attribute is assigned to both master and slave features a mesh pattern is created between the two features with the mesh definition determining the number of joints generated in the joint interface mesh When using interface meshing the joint elements are automatically created joining all nodes on the master and slave features and each joint stiffness is automatically computed from the representative length or area of the elements on
117. specified corner positions oF he Rotate the view using the Dynamic Rotate button until the Surface can be visualised in 31D 3 Using Attributes gt Mesh gt Surface define a mesh using Thick Shell Quadrilateral Linear elements Specify the spacing as 15 divisions in the local x and 9 divisions in the local y directions Since only one Surface is present in the model the divisions for the mesh can be entered directly onto the Surface mesh dialog 4 With the cursor in normal mode assign the mesh to the Surface by dragging the attribute from the ob Treeview onto the selected Surface 5 To define a patch load that is coincident with the side wall Surface first select the four Points defining the Surface in the order they were defined Choose the Attributes gt Loading menu item and pick the Discrete Patch option Note that LUSAS has selected a 4 node patch and filled the Point coordinates into the dialog 6 The load direction coincides with the global Y axis direction so select Y from the Untransformed Load Direction Specify patch corner load intensity values of 3 3 1 1 respectively 7 The patch definition uses a coordinate system that is coincident to the global Cartesian axis system so the load can be assigned to the Point at the origin Point 1 Assign the load to Point 1 0 0 0 leaving all dialog entries as default and press OK to assign the load Note that the patch is drawn as discrete point loads This is because th
118. stiffness parameter A measure of the current overall structural stiffness Originally unity a lower value indicates a general softening whilst a higher value indicates a stiffening of the structure cursor The device used to pick items from the graphics area and select menu entries The hardware device used to control the position of the cursor is normally a mouse See also cursor selection cursor picking See cursor selection cursor keys See direction keys cursor selection To select an item with the cursor Also known as cursor picking curve See load curve cycle Feature definitions can be rotated or cycled by one or more steps For example a surface may have the definition order of the lines cycled to change the local element axes See also reverse cylindrical axis set An axis set based on a cylindrical form See also Cartesian axis set local coordinate system 430 Index d matrix Matrix of material constants which describe the stress strain or constitutive relationship for a material See also constitutive relationship damage The damage done to a structure is used as a measure of how many loading cycles the structure will withstand before failure Failure occurs when the damage reaches unity See also fatigue log life damage material model A nonlinear material model in which the value of Young s modulus degrades with progressive loading damage threshold The initial stress limit below whi
119. structural damping Specifies the damping of each system mode of vibration via the hysteretic damping factor See also viscous damping Rayleigh damping 464 Index Sturm sequence check A stable procedure which indicates the number of eigenvalues below a given eigenvalue and is utilised to test for missing values See also eigenvalue sub session file Commands written to the LUSAS session file may also be selectively logged to a duplicate file This is useful for creating a short command file of one or two commands during a LUSAS session See also command file subspace iteration Evaluation of the lowest eigenvalues and corresponding eigenvectors is achieved by performing a simultaneous inverse iteration using a set of iteration vectors followed by a projection of the problem matrices onto the subspace formed by these vectors See also Iteration substructure See superelements superelements Permit the finite element model to be divided into smaller more manageable components which are then added together to form the complete structure Individual components are known as superelements or substructures superposition For a linear problem the solution is the same if it is found by adding together two or more individual loads or forcing functions and then solving or by solving for the separate loads or forcing functions and then combining the results or responses The second method is called superposition See also load combinati
120. suitable line mesh of type None to the lines Mesh Utilities Mesh utilities provide the means to query distances between nodes to control the meshing and re meshing of all or parts of a model and to use a defromed mesh as a starting point for a further analysis Mesh utilities are accessed from the Utility gt Mesh menu item LI Distance Between Nodes displays in the Text Output window the relative distance between any selected nodes 136 Chapter 6 LI Show Closest Nodes displays in the Text Output window the distance between the closest nodes of any of those selected To control changes being made to a mesh the following menu items can be used in various inter related ways LI Mesh Lock Disables automatic remeshing of a model and prevents any changes to a mesh being made LUSAS automatically locks the mesh on a model when a results file is loaded because any subsequent mesh changes may lead to the assembly of results in a misleading fashion Mesh changes involve renumbering or reorientation of elements and results are associated with node and element numbers Therefore results requested after a remesh without the mesh being locked may appear in the wrong location and in the wrong order in the structure You can unlock the mesh using the menu item Utilities gt Mesh gt uncheck Mesh Lock and Utilities gt Mesh gt Mesh reset LL Mesh Reset Deletes the current mesh and forces a complete re mesh of the whole model usin
121. supported by LUSAS Solver See Solver Reference Manual for details The following analysis type is also available LI Influence Analysis An influence line analysis produces a deformed shape which shows the variation of a chosen function reaction axial force shear force or bending moment at any given point on a structure due to the application of a unit load at any point on the structure In LUSAS the presence of assigned influence attributes on a model determines that an influence analysis will automatically be carried out 280 Chapter 7 About Nonlinear Analysis What is Nonlinear Analysis Linear finite element analysis assumes that all materials are linear elastic in behaviour and that deformations are small enough to not significantly affect the overall behaviour of the structure Obviously this description applies to very few situations in the real world but with a few restrictions and assumptions linear analysis will suffice for the majority of engineering applications The following indicate that a nonlinear finite element analysis is required e Gross changes in geometry e Permanent deformations e Structural cracks e Buckling e Stresses greater than the yield stress e Contact between component parts Three types of nonlinear analysis may be modelled using LUSAS LI Geometric Nonlinearity e g large deflection or rotation large strain non conservative loading LI Boundary Nonlinearity e g lift off support
122. tab of the Model Properties dialog or after geometry definition by selecting the appropriate Lines and Surfaces and modifying the facet density from the Geometry gt Surface gt Facet density or Geometry gt Line gt Facet density menu items 71 Modeller Reference Manual The facet density may be specified either as e Maximum facet length in model units e Maximum deviation d in model units or for Lines as e Minimum adjacent angle in degrees e Minimum number of facets for straight line full arc line and spline line or for Surfaces as e Minimum number of facets for planar surface surface with seam and other surfaces Note that facet density only affects the display of the geometric feature and not the actual geometric accuracy of the model Notes e The display speed is inversely proportion to the number of facets used to define the geometry e The facet density can be visualised by selecting the Facet option on the Geometry Layer properties dialog The facet density display can be restricted to only selected Lines and Surfaces using the Facet only if selected option Using Colour For Geometry The colour in which geometry is drawn may be specified in many ways From the Geometry layer properties specify Colour by Q Own colour An individual feature may be drawn in a pen different from the default geometry type pen The pen is specified on the properties dialog Select the single feature and right click th
123. the axial and radial variations are described by the standard finite element formulation Each term of the Fourier series is analysed individually and the results are then combined to provide the overall solution Fourier elements can be used to model both solid and thin walled structures in particular they offer an ideal method to obtain an initial estimate of the eigenvalues of thin walled structures without the expense of performing a full shell analysis on the complete structure The choice between a full structural discretisation using solid or shell elements and the use of the Fourier element depends upon the number of Fourier terms that are required to accurately describe the load if only a few terms are required then the Fourier element should be considered A Fourier analysis can be considered as a generalisation of the standard axisymmetric analysis The finite element mesh is defined in the XY plane and may be axisymmetric about either the X or the Y axis Loading is applied to the mesh in the standard manner using the loadcase properties with its circumferential variation defined using the curve definition Finally the Fourier components to be computed are input using the Fourier control as part of the loadcase properties Supports are defined in the usual manner with the declaration Axisymmetric Axisymmetric free restrained or spring supports For the n O harmonic the about X axis __ about Y axis spring stiffness per unit radian m
124. the deformable body should have the finer mesh Geometric definition Slideline surfaces can be modelled using linear bi linear segments or as curved contact surfaces using quadratic patches e With quadratic patches the curved contact geometry is constructed from a patch of slideline segments The contact forces are then distributed to the closest segment e The quadratic patches and the curved geometry are set up automatically within LUSAS Solver and no additional specification is required The standard patch configuration consists of two linear segments in 2D and four bi linear segments quadrilateral or triangular in 3D Where a patch definition is not possible the standard linear bi linear definition is used instead e The quadratic patch contact formulation has a non symmetric tangent stiffness matrix The non symmetric solver is therefore set automatically Assigning Slidelines Slideline surface pairs are created by assigning a slideline attribute to selected Lines or Surfaces To assign a slideline 1 Select features that will form the master surface 2 Assign the slideline attribute to these features 239 Modeller Reference Manual An In the Assign Slideline dialog that appears specify Master and the set of features to which it applies The orientation is computed automatically but needs to be specified for shells Top or Bottom Select features that will form the slave surface Assign the slideline attribute to th
125. the local transformed freedoms for displacements etc or according to element local directions for stresses LJ Material direction Transforms results relative to the local element material directions LI Specified angle in the XY plane Transforms results by defining a transformation angle in degrees about the global Z axis The transformation angle is measured in a positive anti clockwise direction from the global X axis The validity of each of the above transformation methods for different results entities is given in the table below Results Entity Stresses Strains Creep Plastic Strains Gradients Displacements Loads Reactions Residuals Velocities Accelerations Potentials Transformation Local coordinate Local element direction Material direction Angle Local coordinate Angle Notes Note that results for beams and joints will always be relative to the element local direction Gives results relative to the element local axes A warning is issued to remind you to ensure a consistent set of directions are available for contouring Gives results relative to the element material directions A warning is issued to remind you to ensure a consistent set of directions are available for contouring Note that beam and joint results will always be relative to the element local direction Cartesian sets existing in the LUSAS Solver data file will be used to automatically create LUSAS Modeller lo
126. the master slave features Notes Joint meshes require Joint material properties to be assigned to them For joints with rotational degrees of freedom an eccentricity must be specified An eccentricity of zero may be specified e The Joint symbol is drawn at the quarter point along the joint nearest to the Master feature e Joint properties should be defined per unit length when assigned to Lines and per unit area when assigned to Surfaces 138 Chapter 6 e Master features hold the mesh assignment data A point can only hold one joint assignment so if multiple joints are to be assigned to a single point that point must be designated the Slave by ensuring it is the second point in the selection e Joints defining spring supports act relative to the initial unstressed configuration rather than that on any previous loadcase This means that to introduce a stiffness to a support in a loadcase during a staged nonlinear analysis relative to the stressed state on the previous analysis you will need to use joints and activate them on this loadcase Examples of Assigned Joints Joint between two points Joint between two lines Joint between two surfaces Joint Local Axis Direction The joint local axis direction is defined when the mesh is assigned Three options are available LI Follow point axes Default selection Adopt the axes assigned from the Local Coordinate if any assigned to the point Any Local Coordinate that has been a
127. the residual structure The stiffness is scaled down by a parameter which can be changed by you In a dynamic analysis the mass and damping matrices are also scaled down by the same factor e When an element is deactivated all loads associated with that element are removed from the system and will not be re applied if an element is subsequently re activated This includes concentrated nodal loads unless the load is applied at a boundary with an active element The only exception to this rule is a prescribed displacement which may be applied to a node on deactivated elements Accelerations and velocities may also be prescribed in a dynamic analysis but this is not recommended e If required initial stresses strains and residual stresses may be defined for an element at the re activation stage e The activation of an element which is currently active results in an initialisation of stresses strains to zero an update of the initial geometry to the current geometry and the element is considered to have just become active The internal equilibrating forces which currently exist in the element will immediately be redistributed throughout the mesh This provides a simplified approach in some cases e The direction of local element axes can change during an analysis when elements are deactivated and reactivated In particular 3 noded beam elements that use the central node to define the local axes should be avoided as this can lead to confusion For suc
128. the same edge of that element must also be fixed or prescribed in the x direction The iterative solver will perform very poorly if there is not enough physical memory for the solution to proceed in memory To guard against this a data check OPTION 51 may be performed as with the direct solvers which will estimate the amount of 311 Modeller Reference Manual memory the iterative solver would use with the specified drop tolerance and choice of preconditioning technique e The iterative solver has limited error diagnostics to warn against ill defined or incompletely specified models If this is suspected the analysis should be run through the standard frontal solver for more comprehensive error diagnostics For further information see the Solver Reference Manual Support with Modelling and Analysis Problems The engineers in LUSAS Technical Support are available to help all clients with a current support and maintenance contract and assist with any problems that may be encountered However to identify the cause of a problem will take time especially if the analysis is large To reduce the time taken in diagnosing input errors the analysis model should be thoroughly checked It is good practice to systematically carry out checks as a matter of course whether or not there appears to be a problem with the solution obtained With the aim of producing a more efficient service some general pointers are given as to what information shoul
129. the support conditions change the loadcase is specified when carrying out the assignment Line supported in X Point automatically supported in X amp Y vA Line supported in Y Lee Notes e On the common feature where support assignments meet the support condition applied is additive e Support assignments on lower order features override those on higher order features e Support conditions cannot be changed for different loadcases in a linear analysis e Support conditions may only be reassigned on a new increment of a nonlinear problem or a new time step of a transient problem All supports assignments from previous increments or time steps which are not reassigned will remain unchanged e Ensure that nodes are not free to rotate when attached to beam elements with free ends For example node 1 in the diagram shown must be 1 2 restrained against rotation as well as displacement otherwise the element will be free to rotate as a rigid body R F e Support conditions may be omitted for eigenvalue analyses provided a shift is used in the eigenvalue control e Assigning a local coordinate to a feature changes the freedom directions of the underlying element nodal freedoms and will hence also affect any global loads applied to that feature Tip Supports which act in tension but not in compression may be modelled using joints or interface meshes 191 Modeller Reference Manual Visualising Support Conditions
130. thermal analysis should be undertaken e In general it is recommended that reading and writing to the data transfer file is carried out at the same point in the analysis This avoids any inconsistency occurring between the time of generation of plastic work and the time of diffusion in the thermal analysis e The thermal softening facility is only valid for nonlinear material models which allow input of a heat fraction The heat fraction takes a value between 0 and 1 and represents the fraction of plastic work converted into heat initialisation of Structural Temperatures LUSAS structural elements allow you to input both an initial temperature field and a current temperature field The structure is not strained if its current temperature field is the same as the initial temperature field variations in temperature defined by the current temperature field from this initial temperature field cause thermal straining The nodal temperatures transferred from the thermal to the structural analyses are read directly into the current temperature field and the thermal strains are then calculated from the difference between the 303 Modeller Reference Manual current and initial fields The initial field in this case is zero everywhere unless it is directly input using the structural temperature loads It is possible to initialise the initial temperature field to the current temperature field which is read from the data transfer file Further data t
131. to enable changes to be made LI Create geometry converts the path into points lines arcs and splines in the Geometry layer LJ Visible turns the display of the reference path on if off Q Invisible turns the display of the reference path off if on LI Visualise at points shows what would happen if the path were associated with other lines on the model and requires explaining in more detail See below 2 0 Chapter 6 Visualisation of reference path at points on the model The reference path context menu option Visualise at points shows the value of the reference path distance for other points in the model It helps to show the validity of using the reference path for other lines in the model and in cases where path labels drawn on these other points did not match those of the reference path it would for some situations draw attention to an invalid transverse direction settings being used Note that currently reference point labels do not update if the underlying geometry is updated 0 0 1 0 2 0 3 0 4 0 5 0 6 0 Reference pah Reference pah Perpendicular orthogonal grid grillage Skewed grid grillage Examples of valid reference path points visualised on the model Influence Attributes Influence type influence direction and displacement direction are used to define an influence attribute for use in an influence analysis These parameters define the type of behaviour of the structure at and around an influence point A Directi
132. to provide a time step increment for use in the viscoelastic constitutive equations If no time control is used the viscoelastic properties will be ignored See Solver Reference Manual for further details 178 Chapter 6 Shrinkage Properties The cure of concrete and thermoset resins is accompanied by isotropic shrinkage which in the case of concrete depends on time temperature and other environmental factors whilst for thermoset resins the shrinkage is normally described with respect to the degree of cure The shrinkage implementation in LUSAS allows an irreversible reduction in volume with time to be modelled The shrinkage of concrete is accommodated using the equations defined in the design code CEB FIP90 and also using a more general routine in which shrinkage is defined using a piecewise linear curve In the general case shrinkage can be defined as a function of time or degree of cure A user facility is also available if required See the Solver Reference Manual for further details Two Phase Rubber Two phase material properties are required when performing an analysis in which two phase elements are used to define a drained and undrained state for soil Notes e Usually the value of Bulk modulus of solid phase is quite large compared to Bulk modulus of fluid phase and not readily available to the user If Bulk modulus of solid phase is input as 0 LUSAS assumes an incompressible solid phase Bulk modulus of fluid phase
133. to work LI By assigning equivalence tolerances to certain features only these features will be equivalenced all others are ignored LI By switching on the automatic tolerancing and accepting the default tolerance all features are equivalenced according to the default tolerance 220 Chapter 6 LI By switching on the automatic tolerancing and assigning other equivalence tolerances to certain features all features are equivalenced according to either an assigned tolerance or the default tolerance Example In this example Surfaces 1 and 2 do not share a common boundary Line therefore the nodes created on their common boundaries will not be joined and must be equivalenced Node 2 will merge with node 1 if it lies within the equivalence tolerance Distance between nodes Equivalence tolerance Using Equivalencing Equivalence attributes are defined from the Attributes menu They are defined as a tolerance which is used to determine whether nodes are considered to be coincident The equivalence attribute is assigned to the features that are to be checked for coincident nodes When an equivalence dataset is assigned to a lower order feature it will search through all higher order features for nodes to be checked For example in order to equivalence two Volumes at their boundaries it is more efficient to assign the equivalence to the Surfaces on the boundaries as a smaller number of nodes need to be checked Automat
134. transformed to set an angle between the global axes and the local axes See the Theory Manual for further information Fatigue Calculations Fatigue calculations can be performed on the results of a linear finite element stress analysis using the total life approach This can be done for continuum elements only The fatigue life may be expressed in terms of the damage that is done to the structure by a prescribed loading sequence or as the number of repeats of the sequence that will cause failure of the structure Contour plots illustrating the fatigue life of the entire structure can be generated The results from fatigue calculations may be viewed using any of the standard plotting techniques Fatigue calculations of the life of a structure are defined from the Utilities gt Fatigue menu item S N Curves S N curves contain the variation in stress strain values with the number of cycles to failure and are defined on a Log Log scale An S N curve is used to calculate the number of cycles to failure for each loadcase Miner s rule is then used to combine the damage for each loadcase to give the total damage to the structure for the specified loading sequence 331 Modeller Reference Manual 4 Cycles Log S toad 3 Cycles Factor 3 Cycles Log N Number of Cycles Notes e Log values are used because of the large variation in magnitude of the input data e If plotting the number of cycles to failure then the number of cycles ent
135. used to numerically model a wide range of engineering problems The following section briefly explains the analysis types available Q Linear Analysis is the most common analysis carried out by engineers and unless specified otherwise LUSAS will perform a linear elastic static analysis or steady state field analysis In these types of analysis multiple loadcases can be accommodated but the model geometry and other boundary conditions cannot be altered Linear analysis assumes that e The loads are applied instantaneously and transient effects are ignored e The loaded body instantaneously develops a state of internal stress so as to equilibrate the total applied loads 2 9 Modeller Reference Manual e The structural response is linear 1 e both the geometric and material response are assumed to be linear For other analysis types control parameters must be specified as properties of the loadcase LI Nonlinear Analysis is used to model significant changes in geometry material or boundary conditions Significant geometry deformation may occur due to the applied loading Changes in material may occur due to material yield Changes in boundary conditions may occur due to the lift off of supports or from changes in contact or frictional behaviour Examples of nonlinear analyses include Creep Analysis and Impact Dynamics LI Transient analysis is used to carried out analyses over a period of time and is progressed in a step by step manner
136. visualised using the Attributes layer in the Er Treeview e Rubber crushing and plastic material attributes cannot be combined 163 Modeller Reference Manual Material Library The more commonly used structural material properties are defined in the material library which is located under the Attributes gt Material gt Material Library menu item The units will default to those chosen on model startup but may be changed if desired Pick the material required from the drop down list and click OK or Apply to add the material properties to the ob Treeview The material properties may then be assigned to the model in the usual way Composite Library The more commonly used structural composite material properties are defined in the composite library which is located under the Attributes gt Material gt Composite Library menu item The units will default to those chosen on model startup but may be changed if desired Pick the composite material required from the drop down list and click OK or Apply to add the properties to the amp Treeview The composite material properties may then be used to define a composite stack or be assigned to the model in the usual way lsotropic Orthotropic Material Isotropic and orthotropic material attributes can be used to specify the following material properties LI Elastic is used to specify linear elastic material properties including Young s modulus Poisson s ratio mass density Orthotropi
137. when a results file only is opened e When a smart combination includes both envelope Max and envelope Min one of the envelopes will be ignored Smart combination Max ignores envelope Min and smart combination Min ignores envelope Max e Spectral IMD loadcases can be combined with other loadcases such as those defining dead and live loads Since spectral loadcases are computed from an eigenvalue analysis the sign of the displacements are always positive but the most adverse effects can be obtained by creating a combination including dead live load and a spectral loadcase both with load factors of 1 and then creating a combination including a dead live load with a load factor of 1 and a spectral loadcase with a load factor of 1 e When combining or enveloping results from multiple results files the mesh must be identical across results files e When envelopes of envelopes or combination results are calculated they are automatically cached Saving the model will also save the cached results to the Modeller Results File so they are available for future use Subsequent access to these results will be similar to accessing results from a single loadcase e Ifthe loadcase IDs which contain the most adverse effects are not required enveloping can be significantly speeded up by placing an envelope within an envelope 326 Chapter 8 Tips e Sometimes due to hardware restrictions it may be convenient to run an analysis which contains
138. wise linear approximation of the function Each reference temperature point is defined in a loading attribute and collectively these attributes define a single loading table The loading table is then assigned to the features as required iF 2 Define a row of Surface features Use an incremental prescribed loading to fix the temperatures at one end of the model Define a convective coefficient function using environmental loading temperature dependent Assign the loading and solve Since the problem is one dimensional the solution may be checked to ensure that the convection coefficient has been correctly interpolated Retained Freedoms Retained freedoms are used to manually define the master freedoms for use in the following analyses Q Guyan reduction eigenvalue analysis L Superelement analysis Retained freedoms are defined from the Attributes menu They contain the definition of the master retained and slave condensed degrees of freedom and are assigned to the features designated as the master nodes 219 Modeller Reference Manual Full Subspace Iteration 20 Masters 15 Masters 10 Masters 5 Masters Equivalencing The equivalence facility is used to merge coincident nodes on otherwise unconnected features If an equivalence attribute is assigned to any features the nodes will automatically be equivalenced after meshing has been carried out There are several ways equivalencing can be set up
139. x div x and y div y The local coordinate set is dependent on the order are specified at load assignment The load intensity in which the coordinates of the patch vertices are is then split into individual load components with an defined associated area of application Search Area Boundary Area of Patch Load individual Load divs x 6 Application divsy 5 Local X Projected Load Local Y Projected Load Loads in the local y projected region dark area Loads in the local y projected region dark area are lumped at nearest loading positions within the are lumped at nearest loading positions within the search area light area search area light area Search Area Search Area Patch load Patch load 214 Chapter 6 Local X and Y Projected Loads Non Projected Load Loads in the local x and y projected regions dark Loads not in the local x and y projected regions area are lumped at nearest loading positions within dark area are lumped at nearest loading positions the search area light area within the search area light area Search Area Search Area Patch load Patch load Full Local X Load Full Local Y Load Loads in the full local x region of the patch dark Loads in the full local y region of the patch dark area are lumped at nearest loading positions within area are lumped at nearest loading positions within the search area light area the search area light area Search Area Search Ar
140. x 1 5 30 Used Live load 2 15 0 7 0 8 0 7 15 x 0 7 10 5 Used Live load 3 10 0 7 0 8 0 7 0 8 10x1 5 15 Not used Live load 4 5 0 7 0 8 0 7 5 x 0 7 3 5 Not used Smart combination Min 51 397 Modeller Reference Manual 398 Appendix B Appendix B LUSAS Solver Trouble Shooting LUSAS Solver Troubleshooting During an analysis warning and error messages may appear in the LUSAS Solver output file An error message will terminate the solution immediately A warning message will attempt to continue the analysis The most common warning and error messages are LI Negative Jacobian Error LI Diagonal Decay Warning Q Small Pivot Warning LI Negative Pivot Warning LJ Zero Pivot Error A description of these Warning and Error messages follows Negative Jacobian Errors A Jacobian determinant is a measure used to give an accurate value of the current area or volume of an element A magnitude of less than or equal to zero will automatically invoke this message and may be a result of one of the following e Incorrect definition of the 2D continuum and plate elements By design LUSAS requires these element types to have an anti clockwise node numbering sequence The order is controlled from the underlying surface feature in which the element resides If this message is output the solution is to reverse the ordering of the surfaces for the elements having these warning messages output Do this in LUSAS
141. yield stress dependency on equivalent plastic strain and is defined as t ag ayprt azp where p is the volumetric pressure T is the deviatoric stress and a0 a1 a2 are pressure dependent yield stress constants Note that if al a2 0 and a0 sy1d2 3 then classical von Mises yield criterion is obtained 182 Chapter 6 hyperbolica2 gt 0 parabolic a2 0 elliptic a2 lt 0 pressure Yield Surface Representation For Different Pressure Dependent Yield Stress Values Notes e Bulk modulus used in tension and unloading see Ist figure The relationship between the elastic bulk or volumetric modulus K and tensile modulus E is given E a by 3 1 2v e Shear modulus The relationship between the elastic modulus values in shear G and E E tension E assuming small strain conditions is given by 2 1 v e Heat fraction coefficient Represents the fraction of plastic work which is converted to heat and takes a value between 0 and 1 e Cut off pressure Should be negative i e a tensile value e Pressure dependent yield stresses a0 al a2 Should be positive The yield surface defined is quadratic with respect to the pressure variable Therefore it can take on different conical forms see 2nd figure either elliptic a2 lt 0 parabolic a2 0 or hyperbolic a2 gt 0 The parabolic form is comparable to the modified von Mises material model while the elliptic form can be considered to be a simplif
142. 153 session file 54 set default 116 setting active composite lamina 248 setting active loadcase 254 setting the environment colours and style 42 shape wizard 96 shear force diagrams 343 shear lag with wide flanged sections 355 short cut menu 9 Simulayt 242 slave degrees of freedom 219 Slave slideline 234 Slice 353 slidelines 234 366 results 361 Sloan optimiser 309 smart combinations 325 389 S N curve 331 soil material modelling 179 solver 314 solver results files 52 solving the model 50 279 Modeller Reference Manual spectral response 299 336 splitting geometric features 81 89 splitting options 89 SSI and SSR loading 198 Standard sections calculation of properties 275 startup templates 44 status bar 10 STEP 67 stiffness analysis 292 STL 68 Stress and strain 198 stress potential 167 stress resultant material model 176 Stress vectors 347 structural damping 223 structural loads 195 Sturm sequence check 295 subreports 383 subspace iteration solver 293 superelements 219 support conditions 190 surface elements 146 surface feature 69 85 Tapering 148 TDET loading 218 TEMP loading 197 temperature loading 197 text output 11 thermal analysis 217 227 302 304 305 thermal restraint conditions 190 thermal surface graphs 365 Thermal Surface Results 364 480 thermal surfaces 227 Thermal surfaces 227 thermo m
143. 7 0 8 5 x 1 5 7 5 Used Wind 5 0 7 0 8 0 7 0 8 5 x 1 5 7 5 Not used Settlement 10 0 7 0 8 0 7 0 8 10 x 1 5 15 Used Live load 1 20 0 7 0 8 0 7 0 8 20 x 1 5 30 Used Live load 2 15 0 7 0 8 0 7 0 8 15 x 1 5 22 5 Used Live load 3 10 0 7 0 8 0 7 10x0 7 7 Not used Live load 4 5 0 7 0 8 0 7 0 8 5 x 1 5 7 5 Not used Smart combination Min 75 Smart Combination Case 4 Consider a node where short term load effects are of mixed sign with the Loadcases to consider set to four and the Variable loadcases set to four In this instance the permanent and variable load factors will only be considered for the number of loadcases specified as the number of Variable loadcases to consider The factors will be added together based on the nodal result being adverse The remaining loadcases are considered using the permanent factor With the number of loadcases to consider set to four only the four most positive resultants will be combined for the Max combination and the four most negative resultants will be combined for the Min combination However by setting the variable loadcases to four only positive results will be considered for the Max combination and negative results for the Min combination Smart combination Max will assemble results from the loadcases using just the permanent factors given for negative load effects and using permanent variable factors for the number of positive load eff
144. 7 of LUSAS The Modeller user interface presents different menu and context menu items according to the type of model in use Cursor selection filters also differ according to the model in use Attribute assignments to different model types Both feature based models and mesh only models require the assignment of materials properties and thicknesses loading and supports etc to geometric features or the comparable and equivalent mesh objects prior to an analysis taking place Note In general whenever an assignment of an attribute to a geometric feature is described in this manual the same attribute assignment can be made to an equivalent mesh object if a mesh only model is being used See the table below for details 15 Modeller Reference Manual Feature based Mesh only Mesh only Mesh only model solid model surface model line model POINT NODE LINE ELEMENT EDGE ELEMENT SURFACE ELEMENT FACE ELEMENT VOLUME ELEMENT Geometric features and their comparable equivalent mesh objects for attribute assignment purposes Feature based geometry models Feature based geometry models are created using the four geometric feature types in LUSAS points lines surfaces and volumes In LUSAS geometry is defined using a whole range of tools under the Geometry menu or the buttons on the Toolbars Feature based geometry models can also be created by importing supported data from third party software packages using the File gt Import menu item
145. 80 Click the OK button Name the variation Hydrostatic variation Click the OK button Using Attributes gt Loading gt Structural menu item define a Local Distributed load entering the Z component as 1 notice that in doing so the additional input button H appears Click on the button and select the variation Hydrostatic variation This will factor a negative unit load using the variation defined in 1 Type Water load as the attribute title Click the OK button Assign the loading to the Surface The applied loading with the variation is visualised as arrows on the model Use dynamic rotate Ne to get a 3D view of the surface If the load is not visualised select the load attribute in the Treeview oe right click and choose Visualise from the context menu Note Visualising attribute assignment requires that the model is meshed 263 Modeller Reference Manual Line Interpolation Variations Line interpolation variations allow values to be varied along a line at any number of distances The distances may be equally or unequally spaced and the interpolation order my be constant line quadratic or cubic Line interpolation variations are defined from the Utilities gt Variations gt Line menu item and selecting Type Interpolation L By Equal Distances defines values at as 4 0 equal distances along a Line The actual value used will be interpolated Linear at the appropriate distance between 4 Divisions these v
146. 9 Modeller Reference Manual Note It is possible to visit this dialog several times to create multiple chapters each of which can have different ordering scope and loadcase choices For example you can create one chapter describing the displacements for the whole of a model and subsequently to create a different chapter describing the stress in a particular group of elements Once created the order of chapters in the report can be modified at any time by dragging and dropping them up and down the Report Treeview Add or Edit an Eigenvalue Results Chapter Model properties Loadcase Basic combination results Eigenvalue results User content Entity v Eigenvalues v Participation factors Mass participation factors vj Sum mass participation factors Significant figures E Decimal places and Chapter name Cancel Help The Eigenvalue results tab of the Chapters dialog is only shown if a model contains eigenvalue results The following eigenvalue results can be selected for listing Eigenvalues Participation factors Mass participation factors Sum mass participation factors The number of significant figures or decimal places for this chapter can be specified The Chapter name can be specified or edited if the default or previously entered name is to be changed 380 Chapter 8 Add or Edit a User Content Chapter Model properties Loadcase Basic combination results E
147. 92 HOMOW V OLUIM GS ciei a iane EN E ENEA REAR a a 95 Shape WV IZANG easa anana TEUNA AEAN aA ENA AAAA AESA 96 Boolean Geometry Construction cccccssseeescesseeescenseeesceasseeecoasseeseoesseeseoanseeseonseessonnnees 97 Geometry From MESM iaeia aaa ae oaea a aao ea eee 98 Moving and Copying Geometry ssssssssnsnnnnnnnnnnnnunnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nnmnnn 99 Merging and Unmerging Features sccceeeeeeeeeeeeeeeeeeeneeseeeeeeseeeeeseeeeeeeneenseeeeeeeenenseeeees 103 Changing Geometry Element Orientation cccssssseeeeeeeeeeeeeeeseeeeenenenseeeeeeeeeeeeeseeeenons 111 CAD Inter tac hing sisipan uddan enaa denea aa KE ARSKA vate aiaa KEA KONUS EEE devtevexdedeeeedaces 114 Chapter 5 Model Attributes coirisiensinas ninnisin enasi sanapari aiaa anan oaaae aaria 115 TEAUF OCG tko y PEE E E E E E E E 115 Manipulating Attributes ssania niania i a aae aa diaa aaia Haa i eaa iaaa iit 116 allas a MOGEl EE E E A E ETE CaS 119 Meshing Surfa S sccocicvcetsccscncensiaiectecesivececnesdesnaneivachenete eaU TROKO KEA SAAP EKAA eVa Raa VLEs NENAS NREN ASAS 124 Meshing VOUS orihinal 124 FIXING Mesh Problems iiarosorsree ae a 136 Mesh UMNE S cigar ea N EET SE Uo Nh ails oa 136 Joint and Interface Elements wc2 lt 2cscencsccss eves ccgteccceceessecceasexduccsrecssgueiecaeecsses2teuefendsecntecxieeeeaieec 137 Non Structural Mass Elements c ccccesseeeccessseeeecssseesecenseeseceaseeeseeaseeeseoaneesse
148. E Results Type Choose the IMD calculation required then set the required parameters Modal Damping Modal damping is the damping associated with the displacements defined by the eigenvectors Its value has no physical significance since the eigenvector contains an arbitrary normalising factor Damping values can be specified explicitly or alternatively can be extracted from the results file LUSAS Solver will only provide modal damping estimates if the relevant damping control data has been included in the eigenvalue analysis By default LUS AS Solver values will be zero Damping is specified using percentage viscous and structural damping values Notes e Structural damping is not used in modal response calculations in the time domain e Structural damping is not applicable in spectral response calculations e All damping ratios are expressed as percentages of critical damping e Modal superposition techniques are not usually appropriate for structures with damping ratios higher than 10 due to coupling between modes Step by step dynamic analysis should be considered in such cases Dynamic Excitation Eigenvalue analyses do not consider any applied load Therefore to carry out a dynamic structural analysis a load must be applied to the structure These loads are specified either in terms of forces or as motion by use of the large mass method L Point Force To set the modal excitation to point force via a node number and a nodal fre
149. E oe senda au eDi AKAA niiden aN ERASER p NAERU Nia aiE 186 Nonlinear US OR carana a T A TaS 186 Joint Properties s aidions R Ea cedcceun avedeuecacvaupuededecsceduceunas 187 Table of Contents SUDPOI CONGILIONS wince ici Ree Re a eee 190 Loading ANniDULES asarira ie eS ee ae Oe eS ole ee oe Lule 194 ASSIGNING Loading soccess ciciccewspe cies tetierevapectece etiere wane a A Era Ea KNEE 194 Structural LOGOS sieves vedicara visi daasssindacevecnducs A Aee OA a N ES 195 Prescribed Lo dS ssis EEEE EAA ee EAE aA EAEE EER ERDAS EESE 200 Discrete Loads EAAS S ASNT EA see eae A eee i E E 201 Defining Discrete Point and Patch LoadS cccceeeeeeeeeeeeeeeeeeeeeseeeeeeeseeeseneeeeeeeeeseeesenens 204 Editing of Discrete Loading Data c scccccseeseeeeeeeneeeeeeenseeeeneaseeeeeeaseeeaneaseeseeeaseeeenoens 207 SEACH ANCAS oiaren aa ENEA ASEN E EEA AANE AAN EI ANNEN a 209 Processing Loads Outside a Search Area ccccccccccesssssesenseeeeeeeeeeeeeeeesseeeneeeeseesseeeeeeeeees 212 Thermal LOAGIAG isscade sous caceda areca a a Eaa Ea aa eee GEER 217 Retained Freedoms cca sisssicc cesses kaiina a iE a Rea E Aa Ea a Aae a aaae 219 EQUIVAIGIICIING voinee aae danean ei sateen ia aa eile edie OE aN aeia Haaa Ea da ENE Aaa EENIAS 220 PS PIOA EAE EE E EE T E E E E E ETE TE EA 222 Delan ONG Paan E E E E E A E T E E E E E EE T 223 Birth and Death Activation Deactivation of Elements cccssccsssessseeeneeeeseseeeeeees 223 Thermal
150. File gt Export menu item Depending upon the export file format chosen the following export options may be available L Current window LJ All L Visible And the following features may be exported L Geometry and Mesh excluding volumes Q Geometry and Mesh including volumes O Geometry Only LJ Mesh only excluding volumes Q Mesh only including volumes 0 Nodes Only 59 Modeller Reference Manual DXF Interface Files The AutoCAD Drawing eXchange Format or DXF file as it is more commonly known can be used to import and export data to and from LUSAS DXF Import DXF files are imported using the File gt Import menu item DXF entities supported by the LUSAS DXF import facility are listed in the table below DXF Entity Imported as LUSAS Feature POINT Point LINE Straight Line 3DLINE Straight Line ARC Arc Line CIRCLE Two arc Lines POLYLINE Spline Line SOLID Straight edged Surface 3DFACE Straight edged Surface TRACE Straight edged Surface POLYGON MESH Multiple straight edged Surface POLYFACE MESH Bicubic Surface EXTENDED ENTITIES Not supported Tip Units and entity orientation can be modified by defining a local coordinate and making this active before importing For example the units may be changed from mm to m during conversion by defining a scale local coordinate with X Y and Z scale factors of 1e 3 The entity orientation may be changed from landscape to portrait with the aid of an XY r
151. For a support condition to be visualised the model must have been meshed Support conditions can be visualised in three ways LJ Arrows Visualises restraints as straight arrows representing translational freedoms and circular arrows for rotational freedoms Spring supports are visualised as spring representations Hinge freedoms are not visualised LI Symbols Places a symbol on each supported node LI Codes Writes a code next to each supported node representing the type of support Notes assigned The code uses F Free R Restrained Fixed S Spring For example a code RRSFFF represents a six degree of freedom node that is restrained in X and Y directions supported with a spring in Z direction and free in all three rotational freedoms For nonlinear and transient problems by default supports are visualised for the active loadcase by combining the assignment in the loadcase history To view the supports assigned to the active loadcase only select the Show only assignments in the active loadcase option on the support visualisation dialog accessed from the attributes layer properties Support visualisation may be drawn using the parent feature colour by selecting the Colour support by geometry option on the support visualisation dialog accessed from the attributes layer properties This is useful to identifying which feature type a support attribute is assigned to visualisation can be toggled on and off using the support visua
152. Further Calculations Q Combinations and envelopes L Wood and Armer reinforcement LI Fatigue analysis of a linear model L Design factors L Composite failure criteria LI Modal analysis L Beam stress resultant from beam and shells LJ Expansion of Fourier analysis results L User defined results Manipulating the Results Model LI Plotting results for groups LI Results on a section through the model LI Slideline results processing Q Thermal surface results processing Visualising and Extracting Results LI Deformed mesh LI Contour plots LI Results as vectors LJ Bending moment and force diagrams LI Concrete crack patterns Q Yield of nonlinear material L Peak values LI Plotting beam stresses L Plotting results for assigned attributes LI Graphing of results Q Animation sequences Q Printing results to the screen or a file LI Generating a Report 318 Further calculations Analysis Results Design factors Modal analysis and shells results Combinations Enveloping Wood and Armer reinforcement Fatigue analysis of a linear model Composite failure criteria Beam stress resultant from beam Expansion of Fourier analysis User defined results model Visualising results Deformed mesh Contour plots Results as vectors Bending moment and force diagrams Concrete crack patterns Yield of nonlinear material Peak values Plotting beam stresses Plotting results for a
153. I Wireframe Displays the mesh as a wireframe using the pen specified Only the visible mesh lines are drawn Click on Hidden parts to draw the hidden mesh also using the pen specified LI Solid Displays the mesh as solid panels using the colour specified Click on the coloured square to change the colour used Q Outline only Draws only the outline of the mesh This is also useful for spotting cracks or discontinuities in the mesh due to features not being merged or equivalenced correctly Mesh LJ Show nodes Draws the mesh nodes Nodes define the vertices of elements LJ Show normals undeformed mesh only Displays the element normal for Surface elements LI Show element axes undeformed mesh only Displays the element axes as a local axis set LJ Orientations only if selected Displays the surface normal or element axes only if the element is selected LI Show activated only All elements are active unless they have a Deactivate attribute assigned to them LI Show quadratic effects Draws quadratic elements with curved edges where appropriate otherwise straight edges are drawn LI of elements remaining Shrinks the elements to the percentage specified LI Colour by Enables the mesh colour to be changed e Mesh colour colours elements in default mesh colour e Group colours elements by group e Connectivity colours element edges by number of neighbours e Element Type colours elements by element type e Normals colour
154. MS DOS carries out the commands in the file as if you had typed them at the MS DOS prompt Used to set up an environment and run a program A batch file has the extension bat See also script file Also known as batch program beam element A straight or curved line element with rotational degrees of freedom used to model frame structures See also explicitly integrated beam numerically integrated beam bending moment diagram A graphical representation of the bending moment results from a beam element drawn along the element Maximum or minimum and end values are accessible See also force diagram beta angle The angle between the element axes and the line axes biaxial A description of a material model in which two axes are considered to determine the material response For instance the biaxial concrete model uses the two principal stress directions See also uniaxial triaxial bicubic patch A surface formed of cubic splines in which the internal geometry is defined as well as the boundary 424 Index bifurcation point A point at which an alternative load displacement path can be taken See also limit point binary file A random access file containing information that is in machine readable form it can be read only by an application body force loading See constant body force boot To start or restart your computer loading the operating system from your hard disk or floppy disk See also hard disk floppy disk bo
155. Model Viewing Shortcuts The model can be rotated zoomed panned and viewed at predefined orthogonal and non orthogonal views using specific cursors or view buttons or by using normal cursor mode in conjunction with specific keys Rotation zoom and pan can also be carried out in other cursor input modes such as when defining lines by cursor or section slicing for example Dynamic Pan Drag Specific cursor Normal cursor key ka Hold down the left mouse button to k D key pan the model k Middle mouse button Note Hold down the key s to restrain the pan for either specific or normal cursor mode about the axis stated X or Shift key Restrain in the screen X axis Y or Ctrl key Restrain in the screen Y axis Dynamic Rotation Specific cursor Normal cursor key ka Rotates the model around various k D key multiple axes Middle Left or Right mouse button Note The model is rotated about its centre unless any part of the model is selected in which case the model is rotated about the centre of the selection Hold down the key s to restrain rotation about the axis stated X or Shift key Restrain in the screen X axis Y or Ctrl Shift keys Restrain in the screen Y axis Z or Ctrl key Restrain in the screen Z axis 411 Modeller Reference Manual Dynamic Zoom Specific cursor Normal cursor key wo Hold down the left mouse button and k Scroll mouse wheel move the mouse k
156. Modeller Reference Manual Version 14 7 Issue 1 LUSAS Forge House 66 High Street Kingston upon Thames Surrey KT1 1HN United Kingdom Tel 44 0 20 8541 1999 Fax 44 0 20 8549 9399 Email info lusas com http www lusas com Distributors Worldwide Copyright 1982 2011 LUSAS All Rights Reserved Table of Contents Table of Contents Chapter 1 Introduction ssiri aaia ai 1 What is Finite Element Analysis 0 cccccceeeeeeeeeeeeeeeeeeseeeeeeeeeeeesaeeeeeeeeeaanaeeeeseeeaeseeeeeseenaaaes 1 Finite Element Analysis with LUSAS cccceeeeeeeeeesseeeeeeeeeseeeseeeeeeeeeseeeeeeenaeeeseneeeeeeeeeees 2 What Help and Documentation is Provided cccceeeeceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeneeeeeseeeeens 3 Chapter 2 Using Modelhef siseisissasiinsa aE E ara 9 Welcome to LUSAS Modeler iiccccsccesccesitericedececuvedtesseccastenteccusnritedecartadden tia ncneecsesersteeenannsks 9 Modeller Licence Seleh issiron Aaaa 13 Creating a New Model cacccccsseteccssnccecceecececscsnscendvanenwceusnieudsnscuckdeannsendenenudecessousstsasssteveuecusedceecs 14 Model TYDES sigre ee ee nee eer ee eee ee cone ee eee 15 Model PROD GTC S saannin ma EEEa EA EEEE EARNE a AAAA EA RE ASENA 18 SUING WIN OW S ocdsesscsccccccccccsesacscedcccteccescdenacc EEEE EEE EAN Oa RENANE 26 SUING AV CNS E E E E castes 27 Selecting Model Features sssini aa aeaa aaa abaa aaan 28 OUDE e E T A 33 Changing the Visibility of Features
157. Modeller with the Geometry gt Surface gt Reverse menu item 399 Modeller Reference Manual Note that in LUSAS Modeller the local axis system of the surface may be viewed prior to tabulation the xy axis system displayed on each surface represents a right handed axis system from which the anti clockwise or positive qz definition may be checked LI Too large a loading increment causing massive deformation of one or more elements This means that the elements are inverting Note that this is only applicable for nonlinear analyses Diagonal Decay Warnings The stiffness matrix is a crucial component in a finite element analysis but it can be poorly conditioned Poor conditioning may result in round off error which is a loss of accuracy in the evaluation of the terms during the reduction process of the solution This in turn leads to inaccuracies in the predicted displacements and stresses LUSAS monitors the round off error by evaluating the amount of diagonal decay present during the Gaussian reduction process This criterion is based on the assumption that initially large diagonal terms accumulate errors proportional to their size As reduction progresses the diagonal term is reduced amplifying the errors until they become a maximum when the diagonal term is the pivot An indication of probable errors may be obtained by examining the change in magnitude of the diagonal term The tolerance threshold above which a diagonal decay w
158. Reference Manual ultiple Varying Serti Hltiple Varying Section Dires medepretation ff Goad ihi esh brs rdia Alongrvference path Faa z Diis espen l Sosedi esh ine Pehkis E Alongraterence path single ph Akyan Vaia ipen a Abn Si sobir ho poii iS Hominy Canna m raria l r Serii 1 1 Beckon 2 2 Seca E39 Marne Sven nF Coe toy Heo Varying section distances defined for assignment of the line Varying section distances defined for assignment to attribute to a single line multiple lines with reference to a path The values entered in the distance cell of the multiple varying section dialog depend upon the intended assignment Examples of each type follow Scaled to fit each line individually In their simplest form multiple varying sections can be defined for assigning to single selected lines on a model Values are entered that will be mapped to the actual line length when the multiple varying section line attribute is assigned to a line or lines on a model For example entering 0 0 333 and 1 or O 1 and 3 in three separate cells would specify a section at either end and at a third point of a selected line that was selected and assigned this geometric line attribute Note that a section does not necessarily have to be defined to start at a distance of 0 so entering 0 5 1 5 and 3 5 in three separate cells would produce the same result This latter example would be of particu
159. Reports context menu in the Report Treeview On the Report properties dialog L The report Title is optional and is used as a title in the exported report O Units for a report are by default the Tile frame analysis same as those of the model However it Units Nmkost 2 ies is possible to prepare a report ina ecimal places different system of units in which case yee all values seen in the report will be A Report add oe new converted appropriately Q It is also possible to control the number Cancel Amb Hep of significant figures and decimal places seen in the report These can also be specified independently for each chapter Q If For all chapters is selected the values for significant figures or decimal places chosen on this dialog will be used throughout the report This option overrides any different values set inside each chapter LI The Report name is the name added to the Report Treeview By default reports are named Report 1 Report 2 etc if no name is specified Once a New Report entry has been added to the Report Treeview selecting the report name and using its context menu enables the adding of chapters to a report mayni Ee viewing renaming or deleting of a report Report templates are saved in the Report Treeview when a model is saved Adding a Report Chapter Model properties loadcase and basic combinations envelopes and smart combination results eigenvalue results and user infor
160. Results Files mrs are created by LUSAS Modeller and are used to store the results cache when the model is saved These files save assembled results and speed up the results processing of combinations If necessary mrs files may be deleted to save disk space Q History Files his are created by LUSAS Solver and contain specified analysis results for access by LUSAS Modeller UL Script Files vbs contain a collection of LUSAS Modeller commands so that when they are replayed a sequence of operations may be carried out automatically Script files can be recorded by LUSAS Modeller or edited directly using a text editor LI Session Files ses are created automatically every time LUSAS Modeller is run They contain a record of all commands issued during a session LI Interface Files dxf igs stp stl def nf allow graphical structural information to be exchanged between LUSAS Modeller and external packages 49 Modeller Reference Manual LJ Command Files cmd are used to import and export models from and to version 13 of LUSAS Modeller where only geometry features supported by version 13 Modeller will be exported Q Picture Files pic bmp jpg wmf allow contents of the Graphics Area to be saved in a standard file format Picture files are used to subsequently display the information or in conjunction with the LUSAS Expose program to create files which may be printed or plotted In addition to LUSAS picture files screen
161. S3 QTS4 TTS6 QTS8 TSMS3 SMI4 NASTRAN BDF and DAT Import Data from NASTRAN Bulk Data Files BDF or DAT dat files can be imported to create a feature based geometry model using the File gt Import menu item or a mesh only model by using the File gt Import Mesh menu item When a file is selected the Advanced button can be used to specify import parameters See Model Types for more information ABAQUS Input File Import Data from Abaqus Input Files inp can be imported to create a feature based geometry model using the File gt Import menu item or a mesh only model by using the File gt Import Mesh menu item When a file is selected the Advanced button can be used to specify import parameters See Model Types for more information ANSYS CDB File Import Data from ANSYS CDB Files CDB can be imported to create a feature based geometry model using the File gt Import menu item or a mesh only model by using the File gt Import Mesh menu item When a file is selected the Advanced button can be used to specify import parameters See Model Types for more information PATRAN Interface Files About PATRAN The PATRAN neutral file contains the full finite element model information The Neutral file is split into two data categories Phase I contains the definition of the geometric entities and Phase II contains all of the finite element node and element information 66 Chapter 3 PATRAN Import PATRAN files are imported
162. Temperatures are transferred from the thermal to the structural analysis and the updated geometry is transferred from the structural to the thermal analysis The analyses may be coupled on the incremental or iterative levels iterative coupling is machine dependent For true full coupling of two nonlinear fields information transfer has to occur on an iteration level within each increment so that in addition to preserving equilibrium of the local thermal and structural fields equilibrium of the combined system is maintained Iterative coupling is essential for strongly coupled systems e g structure to structure contact For weaker thermo mechanical coupling information transfer at an increment level should provide an adequate solution Heat dissipated due to plastic work The heat flux produced due to plastic work can be considered in a coupled analysis In this type of problem the structural analysis is started first and the heat dissipated through elasto plastic deformation is transferred to a thermal analysis The nodal temperatures may then be returned to the structural analysis where they can be used to produce thermal strains and compute temperature dependent properties The following points should be considered when using this facility e The heat flux generated due to plastic work is a function of the time increment over which the work is done For a meaningful solution to this type of problem a dynamic structural and or a transient
163. Volume to enable hollow volumes to be defined LJ Hole Removal Defaults The state of the holes removal defaults may be set from the advanced geometry dialog for all operations involving hole removal operations The defaults control the check box state and may be overridden during geometry creation LI Merge Defaults The state of the merge defaults may be set from the advanced geometry dialog for all operations involving merging The defaults control the check box state and may be overridden during geometry creation LI Drawing defaults faceting The default faceting controls the number of facets used for shading Increasing the number of facets improves the shaded geometry visualisation but takes longer to display See Facet Density for more details Meshing LI Equivalence Defines the default nodal equivalence tolerance used in a equivalence attribute If automatic is switched on equivalencing is carried out automatically for all nodes in the model and no equivalence attribute assignment is required See Nodal Equivalencing for details Q Line Mesh Defaults Sets the default number of mesh divisions on a line and the maximum subtended angle per element for an arc or splines If an element exceeds the max subtended angle the number of divisions on the arc or spline will be increased Q Irregular tet meshing specifies the number of the passes and attempts to be made by the tetrahedral mesh generation when attempting to mesh a volume
164. a 3D nonlinear continuum model may be used see the Element Reference Manual e The lay up sequence is from bottom to top In the case of a shell this will be in the direction of the Surface normal In the case of a solid this will be in the direction of the local z e In cases where surface normals need correcting good use can be made of the cycling facility where feature local axes can be cycled relative to a reference feature to ensure a consistent set of composite material axes e Composite attributes may not include materials that contain variations Draped Solids and Shells This method makes use of the native draping functionality in LUSAS A start point which should lie inside or on the boundary of the surface to be draped can be defined for each ply and the start direction is defined by the x axis of a predefined Cartesian set Prior to assigning a composite attribute of this type to a model a draping surface must be selected or specified The orientations of fibres following the drape are computed by LUSAS and are tabulated with respect to the x axis of the local element axes As with the Solids and Shells option it is essential that the z axis of the volumes to which the composite is to be assigned are consistently oriented See Draping below FiberSIM Solids and Shells and Simulayt Solids and Shells Composite stack details can be read in from an external FiberSIM XMLfile or Simulayt LAYUP file A default fibre volume fracti
165. a nonlinear analysis such as total load factor Strain energy and plastic work Total strain energy or total plastic energy for the elements showing results Previously defined LI Fourier expansion The displacements stresses and strains output from a Fourier analysis are coefficients of corresponding sine and cosine functions The evaluation of 365 Modeller Reference Manual these functions around the circumference of the model is achieved graphically using the Graph Wizard LL Modal expansion Graphs the modal response of a structure to dynamic excitation using the results from an eigenvalue analysis Various results entities may be plotted against a frequency range or sampling time for selected eigenmodes L Load curve Graphs a defined load curve Q Variation Graphs a variation function Q Specified datasets Graphs two previously defined datasets L Thermal surfaces Graphs results along a thermal surface LJ Slideline assigned to line Graphs results along a slideline Note To graph a specified results entity against distance along a slice through a planar structure or on a Slice of a three dimensional solid structures see Graph Through 2D Graph Properties LUSAS uses the Graph Wizard to take you through each step of creating the X and Y datasets and placing them into a graph The graph wizard is started from the Utilities menu The X and Y datasets are then stored in the Utilities Treeview af fl Tower Seismic Resp
166. a small spring element between opposing surfaces of a slide pair when they are within a specified tolerance of any section of the opposing surface The spring controls possible mechanisms in the initial response See a so contact click To press and release a mouse button quickly co rotational Form of geometric nonlinearity in which large displacement effects are related to a set of axes that follow and rotate with the element coarse integration A method of element integration using an alternate selection of a smaller number of Gauss points See also fine integration cohesion A material property of granular materials such as soils or rocks describing the degree of granular bond and a measure of the shear strength colour fill Solid block colours used to represent stress patterns or different mesh views combination See load combination combined line A LUSAS feature made up from a combination of individual connected line datasets It can be used to simplify meshing command bar Part of the LUSAS interface where commands may be typed Displayed from the View menu Also known as command line 426 Index command file Commonly used sequences of commands may be grouped in a file and replayed at any time See also sub session file command line See command bar comments Notes attached to a data or command file for informational purposes only compatible A description of data programs or equipment that
167. accessed from the Start gt All Programs gt LUSAS gt LUSAS Help menu Chapter 1 Glossary e Contains definitions of general terms used in all manuals e Provided in on line help format Included in the Modeller Reference Manual Modeller Reference Manual Chapter 2 Chapter 2 Using Modeller Welcome to LUSAS Modeller LUSAS Modeller is an easy to use Windows based finite element modelling system Creating a Model In LUSAS Modeller two types of models can be created Q Feature based geometry models these comprise geometry features points lines surfaces volumes etc that are created either by using a whole range of tools under the Geometry menu or the buttons on the Toolbars or by importing third party data that is supported Q Mesh only models these comprise only elements and their associated nodes edges and faces and are created by importing only those types of LUSAS or third party data that are supported To both types of model attributeswhich describe the properties of the model materials thicknesses loading supports mesh etc are assigned Attributes are defined from the Attributes menu Once defined attributes are listed in the Attributes ob Treeview Treeview The Treeview is used to organise various aspects of the model in a graphical frame It has six panels each with a Treeview showing Layers ol Groups Lal Attributes S Loadcases LH Utilities s and Reports respectively The Tr
168. acture energy is exceeded Once the fracture energy is exceeded further straining occurs without resistance 185 Mass Modeller Reference Manual Fracture Modes A 2D model has two fracture modes a 3D model has three The fracture modes are L Mode 1 Opening Q Mode 2 Shearing Q Mode 3 Tearing Shear orthogonal to mode 2 Material Parameters Q Fracture energy Measured values for each fracture mode depending on the material being used i e carbon fibre glass fibre LI Initiation Stress The tension threshold interface strength is the stress at which delamination is initiated This should be a good estimate of the actual delamination tensile strength but for many problems the precise value has little effect on the computed response If convergence difficulties arise it may be necessary to reduce the threshold values to obtain a solution Q Relative displacement The maximum relative displacement is used to define the stiffness of the interface before failure Provided it is sufficiently small to simulate an initially very stiff interface it will have little effect LI Coupled The model used for coupling the failure modes Coupled Uncoupled Reversible Uncoupled Origin See the Theory Manual for more details Mass material models are used in conjunction with non structural mass elements to define mass in a structure Mass Properties are input for element nodes in the element local translational x y or z directions or relat
169. al and automatic Where manual and automatic master selection is combined the specified number of automatic masters will be automatically selected from the available free equations The effective selection of the master freedoms is central to the accuracy of the simulated structural response In the selection of the master freedoms the following points should be considered e The master freedoms must accurately represent all the significant modes of vibration e Master freedoms should exhibit high mass to stiffness ratios Hence rotational freedoms are usually inappropriate masters e Master freedoms should where appropriate be as evenly spaced throughout the structure as is appropriate e The ratio of master to slave freedoms should generally be within the range 1 2 to 1 10 e Poor selection of the master freedoms will have a detrimental effect on the accuracy of the solution especially at higher frequencies Sturm Sequence Check When extracting eigenvalues it is important to verify that the computed eigenvalues constitute a continuous set and that intermediate eigenvalues are not missed To do this the Sturm sequence check is invoked this may be switched off by setting the appropriate parameter on the eigenvalue control properties All eigensolutions present are searched for unless you request a smaller number of solutions by specifying the number of eigenvalues note that in this case the eigenvalues returned will not necessarily
170. al coordinates will be ignored 62 Supported IGES Entities Entity 100 102 104 106 108 110 112 114 116 118 120 122 124 126 128 130 140 141 142 143 144 186 Description circular arc composite curve conic arc copious data plane surface straight line parametric spline curve parametric spline surface point ruled surface surface of revolution tabulated cylinder transformation matrix rational B spline curve rational B spline surface offset curve offset surface trimming line of bounded surface trimming line of parametric surface trimmed bounded surface trimmed parametric surface B rep volume All IGES annotation lines and font data is ignored The IGES interface only supports fixed length ASCII IGES files Chapter 3 All curve and surface geometric type entities are translated into LUSAS Modeller Note Only those found in the selected IGES file are displayed in the exclusions list LMS CADA X Files This data format is used to export data from LUSAS Modeller to the LMS Modal Analysis Suite of Software 63 Modeller Reference Manual Q When exporting modal data or element matrices a check for a results file is made If no results are available the moddat parameter is deselected The modes for export dialog is only displayed if modal data is requested LI The mode shapes input dialog will expect the mode shape numbers to be entered in the same manner as the SET MODAL MODES co
171. ally used with feature based models that are not valid are removed or shown greyed out to prevent selection Mesh only menu items such as Geometry gt Element for instance are added to the main menu Context menus may contain different menu items also Additional elements cannot be added to a mesh only model Once imported the number and shapes of the elements are fixed but the type of element may be changed by use of the Change Element Type option on the context menu on the element group name In doing so the number of nodes defining the element topology may be reduced but not increased For instance an 8 noded brick elements may be defined for use on previously defined 20 noded brick elements Notes for mesh only models e The File gt Import Mesh menu item is only available if no Geometry data is present in the Modeller window e Mesh only models cannot contain geometry layer data As a result the option to add a Geometry layer is not accessible e By default when element types from non LUSAS created datafiles are mapped to an equivalent LUSAS elements structural element types are created If the Coupled user interface option has been selected on the New Model dialog prior to a mesh import being carried out then coupled elements will be created during the import process If a different analysis type is specified after the import of mesh data the element types previously used will be changed accordingly e Local coordinate systems
172. alues using the interpolation aces method specified Quadratic 2 Divisions 4 3 4 Multiple Quadratic 4 Divisions Cubic 3 Divisions 4 1 3 4 LI By Unequal Distances defines values 200 1 0 gt sine 7 gt Actual tri at specified distances along a Line i ae oe lt 100 0 5 gt HANENS The distances can be entered as actual 60 03 or parametric values The actual value 4o af 4 0 used will be interpolated at the 46 2 0 appropriate distance between these values using the interpolation method Linear 0 0 3 0 5 1 specified 4 1 3 4 The unequal distance examples below Quadratic as 0 0 3 0 5 show user distances specified by 4 3 4 actual or parametric values indicated in square brackets with a corresponding interpolation value at each position Repeating a distance Discontinuous Linear 0 0 3 0 5 0 5 0 5 0 7 1 4 1 3 2 4 and specifying an additional co coats associated interpolation value will 4 1 3 4 allow a discontinuity in the variation to be defined Linear variations require a minimum of two values Quadratic variations require a minimum of three values and Cubic variations require a minimum of four values to be specified Where 264 Chapter 6 more values are specified multiple interpolation functions are used 1 e if three values are specified for a linear variation two straight line interpolations are
173. alyses because numerical difficulties can occur if a very high bulk modulus is used In these cases a small compressibility 1s mandatory but this should not cause concern since only near incompressibility needs to be ensured for most of the rubber like materials Using Rubber Material Rubber is applicable for use with the following element types currently LY 2D Continuum QPM4M QPN4M 180 Chapter 6 LY3D Continuum HX8M LJ 2D Membrane BXM2 Notes e For membrane and plane stress analyses the bulk modulus is ignored because the formulation assumes full incompressibility The bulk modulus has to be specified if any other 2D or 3D continuum element is used e Ogden Mooney Rivlin and Neo Hookean material models must be run with geometric nonlinearity using either the total Lagrangian formulation for membrane elements or the co rotational formulation for continuum elements The Hencky material model is only available for continuum elements and must be run using the co rotational formulation The large strain formulation is required in order to include the incompressibility constraints into the material definition e Option 39 can be specified for smoothing of stresses This is particularly useful when the rubber model is used to analyse highly compressed plane strain or 3D continuum problems where oscillatory stresses may result in a patchwork quilt stress pattern This option averages the Gauss point stresses to obtain a mean valu
174. am finite element based on numerical integration rather than engineers simple bending theory See also explicitly integrated beam beam element object A LUSAS object is a data entity which is anything listed in the Treeview or a geometric feature such as a Point or Line LUSAS objects can be either edited or have their properties displayed via the shortcut menu right mouse button See also OLE object OK button Will apply the dialog box with the given parameters See a so apply button dialog box on line help See help OLE object A Windows application file that can be linked or embedded into a LUSAS model file OLE is an acronym for Object Linking and Embedding optimisation The process of reducing the frontwidth of a model to the minimum to increase speed of solution and reduce storage requirements See also frontal optimiser options LUSAS options control certain aspects of the analysis They are set in the data file See also data file options box Some LUSAS parameters have only a limited number of possible responses These are gathered into lists and presented as options boxes ordinate The y axis of a graph See also graph dataset abscissa orthogonal cracking Spontaneous or subsequent double cracking whereby both principal stresses violate the cracking criteria and two orthogonal cracking planes develop See a so concrete model ductile fracture non orthogonal cracking cracking orthotropic An or
175. amed Bolt LUSAS also automatically creates groups as part of the general modelling process as slice sections are created or as a result of an analysis when slidelines are present in the model With slice sections groups are created with the group name Slices with each slice section having a group name of Slice 1 Slice 2 etc With slidelines a group named Slideline Results is created containing master and slave group names for each defined slideline Groups are also automatically created when importing data files from other supported third party software applications to create mesh only models In this case groups are named after element or with material references if present in the data file When using LUSAS HPM software groups are automatically created to simplify the modelling of the composite parts as well as the interface surface and other items Uses of Groups LJ Enabling unique components to be identified manipulated hidden or have results plotted only on those features Q Allowing the assignment of attributes to a group in one step The appropriate geometry features will be used if attributes can not be assigned to all geometry types Q Identifying all the features that failed to mesh during any command that invokes meshing See Fixing Meshing Problems L When defining slice sections through a model in order to view the internal arrangement or to plot results Q To allow easy manipulation of master and slave results fol
176. amed group 381 Modeller Reference Manual For example if the selected chapter describes Materials by selecting a Specified group only the Material assignments used in that group will be present in that chapter Loadcase Selection The loadcases combinations or envelopes that the chapter is to report on can be specified by selecting either All Active Specified If multiple loadcases are specified multiple entries will appear in the report Viewing a Report Reports are viewed from the Report Treeview by double clicking on the report name or by choosing the View Report menu item from the report name context menu After a short delay whilst the report data is assembled and formatted a report consisting of all the selected chapters will be displayed inside the third party BusinessObjects Crystal Reports viewer 5 Ch B A fo E fmme masis 2 Tuesday September 29 2009 Date saved 29 Sep 09 10 42 20 Title frame analysis Model Units Nm kz s C Report Units Nm kg s C Model Tiile Simple 2D Frame Model File fame malbysis 2 BusinessObjects Crystal Reports viewer The BusinessObjects Crystal Reports viewer is a linked in third party application that is widely used in industry to present and manipulate report data It has a toolbar that provides the following buttons facilities for viewing manipulating printing and exporting the selected LUSAS model and results data ap oe Fo Ha gt 1 54
177. amic or transient analysis Sometimes the manner in which a structure deforms is not always obvious when comparing its undeformed and deformed shapes and it may be better understood using animation An animation displays a sequence of pictures showing the status of the model or results type for selected loadcases The structure may be animated in two ways Both types of animation are created from the Utilities gt Animation Wizard menu item 368 Chapter 8 LI Active Loadcase for results loadcases only The results from a single loadcase or eigenvector mode shape may be animated according to a trigonometric function sine square or saw tooth A full sine wave 1 to 1 is useful for animating mode shapes obtained from an Eigen analysis while a half sine wave 0 to 1 is useful in animating a static load Q Load History animates chosen model or results loadcases producing a animation frame for each The content of the animation sequence is defined by the contents of the current window when the Animation Wizard is started For example to animate contours add a contour layer to the current window prior to running the animation wizard i4LUSASI Notes If contours are to be included in an animation it is useful to fix contour levels across multiple loadcases using a global or manual scale before creating the animation sequence Setting the contour levels for the highest level of loading will fix contour levels on each screen of th
178. an external influence Excitation is often associated with dynamic loading execute To carry out an instruction or perform a task explicit dynamics High velocity dynamics where the rate of loading is high compared to the natural frequencies of the structure being analysed Explicit problems are classed as wave propagation problems where the behaviour of the wave front dominated by high frequency components is of engineering importance See a so impact implicit dynamics explicitly integrated beam A beam element based on engineers theory of simple bending Also known as engineering beam exploded view Mesh plots may be viewed with the element vertices moved towards the centroid of the element by a given amount exaggeration factor extension A three character set that follows a filename The extension clarifies the filename to the application It is separated from the filename by a full stop extrapolation A process whereby values outside the limits of a field are extrapolated from values within the field See also isoparametric mapping face load A load type that converts a pressure over an element face in 2D or 3D into equivalent nodal loads See also uniformly distributed load fatigue When a material is subjected to repeated tensile stresses within the elastic range the material tires and fractures after a large but finite number of repetitions of stress This is termed fatigue See also damage log life feat
179. an optimum manner See also optimisation frontwidth The maximum number of unknowns at one time in the solution front is known as the frontwidth of the problem See also optimisation fully coupled A coupled analysis in which the structural and thermal files are run at the same time and communicate with each other via a data transfer file See also coupled analysis semi coupled fundamental mode The lowest dynamic natural frequency or buckling load factor of a structure It is often associated with the simplest mode shape gap A specified distance through which a structure must move before additional external forces come into play Modelled in LUSAS using joint elements Gauss point Position where numerical integration takes place within an element hence giving the greatest accuracy of results For more information see Gauss Point Quadrature Rules in the appendix of LUSAS Theory Manual 2 440 Index Gauss point results Results at the element Gauss point position See also Gauss point averaged nodal results unaveraged nodal results general loads See discrete point and patch loads generalised freedoms Degrees of freedom specified in a modal dynamic analysis which are used in the reduction of the global system of equations The accuracy of this method is determined by the selection of appropriate freedoms generalised stress See von Mises stress geometric nonlinearity Arises from significant changes in the struct
180. ance Controls the distance within which Point features must lie before they will be considered for merging Geometry tab Q Make New Features Unmergable Sets the merge status of all new features to Unmergable Geometry tab Q Merge Characteristics Controls the criteria that must be satisfied before features sharing a common definition will be merged Geometry tab See below Merge Characteristics Features will be merged only if they share common lower order features in addition feature merging is dependent upon attribute assignments By default identical assignments must be found on two features for those features to be merged The merge type parameter controls how LUSAS handles feature merging The following merge types are supported Q Off where no merging is carried out Q Exact where features are merged only if all assignments are identical This is the default LI Wild where features are merged if feature assignments of the same type for both features match The assignments of both features are retained where the assignment type is unique to one feature LI Ignore Assignments ignores the assignments when deciding if two objects should merge this is the opposite of Exact where the two objects must have the same assignments to merge The assignments of the feature merged out will be transferred to the feature retained unless the retained feature already has that particular assignment Notes e If several features are m
181. and shells e For plates and shells top middle and bottom stress and strain are available e When applicable Wood Armer results composite failure values design factors and beam stresses are available from the Stress results type e The results calculation and display may be controlled independently using the Result Plots dialog activated from the top level of the Groups context menu See Groups for details Results Transformation By default displacements loads reactions residuals velocities and accelerations are output relative to the global Cartesian axis For beams joints and shells stress and strain output is relative to element local axes For all other elements stress strain and creep plastic strain results are output relative to the global system Sometimes it is useful to transform the results to a consistent or alternative coordinate system For example if the elements in a model are orientated such that their local axes vary from one another the results may be transformed to a consistent direction 322 Chapter 8 Results can be transformed by editing the contour values or vector layer properties or when using the print results wizard Local and Global Results When specifying a results entity the results may be transformed relative to Q Local coordinate Transforms results relative to a specified local coordinate Only available if a local coordinate has been defined LI Local Transforms results according to
182. and valid is used Ifthe Solver licence that matches the Modeller licence is in use or is invalid or unavailable Solver will re order all suitable Solver licences and internally list them such that the least functional Solver licence that is still able to solve the job is listed first Once listed Solver will tumble through the licences in the list until one is found that is both valid and available This is then used for the duration of the analysis Creating shortcuts Shortcuts can be created to tie a licence type to a shortcut used to run LUSAS Solver For more information see the LUSAS Configuration Utility Post Analysis Checks All Analysis Types 1 Check the deformed mesh for each loadcase to ensure the model has deformed as expected 2 Compare your finite element results with estimates of stress and deflection from hand calculations This may not always be possible to do very accurately but an estimated should be obtainable 3 Check reactions for equilibrium 314 Chapter 7 4 Check magnitudes of displacements and stresses If possible compare to hand calculation 5 Check for matrix conditioning messages Small pivot and diagonal decay warning messages are invoked when the stiffness matrix is poorly conditioned Diagonal decay means that round off error during the solution has become significant which could lead to inaccurate results A poorly conditioned stiffness matrix is the result of a large variation in ma
183. arning is output is actually quite conservative controlled by a system variable DECAYL default 0 1E5 Although a check would always be recommended for any Warning of this description significant effects are not generally expected until the decay reaches a value of 0 1E8 or greater Poor conditioning of the stiffness matrix occurs because of large variations in the magnitude of diagonal stiffness terms and may be due to LI Large stiff elements being connected to small less stiff elements An example may be where a stiff beam element is being used to transfer load into the structure The stiffness of the beam would need to be reduced typically the beam would only need to be 1000 times the stiffness of the local elements LI Elements with highly disparate stiffnesses e g a beam element may have a bending stiffness that is orders of magnitude less than it s axial stiffness For instance the cantilever beam problem is notoriously problematic with respect to ill conditioning because of the potential for large differences between the axial and shear rotational stiffness components A typical stiffness matrix might be EA L 0 0 u K 0 126 02 6BI L v 2 3 0 of 1261 E 0 400 The longer the beam the greater the difference between EA L and l Appendix B 21 Potential data input mistakes leading to poor conditioning Poor conditioning may be as a result of deliberate modelling strategy but more usually an error in one
184. arts of a model can be connected so as to behave as if connected by rigid links These geometric constraints are only valid for small displacements Constraint equations can also be used to model cyclic symmetry for example a single blade from a complete rotor may be modelled and then constrained to behave as if it were part of the complete model As constraint equations refer to transformed nodal freedoms any local coordinate assigned to the features are taken into account during tabulation when the constraint equations are assembled Several different types of Constraint Equations can be defined from the Attributes gt Constraint Equation menu item Constraints are grouped under the following types Displacement Control LI Specified Variable a nodal freedom takes a specified value across all the nodes in the assigned features In this example a specified variable constraint of Displacement in the X direction with value 1 0 is assigned to Point 1 The underlying node is then allowed to displace only by the specified distance in the specified X direction Q Constant Variable used where a nodal freedom value is constant but unknown across all the nodes in the assigned features In this example a constant variable constraint of displacement in the X direction is assigned to Line 1 The underlying nodes move a constant amount in that direction 230 Chapter 6 LI Vector Path The nodes in the assigned features may be constrained to m
185. assigned to the model geometry so that the reserve strength can be visualised over the entire model Once assigned to the model the following stress components are available for display via selections made on the Contours properties dialog 0 Tsai Hill 0 Hoffman 0 Tsai Wu 0 Hashin Fibre 334 Chapter 8 Q Hashin Matrix Results may be printed or displayed using standard results processing facilities Note that a failure criteria greater than 1 indicates failure See the Theory Manual for further information Composite Failure Contours When using the Hashin failure material model the failure indicator IFFLR can be contoured The indicator has the following values Indicator IFFLR Description 0 1 No failure 1 2 Matrix failure 2 3 Fibre failure 3 Matrix and fibre failure Results may be printed or displayed using standard results processing facilities Interactive Modal Dynamics The Interactive Modal Dynamics IMD facility within Modeller calculates the modal response of a system to a given input using the eigen modes and eigenvectors from an eigen analysis Note that the eigen analysis must have been performed with mass normalised eigen modes An IMDPlus software option extends this capability to solve 2D and 3D seismic and moving load analyses using modal superposition techniques in the time domain For details see the JIMDPlus User Manual Interactive Modal Dynamics calculations within Modeller may be performed on single
186. ast record of a file has been read engineering strain A strain measure which has its reference as the current length as opposed to the undeformed length enhanced strain A strain field used to modify standard continuum elements to improve accuracy in which the internal degrees of freedom are eliminated at the element level before assembly of the stiffness matrix for the structure enthalpy A physical property of a material which governs how much heat is liberated or absorbed during a phase change envelope Defines the maximum and minimum variation of results across specified load cases combinations or other envelopes environmental node A means of distributing heat which is transferred to the medium separating a number of thermal surfaces environmental temperature A load type which describes the temperature of the medium surrounding a body equilibrium A state where applied external loads on a model are balanced by the generated internal forces equivalencing Nodes existing at a similar point in space may be replaced by a single node equivalent stress See von Mises stress error message A visual indication of hardware or software malfunction or of an illegal data entry attempt or command sequence 436 Index Eulerian geometric nonlinearity A strain formulation which has its reference as the current configuration See also updated Lagrangian total Lagrangian excitation The forcing of a structure by
187. astic torsion Warping function more common quasi harmonic Place torsion Stress function applications and the associated Elecite conduction Electric potential field variable are listed in the Electrostatics Electric potential table shown right Magnetostatics Magnetic potential Two types of field analysis may be performed LI Steady State field analysis Q Transient field analysis Facilities for thermo mechanically coupled analysis are also available The solution of this class of problem follows an identical process to that of the structural problem The domain is discretised using a series of field elements thermal material properties are specified thermal loads are applied and the equations solved for the values of the field variable at each nodal point Thermal link elements or the specification of thermal surfaces determine how heat is conducted convected or radiated across gaps and 304 Chapter 7 spaces between different domains Since the most common application is that of thermal conductivity subsequent discussion will be directed towards this type of analysis Steady State Thermal Analysis In a manner similar to static structural analysis steady state field analysis assumes that the loaded body instantaneously develops an internal field variable distribution so as to equilibrate the applied loads It should be noted that the use of temperature dependent material properties or loads renders the problem nonlinear Transient
188. ate Fick lt 0 1 1 lt fck S0200 ma Proportion of design strength ret EN1992 1 1 3 1 7 Siran Thick Plate amdan beta to centre of compression block Asitirw d rhol Reintorceamert density 16 a7 18 19 20 21 22 23 Strain Thick Plate 26 25 2 27 28 23 39 Strain Thick Piste fyk rhoLtete icdemde gammaS xoverd compression Zone G a proportion of d Strain Thick Piste Fiick lt 50 0 0035 0 0026 0 0357 S0 1ck 100 4 epsioncus Peak strain in concrete ref 6N1992 1 1 Table 3 1 Strain Thick Plate TA tye 1000 Es epatanCU3 1 yieiaratio Yisking ratio Force Moment Thick Piate F xoverd lt yiekrato t 0 Vieldcheck Check if retorcemert has yiekied 10K Strain Thick Piste xoverd d xe Compression zone depth nm Strain Thick Plate c bete xe za Lever am men ForceMoment Thick Piste As tyk zatgammeas 1 000000 MRG Ulimasie moment capacty kNm i Forcemomernt Thick Piste MR Usage Usage factor gt ESS cma Hp Using named expressions After definition the user results components created can be selected by name from the Component drop down list on the Contours Values and Diagrams layers properties dialogs All standard LUSAS results processing viewing animating graphing printing and report capabilities can be used with any user defined results components 5 Els IQ IF 18 9 deck _use_check md Sy deck_user_check md Window 1 Altrtudes Mesh Utitties E Contours Usage
189. attribute image shows an attribute has been assigned to the model or used in the definition of another attribute A greyed out attribute image shows an attribute has yet to be assigned to the model or used in the definition of another attribute E A coloured or greyed out attribute with a surrounding red box indicates an attribute that has been set as default meaning it will automatically be assigned to features of the model as they are generated 116 Chapter 6 Se LUSAS Modeller spannar md Fie Edt View Geomety Alidbutes Unite Window Help De u e s px orre Bf mr a is ae a kB Bere aig amp jele im ES oo TER i r U L E e apima mi E Magii _ Toolbar buttons UR ed Aihe Irii il 4 Diviionped il anhics Wing EDinidonel __ SET Graphics Window 6 Divisione ll Timona E n e ra kb adrape 1 T y Lamama Recut Tile 1 au r Esti men Sy Suis 3 Sy LU The here amp 2 Thickrwee 15 fy BThichressxt0 ppl Sy Musei TUSAS D T E ERE SHE oie l desi IF d TH Stee Ungraded Hre H sia Graphics Window Sy Supports 11 i diir Firme Ha 2 Fully Fired 2 shied apy e anon Text Window H MEER ey ees N Max at wt Hoda 177 Compenank GE m Hi RITI E obtbede HF z Status Bar gt e file l alts sseeabl d sorosa different gecmeiric property assignments dene bel reaulta de I Sd ose r
190. attribute name in the Treeview and clicking the right mouse button to choose Select Assignments or Visualise Assignments from the context menu This is the easiest way to interrogate the assignment of a single attribute Contour layer materials geometry loading attributes only Allows the model to be contoured with a specified value obtained from the material geometric or loading attribute assignments This is especially useful when an attribute value changes across the model e g when defined using a variation To use with nothing selected click the right mouse button in the graphics area Choose Contours from the context menu Select either Loading model Geometry model or Materials model Colour by attribute Accessed from the properties dialog of the Geometry layer colours the geometry according to which attributes are assigned to which features A key is generated to identify the colours The options Combine assignments using loadcase history and Show only assignments in the active loadcase Accessed from the properties dialog of the Attribute layer for supports activate attributes only allows load dependent attributes 118 Chapter 6 to be visualised from the accumulated load history or from only those attributes assigned to the active loadcase In addition to the above toolbar buttons for Supports and Loading Ea can be used to turn on and turn off the display of any supports or loadings that are assigned to a pa
191. atures and stress concentration using None Surface and Line mesh attributes By default the maximum angle around an arc subtended by a single element is 90 degrees This may be adjusted on the Meshing tab of the Model Properties dialog Notes e A good initial mesh is usually obtained by specifying the element size as approximately 1 50th of the diagonal model size Specifying too small an element size will cause too many elements to be generated and may result in LUSAS using up all the available memory Specifying too large an element size will cause the meshing algorithm to fail e The success of tetrahedral meshing is dependent on the quality of the Surface mesh If the meshing algorithm fails invoke edge collapsing or set the Volume mesh to From defining geometry and adjust the element size using Line and Surfaces mesh attributes of type None If the meshing still fails try breaking the Volume into a number of smaller Volumes 127 Modeller Reference Manual Edge Collapsing The quality of the mesh may be improved using edge collapsing Edge collapsing removes elements with very short sides or acute angles by merging them with neighbouring elements This is particularly useful when generating tetrahedral elements on imported CAD models where very short lines are present Edge collapsing is invoked from the Advanced button on the Meshing tab of the Model Properties dialog Mesh before edge collapsing Mesh after edge collapsin
192. axes of Lines and Surfaces to be consistent this can be achieved by reversing and cycling the features Consistent axes for underlying Lines Surfaces and Volumes ensure that their elements also have consistent axes 1 Draw the orientation axes for the features which are required to be consistent Geometry Layer Properties It may be useful to draw just Surface normals 2 Inthe case of lines reverse any lines whose orientation is to be changed 3 Inthe case of Surfaces reverse Surface normals local z axis and cycle Surfaces xy axes until all axes are consistent Surfaces can be cycled relative to a reference Surface if required 4 Inthe case of Volumes set up the Volume local z axis and cycle xy axes by cycling the first Surface in the Volume definition until all axes are consistent Volumes can be cycled relative to a reference Volume CAD Interfacing CAD interfacing is the process of importing or exporting the geometry and other data from and to a CAD package When importing from CAD only the relevant data should be exchanged Annotation and construction lines should not be included as these will then be converted into LUSAS geometry Control over the data imported into LUSAS is achieved using the Advanced button accessed from the File gt Import Geometry menu item Similarly control over what is exported is achieved by options on the Export dialog accessed from the File gt Export menu item For more information see Interface F
193. ay be that the value used is not sufficient The solution is typically not overly sensitive to changes in this parameter and therefore any changes tried may be in terms of orders of magnitude Negative Eigenvalues Are Calculated LI Check for Warnings or Errors Check the output file for any other warnings or errors There may be diagonal decay or pivot warnings that will indicate node and element numbers and help to identify any suspect areas of the mesh Q Iteration Vectors Increase the number of starting iteration vectors If any of the modes are close together the default magnitude for this parameter may not be sufficient to allow accurate resolution in their extraction Increasing this parameter is also essential if only requesting a small number of eigenvalues 1 2 Ten iteration vectors would be a reasonable starting value for such a situation LI Convergence Achieved Ensure that the solution converged correctly If not then increase the number of iterations permitted LI Convergence Tolerance Tighten the convergence tolerance since some modes may be close together and require greater numerical resolution This may also require an increase in the number of iterations permitted LI Reduce Load Level Reduce the load applied to ensure that it is below the lowest expected buckling mode of the structure A negative eigenvalue in a buckling analysis could also simply mean that the applied loading is in the opposite direction to that which
194. ay note that a single null line mesh should be used having one mesh division For the invalid region shown a dummy Line can be added manually between the 2 overhanging points to close the bay and make the search area valid When closing the bay in this way note that a single null line element having one mesh division should be assigned If done the resulting cell of five edges will be subdivided into 4 triangles There is no limit to the number of edges that may hang over the main body if the overhanging members are only separated by one edge right In these cases LUSAS automatically closes the cell and either sub divides the resulting cells into triangles or uses a quadrilateral as appropriate 211 Chapter 6 Invalid 2 edges overhanging from same node Made valid by connecting points with a null line mesh Invalid overhanging edges separated connecting overhanging points with a null line mes Valid Search Areas Modeller Reference Manual Processing Loads Outside a Search Area For point and patch loads any load outside a search area can either be excluded from the search area or be projected to be included into the search area Discrete loads on lines When discrete loads of patch or point loading are assigned onto Lines with an assigned Search Area the individual load components are projected onto the line normal to the local x axis of the Line and their effective loading is calculated and a
195. be made invisible using any of the following methods U By selecting features and choosing Invisible from the context menu activated from the graphics window Q By selecting an attribute from the ob Treeview and choosing Invisible from its context menu UL By creating a group from selected model features and choosing Invisible from the group name s context menu to make the members of the group invisible Features may be made visible by using any of the following methods Q By choosing All Visible from the context menu activated from the graphics window used if any features have been made invisible LI By choosing Visible from an attribute s context menu to re display the features assigned to the attribute Q By choosing Visible from a group name s context menu to make the members of the group visible again In addition the advanced visibility dialog activated from the graphics window context menu allows fine control on the visible invisible items by controlling the visibility of higher order and lower order features 1 e This allows all Lines attached to a Point to made visible or all Surfaces connected to a Line to be made invisible Notes e All visible features will always have their lower order features visible 1 e If a line is visible its defining points will also be visible e When a feature is made visible any associated elements or nodes will also be made visible Use the Advanced Visibility dialog to override this behaviou
196. be the lowest in the range unless the Fast Lanczos solver is used A number of shift points are set up from which the eigensolutions are computed These are determined by the maximum number of eigensolutions system parameter MEIGSH that can be located from each shift point Shift points may be altered automatically in order to improve the rate of convergence Eigensolutions are computed from each shift point in turn until all eigensolutions have been located Note By including Modal Damping the overall damping factors at the eigenmodes can also be output as a table in the LUSAS Solver output file These values may then be used in a Dynamic analysis if desired Modal damping is only applicable to a Frequency analysis Inverse Iteration With Shifts Eigenvalue extraction by inverse iteration may be utilised when calculating an eigenvalue range or frequency range 295 Modeller Reference Manual This method uses a series of shift points from which to extract the eigensolutions using the inverse iteration method The convergence to each eigensolution is governed by the closeness of the eigenvalue to the shift point and the method is thus efficient for locating the eigensolutions within narrow bands Convergence Of Inverse Iteration As the procedure iterates it is necessary to refer the numerical solution to a criterion with which to measure its convergence For inverse iteration it is important that the eigenvectors as well as the eigenval
197. ble precision n nnnnnnnnnnnnnE ee Currently LMSPRC can take the following values LMSPRC 1 Single precision format default LMSPRC 2 Double precision format LMSPRC 3 Double precision format on a single precision machine LMS Export LI Option 290 must be set before tabulating a model to ensure element matrices are transferred from LUSAS LI Option 290 allows you to instruct LUSAS to output the element STIFFNESS and MASS matrices to the mys plot file The volume of data transferred can be substantial so this option is turned off by default LI Nodal Freedoms LMS supports only six degrees of freedom X Y Z Rx Ry and Rz If unsupported freedoms are encountered a warning message is issued If this section 64 Chapter 3 is not present it will not affect the translation of the neutral file into LMS as long as no node statement contains a reference to a Frnnn freedom label LI Node Coordinates The node co ordinates are written with the co ordinate system omitted implying the use of the global co ordinate system The Modeller node labelling scheme is preserved during the export process Q Material Properties mdl file Isotropic 2D Anisotropic and 2D Orthotropic materials are supported 3D material properties are exported as ANISO3D however the values are read but not used by LMS Joint properties are output in the element property section of the neutral file Q Material Properties mys file Material properties are tran
198. c material orientation is specified as global relative to a local coordinate system or relative to the feature local axis system Optional thermal expansion and dynamic constants can be specified Note that not all elements accept all the orthotropic models Refer to the Element Reference Manual for full details of valid element material combinations Orthotropic models are Plane stress Plane strain Thick Axisymmetric Solid L Thermal is used to specify properties for general thermal and heat of hydration analysis For general thermal analysis phase change state thermal conductivity specific heat coefficient and enthalpy values can be set For concrete heat of hydration analysis where internal heat is generated by the chemical reaction between cement and water as concrete hardens additional thermal options such as exotherm type cement type and timescale units can be specified Q Plastic Used to model ductile yielding of nonlinear elasto plastic materials such as metals concrete soils rocks sand LI Hardening Used to model a nonlinear hardening curve data Hardening is defined as part of the plastic properties Isotropic Kinematic and Granular sub types are available Isotropic hardening can be input in three ways 164 Chapter 6 LI Creep Used to model the inelastic behaviour that occurs when the relationship between stress and strain is time dependent LI Damage Used to model the initiation and growth of cavities and micro cracks
199. c or nonlinear material properties with options for plasticity hardening creep damage continuum or composite viscosity and two phase materials Q Anisotropic Different material properties are specified in arbitrary non orthotropic directions by direct specification of the modulus matrix LI Rigidities Allows direct specification of the material rigidity matrix In plane and bending rigidities are defined from prior explicit integration through the element thickness Q Thermal Applicable to thermal field elements only Whenever thermal elements have been used in a model thermal material properties should be defined and assigned to the relevant parts of the model Q Joint Linear and nonlinear joint material models for contact and impact analyses using joint elements 162 Chapter 6 Specialised Material Properties Q Rubber Defines materials with hyper elastic or rubber like mechanical behaviour Q Crushing A volumetric crushing model such as would be used for crushable foam filled composite structures LI Generic PolymerDefines a material model consisting of a number of parallel Maxwell units an Eyring dashpot and a non linear spring which can incorporate damage to represent the behaviour of polymer like materials L CEB FIP 1990 Concrete Shrinkage and Creep Defines a material to predict the mean behaviour of a concrete section due to creep effects Q Elasto Plastic Interface Defines a material to represent the friction
200. cal Axis dialog unless any model viewing shortcuts are being used at the same time A benefit of this approach is that no matter where on the screen you click to start the rotation of your model if you return the mouse pointer to the same spot whilst you are dynamically rotating the model the model will return to its original position and orientation on the screen Vertical axis LI Incremental rotate Allows the model to be rotated by bly an specified rotation about a chosen global axis The specified rotation may be modified by adjusting the chy anti clockwise Y rotation increment on the window s properties eb Clockwise Y Anti clockwise Clockwise Gt Anti clockwise 2 Gl Clockwise 2 Q View along axis Views the model along a chosen global F axis Note that this toolbar button is not provided as part of the A Show XY 42 standard user interface but it can be added by selecting the View Show xY Z gt Toolbars gt Customise gt menu item oh Show ZY X Note that this facility is also available by clicking in the X Y or J Show ZY CX Z boxes in the Status Bar holding down the Shift key if ws Show sz i needed to obtain the views along the negative screen axes A Show 2 i G8 Show Isometric dA Show Dimetric Ei Show Trimetric Zooming in or out h d Zoom tool This tool works in two ways 1 By dragging a box around part of the model the view will zoom into that area
201. cal coordinate systems for use with this command For 3D elements care must be taken to ensure the transformation is valid by limiting the shell plate elements showing results to those parallel to the global XY plane Modeller Reference Manual Notes e When viewing Wood Armer results this facility is used to set the direction of the X reinforcement A skew angle may then be set independently to define the Y reinforcement direction The default skew angle is 90 degrees e When viewing shell moments and shear stresses using a cylindrical or spherical local coordinate the shell plane for resultants may be defined as rt tz or rz where r is the radial direction tis the theta direction and z is the cylindrical axis Combinations and Envelopes Combinations and envelopes can be defined for manipulating results loadcases Q Combinations enable results from different loadcases to be added together For example 9 Ole the results from a self weight loadcase and a m a Losdcases concentrated load oadcase might be added 5 ra Structural or perhaps the results from a dead load HN 1 Dead Load loadcase and an IMD loadcase used for 1 2 Superimposed Dead Load E a SHA upper spectral analysis might be added HT 4 HA lower f i SKEL upper 0 Combinations can be created from loadcases i BEL lower or other combinations or envelopes Bea 7HB lower e e oh P HA KEL both lanes E Envelopes are used to pick out the maximum
202. cations along a model and using the arbitrary section property calculator in Modeller to calculate and save the properties to a library prior to using this dialog Where both ends of a beam have been defined using either a LUSAS supplied standard library item or one of the LUSAS standard section calculators an exact calculation can be made to arrive at intermediate section properties based upon the known shapes at either end of the beam In cases where one or both ends of a beam section have been defined using the arbitrary section calculator and this includes section properties calculated from the precast section range a choice of interpolation method is provided When the tapering option is chosen the vertical and horizontal alignment of one end of the beam section from the other can be specified Tapered beams would normally use the same section shape at either end but differing sections can be accommodated Offsets eccentricities of beam ends from nodal positions can also be defined When modelling varying cross sections with constant section beam elements care should be taken to ensure that sufficient elements have been assigned See Notes for details Q Cross section information is used to define a series of quadrilateral shapes that define the true cross sectional shape gt of the bar grillage beam element It generally only needs to be defined if a beam s properties have been defined manually and it is required that the beam s shap
203. cations by clicking the right mouse button and selecting Copy from the context menu Saving pictures for viewing in Expose Pictures can also be saved as LUSAS Picture Files for viewing only in the LUSAS picture file utility program Expose Note that Graphs cannot be saved in LUSAS picture file format The contents of the graphics area can also be transferred to the Windows clipboard using the copy button Generating Reports Report templates which are created modified and saved Lf in the E Reports Treeview for each model hold the B Repot Reports 1 Report 1 information required to generate reports of your model or E Points results data Each time a report is to be viewed the report ah es details that are specified in the report template are E Geometric extracted from your model and results files and used to Asie create the report E Local Coordinate rae H Loadcases You build a report by defining chapters that reference the Chapter 1 Displ t model and results data that you want to include in the Bd Ecece Memeri Thick 30 Beem report The modelling and results data you select can be E 3D_frame_analysis bmp restricted to particular model geometry model attributes or loadcases or for particular results entities and data can be listed for all of or just parts of your model Additional user content such as screen captures saved images or additional text can also be added These
204. ch no material damage is assumed to occur when using the nonlinear damage material model It is the linear elastic limit point damping Any mechanism that dissipates energy See also mechanism data check A LUSAS analysis which progresses as far as the pre solution stage The data file is checked for errors and a plot file is created for visual checking in the post processor Frontal optimisation is carried out if the default solution order commands are included data file The LUSAS database must be formatted before solution The formatted analysis file is known as the data file data transfer file A file used to store information during a coupled analysis for access by the secondary analysis See also coupled analysis default An action or value that a computer or program automatically assumes unless a different value or instruction is given define To create a dataset Datasets are used to store information about features attributes utilities and results See also edit feature attribute deformation gradient A tensor used in continuum mechanics for defining certain strain measures 431 Modeller Reference Manual deformed mesh The mesh displayed in a deformed state when subject to an external load or when a mode shape is being displayed See also undeformed mesh degrees of freedom Express the manner in which the nodes are free to displace delamination The separation of bonded plys in a laminated compo
205. combined uniaxial A description of a material model in which one axis is considered to determine the material response See also biaxial triaxial uniformly distributed load A load type which specifies a load per unit length along a line element or a load per unit area for a surface element units A system of dimensions in which the model and associated properties and loads are defined See also SI units unzoom The action of reverting to an unmagnified view of the structural model See also zoom updated Lagrangian A strain formulation which has its reference as the end of the last converged increment See a so Eulerian geometric nonlinearity total Lagrangian upgrade To expand a system by installing options or using revised or updated software utility dataset A utility dataset stores items in the database that are not assigned directly to features See also transformation dataset control dataset variable A quantity that can assume any set of values as a result of processing data 468 Index variation A dataset used to vary an attribute over a feature A variation dataset can be described in terms of field variables interpolation values and functions vector plotting Results with both a magnitude and direction may be represented by a vector whose length is proportional to the magnitude See a so displacement vectors principal stress vectors velocity First derivative of displacement with respect to tim
206. component results in tabular format 371 Modeller Reference Manual Q Summary maximum and minimum visible values and their position on the model LI System forces forces in global or current transformed directions LI Gap forces forces required to reverse nodal penetration LI Contact forces forces generated across contact surfaces LI Contact stresses contact stresses computed as contact force contact area in normal and tangential directions LI Section results generic contact results e g contact state normal penetration etc For more details see slideline results processing Thermal surfaces results LJ Component underlying nodal results Q Summary maximum and minimum values according to the extent specified and their position on the model LI Flows flow components Q View factors summary of view factor sums across segments Transformation of results Printed results may be transformed to be relative to a specified local coordinate according to element local directions for stresses relative to the local element material directions or to a specified angle in the XY plane Location When applicable printed results can be obtained for the following locations L Averaged nodal Average nodal smoothed results from visible elements Nodal results are extrapolated from the Gauss point values within each element before averaging Q Gauss Point Gauss point values internal to the visible elements
207. contact relationship within planes of weakness between two discrete bodies LI Delaminationmodels for use with the composite delamination interface elements Q Mass material models for specifying mass in structure using non structural mass elements LJ Nonlinear User A user defined constitutive model defining the stress from strain LJ Resultant User A user defined constitutive model defining the stress resultants from strain Editing of Material Properties Editing of pre defined material data such as that provided in the material library allows users to view both the original material definition input data as well as modify the values used Editing of user defined material properties only permits viewing and editing of the values used Material properties added to the Attributes Treeview have context menu entries named Edit Definition and Edit Attribute e Selecting the Edit Definition menu entry or double clicking the attribute displays the original definition dialog with all the original input data intact e Selecting the Edit Attribute menu entry displays values that can be modified For materials added from the material library these values may be changed but this breaks the link to the original definition dialog and a warning message will be displayed Notes e Material property attributes can be formed into a composite lay up using the composite attribute facility e Once assigned to geometry material directions can be
208. content can be saved in BMP JPG or WMF file formats Tip All file types assume the default extensions that are given in brackets When specifying filenames it is good practice to simply supply the filename without the file extension LUSAS will then supply the correct extension for the file type being written which will ensure that existing files are not inadvertently overwritten by specification of the wrong file type Model Files Model files contain all the information regarding the current database and settings The information is stored in an binary form and may only be accessed using LUSAS Modeller A model file is not saved automatically LUSAS Modeller prompts on exit as a reminder to save changes to a model file LI New accessed from the File gt New menu item prompts to close an existing model file and creates a new model file Q Save or Save As accessed from the File menu saves the current model to disk at any time Save As allows specification of an alternative filename LI Open Previously saved model files may be opened by choosing the required model file using the File Open dialog Modeller will prompt for confirmation before the currently loaded model is closed LI Close Closes the currently open file Notes e When using version 14 of Modeller old version 13 models may be read but this may take longer than usual as the files are converted e When saving a model disk space may be saved by deleting the mesh and faceti
209. ct stress must be given a value which physically represents the model to be analysed User Supplied Creep Properties The user creep facility allows user supplied creep laws to be used This facility provides completely general access to the LUSAS Solver property data input and provides controlled access to the pre and post solution constitutive processing and nonlinear state variable output 176 Damage Chapter 6 Notes e The user supplied routine must return the increment in creep strain Further if implicit integration is to be used then the variation of the creep strain increment with respect to the equivalent stress and also with respect to the creep strain increment must be defined e Ifthe function involves time dependent state variables they must be integrated in the user supplied routine e If both plasticity and creep are defined for a material the creep strains will be processed during the plastic strain update Stresses in the user routine may therefore exceed the yield stress e User supplied creep laws may be used as part of a composite element material assembly See the Solver Reference Manual and the Theory Manual for further details Damage is assumed to occur in a material by the initiation and growth of cavities and micro cracks The damage models allow parameters to be defined which control the initiation of damage and post damage behaviour Damage models are available for continuum and composite element
210. cting the Individual offsets menu item from either the Vertical or Horizontal Alignment drop down menu then accessing a section s properties by clicking the launch dialog button I in this cell and entering an offset value on the Enter section dialog When individual offsets are specified on a follower section any connection with the master section is broken and any offsets specified on a master section will no longer update the offsets on a follower section Interpolation of section properties Where all sections have been defined using either a LUSAS supplied standard library item or one of the LUSAS standard section generators an exact calculation is made to arrive at intermediate section properties based upon the defined shape see Shape Interpolation above between the sections If the shape of the cross section cannot be interpolated because one of the sections has been defined using the arbitrary section calculator or if sections are of completely different shapes the engineering properties at locations along the multiple varying section can be calculated in two different ways Q Enhanced interpolation uses proprietary LUSAS equations to calculate best estimate cross section properties for locations along a beam from the cross sectional area A and Moment of Inertia 1 values of the sections defined at each beam end See the Theory Manual for more details Q Linear interpolation calculates cross section properties for l
211. ction may be applied using one of formula provided The maximum displacements forces and stresses are computed throughout the structure for each eigenmode These values may then combined to produce a single positive result using a spectral combinations The spectral combinations available are CQC default SRSS and Absolute Sum For further details see the LUSAS Theory Manual L Power Spectral Density PSD Analyses the frequency response to a random modal vibration such as aerodynamic loads acting on an aircraft component A frequency PSD defines the frequency content of the random loading Dynamic excitation should be applied to all the supports via support motion excitation Frequency and Time Domain Response Frequency and time domain response calculations are the most commonly used Usually a node is excited across a frequency or time range to generate a graph for the frequency or time response using the Utilities gt Graph Wizard menu item From the response across a range a single frequency may be selected to perform an IMD calculation on the whole structure using an IMD loadcase The following diagrams illustrate this procedure Results across a frequency range or time history Response at a node calculated across a specified Response at a node calculated across a specified frequency range time history jo stress 20m displacement BO 50 0 30 20 in frequency OO 00 00 00 OF 050 00m 070 0A 0 1m 339 Modelle
212. d accelerations in an analysis However initial values may be defined without using load curves if no other load type is controlled by a load curve e If velocities and accelerations are prescribed for the same variable at the same point in time in an analysis the acceleration will overwrite the velocity and a warning will be output An exception to this rule occurs for implicit dynamic analyses where an initial velocity and acceleration may be used to define an initial condition for the same variable e If initial conditions are to be applied refer to Transient Dynamic Analysis for details on how to compute the data input required for the appropriate integration scheme Discrete Loads Discrete loads are defined in relation to their own local coordinate system the origin of which is given by the coordinates of the Point feature to which the load is assigned Note that discrete loads are always assigned to Points Discrete loads differ from feature based loads in that they are not limited to application over whole features and may be effective over full or partial areas of the model Discrete loads may be projected over an area onto Lines or into Volumes Examples of discrete loads that are created automatically by LUSAS include those created for vehicle and lane loading and equivalent nodal loading defined as a result of using a Prestress Wizard Separate discrete loads may be applied to a model as a set or load train using the Compound load
213. d be made available when calling the support desk This information will help the support engineers get to the bottom of your problem more quickly e The exact text of any warning or error message s e Machine specification operating system memory and available disk space e A copy of the model or data file causing problems e A list of the last commands used in LUSAS Modeller or a copy of the session file e The contents of the last LUSAS Modeller error log LUSASM_x ERR e Full details of the LUSAS Modeller LUSAS Solver version numbers in use the LUSAS Solver version number is written to the header section of the output file and the LUSAS Modeller version number is obtained from the Help gt About LUSAS Modeller menu item e For complex or difficult to describe problems email or fax a simple diagrammatic representation before calling to aid any discussion Try to be logged onto the machine when calling or be close enough to the machine to try a suggestion provided by the support engineer For an explanation of the errors which may occur during the Solution see Appendix B LUSAS Solver Trouble Shooting Sending files to LUSAS Technical Support Use the LUSAS Support Tool to create a compressed file of all relevant data to send to LUSAS Techincal Support 312 Chapter 7 Pre Analysis Checks 09 So ee E 10 11 Notes Check the consistency of your co ordinate systems between the finite element model and any engin
214. d on classical continuum mechanics principles The output from these elements is in terms of continuum stresses rather than stress resultants contour plot A graphical representation of a results pattern across the surface of the model See also colour fill 428 Index control dataset A dataset containing LUSAS analysis control information The parameters stored in these datasets control the progress of the analysis A control dataset is assigned to a load ID See also assign convection The process of transmission of heat through liquids or gases at a body surface by means of the motion of the fluid See a so conduction radiation convergence When using incremental iterative solution algorithms a measure of the convergence of the solution is required to define whether equilibrium has been achieved See a so increment Iteration displacement norm residual norm work norm coprocessor A microprocessor device connected to the central processor that performs specialised floating point computations more efficiently than the CPU alone See also central processor coupled analysis The interaction between a thermal and structural analysis may be studied by performing a coupled analysis Also known as thermo mechanical coupling See a so fully coupled semi coupled copy To create a new feature by copying an existing one using a transformation dataset See also move transformation dataset CPU time A measure of actual processin
215. d to a draping surface This is done by selecting and placing the Surfaces defining the drape surface into selection memory and assigning the composite attribute to the model For the FiberSIM Solids and Shells and Simulayt Solids and Shells definition methods e No assignment to a draping surface is required because the layup data is already included and correctly positioned in the FibreSim or Simulayt XML files However the composite attribute must be assigned to the model to enable visualisation of other composite model data If a model has been meshed prior to the assignment of composite properties Visualisation of Composites Properties To visualise assigned composites properties the surface or volume must be meshed The following composite properties can be visualised Fibre ply directions Draping grid Lamina thickness Skew angle Offset layer Fibre volume fraction Visualisation of Fibre Ply Directions Once assigned to features which have a mesh assigned the fibre directions of assigned composite data can be examined graphically as follows Right click on the Attributes entry in the LE Treeview and select Properties On the Composite tab click on Settings and select Visualise ply directions The x and y axes define the warp and weft directions respectively the item x amp y displays both directions at the same time NO e Lamina directions can be plotted as an x y z or x amp y axes at any layer For solids the
216. d to the solid Note It is advisable to make a connection such as this reasonably distant from the main area of interest as it may affect the quality of the results locally 135 Modeller Reference Manual Fixing Mesh Problems When meshing any features which failed to mesh are noted in the text window These can be identified using the Identify Object dialog invoked by double clicking on the error message in the text window Alternatively a group can be created containing all the features that failed to mesh Only features that are not part of meshed higher order features will be added to the group To activate this facility choose the check box Create a group of features that failed to mesh invoked from the Advanced button on the Meshing tab of the Model Properties dialog When importing CAD models meshing errors can sometimes occur due to very short lines and small surface slivers in the model These problems can be alleviated in the meshing process by using edge collapsing When meshing open hollow volumes with tetrahedral elements the edges with nodes which have failed to merge are displayed automatically Unmerged nodes on volumes which failed to mesh Mesh with nodes merged by adjusting node merge tolerance Notes e Unmerged nodes are most easily seen when meshed using solid fill e Nodes which have failed to merge may be forced to merge by adjusting the node merge tolerance on the volume properties dialog or by assigning a
217. d up away from zero to the nearest integer ceil a a rounded down towards zero to the nearest integer floor a absolute value of a abs a maximum value of a and b max a b minimum value of a and b min a b x to power y pow x y remainder of a b mod a b Cylindrical and spherical field variation expressions can use radians default or degrees to specify angles If trigonometric functions are used in a field expression they will dictate what angular measure is used For example a function will use degrees if degree based trigonometric functions such as sind cosd and tand are used Notes e An expression may not mix radian and degree functions e Any angle cut off values will use the same units as the expression Maximum and Minimum Cut Off Values Maximum and minimum cut off values may be of global Z coordinate specified for the chosen coordinate system This allows M mun2 Ni the range of application of load to be limited such as would be necessary to model a structure not wholly saa submerged in water These examples right show field cut se variations in terms of the global X ordinate displayed i along a Line parallel to the global X axis The typical field expressions used are shown in the boxes next to cut offs in global Z each diagram All expressions are subject to a cut off in minimum and maximum X at parametric distances of 0 25 and 0 75 respectively This example shows a variation in terms of the global Z axi
218. dcase to a slice output window Q All prints slice results for all loadcases to a text file named SliceResultantsBeamsShells prn in the current working directory Q Selected prints slice results for entered loadcases to a text file named SliceResultantsBeamsShells prn in the current working directory As an example entering 1 5 7 would select loadcases 1 to 7 excluding loadcase 6 Notes e The assumption that plane sections remain plane which is required for the calculation e Linear variation of stress is assumed for the approach and therefore low order flat shells are supported 3 or 4 noded thin and thick shells and high order flat shells are calculated ignoring the mid side nodes if they are coplanar with collinear edges For curved high order shells the element is subdivided into constituent pseudo elements and each pseudo element interrogated using linear interpolation e The slicing path must be defined using straight lines arcs or combined lines containing only these two line types Splines and annotation lines cannot be used e Slice forces can only be computed relative to the intersection of the slicing path with the slice plane or the neutral axis based on the sliced section No facilities are available for the transformation of slices without defining a separate path and recalculating the slices e Taking slices at the free end of a structure can lead to overestimation of the forces and moments on the section This occurs due
219. de delamination is specified e Although the solution is largely independent of the mesh discretisation to avoid convergence difficulties it is recommended that a least two elements are placed in the process zone 143 Modeller Reference Manual Element Selection About LUSAS Elements Elements are classified into groups according to their function The element groups are listed below e See also Joint Element Meshes and Interface Elements for composite delamination e For full details of all elements refer to the Element Reference Manual e For full details of the element formulations refer to the LUSAS Theory Manual Point Element Selection Non structural mass and Joint elements are defined at or between points Generic Element Types 2D 3D Non structural mass PM2 PM3 Joint no rotational stiffness JNTS JNT4 Joint for beams JPH3 JSH4 Joint for grillages JF3 Joint for axisymmetric solids JAX3 Joint for axisymmetric shells JXS3 144 Chapter 6 Line Element Selection The following table lists the elements available for Line meshing by type and by name The first column matches the option list in the Line mesh dialog box Generic 2D 2D 3D 3D Element Types 2noded 3noded 2 noded 3 noded None Bar BAR2 BAR3 BRS2 BRS3 Thin beam BM3 BS4 Thick beam BEAM BMS3BTS3 Thick beam nonlinear Engineering grillage Cross section beam GRIL Semiloof beam BMX3 BSX4 Axisymmetric me
220. degrees measured from the positive z direction of the local xz plane clockwise about the local y axis when looking in the positive y direction y is the distance along the y axis e Fora local cylindrical coordinate defined along the x axis a point is specified as x r theta where r is the radius perpendicular to the local x axis theta is the angle in degrees measured from the positive y direction of the local yz plane clockwise about the local x axis when looking in the positive x direction x is the distance along the x axis L Spherical Based on the axes of a sphere defined by a radius tangential angle and angle around a meridian Coordinates of a point are specified as r t c where r is the radius of the sphere on which the point lies from the local origin t is the angle in degrees measured from the positive x direction of the local xz plane clockwise about the local z axis when looking in the positive z direction c is the angle in degrees measured from the positive z axis to the radius line Warning There is no equivalent spherical set in Solver therefore freedoms cannot be transformed using this type of local coordinate system 250 Chapter 6 e Surface local coordinate systems define a local axes which has the x and y axes in the plane of the surface and a local z axis normal to the surface This is useful for extruding a volume normal to a surface and assigning supports normal to a surface
221. dicate successive polygon vertices When at least three vertices have been indicated right click and select Cancel or Close from the context menu LJ Bitmap Adds a bitmap from a selected file LJ Banner Adds the LUSAS banner LJ Arrow Defines an annotation arrow of a default size and colour Coordinate positioned annotation Several types of annotation are available L Text Any number of lines of text may be plotted in a selection of fonts character heights angles and colours Requires text setting out point to be defined LJ Line Requires start and end points of line to be defined Single or multiple lines may be added in a selection of colours and line styles Q Polygon Requires points to be defined for each vertex LJ Bitmap Adds a bitmap from a selected file at a specified location point 40 Chapter 2 LJ Banner Adds the LUSAS banner at a specified location point LJ Arrow Defines an annotation arrow at specified start and finish points in chosen pen colour Q Symbol A selection of symbols may be plotted in a pt hy selection of sizes angles and colours LI O A x Ty A pa Other Annotation Q Window border Displays an annotated frame around the Window containing the LUSAS version number in use with the model name the date the model title and the model units Q Window summary Window summary annotation is SCALE 1 10 00 added in the form of an automatically assembled text EYE A SOURD 0000 block It displays in
222. dicated by thick lines Torsion is restrained using out of plane beams Overlapping Overlapping beams beams Beams to be attached Beams to be attached 134 Chapter 6 Shell Solid Connectivity Extend the shells over a portion of the solids indicated by the dark shaded area Overlapping shells Shells to be attached Case Study Connecting Shells and Solids Solid and shell elements may be connected but the procedure 1s not as straightforward as it first may appear Solids and shells have different sets of nodal freedoms and the rotational freedom present in the shells can only be passed through to the solid elements by extending the shell around the side of the solid thus passing through the rotation via combined translation effects This form of connection stops rotation relative to a solid which only has translational degrees of freedom The following procedure outlines the general method of fixing shells to solids 1 Define the Surfaces and Volumes 2 Define suitable mesh attributes for example define linear hexahedral elements and linear quadrilateral shell elements and assign these to the Volume and Surface parts of the model 3 Now assign the surface mesh attribute to a surface that forms part of the solid elements and which shares a common edge with the shell Surface that is being fixed to the solid part of the model Do not forget to assign material and geometric attributes to the surface attache
223. dinate Joint local x axes will then coincide with the cylinder radial direction _ Cylindrical Local Coordinate P1 P2 P3 used on Assignment to align Joint Properties Joint Material and Geometric Properties Joint material and geometric properties are assigned to the master feature Q Joint Material Properties Joint meshes require joint properties to be assigned to them These are defined from the Attributes gt Material gt Joint menu item LI Joint Geometric Properties For joints with rotational degrees of freedom an eccentricity must be specified using the Attributes gt Geometric gt Joint menu item Non Structural Mass Elements Non structural mass elements are used to define a lumped mass at a Point or a distributed mass along a Line or over a Surface Variations may be used to vary the mass along the Line or over the Surface Defining and Assigning Non Structural Mass Elements A non structural mass element is defined as a mesh attribute using the Attributes gt Mesh menu item and specifying the structural element type to be used Once defined it is assigned to selected features using the standard drag and drop technique 140 Chapter 6 Non structural mass elements also require material properties to be assigned to them Use the Attributes gt Material menu item to create the required mass for assignment Note Mass properties should be defined per unit length when assigned to Lines and per unit area when assig
224. dinate system is in use the coordinates are specified in the coordinate system of that local coordinate set The dialog box labels will be updated to reflect the required coordinate input Q Cursor Allows definition of a series of Points on the screen with the cursor The Points can snap to a grid in the XY YZ or XZ plane The out of plane ordinate can be specified as non zero if desired This facility is useful for positioning Points on Lines or Surfaces which will be used for splitting that feature later LJ From Mesh Defines a Point at the position of every node of the selected mesh See Geometry From Mesh This is useful for defining a Point feature to which loads or supports can be subsequently assigned The Point must be equivalenced with the underlying meshed feature in order for the Point s assigned attributes to be transferred to the underlying nodes Subsequent re meshing of the structure with different mesh spacing characteristics may result in movement of the underlying nodal positions w LI By Intersection Defines a Point or a number of Points at the intersections of two or more selected Lines When the Lines selected do not physically intersect Points may be created at oO P5 the nearest intersections These nearest intersections are DA controlled by the following options All point pairs creates Points at all possible intersections Nearest point pair only creates a Point on each line where the projection of the Lines
225. e LI Composites A local coordinate may be used to align composite attributes when they are assigned to the model LL Element Orientation A local coordinate may be used at the mesh assignment stage to orient beam and joint elements LI Results Transformation Results can be output relative to a local coordinate For example this is useful when looking at results on elements when the axes are not consistent Local Coordinate Types Cartesian cylindrical and spherical local coordinates are defined by indicating three positions in space defining a local xy plane origin x axis xy plane The type of coordinate chosen will dictate how the axes are defined L Cartesian Based on standard x y and z coordinates arbitrarily oriented in space LI Cylindrical Based on the axes of a cylinder radius angle and distance along the cylinder axis For a local cylindrical coordinate defined along the z axis a point is specified as r theta z where r is the radius perpendicular to the local z axis theta is the angle in degrees measured from the positive x direction of the local xy plane clockwise about the local z axis when looking in the positive z direction Z is the distance along the z axis 249 Y Modeller Reference Manual e Fora local cylindrical coordinate defined along the y axis a point is specified as r y theta where r is the radius perpendicular to the local y axis theta is the angle in
226. e See also acceleration view factor A measure used in a thermal radiation analysis to indicate how much exposure a face has to the radiation emitted from another face A view factor will vary between 0 for no exposure and 1 0 for full exposure virtual work The principle of virtual work states that for any small virtual displacement imposed on a body the total internal work must equal the total external work for equilibrium to be maintained visco elastic A nonlinear time dependent model in which strain is totally recoverable visco plastic A nonlinear time dependent model in which there is a permanent set after unloading viscous damping Damping can be said to be viscous when the damping force is proportional to the velocity See also structural damping volume Feature defining the solid nature of a structure Defined as being bounded by surfaces volumetric crushing model Represents the behaviour of crushable foams and certain soils which exhibit significant volumetric strain It is applicable to plane strain axisymmetric and 3D stress states only von Mises stress The scalar stress state obtained by combining the individual component stresses at a point according to the classical von Mises failure criterion Typically used in the failure of metals Also known as generalised stress equivalent stress warping The degree to which the nodes of a shell element do not lie in the same plane 469 Modeller Reference Ma
227. e This makes contour plots easier to understand and also avoids excessive use of single colour ink when printing Vectors are used to visualise both the magnitude and direction of specified results components Vectors may be displayed at either nodes or Gauss points Scale By default vectors will be scaled such that a vector length of 6mm represents the maximum displayed results component Alternatively a scale factor can be specified 347 Values Modeller Reference Manual Style Vectors may be drawn as lines or arrows By default the colours used for drawing vectors in tension and compression are red and blue but the pens can be altered as required Deformed Shape This image shows displacement vectors displayed on the deformed shape FE y F 4 i i Fg 4 ty Hy ln ni te I y Values are used to identify the location and value of results for both averaged nodal smoothed element nodal unaveraged and Gauss point values Either maximum and or minimum values may be visualised and a percentage may be specified to determine whether values lying within a maximum minimum range are displayed Values may also be displayed at selected nodes The Values layer is also used to display the locations of yield symbols and crack crush planes Maximum and minimum values marked Values plotted for selected shrunk elements Visualisation of yielded material Visua
228. e number of increments Within each increment a linear prediction of the nonlinear response is made and subsequent iterative corrections are performed in order to restore equilibrium by the elimination of the residual or out of balance forces Load Equilibrium Iterations Displacement 284 Chapter 7 The iterative corrections are referred to some form of convergence criteria which indicates to what extent an equilibrium state has been achieved Such a solution procedure is therefore commonly referred to as an incremental iterative or predictor corrector method shown in the figure above In LUSAS the nonlinear solution is based on the Newton Raphson procedure The details of the solution procedure are controlled using the nonlinear control properties assigned to loadcase For the analysis of nonlinear problems the solution procedure adopted may be of significance to the results obtained In order to reduce this dependence wherever possible nonlinear control properties incorporate a series of generally applicable default settings and automatically activated facilities iterative Procedures In LUSAS the incremental iterative solution is based on Newton Raphson iterations In the Newton Raphson procedure an initial prediction of the incremental solution is based on the tangent stiffness from which incremental displacements and their iterative corrections may be derived Standard Newton Raphson Procedure In the sta
229. e the surface may translate and or rotate but remains plane Nodal positions may vary relative to other nodes on the surface This type of constraint is only valid for small displacements In this example a planar Surface constraint is assigned to the top Surface to force the underlying nodes to remain planar during loading Constrained nodes may move relative to each other as long as they remain in plane Q Straight Line A straight line may be constrained to remain straight the line may translate and or rotate but will remain straight Nodal positions may vary relative to other nodes along the line This constraint type is only valid for small displacements In the example shown a straight Line constraint is assigned to Line 3 to force underlying nodes to remain in a straight line relative to each other during loading Constrained nodes may move relative to each other as long as they remain in a straight line Cyclic LI Cyclic Rotation Cyclic rotational symmetry may be used to model a section from a continuous ring Master WY i A The mesh on the two planes of symmetry may be different In the example shown the radial Lines j are defined as a Master and Slave pair maintaining aa cyclic symmetry around the structure Meshes on the Master and Slave Lines need not match Q Cyclic Translation Cyclic translational symmetry may be used to model a section from a continuous strip The mesh on the two planes of sym
230. e added to the view of a model from the View gt Insert Layer gt Labels menu item or from the window context menu The label options are controlled from the labels property dialog Labels may be added to geometry features as follows LI Name Q Position LI Mesh LI Geometry Q Material L Supports Q Loading LI Transformed freedoms LI Composite 0 Slideline LJ Constraints 74 LI Thermal surfaces LI Retained freedoms Q Damping LI Activate LI Deactivate LI Equivalence LI Search area LJ Influence LI Age LI Tendon Chapter 4 Node element and Gauss point labels may also be displayed Notes e Line labels for standard Lines are drawn at 3 4 distance from the start of the line This can be a useful indication of the line orientation e Ifa Line is used as part of a Combined Line definition the Line label is located at 8 10 distance and the corresponding Combined Line label is located at 6 10 distance along the Line segment This is to avoid the labels overwriting each other e For complex models labels may be displayed only on selected features by choosing the Label selected items only option on the label properties dialog Points Points define the vertices of the model Point definition commands are found under the Geometry gt Points menu item Points can be defined in the following ways LI Coordinates Defines a Point by entering the X Y and Z coordinates Z is optional If a non Cartesian local coor
231. e animation sequence relative to the others The spread of stress or other entity can then be seen more readily ee Pp g When animating deformed models it is recommend that the resize button lt l 1S switched off before creating the animation to prevent re scaling during the animated sequence 369 Modeller Reference Manual e Animation is carried out using pixel dumps hence a complicated picture is no more time consuming to display than a simple picture but may take more time to assemble initially However increasing the number or size of segments will require a proportionately larger amount of memory e The only model loadcases that is those loadcases that are saved with a model available for inclusion in an animation are basic modelling loadcases and basic load combinations Envelope and Smart Combination loadcases that are saved with a model cannot be animated e When animating staged construction models the mesh layer display should be set to Show activated elements only in order to see the model building sequence Controlling the Animation The buttons at the bottom of the animation window allow the animation to be speeded up or slowed down stepped frame by frame and looped The 1 1 button controls the aspect ratio when the window is resized Saving Animation Files Animation files may be saved as Windows standard avi files using the File gt Save As AVI menu item The avi format can be viewed by double clicking on
232. e as displacements increase e g the snap through of a shallow arch In this instance the structure may not have failed completely and could subsequently still be capable of carrying more load A bifurcation point indicates that the solution of the nonlinear differential equations has encountered an alternative unstable solution path or paths which may be followed instead of the stable equilibrium path The branch switching procedure must then be undertaken if an unstable equilibrium path is to be followed The branch switching procedure should only be carried out within a restart analysis after bracketing has been successfully completed Two options exist for guiding the solution onto a secondary path LI EKigenmode injection LJ Artificial force and Rheinboldts arc 28 Modeller Reference Manual Incremental Loading Incrementation for nonlinear problems may be specified in four ways Q Manual Incrementation where the loading data in each load increment is specified separately LJ Automatic Incrementation where a specified loadcase is factored using fixed or variable increments LJ Mixed Incrementation Mixed manual and automatic incrementation LL Load Curves where the variation of one or more sets of loading data is specified as a graph of load factor vs load increment or time step The choice and level of incrementation will depend on the problem to be solved Automatic Load Incrementation Two methods of automatic increme
233. e created by importing finite element data files created either by the prior running of an analysis in LUSAS or more usually by importing data files from other supported third party software applications Use the File gt Import Mesh menu item to do this When a file is selected the Advanced button can be used to specify import parameters During the mesh import process Modeller creates separate Groups for each element type encountered For models created from LUSAS data file these will be familiar LUSAS element names For models created from other software they will be the names used within that system whatever they may be See Mesh only models for more information After import the vertical axis for the model may need to be defined to ensure correct isometric viewing and loading of the model See Mesh only models for more information File Import Mesh options Advanced Only those options applicable to the file being imported will be available for selection Option Description Default Create Create named groups for elements in the data file having the same material False material property A maximum number of groups can be specified and if more groups groups are created the number specified only the most common element groups in the model will be created This option is for use with LUSAS Solver data files and Nastran bulk data files only Exporting Model Data Model data can be exported to a chosen interface file format by using the
234. e for the element e When rubber materials are utilised the value of det F or J the volume ratio is output at each Gauss point The closeness of this value to 1 0 indicates the degree of incompressibility of the rubber model used For totally incompressible materials J 1 0 However this is difficult to obtain due to numerical problems when a very high bulk modulus is introduced for plane strain and 3D analyses e Subsequent selection of state variables for displaying will include the variable PL1 which corresponds to the volume ratio e Rubber material models are not applicable for use with the axisymmetric solid element QAX4M since this element does not support the co rotational geometric nonlinear formulation The use of total Lagrangian would not be advised as an alternative e There are no associated triangular tetrahedral or pentahedral elements for use with the rubber material models e The rubber material models are inherently nonlinear and hence must be used in conjunction with nonlinear control command e The rubber material models may be used in conjunction with any of the other LUSAS material models However it is not possible to combine rubber with any other nonlinear material model within the same material attribute 181 Modeller Reference Manual Volumetric Crushing Model 81 Material behaviour can generally be described in terms of deviatoric and volumetric behaviour which combine to give the overall material r
235. e g 3 N mm LJ Strain at peak uniaxial compression e g 0 0022 LI Strain at effective end of softening curve for distributed fracture e g 0 035 or 0 if G0 Q Fracture energy per unit area Gp e g 0 1 or 0 if e gt 0 Q Biaxial to uniaxial peak principal stress ratio B e g 1 15 172 Chapter 6 Q Initial relative position of yield surface Z e g 0 6 Q Dilatancy factor giving plastic potential slope relative to that of yield surface y e g 0 1 L Constant in interlock state function m e g 0 425 LI Contact multiplier on for 1st opening stage mj e g 0 5 Q Final contact multiplier on Mp e g 5 LJ Shear intercept to tensile strength ratio for local damage surface ro e g 1 25 U Slope of friction asymptote for local damage surface u e g 1 Q Angular limit between crack planes radians e g 1 Explanations for some of these suggested values are stated in the notes that follow Notes e The model can be used with 2D and 3D continuum elements 2D and 3D explicit dynamics elements solid composite elements and semiloof or thick shell elements e If no data for the strain at peak compressive stress is available it can be estimated see Solver Reference Manual for details As a guide a reasonable value for most concretes is 0 0022 e Itis important that the initial Young s modulus E is consistent with the strain at peak compressive stress e A reasonable check is to ensu
236. e gt Model Properties menu item but note that changing an interface type will not remove any properties created and assigned to the model when using the previous interface Within LUSAS consistent units must be used A wide range of consistent units is available from the units drop down list By selecting a startup template useful predefined attributes can be setup in the model User defined startup templates can be created and accessed via the button alongside the Startup template drop down list The vertical axis used to orientate the model define a default gravity loading direction and the vertical axis and orientation of particular element types and library items such as steel sections is set on the New Model dialog It may be changed subsequently using the Utilities gt Vertical Axis menu item Model Types Two types of model can be created in LUSAS Q Feature based geometry models these are based on defined features such as points lines surfaces and volumes or are created from imported geometry and require the definition of mesh objects such as elements with their associated nodes Prior to version 14 7 of LUSAS these were the only model type available in LUSAS LJ Mesh only models these comprise only mesh objects elements and their associated nodes edges and faces and are created by importing only those types of LUSAS or third party data that are supported Initial support for these models was introduced in version 14
237. e is subsequently visualised using the fleshing 4 option For most other cases cross sectional information is automatically provided or created by LUSAS In defining the cross section shape the coordinate of each quadrilateral must be defined in local zy cross section coordinate pairs at each node zl yl z2 y2 Z3 y3 z4 y4 When defining a cross section by this method 148 Chapter 6 the centroid of the section must reside at 0 0 For Cross Section Beam elements for advanced use only the number of integration points also known as gauss points can also be set Q Fibre locations define positions on the beam cross section at which stresses can be plotted when visualising results Standard sections precast beam sections and box sections added to a library will have their cross sectional geometry pre defined They also have default fibre locations stored for each section Sections drawn by users and added to the local user or server all users libraries using the arbitrary section property calculator have fibre definitions calculated automatically L Plastic properties geometric properties are required for beams when using the stress resultant material model model 29 Ap Plastic area elastic area Zyyp Plastic modulus for bending about y axis Zzzp Plastic modulus for bending about z axis Zyp Plastic modulus for torsion about y axis Zzp Plastic modulus for torsion about z axis Sp Plastic area for sh
238. e limit points are encountered LUSAS will automatically determine the sign of the next load increment by the sign of the determinant of the stiffness matrix This is a reliable method in most cases however it will often fail in the vicinity of bifurcation points when negative eigenvalues may cause premature unloading In such cases the load reversal criteria may be optionally changed to be dependent on the sign of the current stiffness parameter This method is better at coping with bifurcation points but will always fail when a snap back situation is encountered Note In certain circumstances notably in the presence of strain softening the arc length method may converge on alternative unstable equilibrium paths Bracketing Critical Points And Branch Switching Bracketing can be used to locate a limit or bifurcation point during a geometrically nonlinear analysis The nonlinear analysis is executed and one of three methods is used to isolate the first critical point 0 Bi section LI Interpolation LI Riks semi direct approach Two further options for the bracketing procedure exist depending on whether the material response is elastic reversible or plastic path dependent irreversible Only the first critical point can be processed and a subsequent eigenvalue analysis must be invoked to determine whether the critical point encountered is a limit or bifurcation point A limit point may be defined as the point at which load starts to decreas
239. e model was saved this is not re opened automatically when the model is re opened later Customising the Environment Various user definable settings and facilities allow the interface to be customised LJ Window properties contain options relating to the current window LI Startup templates can be used to pre load the Attributes Treeview of the interface with selected attributes for a particular analysis set default mesh or material types or define preferred colour schemes to name just a few uses 42 Chapter 2 Q Toolbars and toolbar buttons can be customised and user defined toolbar buttons can added to the user interface either to sit on a new toolbar group or alongside existing buttons in an existing group Window Properties The Window Properties dialog shows options relating to the current window Window properties may be displayed by double clicking in a blank part of the graphics area with no features selected or by right clicking a window in the H Treeview and then selecting Properties from the context menu Window properties define basic view information L General Show or hide the screen ruler selection tolerance and enables the window background and selection colours to be modified Q View Shows the view rotation vector and rotation increment Provides isometric projection Enables the scale and origin position to be set and allows the current view settings to be saved LI View axes Controls whether and at wha
240. e more slack the minimum energy requirement 285 Modeller Reference Manual Separate Iterative Loops In problems where both material and contact nonlinearities are present convergence difficulties can arise when evaluating material nonlinearities in configurations where the contact conditions are invalid because the solution is not in equilibrium To avoid this situation contact equilibrium can be established using elastic properties from the previous load increment before the material nonlinearity is resolved The option to define separate iterative loops is defined on advanced solution strategy dialog which can be found on the nonlinear control dialog See the Theory Manual for further details Incremental Procedures For the Newton Raphson solution procedures it is assumed that a displacement solution may be found for a given load increment and that within each load increment the load level remains constant Such methods are therefore often referred to as constant load level incrementation procedures However where limit points in the structural response are encountered for example in the geometrically nonlinear case of snap through failure constant load level methods will at best fail to identify the load shedding portion of the curve and at worst fail to converge at all past the limit point The solution of limit point problems therefore leads to the development of alternative methods including displacement incrementation a
241. e other standard loads Inertial loads are calculated from element volumes and applied accelerations The specification of linear accelerations angular velocities and angular accelerations is enough to define the forces acting on the structures since the element volume and density from which the mass is calculated are element properties Depending on the input data loads are applied for the n 0 1 2 harmonic components However the body force data must still be associated with a dummy load curve and must be declared in the first loadcase In addition to the input accelerations angular velocities and angular accelerations you can input an offset origin about which the rotations are applied The local rotation about the finite element axis of symmetry should not be confused with the global rotation about the global axes The local rotation implies that the body is rotating with respect to the finite element axes while the global rotation is a rigid body rotation of the complete finite element model For further details see the Theory Manual Centripetal Load Stiffening Centripetal load stiffening has been applied to the n 0 harmonic but there is no nonlinear stress stiffening contribution Special Application to Non Axisymmetric Structures In some instances the structure may not be truly axisymmetric but it may be desirable to obtain an approximate response from an axisymmetric analysis An example of this is a turbine where the turbine axis is
242. e patch load is automatically split into point loads 8 The number of discrete loads in each direction is dependent on the numbers of divisions entered in the Assign Loading dialog In this case the default number of divisions 10 is insufficient as there are insufficient loads to apply at least one load per element along the culvert To improve the load application accuracy deassign the load from the Point and reassign using 15 divisions in the local X direction Leave the Y divisions field blank Note that LUSAS has automatically used the aspect ratio of the patch load to calculate a suitable number of divisions in local Y 208 Chapter 6 A VAA x VA x A A D A e AAAA VV KX A y v x A LUVA VA X V AYNA Y AOA Y A XV X VA A AAA AAA AAA AAA AAA AAA AAA A AAA AAPA AAA AAA AMAA AAPA PA PA AAAAAAAAL NAZLZLAAAAA LEVEL K a ik SS i he S a AAAA LAA gt b gt S AAAA AAAA AAAA AA AAA NAAAZLAAAA Search Areas Search areas may be used to restrict the area of application of discrete loads point and patch This is useful for several reasons LI Improved Control of Load Application The search area will effectively limit the area over which the load is applied so that the effect of loads on certain features may be removed from the analysis For 3D models it is possible that a chosen projected direction will cross a model in several locations A search area is therefore u
243. e points in space to define an arbitrary plane or two points to define a plane parallel to either the Z Y or X axis Three Points added to selection memory can be used to define an arbitrary mirror plane and two Points added to selection memory can be used to define a mirror line in the XY plane not the YZ or ZX planes Note Care should be taken when mirroring Lines and Surfaces as their orientations may be reversed so some Surfaces may effectively be turned upside down Lines may also point in the opposite direction See Changing Geometry Orientation to resolve any problems 101 Modeller Reference Manual Q Scale A scale factor and the origin point of the scale is specified LJ Matrix rotation A direction cosine either specified directly or using two D p or three Points added to selection i memory Points in selection memory define a plane the rotation of the global XY plane to this new plane defines the transformation Note If the determinant of the matrix is not unity then the effects may not be as Zz desired This example defines a rotation by defining a plane relative to the global Cartesian axis set by indicating three Points at the origin P1 along the local x axis P2 and defining the local xy plane P3 The resulting transformation is a rotation of 90 degrees about the global axes Notes e Ina transformation dialog including the move copy or sweep commands click on t
244. e process of viewing the analysis results post solution Any part of the finite element solution process following the computation of the displacements for example strain stress moment recovery and output phases power law A creep formulation using three material parameters which include primary secondary and tertiary regions of creep behaviour See also strain hardening 455 Modeller Reference Manual pre conditioned conjugate gradient solver Iterative solution using a conjugate gradient solver is very sensitive to the matrix conditioning For this reason the matrix is usually pre conditioned before solution pre processing The process of building the model ready for analysis pre solution Any part of the finite element solution before the solution of the displacements It is usually associated with the formation of elemental stiffness matrices and load vectors prescribed variable The specification of the value of a nodal displacement or of a differential of nodal displacement with respect to time Chiefly used to prescribe displacement values pressure dependent yield Plastic deformation where the amount of plasticity is dependent on the sign of stress tension compression For example Hoffman modified von Mises material models pressure loading Loading expressed in per unit area or unit length terms primary creep The initial nonlinear part of the creep curve principal stress vectors Vector plot showing
245. e specification of convergence therefore involves two considerations e Type of convergence criterion e Convergence tolerance The types of convergence criteria incorporated in LUSAS are as follows LI Absolute residual norm Q Root mean square residual norm LI Displacement norm LI Residual force norm 0 External work norm LI Incremental displacement norm The convergence tolerance for each criteria is specified in the Solution parameters and advanced solution parameters section of the Nonlinear Control properties The selection of a convergence criteria and the associated tolerance is problem dependent However the following points should be considered Clearly the convergence criteria must not be too slack so as to yield an inaccurate solution nor too tight so as to waste computer time performing unnecessary iterations In general sensitive geometrically nonlinear problems require a tight convergence criteria whereas with predominantly materially nonlinear problems larger local residuals may be tolerated Where more than one criteria has been specified convergence will be assumed only on the satisfaction of all specified tolerances The following considerations apply to individual convergence parameters LI Absolute Residual Norm is of limited use owing to its dependence upon the units being used It is a strict criteria and for some problems especially those involving plasticity it may be very difficult to reduce locally
246. e specified to act as one complete transformation In this example Line 1 is created by sweeping Point 1 in a translation in X and Y LI By Offsetting Defines a Line which is offset parallel to a selected Line An additional Point may be selected to define the plane in which the new Line is to be defined If multiple Lines are selected the outside fillets may be created with arcs or straight Lines Pd L2 P4 Pl P2 PI L3 P8 L1 L2 Py Y Translation L1 Pl 117 Modeller Reference Manual LI By Joining Defines a number of Lines by joining two sets of Points The Points in selection memory define the start of each Line the 3 1 L1 7 4 Points in selection define the end of i each Line The Points should pair up equally Lines are joined according to P2 i l2 P5 the order in which the Points were a selected or Point number when boxing a selection i e first point in selection memory joins to first point P3 L3 P6 in the selection etc In this example Lines 1 to 3 were defined by first 2 ee adding Points to 3 to selection Add to R memory then selecting Points 4 to 6 selection memory Select with cursor and then using this command LI By Intersection Lines may be defined by intersecting two or more Surfaces Intersects all Surfaces within a single selection with all other Surfaces within that selection If no
247. e status of all new features to Unmergable rather than the default which is Mergable e Tolerance controls the distance within which Point features must lie before they will be considered for merging Note The merge tolerance should only be changed with extreme caution because changing it from its default value can lead to instability of the underlying geometry engine See Merging Features for more details L Active Local Coordinate Sets the coordinate system as either the Global coordinate or any defined local Cartesian cylindrical or spherical coordinate If a local coordinate is set activate then all subsequent geometry definition is carried out in transformed coordinates Advanced Geometric Properties LI Splitting Defaults The state of the splitting defaults may be set from the advanced geometry dialog for all operations involving splitting operations The defaults control the check box state and may be overridden during geometry creation 19 Modeller Reference Manual Q Creation Defaults Process objects in selection order forces objects to be processed in selection order rather than Modellers best fit Allow hollow volume creation allows hollow volumes to be created This option is automatically set true when IGES files are imported Once set the create volume button will try to create a closed hollow volume when it is not possible to create a solid volume In addition extra menu items will appear under the Geometry gt
248. e strain Explicit dynamic axisymmetric Interface Notes Triangle 3 noded TPM3 TPNS TAX3 TF3 TS3 TTS3 TSM3 TAX3F TFD3 TXF3 TPM3E TPN3E TAX3E Quad rilateral 4 noded QPM4M QPN4M QAX4M QF4 QSC4 QSI4 QTS4 SMI4 QAX4F QFD4 QXF4 QPM4E QPN4E QAX4E Triangle 6 noded TPM6 TPN6 TAX6 TTF6 TSL6 TTS6 TAX6F TFD6 TXF3 Quadrilateral 8 noded QPM8 QPN8 QAX8 QTF8 QSL8 QTS8 QAX8 QFD8 QXF8 IS16 e Elements in bold text are only available if your licence includes the Plus option e No check is made in LUSAS Modeller as to whether the element type is valid for the analysis being performed however LUSAS Solver will stop the analysis if the element is unsuitable e This list is a guide as to which elements to use Not all elements are listed here See the Element Reference Manual for full details of all elements Volume Element Selection The following table lists the elements available for volume meshing by type and by name The first column matches the option list in the Volume mesh dialog box Generic Element Types Stress Thermal Explicit dynamic Stress composite Thermal composite Tetrahedral 4 10 noded noded TH4 TH10 TF4 TF10 TH4E 146 6 noded PN6 PF6 PNGE PN6L PF6C Pentahedral 12 15 noded noded PN15 PF15 PN12L PN15L PF12C PF15C Chapter 6 Hexahedral Generic Element 8 16 20 Types noded noded noded Stress HX8M HX20 Thermal HF8 HF20 Exp
249. e using a specified frequency step The results type required will be Amplitude Modal response calculations are carried out as follows 1 Read in the results file from the eigenvalue analysis Use File gt Open and specify the results file name Click on Utilities gt Graph Wizard Choose Modal Expansion then click on the Next button Click on Frequency to specify the frequency domain Choose a Point force excitation then click on the Set button to define the parameters Excite the structure at the unsupported end node in the Y direction Enter the node number or if the node is selected choose the number from the drop down list Click on the OK button then click on the Next button Specify the results entity as Displacement component DY and the results type as Amplitude Take care to specify a realistic start end and frequency step Specify which node to calculate the response at then click on the Next button Specify a Title and X and Y axis labels then click on the Finish button This will create a standard frequency vs amplitude plot for the response from the specified excitation Two graph datasets will be created the first containing the frequency range in the steps specified and the second containing the required amplitude values User Defined Results Defining expressions The User Defined Results dialog is accessed from the Utilities gt User Defined Results menu item It allows results components to be defined b
250. e varying section line attribute to the set of lines When assigning a geometric line attribute the following transverse direction settings are available LI Perpendicular to path the plane of constant distance is normal to the path tangent in both local y and z directions LI Skew angle is defined as the horizontal angle between the orthogonal plane and the plane of equal distance Q Local coordinate as skew angle but where the skew angle is read from an existing local coordinate system 269 Modeller Reference Manual Skew angle to path Y 2 0 3 0 4 0 5 0 Zz x Reference path Reference path Perpendicular Skew angle to path Align to Y axis of local coordinate system x Reference path Local coordinate Visualisation of reference paths By default reference paths are drawn in red and points defining the path are labelled with their absolute distance along the path of lines The display of path labels can be turned on and off by accessing the Utilities layer properties dialog Direction arrows at mid points along each line segment show the direction of the path Each path entry in the Utilities treeview has a context menu enabling the following selections LJ Rename changes the path name LI Delete removes the path entry from the Utilities treeview but the menu item is only available if a path has not been associated with a geometric line assignment LI Edit Path displays the path definition dialog
251. ea Patch load Patch load 215 Modeller Reference Manual Full Load All patch loads lying outside the search area dark area are lumped at nearest loading positions within the search area light area Patch load Discrete point loads over areas When discrete point loads are defined by specifying a grid of points they can either be excluded from the search area or be projected to be included into the search area in exactly the same way as for discrete patch loads If discrete point loads are defined by the Arbitrary option and if the points are defined in an identifiable grid format then the loading is applied as per the patch loading that is the loading components can be projected along the columns and rows of the patch load grid into the search area otherwise the loading is applied to the nearest load location in the search area Discrete point loads into volumes When discrete point loads are projected into volumes by being assigned to a particular point on or within the volume the applied discrete loads are extrapolated within the elements to create equivalent concentrated nodal loads When search areas are assigned to volumes the following options are available LJ Exclude All Load default patch load components outside the volume will be disregarded and all load components within the search area will be extrapolated within the elements to create equivalent concentrated nodal loads LI Include Full Load pa
252. ear Sp 0 The actual parameters required depend on the chosen beam element See the Element Reference Manual for further details Once defined the geometric section properties are added to the ob Treeview using the OK or Apply button The geometric properties can then be assigned to the required Line s in the model Offsets Beam Centroid e Thick beam elements accommodate Bending Plane Offsets which are measured from the bending plane to the nodal line in the y local element direction When offsets are defined the beam section properties are input relative to the y beam axis Offset ve o x e When sections are defined at either _ re Nodal ends of a tapering beam the offset of one section to the other to achieve the vertical and horizontal alignment setting Beam Local Element Axes 149 Modeller Reference Manual Notes specified is automatically calculated Subsequent entering of an offset value for the master end in the Value field will automatically offset and update the value for the other follower end by an equivalent amount to ensure the beam ends are moved equally from their nodal positions If a vertical or horizontal alignment offset is stated in the Alignment panel of the dialog that value will only affect the follower end For thin beam elements eccentricity may be incorporated within the geometric properties In this case the properties are input relative to the nodal line This ty
253. ecccsdenocwesdoncctecssssnncblbiecucadextceebssccuoendsasecsiaincues 281 Nonlinear Solution Procedures snnsoonnnsnssnnnnonnnnnoonnnnsennnnnnnnnuonnnnnnssnnnnnnnnnenannnsnsnnnnnnnn 284 Creep Viscoelastic Analysis ccccssssessceeeeeeeeeeeeeeeeeeeeeseeeeeeeeeeeeeesseeeeeneaeaseseeeeeeeesessenennons 291 EIGe n Value Analysis is ceccincnccceiseccacasicetenassetvenedieseewassecuauarsdeiewcovateenediouscsecsevancoushiatcesecvascdeshs 292 Eigenvalue Buckling Analy SiS isisisi aeaa a iea indeed 298 Spectral Response AnalySIS wiscieseccsecessscases cocataneceeeeacessestseeseecessnebeetewewsessanasecctcavadmeeteesteetes 299 Transient Dynamic Analysis soisi e caste a a aeaa aae ddesieaustasamenaduvia aa eenaa aiee 300 Impact Dyna MiC Sesser iison ena dearena ra aa aeeie a earan oca aaaea 302 Coupled Analysis soana aE AA EEKANNA E ANANS E DEA EAEAN SAE ER 302 Field ANAYSSI Sisia a e a a hea ee ce a ea Ea EEEa ESEE 304 Steady State Thermal ANalySIS siioni aiian cteccacscauanaininvicctuieweuaiacduceaiuivvavenwenwceetiens 305 Transient thermal ANalySiS siorino ioei aaaea aeaa aiaa aaae aaa aaa aani 305 Fourier Analysis crise a eao REE aa ea AOE EEES 307 Frontal Optimisation and LUSAS Soler S ccccccccceseseseeeseeeeeeeeeeeeeeeeeeeeeeeeeeseesneneeeeeeens 309 Support with Modelling and Analysis Problem ccccceceeeeeeeeeeeeeeeeeeneeeeeeeeeeeeseeeeenes 312 Pre Analysis Checks ssnnnooonnensennnnonnnnnoosnnneonnnnnnnnnnnno
254. echanical coupled analysis 302 Thickness 151 thin beam elements 150 Tied slidelines 234 time history 339 Tip 415 Tips 415 TMPE loading 197 toolbar buttons user defined 46 toolbar groups 45 customising layout 46 toolbars 45 TPDSP loading 218 transformations 99 322 transient analysis 300 302 305 translating geometry 99 treeview 9 Tresca material model 169 trimetric 413 troubleshooting 399 trouble shooting 406 two phase analysis 179 190 U UDL loading 196 UK steel sections 153 undo redo 39 uniformly distributed load 196 units 279 US steel sections 153 User 153 utilities 257 Index Y values 348 yielded material visualisation 352 variations 258 vbs 53 vectored results plots 343 vehicle loading 201 Zoom 411 velocity loading 200 zooming 37 vertical axis 273 view 26 411 viscosity 165 178 Viscous dampers 187 viscous damping 223 visual basic 53 Visualise 148 visualise users 116 visualising 70 118 222 343 353 365 369 371 contour plots 346 deformed mesh 345 results 343 353 365 368 Visualising composite properties 247 volume elements 146 volume feature 69 92 volumetric crushing material model 182 von Mises material model 167 168 W Window Properties 43 windows 26 413 WMF 375 Wood Armer 330 481 Z Modeller Reference Manual 482
255. ecifying a radius and Minor Arc Alternatively Line 4 is created by selecting Lines 1 and 2 then specifying a different radius and Major Arc LI By Sweeping Points Defines Arcs by sweeping selected Points through a specified rotation In this example Li Point 1 is swept into Line 1 using a rotational transformation and choosing the Minor Arc option P3 PI 80 Chapter 4 Spline Definition Spline Lines are defined from the Geometry gt Line gt Spline menu item LI By Points Defines a spline from three or more selected Points L Points and End Tangents Defines a Pl Spline passing through two or More ee Li selected Points The end directions are P defined by entering end tangent vectors In this example Line 1 is defined by specifying Points 1 2 and inputting start and end tangents by vectors 1 0 0 and 0 1 0 respectively Both the direction and length of the end tangents control the spline shape In this example a different shape of spline would be defined passing through the same Points if the end tangents were changed to 3 0 0 and 0 0 5 0 respectively LI Tangent to Lines Defines a Spline passing through two or more selected Points The Spline end vectors are taken from the directions of two selected Lines The tangent Lines do not have to connect with the Spline In this example Line 3 is defined by selecting Points 2 3 4 5 to define the path and Lines 1 and 2 as end tangents Spl
256. ecifying a transformation that will rotate the loads out of the vertical direction and into an inclined plane in the direction of vehicle travel Q Search area A search area restricts loading to a specified portion of the model If a search area is not specified the load is projected onto the whole model For 2D models it is usually acceptable to default to the whole model but for 3D models where multiple intersections of the load projection onto the model may occur it is safer to restrict the loading to the required face using a search area In either case the time taken to assemble the loads is significantly improved by using a search area to restrict the number of elements tested for intersection with the load Search areas are automatically created and used by the prestress wizards to define the target to be loaded In addition the discrete load can be specified to LI Project onto line This option is used to project discrete loads onto 2D line beam structures and frame models Discrete loading is applied to the beam as corresponding forces and moments along the beam LI Project over area This option is used to project discrete loads over an area The area may be defined by a grid of beam elements a grillage a plate or shell structure slabs or the face of a solid model LI Project into volume This option is used to project discrete loads into volumes solid models and is primarily for use with tendon loading 206 Chapter 6 L
257. ection but the section shape created must always be continuous The use of the menu option Geometry gt Surface gt Holes gt Create will effectively punch a hole into an existing surface A Boolean subtraction of a smaller surface from a larger surface would also produce the same result Grouping all holes together into a group named Holes is optional for cases where a single surface contains one or more holes totally inside its boundaries Grouping all holes together into a group named Holes is essential if a hole exists between two surfaces See diagram When present the properties of a group called Holes are automatically deducted from the overall section property calculation Void Surface A Surface B Surface defining a cross section containing two Two surfaces defining a cross section with a hole between holes surfaces 2 6 Chapter 6 Automatic meshing is normally used to control the mesh density which in turn is used to calculate the section properties The maximum elements to be assigned to any one line helps control the density of the automatic mesh used To use the computed section properties in a model the section must be saved to a local or server library To add a library item to the Attributes b treeview select the Attributes gt Geometric gt Section Library menu item then select User Sections then select Local or Server before choosing the section required from the list available The geometric properties can t
258. ection menu item and box selecting around selected points to see if more than one point appears in the list shown e The equivalence tolerance must be less than the smallest distance between two nodes on the same feature otherwise the equivalencing operation will fail e Equivalencing may be used to position a point load or support at a node which is not at a defining feature Point A Point must be created the load or support assigned and the Point and meshed feature equivalenced e Equivalencing may be used to merge nodes on the constituent Lines of combined Lines i e the nodes on an entire combined Line may be equivalenced including the Lines forming it Age attributes define the age in days between creation and activation of features in the model and are used in conjunction with the CEB FIP Concrete Material Model When assigned to a feature all elements created by that feature are assigned the specified age Age attributes are defined from the Attributes gt Age menu item See Solver Reference Manual for further details 222 Chapter 6 Damping Damping is used to define the frequency dependent Rayleigh damping parameters for elements which contribute to the damping of the structure Viscous modal and structural hysteretic damping can be specified If no damping attributes are specified the properties are taken from the material properties click on dynamic properties on the elastic page of the material attribute dialog
259. ects are required the thermal surfaces defining the gap must be specified on the Thermal Gap properties dialog Q Radiation Surfaces Diffuse radiation exchange may be modelled with a radiation surface that is defined by any number of thermal surfaces Planes of symmetry that cut through the radiation enclosures may be defined so that it is not necessary to model the whole structure Radiation surfaces allow for the calculation of diffuse view factors These view factors may be output to a print file Specifying thermal surfaces defining a gap Pre defined thermal surfaces can be selected on the Thermal Gap properties dialog in order to define a gap The gap can be defined as active or inactive initially and be set to change according to loadcase Choosing Thermal Properties Radiation Surface Utilities gt Heat Transfer gt Radiation Surface Controls heat transfer from body to body over large distances where radiation is dominant Thermal Surface Attributes gt Thermal Surface Assign to features Used to associated heat transfer properties with parts of the model Thermal Gap Utilities gt Heat Transfer gt Thermal Gap Controls heat transfer from body to body in close proximity where conduction and convection are dominant The following flowchart guides the decision making process for choosing thermal properties The process is simplified if the analysis only considers a single
260. ects specified by the number of Variable loadcases to consider The remaining positive load effects will only use the permanent factor The number of load effects summed is restricted to the number of loadcases specified and the other loads are discarded The loadcases used are the most adverse for example the most positive are used for a maximum combination and all other load effects assembled are discarded Also with the variable loadcases set to four the max combination will include only positive load effects all negative load effects are discarded 393 Modeller Reference Manual Nodal Loadcase result Temperature 5 Wind 5 s Settlement 10 Live load 1 20 Live load 2 15 Live load 3 10 Live load 4 5 Permanent factor 0 7 0 7 0 7 0 7 0 7 0 7 0 7 Variable factor 0 8 0 8 0 8 0 8 0 8 0 8 0 8 Factor used for maximum combination 0 7 0 7 0 7 0 7 0 7 0 7 0 8 0 7 Factored nodal results 5 x 0 7 3 5 5 x 0 7 3 5 10 x 0 7 7 20 x 0 7 14 15 x 0 7 10 5 10x1 5 15 5 X 0 7 3 5 Smart combination Max 15 Not used Not used Not used Not used Not used Used Not used Smart combination Min will assemble results from the loadcases using just the permanent factors given for positive load effects and using permanent variable factors for negative load effects for number of negative load effects specified by the
261. ed unlipped double back to back double face to face top hat Q Z section lipped right angle lipped inclined unlipped Rectangular Solid Section Property Calculator m Dimensional data Calculated properties p os a ps 5 B 0 3 E 3 1258 3 Fibre 2 Fibre 4 Ixy E 0 J 2 81 737E 3 Asy 70 125 H 4 0 125 ibre ibre Name Rs D 0 5 B 0 3 jhe oe Add to local library Est c Visuali onh xisting sections teate geometry Isualls Create annotation Cancel Apply Help Typical standard section property calculator dialog Section visualisation showing fibre locations Section properties for standard cross sections are computed instantaneously once valid user defined dimensional data has been entered The resulting section can be optionally visualised to check for correct values being entered and to see automatically defined fibre locations as used when plotting stresses on fleshed beams or be converted into model geometry if the section was to be modified in some way inside LUSAS Modeller before re calculating the new section properties of the edited section using an Arbitrary Section Property Calculator or be added to a local or server library for use on the current project or for re use across other projects To use the computed section properties in a model the section must be saved to a local or server library To add a library item to the Attributes gt treeview select the At
262. ed B matrix and D matrix if a nonlinear material has been specified 408 Appendix C Appendix C Keyboard Shortcuts Keyboard Shortcuts Selecting Model Features Features displayed in the graphics window may be selected using either specific cursors or by using normal cursor mode in conjunction with specific keys Feature Mesh Object Selection Options Hold the key shown down when using the left mouse button Specific cursor Normal cursor key at All geometry selection G key hol Point selection k P key Ls Line selection L key hol Surface selection S key Ro Volume selection k V key ho Mesh selection M key La Node selection k N key LA Edge selection k B key 409 Modeller Reference Manual Face selection k F key 1 Element selection E key hal Annotation selection A key Note Key shortcuts can be used to override specific cursor selections Area Selection Options Rectangular circular or polygonal areas can be selected by using specific area toolbar buttons or by using normal cursor mode with a specific key Specific cursor Normal cursor key _ w Click and drag the cursor to the opposite diagonal corner k Click the centre of the circle and drag the cursor to the required k C radius key Click each corner of a polygon and either double click to close the k X polygon or select Close Polygon from the con
263. ed by a user defined origin If a point is selected the selected shape s origin will default to the coordinates of the selected point Shapes may be defined using Lines Surfaces or Volumes The following shapes are supported cube cuboid cylinder and cone The origin of each shape 1s indicated by the axes 96 Chapter 4 Notes e Specifying a negative length or height results in that dimension being defined along the negative axis direction e For the cylindrical shape there is an option to create the cylinder with a seam which effectively creates a cylinder using only one surface rather than the default two surfaces Boolean Geometry Construction Boolean operations allow complex geometry to be defined by combining subtracting or intersecting existing Surfaces or Volumes LJ Union with simplify internal geometry enables a Surface or Volume to be defined by union of any number of selected Surfaces or Volumes LJ Union without simplify internal geometry enables a number of Surfaces or Volumes to be defined by union of any number of selected Surfaces or Volumes LJ Subtraction enables a Surface or Volume to be defined by subtracting one Surface or Volume from another Surface or Volume LJ Intersection enables a Surface or Volume to be defined as the intersection of two selected Surfaces or Volumes LI Slice Enables a selected Volume to be sliced by a plane and the resulting geometry to be deleted either side of
264. edom This is equivalent to applying a unit concentrated force at the selected nodal degree of freedom The value of the unit force depends on the chosen system of units 336 Chapter 8 In the case of SI units a force of 1 Newton or a moment of 1 Newton metre will be applied LI Point Displacement large mass method Sets the modal excitation to point displacement via a node number and a nodal freedom A force equal to the large mass is applied at the support point thereby inducing a unit acceleration response see note on large mass Displacement control is effected by integrating the response twice in the frequency domain Time domain displacement excitation is not currently supported LI Point Velocity large mass method Sets the modal excitation to point velocity via a node number and a nodal freedom A force equal to the large mass is applied at the support point thereby inducing a unit acceleration response see note on large mass Velocity control is effected by integrating the response once in the frequency domain Time domain velocity excitation is not currently supported LI Point Acceleration large mass method Sets the modal excitation to point acceleration via a node number and a nodal freedom A force equal to the large mass is applied at the support point thereby inducing a unit acceleration response see note on large mass Q Real Imaginary Real amp Imaginary Loading A load vector is extracted from specified e
265. edure used by LUSAS to predict the buckling load of a structure Also known as linear buckling eigenvector A deformed shape resulting from an eigenvalue analysis If a structure is excited at a resonant frequency then the shape that it adopts is the mode shape corresponding to the eigenvalue See also eigen mode mode shape elapsed time A measure of total time spent during an analysis or some other computer activity This time can be greater than the CPU time as it includes effects of other system activity such as disk access file transfer multiple users etc See also CPU time elasticity The property of a material to recover its original form on the removal of the loads elasto plastic Material behaviour that spans both linear and nonlinear regimes See also constitutive relationship element See finite element element normal A vector that is orthogonal to the face of an element Can be displayed graphically to check element face orientations element results Results at nodes within a finite element that are unaveraged with nodal results from surrounding elements See unaveraged nodal results 435 Modeller Reference Manual emissivity Ratio of the energy emitted by a real surface to the theoretical maximum possible at the same temperature Emissivity is always in the range 0 1 0 LUSAS assumes reflectivity 1 emmisivity end of file mark EOF A machine or machine equivalent that indicates that the l
266. eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeees 419 COS SAN ee cce cence ae A A AE conse nanesseavenceees E muecesednecco lt ctae vee 421 LL lt gt Gi PsP ne DEO SP CT SE EE ES De OEE OEE EAT Re Eee ey ese yer Pee eee 473 Chapter 1 Chapter 1 Introduction What is Finite Element Analysis Until the advent of computers the only way to find the answer to the engineering question What would happen if I did this to my new design was to build a prototype and carry out the necessary tests Today computers allow designs to be assessed much more quickly and easily Evaluating a complex engineering design by exact mathematical models however is not a simple process Since we cannot calculate the response of a complex shape to any external loading we must divide the complex shape up into lots of smaller simpler shapes These are the finite elements that give the method its name The shape of each finite element is defined by the coordinates of its nodes Adjoining elements with common nodes will interact Engineering Problem Finite Element Model The real engineering problem responds in an infinite number of ways to external forces The manner in which the Finite Element Model will react is given by the degrees of freedom which are expressed at the nodes For example a three dimensional solid element has three degrees of freedom at each node representing the three global directions in which it may move Since we can express the response of a s
267. eering drawing that you have worked from Check key drawing dimensions against co ordinates of respective points in the model Check the mesh for cracks and voids Checks for cracks must be made to ensure that the features form a continuous structure Check for correct material properties and assignments Check for consistent units Check for correct orientation of beam properties Check for correct boundary conditions loads supports Check element thickness against original model data plates shells Check reversed normals for plates shells 2 D Check element shapes for aspect ratio skew warp taper curvature and centrality of mid side nodes Warning messages will be present in the output file for all of the above From the LUSAS datafile dialog File gt LUSAS datafile menu item click on the Output button to check that the output provides sufficient checking information in the LUSAS Solver output file e g reactions It is often a good idea to carry out a pilot analysis on a crude model to check load paths and equilibrium In order to ensure that an adequate mesh density is used a mesh sensitivity study should be carried out It is good practice to keep an up to date log book with adequate plots including hidden line views to cover all parts of the model It is also useful to set up a reference system to select individual regions of the model using the groups facility Keep a log of analysis runs for future refer
268. eeviews use drag and drop functionality For example an attribute in the ob Treeview can be assigned to geometry by dragging the attribute onto the previously selected object Modeller Reference Manual JESAS Modeller spannar md daat ait Met eta REES lea A A A AAAA AEA A AAA D e m e s Px le le o el n ale Pl ie e Be hes a fp TO EEEE Lea eae eee la g E A pS ai fi D U A a 1 10 W _ D o ie maner md l a5 Aies 2h Mega a dk Toolbar buttons UR ed Aihe S Dp 3 4 Livisionsad tI Po SivkonanS ___ ieee Graphics Window E Diiisigh Tina E e e a kb adrape 1 T y Lamama Recut Tile 1 au r Esi Tmn aE Suie 3 i LU Theke amp 2 Thickrwee 15 A ETbickrasset0 a paca Sy Mates si ZE EE es E SHEJ hosie l Terki l Be THH Steel Ungraded fH me 1 seers Graphics Window Sy Suppers 11 diir Firme Ha Tfu Fired 2 HTH Iipr 2 anon i ara Camgrment GE Text Wind ow Max at wt Hoda 177 m Hi RITI E obtbede HF z Status Bar E z file O fesults soseabl d scross gt different gecHetrio property assignments arr 5 Sibel 2 reaulta iej Sd oS results file i Lis atteebled Acragas different qeceetric prsperty askicngen te it Hed pert FI e me a ons GAA SebcieiFeabeiaol LUSAS Modeller Interface Context Menu Although commands can be accessed fro
269. efined buttons using the scripting language Tree Frames By default a single Tree Frame is displayed with the Layers fo Groups kal Attributes ob Loadcases fc Utilities and Reports Treeviews visible Multiple Tree Frames can be utilised from the View gt Tree Frame menu item Treeviews can then be dragged and dropped between Tree Frames as required Browse Selection This window is not displayed by default but can be viewed using the View gt Browse Selection menu item Once visible it will contain a list of all currently selected items which may then be individually deselected 11 Modeller Reference Manual Browse Selection Memory This window is not displayed by default but can be viewed using the View gt Selection Memory gt Browse Memory Selection menu item Once visible it will contain a list of all items currently in Selection Memory which may then be individually deselected Browse Cyclable Items This window is not displayed by default but can be viewed using the View gt Browse Cyclable Items menu item Once visible it will contain a list of all cyclable items These may then be individually selected or deselected Note that once an object is selected other selectable items at the same position within the graphics window can be cycled using the Tab key or by reselecting with the left hand mouse button at the same position within the graphics window Data Tips Data tips also sometimes referred to as datatips prov
270. eismic isolator Joint Models LI Viscous dampers Kelvin and Four Parameter Solid modules available LL Lead Rubber Bearings with plastic yield and biaxial hysteric behaviour Q Friction Pendulum System with pressure and velocity dependent friction coefficient and biaxial hysteretic behaviour 187 Modeller Reference Manual Elasto Plastic Joint Models Smooth Contact tension F compression k strain hardening stiffness K elastic spring stiffness Yield force K lift off stiffness 02 61 Yield force g 62 61 w 02 01 K strain hardening piini K contact spring stiffness Frictional Contact 1 Frictional Contact 2 Fy or Fz i alata Fx Kcy or Kez contact spring stiffness yxy dy2 y1 or yYxz 6z2 z1 Exx 0x2 0x1 K contact spring stiffness 188 Chapter 6 Frictional Contact 3 Viscoelastic Damper Joint Model Fo k oe u coeff of me Ny e K friction ge 3 Lead Rubber Bearing Joint Friction Pendulum System Joint Force Force K post yield stiffness uN Displacement splacement K elastic spring stiffness Notes e Fora full description of the joint material input parameters required for these joint models please refer to the Solver Reference Manual e When defining joint properties for single joint elements the total stiffness or yield force should be defined When using
271. el Properties menu item Solution tab FibreSIM and Simulayt draping options can be specified at the xml file import stage accessed via the Attributes gt Composite menu item e The Volume xy axes control the local element axes which must lie in the plane of the composite lamina The local element axes may be visualised from the Mesh properties dialog The local coordinate defining the drape direction must lie in the xy plane of the drape Surface at the start point Defining Composite Layups Composite attributes require composite materials to be defined prior to defining composite layups Composite attributes consist of a number of named layers where each layer contains 243 Modeller Reference Manual specified material properties and for certain element types the angle of fibres and layer thickness Composite layers can be defined using a Normal or a Grid method Once composite attributes have been defined they are assigned to the model on a feature basis For Solids and Shells and Draped Solids and Shells composites definition the procedure described below can be used to define a layup For FiberSim Draped Solids and Shells definition the composite stack will already have been created using a default material and volume fraction for all laminae If required for this case the Normal and Grid Tabs can be used to modify details for selected laminae Procedure The procedure to define a composite layup using the Normal Tab is descr
272. elative option would not be applicable The example below shows one such example A i m N A i 3 i fs Py C i FP h aa F LA Cycle to Neighbours correctly aligns element axes of the selected elements with initially selected neighbouring element fo Y K LA S f a ie P Y l 4 4 Sf 4 A Cycle Relative only aligns element axes of the selected elements to best angle with respect to initially selected neighbouring element Q Cycle to Faces Mesh only models Solid elements may have their local z direction set from a selected Face Element axes are defined by the direction of the axes on the first Face in their definition This command reorders the Faces defining the Element such that the first Face in the definition is the selected Face The local x and y axes of the element itself may then be changed using the Cycle command 113 Modeller Reference Manual Notes e When cycling Surfaces it is not the Lines that change but the order of the Lines in the Surface definition Since the Surface local x axis lies along the first Line in the Surface definition the orientation of the Surface changes e When cycling Volumes the cycle command only changes the order of Surfaces in the Volume definition Since the Volume axes are determine by the orientation of the Lines defining the first Surface in the Volume the orientation of the Volume changes Case Study Changing Element Orientation When it is necessary for the local
273. eleted Defining Lamina Thicknesses The definition of lamina thickness depends upon the element types and model type used e The lamina thicknesses for shell models that have been assigned a geometric thickness are relative not absolute and represent the proportion of the total thickness as specified by geometric surface properties apportioned to each lamina 244 Chapter 6 e When assigning a draped layup to a shell model the assignment of geometric thickness properties to the shell is not always of use In these cases if a geometric property is not assigned to the model then the thickness of the assigned laminates is used to calculate the corresponding element and hence geometric thickness at any point So in this case the lamina thicknesses would be absolute values e The lamina thicknesses for solid models comprised of pentahedral and hexahedral composite elements are relative not absolute and represent the proportion of the total space that the elements of the volume represent apportioned to each lamina For these models the number of laminate layers must correspond to or exceed the number of elements through the Volume Element nodal positions will be moved to correspond with laminate boundary positions if the node laminate layer positions do not coincide e The lamina thicknesses for solid models comprised of tetrahedral composite elements are absolute values and represent the actual thickness of each lamina For these mod
274. els the total of all lamina thicknesses as measured from a tooling surface must exceed the space occupied by the tetrahedral elements e For a mesh only model a model that has been created by importing a LUSAS datafile the actual thickness of each lamina would be entered so in this case the lamina thickness is absolute Visualisation of Composite Layup The orientations and thicknesses for each lamina can be viewed by clicking on the Visualise button of the Composites dialog for a particular chosen entry method This will display a layered representation of the composite stack with annotations This representation may be used to create a bitmap annotation by clicking on the Create Annotation button Angles Materials g0 HH Material 1 D H Material Assigning Composite Properties The method of assigning composite properties to a model differs according to the type of composite definition method used 245 Modeller Reference Manual For the Solids and Shells definition method e The composite attribute created by this method is assigned to selected surfaces or volumes of a model by specifying the overall composite orientation Options for orientation are Local Coordinate Local Element Axes Axes From Surface An angle of zero degrees aligns the laminate axis with the x axis from the orientation axes For the Draped Solids and Shells definition method e For solid and shell models the composite attribute needs to be assigne
275. ely plotted for groups held in the Treeview by choosing the following Results Plots context menu items for each named group Plotting Results for Groups LJ Show Results LI Do Not Show Results LI Show Results Only On This Group Attribute When combined with group visibility options that can also be accessed via the context menu for each group name parts of the model can be isolated and have results plotted just for those regions Pairs of symbols adjacent to each group name in the L Treeview show the status of model visibility and results display When viewing results ai green tick All of the objects in this group are visible but no results are being shown i blue tick Some of the objects in this group are visible but no results are being shown pe red cross None of the objects in this group are visible and no results are being shown f green tick green border All of the objects in this group are visible and showing results 350 Chapter 8 fef blue tick blue border Some of the objects in this group are visible and some are showing results hf green tick blue border All of the objects in this group are visible but only some are showing results Notes e When choosing to show results for a material geometric property or element mesh type that does not support for example the same Contour entity as that used for the previously plotted item no results will be shown until a valid Entity and Component for the
276. em no results will be shown until a valid Entity and Component for the new attribute selection is picked on the Contours property dialog accessed via the Layers EE Treeview 351 Modeller Reference Manual Nonlinear Material Results Display Two types of nonlinear material results may be displayed Yield flags and crack crush patterns The availability of each depends on the material model assigned to the elements during the modelling stage Crack and crush patterns are available for concrete models and yield flags are available for all nonlinear materials L Yielded material Available from the Values layer specify the results entity as Stress and the type as Yield Yield flags show the extent of the yielded material within a structure and are plotted at Gauss points The nonlinear example here demonstrates how the spread of yielded material is visualised using a symbol at element Gauss points This display is especially useful when used in conjunction with contours or an animated sequence when the onset and spread of yield can be highlighted LJ Crack and Crush Patterns Crack and crush patterns can be displayed for models that use the Concrete material model Crack patterns are visualised using the Values layer by specifying the Results Entity as Stress and the Type as Crack Crush The patterns displayed show the extent of cracking crushing and the orientation of the cracked and crushed planes Crack pattern Crack
277. emaining model The element stresses and strains fluxes and gradients and other analogous quantities are all set to zero To model the addition of a part to the model an activate attribute is assigned In structural analyses an unmodified stiffness matrix is computed for the underlying elements and these activated elements are introduced in a stress strain free state except for any initial stresses or strains that have been defined Strains are incremented from the point of activation and the current geometry is used to define the activated element s initial geometry In a field analyses activation works in the same manner except that the quantities affected are the conductivity matrix or other analogous quantity the fluxes and the gradients By setting LUSAS Solver option 385 however loads applied to deactivated elements are preserved to enable reapplication if and when the elements are re activated Percent to Redistribute The deactivate command provides control over the way in which these internal forces are processed by specifying how much of the internal forces should be redistributed 223 Modeller Reference Manual Q Zero Redistribution 0 of the internal forces in a deactivated element may be redistributed in the system if this is prescribed in a static analysis and the load remains constant the stress displacements etc in the other elements will remain unchanged Q Full Redistribution 100 of the internal forces in
278. embers of a group visible or invisible w visible and for selecting and deslecting the members of a HS o et as Uniy Visible SToup PEET ET Limited results for a selected slideline group can be SS printed by using the Print Results menu item on the Peeled Henie context menu for that group Full slideline results for i Print Data the model as a whole can be printed using the Print Print Results Results Wizard Properties Printing Slideline Results The print results wizard is accessed from the Utilities menu When Slideline results are selected the following six types of results can be chosen for printing Q Summary LI System forces LI Gap Forces LI Contact forces LI Contact Stresses LI Section Results Each type of result is described below 361 Modeller Reference Manual Summary The summary presents a list of the maximum and minimum values of each slideline results in a table System Contact and Gap Forces There are three categories of force results System forces The normal and tangential gap forces at each slideline node are distributed across both slideline surfaces These forces are assembled together and transformed into the global system directions to give the System Forces Gap forces Gap forces are computed from the normal penetration and the tangential movement of a node They are the basic quantities used in the contact formulation For example with the penalty method the normal gap force a
279. ements in order to avoid a divergent solution Standard geometrically nonlinear formulations account for the change in position of the loading but not the change in direction relative to the deformed configuration Loading is always conservative for the Total Lagrangian geometrically nonlinear formulations that is the load is always applied in the same direction as was initially prescribed Using an Updated Lagrangian formulation the geometry is updated at the end of each increment and the applied loads may maintain the same relative orientation as to the original surface depending on element and load types Therefore non conservative loading can be increment size dependent True non conservative loading may only be achieved by using the Eulerian and co rotational formulations The choice of particular formulations is both problem and element dependent the element formulation determining which strain formulations are available The availability of each formulation is given for each element in the Element Reference Manual For further details regarding the geometrically nonlinear formulations refer to the Theory Manual 283 Modeller Reference Manual Nonlinear Boundary Conditions Deformation dependent boundary condition models account for the modifications to the external restraints resulting from support lift off or smooth or frictional contact within an analysis Within LUSAS node on node contact may be accounted for using joint elem
280. en choose Properties to display the feature properties Until a pen is set for an individual feature that feature will be drawn using the default pen LJ Normals Surfaces are coloured according to whether they are orientated showing the top or bottom of the surface Q Assignment Features are coloured according to which attribute is assigned to them Features with no attribute assigned are drawn in grey The picture below shows an example of this LI Group Features are coloured according to which group they are in Features not in a group are drawn in grey 72 Chapter 4 LI Type Each geometry type has a default pen associated with it This option causes all geometry to be drawn in that pen The colours may be set from the Model Properties By default the settings are red for Points magenta for Lines orange for Combined lines green for Surfaces blue for Volumes Q Line Surface Connectivity Features are drawn in colours according to the number of higher order features connected to them and areas of the model that have not been merged together correctly after import are highlighted by being drawn in a different colour One example of use is for checking models created from the import of 3D CAD data where the use of this option would enable any surfaces that were not correctly forming volumes to be seen Use of the merge facility would correct any unmerged and isolated features Mesh Key Surface Mesh 1 Divisions 1 Divisions 3
281. ence Note information such as element types numbers of loadcases frontwidth file sizes run times etc Keep regular backups of model When carrying out nonlinear or transient analysis it is always best to run a linear analysis first No time is really wasted as the model can easily be subsequently converted for the nonlinear or transient analysis afterwards 313 Modeller Reference Manual e Itis advisable to add in nonlinear behaviour in stages For example in a material and geometrically nonlinear run containing slidelines it would probably be advisable to start with only slidelines then add the geometric nonlinearity and finally add the nonlinear material effects In this way you can ensure that each nonlinear procedure is stable before progressing to the next Running an Analysis To create a LUSAS datafile and run an analysis either click on the Solve button or use the File gt LUSAS Datafile menu item Solver Licence Selection When running an analysis LUSAS Modeller passes all details of the licence it is running with to LUSAS Solver It includes the minimum set of licence options required to solve the job and a teaching and training identifier if Modeller is running in teaching and training mode To find a suitable Solver licence with which to run an analysis Solver does the following By default a Solver licence with the same licence key number or 25 character key as the Modeller licence is sought and if available
282. ence available to LUSAS Use the Modeller licence selection dialog to select a licence for use Use the Configuration Utility to add licences to the list of those available License order and usage Standalone or network licences are tumbled based upon Configuration Utility settings The order of the licence types listed on the Modeller licence selection dialog follows the order of the keys set on the Licensing page of the LUSAS Configuration Utility If the display of the main licencing dialog has been disabled the first licence in the list of those available will be used in preference to all others As licences are used the number of licences available for 13 Modeller Reference Manual others to use is updated accordingly When LUSAS Modeller is run the system will work its way down the list of licences until a valid and available licence is found Creating shortcuts The Create shortcut button provides the means to tie a licence type to a shortcut used to run Modeller or Solver and with the choice to Emulate LT or use Teaching and Training limits It enables LUSAS Modeller or LUSAS Solver to run without having to select a licence type each time unless that licence has already been used Example of shortcut created lt LUSAS Installation folder gt Programs lusas m exe LICNAM SENTINELLM TECHNICALO1 6274 6270 Licence details By selecting a licence and then selecting Licence details additional information such a
283. ents and arbitrary contact may be accounted for using slidelines Consider the simple example shown in the figure right in which the structure and its supporting surface can resist being pushed together but not being pulled apart The required contact condition may be imposed by using joint elements to connect between the structure and the rigid support and specifying a nonlinear contact joint model incorporating large and zero local stiffness in compression and tension respectively Rincian Distance x Materially Nonlinear Analysis Materially nonlinear effects arise from a nonlinear constitutive model that is progressively disproportionate stresses and strains Common examples of nonlinear material behaviour are the plastic yielding of metals the ductile fracture of granular composites such as concrete or time dependent behaviour such as creep LUSAS incorporates a variety of nonlinear constitutive models covering the behaviour of the more common engineering materials Details of these material models and their applicability to each LUSAS element are described in About Material Properties which should be read in conjunction with the Element Reference Manual Nonlinear Solution Procedures For nonlinear analysis since it is no longer possible to directly obtain a stress distribution which equilibrates a given set of external loads a solution procedure is usually adopted in which the total required load is applied in a in l
284. eory Manual 236 Chapter 6 The default value of the zonal contact detection parameter is 0 01 1 e 1 of the model size A smaller value may result in undetected inter penetration The value should be set to 1 0 if the contact search should consider the entire model though only points on the adjacent slideline surface will be considered valid contacts Q Slideline extension A boundary of a slideline segment can be expanded by specifying a Slideline extension Points outside the segment but within the extended boundary are considered valid for contact This is particularly useful near the edges of a slideline surface where a node could be on a segment in one nonlinear iteration and off the segment in the next iteration a form of chatter that can cause nonlinear convergence difficulties The extension parameter is an absolute number LI Close contact This defines a region above a slideline surface within which a soft spring is applied but with no force The stiffness of this spring 1s applied to all nodes that are above a surface but within the close contact region This softens the transition between in contact and out of contact states The close contact facility helps stabilise solutions suffering from chatter in which nodes oscillate between in contact and out of contact states Chatter can cause a nonlinear analysis to experience convergence difficulties The size of the close contact region is a factor of the segment size T
285. er to obtain an accurate load factor It should be noted that this procedure is not without its problems Depending 297 Modeller Reference Manual on the structure and the load level considered the eigenvalues can be very closely spaced causing convergence problems in the iterative solution e When specifying the range within which Eigen solutions will be located Sturm sequence checks are carried out on the range limits in order to determine the number of eigen solutions that exist within the range All solutions are then searched for unless a smaller number of solutions has been specifyed Eigenvalue Buckling Analysis A linear buckling analysis is a useful technique that can be applied to relatively stiff structures to estimate the maximum load that can be supported prior to structural instability or collapse The assumptions used in linear buckling analysis are that the stiffness matrix does not change prior to buckling and that the stress stiffness matrix is simply a multiple of its initial value Accordingly the technique can only be used to predict the load level at which a structure becomes unstable if the pre buckling displacements and their effects are negligible As this procedure involves assembly of the stress stiffness matrix only elements with a geometric nonlinear capability can be used in a linear buckling analysis The main objective of an eigenvalue buckling analysis is to obtain the critical buckling load which is achi
286. ered in the fatigue spectrum should sum to unity e For information on standard S N curves refer to BS5400 Fatigue loadcase Fatigue loadcases contain the loading spectrum defining the loading sequence in terms of a series of loadcases each of which has an associated load factor the number of cycles and the component to be used in the fatigue calculation Once defined fatigue loadcases are saved in the Se 0 3000 08 loadcase Treeview Their properties may be edited a s000E 08 0 70QDE 00 by double clicking on the fatigue loadcase A 14008 OF 0 130E 07 Fatigue Results Results from the fatigue calculations may be viewed using any of the standard methods once the loadcase is set active Fatigue results come from a component of stress which is specified in the Fatigue loadcase Two results are obtained from the calculations Q Loglife is the life expectancy of the structure based on the applied load Results are presented as logi0 of the number of cycles to failure LI Damage is a factor representing the damage the material has sustained due to the applied loading and number of cycles A value greater than 1 indicates failure 332 Chapter 8 Notes e Fatigue calculations are only applicable to linear elastic analyses and for continuum elements only e Fatigue loadcases may be saved in the model file or in a new model file when a results file only is opened Fourier Results Before the results
287. ered to be ruled surfaces Some surface operations will only work with ruled surfaces For example splitting intersecting filleting See also analytical surface regular surface irregular surface s n curve A curve used to express damage done to a structure for a given number of loading cycles Standard curves are available in BS5400 See also fatigue damage sampling point Sampling points are the locations along a tendon profile at which calculated equivalent tendon loads will be applied to the model See also Gauss point 459 Modeller Reference Manual screen annotation See annotation screen coordinates The coordinate system used to position annotations on the graphics area script file A name given to a collection of UNIX commands used to set up an environment and to run a program See also batch file parametric language command file search area The area over which a general point or patch load is applied may be limited using a search area secondary creep Commonly used linear region of the creep curve second moment of area The second moment of area of a plane area with respect to the x axis is defined by the integral of x squared over the area Also known as moment of inertia of area See also first moment of area polar second moment of area product moment of area section line A section along a line from which results can be taken and placed in graph datasets See also graph dataset section slice
288. erged with merge status set to ignore assignments and the assignments are indeed different the remaining feature will inherit the assignment of the lowest numbered deleted feature e Iftwo coincident features are not merged two sets of coincident nodes will be generated when they are meshed and the finite element mesh will be unconnected at the feature discontinuity This may be corrected at the meshing stage by merging the nodes using the equivalence facility 104 Chapter 4 Using the Merge and Unmerge Commands LI Merge Point Coordinates of Points to be merged must lie within the merge tolerance By default assignments must be exactly the same for a Point to be merged Merge Tolerance Pl LDG1 SUP1 EQV1 P3 LDG1 SUP1 EQV1 Q Merge Line Lower order features must be L1 MSH1 MAT1 GEOM 1 common for merging to take place By default L2 MSH1 MAT1 GEOM1 assignments must be exactly the same for a Line to be merged P1 L1 L2 P2 m LI Merge Surface Lower order features must be Sl MSH1 MAT1 GEOM1 common for merging to take place By default S2 MSHI MAT1 GEOML assignments must be exactly the same for a Surface to be merged 105 Modeller Reference Manual Merge Case Study 1 Merging Lines with different non zero assignments Wild and Ignore Assignments will merge Lines successfully Line 1 P2 L1 MAT1 p1 MSH1 Merge Characteristics After Merging No mer
289. es are computed using engineering beam theory which assumes that the normal stress is constant across the width of the beam cross section This assumption can introduces significant errors due to shear lag when wide flanged sections are being used so these stresses should be used with caution Beam stresses can be displayed as contours on the fleshed section or as values diagrams or beam contours at fibre locations using the standard layer controls When viewing stresses at fibre locations the value diagram or contour is drawn at the actual position of the fibre on the cross section Examples follow 355 Modeller Reference Manual Loadcase 1 Loadcase 1 Results file tubular rooft_frame mys Entity Stress Thick 30 Beam Component Sifs wiy hizi 7 12163 E 5 54122 E 3 56081 EG 1 72041 EG 0 465661 E 9 1 75041 EG 3 56081 EG 5 344122E6 T 12163E Masimum 7 97 335E6 at point 1 of element 11 Minimum 2 05031EG at point 1 of element 9 Filled contours plotted on fleshed beam sections Loadease 1 Loadcase 1 Results file tubularroof_frame mys Entity Stress Thick 30 Beam Component SxfFx hiy hz 7 12163 EG 5 34122 E 3 5603 1 EG 1 75041 EG 0 45565 1 E 9 1 780441 EG 3 56031 E6 5 34122 EG 7 12163 EG Maximum 7 27 S35E6 at point 1 of element 11 Minimum 8 05031E6 at point 1 of elementd Z Line contours plotted on fleshed beam sections 356
290. ese features In the Assign Slideline dialog that appears specify Slave and the set of features to which it applies The orientation is computed automatically but needs to be specified for shells Top or Bottom Slideline Modelling Considerations Except for tied slidelines the slideline contact facility is inherently nonlinear and must be used in a nonlinear analysis Only the expected region of contact should be defined as a slideline surface for tied slideline analyses Coarse mesh discretisation in the region of contact should be avoided Slidelines must be continuous and should not subtend an angle greater than 90 degrees Sharp corners are best described by two separate slidelines Large mesh bias should be avoided when using quadratic patches to ensure a reasonable curved geometry is generated The stiffness scale factors should be increased for rigid wall contact The nodal constraint slideline explicit tied slideline treatment is more robust if the mesh with the greatest contact node density is designated the slave surface The use of tied slidelines to eliminate transition meshes is recommended for areas removed from the point of interest in the structure The use of a larger value for Young s modulus to simulate a rigid surface in a dynamic contact analysis is not advisable since this will increase the wave speed in that part of the model and give rise to a reduced time step This practice significantly increases the computing time
291. esponse The crushable foam material model accounts for both of these responses The model defines the volumetric behaviour of the material by means of a piece wise linear curve of pressure versus the logarithm of relative volume An example of such a curve is shown in the diagram below where relative volume is denoted by V VO pressure Compression K Bulk modulus K Bulk modulus In V VO Tension cut off pressure eee ee ewww een eeneee Pressure Logarithm of Relative Volume Curve From this figure it can also be seen that the material model permits two different unloading characteristics volumetrically LJ Unloading may be in a nonlinear elastic manner in which loading and unloading take place along the same nonlinear curve Q Volumetric crushing may be included by clicking in the volumetric crushing check box in which case unloading takes place along a straight line defined by the unloading tensile bulk modulus K which is in general different from the initial compressive bulk modulus defined by the initial slope of the curve In both cases however there is a maximum or cut off tensile stress cut off pressure that is employed to limit the amount of stress the material may sustain in tension The deviatoric behaviour of the material is assumed to be elastic perfectly plastic The plasticity is governed by a yield criterion that is dependent upon the volumetric pressure compared with the classical von Mises
292. esults at different nodes a graph will be plotted of the stress throughout an analysis at three nodes say 6 25 and 60 Using a suitable results file first select the nodes with the cursor then L 2 3 10 11 12 Start the Graph Wizard from the Utilities menu Choose Time History click Next For the X axis choose Named variable click Next choose Response Time click Next For the Y axis choose Nodal click Next specify the results entity as Stress specify node number 6 click Next Either type suitable graph and axes titles or leave them blank to use default names click Finish The graph is displayed Repeat steps 1 and 2 For the X axis choose Named variable click Next but this time choose Previously defined click Next Select Response Time from the drop down list click Next For the Y axis choose Nodal click Next specify the results entity as Stress specify node number 25 click Next Choose Add to existing graph make sure to specify the correct graph from the list if there is more than one click Finish The new data will be added to the first graph Repeat steps 1 2 and 7 For the Y axis choose Nodal click Next specify the results entity as Stress specify node number 60 click Next Repeat step 9 Creating Animation Sequences Animations are useful for checking a staged construction modelling process has been defined correctly or for visualising the changing results of a nonlinear dyn
293. esults file Lee atte led across diffaranti 4eceetric pseperky atkicnaents tot Hid ie FI Ure Mri eE bzo MSTS GWA Sakse Face keda 0 1 Attribute manipulation Attributes are manipulated using the context menu in the ob Treeview accessed by clicking the right mouse button on the attribute with the following commands LI Copy Enables the attribute to be copied and assigned to a selected group or window using paste Q Rename Attributes can be given meaningful names for example Steel to describe a material or Beam Four Divisions to describe a Line mesh LI Delete Existing attributes may be deleted LI Edit Attribute Allows the properties of the attribute to be modified If a new name is given a new attribute is created and the original attribute is left unchanged Q Visible Makes visible all features to which the selected attribute is assigned Q Invisible Makes invisible all features to which the selected attribute is assigned LI Set As Only Visible Sets the whole model invisible and then makes visible only those features to which the selected attribute is assigned 117 Modeller Reference Manual Q Advanced Visibility Provides fine control over the visibility of features to which the selected attribute is assigned LI Results Plots permits results for selected attributes to be selectively plotted LI Select Assignments Selects the features that have the selected attribute assignment LI Deselect Assignme
294. et Default In the Graphics Area right click and select Properties 6 Deselect Use Windows colours select a Black background colour choose a Yellow selection pen and click OK when done 7 Select File gt Script gt Stop Recording 8 Exit from LUSAS m 44 Chapter 2 Toolbars and Toolbar buttons The toolbars used on the Modeller user interface can be adjusted by using the View gt Toolbars menu item Toolbar groups can be turned on or off new toolbar groups can be defined customised toolbar groups can be created and user defined toolbar buttons can added to the user interface either to sit on a new toolbar group or to sit alongside existing buttons in an existing group Toolbar manipulation is provided by a third party and incorporated into LUSAS Modeller for general use Turning toolbar groups on and off Toolbar groups are listed in the Toolbars dialog and may be turned on or off by checking each item in the list The following options are also available LI Show Tooltips shows a temporary description of the toolbar button when the cursor is moved over the button LI Cool Look removes the raised button style to leave a flat button Q Large Buttons are not implemented in LUSAS modeller Creating a new toolbar group Favourite toolbar buttons and any user defined toolbar buttons can be grouped together into a new toolbar group e Use the New button on the Toolbars dialog to create a new named toolbar group suc
295. ethod is used which incorporates Modular Ratio techniques Slice options Additional options are available for the control of the slicing These include LI Effective width If the effective width option is selected the width of visible elements to include in the calculations can be specified This effective width is centred on the slicing path in the screen plane at a perpendicular to the path If the effective width is not used all valid visible elements will be included in this direction For both options the slice is infinitely deep in the slice local y axis 359 Modeller Reference Manual LI Include whole elements only If the effective width option is selected the option to include whole elements only is available If selected partial elements intersected by the current slice will be ignored in the calculations LI Smooth corners on path If the smooth corners on path option is selected the average tangent of the path at a connection between two lines arcs will be used for the slicing if the distance along the slice path exactly matches this path connection If the smooth corners on path option is not selected two slices will be taken at the connection using the tangents for both of the lines arcs connecting at this location Q Slicename prefix Allows user to input a user defined prefix for the slice names Loadcase Slice resultant results can be output for one or more loadcases Q Active prints slice results for the active loa
296. etric property effective width has to be defined 330 Chapter 8 for the grillage to compute these equivalent moments The effective width is defined in the grillage geometric attribute Wood Armer properties are specified on the Wood Armer dialog which is activated when a Wood Armer component is selected from the contour values or vector layer properties or from the print results wizard The properties specified in the Wood Armer dialog are applicable to all layers Wood Armer Assessment The Wood Armer calculation is generally based on a rationalised set of equations intended to enable efficient design However it is sometimes necessary to consider arrangements of reinforcement which have design strengths based on a different rationale A typical application is the assessment of an existing structure If the capacity of the section in the direction of the reinforcement is known the utilisation factor based on optimal use of the available capacity can be computed A utilisation factor greater than 1 signifies the slab is under reinforced and extra reinforcement is required Alternatively the Wood Armer K factor may be entered to proportion the applied twisting moment between the reinforcement directions This allows any spare capacity that exists in either direction to be utilised Notes e Grillage Wood Armer results are only valid for small skew angles e When calculating Wood Armer results the x direction may be
297. eved by solving the associated eigenvalue problem For buckling analyses involving constraint equations the Fast Lanczos solver will only find eigenvalues either side of zero 1 e in the range 90 0 or 0 If a range of eigenvalues is required in an interval which contains zero two separate analyses must be carried out where the interval is divided into two sub intervals either side of zero Alternative Eigenvalue Buckling Occasionally the initial stress stiffness matrix may not be positive definite causing the eigensolution method to fail To overcome this problem the original buckling problem may be recast into a form where all eigenvalues are positive except when the buckling load factor is less than unity When using this technique the load level must be adjusted to ensure that all the load factors are greater than unity In other words the load applied should be below the lowest expected buckling mode of the structure An accurate load factor will however only be obtained if the specified load is close to the collapse load It should be noted that this procedure is not without its problems Depending on the structure and the load level considered the eigenvalues can be very closely spaced causing convergence problems in the iterative solution Output From Buckling Analyses For a linear eigenvalue buckling analysis the buckling load is obtained from the print results wizard This buckling load is directly related to the eige
298. eveuswcdudeascuanssensiewdcencuaedecestaucases 54 Picture FINGS sesecsicectecacscsstcaceenseaniensscanseeuesaninntetcsscwaseantaweeccesimsteas iwastanscesseastiweieansimsawertimeetanees 54 NUR PS sss oes sac attic nce EE E E E A T E 55 interlace NGS ossis ae cacaneqetcepeuecceaneeezsaeecncecasqeascassteecuasttestecavieweeenice 56 agea p a E E E E E E 57 Iimporing M sh Dala ssrin A EEA e EAEE 59 Exporting Model Data iinnirn EnEn REAA EARE ANAA RERE SERENADEN AAR 59 DXF interlace Filo S roccscst carps stew e e E OEE EN a 60 IGES IMPDO EKOTI s iirensairEnnnse nsaan EAA AEAEE EARNER 62 NASTRAN BDF and DAT IMpott aaaaaaaaaaaaaennannnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nnmnnn 66 ABAQUS Input File Imporl iriiria siaa naa ira Anaa saig 66 ANSYS CDB File IMDpON renunsia a a E Ri 66 PATRAN interface Files sassis inania i aE aE a 66 SOIVEF DAT IMPON iaria Ea ET aae raa aE 67 STEP import EXPO isi a Eaa E aE aAA aaa 67 STE MPO EXPO searre AEE AEN EAA EEA NAE AAEE OAAR 68 Chapter 4 Model Geometry sssssssssnssnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nnmnnn nnmnnn nnmnnn nnna 69 igiigerol ile itel n PEO m nnee EAE E E A A E E E 69 Vis alising GEOMEULY ccr NAAS AREE REE 70 eUD S A E T E E E 75 B E E E A E E E E E E E E AT 76 CombDined LINGS siiis aara ET TENNE EOE NNE 82 Modeller Reference Manual Surfaces se ice a a ae aaa RO at ale 85 VOUM S loa tectees ave ear a EA eee aed A aa can aaa soma wi cua youu aaa
299. eview select the report name containing data to be exported and use its context menu to select View Report 4 After the report is displayed in the report viewer find the Results Chapter containing data to be exported and double click in the body of the data to create a sub report 5 Ifresults for a particular loadcase is to be exported double click on that loadcase data to create a further sub report 6 Lastly use the Export Report button tF to allow selection of the Format and Destination of the results data to be created Example output The images that follow show an example of a report created by LUSAS and the same data exported to an Microsoft Word document Psaeisseel vm soar 3 s F E teste 4 ide aee he i be so see ide co be iee aee ise e see s pe oats po ga Ko A Gr m ig gt EFE EEFE eo ae s e Report listing in the report viewer Report data exported to a Microsoft Word document Printing Report Data When viewing a report report data may be printed by selecting the Print Report button in the BusinessObjects Crystal Reports toolbar Deleting Report Data M Es To delete the visible report or sub report select the Close Current View button at the top right of the report viewer toolbar 388 Appendix A Appendix A Smart Combination Examples Smart Combination Examples The following examples demonstrate how the different factors and settings can be used in s
300. f epee PEN 1 f a eS ae j 1 fY a j s IN PAYDAY SN ALES X AH OX KO oT HA j gt j IN F AN 5 7 j l N n EA Pa J th dl f j PR NGO kt j D Th i i j A H lt AN Sok bad f St x i K CATT AY LAN KILIY at tet YA A Y wT Ty t y Fk LA E a TY ee Hr 4 x a A f Cry LAS a A J t a Xx j i Ef J IN ff 1 Wa f 1 y 4 A Y gt X f i N f n 5 i 1 i j 4 yf i f Gos f qi Y 2 a ih org UEN rarai A TAYAY PE TEN a r a ee uR O a F t AY YHN MALU Y XR A r am nee ha i riction i i 1 j f i i t f i f j i z a ss i CEE dl JX Lt eae Fiat ard slideline Tied slideline Slidelines are assigned to pairs or groups of features in a model with one pair group termed master and the second pair group termed slave An element face that lies on a slideline is called a slideline segment When one slideline surface is much stiffer than the other it can be defined as a rigid slideline surface This approximation can improve the convergence rate and hence reduce the solution time If the rigid surface is not part of the model rigid elements should be assigned to the features Note Except for tied slidelines the slideline contact facility is inherently nonlinear and must be used in a nonlinear analysis Table of Elements for use with Slidelines The following table gives a list of elements valid for use with slideline
301. f practice The slice resultants are computed using valid visible 3D beam and shell elements Invisible elements are ignored Slice locations The slice locations are defined using a path which can consist of straight lines and arcs or combined lines that contain straight lines and arcs in the selection The path must be continuous without any branching characteristics The slice path orientation is defined by either the order of selection when more than one line arc is selected or the orientation of the 358 Chapter 8 line arc if only a single line arc has been selected The locations for the slices along the path can be defined using three methods LI From points or nodes in the selection If nodes or points are selected these are projected onto the path perpendicular to the appropriate path segment tangent to obtain the slicing locations LI Incremental distances from start of path Incremental distances can be entered to define the distances along the path for the slicing Distances can be both positive and negative but the running total distance should remain within the length of the path For example 1 0 1 10 1 5 will cut slices at distances of 0 10 and 5 along the path LI Absolute distances from start of path Absolute distances can be entered to define the distances along the path for the slicing Distances must be positive and within the length of the path For example 0 5 10 will cut slices at distances of 0 5 and 10 along the
302. f the material response This enables the viscoelastic material behaviour to be represented by a shear modulus Gv and a decay constant B Viscoelasticity imposed in this way acts like a spring damper in parallel with the elastic plastic damage and creep response Coupling of the viscoelastic and the existing nonlinear material behaviour enables hysteresis effects to be modelled User Supplied Visco Elastic Properties The user supplied viscoelastic properties facility enables routines for implementing a user supplied viscoelastic model to be invoked This facility provides completely general access to the LUSAS Solver property data input via this data section and provides controlled access to the pre and post solution constitutive processing and nonlinear state variable output via these user supplied routines Notes e When viscoelastic properties are coupled with a nonlinear material model it is assumed that the resulting viscoelastic stresses play no part in causing the material to yield and no part in any damage or creep calculations Consequently the viscoelastic stresses are stored separately and deducted from the total stress vector at each iteration prior to any plasticity creep or damage computations Note that this applies to both implicit and explicit integration of the creep equations e Nonlinear Control must always be specified when viscoelastic properties are assigned In addition Dynamic or Viscous Control must also be specified
303. ffective heat capacity including the effects of the latent heat of evolution due to phase changes and is the temperature In the material data input both H and C may be specified For analyses where phase changes are not represented the effective heat capacity value C is used in the calculations For analyses where phase changes are represented tabular input should be used to define the variation of H with temperature together with an initial value of C Providing a variation in temperature exists at a point the effective specific heat is then interpolated from the enthalpy values If no variation exists for example in an area of the problem that has experienced no change in temperature from the initial temperature then the initial value of C is used 306 Chapter 7 For nonlinear analysis the nonlinear control parameters are used to define the iterative strategy The convergence section is utilised to provide tolerances for defining steady state and either a field norm temperature equivalent to the displacement norm or a residual flow norm equivalent to the residual force norm may be used Fourier Analysis Fourier elements offer an efficient method to solve problems in which axisymmetric structures are subjected to non axisymmetric loading provided that the displacements are small and linear theory applies The circumferential displacements and variations of load are expressed as the sum of the components of a Fourier series whilst
304. ffects 115 Modeller Reference Manual LI Retained Freedom specifies the master nodes used in a Guyan reduction or superelement analysis Q Damping defines the damping properties for use in dynamic analyses Q Birth and Death allows elements to be added birth and removed death throughout an analysis e g in a tunnelling process or a staged construction LI Equivalence allows nodes which are close to each other but on different features to be merged into one according to defined tolerances LI Influence parameters define the type of behaviour of the structure at and around an influence point LI Age defines the time between creation and activation of features in the model Q Search Area restricts discrete point and patch loads to only apply over certain areas of the model LI Crack tip define a crack tip attribute to allow a crack tip location to be defined at a point or line in a model LI Design strength define strength data for use in conjunction with Design Factor Plots Manipulating Attributes Attributes are defined from the Attributes menu Defined attributes are shown in the b Treeview and can be assigned to selected geometry features or to mesh objects in a mesh only model by dragging and dropping them onto the model or assigning them from their context menu Attribute symbols explained A symbol adjacent to each attribute name in the b Treeview shows the status of each attribute present b A coloured
305. fied as non zero if desired LI By Points Defines a Surface from three or more selected Points A Surface can be defined from any number of Points LI By Lines Defines a Surface from the selected Lines When defining Surfaces in this way any number of Lines may be specified in any order and a Surface will be formed from the greatest number of lines that form a closed loop If a number of disconnected Lines are selected a Lofted Surface will be created A lofted Surface is defined as Surface with a smooth transition between 2 or more Lines 4 3 9 N 4 1 cone Surfaces generated from selected Lines Q cylinder 85 Modeller Reference Manual ity Lofted Surface generated from selected Lines Note The direction in which the Surface is defined is used to define the Surface orientation The surface orientation is used at a later stage to define element normals and local loading directions Coalescing Surfaces Two or more surfaces can be reduced to one surface defined by lines or combined lines if the surfaces share a common line Holes in Surfaces LI Create Defines a hole or number or holes in a Surface Closed loop s of Lines or the Surface s representing the hole s and the Surface to be holed should be selected prior to choosing this menu option LJ Move Moves or modifies selected hole s within a Surface To move a hole select the Lines and or Points forming the perimeter of the hole If onl
306. flex plate modal damping Damping associated with the displacements defined by the eigenvectors Its value has no physical significance since the eigenvector contains an arbitrary normalising factor modal domain The solution of a dynamics problem by utilising the system eigenvectors modal synthesis A sub structuring or superelement technique involving multiple Guyan reductions for very large natural frequency analyses mode shape The displaced shape of a structure due to its natural frequency See also eigenvector eigen mode eigenvalue analysis 449 Modeller Reference Manual model file The LUSAS database is stored in a binary file called a model file modified Newton Raphson Modifications to the standard Newton Raphson nonlinear solution method whereby the stiffness matrix is updated less frequently common forms are referred to as KT1 KT2 Ko More iterations are generally required but the method can be computationally economical See also Newton Raphson modem An acronym for modulator demodulator A modem converts data from a computer to analogue signals that can be transmitted down a telephone line It also converts signals from a telephone line into a form the computer can use modulus matrix A matrix of material constants that relates stress to strain See a so rigidity matrix move To alter the position of a feature using a transformation dataset See also copy transformation dataset MS DOS Ac
307. for the Fourier can be established it is necessary to define a combination in which the Fourier harmonics are combined to provide an overall result The combination is created using Utilities gt Load Combination gt Basic menu item Once the combination has been generated for all the harmonics required and the analysis run to create a results file the combination loadcase should be set active There are then two ways to view results from a Fourier analysis Q By manually specifying the angle around the circumference at which the results are required and using contours values and vectors to view the results at that position in the model LI By using the graph wizard to display the variation of results around the circumference for a specified node Design Factors Design factors provide a means of assessing the reserve strength capacity of a component or structure To use this facility the results file must be loaded on top of the model file The material strength and design factor are defined from the Attributes gt Design Strength menu item and assigned to the model The reserve strength can then be visualised over the entire model using the Utilities gt Design Factors menu item The following criteria are available Q Maximum Stress Theory Rankine Q Maximum Shear Theory Coulomb Tresca Q Maximum Strain Energy Theory Beltrami Q Maximum Distortion Energy Theory Huber von Mises Hencky LJ Maximum Strain Theory St Venant Resu
308. formation about the model such as its EYE COORD 0000 EYE COURD 1000 view scale and orientation and if a results file is loaded a summary of key values for a particular loadcase LJ Window summary position The location of the summary block of text with reference to the left right bottom or top of paper Note that the Window summary can be moved easier graphically by selecting it and then dragging it to a new position Notes e Ifthe annotation is eclipsed by other model data drag the layer in the Treeview to the bottom of the stack so that it is drawn last e An annotation toolbar is available but by default is hidden It can be displayed from the View gt Toolbar menu item From this toolbar coordinate positioned text and bitmaps can be defined and cursor positioned lines boxes polygons and arrows added Editing Annotation After being added to a model window both cursor positioned and coordinate position annotation can be easily moved by selecting it with the cursor and dragging to a new position In addition all defining parameters such as location style and in some cases content can be edited 41 Modeller Reference Manual To modify the properties of a piece of annotation select the annotation right click then choose Properties from the context menu The following properties apply to most annotation types Q Anchor point Annotation can be located with respect to the model model coordinates or to the
309. formation displayed in rapid succession to give the impression of movement anisotropic Material allowing different material properties to be specified in arbitrary non orthotropic directions by direct specification of the modulus matrix See a so orthotropic annotation Information added to the screen to clarify a plot This may take the form of text lines symbols results summaries etc application A computer program designed to meet specific user needs This term is interchangeable with program apply See apply button apply button This push button will carry out the actions signified by the chosen form subject to the parameters entered then re display the form allowing you to enter further data arc length method A generalised form of displacement control where the load level does not remain constant during each load increment so that convergence near limit points may be achieved A benefit of the arc length method is that it can stabilise the iterative process See also constant load level line search Also known as arc length control arrow keys On your computer keyboard the keys you use to navigate around your screen Each key is marked with an arrow and is named for the direction in which the arrow points There is an UP ARROW DOWN ARROW LEFT ARROW and RIGHT ARROW key Also known as direction keys or cursor keys ASCII Acronym for American Standard Code for Information Interchange ASCII is a standardised 8 bit c
310. g Short edge removed EiS i i Mesh before edge collapsing Mesh after edge collapsing 128 Chapter 6 Elements with small subtended angles removed Controlling the Mesh Density The simplest way to define the mesh density is to define the number of divisions to be used in the mesh attribute This method should only be used for simple models because changing the mesh density when multiple mesh attributes have been defined is both time consuming and prone to error For most model the mesh density should be controlled using boundary discretisation Boundary Discretisation In the case of Surface or Volume meshing the number of mesh divisions may either be specified directly in the Surface or Volume mesh attribute or using Line or Surface mesh attributes of element type None In many realistic problems where several Surfaces or Volumes exist using attributes with an elements of type None is the most convenient way to define the mesh density For Lines the spacing is specified using either element length or number of divisions and for Surfaces the mesh size is specified as the element edge length Notes e Ifthe element size is specified differently in the Line and Surface mesh attribute the Line element size will be used e Ifthe element size has not been specified the default number of mesh divisions will be used LJ Regular Surface Meshing The applied boundary discretisation left produces the irregula
311. g should be applied to any loadcases following the one that contained the load 22 Chapter 2 assignments If done so the initial applied loading for those loadcases will be lost LI Integration options e Fine integration for stiffness and mass Invokes a finer numerical integration rule for elements LUSAS Solver option 18 e Fine integration for mass HX16 and HX20 Formulate mass matrix with fine integration LUSAS Solver option 91 e Coarse integration for semi loof shells Invokes coarse numerical integration rule for semiloof elements This option under integrates the semi loof shell element which may have the effect of removing low energy mechanisms when the element is very thin and or pressure loaded LUSAS Solver option 19 e Newton Cotes Integration for beam elements Newton Cotes is a form of numerical integration or quadrature It is often used for through thickness integrals since sampling points are located at the extremes of the range LUSAS Solver option 134 LI Nonlinear Options e These options define the type of geometric nonlinearity to be used in the analysis The default is for no geometric nonlinearity See Geometric Nonlinearity Consult the Element Reference Manual to check which geometric nonlinearity type is supported for selected elements Geometric nonlinearity e Total Lagrangian A strain formulation that has its reference as the initial configuration at the start of the analysis LUSAS Solver op
312. g the assigned mesh attributes If Mesh Lock 1s on this will not occur LL Mesh Now meshes the whole model regardless of any Mesh Lock being set LI Mesh Selected Items meshes only those features selected LI Use Deformations uses the deformed mesh caused by one analysis to be used as the starting point for a further analysis The mesh may be tabulated with node coordinates computed from the deformations in the active loadcase multiplied by a specified factor To do so a model file and its results file must be loaded with the required results loadcase set active Joint and Interface Elements Q Joint elements are used to connect two or more nodes with springs having translational and rotational stiffness They may have initial gaps contact properties an associated mass and damping and other nonlinear behaviour LI Interface elements are used for modelling interface delamination in composite materials Both joint and interface elements may be inserted between pairs of corresponding nodes and features Defining and Assigning Joints A Joint element is defined as a Point Line or Surface mesh attribute using the Attributes gt Mesh menu and specifying the structural element type to be used Once defined it is assigned to the model in one of two ways LI To a single pair of features This requires two points or lines or surfaces to be selected The first selected feature becomes the master The second selected feature becomes the
313. g time usually expressed in seconds See also elapsed time CQC method A method used in spectral response analysis which gives a combination formula that includes all cross modal terms Stands for complete quadratic combination See also SRSS method seismic analysis crack tip elements A non standard continuum element family in which the mid side nodes on 2 of the element edges are moved to the quarter point This enables an accurate resolution of stresses to be obtained at a sharp notch or crack cracking Material nonlinearity resulting from material failure Most directly associated with the concrete ductile fracture material model in LUSAS creep The time dependent inelastic deformation of a material which causes a permanent change in the material once the loading is removed Creep can occur as soon as the body is stressed and is independent of a yield criterion 429 Modeller Reference Manual critical damping The damping value for which the impulse response is just oscillatory critical point Either a limit point or a bifurcation point critical time step The time step in an explicit dynamic analysis that satisfies the conditional stability criteria critically damped system The dividing line between under damped and over damped systems where the equation of motion has a damping value that is equal to the critical damping current group The group which will contain all newly defined geometry features current
314. ggregate size Thus p is not in a fixed ratio to 174 Chapter 6 e A plane of degradation POD is formed when the principal stress reaches the fracture stress f the POD is formed normal to the major principal axis Thereafter it is assumed that damage on the plane can occur with both shear and normal strains Damage surface Local Damage Surface The constants r and u are the strain equivalents of the material input parameters ro and u The relative shear stress intercept to tensile strength ratio r J c f where c is the shear stress intercept e Fine integration and the non symmetric solver are always set by default with this material model e tis recommended that the following LUSAS options are used with this model 252 Suppress pivot warnings 62 Allow negative pivots See the Solver Reference Manual and Theory Manual for further details 175 Modeller Reference Manual Stress Resultant Model 29 Creep The model is formulated directly with the beam or shell stress resultants plus geometric properties therefore it is computationally cheaper Consult the Element Reference Manual the check which elements are valid for this material model Material Parameters L Yield stress The level of stress at which a material is said to start unrecoverable or plastic behaviour LI Section shape Match the section type to the element being used See the Solver Reference Manual for further
315. ging takes place _ No merging takes place Merged and attributes transferred Merged and attributes transferred 106 Chapter 4 Merge Case Study 2 Merging Lines with additional material assignment on Line 2 Material assignments differ therefore only Ignore assignments will merge successfully After Merging No merging takes place No merging takes place No merging takes place Merged and attributes transferred Using the Unmerge Commands To unmerge a feature from a higher order feature 1 e a point from a line select both the feature to be unmerged and the higher order feature from which to unmerge it In the following examples red represents New and green Modified geometry 107 Modeller Reference Manual L Unmerge Point in LineUnmerge Point 2 in Line 2 A new Point 4 is copied from Point 2 and Line 2 is redefined using Point 4 Points 2 and 4 are coincident Point 4 is unmergable LJ Unmerge Point in SurfaceUnmerge Point 5 in Surface 2 A new Point 8 is copied from Point 5 a new Line 9 is defined and Line 6 is redefined using Point 8 New features are set to be unmergable Point 5 and Point 8 are coincident 108 L Unmerge Point in VolumeUnmerge Point 1 in Volume 1 A new Point 2 new Lines and a new Surface are defined and affected Surfaces and the Volume are redefined The new Point is coincident with Point 1 LJ Unmerge Line in SurfaceUnmerge Line 5 in Surface
316. gnitude of the diagonal terms This could be caused by large stiff elements being connected to small less stiff elements or elements with highly disparate values of stiffness e g a beam may have a bending stiffness that is orders of magnitude less than it s axial stiffness A negative pivot in a non linear analysis usually means that a limit or bifurcation point has been encountered However negative pivots sometimes occur during the iterative solution which sometimes means that the load step is too big but disappear when the solution has converged If negative pivots occur and the solution will not converge then first try reducing the load step If the solution still does not converge a limit or bifurcation point may have been encountered in which case the solution procedure may need to be changed Running the problem under arc length control gives the best chance of negotiating a limit or bifurcation point A load limit point can also be overcome by using prescribed displacement loading Check the LUSAS Solver output file for other warning or error messages Check adequate mesh density Check average nodal stress calculations are not carried out across discontinuities S p oS eS Check the model summary information available in the LUSAS Solver output file This gives the total length area volume and mass for the structure together with the centre of gravity moments of inertia and resultant applied load at the origin Dynamic Analy
317. gs See the appendix on element restrictions in the Element Reference Manual for more information Notes On Orthotropic Material Properties For orthotropic material models the D matrix must be symmetric and a number of further relations must also be satisfied Material properties orthotropic e g QPM4 To maintain symmetry nyx nxy Ey Ex and to obtain a valid material nxy lt Ex Ey 1 2 This applies to Fourier elements as a special case to simulate a bladed structure Material properties orthotropic plane strain e g QPN4 Ey nxy Ez nyz nxz Ex Ex nxy Ez nxz nyz Ey 404 Appendix B Material properties orthotropic axisymmetric e g QA X4 To maintain symmetry nyx nxy Ey Ex nzx nzx Ez Ex nzy nyz Ez Ey and to obtain a valid material nxy lt Ex Ey nxz lt Ex Ez 2 nyz lt Ey Ez 2 Material properties orthotropic solid e g HX8 QSL8 To maintain symmetry nyx nxy Ey Ex nzx nxz Ex Ez nzy nyz Ez Ey and to obtain a valid material nxy lt Ex Ey nxz lt Ex Ez 2 nyz lt Ey Ez 2 Material properties orthotropic thick e g QSC4 To maintain symmetry nyx nxy Ey Ex and to obtain a valid material nxy lt Ex Ey Notes e Option 16 can be used to override non convergence as a result of poor conditioning When Option 16 is specified and an increment has failed to converge within the maximum number of iterations allowed LUSAS assumes convergence writes
318. gt Point menu item with the desired element sizes for use at assigned points on the background grid For example Point mesh spacing attributes of 0 5 and 2 5 might be used for opposing corners of the grid and a spacing of 2 0 might be used for the remaining points Assign the Point mesh attributes to the appropriate Points on the Background Grid All points must be assigned a point mesh attribute Define a Surface or Volume mesh attribute with an Irregular mesh type leaving the element size blank Select the Surface or Volume and assign the Surface or Volume mesh attribute to the model selecting the From background grid in the mesh assignment dialog The mesh generated will be based upon the governing point mesh values defined for the background grid Ooo Element size 0 5 Element size 2 0 The background grid Element size 2 0 Element size 2 5 SSS i 133 Modeller Reference Manual Composite Material Assignment When a Volume feature with a composite material assignment is meshed the nodes are moved onto the composite layer boundaries This ensures an exact number of layers in each element COMPOSITE LAYUP SEQUENCE MESH ADJUSTED TINE AUTOMATICALLY TO LAY ON INTERLAMINA BOUNDARIES WHEN gt 1 THROUGH DEPTH Connecting Beam and Shells Beam Shell Connectivity Beam Solid Connectivity Extend the beams along the edge of the Extend the beams along the edge of the solid shell indicated by thick lines elements in
319. h as Personal An empty Personal button group will be added to the Modeller user interface 45 Modeller Reference Manual Customising toolbar groups Toolbar buttons can be added to exiting toolbar groups or placed on new toolbar button groups Use the Customise tab to select a toolbar category and then from the arrangement of buttons shown for that category drag and drop a toolbar button into an empty part of the user interface This can be repeated for as many buttons are necessary As each button is added the button group will enlarge to accommodate it Button groups can be docked alongside other button groups on the user interface by dragging and dropping into place Buttons may be removed from toolbar groups by holding down the Alt key and then dragging the button into the View window Creating user defined toolbar button actions Nine user definable toolbar buttons are provided for linking to a specified action With the Customise tab selected these can be seen if the User entry is selected in the Categories list Scripts can be recorded and specified to be played when a particular user defined toolbar button is selected In Modeller use File gt Script gt Start Recording to record an action to be taken such as the adding a Contours layer to the Treeview and the selecting a particular entity such as Force Moment and a component such as Mz for example Then use File gt Script Stop Recording to save the scri
320. h elements the sign convention for bending moments for a particular element may change after re activation e g it is recommended that BSL4 should be preferred to BSL3 so that the 4th node is used to define the local axes and not the initial element curvature e Care should be taken when deactivating elements in a geometrically nonlinear analysis especially if large displacements are present It may be necessary to apply prescribed displacements to deactivated elements in order to attain a required configuration for reactivation e It should be noted that the internal forces in the elements will not balance the applied loading until all residual forces in activated deactivated elements have been redistributed 226 Chapter 6 Thermal Surfaces and Heat Transfer The thermal surface facility allows thermal gaps contact and diffuse radiation to be modelled Thermal surfaces are used to model the thermal interaction of two distinct bodies or two different parts of the same body through a fluid medium LL Thermal Gaps are used to model gaps between structures that are relatively close together LI Contact is used in a thermo mechanical coupled analysis where contact takes place and the contact pressure effects are then included in the analysis Q Diffuse Radiation is the process of heat transfer from a radiation surface to the environment or to another thermal surface defining the same radiation surface Radiation is modelled by specify
321. he stiffness of the close contact spring is 10 3 that of the slideline stiffness It s stiffness is controlled by the Solver system parameter SLSTCC For analyses that continue to suffer from chatter the size of the close contact region should be increased and the value for SLSTCC reduced accordingly SLSTCC can be changed via File gt Model properties gt Solver system variables The close contact facility is not available for explicit dynamics Temperature Dependency Choosing the Temperature dependent check box allows different sets of slideline properties to be specified at different temperatures thus providing temperature dependence With temperature dependency the stiffness scale factors and the coefficient of friction are linearly interpolated across the reference temperatures All other properties remain unchanged Pre contact Pre contact is used to overcome problems encountered when applying an initial load other than Prescribed Displacement to a discrete body that without the slideline would undergo unrestrained rigid body motion This is particularly the case when an initial gap exists 23 Modeller Reference Manual between the contacting surfaces and a load is applied to bring them into contact Pre contact is only applicable to static analyses P s s i Pre contact brings two bodies into initial contact by using interface forces that act between the slideline surfaces in order to avoid unrestrained r
322. he Use button to use a transformation defined from Points in selection memory e A transformation is not updated when the points defining it are changed 102 Chapter 4 Compound Transformations Saved transformations may be used together to create a compound transformation 1 e two or more transformations can be performed on selected geometry at once To carry out a compound transformation firstly from the Utilities gt Transformation menu item define the required transformations and save them with suitable names Then when copying moving or sweeping select the Compound option and specify which transformations to use by adding them to the right side box Single transformations may be used more than once if required The order in which the transformation is performed is significant therefore click the up and down buttons to get the correct order starting from the top Merging and Unmerging Features When a new feature is generated if its position coincides with an identical feature then by default the two features will be merged removing one of the features provided the merge characteristics are satisfied In addition to the automatic merging carried out during feature generation any combination of features can be merged at any time Care should be taken to merge from the lower order features upwards as higher order features can only merge if defined by the same lower order features Merge Unmerge Commands The following merge un
323. he behaviour can be represented mathematically first moment of area A standard section property used to determine the position of the centroid The first moment of area about the x axis is defined as the integral of x with respect to the area of the section First moments of area are zero for symmetrical sections See also second moment of area product moment of area fixed disk See hard disk fleshing The display of a bar or beam element in its true cross sectional form 438 Index floppy disk A disk that can be inserted in and removed from a floppy disk drive Also known as diskette See also hard disk disk drive flow rule The process by which the direction of plastic straining is calculated See also associative plasticity non associative plasticity flux The rate of flow of heat usually expressed per unit area foam model Also known as crushable foam See volumetric crushing model force diagram The graphical display of axial or shear forces on the graphics screen See also axial force shear force bending moment diagram follower force See non conservative loading forced response See harmonic response forward Euler An explicit plasticity formulation whereby the direction of plastic straining is computed as the yield surface is intersected See also backward Euler Fourier Transform A method for finding the frequency content of a time varying signal Fourier analysis Analysis of an a
324. he information in a Modeller results file is stored in a compressed binary format and may only be accessed using LUSAS Modeller History Files History files are used to output the named variables and selected node and element results from LUSAS Solver in an ASCII format Specification of the node and element numbers to be output to this file is defined from the File gt LUSAS Datafile menu item The output frequency for incremental analyses is controlled using analysis control The results stored in the time history file can be accessed for graphing The history file format consists of a header section with a title list of named variables type of nodal results and type of element results followed by the results for each time increment number The format is shown below Note Due to space limitations the number format has been adjusted Standard history files will contain accuracy to machine precision The named variables selected nodal results and selected element Gauss point results will be output for each time step or increment as specified in the analysis control Script Files Script file may be created and used to store a sequence of commands for later playback Script files are created in Visual Basic Script VBS format and are particularly useful for storing combinations of commands which are used frequently Uses include consistent reproduction of screen images for use in reports and use with startup templates to pre load the Attr
325. hear force Transverse force See also axial force stress resultant shear lag A delay or slow response in developing shear flow reactions to applied loads shear locking Causes over stiff performance in bending and occurs as a result of the bending deformation mode requiring strain energy storage by shear strain as well as by normal strain Also known as parasitic shear shear retention factor The factor by which the in plane shear modulus is reduced following formation of a crack plane in the biaxial concrete model See a so concrete model ductile fracture shell elements A form of plate element that considers both membrane and bending behaviour shifting A procedure used in eigenvalue extraction where the stiffness matrix is shifted to overcome numerical problems when rigid body modes are present SI units Units of the Syst me Internationale d Unit s The most relevant to finite element analysis are as follows Length metre m mass kilogramme kg time second s temperature Kelvin K force Newton N frequency Hertz Hz 461 Modeller Reference Manual singular See singularity skew angle A measure indicating a departure from orthogonality for a bridge deck Also used to specify the angle between reinforcement directions for Wood Armer calculations singularity A theoretical infinite stress or a condition found during solution which indicates that insufficient information has been provided to s
326. hen a file is selected the Advanced button can be used to specify import parameters After all feature entities have been imported a feature merge will be carried out according to the merge setting defined under Model properties Mesh data from supported interface files can be imported using the File gt Import Mesh menu item File Import Options Advanced Only those options applicable to the file being imported will be available for selection 57 Modeller Reference Manual Option Translate annotation type geometry entities Translate blanked entities Merge trimming lines Delete dependent geometry Delete points not defining lines Delete lines not defining surfaces Delete unconnected lines Use domain space trimming curves Lock the mesh post import Model is solid volumes Coalese volumes Create material groups Maximum number of groups Merge geometry post import Minimum line length Minimum angle degrees Pre translation scale Radius of curvature to length ratio Parsing error limit Entity types to exclude Description Include entities marked as annotation Include entities marked as blank Attempts to merge the trimming lines of trimmed surface entities Will delete geometry objects created from entities marked as dependent All points not connected to a line are removed All lines not connected to a surface are removed Deletes unconnected lines that do no
327. hen be assigned to the required Line s in the model Notes e The mesh used to compute arbitrary section properties determines the accuracy of the section properties but also affects the computation time It has been found that a reasonable result is achieved if at least two elements are used through thin sections of the model If a finer mesh is required it is recommended that the problem is initially set up using the default mesh and then the Automatic Meshing option is switched off to allow the mesh to be adjusted e For thin curved sections the shear areas calculations are approximate e Sections constructed of two or more materials can be accommodated using the modular ratio approach Firstly an isotropic field material property attribute is created with both the thermal conductivity and the specific heat set to unity and this attribute is assigned to surfaces made from the primary material Further material property attributes are then defined for each secondary material with the thermal conductivity set to G1 G2 and the specific heat set to E1 E2 where G1 is the shear module of the primary material G2 is the shear modules of the secondary material E1 is the Young s Modulus of the primary material E2 is the Young s Modulus of the secondary material These material attributes should be assigned to the appropriate surfaces before running the arbitrary section property calculator e User defined beam cross sections need to ha
328. his second eigenvalue analysis utilises the previous results in order to compute the extra eigensolutions thus saving on computational effort Note that this option is not available with the Fast Lanczos solver although repeated eigenvalue analyses may be performed during a run by re specifying the eigenvalue control Convergence Of Subspace Iteration As the procedure iterates it is necessary to refer the numerical solution to a criterion with which to measure its convergence It is assumed that the eigensolution has converged on iteration k when Sa i _ lt rtol rk l for all eigenvalues Ai Starting Vectors for Subspace Iteration The first step of the subspace iteration method is the computation of the starting iteration vectors Two methods of constructing these starting vectors are available in LUSAS One method is based on the observation that the vectors should be constructed to excite the degrees of freedom associated with a large mass and a small stiffness Alternatively the starting iteration vectors can be obtained by using the solution from a Guyan reduction analysis This method allows you greater freedom in selecting the starting iteration vectors The starting vectors are defined by specifying master freedoms within the retained freedoms 293 Modeller Reference Manual as for a Guyan reduction analysis Then the eigenvalue control properties are used to control the eigenvalue extraction but a Guyan reducti
329. ialog e Using the Attributes gt Geometric gt Tapering Section menu item to access the geometric line tapering section dialog directly 147 Modeller Reference Manual e Using the Attributes gt Geometric gt Multiple Varying Section menu item to create a geometric line attribute that contains details of any number of cross sections held in section libraries that are to be assigned to a line or a whole series or path of lines at specified distances See Multiple Varying Sections for details The following options are available when defining geometric line properties Q Visualise Cross sectional shapes for standard library items and for library items created by the standard and arbitrary section property calculators will be automatically visualised Beam sections defined by using the Attributes gt Geometric gt Line menu item requiring general properties to be entered by hand will require cross section properties to be defined manually in order for geometric visualisation to take place The orientation of the visualised section is based upon the vertical axis defined for the model In LUSAS 2D models are assumed to be drawn in the XY plane with the Y axis vertical 3D models normally have the Z axis set to be vertical Q Tapering Non Tapering Tapering beam sections can be defined by specifying section properties for each end of the beam For complex sections this would normally be done by drawing selected cross sections for key lo
330. ibed ending with details of how the Grid Tab can also be used to check or add layer data 1 Define the Layup Click on the New button to define a new layer Enter a unique lamina name select a composite material and enter thickness and layup angle values Note that a lay up sequence is defined from bottom to top The name may given a suitable prefix in the box provided Click the OK button 2 Enter details for the next lamina 3 Repeat this process for each layer as required If a symmetric layup sequence is to be defined check the Symmetric button This duplicates and reverses the layup sequence previously entered The Reverse button is used to upturn the defined stack so the uppermost layer becomes the bottom layer The Insert button can be used to add layers between existing layers 4 Check the Layup sequence There are two ways to check the composite layup sequence LI Select the Visualise button to display a representation of the defined composite layup If desired this image can be annotated to the screen by clicking on the Create Annotation button from the visualise dialog LI Select the Grid tab to display the layer properties in grid format Data may also be created or edited using this option Pressing the Tab key with the cursor sitting in the last row and cell of the grid creates a new row populated with the same data as the previous row A right mouse click in a row opens a context menu that allows rows to be inserted or d
331. ibutes Treeview with selected attributes for a particular analysis set default mesh or material types or define preferred colour schemes 53 Modeller Reference Manual Scripts are normally run by opening the file in a file browser but user defined toolbar buttons can be set up to run scripts Script file manipulation is controlled from the Files gt Script menu item The following functionality is available E oa Run Script An existing script file is replayed by choosing it from the Open dialog Q Start Recording creates a script file If a non default file extension is specified or if the file already exists you will be prompted for confirmation before proceeding Existing script files can be appended to if required While recording all attempted commands are logged to the script file using the LUSAS scripting language LI Stop Recording closes the script file Session and Recovery Files Each time Modeller is run or the model is saved a new recovery file is created in the current working folder This recovery file is named after the model name with the rev extension Every attempted command whether entered from the user interface or via the command line is logged in this file using the scripting language When the model is saved or the user exits Modeller the recovery file is renamed to a session file with an incrementing version number Picture Files About Picture Files LUSAS picture files may be used for storing graphical i
332. ic Equivalencing Automatic equivalencing can be activated from the Meshing tab of the Model Properties dialog This will equivalence all features in the model on meshing if they are within the default equivalence tolerance or within an assigned tolerance Note Remeshing occurs each time a relevant command is issued but a forced remesh is possible using the Utilities gt Mesh gt Mesh Reset menu item Automatic equivalencing can be time consuming for models with a large number of nodes 221 Modeller Reference Manual Visualising Equivalences Displays the features which have a specified equivalence assigned to them in a chosen colour and line style In this example different equivalence tolerances are assigned to different parts of a model to merge more coarsely or finely as required Using visualisation the lines to which the equivalence is assigned can be highlighted Equivalenced nodes can also be visualised as they are removed In this diagram they are shown using the square symbol Summary e More than one equivalence attribute may be defined in order to rationalise more than one section of the model independently e More than one equivalence attribute can be assigned to a feature to equivalence it within a different subset of the model e A check for unconnected elements and nodes can be performed using an outline mesh plot Mesh layer properties or by checking for duplicate node numbers using the View gt Browse sel
333. ic analysis in which the effects of thermal inertia are included i e specific heat transient response System response that is not periodic transition mesh A mesh generated on a regular surface where the number of divisions on any two opposite boundary lines are unequal Tresca stress The scalar stress state obtained by combining the individual component stresses at a point according to the classical Tresca failure criterion Typically used in the failure of soil or granular type materials See also Drucker Prager stress triaxial A description of a material model in which three axes are considered to determine the material response See also biaxial uniaxial TSR An acronym for terminate and stay resident program See also memory resident program 467 Modeller Reference Manual unaveraged nodal results Most results are calculated at the Gauss points of an element and then extrapolated to the nodes When the results from the elements joined at a node are extrapolated to the nodes but not averaged together these are known as unaveraged nodal results See also averaged nodal results smoothing undeformed mesh A mesh displayed in its original shape without any imposed deflections See also deformed mesh under damped system A system which has an equation of motion where the damping is less than critical It has an oscillating impulse response unified creep A creep formulation whereby creep and plasticity are
334. ic features 103 mesh 98 119 mesh divisions 120 mesh lock 137 mesh objects 15 Mesh only models 16 mesh reset 137 mesh utilities 136 meshing techniques 129 Mesh only models 16 message window 9 minimum value plots 343 mirror plane 100 modal dynamics 335 model file 50 Model Properties 18 model types 15 modeller licence selection 13 Modeller Results Files 53 Mohr Coulomb material model 170 moving geometry 99 Multiple varying sections 153 Modeller Reference Manual distance types and methods of assignment 157 named components 33 natural frequency analysis 292 Negative Jacobian Errors 399 Negative Pivot 402 nodal equivalencing 220 nonlinear 187 nonlinear analysis 162 281 287 Non Orthogonal Model Views 412 Non structural mass elements 140 O Offsets 149 multiple varying sections 155 optimiser 309 orientation of geometry 111 Orthogonal Model Views 412 orthotropic material model 164 output 317 343 368 370 P page layout 39 panning 37 patch load 201 Paths 267 PATRAN 66 PDSP TPDSP loading 218 peak value plots 343 pen library 26 478 pentahedral 92 picture files 54 pictures 374 Pivot Errors 403 pivot problems 399 Planar 76 Plastic 149 playback script 54 Plotting results for attributes 351 Plotting results for groups 350 plotting results on a graph 365 plus elements 144 point feature 69 75 point load 201 po
335. ication of critical state soil and clay material behaviour e The volumetric crushing indicator effectively defines the unloading behaviour of the material If there is no volumetric crushing the same pressure logarithm of relative volume curve is used in loading and unloading and if volumetric crushing takes place the alternative unloading reloading curve is used see Ist figure e Log relative volume Natural logarithm loge not log10 of relative volume coordinate for ith point on the pressure logarithm of relative volume curve see Ist figure e The pressure logarithm of relative volume curve is defined in the compression regime hence logarithms of relative volume must all be zero or negative and the pressure coordinates must all be zero or positive 183 Modeller Reference Manual Generic Polymer with Damage Model 89 The Generic Polymer with Damage model appears under the Attributes gt Material gt Specialised menu item The model accounts for strain rate behaviour and irrecoverable damage in the modelling of polymers and other materials The model consists of a set of Maxwell dampers which are used to model visco elasticity an Eyring dashpot which is used to model viscoplasticity and a linear spring These components are placed in series The Properties of the Maxwell elements Eyring dashpot and linear spring can be different in tension and compression Material Properties Q Eyring damper activation energy LI Eyring damper
336. ide basic information about whatever is under the cursor The data tip mechanism is only invoked when the cursor hovers over a model feature within the graphics window If more than one item is present at the location on the screen you may use the Tab key to cycle between all possible selectable objects with the data tip updated each time As additional feedback if a object is selected dynamic selection is invoked to highlight each object as it becomes the focus Thus with two intersecting lines or overlapping surfaces it is clear which one is being displayed in the data tip Pressing the Enter key whilst a data tip is active adds the current object to the selection This provides an easy way to select a specified one of many objects at a given location Getting Help LUSAS contains a comprehensive Help system The Help consists of the following L The Help button re on the Main toolbar is used to get context sensitive help on the LUSAS interface Click on the Help button then click on any toolbar button or menu item even when greyed out LI Help Topics accessed from the Help menu provides access to the Help files They include the Modeller Reference Manual reference help files such as the Element Reference Manual and access to other manuals that are available in PDF format such as the Examples Manuals Theory Manuals and Solver Reference Manuals LI Every dialog also includes a Help button which provides information 12 Chapte
337. ies given in the appropriate element section of the theory manual need to be adhered to Numerical instabilities may result when the material characterisations approach their limits see Notes on material properties orthotropic for a list of these inequalities 401 Modeller Reference Manual LI Support nodes typical mistakes e The structure has not been restrained against free body translation and rotation Each of the above suggestions are of interest because they make a contribution to the stiffness matrix A further possibility is that the LUSAS Modeller model geometry is invalid because the element mesh contains gaps or has discontinuities in the connection of the elements Such modelling problems may be found in LUSAS Modeller by e Using the Mesh layer to view only the outline of the mesh The view will show lines wherever a discontinuity occurs e Using the Labels layer to draw the node numbers onto the mesh to see if any node numbering is overwriting at any point indicating two nodes at the same point Correction would normally require either a merging or an equivalencing operation The diagonal decay message is closely related to the small pivot WARNING message see below See also the additional notes in the Theory Manual regarding the Gaussian solution method Small Pivot Warnings See the section titled Diagonal decay warnings Negative Pivot Warnings And Errors A negative pivot could be the result of poor c
338. iewing results the material transformation should be used to display stresses on or off axis Local Coordinates Local Coordinates define coordinate systems that differ from the default global Cartesian system Local coordinates are defined from the Attributes gt Local Coordinate menu item and have several uses L Geometry Definition Geometry features may be defined in a local coordinate system by set the chosen local coordinate active When a local coordinate is active all dialog entries relating to global X Y and Z coordinate input use the transformed axis set as a basis for input Local Coordinate 1 P3 19 10 5 0 T origin at P2 P Global Local X at P3 i _ P4 5 0 0 Y NZ Local 1 X P2 10 3 0 P1 0 0 0 Global Global Q Transforming Nodal Freedoms When assigned to features the effect is to transform the degrees of freedom of the underlying element nodes This has the effect of transforming the directions of applied global load and support conditions In the example below global freedoms are transformed to radial directions by assigning a cylindrical coordinate to the Lines around the hole This method of transforming nodal freedoms is only valid for small deflections since the freedom directions are not updated during analysis 248 Chapter 6 Q Materials A local coordinate may be used to align orthotropic and anisotropic materials Q Variations Variations may be defined using functions in terms of a local coordinat
339. ific thermal surface are viewed by setting the appropriate surface as only visible from the group context menu For 3D problems contours of the thermal surface results may be displayed on the thermal surface Values and vectors can be displayed for both 2D and 3D problems The results on a thermal surface are displayed by selecting the Thermal Surface Results entity on the appropriate property dialog Thermal surface results may be printed using the print results wizard Thermal surface flow results Label Gap and environmental flow GapEnvFlw Radiation flow between segment RadFlwSeg Radiation flow to environment RadFlwEnv Total nodal flow TotalFlw Plotting Results on a Graph The Graph Wizard is used to draw XY graphs The following results graphs may be plotted if the results are available LI Time history A history for a specified results type throughout an analysis with respect to time or increment Graphs may be plotted for a named variable such as Total Load Factor or Response Time verses a specified results quantity such as displacement in X equivalent stress or sum of reaction over a set of specified nodes The following history datasets are available Nodal Averaged or summed Gauss Point results for a selected element and Gauss point Element Gauss numbers may be determined using the labels layer Named Named result variables for a linear analysis such as loadcase ID a transient analysis such as response time or
340. igenvalue results User content Data to display Preview D LUSAS144 Projects frame analysis bmp Add file OK Cancel Help The User Content tab of the Chapters dialog allows images or text files to be added to the report using the Add file button The Capture screen button takes a snap shot of the current Graphics Area and allows saving it as a fixed size BMP JPG or WMF file to the working folder by default or to any other specified folder Clicking the OK button adds this image to the report as a separate chapter Only BMP files currently appear in the preview pane Each image added to the report is added as a separate chapter Note It is possible to visit this dialog several times to create multiple chapters Once created the order of chapters in the report can be modified at any time by dragging and dropping them up and down the Report Treeview Chapter Extent The extent of data that the chapter is to report on can be specified by selecting either LI Elements showing results prints results only for those elements that are displaying them in the Modeller view window Q Visible model prints results all elements that are visible in the Modeller view window Q Full model defaults option which prints results for all elements of the model regardless of whether the elements are visible or displaying results in the Modeller view window Q Specified group prints results for a specified n
341. igenvalues loadcases In this case the modal forces are complex and therefore the modal forces are stored in two arrays one for the real component and one for the imaginary For excitation types other than these the imaginary components will always be zero Note that it is assumed that all applied forces are in phase The chosen load vector need not be in the same results file as the eigenvectors used for the response calculation typically only one load vector will be stored with the modes LI Support Motion To set the modal excitation to support motion This is used when all the supports move together for example in the analysis of an earthquake or when a small component attached to an airframe or vehicle chassis has a known vibration level The calculations are based on participation factors calculated by LUSAS Solver A participation factor defines the modal force resulting from a unit acceleration loading applied to the whole model in a specified direction The participation factors for each mode in each of the global directions are stored in the results file and are used as modal forces in the support motion calculations X Y Z direction motion or motion in any vector direction can be represented General support motion can be modelled by applying a unit acceleration field to the model using body force loading and selecting the resulting equivalent nodal forces as modal excitation In the frequency domain absolute or relative support motio
342. igid body motion These forces act in a direction normal to each surface One of the surfaces must be free to move as a rigid body and the direction of movement is dictated by the interface forces applied loading and support conditions The facility allows a gap to exist between the surfaces In the example above pre contact is defined for slideline 1 but not for slideline 2 Warning Incorrect use of this procedure could lead to initial straining in the bodies or to an undesirable starting configuration By selecting specific slidelines for the pre contact process i e slidelines where initial contact is expected minimum initial straining will occur and more control over the direction of rigid body movement can be exercised Contact Cushioning Contact cushioning can be used when convergence difficulties related to in contact out of contact chatter are experienced The formulation applies a contact force and stiffness above a surface that increases exponentially as a node moves closer to the surface This cushions the impact of a node with the surface and softens the transition between in contact and out of contact states Contact cushioning can therefore help improve nonlinear convergence when chatter is encountered and the set of active contact nodes is continually changing See Theory Manual for details Initial slideline type The slideline type at the start of the analysis as described earlier Type changes during analysis Selec
343. iles 114 Chapter 5 Chapter 5 Model Attributes Introduction Attributes are used to describe the properties of the model Attributes are assigned to geometry features or to mesh objects in a mesh only model and are not lost when the geometry is edited or the model is re meshed Attribute assignments are inherited when geometry features are copied and are retained when geometry features are moved The attribute types are General Attributes LI Mesh describes the element type and discretisation on the geometry LI Geometric specifies any relevant geometrical information that is not inherent in the feature geometry for example section properties or thickness LI Material defines the behaviour of the element material including linear plasticity creep and damage effects LI Support specifies how the structure is restrained Applicable to structural pore water and thermal analyses Q Loading specifies how the structure is loaded Specific Attributes Q Local Coordinate provides a transformation for loads and supports and an alternative to the global coordinate system LI Composite defines the lay up properties of composite materials in the model LJ Slideline slidelines control the interaction between disconnected meshes LI Constraint Equation provides the ability to constrain the mesh to deform in certain pre defined ways LJ Thermal Surface defines thermal surfaces which are required for modelling thermal e
344. in normal cursor mode Rotation zoom and pan model manipulations are applicable for all cursor input modes including normal cursor selection of features defining lines by cursor or when section slicing For larger models when the refresh time is significant the model display will reduce to an outline view when using rotate zoom and pan Rotating the Model Three methods of rotating the view of the model are available each one is a button on the View toolbar E Dynamic rotate Allows the model to be rotated dynamically using the cursor The model rotates around various multiple axes when the cursor is moved By holding down the Control key the Control and Shift keys or the Shift key while using the dynamic rotate the model can be rotated independently about the screen Z Y and X axis respectively Click on the normal cursor to return to selection mode Note also that holding down the Alt key provides a one key option for rotating about the the screen Y axis 37 Modeller Reference Manual Note Models are dynamically rotated using the model ball method With this method a model can be imagined to be surrounded by a sphere such that a mouse click and a drag of the cursor on the screen represents clicking on the surface of the sphere and dragging to rotate it to a new position In doing so it is important to note that the model rotation is restrained to rotate only around the model s vertical axis as defined on the Verti
345. in terms of geometry features which are sub divided into finite elements for analysis This process is called meshing Mesh attributes contain information about 119 Modeller Reference Manual LI Element Type Specifies the element type to be used in a Line Surface or Volume mesh attributes may be selected either by describing the generic element type or naming the specific element See Element Selection LJ Element Discretisation Controls the density of the mesh by specifying the element length or the number of mesh divisions spacing values and ratios Q Mesh Type Controls the mesh type e g regular transition or irregular Mesh attributes are defined from the Attributes gt Mesh menu item for a particular feature type i e Point Line Surface or Volume The mesh attributes are then assigned to the required features Various techniques exist for meshing different types of models and are described below For feature based geometry models mesh attributes are defined from the Attributes gt Mesh menu item for a particular feature type 1 e Point Line Surface or Volume The mesh attributes are then assigned to the required features The orientation of the model Geometry is used to define the local axes of the elements See Changing Geometry Element Orientation if element axes need to be changed Mesh only models Mesh only models are comprised of nodes and elements and do not contain any geometric feature types or indeed any geo
346. in the Stress results entity and the results components available will depend upon the element type see Element Reference Manual The diagrams may be drawn using the element axes or screen axes The following quantities may be represented Q Axial Forces local x direction beam forces Q Shear Forces through thickness shear forces LI Bending Moments bending moment results LJ Torsional Moments 349 Modeller Reference Manual Scale 1 143 095 Zoom 100 0 Eye 0 67736 0 57735 0 57735 97 796 Eigenvalue Analysis Enveloping on hly Enveloping Whole earthquake_MAX 17 758 235 559 08311E3 Maximum Displacement 0 2516E 01 at Node 79 71 795 63 968 Entity Stress 68 5 18785E3 Bosasees 7428763 31648E3 9185E2 Diagram Component My 702 622 i 0691E3 93014E3 MAX 0 24865E 05 at EIKGP 3 4 694 486 8 21784E3 04 836 7872E3 MIN 6 660 at Elt GP 9 6 5627E3 Ps 16 9792E3 DIAGRAM Scale 140 1667 46242E3 05281E3 101463 275E3 BO887E3 922 235 46391E3 10 093 18 8547 E3 i eee 48096E3 14 4014E3 30 126 4 02167E3 yor 18 281E3 51722E3 306 915 9859E3 6034E3 20098E3 55387E3 72 995 47281E3 OARRES 9966E3 16955E3 12862E3 15 67 171 1 2183E3 17 1035E3 ETR 15 5641E3 lasmi 74181E3 1901E3 Ee pease 45705E3 16604E3 14 38E3 818 174 1 41851E3 B485E3 68324E3 5 86777E3 44175E3 By default results are computed and displayed on the visible model When appropriate layers are present in Layers LK Treeview results can be selectiv
347. indow may be selected with the cursor by clicking on them individually or by dragging over an area Following selection items may be added or removed from the initial selection by carrying out further selections based upon either menu choices or upon particular keystrokes used Area selections Regions or areas of the model may be selected as a rectangular a circle or a polygon either using the appropriate toolbar buttons or the keyboard short cut C3 To select a rectangular area click to define one corner hold the mouse button down and drag the cursor to the opposite diagonal corner Pick the circle selection tool or hold down the C key then select the centre of the circle and drag the edge of the circle to the required radius K Pick the polygon selection tool or hold down the X key then select each corner of a polygon and either double click to close the polygon or select Close Polygon from the context menu It is invalid to define a vertex which would cause two lines on the perimeter to cross Because more than one click is needed to define a polygon individual items may not be selected whilst in polygon select mode Notes e Holding down the Shift key whilst selecting items will add the newly selected items to those currently selected 28 Chapter 2 e Holding down the Control key while selecting items will enable the selection state of the item selected to be toggled e Holding down the Shift and Control keys while se
348. ine is required To use an existing line or annotation line instead of indicating the cut using the cursor the line or annotation line should be selected before choosing the Utilities gt Graph through 2Dmenu item 354 Chapter 8 Notes e Care should be taken when slicing through voids or holes in the model as this can give misleading results e Care should be taken when slices pass through parts of the model with non uniform properties such as parts of different materials or of different thickness e Sometimes due to model size grid points are too close together to be usable In these cases simply increase the grid size so that individual grid points can be selected Graph Wizard Two types of graphs may be plotted LI Results quantities Any available result entity may be plotted against distance along the slice Q Axial force and bending moment This generates three datasets of distance axial and bending stress along a line through a section the axial force per unit width moment per unit width and distance of the neutral axis to the midpoint of this line For axisymmetric solids the moment per unit radian is printed as well From these datasets graphs of axial and bending stress versus depth of section are plotted For more details on viewing results on graphs see Plotting Results on a Graph Displaying Beam Stresses Beam stresses can be displayed on the fleshed section or at selected fibre locations These stress
349. ing a deformed mesh for re use in a new analysis LJ Annotation adding of text line bitmap and border annotation to the view window Q Transformation moving mirroring and copying of geometry Q Heat transfer specification of thermal gap properties and radiation surfaces Q Variation varying attributes over features LI Reference Path defines a path along which a set of multiple varying sections can be assigned LI Loadcase adds a new empty loadcase to the loadcase treeview Q Load Curve used to describe the variation of the loading in nonlinear transient and Fourier analyses LI Envelope create an envelope of maximum and minimum effects LJ Combination combine results from different loadcases with different load factors to get max and min effects LI Fatigue calculate fatigue life and number of cycles to failure Q IMD Loadcase create a loadcase for use with interactive modal dynamics Q IMDPlus the investigation of various dynamic responses using the results from an eigenvalue analysis LI DesignF actors assess the reserve strength capacity of a component or structure 20 Modeller Reference Manual LI Set Fourier Angle specify the angle around the circumference at which Fourier results are required Q Background Grids grade the mesh pattern locally when irregular surface meshing LU Graph Wizard plot results on x y graphs Q Animation Wizard animate the mode shapes or load history of a structure Q Sec
350. ing radiative properties for thermal surfaces Thermal surfaces Thermal Surfaces are the thermal equivalent of structural slidelines They are defined from the Attributes gt Thermal Surface menu item and are assigned to features of the model and manipulated in the same way as all other attributes A thermal surface must be defined before thermal gap or radiation properties can be specified LJ Radiation properties are required when defining a radiation surface for heat transfer by radiation exchange Q Environment properties are required when thermal environment properties exist Used for heat transfer to the environment convection and conduction Thermal Surfaces work in conjunction with Thermal Gaps and RadiationSurfaces See below for details Heat Transfer Thermal gap and radiation surface properties are used to dictate the type of heat transfer that can take place between Thermal Surfaces They are defined from the Utilities gt Heat Transfer menu item As utilities they cannot be assigned directly to features of the model as Thermal Surfaces can A thermal surface must have been defined prior to specifying any thermal gap or radiation properties The process of thermal surface heat transfer definition is summarised in the following diagram 22 Modeller Reference Manual Q Thermal Gaps Thermal gaps are used to model heat transfer across a gap and heat transfer by contact when a gap is deemed to have closed If these eff
351. ingle Finite Element to a known stimulus we can build up a model for the whole structure by assembling all of the simple expressions into a set Modeller Reference Manual of simultaneous equations with the degrees of freedom at each node as the unknowns These are then solved using a matrix solution technique For a mechanical analysis once the displacements are known the strains and stresses can be calculated For a thermal analysis the gradients and fluxes can be calculated from the potentials Finite Element Analysis with LUSAS Finite element analysis using LUSAS software involves three stages 1 Creating the finite element model 2 Running the analysis 3 Viewing the results Each LUSAS software package consists of Q LUSAS Modeller a fully interactive graphical user interface for modelling and viewing of results LJ LUSAS Solver a powerful finite element analysis system Modelling Modelling involves creating a geometric representation of the structure assigning attributes and outputting the information as a formatted data file dat suitable for processing by LUSAS Solver See Using LUSAS for a quick introduction to the LUSAS Modeller interface Creating a Model A model is a graphical representation consisting of Geometry Points Lines Surfaces and Volumes and Attributes Materials Loading Supports Mesh etc The model is created by Defining the Geometry and Attributes and Assigning the Attributes to the Geometry
352. ining the mass terms in a finite element analysis See a so consistent mass lumped mass 447 Modeller Reference Manual mass normalisation Normalisation of eigenvectors with respect to mass Must be carried out when eigenvalue results will be used to calculate harmonic or spectral response See also normalisation harmonic response spectral response master freedom Freedoms at which the mass contribution of the inertia effect is considered to be significant See also slave freedom Guyan reduction master index table The master index table is an area of memory that stores an overhead associated with every load case increment or time step dump to a plot or restart file master slave Terms used to signify paired sets of attributes where the action of one item is subservient to the action of the other This term is used in the assignment of slides joint interface meshes and constraint equations material properties Describe the stress strain relationship and or thermal properties of an element matrix properties A material model used only for joint elements that allows direct definition of linear properties of stiffness mass or damping mechanism A deformation mode which has no associated energy and is not a rigid body deformation and is therefore unrestrained Usually obvious in elastic problems but can have more subtle manifestations when using material or geometric nonlinearity memory resident program A program that is
353. int mass 140 polymer material model 184 pore pressure 179 190 power spectral density 340 prescribed loads 200 printed output 370 Printing and Saving Pictures 374 properties 162 223 227 properties dialog 9 PSD response 335 Q quadratic elements 121 radiation properties 227 Real numbers 419 record script 54 Reference path 267 report add chapter 376 add eigenvalue data 380 add image 381 add loadcase data 379 add model data 377 add user data 381 creating 376 creating subreports 383 delete 388 exporting 385 printing 388 results subchapter 378 spreadsheet output 386 viewing 382 word output 387 report generator 375 report template 375 reports 375 resize the model to fit the screen 37 results 317 322 323 343 365 368 results file 317 319 retained freedoms 219 reversing geometric features 111 right click menu 9 rigidities 166 RIHG loading 217 rotating the model 37 rubber material models 180 S saving a view 26 scaling geometry 99 script recording 44 45 script files 53 479 Index Scripts running with toolbar buttons 46 scrolling the model 37 search areas 209 processing loads outside 212 section library 152 Section property calculation 274 multiple varying sections 156 section through the model 353 seismic isolator 187 selecting model features 28 409 selection memory 32 Selection Modifiers 410 server sections
354. inted form Application Manual Bridge Civil amp Structural e Describes the bridge civil and structural application specific features of LUSAS and their uses Chapter 1 e Available in PDF and printed form Autoloader Reference Manual e Provides detailed reference material for Autoloader a bridge loading optimisation module for use with LUSAS e Available in PDF form IMDPlius User Manual e Contains details of how to carry out multiple loading events with advanced loading conditions for two main uses seismic response analysis of structures subjected to acceleration time histories of support motion and for the analysis of 3D structures such as bridges subjected to constant moving vehicle or train loads e Provided in on line help format and also available in PDF and printed form Rail Track Analysis User Manual e Provides detailed reference material for the Rail Track Analysis option which permits track bridge interaction analysis to the International Union of Railways Code UIC 774 3 e Available in PDF form Element Reference Manual e Contains full element specifications This is the place to go to find out which functionality your elements support and what output you will obtain from your element selection e Provided in on line help format and also available in PDF and printed form Solver Reference Manual e The data files required by the LUSAS Solver can be edited directly with a text editor This manual contains
355. inted to the print results window by selecting the Display for slice s check box Note that the automatically created group name Slices is a collective name for the automatically created slice group names and does not contain results Results display and manipulation The results for each selected loadcase are displayed on a separate tab in the print results window A model info tab also appears in all output windows and provides basic information about the model When the Printed Results window is displayed a context menu can be invoked which allows for the printed results data to be manipulated Properties The number of significant figures or decimal places can be changed Sorting of data Results data can be sorted in ascending or descending order In addition data sorting can be achieved by double clicking on a header to sort by that column name A second double click on the same header will carry out a reverse sort Saving to a spreadsheet The contents of the current tab or all tabs can be saved to a spreadsheet or to a text file Copying to the clipboard Selected cells or the whole grid can be copied to the clipboard Printing The Print option sends the contents of the active tab to the printer ie Ox 42 LUSAS View Forces and Moments in Element Local Axes Loadcase 12 Results File Element a Gaussport Fz Mx MYC Element Gauss point Fz Mx My 10 i 1 2675 108 5697 2721 108 515 7
356. ion Second derivative of displacement with respect to time See a sovelocity acronym a word formed by the initial letters of words or by initial letters plus parts of several words For example FORTRAN is an acronym for FORmula TRANslator access The process of seeking reading or writing data on a storage unit active load case Each graphics window used in a LUSAS Modeller has an active load case set The active load case is marked with a dot in the Load case Treeview To set a new active load case click on another load case right click and choose Set Active from the shortcut menu Ina model file mdl attributes that have been assigned to load cases such as loading may only be visualised for the active load case e Ina results file mys results are displayed for the active load case adaptive analysis A series of analyses in which subsequent meshes are refined to reduce the overall errors in the solution analytical surface A Surface that can be represented by an analytical expression thus defining its internal geometry LUSAS supports cylindrical conical and spherical analytical Surfaces See a so ruled surface regular surface irregular surface angular acceleration A measure of the rate of change of rotational speed expressed in radians per second per second 421 Modeller Reference Manual angular velocity A measure of rotational speed expressed in radians per second animation Screens of in
357. ion Filter The advanced selection filter enables geometry nodes or elements to be selected based on a number of different criteria and is activated from the context menu Items may be selected by number or range or numbers for example 1T5I2 representing one to five in increments of 2 will select item 1 3 5 When a results only file is loaded the geometric and material attributes reflect the numbers in the solver data file Geometry can by selected according to the connectivity of the feature to surrounding features End Points Free Lines and External Surfaces can be highlighted in this manner Cycling through the Selection When features lie close together or overlap it can be difficult to select the required feature first time In these circumstances each separate press of the Tab key or click with the mouse at the same position selects a different feature The currently selected feature is displayed in the Status Bar at the bottom of the screen Alternatively click in the Status Bar to cycle the selectable features Or right click in the Status Bar to display a context menu from which Next Previous Closest or Furthest may be selected 31 Modeller Reference Manual 1 Hovering the cursor over a feature displays a data tip This shows the feature that will be initially selected with a cursor click Other items at the location are shown Each click of the mouse or press of the TAB key will select the next feature available
358. ion can be expressed along an element in terms of local or global axes domain A term used for the external boundaries of a finite element problem 433 Modeller Reference Manual double click To rapidly press and release a mouse button twice without moving the mouse Double clicking carries out an action such as starting an application double precision The use of two computer words to represent each number Allows the use of twice as many digits as normal to represent a number and allows for extra precision in calculations LUSAS is a double precision application draping The laying of a composite fabric over a surface draw The action of placing an entity onto the graphics screen Drucker Prager stress The scalar stress state obtained by combining the individual component stresses at a point according to the classical Drucker Prager failure criterion Typically used in the failure of soil or granular type materials See also Tresca stress ductile fracture A nonlinear material process by which tensile stresses are progressively released from a cracked Gauss point See also concrete model DXF An acronym for AutoCAD Drawing eXchange Format which can be read into LUSAS Graphics to form the basis of a model s features dynamic analysis Analyses in which the effects of mass are included This may be in the time domain using direct integration methods or in the frequency domain using eigenvalue extraction methods Also
359. ions are carried out in a specified order When a feature is moved or copied features will be merged as defined by the current merge status See Merging and Unmerging Features L Move When a feature is moved to a new location its lower order features will also be moved and its higher order features will be updated In the example shown here Point 3 is moved using an X and Y translation Due to feature associativity the definition of Lines 2 and 3 and of Surface 1 is automatically updated Moving can be used to separate features on a temporary basis to assist in the manipulation of features for example when defining slidelines or joints Note When moving holes the Surface is actually deleted and recreated so the feature numbers will not be maintained 99 Modeller Reference Manual LJ Copy Features may be copied any X number of times When a feature is gt copied its lower order features will e 5 also be copied using the same transformations Copied features will ty inherit the same attribute assignments as the original features In the example shown here the Line at the bottom is copied 4 times using a transformation in the X and Y direction Sweeping Geometry New geometry can be created by sweeping lower order geometry into higher order geometry using a transformation as for example by sweeping a Point into a Line or a Surface into a Volume To do so a transformation or sweep type needs to be specified
360. ions in explicit dynamics must be consistent with the central difference integration scheme Vij2 V 1 2 AoAt where V S12 2 are theselosiiee attics At 2 At 2 O is the acceleration at time 0 Only the initial velocity V actually relating to time Dt 2 can be defined in an explicit dynamics analysis The displacements d relating to time zero and accelerations A relating to time Dt are assumed to be zero Because of the nature of the central difference integration scheme an initial velocity will generate accelerations at time zero Accelerations relating to time zero are used to compute displacements at time Dt and will in fact be output at time At In general the values output at any time t will be 301 Modeller Reference Manual di Vt 1 2 At This means that in the output for any time step the displacements will relate to the current response time while the accelerations effectively lag one time step behind the displacements Impact Dynamics In addition to using nonlinear joint models to represent contact and impact a specialised procedure is available for modelling impact in dynamic analysis This procedure uses a slideline technique and permits the surfaces of 2D axisymmetric and 3D structures to register and react to contact with one another Coupled Analysis The flow of heat through a body and the corresponding distribution of temperature is described by the quasi harmonic equation the bod
361. is more obtainable e g for water Bulk modulus of fluid phase 2200 MPa NI e Two phase material properties can only be assigned to two phase elements e When performing a linear consolidation analysis transient control must be specified e Two phase material properties may be combined with any other material properties together with creep damage and viscoelastic properties if required See Solver Reference Manual for further details Hard Rubber Rubber materials maintain a linear relationship between stress and strain up to very large strains typically 0 1 0 2 The behaviour after the proportional limit 1s exceeded depends on the type of rubber see diagram below Some kinds of soft rubber continue to stretch enormously without failure The material eventually offers increasing resistance to the load however and the stress strain curve turns markedly upward prior to failure Rubber is therefore an E exceptional material in that it remains elastic far beyond the proportional limit Soft Rubber 179 Modeller Reference Manual Rubber materials are also practically incompressible that is they retain their original volume under deformation This is equivalent to specifying a Poisson s ratio approaching 0 5 The strain measure used in LUSAS to model rubber deformation is termed a stretch and is measured in general terms as dnew dold where dnew is the current length of a fibre dold is the origina
362. ist for calculating section properties of known cross sectional shapes Delete Section from Library Section properties may be deleted from either the local or server section library from the Utilities gt Library Management gt Delete Section menu item 2 8 Chapter 7 Chapter 7 Running an Analysis Preparing the Model for Analysis By default LUSAS will perform a linear static stress analysis Any other type of analysis requires the analysis control to be specified Analysis controls are properties of loadcases and loadcases are displayed in the Loadcase Treeview The model title and units are defined on the Model Startup dialog Consistent units must be used for all analyses The default solver is the standard frontal solver and is used unless the fast solver option has been licensed in which case the fast multi frontal solver is used An alternative solver may be set from the Solver Options dialog under the Model Properties gt Solution tab Solution Options may be set from the Element Nonlinear and Coupling dialogs under the Model Properties gt Solution tab Frontal optimisation is not required for the fast multi frontal solver and is off by default When no optimiser is specified the Sloan optimiser will be used to optimise the front width for the standard frontal solver An alternative optimiser may be selected from Optimiser Options dialog under the Model Properties gt Solution tab Analysis Types LUSAS may be
363. it method allows the proper definition of a tangent stiffness matrix which maintains the quadratic convergence of the Newton Raphson iteration scheme otherwise lost with the explicit method This allows larger load steps to be taken with faster convergence For most applications the implicit method should be preferred to the explicit method The model incorporates linear isotropic and kinematic hardening Uniaxial Yiel Stress O yo L1 Equivalent Plastic Strain p Nonlinear Hardening Curve for the von Mises Yield Model Model 75 Tresca Model 61 Material Parameters LI Yield stress The level of stress at which a material is said to start unrecoverable or plastic behaviour Q Heat fraction The fraction of plastic work that is converted into heat energy Only applicable to temperature dependent materials and coupled analyses where the heat produced due to the rate of generation of plastic work is of interest The value should be between 0 and 1 LI Slope of Yield Stress The slope of the uniaxial yield stress against equivalent plastic strain LI Plastic strain The limit of equivalent plastic strain up to which the hardening curve is valid 169 Modeller Reference Manual Uniaxial Yield Stress 0 yo a tan1C1 S Equivalent Plastic Strain p Hardening Curve Definition for the Tresca Yield Model Non Associated Mohr Coulomb Model 65 The non associated Mohr Coulomb elasto plastic model may be used to rep
364. itation as a result of the mass of the structure initial stress strain Application of initial stress strain without balancing forces will result in deformation This is used as a load type in LUSAS input output 1 0 A general term for devices that communicate with a computer or for communication via those devices integer A complete natural number having no fractional part For example 32 is an integer while 32 1 is not integration point See Gauss point interactive modal dynamics The use of results from an eigenvalue analysis to interactively calculate the frequency time response of a structure Also known as IMD interface files Used to transfer CAD data into and out of LUSAS Graphics See also DXF IGES interface stiffness parameter A property of a slideline surface which controls the penetration of contacted surfaces irregular mesh A mesh applied to a surface that has more than 4 sides irregular surface A surface defined by more than 4 lines which may only be meshed using irregular meshing 444 Index isobeam membrane A 2D membrane element which bends in plane as a beam isoflex plate A 2D thin plate which ignores through thickness shears See a so Mindlin plate isoparametric elements Finite elements formulated using an isoparametric mapping technique See a so isoparametric mapping mapping isoparametric mapping Describes the geometry in exactly the same way as the displacement field u
365. itting Lines Lines may be split at a Point or split into a number of equal or unequal divisions to form new Lines Only straight Lines and arcs can be split using these methods The splitting Lines command dialogs contain options to automatically split and delete the original Lines and to replace the split Lines with Combined Lines When splitting Lines the original Line may be deleted but only if it did not define any Surfaces or if such surfaces are modified to use the new Lines via the Use in dependent Surfaces option As a further option a combined line may be created This is useful if a regular mesh is required Any attributes assigned to a feature that is split will be automatically assigned to the new features created Line splitting commands are accessed from the Geometry gt Line gt Splitting menu item 81 Modeller Reference Manual Q At a Point Splits an existing Line into two new Lines at a selected Point on the Line Arcs can only be split using a Point on the arc Split Lines defining a Surface may be deleted and replaced by a Combined Line A splitting tolerance can be set to increase the allowable distance between a Point and the Line being split In the example here Line 3 is split at Point 5 into 2 new component Lines defining Combined Line 5 Line 3 is also replaced in the definition of Surface 1 Q In Equal Divisions Splits an existing P2 Line into a specified number of equal divisions A new Line is defined
366. ity of the incrementation scheme must be examined When beta is greater than or equal to 0 5 the solution is 305 Modeller Reference Manual unconditionally stable the Crank Nicholson Galerkin and Backward difference schemes are of this form e When beta is between the limits O and 0 5 the solution is stable provided that 2 1 7 2B max where P is the input parameter beta and Amax is the maximum eigenvalue of the system At lt e The time step used for implicit algorithms is dependent upon the number of modes that influence the response of the system Generally the major part of the response is governed by the lower modes so that ho 3X where A is the minimum eigenvalue of the system e The Galerkin scheme is recommended since it generally provides good accuracy and is the least susceptible to oscillations Nonlinear Transient Analysis For nonlinear transient analysis the backwards difference algorithm must be used beta 1 0 The backward difference algorithm is unconditionally stable and the time step length considerations are the same as for linear analyses For analyses including a phase change there is either an absorption or release of energy in order to create or break the molecular bonds This is modelled by varying the effective heat capacity in the transient analysis To do this the material property of enthalpy is introduced Enthalpy H is defined as dH dH d _c dt dp dt dt where C is the e
367. ive loading values indicate heat generation and negative values indicate heat loss The temperature dependent internal heat loading RIHG defines the rate of internal heat generation This load attribute requires a reference temperature for each set of properties Defining temperature dependent properties turns a linear thermal field problem into a nonlinear thermal problem Notes e Load curves can be used to maintain or increment the RIHG as a nonlinear analysis progresses e Automatic load incrementation under Nonlinear Control cannot be used with RIHG loading 217 Modeller Reference Manual Prescribed Temperature PDSP TPDSP Defines a prescribed temperature for an element LI The Incremental prescribed load type adds to any temperatures present from a previous increment LI The Total prescribed load type defines the total temperature at a given node at a specified increment Environmental Temperature ENVT TDET Models external fluid temperature and associated convection and radiation heat transfer coefficients If an element face does not have an environmental temperature assigned it is assumed to be perfectly insulated LI The temperature dependent environmental temperature loading TDET models properties that vary with nodal temperature This load attribute requires a reference temperature for each set of properties Q Defining temperature dependent properties will turn a linear thermal field problem into a
368. ive to the local coordinate system assigned to the feature See the Element Reference Manual for further information Resultant User Used to specify user material parameters for the user defined nonlinear resultant model See the Solver Reference Manual for further details Nonlinear User Used to specify user material parameters for the user defined nonlinear material model See the Solver Reference Manual for further details 186 Chapter 6 Joint Properties Joint material models are used in conjunction with joint elements to define the material properties for linear and nonlinear joint models See Joint and Interface Elements for information about using joints The following joint models are available Linear Joint Models LI Spring stiffness only corresponding to each local freedom These local directions are defined for each joint element in the Element Reference Manual L General Properties full joint properties of spring stiffness mass coefficient of linear expansion and damping factor Nonlinear Joint Models Q Elasto Plastic uniform tension and compression with isotropic hardening Equal tension and compression yield conditions are assumed LI Elasto Plastic General with isotropic hardening Unequal tension and compression yield conditions are assumed LI Smooth Contact with an initial gap See notes below Q Frictional Contact with an initial gap See notes below LJ Nonlinear user defined joint model S
369. l parameters and complete failure is assumed to have occurred when the fracture energy is exceeded No initial crack is inserted so the interface elements can be placed in the model at potential delamination areas where they lie dormant until failure occurs 141 Modeller Reference Manual Fracture Modes Three fracture modes exist open shear and tear orthogonal shear for 3D models The number of fracture modes corresponds to the number of dimensions of the model The diagram below illustrates the three modes Mode 3 Tear Mode 1 Open Mode 2 Shear orthogonal shear to mode 2 t Lg The interface elements are used to model delamination in an incremental nonlinear analysis These elements have no geometric properties and are assumed to have no thickness Interface elements are defined as Line or Surface mesh attributes using the Attribute gt Mesh menu item Interface Material Properties The interface material properties are defined from the Attribute gt Material gt Specialised menu item and then assigned to the same geometry as the interface mesh Strength Initiation stress Area Fracture energy G Elastic Failure Relative Opening distance displacement 142 Chapter 6 Material Parameters LI Fracture energy Measured values for each fracture mode depending on the material being used e g carbon fibre glass fibre Q Initiation Stress The tension threshold interface strength is
370. l contact force in local x direction TanForcex Yes Yes Yes Yes Yes Tangential contact force in local y direction TanForcey Yes Yes Yes Yes Yes Resultant Tangential contact force RsitTanFre Yes Yes Yes Yes Yes Contact force normal to contact surface NrmForce Yes Yes Yes Yes Yes Contact stresses Contact stress in local x direction ContStresx Yes Yes Yes Yes Contact stress in local y direction ContStresy Yes Yes Yes Yes Contact pressure normal to contact surfaceContPress Yes Yes Yes Yes Section Results Contact stiffness ContStiff Yes Yes Yes Yes Penetration normal to contact surface NrmPen Yes Yes Yes Yes In contact out of contact status ContStatus Yes Yes Yes Yes Nodal contact area ContacArea Yes Yes Yes Yes Zonal contact parameter Zone Yes Yes Yes Yes Zonal contact detection distance ZnCnDetDst Yes Yes Yes Yes Contact stiffness coefficient IntStfCoef Yes Yes Yes Yes Thermal Surface Results The results from analyses involving thermal surfaces may be processed in a similar manner as other results Extra result types are available for thermal surfaces When reading a results file a group is automatically created for every thermal surface used in the analysis These are accessed from the Group Treeview kal 364 Chapter 8 For 2D slidelines the graph wizard can be used to generate the variation of the thermal surface variables along the surface or as a history though the analysis When multiple thermal surfaces are present results for spec
371. l continue until one of the termination criteria is satisfied e In switching from manual to automatic control any loading input under the manual control is remembered and held constant while the automatic procedure is operating 288 Chapter 7 e In switching from automatic back to manual control any loading accumulated under automatic control is forgotten and must be input as a manual loadcase if required e If prescribed displacements are being used then in any switching from one type of control to another the effect of prescribed displacements will be remembered and will not need to be input again Automatic Increment Reduction Where an increment has failed to converge within the specified maximum number of iterations it will be automatically reduced and re applied This will be repeated according to values specified in the step reduction section Advanced Nonlinear Incrementation Parameters dialog until the maximum number of reductions has been tried In a final attempt to achieve a solution the load increment is then increased to try and step over a difficult point in the analysis If after this the solution has still failed to converge the solution terminated Solution Termination When using manual incrementation the solution will automatically terminate following execution of one increment With automatic incrementation the solution progresses one Nonlinear Control chapter at a time The finish of each Nonlinear Control cha
372. l left and right e If you have a 3 button wheel mouse the wheel will zoom holding the middle button will drag and holding the middle button and either of the other two buttons will rotate e To change the rotation increment visit the View tab on the Window Properties dialog right click in the current view e To change the style of the XYZ axes arrows visit the View Axes tab on the Window Properties dialog right click in the current view e To change the selection or background colours visit the General tab on the Window Properties dialog right click in the current view e Most context menu functionality for attributes is also available for groups of attributes This helps you check your model e Dragging an attribute from the treeview and dropping it on a window assigns it to anything selected in that window e Dragging and dropping layers in the layers treeview changes the order in which they are drawn This is useful if for example your solid model is eclipsing your labels e Dragging and dropping loadcases in the loadcase treeview changes the order in which they are analysed e Dragging and dropping controls attributes or groups of attributes in the loadcase treeview assigns them to a different loadcase e The Selected box in the status bar shows the number of objects are currently selected e Pressing Tab or clicking in the Selected box in the status bar cycles through all the objects which could have been selected
373. l length of a fibre Several representations of the mechanical behaviour for hyper elastic or rubber like materials can be used for practical applications Within LUSAS the usual way of defining hyper elasticity 1 e to associate the hyper elastic material to the existence of a strain energy function that represents this material is employed There are currently four rubber material models available LI Ogden LI Mooney Rivlin LI Neo Hookean Q Hencky The rubber constants used for Ogden Mooney Rivlin and Neo Hookean are obtained from experimental testing or may be estimated from a stress strain curve for the material together with a subsequent curve fitting exercise The Neo Hookean and Mooney Rivlin material models can be regarded as special cases of the more general Ogden material model In LUSAS these models can be reformulated in terms of the Ogden model The strain energy functions used in these models includes both the deviatoric and volumetric parts and are therefore suitable to analyse rubber materials where some degree of compressibility is allowed To enforce strict incompressibility where the volumetric ratio equals unity the bulk modulus tends to infinity and the resulting strain energy function only represents the deviatoric portion This is particularly useful when the material is applied in plane stress problems where full incompressibility is assumed However such an assumption cannot be used in plane strain or 3D an
374. l spring stiffness to the drilling rotation of the thick shell elements making the analysis more stable The value of the spring stiffness can be adjusted using the system parameter STFINP For problems in which geometric nonlinearity Option 87 is being used more accurate results may be obtained by switching this option off and letting LUSAS automatically establish the need for 5 or 6 degrees of freedom at a node LUSAS Solver option 278 Axisymmetry about Global X axis When selected LUSAS considers the line of axisymmetry in an analysis to be about the global X axis and not the default which is the global Y axis LUSAS Solver option 47 Lumped Mass Matrix Formulate lumped mass matrix instead of consistent mass matrix for elements LUSAS Solver option 105 Write strains to output file causes element strains to be written to the Solver output file Preserve loading whilst elements deactivated retains the loading assigned to all elements in model activated and deactivated until a subsequent load case is applied Typical usage would for example be when carrying out a staged construction analysis Self weight would be assigned to all elements activated and deactivated in the loadcase representing stage of the analysis As stage 2 and subsequent loadcases are activated the loading initially applied to elements in stage 1 would automatically be applied as the elements become active Note that when using this option no additional loadin
375. l tetrahedral elements will automatically be inserted in the appropriate positions of a transition mesh Extruded Irregular Mesh Volumes defined by sweeping an irregular Surface may be meshed with a regular Volume mesh attribute The be straight or all minor or major arcs with a common axis of rotation The side Surfaces must all be defined by four Lines so they can be meshed with a regular grid of quadrilateral faces The irregular opposite Surfaces must not share any common boundary lines therefore wedge shaped Volumes cannot be meshed as extruded irregular Volumes 126 Chapter 6 Case Study Meshing Volumes by Extruding Irregular Surfaces It is possible to mesh an irregular volume with hexahedral or pentahedral elements if the volume has been formed by sweeping an irregular surface 1 Define an irregular Surface with more than 4 sides 2 Define a Volume by sweeping the irregular surface 3 Define a Volume mesh attribute with Hexahedral or Pentahedral elements use a regular mesh with automatic divisions to ensure an equal number of divisions on the swept edges 4 Assign the Volume mesh attribute to the Volume irregular Tetrahedral Meshing Arbitrary shaped irregular Volumes defined by any number of Surfaces may be meshed with tetrahedral elements The element size may be specified on the mesh attribute taken from the defining geometry or interpolated from a background grid The mesh may be refined around small fe
376. lOtlS iiscssicisinn sts cece ninnan iinne eiaa eaaa kaaa eaae eaaa naiaiae ana 345 COMTOUNS satia S a aaa EUa aa end se eA aE a AE EE acai at 346 VOCTOTS Ai a a Caesarea DO a te alee SE 347 EO e E E A E E E a E E E E E E A E ETEA 348 Diagrams cinin a See eee a a aa a eae 349 Plotting Results for GrOUPS sirae E 350 Plotting Results for Assigned Attributes cccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeteeeeeeneeeees 351 Nonlinear Material Results Display cccccceeeseeeeeeeeeeeeeeeeeeeeeeeseeeeeeeneeeseeseeeseeeeeeeseoees 352 Results On Sections Slices Through A Model cccccssssseeseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeees 353 Displaying Beal Stresses isis nation rcttieia mie ese ectlpenieon enna e 355 Beam Stress Resultants From Beams and ShellS cccccsssseceesssneeeeeeeeeeeeeeseneeeeessnennees 358 Slideline Results ProceSsinG siiccecsccsccecssa i cicsns ch cetce cdc secs sastoes es slactenewtesesapsdcsesaseseeaeeticeteeess 361 Thermal Surtace RESUILS s sisien noana aa eaa i iaa aaaea aeai 364 Plotting Results on a Graph nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nnmnnn nnmnnn 365 Creating Animation SEQUENCES cccceeeeeeee teen ee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeas 368 Printing RESUINS ioner Oaea eaan aE aesae Ea aE aieneka 370 Printing and Saving Pictures smiir iaaa ARAA 374 Generating R POrtS osonni Feectasiebeccnetebedsce vbenesse
377. lar use in creating preliminary models for eventual staged construction uses 158 Chapter 6 Greater than constant section beam elemes tobe used along the length of the geometry to whikhthe section has been assigned a single line in this case for small variations in cross section Single geometric line attribute of 3 defined varyang sections assigned to a single selected ine Single line beam assigned a single multiple varying section line attribute for clarity beam line has been visualised at top of section Along reference path For assignment of multiple varying sections to multiple lines a reference path method is used For this option values are entered which define the distances at which a defined section is to be positioned along a set of selected lines with reference to a pre defined reference path Note that a section does not necessarily have to be defined to start at a distance of 0 A path can be specified to start at a particular distance Greater than constant section beam elemens to be used along the length of the geometry to whikhthe section has been assigned for small variaties in cross section so a minimum of 2 elements per ine are required in this case Reference path Single geometric line attribute of 3 defined van sections assigned to T selecte dines Multiple line beams assigned a single multiple varying section line attribute with reference to a path for clarity beam line has been
378. lecting will remove from the current selection e By default all items completely enclosed in a selected area will be selected By holding down the Alt key items intersecting the selection perimeter will also be selected The Alt key may be used with or independently from the Shift or Ctrl keys The Alt key can also be used with feature selection shortcuts e g Alt Shft L adds lines to the current selection e All visible items can be selected together using the Select All command which can be invoked from the Edit gt Select All menu item from the right click context menu or using the Control A keyboard shortcut e tems in the current selection may be viewed in the Browse Selection window which can be displayed from the View gt Browse Selection menu item or using a right hand click in the Selected area of the status bar at the bottom of the graphics area By means of checkboxes the selected items may be individually unselected Selection Filters k Greater control over what is selected can be achieved by changing the cursor selection filter The cursor options listed change according to the type of model in use Feature based models LI Normally the cursor will select any object i e Points he p Lines Surfaces Volumes Nodes Elements Annotation LI The selection filters allow only specific objects to be k Select Any selected 1 e with the Line filter only Lines can be ke Select Geometry selected and with the S
379. lements give correct eigenvalues for both lumped and consistent mass matrices forming the mass matrix using a shape function array QSI4 however forms the rotation terms explicitly without the use of these functions Small inaccuracies in the lumping of the mass to the rotational degrees of freedom may thus be possible for certain mesh definitions If these eigenvalues are significant the analysis should be continued using another shell element type such as QSL8 or QTS4 elemnts The magnitude of the eigenvalue shift required for an unsupported structure is usually taken as the expected fundamental eigenvalue The error norm for a given mode provides a relative measure of the accuracy of the computed modes A high error norm will provoke a warning message and signifies inaccuracy in either the eigenvalue or the eigenvector or both Warnings are not issued for computed modes which are close to zero since they may approximate rigid body modes which are exactly zero and are thus prone to incurring a large relative error For eigenvectors which are normalised to unity the largest translational component will be set to one Thus analyses containing rotational degrees of freedom for example may have eigenvectors normalised to unity that contain rotational components greater than one in magnitude If the original buckling problem is recast to a form where all eigenvalues are positive the specified load must be close to the collapse load in ord
380. licit Dynamic HX8E Stress Composite HX8L HX16L WHX20L Thermal Composite HF8 amp C HF16C HF20C Notes e No check is made in LUSAS Modeller as to whether the element type is valid for the analysis being performed however LUSAS Solver will stop the analysis if the element is unsuitable e This list is a guide as to which elements to use Not all elements are listed here e Elements in bold text are only available if your licence includes the Plus option Geometric Properties Geometric properties which have not already been defined by the feature geometry need to be specified using geometric attributes Geometric properties are element dependent and are defined for an element family such as bars beams shells joints etc Geometric attributes are defined for each feature type using the Attributes gt Geometric menu item and then assigned to the required feature or to an appropriate mesh object in a mesh only model Geometric properties can be defined for Lines Surfaces Joints Geometric Line Properties Geometric line properties such as cross sectional area second moments of area etc for bar link grillage and thin thick beam elements can be defined either by e Using the Attributes gt Geometric gt Section Library menu item to access supplied and user created items in the section library or less commonly by e Using the Attributes gt Geometric gt Line menu item to enter section properties directly on the Geometric Line d
381. lisation button 192 Chapter 6 Example Translational Fixed and Spring Example Translational Supports Supports gt This 2D structure is restrained horizontally and This 3D structure is restrained from any lateral vertically at the left edge with a single restraint in movement at the base of all legs The same points both in plane translational directions This rigidly are also sprung vertically to represent a non rigid fixes the body along the edge shown while allowing base support the rest of the model to move Example Symmetry Example Symmetry Only the right half of this structure is modelled This quarter plate membrane model uses symmetry using shell elements but the full structure is restraints to effectively model the whole plate represented by assuming symmetry at the centre Supports are positioned in order to prevent any line Symmetry assumes the same behaviour for movement at lines of symmetry both sides of the model therefore a translational restraint is applied to stop movement across the symmetry boundary and a rotational restraint is applied to force zero rotation at the boundary at Nem en 193 Modeller Reference Manual Loading Attributes Loading attributes describe the external influences to which the model is subjected Structural and Thermal loading options are provided on separate menu options according to the user interface in use A summary of the loading types is given here Q Structu
382. lisation of concrete crack patterns on a 2D model 348 Tips Diagrams Chapter 8 The percentage range sets the range of values to display starting from the maximum and or maximum values Setting this value to 100 displays all values this is useful for displaying nodal results on the screen for a subset of a model Setting this value to 0 shows only the extreme maximum and or minimum setting To prevent text labels from overlapping each other the elements on which that are drawn may be shrunk by specifying the of elements remaining on the Mesh layer properties dialog Additionally text may be given a rotation angle on the Values layer properties dialog to prevent text labels from overlapping each other Use the Show values of selection option to isolate only those values of interest or to restrict labelling on complex models to selected nodes and elements only Gauss point values display the computed values from the analysis These values may be particularly useful when examining results for nonlinear materials Unaveraged values display the computed values after they have been extrapolated to the element nodes but before they have been averaged These values may be of particular interest when examining results around discontinuities in geometry of materials Bending moment and force diagrams may be drawn for any 2 or 3 dimensional frame structure comprised of bar or beam elements All of the results for diagrams are located with
383. ll defined loadcase controls for eigenvalue fourier or nonlinear and transient analysis in readiness for a paste LI Paste Duplicates the copied loadcase and adds it to the bottom of the relevant section in the Treeview LI Delete Attribute assignments must be deassigned before a loadcase can be deleted At least one loadcase will always exist in the Treeview LJ Rename Allow the loadcase title to be modified Note that loadcases are tabulated in the order listed in the cE Treeview LI Set Active Sets the active loadcase for the current window LI Close Results File closes the open results file LI Deassign Deassigns attributes from the loadcase by choosing from a list of attribute types LI Controls Allows the analysis control for a loadcase to be defined Loadcases are solved in the order they appear in the LE Treeview from top to bottom Loadcases may be reordered using drag and drop in the iC Treeview Loadcases can only be re ordered when no results files are loaded 253 Modeller Reference Manual Setting the Active Loadcase An important concept is the active loadcase in the current window The active loadcase is a window property and is the loadcase that all results and visualisations will be generated from This speeds up the process of comparing results and visualising loads and supports as a different windows can be used for each loadcase The active loadcase is set from the Treeview using the context menu
384. load distribution Notes e While projecting the loads into the search area a check is made for multiple intersections of the load and the search area Multiple intersections indicate an ambiguity in the location of the load This ambiguity may be resolved with a more specific search area e The distribution of load to the nodes follows the shape functions of the particular element In quadratic elements this distribution can appear at first unlikely For example a unit positive load at the centre of an 8 noded quadratic element results in negative 0 25 loads at the corners and positive 0 5 loads at the mid side nodes e Search areas are automatically created and used by the prestress wizards to define the target to be loaded Discrete Load Types A discrete load consists of coordinates defining the local x y and z position and a load intensity Any Points selected when the Discrete loading dialog 1s initiated are entered as coordinates Discrete load types available are Point load Patch load and Compound load Point Load Defines a general set of discrete loads in 3D space Each individual load can have a separate load value Point loads can be defined via Arbitrary input or by specifying a Grid input This example uses 16 distinct load values The loads are applied to the model as distinct loads or ty t x 202 Chapter 6 Patch Load The number of coordinates given dictates the shape of the patch
385. loadcase determines the time over which the load is applied The magnitude of the applied load is computed from the time dependent function defined within each load curve Any number of loadcases and load curves may be specified within a single analysis Each load curve is assumed to begin at the start of the analysis t 0 If the input values stat from t n the load curve is assumed to be zero when t lt n Results may be manipulated using combinations and envelopes fatigue loadcases and IMD loadcases all of which are added to the Treeview Creating Loadcases New loadcases may be added to the LE Treeview in the following ways e By creating a Structural Thermal Envelope Combination Fatigue or IMDPlus loadcase from the Utilities menu e By entering a loadcase name when a load attribute is assigned to a feature on a model e By right clicking on a Loadcases Structural or Thermal entry in the LE Treeview and selecting the New loadcase menu item e By copying and pasting existing loadcases in the LE Treeview Adding Gravity Loading to a Structural Loadcase As an alternative to defining gravity by specifying and assigning a constant body force to all features on a model gravity can also be added to a model as a property of a structural loadcase This can be done in three ways 202 Chapter 6 e By selecting the the Automatically add gravity to this loadcase option on the dialog that is displayed when defining a new loadcase or di
386. loadcase that provides the l amp 2 16 fn results for the current window In this way a single 5 frame_2d mdl A H 4 Loadcases window is used to plot results from a single loadcase Structural and multiple windows can be used to compare results pem i from different loadcases o 4 Loading Rename 1 Se Fla 2 Loadcase MEETS Loading Close Results File 2 Sy X AD 3 Combination 1 aaan Combination anc Controls IE Setting the Active Fibre Location For plotting diagram results on bars and beams only le amp Q 2 IB the active fibre location for which results will be frame_2d md plotted must be chosen Fibre locations available for iie es Haah z these elements can be seen and can be set active in the Geometric 3 R N 3 Line 2 Treeview Fibre locations can visualised by H 2 127x76x13kq UB major y stanchi double clicking on the Geometric Line name and z v Set Fibre Active selecting the Visualise button on the dialog presented Fibre Zoo gt me Fibre l4 Setting the Fibre Active shows results for just that LA 2 70 70K6 EA major y tof member fibre Setting the Name Active shows results for all Surface 1 1 Unit Thickness 5 4 Material 1 fe a eee oe F b similarly named fibres throughout the model Setting the Active Composite Layer With composites analysis in order to
387. loading in nonlinear transient and Fourier analyses For example in a transient problem the loading changes with time in a nonlinear problem the loading level varies with load increment and in a Fourier analysis the loading varies with angle Load curves are used to simplify the input of load data in situations where the variation of load is known with respect to a certain parameter An example of this is the dynamic response of a pipe to an increase of pressure over a given period The load curve factor would then consist of the variation of pressure with time Creating Load Curve Entries New load curve entries may be added to the Treeview in the following ways e By creating a load curve from the Utilities menu 204 Chapter 6 e By right clicking on a Loadcases Structural or Thermal entry in the Treeview and selecting the New load curve menu item e By copying and pasting an existing load curve in the Treeview Defining Load Curves A load curve is defined either using a user defined time vs factor curve a standard sine cosine or square wave curve or a variation Q Time vs Factor specify values for both in a table on the load curve dialog LI Sine cosine square wave input values for peak amplitude frequency and phase angle must be defined along with activation and termination points Q Variation A line interpolation variation may be defined from the Utilities gt Variation gt Line menu item The depe
388. loads the output file created during the solution process Notes e During the tabulation process progress will be reported to the Text Window If problems are encountered warnings and or error messages will be displayed in the same window Such warnings and errors can be caused by inconsistencies in the model data which may produce erroneous analysis data files These errors should be acted on before continuing with an analysis e LUSAS is configured to run the majority of analyses without the need to adjust the system parameters In some circumstances however it may be necessary to adjust one or more of these parameters System parameters may be modified from within the File gt Model Properties using the System Variables tab Modified parameters will be tabulated ina SYSTEM chapter at the start of the LUSAS Solver data file Advanced Solution Options The analysis is controlled from the Advanced Solution Options dialog activated using the Advanced button 51 Modeller Reference Manual Datafile Type Q General analysis should be used for all analysis types except influence line analyses default LI Influence Lines produces a data file as above with additional files describing influence line and search area information Type Q Structural Carries out a structural analysis Q Thermal Carries out a thermal field analysis LJ Coupled Carries out a coupled analysis Controlling Content of LUSAS Solver Output File By default
389. lowing a slideline analysis 33 Modeller Reference Manual Defining Groups First select the model features to be grouped together and then select either the LJ icon on the main toolbar or use the Geometry gt Group gt New Group menu item All current group definitions are listed in the Group panel of the L Treeview Manipulation of Groups can be carried out using the context menu of the Group panel and or using the sub menu entries under the main Geometry gt Group menu item Naming Groups Groups can be given a meaningful name at the time they are defined They may later be renamed in the LH Treeview or from the group properties accessed from the context menu Manipulating Groups Groups are listed in the LH Treeview From a group s context menu the following commands will act on that group in the current window Q Visible Makes all members of the group visible l amp lf IF Concrete_Dam mdl Stage 1 K Stage 2 R Stage 3 Visible A Slices Invisible k Slice Set as Only Visible A Slice Advanced Visibility R Slice Results Plots gt KA Slice Current Group Q Invisible Makes all members of the group invisible LI Set as Only Visible Makes the whole model invisible and then sets all the members of the group to be visible Q Advanced Visibility Enables the visibility of the higher and lower order features of the members of a group to be manipulated Rename Delete LI Results Plots permi
390. lts LI Solver System Variables General Title Brief description of the current model as entered in the New Model startup dialog User Interface Enables the user interface to be simplified by specifying the type of analysis model being generated Options dependent upon licence key is use are Coupled Structural Thermal Associated main menu items are removed if licence key does not include a thermal option Note that changing an interface type will not remove any properties created when using the previous interface Auto backup Saves the model automatically as it is being developed or modified Precision shown in dialogs Controls the number of significant figures or decimal places displayed in the dialogs 18 Chapter 2 Pens Sets the Pens that are used to draw Points Lines Surfaces and Volumes Click on the Choose Pen button to use a different pen or to modify the Pen Library Changing a Pen allocation can be applied to existing features and or new features using the two check boxes Units Specifies the modelling units Notes Notes relating to a model can be typed in the Notes panel of the Model Properties dialog and stored with the model Geometry The method by which the geometry is displayed is controlled using the Geometry drawing layer Q Merge Options e Action controls the criteria that must be satisfied before features sharing a common definition will be merged e New geometry unmergable sets the merg
391. lts from each of the above criteria can be displayed as 333 Modeller Reference Manual Design Factor Calculation Failure Failure Yield Index actual allowable gt 1 Factored Failure Yield Index DF actual allowable gt 1 Factor of Safety allowable actual lt DF Reserve Factor RF allowable DF actual lt 1 Margin of Safety RF 1 lt 0 where DF Design factor defined with material strength allowable allowable stress actual actual stress See the Theory Manual for further information Composite Layers When viewing composite results it is often useful to change the results orientation to material directions to view the results in fibre and off fibre directions See Local and Global Results for more details Note A layer of a solid composite element is treated like a shell Thus top middle or bottom stresses can be obtained Composite Failure Criteria Composite failure criteria is defined as an attribute from the Composite gt Composite Failure menu item It provides a means of assessing the reserve strength capacity of composite components without carrying out a full nonlinear analysis To use this facility the results file must be loaded on top of the model file LJ Longitudinal and transverse tensile and compressive strengths must be defined along with a shear strength which cannot be zero LI Interaction type can be set to use Default User or Cowin values Once created the Composite Failure attribute should be
392. lues for draping over model surfaces Layup data can also be imported from a FiberSIM XML file also for draping over selected model surfaces Composite Layup Methods The following methods are available as a result of selecting the Attributes gt Composite menu item Q Solids and Shells Q Draped Solids and Shells LJ FiberSIM Solids and Shells LJ Simulayt Solids and Shells 241 Modeller Reference Manual Solids and Shells This method allows a manual definition of the composite lay up where orientations and thicknesses for the plies can be specified by stacking layers of differing materials at various angles and thickness The orientation angles can be applied with respect to the local element X axis in the x y plane or with respect to the x axis of a predefined Cartesian set The z axis defines the direction of the lay up with ply 1 located at the bottom of the stack The lamina thickness specified depends upon the element types used Notes e Only orthotropic plane stress for semi loof shell or orthotropic solid for thick shell materials can be used for structural shell composite lay ups Structural solid composites models must use the orthotropic solid material model and thermal solid composites models must use the orthotropic solid field material model Isotropic materials may be used within any composite lay up e For shell elements an appropriate plane stress nonlinear material model may be used whilst for solid elements
393. m the main menu pressing the right hand mouse button with an object selected in the Graphics Window usually displays a context menu which provides access to relevant operations In addition most items in the various Treeview panels also have a context menu which provides access to additional functionality such as editing of data control of visibility visualisation of assignments and selective control of results plotting on selected attributes Properties General information relating to a model is presented in property dialogs Properties may relate to the whole model or the current window or a single geometric feature in fact most objects have properties To view an object s properties select it press the right mouse button then choose Properties from the context menu Status Bar The Status Bar displays progress messages and help text during a modelling session the model units the current cursor position in model units if the model is displayed in an 10 Chapter 2 orthogonal plane and the item or number of items in the current selection The View gt Status Bar menu item may be used to hide or show the Status Bar Text Window By default the Text Window appears at the bottom of the graphics window just above the Status Bar The size of the Text Window may be resized using the cursor and it may be undocked or hidden from view The Text Window displays messages and warnings during a modelling session The View gt Text Outp
394. m which it is created e When a report is first loaded into the report viewer the Page Down key will not work until the view has acquired focus Simply click anywhere in the view to set the focus e When saving to disk the default export directory is a temporary directory specified by the report viewing software that is used Browse to your LUSAS project directory if you wish to save your report file with your model The number of pages to be exported or saved can be specified Creating and Viewing Sub Reports When viewing a report selected sections of data may be viewed in a sub report This can be particularly useful when wanting to export selected data to another application as for instance when exporting report results data to a spreadsheet It also provides an easy way of visually printing selected pages of a main report 383 Modeller Reference Manual Sle ro 28 3d S po z m E Preview frame malbsis 2 Tuesday September 29 2009 Date saved 29 Sep 09 10 42 20 Results Chapter 1 Displacement Loadcase 1 Title Loadcase 1 Line 1 Node Dx DY RSLT THE 0 0 0 0 0 0 0 0 29 5929E 6 6 5848E 6 30 3167E 6 92 5111E 6 2 DX DY RSLT THE 0 445019E 18 0 263404E 3 0 263404E 3 28 9669E 21 0 445298E 18 0 261537E 3 0 261587E 3 31 7524E 21 e To create a sub report from a section of a normal report double click on the main body of the data where you wish a sub report to be generated or double click on a feature
395. mart combinations For the purposes of these examples the results at a single node are going to be considered LI Case 1 Considers a node where long term load effects are all negative LI Case 2 Considers a node where short term load effects are of mixed sign LI Case 3 Considers a node where short term load effects are of mixed sign with the Loadcases to consider set to four LI Case 4 Considers a node where short term load effects are of mixed sign with the Loadcases to consider set to four and the Variable loadcases set to four LI Case 5 Considers a node where short term load effects are of mixed sign with the Loadcases to consider set to four and the Variable loadcases set to one Smart Combination Case 1 Consider a node where long term load effects are all negative In this instance the permanent and variable load factors are considered and will be added together based on the nodal result being adverse Smart combination Max will assemble results from the loadcases using just the permanent factors given for negative load effects and using permanent variable factors for positive load effects 389 Modeller Reference Manual Factor used for Nodal Permanent Variable maximum Factored nodal Loadcase result factor factor combination results Dead load 20 1 0 0 15 1 0 20 x 1 0 20 Deck surfacing 10 1 0 0 75 1 0 10 x 1 0 10 Superimposed 15 1 0 0 2 1 0 15 x 1 0 15 load
396. mat The documentation includes LI Installation Guide LI Getting Started Guide LI Modeller Reference Manual Q Examples Manual Q Application Examples Manual Bridge Civil amp Structural Q Application Manual Bridge Civil amp Structural LI Autoloader Reference Manual LJ IMDPlus User Manual Q Rail Track Analysis User Manual LI Element Reference Manual LI Solver Reference Manual Modeller Reference Manual Q Theory Manual Volume 1 and 2 UL Verification Manual LJ CAD Toolkit User Manual LJ LUSAS Programmable Interface LPI LI Glossary Installation Guide e Details of installing LUSAS software for various licensing options e Available in PDF and printed form Getting Started Guide e Contains a brief overview of LUSAS e Available in PDF and printed form Modeller Reference Manual e Provides detailed reference material for modelling and results viewing with LUSAS Modeller e Provided in on line help format and also available in PDF and printed form Examples Manual e Contains general worked examples to help you get up to speed with modelling analysis and viewing of results for a range of different analysis types e Available in PDF and printed form Application Examples Manual Bridge Civil amp Structural e Contains application specific worked examples to help you get up to speed with modelling analysis and viewing of results for a range of different analysis types e Available in PDF and pr
397. mation such as images and text may be added to a report in 376 Chapter 8 the form of chapters Each chapter represents one single aspect of the model Multiple chapters may be added and re ordered as necessary in the Report Treeview Chapters are added to a report by selecting the Add Chapter menu item from the Report name context menu accessed by right clicking the mouse button The following chapters can be added LL Model Properties L Loadcase Basic Combination results L Envelope Smart Combination results L Eigenvalue results L User Content Add or Edit a Model Properties Chapter Model properties Loadcase Basic combination results Eigenvalue results User content Iv All Geometry Attributes Loadsets Geometry E A Attributes ElV Loadsets Points M Mesh V Loadcase Lines M Geometric MIMD Loadcase Z Material M Supports V Loading Significant figures Report on Full model C DnA aS le Cancel Help The Model Properties tab of the Chapters dialog allows model geometry attributes and loadcase IMD loadcase information to be added to the report via the use of tick boxes The Report on button displays a dialog which controls the scope of the chapters to be created By default the whole model is selected but a report could also created for just the visible model or for a specified group It is also possible to control the number of significant fig
398. mbering uses the next highest available number for Lines or Combined Lines e Mesh attributes may not be assigned to Combined Lines but must be assigned to the Lines defining the Combined Line e Using Combined Lines in the definition of Surfaces provides an additional means of producing transition meshes 83 Modeller Reference Manual Case Study Using Combined Lines Combined lines may be used in a surface definition in order to use a regular mesh Define a Surface using the New Surface button oj and enter the coordinates L 0 0 0 100 0 0 120 20 0 100 100 0 and 0 100 0 2 Define a Line mesh attribute using Attributes gt Mesh gt Line with of element type None with mesh divisions of 1 and assign it to the shorter Line on the left hand side of the surface 3 Define a Line mesh attribute using Attributes gt Mesh gt Line with of element type None with mesh divisions of 3 and assign it to the longer Line on the left hand side of the surface 4 Define a Surface mesh attribute using using Attributes gt Mesh gt Surface with Plane Stress Quadrilateral Linear elements and assign it to the surface This will automatically select an irregular mesh for a five sided Surface as shown below 5 Now define a Combined Line by selecting the Lines on the left hand side of the model and press the El button from the Line menu item 6 Since the Surface definition has been altered the Surface will be remeshed A regular me
399. mbrane BSL4 Joint no rotational stiffness BXM2 BXM3 JNT4 Joint for beams JNT3 JSH4 Joint for grillages JPH3 Joint for axisymmetric solids JF3 Joint for axisymmetric shells JAX3 Thermal bar JXS3 BFS2 Axisymmetric thermal membrane BFD2 BFD3 BFS3 Thermal link BFX2 BFX3 LFS2 Interface LFD2 IPN6 Notes e Quadratic elements are curved with a mid side node e For some beam elements rotational freedoms at the ends of a Line can be made free to rotate by using an element with moment release end conditions e No check is made in LUSAS Modeller as to whether the element type is valid for the analysis being performed however LUSAS Solver will stop the analysis if the element is unsuitable e This list is a guide as to which elements to use Not all elements are listed here See the Element Reference Manual for full details of all elements e Elements in bold text are only available if your licence includes the Plus option 145 Modeller Reference Manual Surface Element Selection The following table lists the elements available for surface meshing by type and by name The first column matches the option list in the Surface mesh dialog box Generic Element Types Plane stress Plane strain Axisymmetric solid Thin plate Thick plateThin shell Thick shell Membrane Fourier Plane field thermal Axisymmetric solid field Explicit dynamic plane stress Explicit dynamic plan
400. ment Diagram e a e e a a Minimum Enveloped Bending Moment Diagram eee Wood Armer Reinforcement The Wood Armer facility allows reinforced concrete slabs to be designed to resist a combination of moments Mx My and a twisting moment Mxy using orthogonal or skew reinforcement Following a linear elastic analysis the Wood Armer facility determines the design moments Mx T My T Mx B My B The procedure was originally developed for a moment field obtained from a plate analysis but may also be applied to shell or grillage analyses For a slab modelled as a shell subject to a moment field Mx My Mxy and a stress field Nx Ny Nxy the Wood Armer principles are extended using the Clark Neilsen calculation The final output Nx T Nx B Ny T Ny B Fe T and Fce B incorporates both bending and in plane load effects In order to obtain equivalent in plane forces from the applied moments it is necessary to establish the distances between the centroid of the reinforcement layers and the middle surface of the slab This is calculated using the thickness of the shell elements entered in the geometric properties and the distance to the reinforcement centroid from the face of the slab entered in the Wood Armer dialog An approximate approach is also available for grillage elements whereby bending and twisting moments are converted into equivalent plate moments so that the Wood Armer equations can then be used An extra geom
401. merge commands are available from the Geometry menu under each feature type L Merge Merges all mergable features currently selected subject to the current merge characteristics and tolerance Lower order features must be merged first for example two Lines cannot be merged until the Points defining the Lines are themselves merged When selected at the same time LUSAS merges lower order features before higher order features Q Make Mergable Unmergable Sets the merge status of selected features Merging can happen unintentionally in the normal course of events when additional features are defined in the same position as existing features Using this command it is possible to prevent two coincident features being merged by making one of the features unmergable The merge status of an individual feature may be viewed and altered by displaying the properties of the selected feature right click button on the Hierarchy tab Q Unmerge Duplicates or retracts selected features into higher order features which reference them in their definition When a feature is unmerged from its higher order features any new features defined are automatically set to be unmergable Merge Options Several merge settings can be set from the Geometry tab on the Model Properties dialog 103 Modeller Reference Manual Q Ask for Confirmation Configures Modeller to prompt for confirmation before selected features are merged Confirmation tab LI Merge Toler
402. mesh divisions on opposite sides of the Surface must match If they do not match transition patterns will be used if allowed in the mesh attribute definition The examples shown here mesh triangular and quadrilateral Surfaces using both triangular and quadrilateral elements LI The Surface mesh may be graded using mesh spacing parameters in None element Line meshes assigned to the boundary Lines In the examples shown here mesh spacing has been used to bias the elements into the apex of the triangle or one corner of the rectangle irregular Surface Meshing Irregular meshing is used to generate elements on any arbitrary Surface LI Element Size specifying the required approximate element edge length Meshing Volumes Volumes are meshed using regular mesh patterns transition mesh patterns or irregular tetrahedral meshing 124 Chapter 6 Tetrahedral Volumes Tetrahedral Elements ________Pentahedral Tetrahedral Elements Pentahedral Volumes Pentahedral Elements Hexahedral Pentahedral Elements Hexahedral Volumes Pentahedral Elements Hexahedral Elements Hexahedral Pentahedral Elements The mesh density for volumes is taken from the boundary surface mesh density 125 Modeller Reference Manual Regular Volume Meshing In order to generate a regular mesh pattern the number of mesh divisions on opposite faces of the volume must match If they do not match then transition patterns will be used Pentahedra
403. metric data at all The number and shapes of the elements of a mesh only model are fixed The type of element may be changed and this is done by use of the Change Element Type option on the context menu on the element group name In doing so the number of nodes defining the element topology may be reduced but not increased For instance an 8 noded brick elements may be defined for use on previously defined 20 noded brick elements See Changing Geometry Element Orientation if element axes need to be changed Mesh Types Various mesh patterns can be generated LJ Regular Only used on regular Surfaces and Volumes Any element shape may be selected for regular meshing Options exist to automatically allow transition or irregular meshes to be generated when regular meshing is not possible Q Irregular Used for Surfaces and Volumes An irregular Surface mesh may consist of triangular or quadrilateral elements A irregular Volume mesh must consist of tetrahedral elements Irregular Volume meshes will only be generated if specified as acceptable in the mesh attribute LI Interface Meshes Only applicable to joint and interface elements 120 Chapter 6 Mesh Visualisation The Mesh layer properties control how the mesh is displayed in the current Window The same controls are available for the undeformed mesh and the deformed mesh but since they are different layers in the E Treeview different properties can be applied to each layer Style L
404. metry may be different In the example shown here Master and Slave Surfaces define start and finish positions of repeating sections Meshes on Master and Slave need not match Master 232 Chapter 6 Tied Mesh LI Specified Constraint Tied meshes may be used to force two sets of assigned features to move together in a similar manner to tied slidelines The meshes are tied along Master and Slave Lines to restrict relative movement The mesh on the two sets of features need not match A search direction vector is defined to limit the mesh to which it is tied A vector defines the direction in which the constraint is applied LJ Normal Constraint Meshes tied along Master and Slave Slave Lines to restrict relative movement The underlying nodes maintain their original relative positions under loading Meshes on Master Slave need not match This form of tied mesh constraint uses a Search direction normal to the Master Slave surfaces to detect the mesh to which it is tied Master Case Study Using Constraint Equations Differing meshes may be constrained to displace together in a similar way to a tied slideline 1 Define two Surfaces separated by a small gap using Geometry gt Surface gt Coordinates 2 Mesh the Surfaces with Linear Plane Strain elements using different mesh spacing on each Surface using the Attributes gt Mesh gt Surface menu item 3 Define and assign a valid Material
405. miser options tab and is only invoked when the standard frontal solver is chosen Selecting the Frontal Optimiser Front optimisation is only required when using the standard frontal solver The frontwidth of the problem may be reduced by optimising the order in which the elements are presented Optimising methods supported are LI Standard uses the standard LUSAS optimiser Q Akhras Dhatt uses the Akhras Dhatt optimiser A number of iterations must be specified for this optimiser The iterations are used to find the best starting point in the structure for the optimisation The higher the number of iterations the better the chance of locating the optimal starting point but the longer the optimisation process takes Q Cuthill McKee optimises the solution based on the Cutill McKee optimiser This algorithm bases its optimisation on a specified parameter Options are maximum bandwidth RMS wavefront bandwidth and profile This optimiser was originally written by E H Cuthill and J M McKee and was improved by G C Everstine Q Sloan uses the Sloan optimiser default If no optimiser is specified then the Sloan optimiser is used by default Choosing the Solver Direct e g frontal solvers are more robust than iterative solvers and are applicable to all types of analysis Direct solvers should always be used for very ill conditioned problems since the time taken to obtain a solution is independent of the problem conditioning Iterative
406. mmand The format is resultfile D model mode2 mode aTmode blincrement etc Q Additional system parameters are required to deal with problems encountered when reading the neutral file into LMS These variables should be set as shown below in the Modeller start up file The variables are defined as follows Q LMSTKV when set forces the THICKV element property keyword to accept the NO_DEF purpose code to describe the property type instead of MEMBRANE PLANESTRAIN SHELL PLATE and SHEAR This is due to an error in the LMS parser LMSTKV should be set to 1 to have NO_DEF output to the neutral file LMSTKYV should be unset to have normal codes output to the neutral file The default setting is 0 LI LMSDMP forces the export routines to only output SPRING and MASS elements and properties for joints instead of SPRING MASS and DAMPER elements and properties This is to work around a limitation in the LMS parser which will not interpret the DAMP or DAMPER keywords LMSDMIP should be set to 3 to have 3 properties elements per joint output LMSDMIP should not be set to have 2 properties elements per joint output The default setting of LMSDMP is 2 2 properties elements per joint LJ LMSPRC allows the user to specify single or double precision real number output in the neutral file Using this parameter can reduce the size of the neutral file The differences between the two types of precision is as follows Single precision n nnnnnnE ee Dou
407. mponent Only those components applicable for the elements used in the model will be displayed The entities and results types available when applicable are None LI Eigenvalues eigenvalue frequency and error norm Q Participation Factors participation factors in X Y and Z directions LI Mass participation factors mass participation factors in X Y and Z directions Q Sum of mass participation factors sum of mass participation factors in X Y and Z directions This enables the of active mass in each direction to be determined as the sum of the mass participation factors in each direction should be unity Displacement Residual Reaction Reaction Stress Loading Potential Flux Gradient L Component component results in tabular format Q Summary maximum and minimum visible values and their position on the model Stress Strain LJ Component component results in tabular format Q Summary maximum and minimum visible values and their position on the model Q Principal principal values in tabular format Q Wood Armer components Wood Armer reinforcement moments and forces in tabular format LJ Wood Armer assessment Wood Armer reinforcement moments and forces in tabular format LI Fatigue or Damage Results fatigue Log Life and damage results in tabular format LI Energy strain energy and plastic work results Q State variables extra nonlinear material parameters Slideline results Q Component
408. n Line defined by a Line and Surface map LI Intersection defined by two Surface maps LI Isoparametric Line geometry is defined from the Geometry gt Line menu item 76 General Line Definition Chapter 4 Q Coordinates Defines a Line by entering the X Y and Z coordinates Entering more than two coordinates will define linked Lines If a non Cartesian local coordinate system is in use the coordinates are specified in the coordinate system of that local coordinate LI Cursor Allows definition of a series of straight Lines on the screen with the cursor The Lines can snap to a grid in the XY YZ or XZ plane The out of plane ordinate can be specified as non zero if desired LI PointsDefines a Line from selected Points A dialog is displayed to specify the Line type as either Straight Line s Arc or Spline LI Tangent Point to Line Defines a Line between a selected Point and the tangent to a selected Arc An error will occur if no tangent is possible In this example Line 2 is created by specifying Line 1 and Point 4 Point 5 is automatically created LI Line between Arcs Defines a Line which is tangent to two coplanar Arcs The new Line can be defined as an inside or outside tangent Options are available to split the Arcs at the new Points and then delete the original Arcs LI By Sweeping Defines a Line by sweeping a Point through a transformation translation rotation mirror or scale Multiple transformations can b
409. n each increment Notes e For linear analyses with multiple loadcases an automatic restraint is only assigned if the prescribed displacement is applied in the first loadcase If a prescribed displacement is not assigned in the first loadcase but is assigned in subsequent loadcases a restraint must be assigned manually e Total and incremental prescribed displacements should not be used in the same analysis e tis recommended that total prescribed displacements are used with load curves e Prescribed rotations should be specified in radians Prescribed Velocity and Acceleration In dynamic analyses velocities and accelerations may be defined for any nodal variable These values can be used to specify an initial starting condition or prescribed for the whole analysis Q A prescribed or initial Velocity defines a velocity loading in global or transformed directions LJ A prescribed or initial Acceleration defines an acceleration loading in global or transformed directions If acceleration loads are required the density must be specified in the material properties Initial accelerations are only valid for implicit dynamic analyses 200 Chapter 6 Notes e Ifthe values are to be prescribed throughout the analysis load curves must be used see Load Curve Definition e Initial velocities and accelerations should only be applied to the first loadcase e In general load curves should be used to prescribe velocities an
410. n may be selected the default being relative Notes e Displacement and velocity excitations are not allowed for modal response calculations in the time domain 337 Modeller Reference Manual e Support Motion excitation may be the most appropriate if all the supports move together e Large Mass point displacement velocity or acceleration excitation may be the most appropriate if the supports do not move together e For Point Displacement Velocity and Acceleration excitation the displacement response is absolute and not relative to supports e When using Support Motion excitation in the frequency domain the displacement response may be specified as relative or absolute If absolute is chosen then the motion of the support is added to the structural motion to give motion with respect to ground This is useful for comparison with measured data The Large Mass Method Interactive Modal Dynamics frequently employs an analysis technique referred to as the Large Mass Method The reason for this is to earth the structure via a moveable object rather than a strict support to ground This allows subsequent application of a force to the mass in effect applying an acceleration to the structure The size of this mass should be sufficient to ensure mass dominated local response so that the motion of the point is described by Newton s Second Law i e F ma A mass of 1E6 kg works well for most structures Unduly large values may cause
411. n of plastic work that is converted into heat energy Only applicable to temperature dependent materials and coupled analyses where the heat produced due to the rate of generation of plastic work is of interest The value should be between 0 and 1 Hardening Properties There are three methods for defining nonlinear hardening Hardening curves can be defined in terms of either the hardening gradient the plastic strain or the total strain as follows LI Hardening gradient vs Effective plastic strain Requires specification of gradient and limiting strain values for successive straight line approximations to the stress vs effective plastic strain curve In this case hardening gradient data will be input as C1 ep1 C2 ep2 for each straight line segment LUSAS extrapolates the curve past the last specified point Stress Gradient Cl sl sy epl ss Gradient C2 s2 s1 ep2 ep1 Effective Plastic Strain ep1 ep2 167 Modeller Reference Manual Q Uniaxial yield stress vs Effective plastic strain Requires input of coordinates at the ends of straight line approximations to the uniaxial yield stress vs effective plastic strain curve For the curve shown here the plastic properties will contain the yield stress sy and the hardening data will be input as s1 ep1 s2 ep2 etc LUSAS extrapolates the curve past the last specified point Elastic Plastic Stress Curve Extrapolation ep3 Effective Modulus Plastic St
412. n on opposite sides of the Surface see the following example and use the Line order in the Surface definition on which to base the variation direction Individual Line directions have no effect on variation directions LI Surface boundary interpolation using three Line interpolation variations Same Variation As First Line 1 A discontinuous Line interpolation 1 is specified for first and third Lines using a Line by unequal distance variation Line Interpolation Constant 2 Value 3 Note that the Line axes drawn here dictate the variation directions and the line Line ae l A f Interpolatio Line Interpolation directions on opposite sides of a surface oo o gt eines r F alues must match as shown Variations are 4 5 3 2 4 3 applied in a positive surface normal direction The second and fourth Lines in the Surface definition use constant interpolation variations The variation sense is denoted by double and single arrows shown on boundary Lines The variation along the local x axis signified by the double arrow is specified first The Surface variation in this case is 1 3 1 2 266 Chapter 6 Surface Function Variations A Surface function variation consists of a single Variation function in terms of the parametric coordinates of Max 4 10 u the Surface u and v The value of the variation at any point on the Surface is given by finding the parametric co
413. n the type of coordinate systems in use Definitions are 3 p given in the tables below N Field Variation N in Global Axis System In this example a field expression referring to the global axis coordinates XY is also used with a local coordinate axis set indicated by xy to create a variation relative to a rotated system Cylindrical and spherical axis sets can also be used 260 Variables Cartesian global local X X ordinate y Y ordinate Z Z ordinate Operators E e x A Functions Trigonometric functions Sine of angle Cosine of angle Tangent of angle Arcsine of a Arccosine of a Arctangent of a Arctangent of the specified x and y coordinates hyperbolic sine of a hyperbolic cosine of a hyperbolic tangent of a Z Cylindrical local r thetaz Radians sin angle cos angle tan angle asin a acos a atan a atan2 x y sinh a cosh a tanh a Chapter 6 Z Spherical local Radial distance r Radial distance Angle about axis of cylinder thetaz Angle about z axis Distance along cylinder longitudinal axis 261 thetac Second angle Degrees sind angle cosd angle tand angle asind a acosd a atand a Modeller Reference Manual Function return value e raised to the power of a The constant e equals 2 71828182845904 the base of the natural exp a logarithm natural logarithm of a log a logarithm of a to base 10 log10 a square root of a sqrt a a rounde
414. nce from the start of the line to the start of the distributed loading and the distance from the start of the line to the end of the distributed loading are defined along with the load component and the start and end load values Several distributed loads may be defined in one load attribute if required Start Distance lt See the Element Reference Manual for details of internal beam loading ELDS and elements which support this loading type Initial Velocity Initial Acceleration VELO ACCE In dynamic analyses velocities or accelerations at a nodal variable can be defined These values can be used to specify an initial starting condition or they may be prescribed for the whole analysis If values are to be prescribed throughout the analysis load curves must be used and the appropriate freedoms must be restrained 199 Modeller Reference Manual Prescribed Loads For information on which load types can be applied to which element types see the LUSAS Element Library Prescribed Displacement A Prescribed Displacement defines a nodal movement by either a Total or Incremental prescribed distance in global or transformed axis directions Freedoms which are assigned a non zero prescribed value will automatically be restrained This example shows two methods of applying prescribed displacement Incremental loading adds displacements to a previous increment whereas total requires the full displacement to be specified o
415. nd constrained solution methods Constrained Solution Methods Arc Length Constrained methods differ from constant level methods in that the load level is not required to be constant within an increment In fact the load and displacement levels are constrained to follow some pre defined path In LUSAS two forms of arc length method have been implemented Q Crisfields modified arc length procedure in which the solution is constrained to lie on a spherical surface defined in displacement space For the one degree of freedom case this becomes a circular arc Q Rheinboldts arc length algorithm which constrains the largest displacement increment as defined by the predictor to remain constant for that particular increment The use of the arc length method has the following advantages over constant load level methods e Improved convergence characteristics e Ability to detect and negotiate limit points 286 Chapter 7 In LUSAS control of arc length solution procedures is via the Incrementation section of the Nonlinear Control properties If required the solution may be started under constant load control and automatically switched to arc length control based on a specified value of the current stiffness parameter defined as the scaled inner product of displacements and loads The required stiffness parameter for automatic conversion to arc length control is input in the Incrementation section of Nonlinear Control properties Wher
416. nd layer soil elements deactivated Tunnel Excavation Stage 5 Final central soil column removed a Soir a T 7 aaa OY a f Gem AL ee ee E tun Ta See EE EETA ee age SS ee aN iro a a a aeon Tr T oh oA l oo Ai 4A T T en f ieee Y m H A j m ee f f H Using Birth and Death Attributes gt excavated Chapter 6 Tunnel Excavation Stage 4 Supporting soil pillar removed and top lining activated Lining construction N Soil A excavated UHE Activate and deactivate attributes are defined from the Attributes menu The attributes are assigned on a feature basis to control the history of the underlying elements throughout the analysis The loadcase is specified during assignment to indicate at what point the elements are added or removed Notes e Elements cannot be activated and deactivated in the following circumstances e Explicit dynamics analyses 225 Modeller Reference Manual e Fourier analyses e When using updated Lagrangian or Eulerian geometric nonlinearity e When they are adjacent to slidelines e Activation and deactivation can only be carried out within a nonlinear analysis e Deactivation and activation can take place over several increments if convergence difficulties are encountered e Deactivated elements remain in the solution but with a scaled down stiffness so that they have little effect on
417. ndard Newton Raphson procedure each iterative calculation is always based upon the current tangent stiffness For finite element analysis this involves the formation and factorisation of the tangent stiffness matrix at the start of each iteration Although the standard Newton Raphson method generally converges rapidly the continual manipulation of the stiffness matrix is often expensive The need for a robust yet inexpensive procedure therefore leads to the development of the family of modified Newton Raphson methods Iterative Acceleration Line Searches A slow convergence rate may be significantly improved by employing an iterative acceleration technique In cases of severe and often localised nonlinearity encountered typically in materially nonlinear or contact problems some form of acceleration may be a prerequisite to convergence In LUSAS iterative acceleration may be performed by applying line searches In essence the line search procedure involves extra optimisation iterations in which the potential energy associated with the residual forces at each iterative step are minimised Line search application is controlled via parameters on the Iteration section of the Nonlinear Control properties The selection of line search parameters is problem dependent and largely a matter of experience However a maximum of 3 to 5 line search iterations with a tolerance of 0 3 to 0 8 is usually sufficient the closer the tolerance is to unity th
418. ndent variable in the variation will represent time or increment number depending on the type of analysis The value of the variation will be the factor by which to scale the values in the assigned loading attribute Load curves scale all loads assigned to them Therefore if loads have a different variation of load factor with time several load curves should be used Manipulating Load Curves General load curve editing commands are available from the context menu that is activated by right clicking on a load curve in the Treeview The following commands are available LI Copy Copies the selected load curve including all defined load curve data in readiness for a paste LI Paste Duplicates the copied load curve and adds it beneath any current load curves in the Treeview LI Delete Deletes a load curve Attribute assignments must be deassigned before a loadcase can be deleted At least one loadcase will always exist in the Treeview LJ Rename modifies the load curve name LI Edit changes previously entered load curve data Notes e Load curves are only applicable to nonlinear transient and Fourier analyses e When defining load curves for transient or nonlinear analyses the time in all load curves must be defined from the start of the analysis e For Fourier analysis the load must only be applied over an angular range of 0 to 360 degrees 2595 Modeller Reference Manual e If the interpolation variable doesn t
419. ndergo large incremental or total change large displacement Common term for geometrically nonlinear analysis where the stiffness of the structure is not constant but becomes a function of displacement latent heat The additional heat gain or release required to obtain a material thermal phase change Phase change modelling requires a nonlinear thermal analysis layer Certain finite elements such as shells are based on a layered formulation See also composite properties lift off A change in a support condition that allows movement away from a support in a certain direction Used where a structure rests on a foundation but there is no restraint to stop the structure from moving upwards if loading conditions dictate limit point A local maximum point on the load displacement curve See also bifurcation point line Feature defining a structural edge passing through any number of points line search A technique used to improve the convergence rate of Newton iteration by minimising potential energy See also constant load level arc length method line section See section line linear analysis An analysis where the relationship between stress and strain is a straight line linear buckling See eigenvalue buckling 446 Index link element A thermal line element similar to structural joint which transmits temperature along its length by conduction convection and or radiation load combination The result
420. ndex direction keys See arrow keys directory Part of a structure for organising your files on a disk A directory can contain files and other directories called sub directories The structure of directories and sub directories on a disk is called a directory tree discrete point and patch loads May be used to distribute a given loading pattern over a number of features Point loads apply a series of discrete point loads and patch loads apply an interpolated loading patch based on specified apex values A so known as HA HB loading General loading See also highway loads discretisation Sub division of features into finite elements disk drive A device used to read from and write to disks See also hard disk floppy disk disk usage The amount of hard disk space used during an analysis See also hard disk diskette See floppy disk displacement The amount by which a node moves during loading is known as the displacement displacement norm A LUSAS convergence parameter which expresses the limit for the sum of the squares of the iterative displacements as a percentage of the sum of the squares of the total displacements See a so residual norm work norm convergence displacement vectors Arrows drawn on the screen to represent the direction and magnitude of resultant displacements for a model See also vector plotting principal stress vectors distributed element loads Form of element load in which a load variat
421. ned to Surfaces Examples of Assigned Non Structural Mass Elements Lumped mass at a point Distributed mass along a line Distributed mass over a surface Non Structural Mass Local Axis Direction Since the mass can be used to model hydrodynamic effects it is defined in local directions In the case of a line the direction may need to be normal to the line or in the case of a surface normal to that surface When carrying out large deformation analyses these directions are continually updated as the solution progresses The element axis direction can be defined when the mesh is assigned Three axis orientation options are available LI Follow point axes Default selection Adopt the axes assigned from the Local Coordinate if any assigned to the point Any Local Coordinate that has been assigned to a feature can additionally be chosen to be ignored as a separate option LI By point in selection memory A Point previously added to selection memory is used to define the xy plane LI By specified local coordinates The element axes are defined using a previously defined Local Coordinate Delamination Interface Elements Interface elements may be used at planes of potential delamination to model inter laminar failure and crack initiation and propagation If the strength exceeds the strength threshold value in the opening or shearing directions the material properties of the interface element are reduced linearly as defined by the materia
422. new selection is picked on the Contours property dialog accessed via the Layers LK Treeview e A black dot next to a group symbol denotes the current group into which all new geometry will be added when created and hence has no relevance when viewing results Plotting Results for Assigned Attributes By default results are computed and displayed on the visible model With appropriate layers present in Layers Er Treeview results can be selectively plotted for attributes held in the Attributes db Treeview by right clicking on the attribute name and then choosing Results Plots The following context menu commands are available for Results Plots LJ Show Results LJ Do Not Show Results LI Show Results Only On This Attribute When combined with visibility options that can also be accessed via the context menu for each attribute selected features of the model can be isolated and have results plotted just for those features This provides a means of producing isolated results for particular material types geometry or element mesh types without having to define individual groups for each of these items But if required groups of features or elements may be defined and the Results Plots entry may be used to display selected results for a chosen group Notes e When choosing to show results for a material geometric property or element mesh type that does not support for example the same Contour entity as that used for the previously plotted it
423. nformation for subsequent conversion to an alternative file format using the LUSAS picture file utility program Expose LUSAS picture files are stored in readable ASCII text format The individual picture file records use the following general format code rl r2 r3 r4 il i2 13 The information is stored in packets of data as defined in the following table 54 Code Function 20 Move Draw Symbol Character Colour Clipping Rectangle Multi Line Text Parameters r1 r2 r1 r2 r1 r2 r3 r4 i1 r1 r2 r3 r4 i1 r1 r2 r3 r1 r2 r3 r4 i1 r1 r2 r1 r2 r3 r4 r1 r2 r3 r4 11 i2 Saving Picture Files Print Files Chapter 3 Description Moves to the drawing location specified by the x r1 and y r2 coordinate mm Draws a line from the current position to the drawing location specified by the x r1 and y r2 coordinate mm Plots a LUSAS built in symbol at a specified screen position 0 Square 1 Circle 2 Triangle 3 Double Triangle 4 Diamond 5 Cross 6 Boxed Cross 7 Asterisk 8 Horizontal Arrow origin at apex 9 Horizontal Arrow origin at base 10 Vertical Arrow 11 Vertical Line 12 X 13 Y 14 Z 15 Barred X Plots an ASCII character at a specified screen position with x coordinate r1 y coordinate r2 rotation angle in degrees r3 character height in mm r4 and ASCII character code i1 Percentage colour content with red
424. ng Geometry Element Orientation For feature based models the orientation of the Geometry is used to define the local axes of the elements For mesh only models the local axes of the elements will be the same initially as those defined in the data file that was used to create the model The following commands enable the local axes of Lines Surfaces and Volumes and Elements for a mesh only model to be re oriented First the feature or element to be used as a basis for the re orientation to be carried out must be selected followed by the selection of any additional features to which the re orientation of the first feature or element should apply and then a menu item based upon Geometry gt Feature gt Command Q Reverse Lines Combined Lines and Surfaces can have their direction reversed This example the effect of a Line Ta reversal The local x axes of all gt gt gt _ elements on this Line will be reversed L1 111 Modeller Reference Manual In the Surface example the local x axis remains along the first Line in es 2 the Surface definition but the Surface L4 normal is reversed Elements meshed on this Surface will be inverted L1 Q Axes to Surface Volumes may have their local z direction set from a selected Surface Volume axes are defined by the direction of the axes on the first Surface in their definition This command reorders the Surfaces defining the Volume such that the first
425. ng data using the Advanced button on the File gt Save As menu item This data will be regenerated when the model is reloaded Analysis Data Files In order to perform an analysis the model must be tabulated into a LUSAS Solver data file The Solver data file has a dat extension Writing the LUSAS data file is controlled using the File gt LUSAS Datafile menu item This produces a data file in readable ASCII text format If necessary the file may be 50 Chapter 3 modified with a standard text editor The format of the analysis data file is described fully in the Solver Reference Manual The File gt LUSAS Datafile menu item allows the following options to be set in order to control the analysis process from within LUSAS Modeller Process This controls the parts of the model for which data is tabulated LJ All items default L Visible Items Solve Now If this is set LUSAS Solver will run immediately after the data file is tabulated default If this is not set a data file is tabulated but not solved When the Solve now option is set the Options button is enabled This displays a dialog which allows the following parameters to be set UO Wait for solution If set Modeller cannot be used while the solution is progressing default LI Load results If set Modeller automatically loads the results file over the model file when the solution has successfully completed default Q Load output file If set Modeller
426. ning three loadcases are considered using the permanent factor With the number of loadcases to consider set to four only the four most positive resultants will be combined for the Max combination and the four most negative resultants will be combined for the Min combination However by setting the variable loadcases only positive results will be considered for the Max combination and negative results for the Min combination Smart combination Max will assemble results from the loadcases using just the permanent factors given for negative load effects and using permanent variable factors for number of positive load effects specified by the number of Variable loadcases to consider the remaining positive load effects will only use the permanent factor The number of load effects summed is restricted to the number of loadcases specified and the other loads are also the discarded The loadcases used are the most adverse for example the most positive for max combination and all other load effects assembled are discarded Also with the variable loadcases set to one the max combination will include only positive load effects all negative load effects are discarded 395 Modeller Reference Manual Loadcase Nodal result Temperature 5 Wind Settlement Live load 1 Live load 2 Live load 3 Live load 4 5 10 15 10 Permanent factor 0 7 0 7 0 7 0 7 0 7 0 7 0 7 Variable factor 0 8
427. nnnnsennnnnnnnnnoonnnensnnnnnnnnnnnnennneesnnnnnnnn 313 RunNINO aMANAIVSIS eanas aaae a e ae a a a S a a Ee E 314 P sStANaAIySIS CHECKS zirzia E a a oR 314 Chapter 8 Viewing the RESUItS ccccceceeeeesseseeeeeeeeeeeeeeeeeeeeeeeeeeeaaeeseeeeeeeeeseeseeennoneneeeeness 317 Miodu OM oes ate eet eg ores cas A vace eat ties c nace daevena aseatvedeulestargecgunts ese 317 Results PROCESSING cusina aai aeaa E aene ET ariaa aa 317 PRESUINS NCS oaio era AEE a Ta e aN e EaR AER 319 Modeller Reference Manual Results Transformation x s ies ee es he ees ee ee 322 Combinations and Envelopes sccceeeeeeeeeeeeseeeneeeneeeeeeeeeeeeeeesseeeeeaeeneeeeaeeeeeeesssenennons 324 Wood Armer Reinforcement vseen a oaea caveat cteccasvenvewarcevescedvens 330 Fatg e Calculat ONS ocase eea Ae Ar Ee ae AES 331 Fourier FROSUING scire ea eeo ieoa E aa E aeea aeei 333 Design Factors aaaea eea Saa ie a a a a E a Eaa Ea e a a AAEE 333 Composite Layers scili caisasicnndshacien tapas sbi ven inaa vba da gaan e aa ea N R ne 334 Composite Failure Criteria cccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeeeeseeeeeeeeeeeeeeeeeeees 334 Interactive Modal DYMAIMICS ics isiccccsescicace inae aa A AEE EA I EE 335 User Defined Res lts xc acsccs cc icve card ccaceesreccetandsteaues vetvicarietdeuasvecuenendevecseacedvetasdeudcuaddedueneriete 342 VisualiSing The Results reiii inaran aaa aai aa aaa aaa aaan aaa Nan Caa aa 343 Deformed Mesh PI
428. no results are written to the LUSAS output file Results can however be written to the output file for all elements and nodes or for those in the current Selection or the Selection Memory The following options allow the results written to the output file to be specified Q Element results such as stress and strain as controlled by the LUSAS Solver options set from the File gt Model Properties menu item can be written to the output file at Node and or Gauss points and also written to a history file if required LI Node displacements and reactions can be written to the output file and a history file can also be written if required LI Generate plot file If selected configures the LUSAS Solver data file to create a plot file mys default L Generate restart file If selected configures the LUSAS Solver data file to create a restart file rst Solver Output Files When an analysis is performed by LUSAS Solver it creates a text output file which has an echo of the input data details of all errors diagnostics and warnings and tabulated results Solver Results Files When an analysis is performed by LUSAS Solver it will create a LUSAS results file The LUSAS results file or plot file as it is sometimes referred to has a mys extension For transient and nonlinear analyses the frequency that LUSAS Solver writes results to the results file is specified when defining the analysis control If this is not specified results are saved in the re
429. nonlinear thermal problem Notes e If heat transfer coefficients vary on a specified face the values will be interpolated using the shape functions to the Gauss points e Ifa non zero radiation heat transfer coefficient is specified the problem is nonlinear and Nonlinear Control must be used e Load curves can be used to maintain or increment the environmental temperature as a nonlinear analysis progresses e Automatic load incrementation within the Nonlinear Control can be used to increment ENVT loading Internal Heat User Allows user defined input of internal heat generation for an element for use with user written software programs Values can be entered in multi column format Positive loading values indicate heat generation and negative values indicate heat loss Concrete Heat of Hydration Concrete heat of hydration is defined as a part of the material model to be used See Isotropic Orthotropic Material 218 Chapter 6 Case Study Temperature Dependent Loading Temperature dependent environmental loading can be useful to model experimentally determined correlation for convective coefficients For example if the convective coefficient may be given by C deltat to the power one third where C is a constant deltat is the temperature difference between the surface and the environment To specify this loading in LUSAS you would define the convective coefficient at as many reference points as are required to give a good piece
430. nsformed Load In this example loads are projected onto a eats model normal to the patch definition The projection vector is denoted by a double headed arrow on a visualised patch The direction of the load applied to the model is defined using the untransformed load direction This example shows a typical 3D patch load where the patch is defined in space and projected onto the mode 0 Patch load divisions specifies the numbers of Discrete Extrapolated Load TAT A Patch Concentrated Extrapolation divisions in the local x and y directions of the Loads Nodal Loads 4 Path patch being assigned The divisions are used to split the applied patch into individual component loads before they are in turn used to calculate equivalent nodal loads on the model By default the patch load division are based upon the values set in the Patch divisions object which is created when a discrete loading is added to the Attributes Treeview Again by default 10 patch load divisions are used in the local x direction and the aspect ratio of the patch is used to calculate the divisions in the y direction When creating a patch ideally at least one division should be used per element division The more individual loads a patch is split into the more accurate the solution obtained Patch load divisions can also be explicity defiend on the main patch loading dialog as a number in x and a number in y In this case if X 0 and Y 10 is entered the number in the x
431. nt A spectral response analysis is available using the IMD loadcase Starting Procedure Before specifying the spectral response data the eigenvalues and eigenvectors of the system are computed using an eigenvalue extraction analysis note that the computed eigenvectors must have been normalised to the global mass Spectral Response Data Input The spectral curve spectral curve type and percentage damping are specified in the spectral curve which is part of the IMD loadcase definition The spectral curve may be defined as LL Frequency or period vs displacement Q Frequency or period vs velocity LI Frequency or period vs acceleration 299 Modeller Reference Manual To compute the participation factors it is necessary to specify the direction of excitation The excitation may be specified simultaneously in three directions The factor specified in each direction is used to scale the spectrum intensity in that direction For each mode the spectral displacement is determined from the frequency and this is multiplied by the participation factor and the excitation vector to determine the response Damping may be specified for each mode of the structure or at known frequencies of vibration If damping is only specified for the first Eigen mode this value is applied to all modes When the percentage damping specified on the spectral curve differs from that specified in the viscous damping a correction is made to the spectral displacement
432. ntation are available Q Uniform Incrementation By default uniform incrementation will be applied That is for each increment the current load factor will be multiplied by the specified load components to generate the applied load Q Variable Incrementation Alternatively variable incrementation may be requested In this case the current load factor will be automatically varied according to the iterative performance of the solution The variation is a function of the required number of iterations and a specified desired iterative performance Thus where the number of iterations taken is less than the desired value the incremented load factor will subsequently be increased and conversely if the number of iterations is greater than the desired value it will be decreased Variable incrementation may be used in conjunction with either constant load level or arc length solution methods and is an effective way of automatically adapting the performance of the solution procedure to the degree of nonlinearity encountered The overall effect is therefore to increase and decrease the numerical effort in the areas of most and least nonlinearity respectively Mixing Manual And Automatic Incrementation If required manual and automatic incrementation procedures may be mixed freely When mixing manual and automatic incrementation the following rules apply e Loadcases may be respecified as often as required e Ifthe automatic procedure is specified it wil
433. nts Deselects the features that have the selected attribute assignment Q Visualise Assignments Switches on and off the visualisation of features that have the selected attribute assignment in the chosen style Q Update from library Updates any attribute data held in the model for the selected attribute if a section library item or material has been updated since first used Q Assign Assigns the selected attribute to the selected features The attribute will only be assigned to features for which the assignment would be valid Some attributes require further information in order to be assigned and in these cases a dialog is displayed For attributes that can only be assigned once to a feature assigning another attribute will overwrite any previous assignment of that attribute type LI Deassign Deassigns the selected attribute Choose From All or From Selection LI Set Default Automatically assigns the selected attribute to all new features as they are created Visualising Attribute Assignments Attribute assignments can be visualised using Attributes layer The Attributes layer is a window layer in the Treeview that is normally added during the initial start up of Modeller The Attributes layer properties define the styles by which assigned attributes are visualised The attributes layer properties may be edited directly by double clicking the layer name in the fail Treeview Attributes can also be visualised individually by selecting an
434. nual The error message includes the node and variable number that may be affected by the poor conditioning these variables should be investigated in the model Typical mistakes can include e Omission of a support condition in one or more of the rigid body directions for the structure e Insufficient additional restraint when connecting a beam element to a continuum element In this case a rigid body torsional spin about the axis of the beam may occur e Six degrees of freedom have been specified for a thick shell element but the drilling rotation has not been correspondingly restrained e Insufficiently large slideline interface stiffness coefficients allowing the two bodies to pass through each other as rigid bodies The load increment may also be too large e Incorrect nonlinear material parameters such as a zero yield stress e Joint elements may require investigation as the stiffnesses operate in local directions and can be easily defined incorrectly as a result the joint stiffnesses will not be providing support in the required directions e There may be totally or partially unconnected elements within the structure as a result of incomplete merging or equivalencing of the model Other Warnings Other warnings that may be found in the LUSAS output file include LI Aspect ratios warnings See the appendix on element restrictions in the Element Reference Manual for more information LI Excessive curvature for beams warnin
435. nual wdi file A windows definition language file used by LUSAS GRAPHICS to define the main menu bar and associated pull down menus wildcard A character that represents one or more other characters For example exe represents all files that end with the exe extension window A component screen area within the LUSAS GRAPHICS work area For example graphics window text window Wood Armer Method of calculating the moments of resistance required in reinforcement that are placed in any two directions of a linear solution word The set of bits comprising the largest unit that the computer can handle in a single operation work norm A LUSAS convergence parameter which expresses the limit for the work done by residual forces based on iterative displacements as a percentage of the work done by the loads in the first iteration of a nonlinear problem See also convergence displacement norm residual norm write protect An action that can be taken with a diskette to prevent data being written to it There is a switch in the corner of the diskette which when moved into the open position write protects the diskette XMS memory Extended memory that can be accessed by using the eXtended Memory Specification from Lotus Intel Microsoft and AST LUSAS applications work with an extended memory manager which makes sure that only one application is using a portion of memory at any one time yield criterion The condition used to establish whe
436. nular materials such as rock and soils The model incorporates isotropic hardening and dilatancy Q Drucker Prager Model 64 Represents ductile behaviour of materials which exhibit volumetric plastic strain for example granular materials such as concrete rock and soils Incorporates isotropic hardening LI Concrete Model 94 A two and three dimensional concrete material model that accounts for non linear behaviour in both tension and compression It is able to model both cracking and crushing behaviour LI Stress Resultant Model 29 May be used for certain beams and shells The model is formulated directly with the beam or shell stress resultants plus geometric properties therefore it is computationally cheaper Plastic Material Models Orthotropic LL Stress Potential Hill and Hoffman models These models are available from the Attributes gt Material gt Orthotropic menu item by choosing the Plastic check box on the material attribute dialog 165 Modeller Reference Manual The stress potential model defines nonlinear material properties applicable to a general multi axial stress state requiring the specification of yield stresses in each direction of the stress space Incorporates hardening yield stress and Heat fraction Hoffman is a pressure dependent material model allowing for different properties in tension and compression The linear rigidity model is used to define the in plane and bending rigidities from prior explici
437. nvalues extracted and will be in the following format 298 Chapter 7 MODE EIGENVALUE LOAD FACTOR ERROR NORM 1 33 0456 33 0456 0 190087E 10 2 64 3432 64 3432 0 179595E 07 3 130 903 130 903 0 202128E 11 The buckling load for a mode is obtained by multiplying the actual magnitude of the applied loading by the load factor 33 0456 in the case of the 1st mode Absolute displacement output is not available from any eigenvalue analysis It is available however in a normalised state For buckling analyses the eigenvectors mode shapes are normalised to unity where the maximum translational degree of freedom is set to one mass normalisation is not applicable to buckling analyses The mode shapes are therefore accurate representations of the buckling deformation but do not quantitatively define the displacements of the structure at the buckling load Reactions stresses and strains represent the distribution at the buckling load again their magnitude is not quantitative Spectral Response Analysis To study the effects of ground motion excitation on structures it is necessary to input the intensity of the motion One practical measure can be obtained from a knowledge of the response spectra Spectral response analysis seeks to determine the response of a structure subjected to a specified support excitation using modal superposition This can be achieved without recourse to direct integration of the model over the complete duration of an eve
438. o aid visualisation at the connections When processing results the deformed cross section shape may also be visualised by selecting the Deform option on the geometric properties dialog Visualisation of Attributes Without Fleshing Visualisation of Attributes With Fleshing Notes e Geometric properties can be varied along a line using a tapered section definition or by using the multiple varying section facility e Geometric properties can be varied over a surface by using a variation See Variations for more details e Geometric attributes are not required for plane strain axisymmetric solid or 3D solid elements e The geometric attributes are specified in a generic form for all elements and only the properties required for the intended element need be specified For example eccentricity is reported as a error if assigned to semi loof shell elements which do not use it in their formulation e For more details on the properties required for a specific elements refer to the Element Reference Manual Section Library The section library is available from the Attributes gt Geometric gt Section Library menu item Standard section libraries are currently available for the following LJ Australia steel sections L Canada steel sections 152 Chapter 6 0 China steel sections LI EU steel sections LI KS steel sections Korean Rail Sections LI UK steel sections LI US steel sections In addition user created section prope
439. oading can be defined either by directly specifying a constant body force load or by defining its existence as a property of a structural loadcase Global Distributed Load CL Defines concentrated force or moment loads in global or transformed nodal axis directions Concentrated force loads are applied to all nodes underlying the feature onto which the load attribute is assigned Nodal freedoms can be transformed using local coordinate sets The following sub types are supported LI Total applies nodal load values calculated according to contributions from surrounding elements and to element nodal weighting values e g loads are weighted with ratios 1 4 1 at nodes along the edge of a quadratic shell in such a way as to make the shell strain equally Q Line per unit length applies nodal loads using the specified values per unit length loads Must be assigned to Lines Q Surface per unit area applies nodal loads using the specified values per unit area loads Must be assigned to Surfaces Face Load FLD Defines face traction values and normal P Structural Face Load loading applied in local element face Z 1 0 directions Face loads are applied to the a edges of plane elements or the faces of solid elements This type of loading is applicable Eisiieni to 2D and 3D continuum elements and Axes certain shell membrane and thermal elements In the example shown a local y direction o p ve ete y Axes structural face load is as
440. oads that extend beyond a search can be included or excluded using LI Options for loads outside search area Loads that fall outside the search area can be moved into the search area or be excluded entirely using a variety of options See Processing Loads Outside Search Area General loadcase information that can be entered includes Q Loadcase specifies in which loadcase the loading is to be applied Loadcases can themselves be manipulated See Loadcase Management for more details LI Load factor specifies a factor by which the loading is multiplied before the equivalent nodal loads are calculated Editing of Discrete Loading Data Editing of pre defined discrete loading data such as that used for supplied vehicle loads allows users to view both the original vehicle definition input data as well as the actual loading applied the vehicle load converted into a discrete load format for any and all vehicles within LUSAS Editing of user defined discrete loading data only permits viewing and editing of the discrete loading data So for the case of creating a vehicle load from a pre defined vehicle the resulting attribute in the Attributes Treeview has context menu entries named Edit Definition and Edit Attribute These menus can be seen by right clicking on the attribute e Selecting the Edit Definition menu entry or double clicking the attribute displays the original definition dialog with all the original input data intact The
441. ocations along the beam by linearly interpolating the cross sectional area A and Moment of Inertia I values of the sections defined at each beam end This method has generally known limitations for particular section types Note that when modelling varying cross sections with constant section beam elements care should be taken to ensure that sufficient elements have been assigned Greater than 8 elements should be used for small variations in cross section along the length of the geometry to which the section has been assigned and considerably more elements should be used for larger variations Attribute name The full name of the geometric line attribute added to the b Treeview will include the Attribute name followed by an automatically created name based upon the number of section library items used If section properties of this geometric line are manually edited the automatically added part of the attribute name in the ob Treeview is removed The automatically created part of the name is uneditable if a rename is carried out Once defined the geometric section properties are added to the ob Treeview using the OK or Apply button The section is then available for assigning to the appropriate lines on the model Assigned beam section properties may be fleshed using the fleshing button Ei or from the db Attributes Treeview 156 Chapter 6 Section visualisation As the multiple varying section is built up in the table a visualisa
442. ode used by most computers for interfacing aspect ratio The ratio of longest side to shortest side of a finite element It is important to take the aspect ratio into account as the quality of results is affected when it becomes too large 422 Index assign To match up a feature with a previously defined attribute you assign the attribute to the feature association See associativity associative plasticity Plasticity formulation where the direction of plastic straining is normal to the yield surface This is a common finite element implementation for non granular materials associativity All features in LUSAS are defined in terms of lower order features that is they are associative When a point is moved all lines surfaces and volumes are updated to reflect the new position assumed strain A strain field used in the formulation of the general shell element to avoid shear locking when it is used as a thin shell attribute See attribute dataset attribute dataset Describes the properties of features to which it is assigned for example materials mesh loading etc automatic incrementation Analysis scheme where successive levels of applied load are applied by specifying multiplying factors for a given load case Successive load levels can be altered based on the previous convergence history automatic masters A facility within a LUSAS Guyan reduction in which LUSAS automatically selects the master freedoms
443. odeller Reference Manual steady state response The response of a system when all of the transient components have become insignificant See also transient response steepest descent method Implicit plasticity algorithm by which inadmissible elastic trial stresses are returned to the yield surface step by step dynamics See direct integration dynamic analysis stiffness matrix The matrix containing terms that relate the displacement of a structure to the applied forces See also b matrix d matrix strain energy The work done by an external force in displacing a structure is stored as strain energy It may be released on unloading for elastic analyses or cause permanent deformation in elastic plastic analyses strain hardening The ability of a material to continue to accept stress following NL yielding usually at a reduced rate strain softening Post yielding or cracking behaviour whereby continued loading results in a release of accumulated stress and a negative stress strain slope It is often called tension stiffening with reference to the biaxial concrete model stress recovery The process of calculating the stress results from the deformed shape and stiffness matrix stress vectors See principal stress vectors stress resultant Generally useful in civil design and defined as stress per unit length or width Conversion to a stress is achieved by dividing by the thickness string A character based variable
444. oenseesooees 140 Delamination Interface Elements rasmida adaa aada eiae aaa aaa aiT 141 Element SCIECTION carii E 144 Point Element Selecti istiora anaa a aa a eaaa eaaa aaar 144 Line Element SelecHo Micaria inerant eU ienie anaiakin 145 Surface Element Selection nnnnunnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn eae aa ee 146 Volume Element Selection n nnnnnunnnnnunnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nn a nenna 146 Geometric Properties ssiri anae EAOa EARO ER NANKO KANAA 147 SOECHION LIDT ANY riria E S NE AEEA 152 Multiple Varying Sections ssssssnnsnnnuunnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nnmnnn nnmnnn nnmnnn nennen 153 Material Properties iseia rana iaaea a a aaa ae aaa aeai eaaa aiaa et aaar aaa aaant 162 Material Library icici ciceecscouctecansawechtanvscedassucetiscouseecensaveehcanuseec en aeaaee aea aeaaaee Eana 164 Composte LIDAR caan E sna racceuevnnccececumereaneatectceeenerens 164 ISotropic Orthotropic Material iessen eienn aea a EE ER 164 aielo lin AAEE e PE E E E T E E E T E E E 166 Thermal Material rsisi an aaa a aa AeA aaa ao aa AR Ea 166 Stress Potential von Mises Hill Hoffman cccsscceeesseeseeeecenseeeseenseeeseenseeeseenseeeees 167 Optimised von Mises Model 75 sccceeceeceesseseeeeeeceeenseeeeeeeeeeesseeeeeseoeenseeeeseeeoensnenees 168 Tresca Model ON eee a are Oa ND Na ee ac 169 Non Associated Mohr Coulomb Model 65
445. of a position in a structure where the applied moment has exceeded the plastic moment capacity resulting in a loss of rotational stiffness or hinge plasticity A nonlinear material description associated with yielding of material e g metals plastics soils 454 Index plot See contour plot plot file The binary results file written by the LUSAS solver which is used to pass results information to the post processor plot scale The ratio of screen coordinates to model coordinates is known as the plot scale point Defines the coordinates of the vertices of the structure point load See discrete point and patch loads poisson s ratio A material property value indicating the amount of a longitudinal strain that is translated into a contraction due to lateral strain in a Hookean material polar decomposition Method of decomposing a deformation gradient into a stretch and rotation tensor See also deformation gradient polar second moment of area For a plane area in the XY plane the polar second moment of area is defined as the integral of X squared plus Y squared over the area of the section The polar second moment of area thus equates to the second moment of area about the x axis plus the second moment of area about the y axis For circular sections the second polar moment of area is equal to twice the second moment of area about the x or y axis Also known as torsional moment of inertia post processing Th
446. of iterations an upper limit on the number of conjugate gradient iterations to be processed the default value is 5000 If the convergence criterion has not been satisfied when the iteration limit is reached LUSAS Solver will issue a warning and then continue the analysis For the iterative solver the following points need to be taken into account Conjugate gradient methods can only be used for problems having symmetric positive definite matrices By definition standard linear static analyses yield positive definite matrices in general but mixed formulation problems such as pore pressure models do not Problems involving constraint equations cannot currently be solved with the iterative solver since the resulting stiffness matrix is non positive definite For problems with multiple loadcases iterative solvers are less efficient since a separate iterative process is required for each loadcase and the total time taken will increase in proportion to the number of load cases By contrast direct solvers incur very little extra cost when solving for multiple loadcases Guyan reduction and superelement analyses cannot be solved iteratively since matrix reduction does not take place When using hierarchical basis preconditioning if any midside degrees of freedom are supported or prescribed their corresponding vertex neighbours must also be supported or prescribed For example if a midside node is fixed in the x direction all nodes on
447. olution technique for solving static linear analyses The global stiffness matrix and load vector s are assembled and is designed to run entirely in memory Three preconditioning techniques are available to assist the convergence rate of the conjugate gradient method Standard The incomplete Cholesky preconditioning technique is the most robust provided an appropriate drop tolerance is chosen and is applicable to all analyses for which the conjugate gradient solver may be used Decoupled The decoupled incomplete Cholesky preconditioning technique may be used for all analyses except those involving tied slidelines thermal surfaces and Fourier elements It generally leads to faster overall solution times than Incomplete Cholesky preconditioning although more iterations are required for convergence For less well conditioned problems the conjugate gradient algorithm may not converge using this technique so care should be taken Hierarchical The hierarchical decoupled incomplete Cholesky preconditioning technique is only available for models consisting entirely of two and three dimensional solid continuum quadratic elements and offers excellent convergence properties It is by far the most effective technique for models of this type and when used in conjunction with fine integration allows solutions to be obtained for relatively ill conditioned problems For very ill conditioned problems of this type e g where the average element
448. olve the stiffness matrix Often occurs due to insufficient specification of boundary conditions slave freedom Freedoms in a model where the mass contribution of the inertia effect can be considered to be relatively insignificant See also master freedom Guyan reduction retained freedom slide surface A 3D contact surface made up of surface boundaries See also slideline slideline A 2D contact surface made up of line boundaries See also slide surface slides Contact and impact problems may be analysed with the use of slide lines or slide surfaces on the contacting features The LUSAS contact facility uses the penalty function approach See also slideline slide surface penalty function smoothing The process of creating a smoother transition between stresses in adjacent elements by using a calculated nodal average value at common nodes See a so averaged nodal results unaveraged nodal results small pivot Indicates a poorly conditioned stiffness matrix See also diagonal decay negative pivot snap through Large deflection nonlinear effect whereby a structure converts membrane to bending energy and adopts a stable but usually inverted configuration solidification See phase change 462 Index spawn The action of creating a sub process to carry out a specified task LUSAS Graphics can spawn a process to run LUSAS Solver on UNIX machines spacing ratios Used by line mesh datasets to express the variation
449. om CAD systems when such merging may be difficult or impossible Once defined hollow volumes behave in almost exactly the same way as normal solid volumes For example they may be meshed and have attributes assigned and deassigned in the usual way The main difference is that in a geometric Boolean operation a hollow volume will behave like a set of surfaces hence the name Hollow volumes may be open or closed To understand the difference consider just one defining edge of the volume get Pe between two defining surfaces If that edge consists of a exactly one line or exactly two lines of very similar length m e d and shape then those lines can be considered a matching pair If all the defining edges of the volume can be matched in this way the volume is said to be closed However if one or more edges of the volume cannot be matched in this way then the volume is said to be open ae For the example shown most of the lines form matching pairs However one of the defining surfaces has an edge that is defined by two lines with a point in the middle This pair of lines cannot be matched to the corresponding single line on the adjacent surface and so this volume is open The distinction between open and closed hollow volumes is only important when it comes to meshing A closed hollow volume can be meshed in exactly the same way as a normal solid volume However a regular mesh cannot be assigned to an open hollow volume and so these mu
450. om the View menu Q Working Mode is useful for model generation In working mode annotation is scaled and moved so it is always visible 39 Modeller Reference Manual LL Page Layout Mode enables the model to be viewed as it would appear on a printed page This makes annotation easier to position and allows pictures to be created to a specified scale Scaling In Page Layout Mode the model is scaled and positioned within the margins defined using Page Setup gt File menu item This behaviour may be modified by toggling the scale to fit window 2 button If a picture is to be created to a specified scale the page size should first be set using the File gt Print Setup menu item The desired scale and position should then be set on the View tab of the Window Properties accessed from the context menu In this dialog the scale to fit window option should be switched off and the scale and origin position defined Annotating the Model The view window may be annotated using the Utilities gt Annotation menu item Annotation can be placed by either cursor positioning or by specifying a coordinate location in Frame or Model coordinates Annotation added to the model is displayed in the Annotation layer in the Treeview Cursor positioned annotation Q Line Single lines may be added in a selection of colours and line styles Q Polygon Filled or unfilled polygons may be annotated on the screen in a selection of colours Left click to in
451. ometry and line segment information from a spreadsheet e By defining a path from lines arcs and splines in LUSAS Modeller The way that two adjacent and intersecting reference path lines will be shaped can be controlled by smoothing which involves adding a radius transition between two lines inside of their defined intersection point or adding a radius transition between two lines through their defined intersection point Transverse direction settings control how line attributes containing multiple varying sections are assigned to more than one set of lines when using the same common reference path One example of use is for straight or skewed grid or grillage line beam models For this type of modelling a single reference path can be used in conjunction with a transition setting to offset multiple tapering section line attributes appropriately for each longitudinal beam member Value of distance at start of path can be used specify the local x value at which the path should begin For bridge engineering this equates to specifying a chainage value for a known setting out point This value is added to the distance value that can be displayed for each of the points defining the path Reference paths for 3D line beam models For 3D line beam models consisting of multiple longitudinal lines a reference path can be used This allows one multiple varying section geometric line attribute to be assigned to multiple lines The number of line beams requi
452. on support surface Four sided surface used to define the internal geometry of an irregular non planar surface supports Describe how the model is restrained at its boundaries or may be used to infer symmetry conditions on a model surface Feature defining the faces of the structure Defined as being bounded by lines See also regular surface irregular surface ruled surface system parameters The LUSAS Graphics and LUSAS Solver databases may be tuned on initialisation using system parameters in the start up file tabulation The process of creating an analysis data file from the pre processing model file 465 Modeller Reference Manual tangent stiffness The formation of the stiffness matrix at a given equilibrium position temperature gradient The variation of temperature through the thickness of an element This distribution induces bending termination Completion point of an analysis Termination is controlled using the termination line in a nonlinear or dynamic control text output window A separate window is created to display information in a text format requested by the user See also message window graphics screen thermal analysis See field analysis thermal gap A space between two bodies in a thermal analysis through which heat will flow thermo mechanical coupling See coupled analysis thick element formulation An element formulation that includes the effect of transverse shear deforma
453. on with respect to another LI Usage Selects the element type for which the varying section properties will be defined LI Specify shape interpolation Allows selection of an interpolation type If unchecked a smoothed option is used Q Distance interpretation settings specify the method of spacing the sections Section selection In the section selection table the sections that will be used to generate a varying cross section along a line or path of lines are each added to the table and an interpolation method and a distance from a starting point is specified for each User defined sections need to be saved to the local or server libraries prior to using this facility 153 Modeller Reference Manual Q Section Clicking on the launch dialog button I in this cell allows a pre defined section to be chosen from the section library LI Shape Interpolation Clicking on the drop list button in this cell permits the definition of a smoothed linear quadratic or a function based interpolation setting The shape interpolation setting defines the shape between adjacent pairs of defined sections This is only available for second and subsequent entries in the table Q Distance specifies a value for a chosen distance type Distance type LI Scaled to fit each line individually Values must be entered in the Distance cells of the table to represent the locations along a line that the sections will apply Values are entered either as proportional
454. on analysis is carried out automatically prior to the subspace iteration algorithm which uses the approximate eigensolution from the Guyan reduction as the first estimate of the exact solution By making the correct assumptions and approximations it can be shown that a Guyan reduction analysis produces the same results as the first iteration of the subspace method with the starting iteration vectors as constructed by the first method details of this can be found in the Theory Manual Using Eigenvalue Shifts An important procedure that may be used in eigenvalue extraction is shifting If rigid body modes are present in the system the stiffness matrix will be singular hence causing numerical problems in the subspace iteration and the Guyan reduction algorithms To overcome this a shift may be applied to form a modified stiffness matrix of which the associated eigenvalues will all be positive To obtain the actual eigenvalues the shift is automatically subtracted from the calculated eigenvalues The eigenvectors for both systems are the same The frequency shift enables the eigenvalues of unrestrained structures to be computed by removing the zero diagonal terms from the stiffness matrix The convergence rate of the iterative eigenvalue solution procedure will increase with a smaller shift provided the shift is large enough to avoid numerical problems Guyan Reduced Eigenvalue Extraction Good finite element approximations to low frequency natu
455. on and the calculation of particular effects The Direction definition dialog is accessed from the Utilities gt Direction Definition menu item The options are 2 3 Modeller Reference Manual Vertical Q Global axis This determines the direction that gravity loading will be applied if added using the Bridge gt or Civil gt Gravity menu item It also defines the initial vertical axis and orientation of element types and library items as displayed on the Geometric Line dialog prior to them being added to a model It also defines the model orientation viewed when using the isometric dimetric and trimetric views Note that setting the vertical axis on the Direction definition dialog will supercede any vertical axis setting defined on the Vertical Axis dialog Longitudinal Q Global axis For the majority of models this will simply be the global X axis However LUSAS allows generic input of any direction which may even be a complex path through or along a structure such as that defined by a set of lines forming a continuous path Local axis Use a local coordinate set to define the direction An example of use is for aligning influence attributes along a singly curved bridge deck Follow line path If a path of lines is to be used selecting the lines to be used prior to selecting Utilities gt Direction definition will cause the correct line path definition to be automatically inserted into the line path field An example of use is for
456. on can be specified and by default it is assumed 242 Chapter 6 that all plies are of the same thickness but this can be modified It is not necessary to select a draping surface or to define a start point when using this option Notes e The coordinates of the ply data in the FiberSIM or Simulayt file must coincide with the coordinates of the drape surface e Any XML file should only contain lay up data relating to a single drape surface For example if a non composite core is sandwiched between two composite skins then at least two XML files will be required The volumes defining each skin must be selected in turn and the appropriate XML file assigned to it e A draping grid can be extended by one grid row to ensure the edges of the component are fully enclosed See Extending the draping grid Draping in General Composite attributes may be orientated on a solid or shell model by specifying a start point and a local coordinate defining the drape direction of each lamina Draping assumes the thickness remains constant and hence the volume fraction the amount of fabric to resin in a lamina is adjusted when the fabric is distorted After assignment of a composite attribute that contains draping data to a model the skew angle and fibre volume fraction may be contoured and the fibre orientations may be visualised Notes e The native draping functionality in LUSAS is controlled by Draping options accessed via the File gt Mod
457. on definition object containing information relating to setting the vertical longitudinal and transverse axes for a model is added to the Influence entry in the Attributes db Treeview once the first influence attribute has been defined mw peal ae H TE AEN f f 2 1 Modeller Reference Manual Defining Influence Attributes Influence attributes are defined from the Attributes gt Influence menu item The influence type may be a Shear force a Reaction a Moment or a Displacement A shear or moment influence type is mesh dependent For each influence type the influence direction and displacement directions need to be specified The influence direction defines the axis to be used Once created an influence attribute is held in the Attributes ob Treeview for assignment to mesh nodes or Points on a model using the standard select then drag and drop method Assigning Influence Attributes One or more nodes or Points on the model may be selected to make an influence point assignment Assigned influences are stored in the Utilities ei Treeview When assigned to the model LUSAS automatically determines the break away elements in each case Influence type symbols may be drawn at each influence location to show the type of mesh break that is being used If a model is re meshed or has its geometry edited the influence points will remain visualised with those influence points still overlying a node or Point remaining marked with an approp
458. onditioning so make sure you have seen the section titled Diagonal decay warnings However a well conditioned stiffness matrix can produce a negative pivot if LI The system is unstable an unstable structure could be passing through a bifurcation or limit point as shown in the following diagram A Bifurcation point Zs Limit point Force Alternative equilibrium path Displacement 402 Appendix B Such a bifurcation point could permit another non physical solution path to be followed because numerically it requires less energy Every negative pivot warning occurring in the LUSAS output file represents a bifurcation point A negative CSTIF value together with a negative PIVMIN value corresponds to a limit point but a positive CSTIF and a negative PIVMIN correspond to a bifurcation point although this is only the first one located in each case since limit points are detected by a change in sign of the slope of the force displacement curve See The nonlinear logfile A negative pivots sometimes occurs during the iterative solution indicating that the load step may be too big but disappear when the solution has converged If negative pivots occur and the solution will not converge then first try reducing the load step If the solution still does not converge a limit or bifurcation point may have been encountered and the solution procedure may need to be changed Running the problem under arc length control give
459. onents are selected on the 324 Chapter 8 Combination and envelope options dialog after an analysis has been carried out an option to calculate results for the components selected is provided These results will also be cached in the Modeller results file to speed up results viewing If a model is saved these calculated results will also be saved Combinations and envelopes can consist of any other available loadcase results including other combinations and envelopes Combinations and envelopes may contain results from more than one results file if there are other results files open Two types of combinations may be defined LI Basic combinations enable a single factor to be applied to each set of results included in the combination properties LI Smart combinations enable two factors to be applied to each set of results The first factor is known as the permanent factor as it is always applied The second factor is known as the variable factor as it is only applied if the load effects are adverse A maximum smart combination Max will assemble results from the loadcases selected using just the permanent factors for negative load effects and using permanent and variable factors for positive load effects A minimum smart combination Min will assemble results from the loadcases selected using just the permanent factors for positive load effects and using permanent and variable factors for negative load effects If the Loadcases to c
460. ons These allow control of a coupled analysis Coupling type defines which analysis to run first Thermal or Structural Parallel coupling requires both analyses to run simultaneously such that the temperatures from the thermal analysis are read into the structural analysis and the displacements from the structural analysis into the thermal analysis If the temperatures are to be calculated in a thermal analysis and then transferred to a structural analysis this option is not required Initialise reference temperatures takes the first temperature distribution from the thermal analysis and uses them as the reference temperatures in the structural analysis Suppress recalculation of view factors in coupled analysis Turns on off the view factor recalculation The option should be turned on when the radiation surface geometry is unchanged by the structural analysis to suppress the re calculation of view factors LUSAS Solver option 256 Step coupling is used for coupling thermal to structural analysis such that the nonlinear increment is used to control the coupling steps Time coupling is used for coupling thermal to structural transient analysis such that the time is used to control the coupling steps First data read and first data write are the time increment to read write the first set of data Q Draping Options The draping options control the composite lamina draping process The draping process works by effectively draping a sq
461. onse Participation Factc A 6906 38 20 5391 275153 76 6668 306451 387 758 632497 32 6613 835999 145512 96840 36 2858 102043 80 448 104079 123 953 108707 186 294 120797 46 7665 Participation factor Oo o oO tH Eigenvalue Participation Factor X axis Eigenvalue Participation Factor Y axis Eigenvalue The graph window is split in to the graph area on the right and the graph data table on the left Tip Zoom in on a part of the graph by boxing with the mouse To unzoom right click on graph area to display the context menu and select unzoom Plotting Families Of Curve Data On The Same Graph If a graph already exists then further curves may be added to the first graph by choosing the Add to existing graph option of the final page of the Graph Wizard In this way families of curves may be drawn on the same graph using a different colour for each one 366 Chapter 8 Editing Graphs Once a graph has been plotted the appearance and even the data on the graph may be modified This may be done by selecting the Edit gt Graph Properties menu item from the graph context menu Editing Graph Data To change individual data points on the graph for example to add an origin to a curve make the graph data table editable by checking the Editable graph table box on the General Graph Properties page of the Graph Properties dialog The following facilities are then available
462. onse of the structure The following numerical integration schemes are available Q Central Difference Q Hilber Hughes Taylor Implicit and Explicit Dynamics Dynamic analysis may be performed using two methods 300 Chapter 7 Q Implicit Dynamics Implicit methods require the inversion of the stiffness matrix at every time step and are therefore relatively expensive but unconditionally stable By default the Hilber Hughes Taylor is used Q Explicit Dynamics In contrast explicit methods de couple the equilibrium equations hence removing the necessity for stiffness matrix inversion Explicit methods are only stable for a range of time steps determined by the problem being analysed and the discretisation adopted Explicit methods are automatically invoked by specifying explicit dynamic elements In this instance the central difference scheme is mandatory and chosen by default For explicit analysis lumped masses must be used Starting procedure To start a dynamic analysis a knowledge of the initial conditions is required The initial conditions for the Hilber Hughes Taylor integration scheme are Vi Vo 1 y Ao yA At where O 1 are the velocities at time steps 0 1 0 1 are the accelerations at time steps 0 1 Cis the time step y is the Hilber Hughes Taylor integration constant gamma 7 The initial velocity O and initial acceleration Ao can be defined in an implicit dynamics analysis The starting condit
463. onsider option is chosen and an appropriate number entered the smart combinations will be assembled in the manner described above but the number of loadcases considered will be restricted to the number of loadcases specified The loadcases used will be the most adverse for each combination 1 e the most positive for maximum combinations and the most negative for minimum combinations All other load effects will be discarded If the Variable loadcases option is chosen and an appropriate number entered the smart combinations will be assembled in the manner described above but two further criteria will be invoked Firstly the maximum combination will include only positive load effects all negative load effects will be discarded Likewise for the minimum combination which will include only negative load effects Secondly the number of variable load factors used will be restricted to the number specified The most adverse variable factors will be used in each combination and the remaining loadcases which produce load effects of the correct sign will be included with their permanent factors only Different factors for permanent and variable effects may be specified for each combined results loadcase The Permanent load factor is always applied while the Variable load factor is only applied if the effect is adverse These options may be optionally displayed as Beneficial load factor and Adverse load factor respectively if the appropriate check box ha
464. option To identify critical vehicle loading patterns on bridges vehicle load optimisation is available for Bridge and Civil amp Structural software products only See Application Manual Bridge Civil amp Structural for details Discrete loads are useful for applying a load that does not correspond to the features Zt underlying the mesh A patch may be spread AAA i or skewed across several features LUSAS BREE automatically calculates the nodal LEELA LLY distribution of forces that is equivalent to the LLL total patch load This example shows a LAE typical set of point loads assigned to a grillage model A single point a groupof6 x and a group of 16 point loads are shown The coordinates of the vertices defining the patch are relative to the Point to which the patch load is assigned 1 e a load definition is defined in a local coordinate system the origin of which is given by the coordinates of the Point to which the load is assigned The Point does 201 Modeller Reference Manual not have to lie on the Surface to which the load will be applied as the patch load is projected in a specified direction Using Search Areas with Discrete Loads A discrete load is distributed onto the elements over which the load lies A Search Area is a way of controlling the load distribution onto these elements If no search area is specified when assigning the load then all of the underlying elements will be eligible for
465. or multiple eigen modes and at a single node or over the whole structure LI Response at a node Use the Graph Wizard to produce a graph of a specified results type against sample frequency range or time steps LI Response for all nodes Use an IMD loadcase to calculate the modal response of the whole structure to a specific frequency or at a particular response time The results from the IMD calculation are then viewed using any of the standard plotting techniques such as contouring Assumptions The working assumptions for the modal dynamics facility are as follows Q Linear The system is linear in terms of geometry material properties and boundary conditions Q No Cross Coupling There is no cross coupling of modes caused by damping This is reasonable as long as the damping of the structure does not exceed 10 of critical damping Q Low Modes Dominant The response is dominated by the lowest few modes 335 Modeller Reference Manual Performing Modal Response Calculations Both the Graph Wizard and IMD Loadcase commands are initiated from the Utilities menu The basic steps for both methods are as follows 1 Decide whether to perform a response analysis on a single node Graph Wizard or the whole structure IMD loadcase Select Eigen Modes Specify which modes to include in the analysis Damping Specify the amount of modal damping Excitation Apply a form of dynamic excitation to a specific node or at the supports a E
466. or defining Volumes directly LI By using the Shape Wizard to create regular volumes Q By selecting Surfaces to define a Volume from four or more selected connected Surfaces The Surfaces may be entered in any order When defining Volumes in this way any number of Surfaces may be selected to define a Volume Duplicate and unconnected Surfaces will be filtered out 92 Chapter 4 LI By Sweeping to define a Volume by sweeping a selected Surface through a transformation translation rotation mirror or scale A Surface is swept through a translation to create a A Surface is swept through a rotation to create a Hexahedral Volume LI By Splitting Splits a selected Volume by a selected Surface LI By Joining Joins two selected features to form a Volume either a Point to a Surface or a Line to a Surface or two Surfaces The features are joined by straight lines Surface 1 is joined to Point 4 to Surface 1 joined to Line 5 Surface 1 is joined to Surface 2 form a pentahedral to form a hexahedral Two triangular Surfaces joined this way would form a pentahedral Groups of Volumes may be defined by joining two sets of selected Surfaces The first set of Surfaces should be added to selection memory and the second set of surfaces should be selected The Surfaces will pair up equally i e Volumes will be joined according to the order in which the Surfaces were selected The first set of Surfaces in selection memory joins to the first
467. or loadcase name A new tab will appear in the report viewer next to the Preview tab Ol ol e Selecting the Toggle Group Tree E button will permit the viewing of the loadcase feature numbers in the sub reports in a treeview style format as shown on the following image Report 1 my a A S a 5 narn 1 fit 2d Sa fox z Seer Or Preview subreportl2 ld 1 2 Results Chapter 1 5 6 i i Displacement 8 Loadcase D Title Loadcase 1 9 Line 1 10 Dx DY RSLT THE 12 0 0 0 0 0 0 00 13 29 5929E 6 6 5848E 6 30 3167E 6 92 5111E 6 14 15 z E Dx DY RSLT THE 0 445019E 18 0 263404E 3 0 263404E 3 28 9669E 21 2 0 445298E 18 0 261537E 3 0 261587E 3 31 7524E 21 5 DX DY RSLT THE 29 5929E 6 6 5848E 6 30 3167E 6 92 5111E 6 13 7034E 6 0 705137E 3 0 70527E 3 0 224658E 3 Note that it is also possible to create a sub report from a sub report For example when a sub report containing results for a set of loadcases is being viewed a sub report for a particular loadcase or for a particular feature such as a line surface or volume could also be created e To create a sub report from a sub report view double click on the loadcase name as shown in the previous image or feature for which the sub report should be created A new tab will appear in the report viewer next to the previous sub report tab as shown on the following image 384 Chapter 8 i Ss Preview subreport12 1 oe
468. or more of the following data input areas Q Mesh description typical mistakes The aspect ratio of some elements are greater than the recommended limits see the corresponding element section in the Element Reference Manual for further information An ideal value is 1 1 however values up to 1 10 are reasonable Depending on the results required this value may be increased still further a test run would be recommended first This problem is indicated by the WARNING message Unreasonably distorted element The only exception are explicit dynamic elements which really do require aspect ratios of 1 1 Some element shapes are too distorted see the corresponding element section in the Element Reference Manual for further information L Geometric properties typical mistakes Omission of values for any shear area parameters in the geometric properties for beams Omission of values for other important properties such as the torsional constant or thickness Defining incompatible Ist and 2nd moment section properties for beams Q Material properties typical mistakes Different units used to define the nodal coordinates and the material properties Incorrect nonlinear material parameters yield stress and hardening values particularly Inconsistent units throughout the model This would only be of concern for dynamic analyses where SI units are recommended Incorrect definition of orthotropic properties The inequalit
469. order features excluding volumes in the model will be used as a default search area Valid search area configurations are shown below Note The default maximum number of elements that can be used with search areas per grillage bay each four sided framing of a section of slab is 30 In the unlikely event that a higher number is required this can be changed by setting a user defined option in Modeller Contact LUSAS technical support if you wish to do this Rules for Creating Search Areas for Grillages The following general guidelines should be noted when assigning a search area to a grillage model Overhanging elements defined such that only one side Valid of a cell is missing are included in the search area as Paia reas shown In these cases LUSAS automatically closes the cell 210 Elements cannot be included in the search area when they overhang from the same node as shown In this case a dummy Line can be added manually between the 2 overhanging points to close the bay to make the search area valid When closing the bay in this way note that a single null line mesh should be used having one mesh division Cells of more than four edges are automatically subdivided into triangles but overhanging elements are only included if divided by no more than one edge In this case a dummy Line can be added manually between the 2 overhanging points to close the bay to make the search area valid When closing the bay in this w
470. ordinates of the point within the Surface and substituting them into the specified function Surface function variations are only allowed for 3 and 4 sided Surfaces The example shown here defines a variation M using the function max 4 10 u in terms of the Npa u local Surface x direction parametric distance The max function takes two arguments and returns the maximum of both arguments In this case 4 is the maximum value until u exceeds 0 4 Plotting Graphs of Line amp Field Variations Line and Field variations can be evaluated along a specified Line and displayed using the Graph Wizard from the Utilities menu and Line variations can be evaluated alone The number of points at which to sample the variation can be poe specified A factor may be applied to the variation values before the ordinates are calculated This example demonstrates the graphical visualisation of a discontinuous Line interpolation variation 0 Reference paths A reference path defines a route through the model that provides a concept of distance to each point in the model Those distances can be used in the definition of a varying section such that when the section is assigned to lines the path is used to interpret which part of the section is appropriate to each line Bridge engineers refer to this reference path concept as chainage Once created the data that defines the path can be viewed in the Utilities Treeview Like other
471. otation local coordinate with an angle of 90 degrees Notes e The amount of information which may be transferred via the DXF file is limited due to limitations in the DXF file format for example a volume cannot be expressed in standard DXF data 60 Chapter 3 e AutoCAD version 13 uses DXF extended entities for some items LUSAS does not support import of extended entities and will warn to this effect if an AutoCAD version 13 DXF file is detected e Closed surfaces are not translated by LUSAS e Closed polylines and three sided polygon meshes are not translated DXF Export A DXF interface file may be created from LUSAS for use in an external program using the File gt Export menu item LUSAS attributes are converted into their equivalent DXF entity Control over the amount of information exported is provided i e All or Visible features and or mesh may be specified This is valid for both pre processing model files and results files The following parameter is available on the export dialog to control creation of DXF files Q Level Indicator indicates whether Geometry Only Mesh Only or Geometry and Mesh are to be exported The level indicator is only required when a model file is open and features are active When no model is loaded such as during post processing only the mesh is exported Additional options are available to include Volume mesh entities in the export process Only element faces are exported when exporting
472. ould be trimmed from a perpendicular view orientation to achieve a 3D selection A selection may be filtered to include only Geometry Volumes Surfaces Lines Points Mesh Elements Nodes or Annotation by respectively holding down the G V S L P M E N or A key while selecting Element faces may be selected by holding down the F key while selecting LUSAS HPM users only LUSAS Solver can be paused by pressing the Pause key on your keyboard to temporarily free up PC resources if required Press the Esc key to resume Solver 417 Modeller Reference Manual e Errors and warnings reported in the Text Output window can be double clicked to open the Identify Object facility which can be used to locate the referenced items Editing and adding your own tips You can add your own tips by editing the text file named tips txt which is held in the lt LUSAS installation folder gt Programs Config directory 418 Appendix E Appendix E Real Numbers and Expressions in LUSAS Input and Output of Real Numbers in LUSAS The precision of user entered real numbers is preserved both internally within LUSAS Modeller and when re displayed on dialogs All real numbers are displayed in engineering style notation that is in 3 6 9 etc powers of 10 as in 89 6E3 rather than 8 96E4 or 0 896E5 This applies to all text entry fields including the grids used in many places throughout the Modeller user interface For cosmetic numbers that are
473. ove along a specified vector defined by 2 Points or by 2 sets of X Y and Z coordinates In this example vertical and horizontal vectors are l used to restrict movement in those directions Note that _ the vectors are used purely to define a direction Nodes es al can travel along a vector in either direction Geometric Q Rigid Displacements The nodes in the assigned features may be constrained to be rigid the group of nodes may translate and or rotate but their positions relative to one another remain constant Only translational displacements can be constrained using this type of constraint This type of constraint is only valid for small displacements Assigning a constraint of this type to Lines on either side of a gap as in the example shown maintains the underlying undeformed node positions relative to each other as if a rigid block were in place between the structures Q Rigid Links Each rigid link attribute can be used at one location to create a rigid fixity between features that it is assigned to It is similar to the Rigid Displacements constraint type except that rotational freedoms are also constrained to be rigid In the example shown here the end of a beam is rigidly linked to the shell edges around a cylinder The plane containing beam and cylinder end will remain plane throughout the analysis 231 Modeller Reference Manual Q Planar Surface A surface may be constrained to remain plan
474. ow trimmed to a surface boundary Visualisation of Other Composite Model Data To view other composite model data such as lamina thickness skew angles offset layers and fibre volume fractions With a Contours layer in the Treeview right click on Contours On the Contour Results tab select the Composites model entity and select the composite attribute name in the right hand panel The fibre volume fraction and skew angle and any other composite modelling options relevant for the model will appear for selection in the Component combo box N 247 Modeller Reference Manual Setting the Active Composite Layer Composite shell and solid elements have multiple layers laminae of different materials though their EM 1 Stip Lay up thickness The lamina or lamina name on which ee results or orientation axes are to be viewed is pee Llama chosen by setting that lamina active A lamina is ME riirgaw set active by selecting the lamina with the right Sy Composite 1 hand mouse button from the Treeview and picking Set Lamina Active or Set Name Active oom Laminas emm from the context menu A black dot next to a lamina indicates the active lamina If a lamina is set active only results or orientation axes for that lamina in that composite attribute will be displayed If the lamina name is set active results or orientation axes will be displayed for all laminae with that name across all composite attributes When v
475. pe of eccentricity is used when elements share the nodal line as can occur in the analysis of stiffened shells The orientation of the beam axes and hence the orientation of the visualised section is governed by the vertical global axis stated on the Direction Definition dialog The orientation of the beam axes and hence the orientation of the visualised section 1s governed by the vertical global axis stated on the Direction Definition dialog If a thick beam s properties with offsets defined is assigned to a thin beam the Ist and 2nd moments of area will be updated to accommodate the offset as an eccentricity For beams defined using the same standard section rectangular rectangular hollow section circular circular hollow section etc at each beam end the standard LUSAS section property calculator is used to accurately calculate all section property values For beams defined using arbitrary sections of the same section shape at each beam end the standard LUSAS section property calculator is used to calculate the values of A Iyy Izz and Iyz By default the enhanced interpolation method is used to calculate the values of J Asy and Asz but the linear interpolation method is also available The Enhanced interpolation method has been proven to generally produce more accurate section property values than the Linear method For beams defined using arbitrary sections with different section shapes at each beam end by default the Enhanced method
476. port menu item When a file is selected the import process may be controlled by clicking the Advanced button and specifying appropriate parameters LUSAS model geometry cannot currently be exported to a STEP file 67 Modeller Reference Manual STL Import Export STL files are used by Stereolithography software They hold information needed to produce 3D models on Stereolithography machines STL files are imported using the File gt Import menu item When a file is selected the import process may be controlled from the Advanced button by specify the parameters LUSAS Model geometry may be exported to STL format from the File gt Export menu item Notes e STL data defines vertices of triangles that define the shape of a surface 68 Chapter 4 Chapter 4 Model Geometry Introduction There are four geometric feature types in LUSAS L Points define the vertices of the finite element model LI Lines define the edges of the finite element model Combined Lines define edges built from a series of continuous lines LJ Surfaces define external faces or internal construction surfaces of a model LJ Volumes define simple solid components of a model Features are defined hierarchically i e Points define Lines Lines define Surfaces Surfaces define Volumes If higher order features are created using techniques which do not involve lower order features for example by specifying coordinates Modeller will
477. pplied to the line as forces and moments along the line Options available when assigning onto Lines are LJ Exclude All Load beyond the end of the Line default patch load components beyond the end of line will be disregarded and all load components within the search area will be applied to the line with an appropriate force and moment to represent the positions of the loads Q Include Full Load all load components within the search area will be applied to theline with an appropriate force and moment to represent the positions of the loads Patch load components beyond the end of line will be applied to the point at the end of the line with an appropriate force and moment to represent the actual position of the loads Note that when a search area is assigned to a line the search area extends for the length of the line and for an infinite distance perpendicular to the line direction See the diagram that follows or details Extent of Patch Load onto Line S h Ar i Tiisa fori Patch loads not lying on a line but within an assigned search area will be applied to the line as effective forces and moments Loads outside the search area can be either included or excluded If included the applied moments will be computed by using the actual location of the defined loads Point at end of Line at which loads beyond search area will be applied X Ve XN N lt Extent of patch load beyond C end of line Discre
478. pt with a name such as Bending vbs to a folder Then use the User tab to define the action that a particular user defined toolbar button should take when pressed This involves inserting a text string to reference the script that was recorded A typical entry would read Fileopen C LUSAS144 Projects Bending vbs 46 Chapter 2 Customize O TT 2x Toolbars Customise User Toolbars Customise User Categories Buttons 1 Fileopen C LUSAS144 Projects S ectionShrink vbs Test Main i R RO RORDE UR IRO x Define 2 Fileopen C LUSAS144 Projects DistancePoints vbs Test Advanced Define View Utils 3 Fileopen C LUSAS144 Projects LineLength vbs Test Rotate and Zoom Animation Builder i rant 144 Proiects n T Annotation Tools 4 Fi eopen C LUSAS rojects Bending_Mz vbs Test Misia oloctior 5 Fieopen C ALUSAS144 Projects Diagram_Fy vbs Test 6 Fileopen C LUSAS144 Projects DeformedMeshybs Test Select a category then click a button to see its description Drag the button Fileopen CALUSAS 144 Projects Walue_Mx_Peak vbs Test to any toolbar coe 8 Fileopen C LUSAS144 Projects Contour_Mx vbs Test Cancel Apply Help Cancel Apply Help Changing the user defined toolbar button images The default numbered user button images as supplied are held on a single bitmap image that is144 pixels wide and 15 pixels high Each toolbar button image is created in
479. pter is controlled by its Termination parameters Termination may be specified in 3 ways Q Limiting the maximum applied load factor 0 Limiting the maximum number of applied increments Q Limiting the maximum value of a named freedom Where more than one criteria is specified termination will occur on the first criteria to be satisfied Failure to converge within the specified maximum number of iterations will either result in a diagnostic message and termination of the solution or if automatic incrementation is being used a reduction of the applied load increment If required the solution may be continued from an unconverged increment Option 16 17 although the consequences of such an action should be appreciated In addition the solution will be terminated if at the beginning of an increment more than two negative pivots are encountered during the frontal elimination phase Use of Load Curves Load curves are used to simplify the input of load data in situations where the variation of load is known with respect to a certain parameter An example of this could be the dynamic response of a pipe to an increase of pressure over a given period The load curve would consist of the definition of the load and its variation with time 289 Modeller Reference Manual Nonlinear Solution Convergence Criteria The convergence criteria specifies to what extent the numerical iterative procedure has reached the true equilibrium state Th
480. quired using the checkbox provided Additional options are available when applying discrete loads see Assigning Discrete Loads Some loads act in global directions others in local element directions The defined loading value will be assigned as a constant value to all of the nodes elements in the feature unless a variation is applied Variations can be applied to all feature load types except for Beam Distributed loads that have a variation built into the definition Tip If the required loading directions of a global load do not lie in the global axes then a local coordinate may be assigned to the feature to transform the loads to local coordinate directions Notes e Load visualisation can be toggled on and off using the load visualisation button e Load factors of assigned loads can be changed by selecting the Change load factor menu item accessed from the loading name context menu 194 Chapter 6 e In nonlinear and transient analysis feature based loads can be factored using load curves e Consult the Element Reference Manual in order to check that the required loading is available for that particular element Structural Loads Structural loading is feature based and hence it is assigned to the model geometry or to mesh objects in a mesh only model Variations in loading on a feature can be specified using a previously defined variation For information on which load types can be applied to which element types see the Elemen
481. r e An element can only be made invisible if its defining feature is invisible To make a chosen element invisible select the element and then use the Advanced Visibility dialog to make the element invisible by selecting the Also apply to higher order option This makes the selected elements and the defining features invisible without making the unselected elements invisible 36 Chapter 2 Rotating Zooming and Panning A number of tools are available to manipulate the view of the model LI Dynamic rotation is carried out by selecting the dynamic rotate button or by pressing the scroll wheel button and either the left or right mouse button or by holding down the R key while moving the mouse in normal cursor mode The model will be rotated about the centre of the model unless any part of the model is selected in which case the model will rotate about the centre of the selection The model can additionally be rotated around any of the screen axes by pressing additional keys See Rotating the Model LJ Dynamic zoom is carried out by selecting the dynamic zoom button or by scrolling the mouse wheel or by holding down the Z key while moving the cursor in normal cursor more If any part of the model is selected the location of the centre of the selection will remain fixed Q Dynamic pan drag is carried out by selecting the pan button or by depressing the Notes scroll wheel button or holding down the D key while moving the mouse
482. r 2 Modeller Licence Selection LUSAS Modeller E Welcome to LUSAS Please select a licence and then press OK Double click on a licence for more information Product Options Available Bridge plus Bridge Plus 10569 Monline al Dynamics Heat ot Hydratio mn Network feasql lusas com hd Rai amp E spires Bridge plus Bridge Plus 62 74 6270 Nonlinear Dynamics Heat of Hydration Network TECHNICALOI 1 145 day Rail Track Composite Fast Solver ThermalField Bridge LT Bridge LT 6270 Civil amp Structural Autoloader Network TECHNICALOT 1 145 day gt Emulate LT for this session Create shortcut Licence details Refresh T Teaching and training limits for this session Cancel Help When running LUSAS the Modeller licence selection dialog lists all software products that are available for selection along with details of the licenced product options licence type server name number of available licences and the number of days left until expiry Invalid licences those that have already been completely taken by others prior to the display of this dialog or are unavailable for some other reason are greyed out Licences expiring within 14 days are displayed in red The licence selection dialog is always displayed on start up of LUSAS unless it has been disabled by unchecking an option on the Licencing page of the Configuration Utility or unless there is only one lic
483. r Reference Manual Initial Eigenvalue analysis Results at a specific frequency or time step Response calculated at a specified frequency for Response calculated at a specified time for the whole the whole structure structure Frequency Power Spectral Density A Power Spectral Density PSD defines the frequency content of a random loading such as turbulent pressure acting on an aircraft component and are for use in modal random vibration response analysis At present random modal vibration calculations are restricted to single input systems where the loading at all points is fully correlated The value of PSD used in response calculations will be interpolated from a table of frequency PSD values A range of linear and logarithmic interpolation schemes are provided in accordance with typical PSD specifications Dialog input requires Interpolation type options are Linear Linear Log Linear Linear Log Log Log Frequency Amplitude More copious PSD tables may more easily be defined by copying and pasting the data from a text file or spreadsheet Response Spectrum Response spectrums for use in spectral analyses are defined from the IMD loadcase dialog 340 Chapter 8 The value of the frequency used in spectral calculations will be interpolated from a table of frequency amplitude or period amplitude values More copious Response Spectrum tables may more easily be defined by copying and pasting the data from a text file o
484. r mesh pattern on the Surface right 129 Modeller Reference Manual 0 Irregular Surface Meshing The applied boundary discretisation top produces the irregular mesh pattern on the Surface bottom PHD a a Ma gt a as ae SoHo ye s iN LO N AINS AAA ZSA ON EK D gt Z Q NKNZES AVAE AVANAN ATAN a TATAY Se wav arava TISERE sara VANE AZK Default Number of Mesh Divisions If the discretisation has not been specified in the mesh attribute or by using a Line mesh of element type None the Line will be sub divided according to the default number of mesh divisions This is specified on Meshing tab of the File gt Model Properties dialog 130 Chapter 6 Background Grid Meshing Background grid meshing is a method of controlling the size of elements generated during automatic meshing It is generally only used when specification of spacing and stretching parameters at Points is required to grade the mesh pattern locally when irregular surface meshing A background grid is a collection of triangular or tetrahedral shapes which completely encompasses the features to be meshed A Line Surface or Volume mesh is used to define the element type in the usual way and point meshes assigned to the points of the background grid are used to control the element size in the vicinity of each point Finer control is achieved by using more Points in the background g
485. r spreadsheet LJ Frequency Period Displacement Velocity Acceleration The value of the frequency used in spectral calculations is interpolated from the values defined The type of values entered 1 e displacement velocity or acceleration should match the type of support motion which is used to excite the structure For earthquake analyses it is usual to specify Acceleration and to later specify a support motion using acceleration Q Spectral curve damping This value defines the percentage damping inherent in the response spectrum curve itself If the Eurocode or Kapra damping correction formula are specified the spectral response curve is adjusted to the viscous modal damping value specified in the IMD loadcase When using other damping correction formulae the spectral curve is adjusted using only the viscous damping For more details see Theory Manual 341 Modeller Reference Manual Case Study Forced Vibration of a Simply Supported Cantilever Consider the forced vibration of a simply supported cantilever beam The beam is supported at one end and subjected to a uniformly distributed load An eigenvalue analysis is carried out for 9 modes Normalisation with respect to Global mass must be selected when defining the eigen control Calculation of the modal results in the frequency domain is required for Displacement type response for the end node for the Y direction displacement Results are to be calculated over a suitable frequency rang
486. r1 green r2 and blue r3 Starts a colour filled multi sided polygon with number of vertices i1 Real numbers r1 r4 are not used Creates a polygon vertex with x and y coordinate r1 r2 Must be used in conjunction with and appear immediately after code 8 or 9 above Sets current clipping rectangle x1 r1 y1 r2 x2 r3 y2 r4 Defines mutli line text located at x r1 y r2 rotation r3 degrees size r4 mm alignment i1 0 top left 2 top right 6 top centre 8 bottom left 10 bottom right 14 bottom centre 16 middle left 18 middle right 22 middle centre 24 baseline left 26 baseline right 30 baseline centre nLines i2 number of subsequent lines of text Pictures may be saved using the File gt Picture Save menu item Note that views of a LUSAS model can also be saved for use in other applications as BMP JPEG or WMF files using the File gt Picture Save menu item For more information see Printing and Saving Pictures When using the print result wizard the output may be re directed to a Print File A print file has a prn extension The opening and closing of print files is controlled using the Files gt Print File menu item The following facilities are available 95 Modeller Reference Manual Q File gt Print File gt Open The print file is opened by specifying a valid filename LUSAS will prompt for confirmation to proceed if the specified file already exists or if a non default file extension is used
487. rain Q Uniaxial yield stress vs Total Strain Requires input of coordinates at the ends of straight line approximations to the stress strain curve Linear properties specify the slope of the stress strain curve up to yield in terms of a Young s modulus Plastic properties specify the yield stress sy and the hardening data is input as a series of coordinates for example s1 e1 s2 e2 etc LUSAS extrapolates the curve past the last specified point Stress s3 Curve Extrapolation S2 Sl Sy Total Strain Young s ec e3 Modulus Optimised von Mises Model 75 This model represents ductile behaviour of materials that exhibit little volumetric strain for example metals It is especially suitable for explicit dynamics Material Parameters LJ Yield stress The level of stress at which a material is said to start unrecoverable or plastic behaviour Q Heat fraction The fraction of plastic work that is converted into heat energy Only applicable to temperature dependent materials and coupled analyses where the heat 168 Chapter 6 produced due to the rate of generation of plastic work is of interest The value should be between 0 and 1 Hardening von Mises LI Kinematic hardening Plasticity hardening formulation associated with translation as opposed to expansion of the yield surface In the optimised implicit model the direction of plastic flow is evaluated from the stress return path The implic
488. ral Concentrated body force distributed face temperature stress strain and beam loads LI Prescribed used to specify initial displacements velocity or acceleration at a node Note that you can also specify prescribed temperatures Q Discrete loads are used to distribute a given loading pattern such as for a type of vehicle over full or partial areas of the model independent of the model geometry Point and Patch loads are discrete loads also known as general loads Compound discrete loads permit sets of point and patch and compound loads to be defined LJ Thermal loads to describe the temperature or heat input to a thermal analysis Structural Prescribed and Thermal loads are feature based loads that are assigned to the model geometry and are effective over the whole of the feature to which they are assigned Discrete loads are feature independent Further control over how discrete loads are applied is available by using a Search area Assigning Loading Loads are assigned in the same way as other attributes by dragging a defined attribute from the d Treeview onto previously selected features or to mesh objects in a mesh only model When a load is assigned a loadcase and a factor may be specified If a load factor is entered the loadcase name will include this load factor If the load is to be assigned to a new loadcase the new loadcase name may be entered into the loadcase combo and the new loadcase may be set active if re
489. ral vibrations may often be obtained by considering only those freedoms whose contribution is of most significance to the oscillatory structural behaviour This characteristic may be utilised in the condensation of the full discrete model to a reduced system in which the remaining equations adequately encompass the required vibration modes Such a procedure is often termed Guyan reduction and may be used to significantly reduce the overall problem size In a Guyan reduced eigenvalue extraction the stiffness contribution of those freedoms whose inertia effect is considered insignificant designated the slave freedoms are condensed from the system The reduced equation system is therefore dependent on those freedoms remaining designated the master freedoms The resulting eigenvectors of the reduced problem are linear approximations to the true eigenvectors Guyan reduced eigenvalue extraction is specified from the advanced dialog of the eigenvalue control properties Selecting The Master Freedoms Master freedoms may be specified in one of three ways Q Manually Using the attribute Retained Freedoms 294 Chapter 7 Q Automatically Alternatively a specified number of master freedoms may be automatically generated by setting the Eigenvalue properties Advanced button The generated master freedoms will be automatically selected such that the highest stiffness to mass ratios of the associated structural freedoms are used Q Mixed manu
490. ransfers will be read into the current temperature field only initialisation of Reading And Writing Commands To maintain consistency between reading and writing on a specific increment both data reads and writes are performed at the end of the current increment 1 e if data is required for use in the 100th step then it must be read in the 99th step Similarly if data is required to initialise the structural temperature or geometry field it must be read on step zero Data Transfer Between Joints And Links The physical nature of the joint and link elements is essentially different Heat flow can occur between two unconnected bodies via convection and radiation across the intervening medium On the other hand joint elements introduce stiffness against displacement implying a physical connection between two bodies Whilst both may be true simultaneously more usually only one condition will apply In these circumstances it is necessary to introduce dummy joints with springs of zero stiffness or links with zero conductivity to ensure that the appropriate element data is correctly transferred Field Analysis Where a solution is required to Application Cs Filed Variable the quasi harmonic equation a Thermal conduction Temperature field analysis may be performed Seepage flow Hydraulic head The quasi harmonic equation Incompressible flow Stream function defines the behaviour of a variety Soap film Deflection of field problems Some of the El
491. rd manner When combined with the reference path facility more detailed modelling can be done Varying section line attributes assigned to single lines on a model Use of the multiple varying section with the reference path facility enables detailed models of bridges formed of tapered box sections to be created in a very straightforward manner If necessary one geometric multiple varying section line attribute can be defined for a series of multiple varying sections at specified distances that define the complete end to end run of cross sections for a bridge Subsequent assignment of solid or diaphragm sections at supports or mid span can be made to override any previously assigned temporary assignments of voided sections that may have been previously made An example of this follows 161 Modeller Reference Manual Varying section line attributes shown selected assigned to multiple lines on a model with reference to a path Material Properties Every part of a finite element model must be assigned a material property attribute Material attributes are defined from the Attributes gt Materials menu item and then assigned to the required geometry feature or mesh object in a mesh only model Note that not all elements accept all material property types Refer to the Element Reference Manual for full details of valid element material combinations Linear and Nonlinear Material Properties LI Isotropic Orthotropic Defines linear elasti
492. re available are Q Field allowing variations to be defined in terms of the global Cartesian coordinate system variables This form of variation can be used for hydrostatic and wind loading and is applicable to all feature types except Points Variations on volumes are limited to field variations Q Interpolation variations may be applied to Lines and Surfaces The variation is defined by interpolating between values at specified local distances The order of the interpolation may be specified as constant linear quadratic and cubic in either actual local or parametric distance 208 Chapter 6 Q Function variations are expressed as symbolic functions in terms of the parametric coordinates of a feature They can be applied to Lines and Surfaces For Lines the parametric distance is the distance along the Line u and for a Surface the distances are the local parametric u and v coordinates LI Boundary defines values by specifying variations around the Surface boundary Lines Q Grid defines a grid of values in Surface local x and y directions Using Variations Variations are defined from the Utilities menu and are presented in the Treeview Once defined a variation is used by clicking on the additional input button Hin the appropriate edit box on the attribute dialogs This allows each parameter within a single attribute to be varied independently Notes LI It is possible to vary all load types except General Point and
493. re that E gt 1 2 f e For concrete that contains reinforcement distributed fracture will be the dominant fracture state In this case a value for the strain at the end of the tensile softening curve should be entered and G set to zero If no data is available then a value for Of 0 0035 is reasonable to use for most concretes e For unreinforced concrete the strains will tend to localise in crack zones leading to localised fracture The value for must be set to 0 0 and the fracture energy per unit area Gr given a positive value Gp varies with aggregate size but not so much with concrete strength Typical values for various maximum coarse aggregate sizes are 16 mm aggregate G 0 1 N mm 20 mm aggregate Gr 0 13 N mm 32 mm aggregate G 0 16 N mm 173 Modeller Reference Manual Varies with characteristic length w r AS O Damage Evolution Function Softening Curve e Ifthe effective end of the softening curve parameter 0 is set to zero it will be calculated from e0 5Gf Wc ft where Wc is a characteristic length for the element if a finite value is given for e0 Gf will be ignored e The initial position of the yield surface is governed by the value of Zp For most situations in which the degree of triaxial confinement is relatively low a value of between 0 5 and 0 6 is considered appropriate for Z however for higher confinements a lower value of 0 25 is better e The parameter
494. reater than 100 This is to account for contact between bodies that have significantly different material properties See the Theory Manual for more details Suppress initial penetration check The coordinates of all contact nodes that have penetrated prior to the commencement of an analysis are reset back to the closest point on the contacted surface This option should be set if the node resetting is to be suppressed such as when performing an interference fit analysis See the Theory Manual for more details 21 Modeller Reference Manual Solution Optimiser Options When using the standard frontal solver the frontwidth of the problem may be reduced by optimising the order in which the elements are presented to the frontal solver The type of optimiser to be used is selected from an options dialog No optimisation is required when using the fast multi frontal solver For further information see Selecting a Frontal Optimiser LI Solver Options When the type of solver selected is set to Default the fast multi frontal solver will be used if this option is included in the licence agreement This may be overridden by selecting the solver required For further information see Selecting a Solver L Element Options See the Element Reference Manual for details of which elements can be used with these options Assign 6 degrees of freedom to all thick shell element nodes By default this option is on It has the effect of adding a rotationa
495. red to model the changing section depends 268 Chapter 6 upon whether a staged construction analysis will be carried out For the creation of simple models it is possible to assign a multiple varying section line attribute to a single line beam without the use of a reference path but for staged construction analysis where individual lines need to be activated and deactivated the multiple varying section line attribute can be assigned to multiple lines with reference to an associated path See Distance types and methods of assignment for more information Greater than 8 constant section beam elements tobe used along the length of the geometry to whikhthe section has been assigned for small variations in cross section 30 a minimum of 2 elements per ine are required in this case Reference path maa Single geometric line attribute of 3 defined varying al sections assigned to T selecte dines Reference path showing multiple line beams assigned a single multiple varying section for clarity beam lines have been visualised at top of section Reference paths for 3D grid grillage type models For grid grillage models longitudinal beams are comprised of separate line beams often grouped together for ease of manipulation and assignment of properties etc Because the actual profile of the set of grouped members as a whole may vary along the longitudinal beam s length a reference path is used to control the assignment of a multipl
496. reeview and may be changed using the loadcase context menu Non active loadcases are shown with a greyed out icon Inserting a Results Visualisation Layer into the Current Window Layers can be added or removed from the current window using the View gt Drawing Layers menu item A tick is displayed on the menu next to each layer contained in the current window Alternatively with nothing selected right click in the graphics area to display the context menu and add the appropriate layer Another alternative is to select a layer name from the context menu of the Window name in the Treeview The display of layers in the current window can be turned on or off by right clicking on the layer name in the H Treeview and selecting deselecting the On Off option See Using Layers for more information Tips e Use the annotation tools to label the display The annotation toolbar may be displayed using the View gt Toolbars menu item e When comparing different loadcases for the same results type using multiple windows or when creating an animation sequence use a global scale and a global contour range so that scaling and contouring in each frame is relative to the first frame Layer names for results layers H 3 span integral bridge problem mdi Window 1 Contours Diagrams Vectors and Values results layer names as added ffl Mesh to and seen in the Layers ffl Attributes Treeview have the component such ffl Geometry as Mx My
497. required Slidelines may be utilised with higher order elements quadratic variation of displacements but it is necessary to constrain the displacements of the slideline nodes so that they behave in a linear manner LUSAS Modeller will do this automatically The deformation of the slideline surface will therefore be compatible with the slideline algorithm This may however lead to a stiffer solution When defining slidelines for use in implicit dynamics or static analyses low order continuum elements are recommended Explicit dynamics elements only may be utilised to define a slideline surface in an explicit dynamics analysis Do not converge on the residual norm with PDSP loading in a nonlinear analysis This norm uses external forces to normalise which do not exist with PDSP loading Slidelines may be used with automatic solution procedures e g arc length methods The line search and the step reduction algorithms are also applicable 240 Chapter 6 Slideline Options Options relating to slidelines are set from the Attributes tab of the Model Properties dialog Slideline Example Metal Forming Analysis Initial configuration Deformed configuration Composites Composite attributes allow previously defined materials to be collected together to define a laminate or composite lay up Layup definition methods allow for properties to be defined manually for use on solid and shell models and optionally include additional specific va
498. resent dilatant frictional materials that exhibit increasing shear strength with increasing confining stress for example granular soils or rocks The model incorporates isotropic hardening and dilatancy Material Properties Q Initial Cohesion defining the degree of granular bond and a measure of the shear strength LI Friction Angle defining angle of shearing resistance Q Dilation Angle defining magnitude of plastic volume strains Cohesion 1 o tan h f Equivalent Plastic Strain Cohesion Definition for the Non Associated Mohr Coulomb Model Model 65 170 Chapter 6 Friction Angle Er Equivalent Plastic Strain Ep Friction Angle Definition for the Non Associated Mohr Coulomb Model Model 65 Drucker Prager Model 64 The Drucker Prager elasto plastic model see figures below may be used to represent the ductile behaviour of materials which exhibit volumetric plastic strain for example granular materials such as concrete rock and soils The model incorporates isotropic hardening Material Properties Q Initial Cohesion A material property of granular materials such as soils or rocks describing the degree of granular bond and a measure of the shear strength Setting the initial cohesion to zero is not recommended as this could cause numerical instability under certain loading conditions Q Initial Friction angle A material property of granular materials such as cohesive soils and rocks
499. ressive eccentricity of the vertical load on the bending moment diagram In both these cases depending on how large the deflections a man were serious errors could be introduced 1f the effects of nonlinear geometry were neglected 282 Chapter 7 In LUSAS geometric nonlinearity is accounted for using four basic formulations Q Total Lagrangian LI Updated Lagrangian 0 Eulerian LI Co rotational These are defined from the Model Properties gt Solution Nonlinear Options tab All four formulations are valid for arbitrary large deformations In general if rotational degrees of freedom are present rotations must be small for Total Lagrangian An exception to this rule is the Total Lagrangian formulation for thick shell elements where large rotations may be applied Large rotations are allowed for Updated Lagrangian provided that they are small within each load increment or Eulerian The co rotational formulation is unconditionally valid for large rotations and results are generally independent of load step size All formulations are valid for small strains For some elements the Updated Lagrangian formulation is valid for moderately large strains The Eulerian formulation is also generally valid for moderate strains In general the Total Lagrangian is a more robust formulation which is usually able to cope with substantial load increments The Updated Lagrangian and particularly Eulerian formulations generally require smaller load incr
500. riables in either the global Cartesian or a specified local coordinate Coordinates may be Cartesian cylindrical or spherical The expression may be cutoff if desired 259 Modeller Reference Manual Field variations are applicable to all Lines Surfaces and Volumes The value of the variation at any position on the structure will be calculated by substituting the values of the coordinate variables at that position A field variation is defined by specifying a field expression and an optional local coordinate which will be used to specify a coordinate system other than the global Cartesian set variations expressed in terms of the global X coordinate displayed along a Line parallel to the global F A B x X axis The typical field expressions used are shown inthe boxes next to each diagram Fayn For example a field expression in na Cartesian coordinates would typically be F A y and in cylindrical coordinates 10 r tan thetaz These examples show field Coordinate Systems in Field Variations The functions available in the definition of x 0 75 FRAtB x field expressions are listed below The variables used in field expressions are limited to those used in the LPI language Field Variation cage in Local Axis plus the Cartesian cylindrical and spherical System coordinate variable names The coordinate X 0 25 X 0 75 variable names that should be used in a field y expression are dependent o
501. riate break symbol Influence points that no longer lie on nodes or Points as a result of any modifications remain visualised on screen but with a not assigned symbol alongside their name in the Utilities si Treeview Models can be solved with unassigned influences present in the Utilities a Treeview Manipulating Influence Attributes and Influence Point Assignments Influence attributes are listed in the Attributes b Treeview and assigned influences are shown in the Utilities Treeview If influence assignments are visualised the whole model may be re displayed after viewing selected influences by right clicking in the Graphics Window and selecting the All Visible option 2 2 Chapter 6 Writing a Datafile with Influence Attributes Once all influence attributes have been assigned to a model they can be tabulated to a data file using the menu option Files gt LUSAS DataFile LUSAS will automatically identify the datafile to be one that will require an Influence analysis as opposed to a general analysis and as such data file names will be generated from the specified file name and the influence number For example if the specified file name is bridge then files bridgel dat and bridge2 dat will be created for influence lines 1 and 2 respectively An influence analysis can also be run from the Civil or Bridge product menu using the Run Influence Analysis option Viewing Influence Surfaces After carrying out an influence
502. rid definition or by using Line mesh assignments to override the mesh size on specific edges The background grid may be specified explicitly from Points at each vertex or generated automatically Any mesh distortion required may be entered using the point mesh stretching parameters If generated automatically tetrahedral shapes will always be used Modeller Reference Manual Constant Mesh Spacing Same spacing parameters Point meshes are assigned to all Points in background grid ya a a es E a beh Pa LT ia aN We far ERE PTa gt ik val my al weenie is maf EE iy ml are is F iA n i F J a4 S E Tu p D F Notes Varied Mesh Spacing Different spacing parameters Point meshes are assigned to the top Points spacing 7 and the bottom Points spacing 1 in the background grid Background grid meshing requires all Points defining the background grid to have a point mesh assignment e To remove a background grid delete the Background Grid from the a Treeview 132 Chapter 6 Case Study Using Background Grid Meshing 1 With a Surface or Volume already drawn and selected define a background grid by selecting the Utilities gt Background Grids menu item and choosing Enclose Selection Define 1 element in each direction and give the background grid a name Define Point mesh attributes from the Attributes gt Mesh
503. ronym for Microsoft Disk Operating System multi point constraint See constraint equation natural frequency analysis See eigenvalue analysis negative pivot A well conditioned matrix could produce a negative pivot if the system is unstable 1 e passing through a bifurcation or limit point or if the system is not adequately restrained i e a 3D beam in a 2D analysis See also pivot small pivot Newton Cotes A form of numerical integration or quadrature It is often used for through thickness integrals since sampling points are located at the extremes of the range Newton Raphson A nonlinear solution method in which a solution is obtained using an iterative approach based on successive recalculation of the stiffness matrix See also modified Newton Raphson nodal equivalencing See equivalencing 450 Index nodal results Results at node positions Displacements are calculated at nodes whereas stress results are calculated at Gauss points and extrapolated to the nodal positions See also averaged nodal results unaveraged nodal results Gauss point node Finite Elements have their vertices defined by nodes The nodes have degrees of freedom which are the unknowns at the solution stage non associative plasticity A plasticity formulation for granular materials in which the direction of plastic straining is not normal to the yield surface See also associative plasticity plasticity non conservative loading
504. rows above the last defined entry and reverses them to create a symmetric odd numbered arrangement Q Edit Insert and Delete buttons provide the means to select sections from the library create new rows above a selected row and to delete rows from the table 154 Chapter 6 Alignment Q Align all sections to section number align all sections with respect to the specified master section number Use in conjunction with the section visualisation panel Q Vertical and horizontal alignments these govern how tops centres bottoms and sides of adjacent beam sections are set out relative to the master section An option to enter user defined individual offsets is also provided and enables more advanced alignment to be achieved Use the vertical alignment options in conjunction with the section visualisation panel Section offsets explained When sections are specified to define a multiple varying section beam it is important to remember that the master section is the one to which all follower sections are aligned to The offset of each follower section to achieve the desired vertical and horizontal alignment with respect to the master is automatically calculated for each section The offset values seen for follower sections are made up of a value corresponding to the automatically calculated offset required to achieve correct alignment to the master section plus any additional user defined individual offset that may have
505. rticular loadcase e See Geometric Properties for the visualisation of beam cross sections and surface thickness fleshing e See Composites for visualising composites materials Deassigning Attributes Attributes may be deassigned from all or selected features by selecting the attribute in the ob Treeview with the right hand mouse button and picking the Deassign entry from the context menu The menu item entries From Selection or From All may then be chosen to deassign from the items in the current selection or from all the features in the model Unassigned attributes will be denoted with a greyed out bitmap Drawing Attribute Labels Labels are a layer in the amp Treeview To display attribute labels 1 With nothing selected click the right mouse button in the graphics area and choose Labels from the context menu 2 Switch on labels for the chosen attribute type Set Default Assignment Certain attributes mesh geometric material composite can be assigned automatically to all newly created features Default attributes are set by right clicking the attribute in the Treeview then choosing the Set Default entry from the context menu This is useful for models with similar materials or thickness throughout or where the same element is to be applied to all features Attributes that are set as default are displayed with a red box around them in the ob Treeview Meshing a Model Feature based geometry models are defined
506. rties can be saved in the following libraries LI User local for use inside the current project only LI User server for use across all projects Sections selected from a library are added to the b Treeview From there they can be assigned to selected line features on a model For more details on the use of section library items see the Geometric Properties section Adding Additional Sections to the Section Library In addition to sections provided in the geometric beam section library other sections can be added to the library by using Section Property Calculator facilities These are accessed from the Utilities gt Section Property Calculator menu Facilities exist to calculate the properties of standard sections precast beam sections with or without a top slab simple and complex box sections and user defined arbitrary sections that are created in LUSAS Modeller Multiple Varying Sections The multiple varying section dialog is accessed using the Attributes gt Geometric gt Multiple Varying Section menu item It enables pre defined cross sections to be specified at distances for subsequent assignment to a single line or to a series of lines with reference to a pre defined reference path A table is built up specifying the section shapes which define the varying section the interpolation method to be used in order to describe the change of section shape between sections and the alignment method to be used to set out each secti
507. ructures then it may be that the value used is insufficient The solution is typically not overly sensitive to changes in this parameter and therefore any changes tried should be in terms of orders of magnitude 406 Appendix B LI Constraint Equations If constraint equations have been defined in the problem the Sturm sequence check may prove unreliable This is a limitation of the Lagrange multiplier technique used in LUSAS The Solution Did Not Converge Q Check for Warnings or Errors Check the output file for any other warnings or errors There may be diagonal decay or pivot warnings that will contain node and element numbers and help identify any suspect areas of the mesh LI Iteration Vectors Increase the number of starting iteration vectors If any of the modes are close together the default magnitude for this parameter may not be sufficient to allow accurate resolution in their extraction Increasing this parameter is also essential if only requesting a small number of eigenvalues 1 2 Ten iteration vectors would be a reasonable starting value for such a situation This parameter is not used for Lanczos extraction LI Convergence Tolerance The convergence tolerance criteria may be too tight try slackening this criteria This would normally also require an increase in the number of iterations permitted LI Increase Shift If a shift has been used to eliminate rigid body problems when analysing unsupported structures then it m
508. s 1 Inthe Report Treeview select the Results Chapter name and use its context menu to the select Modify menu item which in turn will display the Edit Chapter dialog 2 Use the Order by drop down to select Loadcase Mesh and click OK 3 Inthe Report Treeview select the report name containing data to be exported and use its context menu to select View Report 4 After the report is displayed in the report viewer find the Results Chapter containing data to be exported and double click in the body of the data to create a sub report 5 Ifresults for a particular loadcase is to be exported double click on that loadcase data to create a further sub report 6 Lastly use the Export Report button E to allow selection of the Format and Destination of the results data to be created Example output The images that follow show an example of a sub report created by LUSAS with Loadcase Mesh order and the corresponding results exported to a Microsoft Excel spreadsheet 386 Loadecase 1 Tithe Loadcase 1 DX BY 0 440 10E 106 0 445198E 19 13 70 E 4 0 1265T7E3 EN frame_analysis_outputxls Compatibility Made A B 10 0 2729 5999E 6 3 0 445019E 18 A 0 445298E 18 5 13 7034E 6 6 0 126577E 3 70 0 8729 5929E 6 973 7034E 6 10 0 126577E 3 1 Title DY 0 0 6 5848E 6 0 263404E 3 0 261587E 3 0 705137E 3 0 70508E 3 0 0 6 5848E 6 0 705137E 3 0 70508E 3 9 708E 3
509. s Continuum Damage Models In LUSAS a scalar damage variable is used in the degradation of the elastic modulus matrix This means that the effect of damage is considered to be non directional or isotropic Two LUSAS damage models are available Simo and Oliver together with a facility for a user supplied model A damage analysis can be carried out using any of the elastic material models and the following nonlinear models LJ von Mises L Hill LJ Hoffman Note Creep material properties may be included in a damage analysis See the Solver Reference Manual for further details Composite Matrix Failure Model The composite matrix failure model simulates matrix failure using the Hashin damage criteria The model can only be used with composite solid elements It is defined under the Damage tab on the Material Orthotropic attribute dialog 177 Modeller Reference Manual Material Properties LI Ply tensile strength in fibre direction LI Ply compressive strength in fibre direction LI Ply shear strength measured from a cross ply laminate LI Ply transverse tensile strength normal to fibre direction Q Ply transverse compressive strength See the Solver Reference Manual for further details Viscoelastic Viscoelasticity can be coupled with the linear elastic and non linear plasticity isotropic or orthotropic creep and damage models available in LUSAS The model restricts the viscoelastic effects to the deviatoric component o
510. s Element type LUSAS elements Thick shells TTS3 QTS4 Plane stress TPM3 TPMSE TPK6 TPM6 QPM4 QPM4E QPM4M QPK8 QPM8 continuum Plane strain TNK6 TPN3 TPN3E TPN6 QNK8 QPN4 QPN4E QPN4L QPN4M QPN8 continuum Axisymmetric solid TAX3 TAX3E TAX6 TXK6 QAX4 QAX4E QAX4L QAX4M QAX8 QXK8 continuum Solid continuum TH4 TH4E TH10 TH10K PN6 PN6E PN6L PN12 PN12L PN15 PN15K PN15L HX8 HX8E HX8L HX8M HX16 HX16L HX20 HX20K HX20L Continuum two phase TH10P TPN6P PN12P PN15P HX16P HX20P QPN8P 2D interface IAX4 IAX6 IPN4 IPN6 3D interface IS6 IS8 1S16 1S12 2D rigid surface R2D2 3D rigid surface R3D3 R3D4 235 Modeller Reference Manual Slideline Types There are several different types of slideline LJ Null The slideline attribute is ignored Useful for performing a preliminary check on the model LJ No Friction Used to model contact without friction LJ Friction Used to model contact with friction LI Tied Used to tie different meshes together Q Sliding Used for problems where surfaces are kept in contact but which are free to slide relative to each other The sliding behaviour is frictionless The friction no friction slideline types model the finite relative deformation of contacting bodies in two or three dimensions where the contact is stationary or sliding constant or intermittent The sliding only option is similar but does not permit intermittent contact 1 e the surfaces are
511. s general contact compressional load transfer dynamic impact Q Material Nonlinearity e g plasticity fracture cracking damage creep volumetric crushing rubber material The LUSAS analysis types within which nonlinear geometric and material effects may be incorporated are shown in the following table 281 Modeller Reference Manual Analysis Type Geometric Nonlinearity Material Nonlinearity Static yes yes Dynamic yes yes Thermo mechanical yes yes Creep yes yes Natural Frequency yes yes Eigenvalue Buckling Spectral Response Harmonic Response Fourier Analysis Field or Thermal yes Geometrically Nonlinear Analysis Geometric nonlinearities arise from significant changes in the structural configuration during loading Common examples of geometric nonlinearity are plate structures which develop membrane behaviour or the geometric bifurcation of truss or shell structures The changing application of loads bd or boundary conditions are also geometrically nonlinear effects The figure below shows two simple structural examples which serve as good illustrations of geometrically h nonlinear behaviour For the simply supported beam top the linear solution would predict the familiar simply supported bending moment and zero axial force In reality as the beam deforms its length increases and an axial component of force is introduced For the loaded strut bottom the linear solution would fail to consider the prog
512. s been selected on the dialog displayed for the Combination and envelope options object For further details see Appendix A 325 Modeller Reference Manual Visualising The Results From Combinations And Envelopes Once defined combinations and envelopes may be manipulated in the same way as other loadcases LUSAS will display the results from the active loadcase The active combination or envelope is selected from the Treeview by selecting the appropriate envelope or combination with the mouse clicking the right hand mouse button and selecting the Set Active menu item from the context menu When using smart combinations or envelopes the Set Active menu item will prompt for the primary component on which to base the combination or envelope For an envelope this component will be used to decide which is the maximum or minimum loadcase and for a smart combination which factor to apply to each loadcase When displaying or printing results the values for other components will be the coincident effects For envelopes if no component is specified all components are enveloped independently An active loadcase is identified by a coloured icon in the Treeview Non active loadcases are greyed out For envelopes and smart combinations either the maximum or minimum can be set active Notes e Combinations are only applicable to linear elastic analyses e Envelopes and combinations may be saved in the model file or in a new model file
513. s completely restrained from movement LI Spring Stiffness S the degree of freedom is subjected to a specified spring stiffness Spring stiffness values can be applied uniformly to All nodes meshed on the assigned feature or their values may vary over a feature by applying a variation Alternatively per unit length or per unit area values can be applied The degrees of freedom which may be restrained for any analysis depend on the chosen element type Those applicable for each element are defined in the Element Reference Manual e For structural problems Translation in X Y Z and rotation about X Y Z refer to freedoms along and about the global axes unless a local coordinate is assigned in which cases the axis directions refer to local directions x y z e A hinge loof rotation is a local freedom which refers to rotation about the side of an element Pore pressure is a special freedom type used in two phase elements e For thermal field problems there is only one freedom type temperature or the field variable Using Support Conditions Support attributes are defined from the Attributes menu and assigned in the same way as other attributes by dragging a defined attribute from the ob Treeview onto previously 190 Chapter 6 selected geometric features or to mesh objects in a mesh only model For linear static analyses all support conditions are assigned to the first loadcase For a nonlinear or transient analysis in which
514. s elements by surface normal direction 121 Modeller Reference Manual Note The arrow sizes used for element axes and normals are defined on the Default tab of the Model Properties Visualise Q Joint elements Marks any joint elements in the model with a symbol LI Active mesh Marks the active elements with a symbol LJ Beam end releases Draws the beam end release for elements that use end releases Meshing Points Point mesh attributes are used to assign non structural point mass elements joint elements and mesh spacing parameters to the model Point mass and spacing attributes are assigned to a single Point whereas joint attributes are assigned to pairs of Points The first Point is referred to as the Master the second is the Slave Joint property assignments should be made to the Master Point Meshing Lines Line meshing is carried out by defining a Line mesh attribute and assigning this to a selected Line Line mesh attributes are defined from the Attributes gt Mesh gt Line menu item The number of elements can be specified using either element length or number of divisions Note that when modelling varying cross sections with constant section beam elements care should be taken to ensure that sufficient elements have been assigned Greater than 8 elements should be used for small variations in cross section along the length of the geometry to which the section has been assigned and considerably more elements should be used for
515. s from several load cases may be combined and viewed as an additional load case This additional load case is called a combination Combining loads is only valid for a linear elastic analysis load curve A graphical representation of the variation of a load during an analysis Can be expressed as a load factor in terms of increment or analysis time loading dataset The loading applied to a structure is defined in a loading dataset then assigned to the required feature local A term indicating that an entity is expressed relative to local element axes See also global local axes The axis set used to define an element sign convention local coordinate system May be used to specify the coordinates of a feature or a node in terms of a local Cartesian cylindrical or spherical axis set See also transformed freedom local node segment The node element edge on a slideline surface which is geometrically closest to the node currently being considered in the slideline calculations log life Log plot of cycles to failure over a structure See also fatigue damage lumped mass A diagonalised form of the mass matrix where the mass is lumped at the nodal positions See also consistent mass mapping The numerical process by which quantities for example shape results or stiffness are transferred from one position to another Often associated with isoparametric elements See a so isoparametric elements mass matrix A matrix conta
516. s ordinate with minimum and maximum cut offs at specified Z ordinate values 262 Chapter 6 Case Study Applying Hydrostatic Loading A hydrostatic loading may be modelled using a combination of a field variation and a Structural Face Loading The loading can be considered to be dependent on the depth varying as water density g h y where g is the acceleration due to gravity h is the height of the water above the structure origin and y is the height of the structure Use the following procedure L Define a simple 100 unit square Surface using the Geometry gt Surface gt By Coordinates menu item and entering the following coordinates 0 0 0 100 0 0 100 100 0 and 0 100 0 Define a simple thin shell mesh using the Attributes gt Mesh gt Surface menu item and Assign the mesh to the Surface Define a field variation using the Utilities gt Variation gt Field menu item and specify a function of density g h y where density is the water density 1000 g is acceleration due to gravity 9 81 h is the maximum height of the water above the structure origin 80 and y is the global Cartesian y ordinate This will apply a hydrostatic loading down the depth of the Surface global y axis Enter 1000 9 81 80 y on the dialog To model a water depth of 80 and to avoid negative loading above the surface of the water select a Cut off in Maximum y at 80 Click on the Advanced button and set the maximum second coordinate to
517. s the best chance of negotiating a limit or bifurcation point A load limit point can also be overcome by using prescribed displacement loading LI The system is not adequately restrained for example when using a 3D beam ina 2D analysis Q Mechanism has been excited This is a further possibility when reduced integration is used The use of Option 18 will normally solve this problem If the problem persists continue with the use of the option but refine the mesh further A count of the number of negative pivots is given in the LUSAS log file parameter NSCH Initially NSCH 0 since initially a stable path is assumed When NSCH 1 an unstable point limit or bifurcation has been reached PIVMN will give the value of the minimum pivot at this point Notes e The use of LUSAS Option 62 is not recommended until all other checks have been carried out to ensure model integrity e Before modifying the solution procedure to arc length the checklist given in the section above on small pivots should be checked Zero Pivot Errors LUSAS uses a Gaussian reduction solution technique to solve the finite element equations This technique requires the structure stiffness matrix to be non singular This means that for static analyses the structure or any components of the structure must not permit any rigid body displacements or rotations Failure to comply with this criterion will result in a zero pivot message 403 Modeller Reference Ma
518. s the product options the licence version the Key ID and the licence expiry date can be viewed Selecting a licence that is invalid and clicking the licence details button will yield extra details as to why the license in unavailable Refresh Refresh simply updates the numbers of licences available Emulating LT Behaviour When Emulate LT is selected it restricts the user interface to that of an LT licence even though the selected licence may be a standard or plus licence This may be of use when training staff who are new to LUSAS Teaching and training limits When Teaching and training limits is selected no licence is taken LUSAS can be used as normal for this session only but with the restricted model size node element and loadcase limits of the Teaching and Training version Creating a New Model The New Model dialog is displayed every time a new model is to be created The dialog enables the model file to be named and located in a selected project folder and for initial model set up information to be specified 14 Chapter 2 The model title job number units and designated vertical axis are also defined The style of user interface can be also set dependent upon licence key options This simplifies the user interface and also defines the class of model to be created The model title and the style of user interface can be subsequently modified on the General tab of the Model Properties dialog accessed via the Fil
519. sation 246 Fibre locations 148 358 field loads 217 file types 49 50 52 53 54 55 Fixing Mesh Problems 136 FLD loading 196 fleshing 151 Flux 217 foam material model 182 Fourier expansion 365 Fourier analysis 307 Fourier results 333 365 frequency response 339 Friction Pendulum 187 Frictional slideline 234 frontal solver 309 function 259 Functions supported 419 G general loads 201 geometric Attributes 148 Geometric Attributes 151 geometric nonlinearity 282 geometric properties 149 Geometric Properties 147 geometry 69 geometry orientation 111 getting help 12 Modeller Reference Manual gnl 282 graph wizard 354 365 graphing 365 groups 33 Guyan reduction analysis 219 294 HA HB loading 201 Hashin failure contours 335 Hashin material model 177 heat of hydration 164 heat transfer 227 Heat transfer 227 help 10 hexahedral 92 highway load 201 Hill yield criteria 167 Hoffman yield criteria 167 holes 86 hollow volume 95 home view 37 hook contact 190 hyper elasticity 179 IFFLR 335 IGES 62 IMD 299 335 365 impact analysis 234 302 Import files 57 59 options 57 59 Influence Attributes 271 272 476 Initial Acceleration 199 Initial Velocity 199 Integration options 23 interactive modal dynamics 335 interface elements 137 141 interface files 56 interface material models 352 internal heat generation 217 inverse i
520. sed to limit the application of load to one of these multiple intersections Restricting the area of application of discrete loads allows the same load attributes to be used to apply loads to different parts of the model LL Speed Improvement the speed of calculation of equivalent nodal loads will be increased by cutting down the number of features considered in the calculation Search areas are automatically created and used by the prestress wizards to define the target to be loaded 209 Modeller Reference Manual In the example shown a multiple span grillage os 1 Span 2 Loaded Unloaded structure is defined with Span 1 as the search area A discrete Patch load indicated by the grey shaded HA f Load region in the upper diagram is applied across the whole structure Span 1 and 2 The area of the structure coinciding with both the Search Area and the patch load will take the load as shown in the lower diagram Tip Search areas should be used if the model is three dimensional and discrete loads are applied as for example for box section or cellular construction decks Defining and Assigning Search Areas Search areas are defined from the Attributes menu then assigned to the required Lines or Surfaces Control of loads lying outside the search area is available when the load is assigned see Assigning Discrete Loads If a search area is not specified when the load is assigned all of the highest
521. sferred from LUSAS to Modeller If no material properties are detected in the LUSAS mys file then dummy material properties are set up and a warning is issued Materials can be used in LMS to group common elements together The dummy properties allow the other model description entities element topology to be read by the LMS parser Q Element Properties mdl file The LMS element properties supported are PBAR STIFF PMASS BEAMG and THICKV The corresponding Modeller geometric properties are mapped into the expected LMS format Supported Modeller property types are as follows Bar Link Beam Membrane Plate Shell Beam and joint eccentricities are ignored Checks for unsupported element properties are made and a warning is issued if any are found Unsupported element properties are not output Q Element Properties mys file Modeller geometric properties from the mys file are transferred and output into the LMS neutral file The same constraints as for the mdl file apply LI Element Topology Elements are output in element type order Material properties must be specified for all elements but LMS element properties for solid elements are optional Checks for unsupported elements are made and a warning is issued with the unsupported elements not written to the neutral file Beam elements which have end freedoms released are output to the neutral file but the node freedoms are not transferred as they may not be valid for all connections to a node
522. sh will now be adopted because the line divisions on the Combined Line match those on the opposite Line Irregular Mesh Regular Mesh Using Combined Lines A regular Surface mesh using Plane Stress The lines on the right hand side are used Quadrilateral Linear elements is assigned to to define a Combined Line A remesh the Surface with the resulting mesh shown occurs because the surface has been An irregular mesh is used as surface does redefined and a regular mesh is generated not have 3 or 4 sides because the surface is now defined with 3 Lines and 1 Combined Line 84 Chapter 4 Surfaces Surfaces define the faces of the model The Surface types are LI Regular defined by 3 or 4 Lines Q Irregular defined by 5 or more Lines Note For meshing purposes an irregular surface can be considered to be a regular surface using Combined Lines Surface Definition Commands The following commands are for defining Surfaces directly LI By Coordinates Defines a Surface by entering a list of X Y and Z coordinates Z is optional If a non Cartesian local coordinate system is in use the coordinates are specified in the coordinate system of that local coordinate Coordinates can be entered using global default or local coordinate systems LI By Cursor Allows definition of a series of flat rectangular Surfaces on the screen with the cursor The Surfaces can snap to a grid in the XY YZ or XZ plane The out of plane ordinate can be speci
523. sidered as a starting position for stress for a nonlinear analysis Failure to ensure that the residual stresses are in equilibrium will result in an incorrect solution There is no concept of residual strains and therefore when the residual button is chosen a reduced number of components are presented Refer to the individual element descriptions in the Element Reference Manual for full details of the initial stress and strain and residual stress components LUSAS Modeller will automatically write an appropriate initial stress and strain or residual stress type to the datafile when a solve is requested See the Solver Manual for more detailed information regarding the tabulation of initial stresses and strains and residual stresses in LUSAS datafiles Internal Beam Loads ELDS The Internal Beam Point load is a point load applied to lines in the local or global direction The distance may be defined as either parametric 0 to 1 or actual distance The distance from the start of the line to the point load is defined along with the point load values Several point loads may be defined in one load attribute if required End Distance The Internal Beam Distributed load is a lt distributed load applied to lines in the local global or projected direction For local and global loading the distance maybe defined as either parametric 0 to 1 or actual distance Only actual _ distance is permissible for projected loading The C Z dista
524. signed to the Surface boundary Lines Note the direction of the axes of the local element faces Where a loaded Line or Surface feature is common to two or more higher order features it is possible to specify to which higher order feature elements the load is assigned See the Element Reference Manual for details of element face directions Local Distributed Load UDL Defines a load per unit length or area for line or surface elements in the local element directions Typically local distributed loading is applied to beam elements and shell faces An example of a local distributed load is internal pressure loading For beam elements when the element type permits uniformly Distributed Load will be written to the LUSAS data file as Beam Element Loading ELDS 196 Chapter 6 Temperature Load TEMP TMPE Nodal and Element temperatures define the LUSAS Solver TEMP and TMPE load types respectively These loads apply temperature differences on a nodal and element basis Temperature gradients in X Y and Z directions may also be input This load type can be used in conjunction with temperature dependent material properties to activate a different set of properties at a specified point in the analysis The thermal expansion coefficient is normally set to zero in this case Notes e Nodal temperatures apply to all elements connected to that node except joints in which temperature loading is invoked using Option 119 e Elemental
525. sing the same shape functions See also shape functions mapping isotropic A term indicating that the material properties are the same in all directions See a so orthotropic anisotropic iteration A step within a load increment where the analysis solver attempts to converge to an acceptable solution See also increment joint element An element with translational and rotational stiffness which may have initial gaps contact properties and other nonlinear behaviour Also known as a spring element Kbyte K Signifies a quantity memory equal to 2 raised to the power 10 bytes which is equal to 1024 kinematic Plasticity hardening formulation associated with translation as opposed to expansion of the yield surface Kirchhoff beam Thin beam which ignores shear deformation See also engineering beam numerically integrated beam knife edge loads A special case of discrete patch load with two or three defining points to model a straight or curved knife edge load See also discrete point and patch loads label A label can be drawn on the screen to show feature dataset numbers or the dataset numbers of attributes assigned to them See also feature attribute assign 445 Modeller Reference Manual laminate An individual layer of a composite material See also layer composite properties large rotation A geometrically nonlinear analysis for beam plate or shell elements where the rotational degrees of freedom u
526. sis Types 1 Check the first natural frequency against hand calculation 2 Check of convergence of the eigenvalue extraction algorithm Non 4inear Analysis Types 1 Check convergence of the non linear analysis 315 Modeller Reference Manual 316 Chapter 8 Chapter 8 Viewing the Results Introduction This section deals with procedures for results processing It covers manipulation of results files selection of the correct results type and loadcase and differences between results viewing coordinate systems LI Results Processing provides an overview of results processing LI Results Files covers manipulation of results files LI Results Selection covers selection of the active loadcase a fibre location and a composite layer It outlines all the different results types available during post processing LI Results Transformation presents the options for transforming results Results Processing Results processing also known as post processing is the manipulation and visualisation of the results produced from an analysis Prior to visualising and extracting results further calculations may be carried out to create or assemble results or the results model can be manipulated to create results at particular model locations for a particular results viewing use Depending on the type of analysis any of the following results calculation manipulation or viewing can be carried out 317 Modeller Reference Manual
527. site It is often referred to as the edge effect because it is most common at the free edges of the structure delimiter A character that marks the beginning or end of a unit of data density A measure of the mass per unit volume of a structure Also known as mass density See also mesh density departure from linearity Achieved by using a hierarchical degree of freedom at a central node which represents the relative displacement of the two end nodes device A piece of hardware that performs a specific function For example a printer dialog box A box displayed on the computer screen to accept data input from the user See also OK button apply button diagonal decay Is an indication of poor conditioning It indicates that round off error during the solution has become significant which may lead to inaccuracies in predicted results A poorly conditioned stiffness matrix is the result of a large variation in magnitude of the diagonal terms This could be caused by large stiff elements being connected to small less stiff elements or elements with highly disparate stiffnesses diffuse radiation Radiative heat emitted equally in all directions from the source point direct integration The equations of motion including mass and damping effects are integrated in the time domain The solution is progressed at discrete time points the time interval between each being the time step A so known as step by step dynamics 432 I
528. son gt SSS viewing results on groups see Plotting Results for Advanced Visibility Groups Results Plots Draw Axes Delete Notes Select Members Deselect Members e The mesh and nodes on the slice are displayed using the mesh layer Print Properties properties Print Local Forces Properties e The slice local axes and origin are displayed and moved from the slice properties accessed from the slice context menu e The resultant local forces on the slice and the slice properties may be printed from the slice context menu e Groups created from slice sectioning a 3D model cannot currently be retained when a model is saved Graph Through 2D Arbitrary line sections may be taken through any surface model or on a slice cut through a three dimensional solid model The process of cutting a slice will generate two graph datasets the first containing the distance along the line section and the second containing the specified results along the line The graph datasets are plotted automatically using the Graph Wizard Graph datasets are stored in the Utilities oi Treeview By default line sections may be cut at arbitrary positions through the model using the cursor Lines can also be defined to start and finish at points located on an underlying grid When cutting a line section through the model an option to create an annotation line is provided This may be used later for repeating the cut if a graph along the same l
529. specific heat OPTION 105 is used This is specified in the Model Properties gt Solution gt Element Options dialog by choosing the lumped mass option For heat of hydration analysis where internal heat is generated by the chemical reaction between cement and water as concrete hardens additional thermal options such as exotherm type cement type and timescale units can be set LUSAS Solver can model temperature dependent properties but this needs to be defined in the Solver datafile See the Solver Reference Manual for further details 166 Chapter 6 Stress Potential von Mises Hill Hoffman The use of nonlinear material properties applicable to a general multi axial stress state requires the specification of yield stresses in each direction of the stress space when defining the yield surface see the LUSAS Theory Manual Notes e The yield surface must be defined in full irrespective of the type of analysis undertaken This means that none of the stresses defining the yield surface can be set to zero For example in a plane stress analysis the out of plane direct stress Ozz must be given a value which physically represents the model to be analysed e The stresses defining the yield surface in both tension and compression for the Hoffman potential must be positive Material Properties LJ Yield stress The level of stress at which a material is said to start unrecoverable or plastic behaviour Q Heat fraction The fractio
530. splayed when editing the properties of an existing loadcase e By selecting the Gravity menu item from the context menu for an individual loadcase e By selecting the Add Gravity menu item from the context menu of the Structural folder in the Loadcase Treeview This effectively sets gravity loading to be on for all structural loadcases in the Treeview regardless of whether they previously had gravity loading added or not For the special case of loadcases having nonlinear controls gravity loading is only added to those loadcases defined with Manual incrementation and not to loadcases defined with Automatic incrementation because the latter inherit the properties of the preceding defined Manual increment Note Gravity loading is defined in accordance with the vertical axis direction that was specified either initially on the New Model dialog or subsequently on the Vertical Axis dialog accessed using the Utilities gt Vertical Axis menu item No visualisation of gravity loading on the model is provided for gravity defined as a property of a loadcase However the general loadcase icon will change to include a loading arrow symbol to show that gravity is included for a particular loadcase Manipulating Loadcases General loadcase editing commands are available from the context menu that is activated by right clicking on a loadcase in the Treeview The following commands are available LI Copy Copies the selected loadcase including a
531. ssigned attributes Graphing of results Animation sequences Printing results to the screen or a file Generating a Report Manipulating the model Plotting results forgroups Results on a section through the Slideline results processing Thermal surface results processing Chapter 8 Results Files When an analysis is performed by LUSAS Solver a results file will be created For historical reasons this has a mys extension By default the results file is automatically loaded into LUSAS Modeller on top of the model file after LUSAS Solver has been run The information in the results file is stored in a binary form and may only be accessed using LUSAS Modeller The results file will contain the results of the analysis and sufficient model information to process the results Full details of the finite element mesh nodes and elements material and geometric property numbers support positions and equivalent nodal loads are stored in the results file Opening Results Files Results may be loaded on top of a model or used stand alone Results are usually loaded automatically when analysis is carried out and are offered for opening if a results file of the same name as a model file is detected when a model is opened Results files may also be opened in isolation manually using the File gt Open menu item 0 Load results on top of current model Results are normally processed by reading l amp Q If the results file on top of an exi
532. ssigned to a feature can additionally be chosen to be ignored as a separate option LI By point in selection memory A Point previously added to selection memory is used to define the xy plane LI By specified local coordinates The element axes are defined using a previously defined Local Coordinate For Joint element assignments only the order of the features selected determines the Master and Slave Joint elements are orientated from the Master to the Slave To swap the Master and the Slave deselect the Mesh from Master to Slave option 139 Modeller Reference Manual Case Study Joint Interface Mesh 2D ji In this example Line 2 is placed in selection kanai I memory Slave and a Line joint mesh oe C EERE EX attribute with 6 divisions is assigned to Line s 1 Master Joints are created automatically to tie the Lines together with an interface joint mesh Note The unmerge facility allows coincident features to be created from a single feature and also allows a feature to be set as Unmergable so it will not be accidentally merged back with another coincident feature See Merging and Unmerging for more details Case Study Cylindrical Joint Interface Mesh 3D Master In this example a Surface joint mesh is R Slave assigned to Surfaces between two concentric voin cylinders Cylindrical axes are defined for the joint properties using a local coor
533. st be meshed using an irregular mesh The user interface to enable the creation of hollow volumes may be invoked from the Advanced Dialog of the Geometry Properties dialog This option is automatically invoked when geometry is imported from CAD When this option is chosen the volume definition tools will try to automatically create a solid volume as normal However if this process fails a further attempt will be made to create a closed hollow volume from the selected surfaces using the defined closure tolerance 95 Modeller Reference Manual Open hollow Volumes can only be created via the Geometry gt Volume gt Hollow Volume gt Create menu item Surfaces may be added or removed from an open hollow volume definition using the Geometry gt Volume gt Hollow Volume gt Add and Geometry gt Volume gt Hollow Volume gt Remove menu items Once a hollow volume has been defined its status open or closed can be determined from its properties dialog In some cases an open hollow volume may be changed to a closed hollow volume by simply increasing the closure tolerance on the volume properties dialog When meshing a closed hollow volume any nodes closer together than the volume s node merge tolerance defined on the volume properties dialog are merged For closed hollow volumes this defaults to the volume closure tolerance Shape Wizard The shape wizard defines analytical shapes which may orientated with a local coordinate system and position
534. sting model S E frame_2d md file This enables the visibility of the model oy to be controlled by the assigned attributes GIN TLoadcase 1 i Supports and all model data including group Seed information is present to aid results Loadng manipulation Supports and loading attributes UE a as assigned for each loadcase can be seen S E Loading When results are loaded on top of a model P PERTE i daa file only the results are loaded from the mys Combination and envelope options file Multiple results files may be loaded when accessing results from a number of analyses at the same time Subsequent results files may be loaded on top of an existing model or an existing results file Jea The Treeview above shows a results file loaded on top of a model file 319 Modeller Reference Manual LI Results Only When results files are opened stand alone the mesh definition and all of the results are i Q lZ read from the mys file This method is used B E Loadcases NW 1 Loadcase 1 1 2 Loadcase 2 when access to model information such as feature definitions or group names is not required or is not available for results processing Subsequent results may be loaded on top of the first results file loaded The Treeview above shows the listing obtained for the same analysis when only the result file is loaded 320 Chapter 8 Results Selection Setting the Active Loadcase The active loadcase is the
535. sults file on every time step or load increment 52 Chapter 3 The information in a Solver results file is stored in a compressed binary format and may only be accessed using LUSAS Modeller The results file will contain the results of the analysis and sufficient model information to process the results Full details of the finite element mesh nodes and elements material and geometric property numbers support positions and equivalent nodal loads are stored in the results file so that results processing can be carried out without a model file if desired To access results from the LUSAS analysis results files can be opened in a similar way to model files Modeller Results Files A Modeller results file contains loadcase combination and envelope component results that are calculated by LUSAS Modeller Modeller results files have a mrs extension and are saved whenever the model is saved A Modeller results file speeds up the assembly of the selected results within LUSAS Modeller since the component results are only calculated once for the selected combination and envelope results components This means that when setting each combination or envelope active for viewing results the software does not have to re calculate the results for that results component However selecting a combination or envelope result component that is not pre calculated will cause the results for all envelopes of envelopes and combinations to be re calculated T
536. system generated like the current zoom factor only a sensible number of significant figures is shown This does not alter the precision stored which will always be the maximum allowed by the operating system Expressions and Functions Supported Expressions may be entered anywhere in LUSAS Modeller where numbers may be input For example in point definition it is possible to enter 3 10 4 6 and 5 1 as valid co ordinates All arithmetic operators including braces are available as well as the standard trigonometry functions sin cos log etc This facility is available in all text entry fields throughout the Modeller user interface The following functions are also supported Arithmetic A A A B A B A B A B A B ceil A floor A abs A max A B min A B pow val exp mod val div 419 Modeller Reference Manual Trigonometric Sin cos tan asin acos atan sinh cosh tanh sind cosd tand asind acosd atand atan2 atan2d Mathematical exp log 1logl10 sqrt Logical A gt B A lt B A B not A and A B or A B DoolEq A B boolNE A B gt A B ge A B 1t A B le A B eq A B ne A B if condition then else Other Radians angle Converts an angle entered in degrees into an angle in radians Degrees angle Converts an angle entered in radians into an angle in degrees 420 Glossary Glossary abscissa The x axis of a graph See also ordinate graph dataset accelerat
537. t Line gt From Mesh Geometry gt Surface gt From Mesh Geometry gt Volume gt From Mesh menu items LJ Point creates Points from nodes L Line creates Points from nodes and Lines from beam elements surface and volume element edges LI Surface creates Points from nodes Lines from beam elements and Surfaces from surface elements and volume element faces 98 Chapter 4 L Volume creates Points from nodes Lines from beam elements Surfaces from surface elements and Volumes from volume elements To convert from mesh the results database must be saved as an model file with access for writing prior to conversion Firstly open the mys using the menu item File gt Open then save as a model file using File gt Save As Select the elements you wish to convert to geometry and pick the appropriate From Mesh menu item Notes e No attributes will be converted e When converting to Volumes to resulting Volumes may be coalesced by removing the internal Surfaces e The conversion commands always create new features and cannot be used to edit existing features e Quadratic element edges with 3 nodes are converted to spline Lines with an exact match using the end node positions A Point is defined at the mid side node position but is not used in the Line definition Moving and Copying Geometry Geometry may be moved or copied to new positions using transformations Compound transformations may be used in which a series of transformat
538. t Reference Manual Concentrated Load CL Global Z A Concentrated Load defines concentrated Sn Line X load on Point with force and moment loads in global or Transformed Freedoms transformed directions A Concentrated Load is applied per node of the underlying feature onto which the load attribute is assigned A Concentrated Load is therefore normally only used to assign a load to a point as the total applied load would otherwise be dependent on the mesh density of each feature assigned to Global X on Line Concentrated loads are defined relative to the nodal coordinate system If the required loading directions of a global load do not lie in the global axes then a local coordinate may be assigned to the feature to transform the loads to local coordinate directions Concentrated loads can be applied in cylindrical coordinates for Fourier elements by setting the option on the Attributes tab of the Model Properties dialog Body Force CBF A Body Force defines an acceleration or force per unit volume loading in global directions A typical example of body force loading is self weight which requires the specification of gravitational acceleration and mass density in the material properties By default Body Forces define accelerations but an option on the Attributes tab of the Model Properties dialog can be set so that Body Forces define a force per unit volume 195 Modeller Reference Manual Note that gravity l
539. t a node is obtained by multiplying the normal penetration with the contact stiffness Coulomb s law of friction also uses gap forces To check the application of the law the normal and tangential gap forces should be compared Contact forces The normal and tangential gap forces at each slideline node are distributed across both slideline surfaces These forces are assembled together and kept in the local directions normal and tangential to the contact surfaces to give the Contact Forces The contact pressures and stresses are based on these forces Contact Stresses This category contains results for the contact pressure normal to the surface and the contact stresses tangential to the surface at each node Section Results This category contains generic contact results It includes the status of each node as to whether it is in contact or out of contact the normal penetration for each contacted node the contact stiffness the nodal contact area and the zonal contact distance Graphing Slideline Results To graph slideline results the nes iad of interest must be set visible from the group context menu in the Group Treeview El For two dimensional analyses the graph wizard can be used to generate the variation of a particular slideline result along the slideline surface The variation along the surface can either be graphed against distance or angle For three dimensional analyses the slideline results are graphed in the same manner as
540. t define any surfaces Use domain space trimming curves in preference to model spacing trimming curves Locks the mesh following import to ensure it is not changed unintentionally If selected fills in any missing data to create a solid volume Removes similar surfaces from adjoining volumes to simplify the model Create named groups for features in the data file having the same material property Maximum number of groups permitted to be created from material property types Merges geometry within the general specified merge tolerance Facets containing lines of less than this specified length will be ignored Facets containing lines of less than this specified length will be ignored Scaling factor applied to all entities before translation Minimum allowable radius of curvature to line length ratio in surface trimming Import terminate after specified number of error 0 indicates no limit List of entity type numbers to ignore if checked entities of these type numbers will not be translated unless they define entities that are to be translated 58 Default False False False True True True True False False False True False 500 True False False 1 0 1 Ignore 106 copious data and 108 plane surface Chapter 3 Drawing layers to Allows selection of named layers when importing DXF or None process IGES data Importing Mesh Data Mesh only models can b
541. t if selected For Arcs the default i ee a direction is assumed to lie in the l plane of the Arc Volumes About Volume Features Volumes define the solid geometry of the model and come in two forms Q Solid Volumes are defined by a number of connected Surfaces These are recognised by the geometry engine which allows Boolean operations to be performed Solid Volumes are the default form of Volume and are created when geometry is defined in Modeller LI Hollow Volumes are defined by a number of disconnected Surfaces These are not recognised by the geometry engine Hollow Volumes are usually only of use when the geometry has been imported from CAD For meshing purposes volumes may be split into the following categories Q Regular volumes may be defined as Tetrahedral 4 sided volume with all faces defined by triangular surfaces Pentahedral 5 sided prism with top and bottom faces defined by triangular surfaces and side faces defined by quadrilateral surfaces Hexahedral 6 sided cuboid with all faces defined by quadrilateral surfaces L Swept Irregular are defined by 2 identical irregular Surfaces joined at equivalent positions on the boundaries by quadrilateral Surfaces The Lines joining the two irregular Surfaces must be either straight Lines or arcs with a common centre Q Irregular are defined by any number and type of surface but can only be meshed with tetrahedral elements Defining Volumes The following commands are f
542. t integration through the element thickness Notes e Angle of orthotropy is relative to the reference axis degrees e The element reference axes may be local or global see Local Axes in the Element Reference Manual for the proposed element type If the angle of orthotropy is set to zero the anisotropy coincides with the reference axes See the Solver Reference Manual for further details Thermal Material Thermal material properties are used to define the thermal behaviour of a material when using Thermal Field elements The thermal properties describe the way in which heat flows Heat may be transferred through conduction convection or radiation For linear steady state heat transfer problems only the conductivity needs to be specified For materials in which the conductivity is constant in all directions isotropic material input should be used When the conductivity varies in different directions orthotropic material input should be used The direction of orthotropy is defined relative to any local coordinate systems For transient thermal analysis the specific heat capacity is also required It should be noted that within LUSAS a specific heat coefficient is used The specific heat coefficient is computed by multiplying the specific heat capacity by the density If phase change is to be modelled the enthalpy must be specified Two phase changes models are available When carrying out a phase change it is recommended that lumped
543. t position to visualise the coordinate system and provide control of the style General L View name is the name of the current window LJ Show Rulers Shows or hides the X Y Z axis rulers of the current window L Selection tolerance Sets how close the cursor has to be to a feature to be able to select it Colours LUSAS uses standard Microsoft Windows colours to define the screen colours by default By deselecting the Use Windows colours option the following colours can be changed LI Background colour Sets the window background colour LI Selection Pen Sets the pen colour used to draw model feature when they are selected LI Selection memory Pen Sets the pen colour used to draw model features when they are in selection memory View Q Scale to fit window page Option set by the resize button to ensure the model fits the screen area Q Scale Option enables the model to be scaled WL Origin position Defines the origin of the model 43 Modeller Reference Manual LI Rotation Vector An equivalent eye position coordinate Entering 0 0 1 views the model from the Z axis and 1 2 3 gives a three dimensional view LJ Rotation increment Sets the rotation increment used for incremental rotation LI Triangle sort Defines the triangular sort algorithm to use when shading GDI drivers only LI Save View Saves the current view including the window properties pen library colour map and window layers When a view is loaded into
544. t this option if the slideline type is to change during the analysis The slideline can be changed from one type to being any other type at any stage in the analysis For example the slideline can be tied to begin with and then released at a later stage If this option is not selected the initial slideline type is used throughout the analysis Type after change The slideline type after change e g Friction 238 Chapter 6 Changes at loadcase The loadcase at which the slideline type should change from the initial setting to the changed setting e g Tied to Friction Rigid type To model contact with rigid bodies rigid slideline surfaces are available Rigid surfaces can be assigned to valid structural elements as well as to special rigid surface elements R2D2 R3D3 and R3D4 The latter are recommended for modelling rigid bodies since they remove the need for defining structural elements and hence speed up the solution All nodes on a rigid surface need to be completely restrained Since rigid surfaces cannot contact each other only one slideline surface can be defined as rigid master or slave Number of passes Slidelines involve a two pass procedure in general in which contact on both slideline surfaces is processed With rigid surfaces however a one pass procedure is available that only checks the penetration of the deformable surface into the rigid surface If the one pass procedure is selected it is recommended that
545. tbeentccehenssassbedciseunsceceeetesiossteecestubedeieceteusis 375 VIGWING a REDON i e ee ele hae eee ee eee A ae nee ea 382 Exporting REDOM Date saiiiscccateaetaradwaacaiuiskan cata ddeieaussidanunticeuenualecndeetdarassacciuanecananuubbeauduns 385 Appendix A Smart Combination Examples cccccccccccccccceeeeeeeeeeeeeeeeeeeeeaeeeaaaaeaeaaeeeeeeaeaeaas 389 Smart Combinatlon Examples sssicssascccs cis ccequnvescacs eps scevsasssvacsavtinetuavecsacsapnasecnneniacsavaesatees 389 Appendix B LUSAS Solver Trouble SHOOting cccccccccccccceeeeeeeeeeeeeeeeeaeeeeeeaaeaeeeeeeeeeeaaaas 399 LUSAS Solver Troubleshooting is iissssdscecee cect ssetsdd sees eoceicceducedesteeeds cesducacoec eden cesicedees eens 399 Appendix C Keyboard Shortcuts 12 icnccaciccccescidccce tense tece ce ecceeneetbede cetacean edeesbeencctcedeenacbicdaaved 409 Keyboard Shortcuts X saiae ine ne ae nen 409 Model Viewing Shortcuts cccceeeeeeeeeeeeeeeeeeeeeeeeeeeeesneeeeeeeeeaaaaeeeeeeeeeasaeeeeseeeeasaeeeeseeneeneeeees 411 Usef l Windows SNOFICUUS ic cscsesis3 ch pessivesnescteespnansiwasnenaiedsnensnnesnesaddenndnsssesnanaindsaenapneaxezeiness 413 Appendix D Tip Of the Day ooreen hues meses ardent a aaa daaa Ea ena 415 Tip OF MG Day caniin a aa eaaa a a aa a aea aa Eea aaa Dea 415 Appendix E Real Numbers and Expressions in LUSAS sssseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeenes 419 Input and Output of Real Numbers in LUSAG ccccceeeeeeeeeee
546. tch load components outside the search area will be applied to the nearest elements in the volume 216 Chapter 6 Thermal Loading Thermal loading is feature based and hence it is assigned to the model geometry Variations in loading on a feature can be specified using a previously defined variation For information on which load types can be applied to which element types see the Element Reference Manual Thermal loading is accessed via the Attributes gt Loading gt Thermal menu item This menu item is only displayed if a Thermal or Coupled user interface is chosen on the New Model dialog when creating a new model or when a Thermal or Coupled user interface is subsequently chosen on the Model Properties dialog Flux CL Q A Flux loading produces the LUSAS CL load type which in a field analysis applies a rate of internal heat generation Q Positive Q defines heat input Q A total flux a flux per unit length or a flux per unit area can be specified Q Flux is defined relative to the nodal coordinate system If the required loading directions of a global load do not lie in the global axes then a local coordinate may be assigned to the feature to transform the loads to local coordinate directions Distributed Flux FLD Q A Distributed Flux loading produces the LUSAS FLD load type which in a field analysis applies a rate of flux Internal Heat Generation CBF RIHG Defines the internal heat generation for an element Posit
547. te Patch load EXCLUDE ALL LOAD INCLUDE FULL LOAD BEYOND END OF LINE All Patch load components Patch load components in will be applied onto line as shaded area will NOT moved forces and moments as onto line shown 212 Chapter 6 Discrete loads over areas When discrete patch loads are assigned over an area the projection path s is are defined by the local x and y axes of the loading patch Each patch load component is moved along a specified local x or y direction and added to the first loading positions found inside the patch in that projected direction See the diagram that follows which illustrate the various options Options available when assigning onto areas are LJ Exclude All Load default LI Include Local X Projected Load LI Include Local Y Projected Load LI Include Local X and Y Projected Loads LI Include Non Projected Load Q Include Full Local X Load LJ Include Full Local Y Load LI Include Full Load Notes e Loads will not be moved to the edge of the search area if the entire patch load lies outside the search area e Loads inside the search area are not moved e Discrete patch loads assigned over areas are not work equivalent as the discrete points are simply lumped at the nearest node e Patch loads outside the search area are lumped onto the nearest edge of the search area 213 Modeller Reference Manual Patch Load Divisions Patch Load Local Coordinates Number of divisions in local
548. temperature is only applied to the node of the element specified e For step by step problems the initial temperature values need only be specified on the first load step e The Temperature load may be used to provide a temperature field for computing initial material properties in a nonlinear analysis To initialise the temperature field in a nonlinear field analysis the temperature loading must be applied using a manual loading increment 197 Modeller Reference Manual Case Study Temperature Gradient Through Slab Thickness Nodal and element temperature values accept gradient values for some element types This Top Surface 50 degrees C gradient applies a differential thermal load across the top and bottom surfaces of a Surface element The effect of this gradient is to cause bending in the structure See the Element Reference Manual for temperature LC Berry elements load input variations on an element basis Bottom Surface egrees In this example which assumes no slab eccentricity a 0 5m thick concrete slab is at 20 degrees Celcius The top surface is subjected to a temperature of 50 degrees Celsius and the bottom surface remains at 20 degrees Celsius To model this enter the following on the structural temperature loading dialog e The final slab mid surface temperature of 50 20 2 should be entered in the Final temperature field e The temperature gradient through the slab of dT dZ should be entered as 50
549. ter output in a readable form such as tabulated results contour or graph plots hard disk A data storage device usually fixed to a computer to act as the main data storage area Data is read from and written to the disk using a disk drive See a so disk drive floppy disk hollow volume A number of surfaces which are not perfectly merged together but are considered by Modeller to form a volume hardening The post yield behaviour of a material harmonic response The steady state response of a structure subject to one or more periodic or vibrating loads of constant frequency Also known as forced response See a so interactive modal dynamics heat fraction coefficient The fraction of plastic work which is available to be converted into heat energy This is used in temperature dependent and coupled analyses help Available on line by choosing Help topics from the Help menu or clicking on the Help push button on any dialog box See also context sensitive help dialog box 442 Index highway loads A subset of discrete point and patch loads usually in 2D used to apply loads to bridges or similar structures See discrete point and patch loads Hilber dynamics This is an accurate and efficient direct integration scheme which uses equations based on assumptions made by Hilber Hughes amp Taylor See also direct integration Hill criterion A yield criterion which caters for anisotropic plasticity See also Hoffman criterion
550. teration solver 295 Isometric 412 isotropic material 164 J Joint defining and assigning 137 local axes 139 material properties 140 Joint and interface elements 137 joint material models 187 Joint Models 187 JPG 375 K keyboard shortcuts 409 knife edge load 201 KS steel sections 153 L labels 74 119 Lamina thicknesses 244 Lanczos 296 lane load 201 large strains 179 layup methods 241 Layup defining a composite stack 243 visualisation 245 Lead Rubber Bearings 187 libraries 152 164 278 Licensing 13 314 lift off 190 Line by manifolding 78 line elements 145 line feature 69 76 linear 187 LMS CADA X Files 63 load combinations 324 load curves 254 321 load envelopes 324 Load train 201 loadcases creating 252 manipulating 253 viewing assignments 254 Loadcases creating 252 loading 194 local and global results 323 local coordinate 248 local sections 153 LT 14 lumped mass 140 Manifolding 91 manipulating attributes 116 manipulating geometric features 111 47 Index manipulating the view 37 mass lumping 140 master degrees of freedom 219 master slideline 235 material data editing 163 material libraries 164 278 material models 165 166 167 168 169 170 171 176 177 178 179 180 182 184 185 186 187 material properties 162 maximum value plots 343 maximum minimum load 324 menus 9 merging geometr
551. text menu key Memory shortcuts After features have been selected Ctrl M key Set selected items into Selection Memory Selection Modifiers for All Cursors Features displayed in the graphics window may be added to or removed from any initial selection using these selection modifers Shift key Add to current selection Ctrl key Toggle include exclude selection Ctrl Shift key Remove from current selection Tab key Cycle items at the same location Shift Tab key Cycle previous Alt key Intersect mode By default all items completely enclosed in a selected area will be selected By holding down the Alt key items intersecting the selection perimeter will also be selected The Alt key may be used with or independently from the Shift or Ctrl keys The Alt key can also be used with feature selection shortcuts e g Alt Shft L adds lines to the current selection Alt Return key Display properties of item 410 Appendix C Datatip Return key Adds current item to selection Browsing Selected Features Items in the current selection may be viewed in the Browse Selection window which can be displayed from the View gt Browse Selection menu item This window can also be triggered by aright mouse button click in the Selected area of the status bar at the bottom of the graphics area or by right clicking in a graphics window Selected features can be deselected and reselected as necessary from those listed
552. the output plot file results and then continues with the next increment Load step reductions can also be suppressed via the STEP REDUCTION section under the NONLINEAR CONTROL data chapter Using these procedures may help to locate the source of the problem when investigating an unconverged configuration in the LUSAS Modeller post processor e A pivot refers to the diagonal element of the upper triangular matrix that is formed after elimination has been completed Note that in the frontal solution these pivots are computed as soon as all the relevant equations have been assembled 405 Modeller Reference Manual e Computation of det K as part of a nonlinear solution scheme is not necessary since a count of the number of negative pivots NSCH in the log file together with the value of PIVMN gives all the information required e A zero pivot implies that det K 0 e If NSCH 2 then another unstable point has been reached and implies that det K gt 0 When An Eigenvalue Analysis Goes Wrong It is good practice to perform a linear static analysis prior to the eigenvalue analysis This eliminates the added complexities of the dynamic variables and will enable a check on the basic stiffness matrix for the structure Any warning or error messages in the LUSAS output file such as zero negative or small pivots should be investigated In the event of problems occurring after completing the linear static and the eigenvalue analysis consider some
553. the file from within the File Explorer When creating avi files it is recommended the Microsoft Video 1 compression method is used to reduce the file size Selecting this option will produce a good reduction in file size and perhaps more importantly should enable trouble free playback on the majority of PCs Using the Animation Builder Toolbar The animation tool builder tool bar can be found using the View gt Toolbars menu item Animation sequences may be edited or can be created frame by frame using the animation builder toolbar i Ho Ti al x KIA Printing Results Selected results values may be output to the screen in a tabular listing format for the active loadcase or for selected loadcases Once listed the results can be printed or saved to a spreadsheet The results for each loadcase are displayed on a separate tab in the print results window A model info tab appears in all output windows and provides basic information about the model To print results to the screen his use the Utilities gt Print Results Wizard menu item Q Active Loadcase outputs selected results from a single loadcase 370 Chapter 8 LI Load History outputs selected results for one or more loadcases Entity The Entity chosen dictates the type of results printed When smart combinations or envelopes are present the primary component can be set such that all other values are associated values which occur at the same time as the enveloped co
554. the slice if required The slice plane may be defined in any global or local plane which may be visualised prior to the slice operation A Surface of any shape may be used to slice a Volume by Subtracting the Surface from the Volume Separate unconnected cube and cylinder 2 volumes 97 Modeller Reference Manual pee Union of cube and cylinder Union of cube and cylinder Subtraction of cylinder Intersection simplify internal no simplify internal from cube of cube and geometry geometry 1 volume cylinder 1 volume 4 volumes 1 volume Geometry From Mesh An existing finite element mesh defined in a Solver results model file mys file can be converted into features such that each element is converted into a single feature Use of this facility will produce a similar model to that created by the use of the File gt Import menu item which permits the import of a Solver data file dat to create a model In using the Geometry from Mesh facilities lower order features are automatically created and the command describes the highest order of feature type that is to be created For example if a Line convert command is used on a single HX8 solid element mesh then 8 Points would be defined at the node positions and 12 Lines would be defined from the edges of the HX8 As a result be warned that very large models can be produced The currently selected elements are converted using the Geometry gt Point gt From Mesh Geometry g
555. the stress at which delamination is initiated This should be a good estimate of the actual delamination tensile strength but for many problems the precise value has little effect on the computed response If convergence difficulties arise it may be necessary to reduce the threshold values to obtain a solution Q Relative displacement The maximum relative displacement is used to define the stiffness of the interface before failure Provided it is sufficiently small to simulate an initially very stiff interface it will have little effect Coupling Model LI Coupled mixed interface damage Recommended method L Uncoupled reversible Unloading is reversible along the loading path LI Uncoupled origin Unloading is directly towards the origin ignoring the loading path Notes e Itis recommended that automatic nonlinear incrementation is used with the arc length procedure option set to root with the lowest residual norm when defining loadcase control e Itis recommended that fine integration is selected for the parent elements from the Solution tab of the Model Properties dialog e The nonlinear convergence criteria should be set to converge on the residual norm e Choose Continue solution if more than one negative pivot occurs from the Model properties Solution tab Nonlinear options dialog and set option 252 to suppress pivot warning messages from the solution process e The non symmetric solver is run automatically when mixed mo
556. ther a material has reached its ultimate elastic condition See also yield stress yield flags Indicate the spread of plasticity in a nonlinear material by plotting yielded Gauss points yield stress The level of stress at which a material is said to start unrecoverable or plastic behaviour See also Tresca stress von Mises stress 470 Index Young s modulus The linear relationship between stress and strain for a Hookean material zonal detection The area around each node on a slide surface that is used to search for contacting nodes on another surface zoom The action of increasing the display magnification of a specified portion of the graphics screen or structural model 471 Modeller Reference Manual 472 index A absolute envelope 324 acceleration loading 200 activation deactivation of elements 223 active composite lamina 248 active composite layer 321 active fibre 321 active load case 321 active loadcase 321 active mesh 119 Age 222 Akhras Dhatt optimiser 309 analysis 313 314 analysis control 279 280 animation 368 annotating the screen 40 frame coordinates 42 model coordinates 42 arbitrary sections calculation of properties 276 arc line 79 arc length control 284 Area Selection 410 assign 115 associativity 69 attributes 115 116 118 119 Australia steel sections 152 automatic equivalencing 221 473 Index axes 249 axisymmetric 307
557. thotropic material assumes that the material constants in the two or three principal directions may differ See also anisotropic 452 Index oscillation Repeated numerical variation often associated with out of balance forces residuals in a nonlinear analysis output file ASCII text file containing the results of a LUSAS analysis run It contains warning or error messages from the analysis It can optionally contain stress strain displacement and reaction results over damped system A system which has an equation of motion where the damping exceeds the critical value It has an exponentially decaying non oscillating impulse response page format The layout of a page in a print file may be controlled so as to include headers footers and titles parameter A variable that is given a value for use by a program or command Could also be known as a definable characteristic parasitic shear See shear locking parametric language Facility for using variables and a control structure as tools during program operation patch load See discrete point and patch loads patch test A test in which a convenient shape for example a rectangle has its interior divided into a non symmetrical pattern of the element to be tested The patch test then assumes a uniform strain over the rectangle and applying the relevant boundary displacements checks that the finite element solution delivers a constant stress everywhere peak val
558. tial energy need not necessarily coincide with the equilibrate state Typical values of slack and tight norms are 0 1 0 001 and 10 E6 10 E9 respectively LI Incremental Displacement Norm is the sum of the squares of all the iterative displacements as a percentage of the sum of the squares of the total displacements for the increment This norm is an incremental form of the total displacement norm previously described and the same comments regarding usage apply Nonlinear Output Control Nonlinear analyses may generate a vast amount of output In addition to the normal nodal and element output controls the frequency of nonlinear solution output may be restricted via the Output section in the Nonlinear Control properties The restart output facility enables failed or terminated analyses to be restarted from the last saved restart output dump This is particularly useful where the termination of the analysis was due to a failure of the solution process rather than that of the structure In this way the solution may be restarted from the last converged increment with a different or modified solution strategy For example a failed increment may be restarted under either constant load or arc length control Restarts are not supported by LUSAS Modeller and hence must be defined directly in a LUSAS Solver data file The Nonlinear Logfile During the course of a nonlinear analysis various information is output to the screen or logfile so that
559. tically trimmed at Surface boundaries Defaults Sets the defaults for symbols arrows and text which are used when visualising attributes Actual settings are controlled from the Attribute Visualisation layer for the current window The value and units for Gravity that are currently in use may be checked on this tab of the dialog The Advanced button enables a new Modeller option to be specified or particular default values or settings to be modified Advanced settings should generally only be modified with the assistance of LUSAS technical support Solver System Variables By default the LUSAS Solver is set up to operate efficiently for a wide range of modelling and analysis problems In some cases it may be occasionally necessary to adjust the Solver system variables Variables that can be modified inside Modeller are accessed via the File gt Model Properties gt Solver System Variables dialog Making changes to Solver system variables should be done only after seeking advice from LUSAS Technical Support 25 Modeller Reference Manual Using Windows Each view of the model is contained in a window View layers inside each window hold model information and can be added or removed from the current window as required Multiple windows can be opened using the Window gt New Window menu item Closing the last window will close the model Windows consist of the following components Q Drawing Layers l amp By default the first panel
560. tion thickness update A procedure used in plane stress situations where the thickness is updated due to the effect of Poisson s ratio thin element formulation An element formulation that ignores the effect of transverse shear deformation tied slideline A type of slideline setting that effectively ties two disconnected meshes together to move as if connected See also slides time domain The forcing function and the consequent response of a structure are defined in terms of time histories The Fourier transform of the time domain gives the corresponding quantity in the frequency domain See also frequency domain 466 Index time step The period over which the time is integrated in a dynamic analysis See also dynamic analysis toggle The act of turning on or off a function toggle button A button on a dialog which represents a parameter which may take only one of two values for example yes no total Lagrangian A strain formulation which has its reference as the initial configuration at the start of the analysis See also updated Lagrangian Eulerian geometric nonlinearity transformation dataset Describes a transformation in space for example a translation mirror etc which may be used to generate move or copy features See also move copy transformed freedom The transformation of the local axis system of a node from the global system transient analysis The field equivalent to a structural dynam
561. tion 87 e Updated Lagrangian A strain formulation that has its reference as the end of the last converged increment LUSAS Solver option 54 e Eulerian A strain formulation that has its reference as the current configuration LUSAS Solver option 167 e Co rotational Form of geometric nonlinearity in which large displacement effects are related to a set of axes that follow and rotate with the element LUSAS Solver option 229 Solution control Allows fine control over advanced nonlinear solution procedures 23 Modeller Reference Manual Continue solution after convergence fails This option continues with a nonlinear analysis even after an increment has failed to converge It is useful for creating a results dump of an unconverged results file to visualise problem areas This option should be used with care LUSAS Solver option 16 Continue solution if more than one negative pivot occurs will step over the LUSAS error that stops the analysis if more than one negative pivot is encountered This can be useful if pivot problems are encountered at an early stage but the problem is free from them during later stages This option should be used with care as it is likely to hide more fundamental analysis problems LUSAS Solver option 62 Non symmetric solution LUSAS Solver option 64 This is set automatically by LUSAS Modeller when for example carrying out a nonlinear concrete material modelling of cracking LI Coupling Opti
562. tion Through 3D slice a model and plot results on the section defined LJ Slice Resultants Beams Shells etc LI Graph Through 2D slice a model and plot a graph based upon the intersection of the elements sliced U Print Results Wizard printing of selected results to a grid or a file LI User Defined Results create results components from user defined expressions LI Vertical Axis sets the model X Y or Z direction to be the vertical axis LI Direction Definition sets the vertical longitudinal and transverse axes for a model to assist with model orientation and calculation of particular effects Q Library Management specify library locations and add and delete items from a library LI Section Property Calculation calculate cross sectional geometric properties for a range of sections LI Report Generation build reports containing model and results data and images from your model Some utilities for example Heat transfer are only listed if the appropriate user interface is in use Variations Variations allow parameters in attributes to be varied over the assigned geometry by defining the manner in which the parameter will vary If a variation is not specified the parameters within an attribute will be constant over the geometry to which the attribute is assigned Geometric section property variations along a beam are best defined using tapering or multiple varying section facilities The different types of variation a
563. tion of the longitudinal and vertical alignment and of the cross section shapes used is displayed on the dialog Longitudinal section visualisation only takes place once all required data has been entered and only for sections that are compatible The visualisation can be inspected by zooming and panning in the display panel A changing cursor image indicates whether the facility is enabled or not If necessary click in the panel to activate this facility Use the mouse wheel to zoom in and out Click and hold down the left mouse button or click and hold down the mouse wheel to pan Multiple varying sections would normally be defined to use the same section shape having the same set of fibre definitions throughout but differing sections can be accommodated In situations where the varying sections are too different to be connected together section visualisation on the dialog and fleshing of any assigned attributes on the model is not possible Incompatible section types Checking for incompatible section types is and can only be carried out when the OK button is clicked Multiple Varying Section Distance Types and Methods of Assignment A multiple varying section geometric line attribute can be defined for assignment to either Q A single line where section spacing distances are scaled to fit each line individually Q A series of lines where section spacing distances are defined for use with a pre defined reference path 157 Modeller
564. to the Surfaces and define and assign Supports and Load attributes so that the Surfaces are being forced towards each other 4 Define a normal tied mesh Constraint using the Attributes gt Constraint Equation gt Tied Mesh menu item Assign it to the Lines on either side of the gap One Line must be selected as a master and the opposing Surface as a slave If meshes on tied Lines have different spacing choose the Line containing the finer mesh as the master 5 Run Solver and view the deformed mesh The constraint equations will have prevented one surface from passing through the other 233 Modeller Reference Manual Crack tip attributes A crack tip attribute allows a crack tip location to be defined at a point in a surface model and at either a point or line in a volume model Crack tip attributes are defined from the Attributes gt Crack tip menu item and are only for use with 2D and 3D quadratic continuum elements After assignment the mid point nodes of elements adjacent to the crack tip assignment are automatically moved to the nearest quarter point position within the element and the continuum elements adjacent to the crack tip assignment are automatically replaced with an equivalent crack tip element When assigned to a point the crack tip always occurs at a corner node of an element When assigned to a line volume models only the crack tip occurs all along the line Assigned crack tip attributes can be visualised using symbols
565. to the stresses in the section not returning to zero at a free and unloaded end e Taking slices at a supported end of a structure can lead to discrepancies in the forces and moments when compared to a beam model due to the end effects taken into account by the full 3D shell modelling 360 Chapter 8 e Where a slice passes through a node in the structure results are presented for the contributions of the elements on both sides of the slice This is presented as results for the negative and positive local Z sides of the slice e Engineering thick beam elements are supported BMS3 and BTS3 along with thin beam BS3 BS4 BSL3 and BSL4 elements e Option 380 must be used for BTS3 elements when using eccentricitices offsets e When using 3 or 4 noded shell elements the mesh density should be sufficiently fine to capture the behaviour of the structure e When modelling curved structures it is recommend that regular quadrilateral elements wherever possible e Printing results for more than one loadcase will overwrite the text file named SliceResultantsBeamsShells prn each time Slideline Results Processing When a results file is read into Modeller from an lS S analysis that involves slidelines a group is created for E8 lug nonlinear md each slideline surface in the model These groups can R Pin be accessed from the Group Treeview Eye Slideline Resuli A context menu for each group name provides options on eel for making the m
566. tributes gt 2 5 Modeller Reference Manual Geometric gt Section Library menu item then select User Sections then select Local or Server before choosing the section required from the list available Arbitrary Section Property Calculator The arbitrary section property calculator is A Calcite accessed from the Utilities gt Section Property Dimensional data Calculated properties Calculator gt Arbitrary Section menu item It rein S T EE S A E computes the section properties area moments 4inedintne xY mine w poze of inertia and torsion constant of any open or nioena t wi closed section and calculates extreme fibre Comidne aeaea e by 01173553 positions for use when plotting stresses on Centoidye 0 555556 I Automaticmeshing Y 0 688362 fleshed beams The torsion constant is Mac oteinelt5 pS ea computed using the soap bubble analogy which tapezcidai beam As 268363 involves running a field analysis using LUSAS ee a T Haar process is carried out S ETE automatically Cross sections must be defined in the XY plane and can be created using points and lines but the cross section must ultimately only contain surfaces that define a single continuous shape Individual surfaces separated by gaps do not form a valid cross sectional shape for section property calculation purposes Voids or holes in a section must be defined as separate surfaces Any number of voids or holes can be included in a cross s
567. ts and a translation can be specified to locate the compound loading from away from an assigned point When created compound discrete loads are held in the Loading section of the Attributes Treeview in their own section named Compound Defining Discrete Point and Patch Loads Coordinates and magnitude LI For a point load each attribute defines multiple loads one concentrated load at each given vertex Q For patch loads the vertices combine to specify the shape of a line or patch load The load is specified at each vertex allowing the load intensity to be varied Patch load types include 8 node 4 node straight line and curve Projection Vector LI Projection Vector is used to work out which features are actually loaded The vector is followed in both directions and any features intersected by the assigned discrete load vertices projected in the direction of the projection vector are loaded in the direction specified by the untransformed load direction For patch loads defined by 4 or 8 vertices the projection vector is always perpendicular to the patch This example shows a typical 3D patch load where the patch is defined in space and projected onto the model 204 Chapter 6 LJ Untransformed Load Direction defines the direction of the loads in the patch before any transformation is carried out at the assignment stage Options are X Y Z or Surface normal Untransformed Load Global Z or Surface Normal Untra
568. ts results to be selectively plotted for the chosen group For details see plotting results for groups in the results viewing section Select Members Deselect Members atau Properties LI Change element type mesh only models permits changing the element type of a group of imported elements by description or by entering a specific known element name LJ Current Group Set the group to be the current group LJ Rename Enables a group to renamed LI Delete Deletes the group The group is deleted but the contents of the group are not LI Select Members Adds the members of the group to the current selection LI Deselect Members Removes the members of the group from the current selection LI Add to Group Adds the currently selected items to the group LJ Remove from Group Removes the currently selected items from the group LI Properties Displays a list of the member items of the group 34 Chapter 2 When the group defines a slice section the lS l2 otherwise generally available Rename Delete Add 24 Conerete_Dam md SEE Slices yl Slice 1 Slice 2 Visible to group and Remove from group options are unavailable but additional slice related options are include on the context menu chy Slice 3 visible Set as Only Visible Advanced Yisibility LJ Draw axes Draws the local axes for the Draw Axes slice section Note that options on the Delete Contours properties dialog allow for Select Members plotting of results
569. u e To print results and include model images in a report style format see Generating Reports Printing and Saving Pictures Views of the LUSAS model in the graphics area may be printed directly to the default printer S The File gt Print Preview menu item is useful for visualising the document prior to printing taking place Using the File gt Print menu item allows alternative printer settings to be used from the graphics area using the print button Note When a model is created the default paper size for printing use is now set from the settings of the default printer installed on the local PC This should help ensure that regional paper sizes are used in preference to otherwise specified sizes 374 Chapter 8 Saving pictures for use in LUSAS reports and other applications Views of the LUSAS model can be saved as BMP JPG or WMF files using the File gt Picture Save menu item BMP and JPEG files are saved to a fixed size of 1800 pixels in width with a height proportional to the size of the graphics window when the file was saved JPEG files are the most efficient to save in terms of file size Windows Meta Files now contain bitmaps instead of vectors for the modelling information with correspondingly smaller file sizes Text and annotation layer information held in a WMF file is vector based and is therefore scalable Note The contents of the graphics window can also be copied and subsequently pasted for use in other appli
570. uare mesh of pinned bars over the structure 24 Chapter 2 The length of the bars is considered to be the drape mesh size A smaller bar size provides a more accurate drape at the expense of computer time and memory usage Typically the drape mesh size should be about half the element size e Drape by mesh size Desired drape cell size If the desired drape cell size would generate more than the specified maximum number of drape cells then the drape mesh size would be adjusted to generate the maximum number of drape cells Likewise if the desired drape cell size would generate less than the specified minimum number of drape cells then the drape mesh size would be adjusted to generate the minimum number of drape cells e Drape by number Desired number of drape cells on draping surface This must be between the maximum and minimum values stated below e Drape by face multiplier A number that is used to multiply the actual number of mesh divisions on a draping surface to arrive at a desired drape cell number This must be between the maximum and minimum values stated below A default value of 4 is entered e Maximum number of drape cells Maximum number of drape cells to be generated e Minimum number of drape cells Minimum number of drape cells to be generated e Extend drape grid one row Ensures the edges of the component are fully enclosed by the draping grid Note that the grids for LUSAS draped solids and shells are automa
571. ue plot A post processing plot that shows the largest maximum or minimum or both values of a results entity on the screen The peak values can be shown as a symbol or as a value penalty function method A method of monitoring the interaction of two contact surfaces which upon contact imposes interaction forces to oppose penetration 453 Modeller Reference Manual penetration A term used in a contact analysis to define the relative overlap of meshes on separate contact surfaces Also known as interpenetration perfectly plastic A material that will not sustain additional load after yielding The stress strain curve is effectively flat above the yield stress peripheral An external input output printing or storage device perspective view Takes into account the distance from the viewpoint to the object when displaying the plot phase angle The ratio of the in phase component of a signal to its out of phase component gives the tangent of the phase angle of the signal phase change The transformation of a material between phase usually being accompanied by a liberation or absorption of heat picking See cursor selection picture files Used to store LUSAS pictures in a neutral plotting format pivot A pivotal term in a matrix that is being solved using Gaussian elimination See also small pivot negative pivot diagonal decay planar Lying in a flat plane See non planar plastic hinge The formation
572. ues are computed to some degree of accuracy The convergence criteria for the inverse iteration scheme is therefore based upon the mass orthogonality tolerance i jzjPi MDj lt Eis for all eigenvectors i and global mass matrix M Lanczos When convergence is achieved the Lanczos eigenvalue solver is usually faster than the subspace or inverse iteration solvers and can use significantly less physical memory and hard disk than subspace methods For these reasons it is ideal for large numbers of requested eigenvalues and for large problems although convergence cannot be guaranteed The maximum number of Lanczos steps to be taken is set to 100 by default but can be altered and should always be greater than the number of modes requested Fast Lanczos The Fast Lanczos solver is both faster and much more robust than the original Lanczos solver and is the recommended solver of choice for all eigenvalue analyses Centripetal Stiffening Effects In rotating machinery load correction terms that arise from the effects of rotation may significantly influence the natural frequencies of vibration Within LUSAS the load correction terms due to centripetal acceleration can be considered The load correction terms due to Coriolis forces and angular acceleration are currently ignored because they result in non symmetric damping and stiffness matrices respectively Notes e The relationship between the eigenvalue A and the angular frequency
573. ults value and node location can be annotated LI The appearance of the contour key can be adjusted to specify the number of significant figures draw an outline around each colour in the key and draw red or blue uppermost 346 Vectors Chapter 8 Loadecase 1 Tithe Dead load Results File 0 Entity Stress Component Wis 156 618 117 453 78 309 39 1545 0 0142109E 12 39 1545 78 309 117 463 156 5618 Mas 195 326 at Hode 19 mlin 157 065 at Hode 24 Setting the Contour Levels By default the levels at which contours are plotted are calculated automatically but they can also be set explicitly A contour level corresponds to the boundary between adjacent colour fringes or the line of equal value Q Setting the range automatically can be done by specifying either the number of contours or the interval value between contours Q Automatic contours levels can be set to pass through a certain value The maximum and minimum contours may also be specified Q A global range can be used to fix the contour levels between different contour displays This is often used before animating contours so that all animation frames use the same contour range It is also useful to fix the contour levels manually when comparing results from different loadcases or when using multiple windows Tip Contours use the colour map to define the colours used It is often useful to adjust the colour map so that low stress contours are set to whit
574. undary conditions Loading constraints and supports applied to a finite element model Boundary conditions are sometimes termed nonlinear where the model changes in contact such as with a lift off support or a contact analysis See also constraint equation supports bracketing The accurate computation of a critical point which may be either a limit point or a bifurcation point branching The tracing of an alternative solution path from a bifurcation point buckling See eigenvalue buckling buffer A temporary area in which data is stored Cartesian axis set A standard set of axes based on the global XYZ axis set but not necessarily in the same position or orientation See also local coordinate system cylindrical axis set cascade The action of bringing down a secondary menu by selecting an entry on an upper menu level Usually designated by a right facing arrow central processor CPU The heart of the computer system The CPU interprets and executes programs routes information controls input and output and temporarily stores data 425 Modeller Reference Manual checking See data check checklist A list of items through which to work to establish the integrity of a model or its results classical yield Plasticity formulation where yielding is independent of the sign tension compression of the stress causing it e g von Mises Hill close contact detection A facility that automatically inserts
575. ural geometry during loading for example snap through of a hemispherical cap geometric properties Define the geometrical information about the feature to which they are assigned which has not been specified for example the thickness of a shell global A term indicating that an entity is expressed relative to the global Cartesian axis set See also local gradient See temperature gradient granular A characteristic of compound materials such as soils and rocks graph dataset A dataset describing the x axis and y axis data required to construct and display a graph graphics area See graphics screen graphics screen The LUSAS main window consists of the areas used to control the software and a central graphics area which displays graphical information 441 Modeller Reference Manual group A collection of features given a reference name and used for manipulation of the model Guyan reduction A finite element approximation to low frequency natural vibrations may be obtained by considering only those freedoms known as master freedoms whose contribution is of most significance to the oscillatory structural behaviour The effective selection of master freedoms is central to the accuracy of the simulated structural response grillage A finite element mesh made up of interlocking gril elements See also beam element HA HB loading See discrete point and patch loads hard copy A printed copy of compu
576. ure Defines the spatial geometry of the structure Uses an associative hierarchy See also associativity 437 Modeller Reference Manual feature loads Loads that are applied to a pre processing feature They can be varied using variation functions fibre location s The position s defined on a beam cross section that can be used to calculate beam stress results for plotting force and moment diagrams field analysis Corresponds to the solution of the general quasi harmonic equation A wide variety of problem types are possible including thermal seepage incompressible flow and elastic torsion field elements Finite elements used in a field analysis See also field analysis file privilege The settings that can be given to a file or directory to control who on a system has access to read from write to or execute the file file protection The devices or procedures that prevent unintentional access or erasure of computer files or directories file selector External files are chosen using a file selector box which is machine dependent Generally the filename can be entered in an edit box or chosen with the cursor from a presented list See a so dialog box fine integration A method of element integration using an alternate selection of a larger number of Gauss points Can sometimes have the effect of stiffening the mesh See a so coarse integration finite element A sub region of the overall model for which t
577. ures 111 Damage 177 damping 223 DAT 66 67 data file 50 deactivate elements 223 deassigning attributes 119 default assignment 151 default attribute assignment 116 defining surface 151 definition for Surface 151 deformed mesh 344 delamination model 141 185 deleting geometric features 69 design factors 333 Diagonal Decay 400 diagonal solver 309 diagrams 349 dimetric 412 Direction Definition 273 discrete loads 201 editing 207 discretisation 120 displacement loading 200 distance type multiple varying sections 154 Distributed Flux 217 distributed load 196 distributed mass 140 drained undrained soil 179 draping 243 Draping grid extending 247 visualisation 247 drawing attribute labels 119 Drucker Prager material model 171 DXF 60 dynamic analysis 300 302 eccentricity 150 Eccentricity 151 edge collapsing 128 eigenvalue analysis 292 299 406 elasto plastic material 164 167 168 169 171 176 ELDS loading 199 emulating behaviour 14 end releases for beam elements 123 envelopes 324 environmental load 218 ENVT TDET loading 218 equivalencing 220 errors 399 EU steel sections 153 excel 386 Export files 59 Expressions supported 419 facet 71 fatigue analysis 331 feature based models 16 475 Index Feature Selection 409 feature based models 16 FiberSIM defining composite stack 242 Fibre directions visuali
578. ures modelled using plate Nodal Line gt membrane or shell elements require a Thickness to be defined for each surface Local Surface Element Axes Eccentricity e ve Eccentricity ___ Plate Shell Centre Line Bending Plane Q Optionally an Eccentricity can be specified for certain element types Eccentricity is measured from the bending plane to the nodal line in the local element z direction Geometric Joint Properties Geometric attributes are defined for joints using the Attributes gt Geometric gt Joint menu item For certain joint elements eccentricity in the local z direction is an optional geometric property that can be defined See the Solver Reference Manual for details Setting Geometric Attributes for Default Use A geometric attribute may be designated as the default assignment using Set Default on the context menu When done default attributes are automatically assigned to new geometry as it is defined Visualising Geometric Properties Fleshing Beams of standard or arbitrary cross section that are held in section libraries surface thicknesses and offsets can be visualised on the geometry model using the fleshing button or from the Attributes Layer f properties Geometric tab From the geometric settings dialog or from the context menu of the fleshing button the cross section may be exaggerated 151 Modeller Reference Manual in size and shrunk in from the ends of the assigned Line t
579. ures or decimal places for this chapter as presented in the report Note It is possible to visit this dialog several times to create multiple chapters each of which can have different ordering scope and loadcase choices For example you can create one chapter describing the lines in group 1 and subsequently to create a different chapter 377 Modeller Reference Manual describing the lines in group 2 Once created the order of chapters in the report can be modified at any time by dragging and dropping them up and down the Report Treeview Add or Edit a Results Subchapter for an Entity You can create or modify a section within a results chapter Select the Add button on the Chapters dialog to display this dialog LI The Entity chosen dictates the type of Result Subchapter x results The component chosen is only appropriate to Envelopes and Smart Entity EENE Combinations and controls the primary Transformed Mone component equivalent to the component chosen when the Envelope or Wood Aren Hone Combination is set active LI The Transformed and Wood Armer a N settings behave as on other dialogs Specie empre LI Use the All Components or Specify components and buttons to control Location Averaged nodal which results component values will be W Summan D Nodal coordinates added to the report M Tabular results eae Significant figures f LI The Location drop down specifies e seee
580. urface filter only Surfaces can be ho Select Points selected he Select Lines LI Selection filters can be activated either from the drop ko Seet ure buttons to the right of the cursor button or using Select Val keyboard shortcuts To display the drop buttons click on Ro Select volumes the down arrow to the right of the cursor button Rn Select Mesh Alternatively hold down the appropriate key whilst RK Select Nodes selecting using the normal cursor as follows he Select Elements Rea Select Annotation G Geometry selection filter P Point selection filter L Line selection filter 29 Modeller Reference Manual S Surface selection filter V Volume selection filter M Mesh selection filter A Annotation selection filter N Node selection filter E Element selection filter A Annotation selection filter When a specific selection option has been chosen the on screen cursor will show a graphical representation of the chosen option Mesh only models hk ly The selection cursor will select only Nodes Elements ix Select Any or Annotation MS Select Mesh l i o Select Nodes selected 1 e with the Edges filter only edges of 4 elements can be selected and with the Faces filter only s Select Edges Faces can be selected k Select Faces Selection filters can be activated either from the drop Reo Select Elements buttons to the right of the cursor button or using keyboard shortcuts To displa
581. used Line Function Variations A Line function variation defines a variation by a series of functions specified at distances along a Line The function is specified in terms of the parametric or actual coordinate along the Line The interpolated value of the variation at any position along the Line is calculated by finding the interval in which the position occurs and then substituting the parametric or local distance into the function Line function variations are defined from the Utilities gt Variations gt Line menu item and selecting Type Function LI By Equal Distances in u defines F 1 0 2 u i F 0 F 1 0 2 u F 0 functions in terms of u the parametric distance along the Line In this example the Line is split into a specified number of distances each with an associated function F 2 LI By Unequal Distances in u defines end _ a series of parametric or actual i distances and a set of functions The distance specified is the starting position for the function associated with it Each distance must have an associated function specified To enter a maximum cut off position associate a zero function with it In this example a parametric distance of 0 is associated with the value 0 0 a parametric distance of 0 33 is associated with u 2 and a parametric distance of 0 92 is associated with the value 2 0 Surface Variations On Surfaces interpolation may be defined using a grid of values or a set of line
582. user can change these inputs that may be either loading parameters such as width length and intensity etc or even the type of vehicle at any time For each modification the name of the attribute and the equivalent discrete load values are modified Although the name of the attribute is altered the attribute itself is merely modified and so the assignment links between the bridge structure and the load will not be lost e Selecting the Edit Attribute menu entry displays the equivalent discrete loads These values may be changed but this breaks the link to the original definition dialog and a warning message will be displayed Editing of automatically generated discrete loading data such as that created by the use of the prestress wizards is not permitted Editing patch load divisions e When the first discrete load type is added to the Attributes Treeview a Patch divisions object is also created Double clicking on this object displays a dialog which allows the type and default number of patch divisions used on discrete patch loading to be edited 207 Modeller Reference Manual Case Study Hydrostatic Loading In this example a discrete patch load will be used to apply a hydrostatic load to the side wall of an underground box culvert 1 o The box culvert wall is defined using a Surface in the global XZ plane with corners at coordinates 0 0 0 5 0 0 5 0 3 and 0 0 3 Define a Surface using the New Surface button at the
583. user content items appear as separate chapters in the report Each report template can include any number of chapters that define the model attributes and analysis results to be viewed Note that the creation of results chapters is only possible when results are loaded on top of a model Any number of reports templates may be created and saved in the Reports Treeview of a model The order of information in a report can be changed by dragging and dropping the chapter names up and down the Report Treeview Reports are viewed in a third party industry standard report viewer called BusinessObjects Crystal Reports included with your LUSAS software Report data may be exported to Microsoft Excel spreadsheets for additional calculations to be carried out as well as being exported in PDF RTF for use in Microsoft Word HTML and other formats 375 Modeller Reference Manual If it is desired that only results values are to be viewed on screen or be selectively printed or output to spreadsheets the Print Results Wizard can be used RIA E is 2d a flow mak E Preview frame masis 2 Tues day September 29 2009 Date saved 29 Sep 09 10 42 20 Title frame analysis Model Units Nm kg s C Report Units Nm kg s C Model Tiile Simple 2D Frame Model File frame malysis 2 Creating a Report A new empty report template is created by selecting the Utilties gt Report menu item or from right clicking New Report from the
584. using the File gt Import menu item Phase I data geometric entities is read from the PATRAN neutral file Phase II data is ignored The following table shows the supported Neutral file packet types for import into LUSAS Packet Title LUSAS Equivalent 25 Title Used for information purposes only 26 Time Date Version Used for information purposes only 31 grid Point 32 line Spline Line defined by 2 Points 33 patch Bicubic Surface defined by 4 spline Lines 34 hyperpatch Volume 47 trimmed surface Bicubic Surface and spline Lines defining the trimmed regions Tip Imported PATRAN data is particularly suited to tidying since all defined geometry is spline data See Tidying Imported Lines and Surfaces for more details PATRAN Export Export of LUSAS data to PATRAN was last supported in LUSAS V14 3 Solver DAT Import Solver DAT files are created by LUSAS Modeller during the tabulation phase They contain the data required by LUSAS Solver to perform an analysis Both Geometry and Mesh data from Solver DAT files may be imported into Modeller Point Line Surface and Volume geometry data from Solver DAT files can be imported using the File gt Import menu item When a file is selected the Advanced button can be used to specify import parameters STEP Import Export STandard for the Exchange of Product data STEP files are imported according to Part 42 of the Geometric and Topological Representation by using the File gt Im
585. ust include a factor of 2p for n 0 v w 0 n 0 u the implicit integration around the surface For harmonics n 1 u 0 w 0 other than n 0 the factor should be p Certain restrictions are n gt 1 u V n 1 v 0 applied to the freedoms of nodes lying on the axis of w 0 ka U V symmetry These conditions in the table shown are automatically imposed on the centre line nodes Dynamic Eigenvalue And Harmonic Response Analyses A Fourier analysis processes each harmonic individually as they possess their own unique stiffness mass and damping matrices and load vector By selecting just one harmonic a dynamic eigenvalue or harmonic response analysis can be executed for that particular harmonic The complete structural response can be obtained by superimposing the different results from the selected harmonics The Fourier control should specify just one harmonic of a series The automatic calculation of the load coefficients from a given load input is suspended and you must input the appropriate load coefficient if this is not known it may be obtained from a static analysis Note that to 307 Modeller Reference Manual represent a global load the applied load will have components in both the tangential and the radial directions see the Theory Manual for details of the loading calculations Only one loadcase may be processed Inertial Loading The operation of the inertial loading input using the load type body force is slightly different to th
586. ut significantly faster although convergence is not guaranteed As well as calculating an eigenvalue range as with the inverse iteration method it is also able to calculate the minimal and maximal eigenvalues 292 Chapter 7 Having calculated all the required eigenpairs the solution is completed by calculating error estimates on the precision with which the eigenvalues and eigenvectors have been evaluated and normalising the eigenvectors according to a user specified criterion For further details regarding the operation of the eigenvalue extraction facility refer to the Theory Manual Subspace Iteration The first step in the subspace iteration procedure is to establish the number of starting iteration vectors This should be greater than the number of required eigenvalues to increase the rate of convergence It is important to remember that the number of starting iteration vectors cannot exceed the number of degrees of freedom of the system Experience suggests that the number of starting vectors should be determined from the expression nive min Z2 nroot nrootts nvbz where nivc is the number of starting iteration vectors nroot is the required number of eigenvalues nvbz the number of degrees of freedom in the structure Occasionally insufficient eigensolutions are computed in the initial eigenvalue analysis The number of eigensolutions can be increased by using a restart and re specifying the Eigenvalue control T
587. ut menu item may be used to hide or show the Text Window The Text Window context menu allows the Font to be defined and the output to be directed to a log file By default the selection mode is set to select lines of text This may be changed to select characters by changing to Character select mode but subsequent output to the text output window will be slower Usually when an error message or warning relating to a particular object is written to the text output window extra information is available by double clicking on that line of text In doing SO a popup window provides options to help identify the offending area of the model For example if a Modeller error refers to an assignment on line 25 it may be selected moved to the centre of the screen scaled to fill the screen have its properties displayed or be identified by an annotation arrow or a temporary indicator Similarly if a Solver error or warning refers to a particular numbered element the popup window will help you find that element quickly and easily Toolbars Toolbars contain the toolbar buttons On initial start up the Main Define and View Toolbars are displayed All toolbars can be shown hidden or customised using the View gt Toolbar menu item When a modelling session is completed the current toolbar settings are saved and reloaded the next time Modeller is used User defined toolbars and buttons can also be added to the user interface Actions are assigned to user d
588. utilities paths are not directly assignable to geometry and can only be edited by editing their properties via their context menu 267 Modeller Reference Manual Uses Reference paths are primarily used for line beam models such as those that are required for staged construction analysis and for use with grid or grillage models where longitudinal and transverse beams are modelled with individual grillage or line beam elements Defining paths Paths are created by using the Utilities gt Reference Path menu item In its simplest form a reference path can be defined as a line between two points quite separate from the model data if a straight path is to be considered or be created from the model geometry itself and contain as many defining points as the lines from which it has been created If the latter is done it is important to remember that the model geometry has been used to arrive at the points required to generate a reference path but no connection between the model geometry and reference path data exists Reference paths are usually defined to be along and coincident with beam lines For clarity it is also possible to define reference paths away from beam lines but if the beam lines are not straight perhaps they curve on plan the path should be defined above the beam lines rather than be defined in the same horizontal plane Reference paths can be defined by e Specifying the coordinates of each defining point e Importing ge
589. variations applied to the boundary Lines For interpolation by grid the interpolation order may be constant linear quadratic or cubic Q Surface By Grid defines a grid of values in Surface local x and y directions Surface grid interpolation can only be used on 3 and 4 sided Surfaces 265 Modeller Reference Manual Quadratic vs Constant Surface variation The quadratic variation in the local x direction is specified with three interpolation points The constant variation in the local y direction requires ee no additional points A total of three TE EEE z oca uadratic values are required 2 Divisions 3 Points Cubic vs Linear Surface grid variation The local x direction takes a cubic variation defined with four interpolation points and the local y direction takes a linear variation using three interpolation points A total of twelve values are required Local Y Linear 2 Divisions 3 Points 4 Local X Cubic 3 Divisions 4 Points LI Surface By Boundary defines values by specifying variations around the Surface boundary Lines A variation must be specified for each Line in the Surface definition If no variation is required along a Line a constant order variation must be specified Care must be taken to ensure that values at common points are common to both variations meeting at that point otherwise an error will occur Variations are defined in the same directio
590. ve menu item A black dot is shown next to a local coordinate attribute to indicate it is active By default the active coordinate is visualised on the graphics area this can be switched off from the Window properties Click on the View Axes tab to change the view axes settings Local coordinates assigned to features may be visualised in the same way as all attributes 251 Modeller Reference Manual Loadcases Loadcase dependent assignments analysis control load IB 1 amp Q Z 16 H 4 frame_2d mdl combinations envelopes and loadcase results are displayed Loadcases 2 ey H 4 Structural in the Loadcase Treeview gt The active loadcase controls H N 1 Loadcase 1 Supports which loadcase dependent attributes are visualised in the 2Fuly Fixed A H 4 Loading graphics window and which results are displayed A 1 Self Weight a A Fle 2 Load 2 loadcase is set active using its context menu At least one 3 Loading s 2 Sway Load loadcase will always exist in the Treeview Combination i Ry Combination and envelope options Load curves For analyses in which the load varies with time or increment number load curves may be used When using load curves all loads must be assigned to a load curve instead of a loadcase All other loadcase dependent attributes support slidelines etc and analysis control is assigned to loadcases in the usual way The analysis control assigned to each
591. ve their fibre definitions defined manually in order for stress results plots to be created for fleshed beams The use of the arbitrary section property calculator is described further in the worked example Arbitrary Section Property Calculation and Use See LUSAS Examples Manual Precast Beam Section Generator The Precast Beam Section Generator is available for Bridge and Civil amp Structural software products only See Application Manual Bridge Civil amp Structural for details 2 1 Modeller Reference Manual Box Section Property Calculator The Box Section Property Calculator is available for Bridge and Civil amp Structural software products only See Application Manual Bridge Civil amp Structural for details Library Management Libraries are used to store standard section and materials properties The location of the section and material libraries may be defined from the Utilities gt Library Management gt Library Locations menu item The local section library is always located in the current working project directory while the server library may be located anywhere on the computer network Add Section to Library Basic geometric section properties may be manually added to either the local or server section library from the Utilities gt Library Management gt Add Section menu item This facility is intended primarily for entering section data of an unspecified cross sectional shape Section property calculators ex
592. velope Smart Combination results tab not shown is only added to the dialog if a model contains envelope or smart combination results e Use the Add button to add entities for inclusion in the report as results sub chapters When added results sub chapters are shown in a grid form at the top of the dialog By selecting the Entity name in the grid you can subsequently Edit or Delete existing content e Use Order by to dictate the order in which the tabular results sub headers are presented This is similar to the concept of sorting data by column header in a spreadsheet program The order by options are Loadcase Features Features Loadcase and Loadcase Mesh The use of the Order by facility is of particular importance when exporting results to a spreadsheet format where the use of Order by Loadcase Mesh is recommended because of the reduced number of blank lines it creates in the output file e Use the Loadcases button to display a dialog which restricts the chapter to display results for All Active or Specified loadcases or combinations By default all loadcases are selected e Use the Report on button to display a dialog which controls the scope of the chapter to be created for example to restrict the chapter to display results for the Full model the Visible model or a Specified group only By default the whole model is selected e Chapter name can be edited if the default or previously entered name is to be altered 37
593. visualisation Points Lines Combined Lines Surfaces and Volumes can all be independently not shown as required Note Not showing a geometry type is not the same as making all items of that type invisible as the presence of that geometry will affect the visibility of lower order features 1 e A Line can not be made invisible if a Surface using that line is not shown visible but not drawn because the drawing of Surfaces has been suppressed in the Geometry layer properties Display Style Geometry can be displayed in a number of styles By default Geometry is viewed in wireframe mode with hidden parts shown but a wide variety of styles can be obtained by mixing the options for wireframe with and without hidden line and solid plots Some examples follow Default wireframe geometry visualisation Wireframe with hidden Parts removed 70 Chapter 4 Wireframe with hidden parts draw dashed Solid fill with wireframe and hidden parts removed Solid fill with wireframe hidden parts removed and Points hidden Facet Density By default lines and surfaces are assigned a facet density which is used in visualisation Facet density effectively controls how smooth a line or surface will look when drawn to the screen Straight lines arcs and splines are all drawn using facets of a particular line length Surfaces are drawn using facets that are triangular The default facet density may be changed prior to geometry definition from the Geometry
594. visualised at top of section 159 Modeller Reference Manual Line mesh density Note that when modelling varying cross sections with constant section beam elements care should be taken to ensure that sufficient elements have been assigned Greater than 8 elements should be used for small variations in cross section along the length of the geometry to which the section has been assigned and considerably more elements should be used for larger variations Using specified distances from a start of a path Specified distances from a start of a path are used when it is desired to define a whole series of similar sections for either a complete structure or for a particular length of a structure and assign them all to a series of lines on a model with reference to a path This most powerful of methods can produce models very quickly As an example if a model is defined local to an origin of 0 0 0 the reference path origin can be defined to start at say 100 and then by entering distances of 106 112 and 127 with reference to a path assignment sections would be positioned at those distances along the lines selected Greater than constant section beam elementsto be used along the length of the geometry to whihthe section has been assigned for small variatie in cross section so a minimum of 2 elements per ine are required in this case Value of distance at stat of path stated Reference path Single geometric line attribute
595. which the Lines were with selected i e first Line in selection memory joins to first Line in selection Add SMSEK etc to memory X In the example shown Surfaces 1 and 2 are defined by first selecting Lines 1 and 2 then adding them to selection memory then selecting Lines 3 and 4 and using the Surface by joining command Intersection LI By Intersection Defines a Surface at the intersection of two selected Volumes Manifolding Manifolding is the process of creating geometry which lies on the surface map of an existing Surface LI By Manifolding Existing Surfaces may be projected or laid onto an existing Surface A Surface to be projected onto is placed into Selection Memory and the Surface to be projected is then selected prior to choosing the Geometry gt Surface gt By Manifolding menu item The new Surface is created normal to the selected item in selection memory and will lie on the map of the underlying Surface LI Manifold by Lines Defines a Surface positioned on an existing underlying Surface with its boundary specified by edges or vertices In this example a Surface is created by Joining any 5 combination of the Points and Lines shown Any new Lines created will automatically be manifolded onto the underlying Surface er 91 Modeller Reference Manual Extrusion LU By Extrusion Defines Surface by extruding selected Lines a specified SSS distance The positive direction may be defined by an additional Poin
596. window frame frame coordinates Q Visibility The annotation can be made visible on all windows or just the current one Q Pen The pen used to draw lines or polygons can be selected from the pen library Line thicknesses can be edited The font used for text annotation can be modified by clicking on the Font button Q Name The identifying name of the annotation item If no name is entered an automatic numeric identifier is allocated Notes e By default the anchor point of all annotation is positioned in frame coordinates from the bottom left corner of the page This enables the annotation to be positioned separately from the model If negative values are specified for the anchor coordinates then the annotation is positioned from the top right corner of the page e Annotation may be tied to the model by specifying the anchor point in model coordinates e Annotation positioned in frame coordinates can be moved by selecting the annotation in the graphics window and dragging to the required location e Annotation lines are used where 2D graphing results are to be recreated at defined locations See Results on Sections Through a Model e Polygons are used when a section through a 3D model is to be recreated at a defined location See Results on Sections Through A Model Saving a Model When a model is saved using the File gt Save menu item all model properties views and associated values are saved also If a results file was open when th
597. with a black dot next to the fibre name amen Felg Bg 270706 EA major y roof member m F sE Surface 1 S 1 Unit Thickness ES Material 1 e Right clicking on a fibre name in the ob a AT Pi Treeview and choosing Set Fibre Active will display results for just that fibre e Right clicking on a fibre name in the b Treeview and choosing Set Fibre Name will display results on all members with that fibre name Notes e Standard sections extracted from the section library include extreme fibre locations for all sections e The standard section property calculator automatically includes extreme fibre locations for all cross sections that it supports e Models created prior to version 14 2 will not have any fibre locations data stored for each beam However the relevant fibre location data can be added automatically by double clicking on each Geometric line entry in the ob Treeview and re selecting the same section size from the appropriate sections library e User defined beam cross sections require fibre locations to be defined manually in order for stresses to be displayed on the diagrams and values layers Beam Stress Resultants From Beams and Shells The slice resultants from beams and shells facility allows the computation of the equivalent beam stress resultants for flat or curved thin and thick shell models This allows the conversion of the results of a complex shell model into an equivalent beam analogy for use in design codes o
598. would cause buckling e g a strut subjected to tensile load instead of compression 407 Modeller Reference Manual U Alternative Buckling QSL8 elements have given negative eigenvalues for thin structures and resulted in negative projected mass errors The remedy is to use the alternative buckling algorithm where positive eigenvalues should be obtained This is always the case except when the buckling load factor is less than unity Adjust the load level to ensure that all the load factors are greater than 1 if this occurs Additionally use Option 18 fine integration rule for the element to overcome the excitation of any element mechanisms Why Loading is Ignored in an Eigenvalue Analysis In a standard eigenvalue analysis the loading will be ignored completely For a linear analysis once the eigen pairs have been obtained the stress distribution s for each mode shape F is evaluated using s D B F where D and B are the elastic constitutive and strain displacement matrices respectively The reason that the forces have no effect on the vibrational behaviour is because the loading conditions in a linear analysis do not affect the D or B matrices To include their effects a nonlinear D and B matrix must be evaluated prior to the eigen analysis This is achieved by performing a static nonlinear analysis with a geometrically nonlinear option followed by an eigenvalue analysis In this way the effects of the loads are included via the updat
599. xisymmetric structure with non axisymmetric loading Achieved by representing the circumferential variations of applied loads and structural displacements as the sum of harmonics of a Fourier series fracture Any form of failure in which stress release occurs See also ductile fracture frame diagram This is a graphical representation of the forces and moments in bar and beam structures 439 Modeller Reference Manual frequency domain When the forcing function and response of a structure are defined in terms of their frequency content The inverse Fourier transform of the frequency domain gives the corresponding quantity in the time domain See also time domain freedom See degrees of freedom FRF Denotes a frequency response function This expresses the transfer function used in modal dynamics calculations to transfer from the global to the modal domain and allows frequency and time domain response calculations to be carried out from the results of an eigenvalue analysis friction angle Material property of granular properties such as cohesive soils and rocks frontal method A method of solving simultaneous equations based on Gaussian elimination frontal optimiser The part of the code that controls optimisation The order in which the elements are presented for solution makes a significant difference in the time taken and the space required for the solution The frontal optimiser attempts to order the elements in
600. y New Ctrl key O key Open Ctrl key S key Save Ctrl key P key Print Ctrl key A key Select all items Ctrl key C key Copy Ctrl key X key Cut for text only Ctrl key V key Paste Ctrl key Z key Undo F2 key Rename when name is selected F5 key Redraw 413 Modeller Reference Manual 414 Appendix D Appendix D Tip of the Day Tip of the Day When starting LUSAS Modeller useful tips can be optionally displayed This is done by selecting the Help gt Tip of the Day menu item and ensuring that Show tips at Startup is selected Next and Previous tips can be browsed The following is the list of tips supplied in the current release version e If you haven t already done so please read the Getting Started leaflet e The Keyboard Shortcut Guide will help you use LUSAS in an efficient manner e If you lose unsaved edits because of a power hardware or software failure restart LUSAS open the model again and chose yes when prompted to recover e Saving your work frequently prevents data loss and makes undo redo work faster e Help is available even for greyed out buttons and menus First click on the Help button on the main toolbar then click on any menu item or toolbar button e Right clicking in a window displays a context menu relevant to both that window and any selection within it e Toolbar buttons with a small triangle to the right hand side are menu buttons Press the left hand
601. y creating arithmetic expressions based upon LUSAS results entities components model data and other user defined results component calculations A component name and description can also be entered A results file must be loaded in order to define a user results expression 342 Chapter 8 e Clicking on the drop list button in the Entity cell lists all entities available for the particular results file loaded e Clicking on the launch dialog button in the Expression cell displays a dialog populated with valid variables for the selection made in the Entity field By use of these variables and usual arithmetic syntax a user defined results expression can be built and assigned a name and a description For details of expressions and functions supported see Input and Output of Real Numbers in LUSAS in Appendix E E User Defined Results x bw prphiT 2 4 s As Aree of tension reintorcemert mm math 15 Siran Thick Plate Stran Thick Piste h cnom phiS phiT 2 d Ettechve depth mm Strain Thick Piste aphaCC tchiganmac tod Design cylinder strength of concrete for bending MPa Strain Thick Piste tykiganenasS fyd Design yield strength of tension reinforcement MPs rat EN 1992 1 1 Fig 3 6 Strain Thick Plate fywkigaeamaS tywa Design yield strength of shear reiniorcemert Pa Strain Thick Plate iFitck lt 50_0 5 0 6 fek S0 400 lamda Praportion of compression zone used in design ret EN1992 1 1 3 1 7 Siran Thick Pl
602. y geometry is assumed to remain constant The displacements of the same body subjected to various forces is described by equations of static or dynamic equilibrium the temperature distribution is assumed not to vary with displacement To include the effect of the change in geometry in the thermal analysis and the change of temperature in the static analysis requires that this information is separately calculated by the appropriate analysis and then transferred This process is known as thermo mechanical coupling Thermo mechanical coupling may be sub divided into two classes depending on the nature of the problem LI Semi coupled analysis Q Fully coupled analysis In a semi coupled analysis for instance the structural response is influenced by the temperature field but the thermal response is independent of the structural response or vice versa In such a case the thermal analysis is performed prior to the structural analysis and 302 Chapter 7 either a single or series of nodal temperature tables are created These are read during the structural analysis at the required loadcase or time step In a fully coupled analysis the thermal and structural analyses must be performed simultaneously with a continuous transfer of information between the two analyses For instance in addition to modelling the influence of the thermal field on the structural response the effect of the structural response on the thermal field is represented
603. y is used to control the degree of dilatancy Associated plastic flow is achieved if y 1 but it has been found that y values in the range 0 1 to 0 3 were required to match experimental results Generally y is set to 0 1 but for high degrees of triaxial confinement 0 3 provides a better match to experimental data e The constant m can be obtained from experimental data from tests in which shear is applied to an open crack The default value for m is taken as 0 425 but it is considered that a reasonable range for m for normal strength concrete is between 0 3 and 0 6 However it was found that a low value of 0 3 could lead to second cracks forming at shallow angles to the first due to the development of relatively large shear forces e tis assumed that there is a crack opening strain beyond which no further contact can take place in shear ery where eg 1s a multiple of 1 e ep May Eo Trials suggest that when concrete contains relatively large coarse aggregate 1 e 20 to 30mm a value of Mg in the range 10 20 is appropriate whereas for concrete with relatively small coarse aggregate i e 5 to 8mm a lower value is appropriate in the range 3 to 5 This variation is necessary because the relative displacement at the end of a tension softening curve related via the characteristic dimension to e0 is not in direct proportion to the coarse aggregate size whereas the clearance displacement is roughly in proportion to the coarse a
604. y some Lines or Points are selected the hole will be stretched by only moving the selected features Note Moving a hole actually deletes the original hole and recreates a new hole This means the feature numbers of the Points and Lines will not be maintained LI Copy Creates multiple holes within a Surface LI Delete Deletes the selected hole s The hole boundary lines may be deleted retained as Lines or used to create new Surfaces LI Delete All Deletes all holes from a selected Surface The hole boundary lines may be deleted retained as Lines or used to create new Surfaces 86 Chapter 4 Redefine Perimeter A Surface perimeter may be modified by selecting the Surface and the new boundary Lines The new Surface perimeter will be created from a closed loop of Lines formed from the old Surface perimeter and the new boundary Lines The perimeter of the Surface will be defined from the closed loop of Lines with the maximum number of segments If two possible loops of Lines have the same number of segments a additional Line from the existing Surface boundary should be selected to resolve the ambiguity 87 Modeller Reference Manual Sweeping Surfaces LI By Sweeping Defines a Surface by sweeping a selected Line through a transformation translation rotation mirror or scale Line 1 is swept using an X and Y translation A cylindrical Surface is defined by sweeping to create Surface 1 Line 1 through a rotation g Em
605. y the drop buttons click on the down arrow to the right of the cursor button Alternatively hold down the appropriate key whilst selecting using the normal cursor as follows The selection filters allow only specific objects to be ka Select Annotation M Mesh selection filter N Node selection filter B Edge selection filter F Face selection filter E Element selection filter A Annotation selection filter When a specific selection option has been chosen the on screen cursor will show a graphical representation of the chosen option See Appendix C Model Selection Shortcuts for a complete listing of the selection keys available Selecting coplanar neighbours After selecting a surface or element face the Select Coplanar Neighbours menu item can be selected from its context menu This provides a quick way to select a number of surfaces or 30 Chapter 2 element faces according to their alignment in relation to the selected surface or element face By specifying an angular tolerance all surfaces or element faces where the angle between the normals of adjacent surfaces or element faces lies within that tolerance will be added to the selection This is of particular use when defining a draping surface as used in composites analysis An option to ignore internal faces helps to ensure that when an element has faces that both lie within the angular tolerance only the external face is selected Advanced Select
606. you may assess the performance of the solution For more information refer to the Solver Reference Manual Creep Viscoelastic Analysis Nonlinear viscous behaviour occurs when the relationship between stress and strain is time dependent The viscous response is usually a function of the material properties stress strain and temperature history Unlike time independent plasticity where a limited set of yield criteria may be applied to many materials the viscous response differs greatly for different materials A creep viscoelastic analysis may be carried out using a linear or nonlinear material model within a nonlinear transient dynamic or thermo mechanically coupled analysis When carried out in a nonlinear analysis inertia effects are neglected and the time component is introduced 291 Modeller Reference Manual using viscous control When using viscous control automatic time step calculations are only available when creep is included in the analysis LL Creep material properties are defined using the Attributes gt Material gt Isotropic Orthotropic menu item LI Viscoelastic material properties are defined using the Attributes gt Material gt Isotropic Orthotropic menu item Eigenvalue Analysis An Eigenvalue extraction analysis is the extraction of the natural modes of vibration of a structure or a natural frequency analysis It can also be used to solve the following problems Q Buckling load analysis A linear analysis which

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