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Prefem - DNV GL

1. LINEAR DEPENDENCY select nodes load case load type select geometr Sx yp g y END PROPERTY LOCAL COORDINATE BEAM select lines MATERIAL material name POINT MASS select points SECTION section name THICKNESS select surfaces TRANSFORMATION trnam PURPOSE The command deletes properties defined by the PROPERTY command PARAMETERS Prefem 5 95 See the PROPERTY command for explanations of the various property types For select geometry select surfaces select lines select points and select nodes see Section 5 1 and Section 5 2 NOTES Deleting LINEAR DEPENDENCY will change the boundary condition to FREE An exception to this is the case where the boundary condition was defined as SUPER before the definition of the linear depend ency In such case the boundary condition will return to SUPER Parts of a load may be deleted by selecting only some of the load types and or selecting only some of the geometry subjected to the load DELETE PROPERTY TRANSFORMATION has the same effect as the DELETE TRANSFORMATION command Prefem 5 96 DISPLAY SESAM 01 JUN 2003 Program version 7 1 DISPLAY CONNECTOR BODY SURFACE LINE POINT GEOMETRY select geometry MESH SHAPE select shapes ELEMENT select elements NODE select nodes a This option is presently inactive PURPOSE The command displays the
2. PURPOSE The command copies and extrudes a 2 D geometry to form a 3 D geometry alternatively a 1 D geometry to form a 2 D geometry The geometry to copy and extrude must exist The command is organised as follows see also the command syntax above Select geometry to copy This may for example be the surfaces of a bulkhead which shall be copied one or several times to make additional bulkheads A prefix for the geometry names of the copies is given to enable identifying the copies later on Select geometry to extrude Points are extruded to lines lines to surfaces and surfaces to bodies Lines may for example be selected to be extruded to the skin and deck of a ship When extruding lines to sur faces also the points connected to the lines are extruded to lines A prefix for the names of the extruded geometry is given to enable identifying this later on Select the global cartesian or a specified cylindrical coordinate system for the copy extrusion operation The cylindrical coordinate system is defined by giving the cartesian coordinates of three points The ori gin of the cylindrical coordinate system a point on its z axis and a point defining its r axis or phi 0 plane Give the number of copies extrusions to make The corresponding number of vectors must be given either one by one or several at a time by the optional REPEAT n times command Having chosen the glo bal cartesian coordinate system the vectors
3. Shrunken elements and element thickness Colour coding of thickness and beams as solids SET GRAPHICS SHRINK FACTOR 0 7 SET GRAPHICS PRESENT FILL ELEM ON SET GRAPHICS PRESENT ELEMENT THICK LABEL COLOUR IDENTIFIC THICKNESS SYMBOLIC DISCRETE VALUES ABOVE 0 0 LABEL ELEMENT THICKNESS ON SET GRAPHICS PRESENT BEAM ELEMENT SECTION AS SOLID Figure 3 63 Display features 4 Labelling of nodes free yellow diamonds fixed Labelling of element normal the in plane axes are green diamonds super blue circles and boundary determined by the analysis program conditions LABEL ELEMENT NORMAL ON ABEL NODE SYMBOL ON ABEL BOUNDARY CONDITION SYMBOL ON Figure 3 64 Display features 5 SESAM Prefem Program version 7 1 01 JUN 2003 3 73 Loads may be displayed load case 1 is a line load Load case 2 is a normal pressure ADD DISPLAY LOAD 1 LINE LOAD ADD DISPLAY LOAD 2 NORMAL PRESSURE Figure 3 65 Display features 6 3 12 2 Checking the FE Mesh The CHECK MESH TOPOLOGY command is used to check whether it is possible to create a mesh for the whole or parts of the geometry model A mesh is not created The CHECK MESH TOPOLOGY command is convenient as it is significantly quicker than the MESH command The quality of the mesh is investigated using the CHECK ELEMENT SHAPE command There are options for checking for Maximum and minimum angl
4. Use GENERATE to create the geometry of the flat bottom GENERATE SURFACE A 1 2 1 6 1 2 1 8 END CYLINDRICAL 000001100 000 10 0 0 END O 90 0 END Use GENERATE to create the geometry of the cylindrical tank GENERATE SURFACE B 1 2 1 8 1 2 1 6 END CYLINDRICAL 000001100 1000 0900 END 0 0 12 END Use GENERATE to create the geometry of the spherical top GENERATE SURFACE C 12 18 12 1 6 END SPHERICAL 00 5 3205 001100 20 0 60 0900 END 00 30 END SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX A 5 Give surface thicknesses the thickness of the cylinder varies PROPERTY THICKNESS A 0 05 B LINEAR 2POINTS VARYING AP21 0 05 BP12 0 01 C 0 01 Set type of element SET ELEM TYPE SURF ALL SURFACES INCL SHELL 4NODES Define a shape and project the mesh of the spherical top onto it DEFINE POINT PC 0 0 0 0 5 3205 DEFINE SHAPE SPHERE SPH1 PC 20 SET PROJECTION C SPH1 Define boundary conditions PROPERTY BOUNDARY CONDITION AI11 BJ11 CJ11 FREE FIX FREE FIX FREE FIX GLOBAL AI12 BJ21 CJ21 FIX FREE FREE FREE FIX FIX GLOBAL AP11 FIX FIX FREE FIX FIX FIX GLOBAL AP21 FREE FIX FIX FIX FREE FIX GLOBAL AP22 FIX FREE FIX FREE FIX FIX GLOBAL CP12 FIX FIX FREE FIX FIX FIX GLOBAL Define and assign material to surfaces PROPERTY MATERIAL STEEL ELASTIC 2 1E11 0 3 7850 0 0 0 0 CONNECT MATERIAL STEEL ALL SURFACES INCLUDED Define loads case 1 i
5. PURPOSE The command defines a value varying linearly in two directions Three points define a projection plane The function can be viewed as a plane set off from the projection plane by the three values in the three points The value at any point in the projection plane and the extension of this plane will apply to any point on a line perpendicular to the plane and through the point in question PARAMETERS point 1 Name of the first interpolation point value 1 Value for the first interpolation point point 2 Name of the second interpolation point value 2 Value for the second interpolation point point 3 Name of the third interpolation point value 3 Value for the third interpolation point Example of use see Figure 5 7 LINEAR 3POINTS VARYING P1 3 P2 2 5 P3 1 Surface subjected to load Point node where value 1s sought Projection line normal to plane P1 P2 P3 Figure 5 7 Example of use of LINEAR 3POINTS VARY ING function Prefem SESAM 5 12 01 JUN 2003 Program version 7 1 LINEAR RADIUS VARYING LINEAR RADIUS VARYING centre point point 1 value 1 point 2 value 2 PURPOSE The command defines a value varying linearly with the radius about a given centre point The value is spec ified in two points One of the points can be the same as the centre point The value will be constant on any sphere with its centre at the centre point PARAMETERS centre point Name of the cent
6. Set type of element 4 node shell for all surfaces and 2 node beam for selected lines where there should be girders SET ELEMENT TYPE SURFACE ALL SURFACES INCLUDED SHELL 4NODES LINE EXTL14 EXTL24 EXTL15 EXTL25 EXTL17 EXTL27 BEAM 2NODES o oe Define and assign beam cross section PROPERTY SECTION GIRDER I 2 0 0 8 0 04 0 02 0 8 0 04 1 0 1 0 CONNECT SECTION GIRDER ALL LINES INCLUDED Specify eccentricity the girders flush with the plates PROPERTY ECCENTRICITY BEAM EXTL24 EXTL14 EXTL25 EXTL15 CALCULATED NEGATIVE Z OFFSET EXTL27 EXTL17 CALCULATED POSITIVE Z OFFSET Set maximum element length for all surfaces SET MAX ELEMENT LENGTH ALL SURFACES INCLUDED 4 Create a FE mesh for all lines and surfaces MESH ALL Set the mode in which a change in mesh involves re meshing SET DEFAULT ADJUST MESH ON END Adjust number of elements for the three short horizontal lines next to the blige SET NUMBEROF ELEMENTS LI12 COPL16 COPL26 1 o oe oec Define boundary conditions fixations PROPERTY BOUNDARY CONDITION A Boundary conditons for the three lines curves LI1 LI7 LI2 LI5 LI16 LI12 LI10 COPL22 COPL23 COPL20 COPL24 COPL21 COPL26 COPL25 FIX FREE FREE FREE FIX FIX GLOBAL B Boundary conditons for the vertical line in the bulkhead midship SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX A 3 LI4 LIO FREE FIX FREE FIX FREE FIX GLOBAL C
7. select geometry PART __ ALL SPRINGS DAMPERS INCLUDED a This option is presently inactive PURPOSE The command creates the FE mesh plus damper and spring elements The command is equivalent to the CREATE MESH command The MESH ADJUST command however does not create a mesh rather it adjusts the element division on lines making non meshable surfaces meshable A surface is non meshable if Prefem is incapable of creat ing a mesh on it which again may be because the transition from fine to coarse mesh is too abrupt Note that the command merely makes the surfaces meshable the resulting mesh may be distorted and therefore unacceptable The command may be used before or after meshing the geometry It should be noted that the process of adjusting the element division will normally affect surfaces neighbour ing the selected surfaces causing the mesh for these neighbour surfaces to be deleted In the general case any surface of the model may be affected and its mesh deleted Note The mesh adjusting function is implemented for surfaces only PARAMETERS name of geometry Give the names of lines surfaces or bodies to be meshed Wild card selection may be used see Section 3 9 3 and pre defined sets may be used see Section 3 9 4 Spring and damper element names see the DEFINE SPRING DAMPER commands may also be given involving such ele ments to be created ADJUST Adjust element division on lines to make
8. Model the geometry ofthe structure The geometry consists of points lines and curves surfaces and bod ies Give data determining the FE model element density and types etc The FE model consisting of elements joined together in nodes is automatically created Assign properties such as material data boundary conditions loads etc to the geometry These data are automatically transferred to the FE model SESAM Program version 7 1 Prefem 1 2 01 JUN 2003 nevertheless also used for a complete model made by Prefem i e a first level superelement with no supernodes or super degrees of freedom is 1 L L L5 a p ee ee Oe Fen Y Wao Le a e a a A AA a SNY A AY A A Af Y a a i EEE CE Ew ES Cw FYIIIIJ ITITFYITI Input is interactively entered in Prefem The user is guided by prompts for data and graphics functions are available for visualising model data Data entered are logged on a command log journal file commands not changing the model for example a display command are by default not logged The log file can be used in a new Prefem session to regenerate the model A standard text editor can be used to modify the log file for the purpose of creating a modified model The log file is also a documentation and a back up of the modelling work Alternatively to interactiv
9. Projection of nodes created during meshing onto surfaces see the DEFINE SURFACE and SET PRO JECTION commands Defining geometry by determining the intersection line between two shapes or intersection point between three shapes see the DEFINE INTERSECTION and DEFINE POINT commands There are four basic shapes available see Figure 5 30 Figure 5 30 Basic shapes Additionally a free form shape being an interpolation between two sets of chained lines curves is available Each chain consists of a starting point and a sequence of lines arcs and or splines A number of straight lines between the two chains form twisted panels These panels constitute the shape see Figure 5 31 Each straight line is drawn between a pair of points on the two chains These two points are spaced at equal distances relative to the whole lengths of the two chains The spacings are made small enough to fulfil the following requirement The deviation between the secant from the previous to the new point and the curve itself should not exceed a coordinate tolerance This tolerance is set by the SET TOLERANCE COORDI NATES command Prefem 5 84 point PARAMETERS PLANE SPHERE CYLINDER CONE INTERPOLATION name point point2 point3 centre rrl r2 line1 line2 SESAM 01 JUN 2003 Program version 7 1 panels linel Figure 5 31 Interpolation shape Define a shape being a plane Define a shape being a sphere Define a shape being
10. DEFINE COORDINATE SYSTEM CY1 CYLINDRICAL start xyz z axis xyz r axis xyz DEFINE POINT P1 lt USE LOCAL COORDINATE SYSTEM CY1 R r PHI phi Z z gt The parameters start xyz z axis xyz and r axis xyz are the three sets of coordinates defining the origin Z or pole axis and 0 plane Compared with the description for updating point coordinates in Section 3 3 1 the options X Y Z DX DY and DZ are replaced by R PHI Z DR DPHI and DZ for cylindrical coordi nate systems For spherical coordinate systems the options are R PHI THETA DR DPHI and DTHETA Loads and boundary conditions may be given in a pre defined named coordinate system by entering the command alternative LOCAL COORDINATE SYSTEM followed by the name of the system The loads and boundary conditions are then given in the R Z system for cylindrical coordinate systems and in R O for spherical systems Coordinate systems defined are printed on the screen by the command PRINT TRANSFORMATIONS 3 12 Verifying and Checking the Model The importance of checking and verifying both the geometry model and the FE model is self evident and should be conducted according to the users best judgement The following sections describe some useful features for this purpose In addition to the features presented below the PRINT command providing more exact information than the DISPLAY command is useful for verifying and documenting the model 3 12 1 Display and Plot Features Figure
11. PROPERTY LOAD 1 GRAVITY GLOBAL FLEXIBLE PART CONTRIBUTION 0 0 0 0 9 81 PROPERTY LOAD 2 RIGID BODY ACCELERATION GLOBAL 0 0 0 0 9 81 0 0 0 0 0 0 END x RIGID BODY ACCELERATION GRAVITY Figure 5 42 RIGID BODY ACCELERATION compared with GRAVITY SESAM Prefem Program version 7 1 01 JUN 2003 5 167 PROPERTY LOAD load case RIGID BODY VELOCITY RIGID BODY VELOCITY GLOBAL ivx ivy ivz IVIX ivry ivrz END VX VY VZ VIX vry VIZ PURPOSE The command defines a velocity field The rotational velocity components refer to the axes of the cartesian coordinate system of the model This feature is presently not available in the analysis program Sestra PARAMETERS GLOBAL The cartesian coordinate system of the model is used VX VY VZ VIX Vry VIZ The velocity components The unit of the rotational velocity is radians second ivx ivy ivz ivrx ivry ivrz Imaginary velocity components Entering END implies that the load is real Prefem SESAM 5 168 01 JUN 2003 Program version 7 1 PROPERTY LOAD load case TEMPERATURE ONE VALUE EACH NODE temp diff TEMPERATURE select geometry TWO VALUES ON SHELL temp diffl temp diff2 VALUE ON NEIGHBOURING ELEMENTS _ temp diff PURPOSE The command defines initial strains due to thermal expansion by a given temperature difference between the present temperature and a refere
12. The required degree of accuracy FINE will require more calcu lation time This option overrules the mesh corner setting by the SET MESH CORNER TYPE command A maximum mesh corner angle is set If the mesh corner angle is greater than the given value then the surface will be meshed with not corner at this point irrespective of whether the point has been defined as MESH CORNER or not The maximum mesh corner angle Determines whether pairs of triangles are optimised by splitting the quadrilateral on the shortest diagonal Not used for solid el ements Switch the optimisation on and off SESAM Prefem Program version 7 1 01 JUN 2003 5 245 SOLID ELEMENT SHAPE Set a parameter influencing solid element shapes sol shape param Parameter influencing the iteration used to calculate the nodal coordinates in the interior of the bodies Legal values are be tween 0 0 and 0 5 Default value is 0 5 SURFACE ELEMENT SHAPE Set a parameter influencing surface element shapes surf shape param Parameter influencing the iteration used to calculate the nodal coordinates Legal values are between 0 0 and 1 0 Default val ue is 0 7 Prefem SESAM 5 246 01 JUN 2003 Program version 7 1 SET NAMING DEFAULT MASK mask NAMING CUT PURPOSE The command is used for determining geometry names resulting from use of the CUT command When cutting geometry new geometry names will automatically be created by the program
13. and greater than bracket commands to subtract 2 from the Z coordinate like this lt DZ 2 gt At this stage the bulkhead should be complete and appear as shown in Figure 3 8 apart from the viewing angle Prefem SESAM 3 12 01 JUN 2003 Program version 7 1 The bulkhead is completed The complete geometry shown with dashed lines Figure 3 8 Tutorial the initial surface has been cut twice corner rounded bilge and point moved The bulkhead should now be extruded to form the complete midship section Give the EXTRUDE com mand proceed as follows Select the three surfaces to copy to make the two frames all surfaces but the upper right one To select multiple surfaces start and conclude the selection by the left and right parentheses these are commands on their own Select a surface by clicking the right mouse button repeatedly on a border line until the proper surface is highlighted whereupon the left mouse button is clicked do not move the mouse during this operation Such selection is also described under the explanation of the Graphic display area in Section 3 1 When concluding the selection by the right parenthesis command the three surfaces will automatically be displayed Give prefix for names of copies of geometry e g COP Select the lines to extrude to make the deck and skin To select multiple lines start and conclude the selection by the left and right parentheses Select by clicking
14. fingers have been doubled to get correct areas of the stiffeners The stiffener heights are represented by the sum of the fingers The more fingers the more correct representation Figure 3 57 Layered element with interwoven fingers for plate with orthogonal stiffeners Layered elements are defined as follows e Define the material of both plate and stiffeners by the PROPERTY MATERIAL material name ELAS TIC command Define the bar sections of the stiffeners by the PROPERTY SECTION section name BAR command Define the layers DEFINE LAYERED layered name PLATE plate data STIFFENER stiffener data The PLATE and STIFFENER alternatives are repeated to construct the complete layered element This determines the number of layers that the layered element is comprised of Select the appropriate type of layered element by the SET ELEMENT TYPE command Define local coordinate system by the PROPERTY LOCAL COORDINATE SURFACE command If this command is omitted a default local coordinate system is employed Connect the layered element to the appropriate surfaces by the CONNECT LAYERED command Create the mesh by the MESH command 3 10 3 Axi symmetric Elements Certain requirements must be met when modelling an axi symmetric FE model In Sestra a cylindrical coor dinate system r z 0 is used and the model consists of elements in the r z plane which corresponds to mod elling in the x y plane in Prefem
15. i e the view point The eye will be positioned on the line through the origin and the point eyex eyey eyez at an infinite distance from the origin thus resulting in a parallel projection By chang ing the eye direction the model is displayed from different an gles Giving DEFAULT rather than a point sets the viewpoint back to what it was when entering Prefem the setting in Man ager You may find that rotating the model interactively is more effi cient see Section 3 1 Switch ON and OFF hidden display mode Hidden mode re quires more computation time For large models combined with limited computer resources this may be a problem The hidden mode is only relevant for display of FE mesh i e it has no ef fect on display of geometry model Note that Shift Esc will abort a time consuming display see Section 4 2 1 Switch between graphical option ON and line mode option OFF user interface See Chapter 4 SESAM Program version 7 1 NUMERICAL VALUES PLOT FILE PRESENTATION PROPERTY SELECTION AUTO ROTATION MODE SCALE SHRINK FACTOR SIZE SYMBOLS VIEWPORTS Prefem 01 JUN 2003 5 225 Choose format and number of decimals for numerical values displayed See separate explanation of the command Set name of plot file Any number of plots may be sent to the same plot file If a new plot file name is given then the previous one is closed Note that if you want to import a plot into a word proc
16. 01 JUN 2003 Program version 7 1 PROPERTY INITIAL VELOCITY INITIAL VELOCITY select geometry fx fy fz mx my mz GLOBAL TRANSFORMED trnam PURPOSE The command specifies the values of an initial velocity for nodes This is relevant for a dynamic analysis only PARAMETERS select geometry fx fy fz mx my mz GLOBAL TRANSFORMED trnam Select geometry See Section 5 1 on how to perform a selection Initial velocity in the X direction Initial velocity in the Y direction Initial velocity in the Z direction Initial rotational velocity about the X axis given in radians per second Initial rotational velocity about the Y axis given in radians per second Initial rotational velocity about the Z axis given in radians per second The values refer to the cartesian coordinate system of the model The values refer to a transformation of the cartesian coordinate system Name of a previously defined transformation SESAM Program version 7 1 Prefem 01 JUN 2003 5 137 PROPERTY LINEAR DEPENDENCY GENERAL NODE DEPENDENCY LINE LINE DEPENDENCY LINEAR DEPENDENCY RIGID BODY DEPENDENCY TWO NODE DEPENDENCY PURPOSE TWO POINT DEPENDENCY The command defines the displacements of selected nodes to be linearly dependent of displacements of other selected nodes See Section 3 5 8 for some general information on how to u
17. ALL TRANSLATIONS ONLY DEPENDENT SELECTED 6 NON DEPENDENT PURPOSE The command defines linear dependencies between all or selected d o f s of several nodes and a single node The dependent nodes are in this way forced to follow the displacements of a single node as a rigid body motion PARAMETERS select geometry point ALL TRANSLATIONS ONLY SELECTED DEPENDENT NON DEPENDENT Select geometry to be dependent See Section 5 1 on how to perform a selection The name of the point of the independent node All d o f s of the dependent nodes are linearly dependent of the corresponding d o f s of the independent nodes Only the translational d o f s of the dependent nodes are linear ly dependent These translational d o f s are however depend ent on all six d o f s of the independent node I e the rotations of the independent node also contribute The d o f s to be dependent are to be selected individually The d o f in question of the dependent nodes is dependent of the corresponding d o f of the independent nodes The d o f in question of the dependent nodes is not dependent ofthe corresponding d o f ofthe independent nodes nor of any other d o f Prefem SESAM 5 142 01 JUN 2003 Program version 7 1 PROPERTY LINEAR DEPENDENCY TWO NODE DEPENDENCY TWO NODE DEPENDENCY dep node indep nodel indep node2 ee eta FORCE
18. DNY SESAM USER MANUAL Prefem Preprocessor for Generation of Finite Element Models DET NORSKE VERITAS SESAM User Manual Prefem Preprocessor for Generation of Finite Element Models June Ist 2003 Valid from program version 7 1 Developed and marketed by DET NORSKE VERITAS DNV Software Report No 95 7014 Revision 3 June Ist 2003 Copyright 2003 Det Norske Veritas All rights reserved No part of this book may be reproduced in any form or by any means without permission in writing from the publisher Published by Det Norske Veritas Veritasveien 1 N 1322 Hovik Norway Telephone 47 67 577 99 00 Facsimile 47 67 57 72 12 E mail sales software sesam dnv com E mail support software support a dnv com Website www dnv com If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of Det Norske Veritas then Det Norske Veritas shall pay compensation to such person for his proved direct loss or damage However the compensation shall not exceed an amount equal to ten times the fee charged for the service in question provided that the maximum compensation shall never exceed USD 2 millions In this provision Det Norske Veritas shall mean the Foundation Det Norske Veritas as well as all its subsidiaries directors officers employees agents and any other acting on behalf of Det Norske Veritas 1 1 1 2 1 3 1 4 2 1 2 2 2 3
19. GRAY LOAD VALUES LOCATE LINES GREEN COLOUR MATERIAL NAME MEDIUM MESH ORANGE MESH CORNERS NODE NUMBERS RED NODE SYMBOLS POINT NAMES VIOLET POINTS DARK SUPER NODE SYMBOLS WHITE SURFACE NAMES YELLOW PURPOSE The command sets colour for lines names numbers and symbols Prefem 5 227 The command also sets multiple colours for load arrows The command SET GRAPHICS PRESENTA TION LOAD ARROW not CONNECTED ARROWS is required to use this feature PARAMETERS LOAD VALUE LEVELS number of levels BODY NAMES BOUNDARY CONDITIONS ELEMENT NUMBERS Set number of differently coloured load value levels Number of different load value levels Set colour for body names default colour is white Set colour for boundary condition symbols default colour is medium blue Set colour for element numbers default colour is medium blue Prefem 5 228 GEOMETRY LINES LINE NAMES LOAD VALUES LOCATE LINES MATERIAL NAME MESH MESH CORNERS NODE NUMBERS NODE SYMBOLS POINT NAMES POINTS SUPER NODE SYMBOLS SURFACE NAMES BLACK WHITE BLUE YELLOW LIGHT MEDIUM DARK SESAM 01 JUN 2003 Program version 7 1 Set colour for geometry lines default colour is medium green Set colour for line names default colour is medium red Set colour for load values default colour is medium green Set colour for lines appearing when using the LOCATE com mand default colour is medium green Set colour for ma
20. P will list all legal commands starting with P e two dots will execute the input data before and subsequently abort the current command The program is thereafter ready for more commands If the data before the is incomplete it will be dis carded lt two commas will cause one default parameter to be accepted May be useful when editing a com mand input file 5 semicolon will cause default parameters to be accepted until the end of the parameter group or until there is no default provided Text containing blank characters has to be enclosed within single quotes this is a text percentage sign at the beginning of a line is used for entering a comment Comments will be logged together with commands on the command log file see Section 4 1 5 Note that the program will occasionally log information on the command log file this will appear as comments in between data and comments entered by the user The program information is preceded by two percentage signs to distinguish it from the user s own comments This makes it easy to strip a command log file for program information in connection with creating a command input file any fairly good editor will have a macro functionality or similar enabling you to locate and remove all lines with Moreover comments preceded by will not be logged on the command log file to avoid irrelevant l
21. UNION WITH SUBTRACT BY INTERSECTION WITH A sequence of operations may be performed within the DEFINE SET command and once a set has been defined it may be changed by the CHANGE SET command in which the same operations are available Within each operation bodies surfaces lines etc are referred to by their explicit names or by wild card names see Section 3 9 3 It 1s important to keep in mind that the operations are performed in the order given and that one operation may undo a previous operation The use of wild cards combined with defining sets is a powerful feature that can be used both for defining the model and verifying it The user is advised to study this feature Sets consisting of elements and nodes may also be defined Such sets will however rely on the result of the automatic meshing A minor change in the mesh may result in new node and element numbers and the con tents of the sets will change Therefore defining sets consisting of geometry is generally the best approach An example DEFINE SET SET1 e SSeS sist The set is yet empty UNION WITH Su E Geometry is now being included in the set SURFACES S1 S2 S3 BODIES B1 B2 END Qo oec mme The set now contains 3 surfaces and 2 bodies END OTSESE DERRER Now display the lines of the bodies and surfaces in SET1 DISPLAY LINES SET1 3 10 Defining Special Element Types Most elements are created simply by setting appropriate type of elemen
22. 1 V12V21 d21 v2 Ey A v12V21 V12 Ep 1 V15V51 d22 E 1 v12V21 d31 d32 0 d33 Gi The material constants Young s modulus and Poisson s ratio v in the two directions are related as fol lows V21 E1 V1 E SESAM Prefem Program version 7 1 01 JUN 2003 5 179 PROPERTY MATERIAL material name ANISOTROPIC 3D SHELL ELEMENT 3D SHELL ELEMENT ql q2 q3 rho nlay thick angle d11 d21 d22 d31 d32 d33 d41 d42 d43 d44 d51 d52 d53 d54 d55 dampl damp2 alphal alpha2 nlay PURPOSE The command specifies the data for either an anisotropic or orthotropic material for higher order 6 and 8 node shell elements and for sandwich elements 6 and 8 node The anisotropic material properties are specified in a material coordinate system The first axis of the mate rial coordinate system is determined by projecting a vector Q onto the element plane and optionally rotate this axis a given angle around the normal to the element plane The second material axis lies in the element plane and is perpendicular to the first axis The third material axis is normal to the element plane The sandwich element a multilayered shell element comprised of normally three but in principle any number of layers through the shell thickness is defined by first specifying number of layers and thereafter givin
23. Boundary conditons for the end points of the centre line girder COPP26 POL FIX FIX FREE FIX FIX FIX GLOBAL D Boundary conditons for two points in the deck centre line COPP25 PO2 FIX FIX FIX FIX FIX FIX GLOBAL Define two load cases PROPERTY LOAD 1 COMPONENT PRESSURE EXTS13 EXTS23 EXTS12 EXTS22 GLOBAL 0 0 0 0 500 0 END MIDDLE SURFACE END LOAD 2 NORMAL PRESSURE EXTS10 EXTS14 EXTS20 EXTS24 EXTS11 EXTS21 EXTS15 EXTS16 EXTS25 EXTS26 LINEAR 2POINTS VARYING PO3 0 0 PO10 380 0 END MIDDLE SURFACE END Delete the current mesh DELETE MESH ALL For selected surfaces Change the direction of the load by changing the rotation of the surfaces CHANGE ROTATION OF SURFACE EXTS21 EXTS11 o oe oe Re create the mesh MESH ALL The model is now complete Prefem SESAM APPENDIX A 4 01 JUN 2003 Program version 7 1 A2 Cylindrical Tank with Flat Bottom and Spherical Top This example shows how to use the GENERATE command to model a cylindrical tank with flat bottom and spherical top Three GENERATE commands are used the last two adds to the former ones without duplicat ing existing geometry The model is shown in Figure A 1 z N NI CRLF VA YAT Si LRER SETS EK N 30 2 geometry FE mesh load case 1 load case 2 Figure A 1 Display of geometry with point line and surface names plus FE mesh plus loads
24. CORNERS options involves that all points surrounding the surface will be mesh corners Note You may skip giving information on mesh corners not mesh corners when defining the sur face as this may easily be defined later on by the SET MESH CORNER TYPE command Note You may even skip giving information on mesh corners not mesh corners altogether as the automatic mesh creation will optionally overrule mesh corner settings in corner points where the angle is larger than a certain value The default setting is such that all corners larger than 150 will be not mesh corner irrespective of the mesh corner not mesh corner setting PARAMETERS name User given name of the surface shape Name of a previously defined shape onto which the nodes cre ated for the surface will be projected For plane surfaces this en try is omitted For curved surfaces omission of a shape for projection may not give the desired mesh see Section 3 4 5 on this first line name Name of the first of two previously defined borderlines curves spanning a surface opposite line name Name of a previously defined borderline curve opposite the first one MESH CORNERS Points will be mesh corners SESAM Prefem Program version 7 1 01 JUN 2003 5 89 NOT MESH CORNERS Points will be not mesh corners line name Names of previously defined borderlines curves The lines curves must be given consecutively so that each line curve giv en adjoin the previous one The last line cu
25. EL EL X X Z X Y Z 1 1 0 126 0 379 1 000 0 126 0 379 1 000 2 2 0 126 0 379 1 000 0 126 0 379 1 000 3 3 0 126 0 379 1 000 0 126 0 379 1 000 4 4 0 126 0 379 1 000 0 126 0 379 1 000 5 5 0 000 0 063 0 547 0 000 0 063 0 547 6 6 0 000 0 063 0 547 0 000 0 063 0 547 7 7 0 000 0 063 0 547 0 000 0 063 0 547 8 8 0 000 0 063 0 547 0 000 0 063 0 547 9 9 0 000 0 063 0 547 0 000 0 063 0 547 10 10 0 061 0 017 0 547 0 061 0 017 0 547 11 11 0 063 0 006 0 547 0 063 0 006 0 547 12 12 0 063 0 006 0 547 0 063 0 006 0 547 13 13 0 061 0 017 0 547 0 061 0 017 0 547 Prefem 5 126 01 JUN 2003 PROPERTY PROPERTY BOUNDARY CONDITION CHANGE ECCENTRICITY BEAM HINGE INITIAL DISPLACEMENT INITIAL VELOCITY LINEAR DEPENDENCY LOAD LOCAL COORDINATE BEAM LOCAL COORDINATE SURFACE MATERIAL POINT MASS SECTION THICKNESS TRANSFORMATION PURPOSE SESAM Program version 7 1 The command defines properties such as thicknesses materials boundary conditions loads etc The properties are assigned to geometric entities such as points lines surfaces and bodies The properties are automatically transferred to the element mesh i e the nodes and elements PARAMETERS BOUNDARY CONDITION CHANGE ECCENTRICITY BEAM HINGE INITIAL DISPLACEMENT INITIAL VELOCITY LINEAR DEPENDENCY Define boundary conditions fixations of
26. For example cutting a line will yield two lines of which one will be given the original name of the line and the program will determine a name for the other By default the program will choose names like POi for points LIi for lines etc where i is a number Provided the GENERATE command or at least the naming system of that command has been used the SET NAMING command opens for maintaining this system for new geometry names See the GENERATE com mand for information on this naming system For example if there exists a line between the two points AP11 and AP13 and this line is cut then a new point is created The SET NAMING CUT command allows this point to be named AP12 rather than the default name POI Another example The line between the two points AP11 and AP12 is cut In this case there is no space in the numbering system as in the previous example This is solved by employing an extended numbering sys tem OAIB2C3D4ES5F6G7H8I19J The SET NAMING CUT command allows the new point to be named AP1B rather than the default name POi If a line between the two points AP11 and APIB is cut then a name following this extended system cannot be established because there is no space in the numbering system a default name PO1 is used in such a case A so called mask name is specified by the user to force new names to follow the naming system The mask name for the two examples above will be amp amp lJ where the first amp rep
27. For orientating spring to ground and damper to ground elements For copying geometry Coordinate systems of either cylindrical or spherical type are used For defining point coordinates By the GENERATE command note that the GENERATE command will unless referring to an exist ing coordinate system implicitly define a coordinate system For defining boundary conditions and loads radial and circumferential boundary conditions are for example easily defined by referring to a cylindrical or spherical coordinate system SESAM Prefem Program version 7 1 01 JUN 2003 2 13 2 11 Auxiliary Features There are some auxiliary features available for making the modelling easier and for verifying the model these are briefly presented below DEFINE SET may be used to define a named set selection of the geometry this set may then be referred to whenever reference to existing geometry is required DEFINE PARAMETER may be used to give a named parameter a value this parameter may then be referred to when e g defining point coordinates using the update mode see Section 3 3 1 The model may be displayed in different ways using the DISPLAY command and plotted sent to printer or file using the PLOT command Other commands that may be used in conjunction with displaying and plotting are LABEL ZOOM ROTATE LOCATE and SET GRAPHICS Alternatively to entering these commands there are several so called direct access buttons
28. MASS ELEMENT ONE NODE Figure 2 3 Graphical illustration of SESAM s element types Prefem SESAM 2 8 01 JUN 2003 Program version 7 1 2 6 Property Definition Material data beam cross sections plate thicknesses boundary conditions loads etc are so called proper ties that are assigned or connected to the relevant geometry by referring to the appropriate geometry names The properties will automatically be transferred to the FE model irrespective of whether the properties are defined before or after the FE mesh creation Most properties are defined and assigned to the relevant geometry by one command PROPERTY The fol lowing properties however are first defined command PROPERTY and secondly assigned to the relevant geometry by the CONNECT command Material data Beam cross sections Layered element data often used for stiffened plate modelling Some properties may however also be assigned directly to nodes and elements after creating the FE mesh Note that these properties will disappear when the mesh is deleted 2 7 Constraints on Geometry and FE Model 2 7 1 Constraints on Geometry Two points are not allowed to have the same coordinates Two lines curves surfaces bodies are allowed to have exactly the same definition This will give double sets of nodes and is normally not the proper way of modelling see Section 2 3 for notes and Figure 3 32 for an illustration of this Acircular arc defined by
29. PURPOSE The command defines outside of surfaces for the benefit of load application See the SET INSIDE command for a full description SESAM Program version 7 1 SESAM Program version 7 1 Prefem 01 JUN 2003 5 251 SET PLOT ON COLOUR OFF FILE file prefix file name number CGM BINARY HGPL 2 PLOT FORMAT HPGL 7550 POSTSCRIPT SESAM NEUTRAL WINDOWS PRINTER ORIENTATION PORTRAIT PAGE SIZE A4 PURPOSE The command sets parameters for plotting The settings must be done prior to the PLOT command PARAMETERS COLOUR FILE file prefix file name FORMAT number CGM BINARY HPGL 2 HPGL 7550 POSTSCRIPT Switch ON or OFF colours The default is OFF Colours are only supported by CGM BINARY POSTSCRIPT and HPGL 2 Give this command after choosing format and before saving the plot file Set file prefix and name for the plot file Default is the same as for the model and command log file The file extension depends on the type of format The file prefix and name for the plot file Set the plot format See Section 4 1 6 for information on which format to choose A number corresponding to the plot format may alternatively be given but you will normally not know this The CGM Computer Graphics Metafile is chosen File extension is CGM A Hewlett Packard plot format File extension is HPG2 A Hewlett Packard plot format File extension is H
30. Prefem SESAM 5 16 01 JUN 2003 Program version 7 1 The value is 1 2 within limiting space and A A zero outside this implies that for elements z Pal cut by the planes a linear function from 1 2 to 0 0 will apply Shaded area is element mesh The value is 1 2 within limiting space and S o a 12 es zero outside with a discontinuity where the plane intersects the beam Figure 5 12 Example of use of VALUE BETWEEN function for 2 node beam element SESAM Prefem Program version 7 1 01 JUN 2003 5 17 ONLY BETWEEN ONLY BETWEEN point 1 point 2 value PURPOSE The command limits the application of a value or function to a specified space Outside the space no value is defined not the same as zero see below This function is not suitable for specifying variable thickness The application is limited to the space in between the two parallel planes normal to the line between the two points and through the points Note Be aware of the difference between this function and VALUE BETWEEN by studying the examples given for each PARAMETERS point 1 Name of the first limiting point point 2 Name of the second limiting point value Value or function The value is 1 2 within limiting space and ra E 12 pond e undefined outside this implies that for L Shaded area is element mesh elements cut by the planes no value will apply Figure 5 13 Example of use of ONLY BETWEEN f
31. Translate by giving displacements Translate by moving from a point to another point Displacements in the X Y and Z directions of the cartesian coordinate system of the model Name of points defining the translation Scale by given scaling factors in the X Y and Z directions Scaling factors in the X Y and Z directions All types of transformation are relevant for copying geometry Only the rotation and mirroring types of transformation are relevant for defining loads Only the rotation type of transformation is relevant for defining a boundary condition and orientating sprint to ground and damper to ground elements The command PROPERTY TRANSFORMATION also defines transformations but this can only define rotational transformations Prefem SESAM 5 92 01 JUN 2003 Program version 7 1 DELETE CONNECTOR CRACK AXIAL damper name DAMPER TO GROUND damper name GEOMETRY select geometry LAYERED layered name DELETE MASS ELEMENT ONE NODED mass element name MESH PROPERTY SET set name SHAPE shape name AXIAL spring name SPRING TO GROUND spring name TRANSFORMATION trnam a This option is presently inactive b This option is presently inactive PURPOSE The command deletes previously defined geometric entities properties and other data PARAMETERS DAMPER AXIAL TO GROUND damper name GEOMETRY select geometry Delete a damper el
32. and shortcut commands providing quicker access to the same functionality these are described in Section 3 1 The PRINT command is available for printing data on the screen or to a file As an alternative to the PRINT command the direct access button named Info allows quick printing of various information on the geometric model See the description of the direct access buttons in Sec tion 3 1 on this n addition to influencing the display of a model through SET GRAPHICS the SET command is used for several other purposes Deciding type of element to use the number of elements along the lines and their spacing element length ratio Setting various tolerances used for deciding match no match situations e g for coordinates Setting various control parameters for the mesh creation Destination and file name for print and plot of data Determining inside outside of surfaces in connection with application of loads 2 12 Short Description of Commands A short description of each main command of Prefem is given below ADD DISPLAY adds graphical information to the current display i e geometry FE mesh or loads CHANGE changes data such as geometry shapes properties transformations one node ele ments nodes etc CHECK checks the shape of elements created and mesh topology i e whether a FE mesh can be created or not CONNECT connects materials previously defined to geometry cross s
33. explicit assignment using the PROPERTY THICK NESS command thickness Thickness Prefem SESAM 5 220 01 JUN 2003 Program version 7 1 SET ELEMENT LENGTH RATIO ELEMENT LENGTH RATIO _ select lines EQUALLY SPACED ARITHMETRIC SEQUENCE starting point relative length first elem relative length last elem GIVEN RELATIVE starting point relative length of elem PURPOSE The command defines the length of the elements or element edges for selected lines The command is irrelevant for lines of type node line The element edge lengths may be equal linearly increasing decreasing and the individual elements ele ment edges may be given relative lengths The lengths relate to a starting point chosen by the user If more than one line is selected then the starting point will not be requested rather the first point according to the definition of the line is taken as the starting point Mid side nodes for higher order elements will always be in the midpoint of the element edge Except for node lines which also determine the position of mid side nodes PARAMETERS select lines Select lines See Section 5 1 on how to perform a selection EQUALLY SPACED All elements element edges will be of equal length ARITHMETRIC SEQUENCE The element edge length will vary as an arithmetric sequence starting point Point defining the starting point of the line for distributing the P lengths
34. from Ref 1 The expression for SHCENZ is taken from Ref 2 R 0 HW HZ TZ B TZ HW 2 SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX B 13 C TZ 2 PIQRT atan1 0 AREA TY HW BY TZ 1 PIORT R Y HW TY TZ BY 2AREA Z HW B TY TZ BY COUAREA D 6R 4 TY TZ JARQR TY TZ 2TY TZ E HW TZ Z F HW E RI Y TY RJ BY Y RK RI 0 5TY RL Z C TS TZ TL TY If TZ gt TY then BA BY H HW ALPHA TL 0 07 0 076R TS TS IY TY HW BY TZ 12 HW TY B ZY BY TZZ Cy 2 IZ HW TY TZ BY 12 HW TY RK TZ BY BY 2 Y IYZ RL TZ 2 Y SRS ORK TY 2 E WXMIN IX D WYMIN IY MAX Z HZ H WZMIN IZ MAX Y RJ SY E TY 2 SZ RJ TZ 2 SHARY IZ TZ SZ SFY SHARZ IY TZ SY SFZ Prefem APPENDIX B 14 01 JUN 2003 IYZ IYZ If web located in positive y then 4 SHCENY RK CY BY Y SHCENY RK Else CY Y SHCENZ RL CZ Z SESAM Program version 7 1 SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX B 15 B1 7 Pipe section B 1 7 1 Sectional Dimensions DY Outer diameter T Thickness of wall SFY Shear factor y direction SFZ Shear factor z direction Z r DY y Figure B 7 Pipe section B 1 7 2 Sectional Parameters Computed The expressions below for LX IY IZ WXMIN WYMIN WZMIN SHARY SHARZ SHCENY and SHCENZ are taken from Ref 1 DI DY 2T PI 4atan1 0 AREA P
35. line geometry regular rectangular mesh Figure 3 44 Mesh for an L shaped surface Prefem 3 44 01 JUN 2003 SESAM Program version 7 1 Note The mesh created for a surface with dent or concavity tends to be distorted You may need to cut the surface so as to split the dent to get an acceptable mesh See Figure 3 45 gt M this geometry may give better mesh this geometry may give distorted mesh B Figure 3 45 Mesh for a surface with dent or concavity 3 4 5 2 D Elements for Curved Surfaces The previous section explained various types of 2 D element meshes for plane surfaces This section deals with meshes for curved surfaces Unless all its borderlines curves lie in a plane a surface will be curved Generally the interior of a surface is not defined explicitly unless projected onto a shape Even in cases where all borderlines curves do lie in a plane the interior may be projected onto a surface as shown in Figure 3 46 Surfaces with borderlines curves forming a cylinder sphere will in certain cases yield cylindrical spherical element meshes even without projecting the surfaces onto cylindrical spherical shapes These cases are e When a regular mesh is created i e equal number of elements on opposite edges When regular or irregular meshes are created using a cylindrical spherical coordinate system The itera tion process creating the mesh will then be performed in the cylindrical spherical co
36. middle or outside of surfaces Reversing the inside and outside of a surface has the following effect also see Figure 3 68 For LINE LOAD PART LINE COMPONENT PRESSURE and NORMAL PRESSURE the area length for LINE LOAD and PART LINE to which the load is applied may change and thereby the load sum will change For NORMAL PRESSURE and HYDRO PRESSURE the direction of the load will also change Note The concept of inside and outside of surfaces has relevance for the application of loads only By default the outside of a surface is on the positive local z side see Figure 3 67 This default condition is changed by the SET INSIDE OUTSIDE commands These commands will however not change the rota tional order and thereby not the local z axis of the elements The user may find it more convenient to use either the CHANGE NORMAL OF SURFACE or the CHANGE ROTATION OF SURFACE command to maintain a consistency between inside outside and the local z axes Note The direction of the local z axis has no influence on the load application Note A surface can only have one setting of inside outside You cannot have different inside outside setting for different loads Note The evaluation of functions see Section 3 7 1 is based on nodal coordinates This means that while the thickness of a shell will influence the application of a load as illustrated in Figure Prefem SESAM 3 76 01 JUN 2003 Program version 7 1 3 68 it will not influenced the
37. of UMtS eniro eet tig a gue ar Rede e de Rs ante uieviess B 21 REFERENCHES ctaeeiethse egi eto uss a aoi nine eo khe sssri tod TEE HRS REA GI MR Pep ER deg M dicus REFERENCES 1 SESAM Prefem Program version 7 1 01 JUN 2003 1 1 1 INTRODUCTION 1 1 Prefem General Preprocessor for Finite Element Modelling Prefem is SESAM s preprocessor for general finite element FE modelling The models may be comprised of truss beam membrane shell and solid elements More specialised elements like spring damper and mass elements sandwich elements contact elements and axi symmetric elements are also available A model to be used for structural analysis is termed herein a FE model whereas a model to be used for hydrodynamic analysis is termed a panel model A panel model may in certain cases be equal to a FE model the same model is used for both structural and hydrodynamic analysis but normally it is somewhat differ ent Modelling a panel model will however in principle be the same as modelling a FE model References in this manual to the terms FE model and FE modelling should therefore also be understood as panel model and panel modelling Prefem is characterised by Easy interactive input combined with graphical and printed feedback for model verification Extensive data generation features A data management system allowing arbitrarily large models The modelling procedure consists of the following basic steps
38. select geometry Select geometry to be plotted See Section 5 1 on how to perform a selection ELEMENT Plot selected elements select elements Select elements to be plotted See Section 5 2 on how to perform a selection NODE Plot selected nodes Prefem 5 116 select nodes LOAD load case load type textline Al A5 NOTES SESAM 01 JUN 2003 Program version 7 1 Select nodes to be plotted See Section 5 2 on how to perform a selection Plot a selected load together with the element mesh See the ADD DISPLAY com mand for an explanation of the graphic presentation of the loads The load case to plot If a load case contains several load types line load normal pressure etc then only one of the load types may be plotted at a time Type of load for the load case to plot See the PROPERTY LOAD command for the different types of loads A line of text of maximum 24 characters If including blanks the line must be en closed by single quotes This is an example European standard paper formats sizes A4 is approximately 21 x 30 cm 8 3 x 11 7 inches A1 A2 etc have all the same width height relation being such that when cut in half parallel with the shortest side the width height relation remains the same A1 is by definition 1 m A2 is half of Al A3 is half of A2 etc This entry is dummy for other plot formats than SESAM NEUTRAL The default file name and prefix of the plot file are the same as for the model
39. the two upper lines the lines along the Y and Z axes and the arc the bilge Note that in order to be able to click the horizontal upper line the deck you must display the complete geometry by clicking the Direct access button Select Draw Geo Give prefix for names of extruded geometry e g EXT Give coordinate system in which the copying and extrusion shall be performed the global cartesian system Give number of copies extrusions 2 Give the two vectors defining the copying extrusion 15 0 0 and 18 0 0 Specify that lines are to extruded to surfaces The copied extruded geometry will automatically be displayed At this stage the geometry model should be complete and appear as shown in Figure 3 9 Rotate the model for example by clicking the Direct access button View Default a default set in Manager or by giving the command SET GRAPHICS EYE DIRECTION 1 1 1 0 0 5 SESAM Prefem Program version 7 1 01 JUN 2003 3 13 The geometry model is completed Figure 3 9 Tutorial the initial surface has been cut twice corner rounded bilge and point moved e Use the PROPERTY command to assign thicknesses to surfaces i e plates Since most surfaces skin bulkhead and frames have thickness 0 03 you may assign this thickness to all surfaces and thereafter assign thickness 0 02 to the four surfaces constituting the deck If you have a viewing angle as in Figure 3 9 selecting the deck surfac
40. 00000E 01 5 00000E 01 4 00000E 01 MID NORMAL PRESSURE LOADS LOAD CASE NUMBER 3 SURFACE NAME PRESSURE IMAG PART SIDE S1 8 5000E 00 MIDSIDE Print of nodal coordinates and other information Nodal coordinates are tabulated The X in column BOU CON informs that a boundary condition has been defined for that node see the next table for details The number in the column ND is the number of degrees of freedom for the node NODE COORDINATES BOU NO X Y Z CON ND 1 10 000000 0 000000 0 000000 X 6 2 10 500000 1 500000 0 000000 6 Prefem SESAM 5 124 01 JUN 2003 Program version 7 1 3 11 000000 3 000000 0 000000 6 4 11 500000 4 500000 0 000000 6 5 12 000000 6 000000 0 000000 X 6 6 8 000000 7 000000 0 000000 6 etc Print of boundary conditions for nodes The table gives details on nodal boundary conditions NODE TRANSF BOUNDARY CONDITIONS NO NO TX TY TZ RX RY RZ 1 FIXED FIXED FIXED FIXED 5 FIXED FIXED FIXED FIXED 9 PRESC PRESC PRESC 11 SUPER SUPER SUPER 1 5 LINEAR LINEAR LINEAR LINEAR LINEAR LINEAR 16 FIXED FIXED FIXED FIXED etc Print of element information The table provides details on the elements The column THICKNESS SECT NO informs about the thick ness of membrane and shell elements and cross section number for beam elements the Print of cross sec tional data shows that a number is assigned to each cross section name ELEMENT ELEMENT MATERIAL THICKNESS NO TYPE N
41. 1 The command controls the types of elements created by the MESH or CREATE MESH command The element types available are described in Section 2 5 PARAMETERS LINE SURFACE BODY select geometry element type NONE NOTES these elements Choose element type for lines 1 D elements Choose element type for surfaces 2 D elements Choose element type for bodies 3 D elements Select appropriate geometry See Section 5 1 on how to perform a selection Choose desired type of element See Section 2 5 Any element type previously chosen for this geometry is annulled Note that spring damper and mass elements are not set by this command See the DEFINE command for Most element types have six d o f s but some have only three truss and solid elements It is possible to use elements with six d o f s in combination with elements with only three d o f s The common nodes will have six d o f s SESAM Program version 7 1 01 JUN 2003 SET GRAPHICS ON AUTOMATIC OFF HARDWARE CHARACTER TYPE SOFTWARE COLOUR FINE CURVE DRAW NORMAL COARSE DEVICE device name GRAPHICS EYE DIRECTION eyex eyey eyez DEFAULT ON HIDDEN OFF ON INPUT OFF NUMERICAL VALUES PLOT FILE file prefix file name PRESENTATION ON PROPERTY SELECTION AUTO OFF GLOBAL AXES ROTATION MODE SCREEN AXES scale SCALE AUTO SHRINK FACTOR sh
42. 11 1 SESAM Prefem Program version 7 1 01 JUN 2003 3 47 Within the PROPERTY command there is a need for reference to geometrical entities by their names Refer to section Section 3 9 for a discussion on how to do this It is possible to assign certain properties directly to nodes e g PROPERTY BOUNDARY CONDITION and PROPERTY LINEAR DEPENDENCY Note that these will be deleted if the mesh is deleted and re created Therefore if properties need to be assigned to nodes and elements it is advisable to assign such properties at the very end of the modelling Properties are changed by either the CHANGE PROPERTY or the PROPERTY CHANGE command these commands are equivalent Properties are deleted by the DELETE PROPERTY command 3 5 1 Beam Cross Section The following cross sections are available and may be assigned to the truss element and the two and three node beam elements see Appendix B for illustrations of the cross sections Bar Box Channel Double bottom General T eL Pipe Un symmetrical I The sections are defined by the PROPERTY SECTION command and given unique names The cross sec tions are then assigned to the appropriate lines curves for which truss or beam elements are created This assignment is performed by the CONNECT SECTION command by referring to the section names and geometry line curve names Assigning sections to lines curves for which no truss or beam elements are cre ated has no consequ
43. 2 4 2 5 2 6 2 1 2 8 2 9 2 10 2 11 2 12 2 13 2 14 Table of Contents INTRODUCTION seostest s eon eee qus eve LrVe certe testo e oue ieoor deas kp Pte Desa ee QE T roas EUREN Orien 1 1 Prefem General Preprocessor for Finite Element Modelling sse 1 1 Prefem in the SESAM System cccccecscesscssccessecssecseceeeceeeeeseecscenseceseceseeeseeesecaeceeeeseseseeaeseaeeaeees 1 3 How to read the Manual iet eret tee bee P Ae I Pe d t deret tenes 1 5 SENSE p E 1 5 FEATURES OE PREEBEM eerte eode op eco enne ae ene oe aeo ehe dE pne cR Ny ERE Ve pire rta pepe i REN Rel en aEn 2 1 Modelling Principles t eerte ien ie t Eee Re canal date ate e HART E 2 1 Geometry Modelling reet etre E tives net Lr E E PEN REY tue eras 2 3 PE Modell Creations ee e EE PEUGEOT VER IU Ee POE e ESAE 2 4 Shapes Modelling Toolse yenne PERUENIRE UR EXARATIS 2 4 Element Library 5 3 petant eno Da INT rere aed ta testam e e UTE de 2 4 Property Definitio uie en eerie ettet derttit eve ide obtu Donuts Poe recie ode Mee gue ed ene 2 8 Constraints on Geometry and FE Model sse eene ener enne 2 8 2 1 Y Constraints on Geometry ete tibi pede ye tirer etos eite eis edu ride guo 2 8 2 7 2 Constraints on Deleting Geometry essssssssssssesee eene eene enne enne 2 8 2 7 3 Constramts onm FE Mesh ncn rrt ED I RR EET OTRAS PER Ea T ER Tuus 2 8 2 7 4 Constraints on Element Loading essssssssseses
44. 2 Sectional Parameters Computed essen nnne B 5 B31 3 Channel Section s ioi eee cete e ht Pee ere R Do Te e dea coe e DA v RR B 7 B1 3 1 Sectional Dimensions raens aana aaa aii ai ie B 7 B 1 3 2 Sectional Parameters Computed sess B 7 B 1 4 Double bottom section siie ean eseni R rai Ea esa E aE a aR nes B 9 B 1 4 1 Sectional Dimensions essere nennen ener B 9 B 1 4 2 Sectional Parameters Computed sse B 9 BA JL Orlfb Ssecton dette ect eie edet dash ete recte cout e depen br I cis tease de B 10 B151 Sectional Dimensions 5n eter ret e HR RAs B 10 B1 5 2 Sectional Parameters Computed sese B 10 B6 LEsectonzatoiosenotes tee ede eet vr ta d PI EE tee ettet ite B 12 B1 61 Sectional Dimensions sese B 12 B 1 6 2 Sectional Parameters Computed sese B 12 BiT Pipe ulmo B 15 B1 7 1 Sectional Dimensions esee enne nnne B 15 B 1 7 2 Sectional Parameters Computed sse B 15 B1 8 Un symmetrical sections nsoeie serine neediness eere enne eene nnne nennen nennen nennen B 17 B 1 8 1 Sectional Dimensions 4 4 Secs cede nes een rb RN eee eerte hes testas B 17 B 1 8 2 Sectional Parameters Computed sesssssssseseeeeeeenenennns B 17 jp CE EE B 20 B2 BEx mple 55 ote eee ete te E e San RO RE toate a de td B 20 B 2 2 Consistent Sets
45. 3 1 6 4 Figure 5 1 Example of linear function A parabolic variation along a line is defined by 40 96 LINEAR 2POINTS VARYING Pl 6 4 P2 3 1 2 0 61 Pl P2 Figure 5 2 Example of parabolic function 2 A linear function along a circle linear with respect to may be defined by PA 1 and PA2 defines the axis CYLINDER ANGLE VARYING PA1 PA2 P1 1 P2 O Notice that the function 1s extrapolated beyond P1 and P2 if PI necessary to cover all geometry to which the load applies PA2 is PAI above PAI Figure 5 3 Example of linear function along circle SESAM Prefem Program version 7 1 01 JUN 2003 5 9 A sinus function along a circle may be defined in two alternative ways 1 as a sinus function defined along the arc from P1 to P2 and 2 by taking advantage of the fact that a linear function projected onto a circle as shown in the figure will form a sinus function 1 SIN CYLINDER ANGLE VARYING PA1 PA2 Pl PI 2 P20 2 LINEAR 2POINTS VARYING P1 1 PA O In 1 notice how the value 7 2 is given for P1 using the built in parameter PI and with spaces separating the left and right parentheses and division symbol slash above PA 1 Figure 5 4 Example of sinus function along circle A wave force is an exponential function of depth A wave force on a cylinder may be given by multiplying the functions above by EXP LINEAR 2POINTS VARYING PA2 0 0 PA1 1 5 Multiplication of functions is perfor
46. 3 60 through Figure 3 65 show some of the features for displaying the model The user is advised to try out various display features while referring to the command description in Chapter 5 thereby gaining sufficient skill in displaying the model for verification and reporting purposes Note For large models the DISPLAY command may require some time During processing of the command you may use Shift Esc to abort it This will have no effect on the program execution Prefem SESAM 3 70 01 JUN 2003 Program version 7 1 apart from incomplete execution of the command in question and you may continue model ling This is available on PC only a similar feature is not available on other operating systems The PLOT command produces a plot file of the current display or sends the plot directly to the printer depending on the chosen plot format The SET PLOT command changes the format as well as the name of the plot file to produce The CGM BINARY plot format may be imported in MS Office Word and PowerPoint and even converted in these programs to an MS Office drawing thereby allowing it to be modified Problems importing a CGM file may be caused by lack of a graphics filter for CGM in your installation of Word and PowerPoint Go to a MS support or knowledge base web page to learn what to do The PostScript plot format is an ASCII file and may also be imported in MS Office Word and PowerPoint as well as other word processing programs The geometry
47. By default the boundary condition of all nodes is FREE The following boundary conditions can be given in parentheses the code used in print tables FREE blank Free to move FIXED FIXED Fixed at zero displacement PRESCRIBED DISPLACEMENT PRESC Will be given a prescribed displacement PRESCRIBED ACCELERATION PRESC Will be given a prescribed acceleration SUPERNODE SUPER Super d o f In addition linear dependencies will introduce boundary conditions see the command for this For the PRESCRIBED DISPLACEMENT ACCELERATION the actual displacement acceleration is given as a load using the command PROPERTY LOAD load case PRESCRIBED DISPLACEMENT ACCEL ERATION If no displacement acceleration is specified then the boundary condition PRESCRIBED DIS PLACEMENT ACCELERATION is equivalent to a fixation If the model is a superelement to be coupled with other superelements then SUPERNODE must be specified for the d o f s to couple If the superelement is to be rotated or mirrored then either all 3 translational d o f s all 3 rotational d o f s or all 6 d o f s must be specified as super The reason for this is that rotation and mirroring of a superelement SESAM Prefem Program version 7 1 01 JUN 2003 5 129 involve multiplying its stiffness matrix by 3 by 3 transformation matrices Such multiplication cannot be done unless the said requirement is fulfilled PARAMETERS select geometry Select ge
48. CORNER COMPLEMENT SECTOR CORNER centre pnt NONE DISTANCE pnt1 pnt2 END PURPOSE The command creates an arc with the specified radius and centre in the selected point The arc cuts the selected surface and its borderlines The arc cuts the surface into two surfaces Either or none of these sur faces may be deleted Alternatively to giving the radius explicitly it may be given as the distance between two arbitrary points Having selected which surface to delete or none you can exit from the command END or continue select ing more surfaces to cut These additional surfaces must be connected to the same point and the same radius is used for the arcs the radius is specified only once for all surfaces This functionality makes it easy to cre ate a circular hole where co planar surfaces meet in a point See Figure 5 28 Note The lines cut by the arc must be straight and connect to the centre point of the arc See Figure 5 29 Note The surface to be modified cannot have mesh PARAMETERS radius The radius of the arc to create DISTANCE The radius is the distance between two points pntl The first of two points defining the radius pnt2 The second of two points defining the radius centre pnt Centre of the arc to create surface Surface to cut by the arc it must be connected to the point cen tre pnt CORNER Delete the CORNER surface CORNER COMPLEMENT Delete the CORNER COMPLEMENT surface N
49. DER ee ra tr rre ove disputes 3 48 3o Thekness n eee ee o t ee ct e eed tu ete t beer EET eov due 3 49 3 5 5 Local Coordinate System for Surface Elements sse 3 49 3 5 6 Materials ettet eie e tuetur a etit te beset ect indu Et ERE I ate 3 49 3 5 7 Boundary Condition ice eee ee i e ep n tee e ra 3 50 3 5 8 Linear Dependency ies cete de Re ARE a r eee desde ee a ta ee exu e eaae 3 51 3 539 Poimnt Mass c eee HET chest RHET ee CE Ee ELO EU S OE I IER eds 3 52 35 10 Numeric Value Inp t eere ere eX ERU e E REEL eeu E 3 52 Defining Loads Vedi 3 52 Varying Value Input by Functions essen eene enne en nennen nnne 3 55 3 7 1 Evaluation of FUnctions cccccscsssssesscssecenececceescsesessteceascenecesesssesenesenecaeeceneeessensceatesaaes 3 59 Parametets oon on Mo ette eo b diei n Ite TRE tate Mode e e RUEDA ER tees 3 60 Selecting Geometry using Wild Cards and defining Sets sse 3 60 3 9 1 Graphical Selection of Geometry sse e ener nnne nnns 3 60 3 9 2 Line Mode Command Selection of Geometry essen 3 61 3 9 3 Using Wild Cards for Selecting Geometry sse 3 62 3 10 3 11 3 12 4 1 4 2 4 3 5 1 5 2 5 3 3 9 4 Defining and using Sets for Selection of Geometry sse 3 63 Defining Special Element Types cccecccccsccsccessccssceeeceeeeeseecsaeesaecaecnecseeeseceseseessecaecnseee
50. EYE DIREC 5 238 01 JUN 2003 SET JOURNALLING GRAPHICS ON JOURNALLING PRINT OFF PURPOSE mands PARAMETERS TION ROTATE LABEL ZOOM etc PRINT Switch for print commands ON Switch on OFF Switch off Program version 7 1 SESAM Prefem Program version 7 1 01 JUN 2003 5 239 SET MAX ELEMENT LENGTH MAX ELEMENT LENGTH select lines size PURPOSE The command defines the maximum size of elements element edges for a line or a group of lines See Section 3 4 for more information PARAMETERS select lines Select lines See Section 5 1 on how to perform a selection size The maximum element size NOTES See also the SET NUMBEROF ELEMENTS command Prefem SESAM 5 240 01 JUN 2003 Program version 7 1 SET MESH COORDINATE SYSTEM select geometry coord name COLLAPSED EDGE COLLAPSED QUARTER POINT EDGE CORNER CUT CORNER LARGE CUT CORNER NOT CORNER SMALL CUT CORNER TRIANGULAR BOTH NONE CORNER TYPE surface name point name TRIANGULAR BOTH ONE TRIANGULAR BOTH TWO MESH TRIANGULAR ELEMENT TRIANGULAR POST NONE TRIANGULAR POST ONE TRIANGULAR POST TWO TRIANGULAR PRE NONE TRIANGULAR PRE ONE TRIANGULAR PRE TWO EDGE RECTANGULAR surface line number of elements METHOD version number VERSION LATEST a This option is presently inac
51. INTO SUPER indep nodel FORCE INTO SUPER indep node2 PURPOSE The command defines linear dependency between a node and two other independent nodes The nodes are selected by referring directly to the node numbers This specification will be lost with a DELETE MESH command If possible it is therefore generally better to use the TWO POINT DEPENDENCY option All d o f s of the dependent node are made linearly dependent of the corresponding d o f s of two independ ent nodes The displacement of the dependent d o f s will be Idep FindepI D Tindepz 1 D where D is a dependency factor given by the user The program will compute a default value for B based on the projection of the dependent node onto the line between the two independent nodes See Figure 5 39 Normally the two node dependency is used when the dependent and the two independent nodes lie on a straight line oe dependent node b B b atb independent node 1 DE RUD CR independent node 2 Figure 5 39 Two node linear dependency the dependency factor D PARAMETERS dep node Node number of the dependent node FORCE INTO SUPER Make the d o f s of the independent node super See Section 3 5 8 for an explana tion of the relevance of this option indep nodel Node number of the first independent node indep node2 Node number of the second independent node beta Linear dependency factor SESAM Prefem Program version 7 1 01 JUN 2003 5 143 PROPER
52. OO NOS 5 211 Sol P 5 212 SET COMMAND ANPUT FILE alere ete e teer deis cei Bas 5 215 SET DEREAUET eite tr tht tesdo ive este ele iu le es A SEEN e stints 5 216 SET ELEMENT EENGTHSRA TIO iet teet eee re ioe A te oes 5 220 SET EBEEMENTZT Y PE itn iore rro rh n e CO eat Oe adn 5 222 SET GRAPHIGS 5 inscite sete tue SE ba piece eiecti E es 5 223 SEDI GRAPHIGS COEQOVUR ettet etin cet ta cota Ceo Fe Y I VII edet et eue rele PUITS 5 227 SET GRAPHICS NUMERICAL V ALUES 10 0 ceccccceccccccesssecesssseccesesececssseeccsssseecsesseecsessseeesenaes 5 229 SET GRAPHICS PRESENTATION cccccccccccccssccccsssscccceessecceessecessseeecessseecsesseeeessssecesesecensnss 5 230 SET GRAPHICS SIZE SYMBODLS ccccccccsccccsssscccssssccccssssccesssssessssssecsssssecsssssseessusseesssaseessnes 5 234 SELINSIDE OUTSIDE kd eee i tete een euo Coo eue er eee dea er eere etr testes eque 5 236 SETJOURNATLEEINGI 5 3 2 2 0 2 05 iste ED TD HET e need e TIT PN RE IUTS 5 238 SET MAX ELEMEN T LENG TH iii cett bh E ER E PE DERE 5 239 SETSNIBSTLG 2 ehe teret etse vet eet ee eee edere do imos ode deese Cot scie 5 240 SET MESH CORNER NOT MESH CORNER eene ene enne eren ee nene ee eene en nnns 5 243 SET MEBSH PARAMETERS erret ether Pee eee eden ee Ene erae ee De oe Ee EEANN AAAA 5 244 SET NAMING HZ nb eise ie A RE d bete 5 246 SET NOT MBSH CORNBR 3 asi bestes cie bea bebe i eme b ree i aa a 5 248 SET NUMBEROF ELEM ENTS cccc
53. P2 define point producing the same SX Figure 3 21 Cutting geometry Plane surfaces will be cut by straight lines On certain conditions cylindrical and spherical surfaces may be cut Surfaces created by the GENERATE command using a cylindrical or spherical coordinate system which involves that the cylindrical spherical coordinate system will be assigned to the surface Prefem SESAM 3 26 01 JUN 2003 Program version 7 1 Surfaces to which a cylindrical spherical coordinate system has been assigned by the SET MESH COORDINATE SYSTEM command Surfaces projected onto a cylindrical or spherical shape The new surfaces resulting from the cutting will inherit the assignment to coordinate system alternatively the projection onto a shape from the original surfaces Note Surfaces projected onto shapes of type cone and interpolation will get straight cut lines Note Any non plane surface not satisfying the conditions above will get straight cut lines 3 3 5 Joining Geometry The JOIN command allows joining bodies Note Surfaces cannot be joined You cannot revert the cutting of a surface by joining the two halves 3 3 6 Rounding off Corners and Cutting Holes The DEFINE ROUNDED CORNER command rounds off corners as illustrated in Figure 3 22 Alterna tively to deleting the corner as shown in the figure the corner complement the whole surface but the cor ner may be deleted and none of the two surfaces may be
54. PRISM command The top and bottom surfaces must be comprised of the same number of lines curves Ifthe top and bottom surfaces are defined Starting in not prismatically corresponding points and or n opposite directions their surface normals points in opposite directions then this can be remedied by referring to start points and second points of both surfaces the start and sec ond points overrule the surface definitions In this way twisted prisms are avoided See Figure 5 26 for an illustration of this The points can be omitted if the definition of the top and bottom surfaces does cor respond PARAMETERS name User given name of the body top Name of the surface defining the top of the body bottom Name of the surface defining the bottom of the body start top Start point of the top surface corresponding to a start point of the bottom surface 2nd top Second point of the top surface which together with the start point defines the ro tational direction of the top surface SESAM Program version 7 1 start bot 2nd bot nelm Prefem 01 JUN 2003 5 77 Start point of the bottom surface corresponding to a start point of the top surface Second point of the bottom surface which together with the start point defines the rotational direction of the bottom surface Number of elements to be created along the automatically generated straight lines between the top and bottom surfaces See also the commands SET
55. Prefem Program version 7 1 01 JUN 2003 5 39 grav lc A previously defined load case containing the acceleration of gravity used in the computation of masses select geometry Points or lines for which loads shall be converted See Section 5 1 on how to per form a selection Prefem SESAM 5 40 01 JUN 2003 Program version 7 1 CHECK CLUSTERED NODES CLUSTERED POINTS CHECK ELEMENT SHAPE MESH TOPOLOGY NON REGULAR NODES PURPOSE The command checks the mesh The command also checks whether there are geometry points positioned closely together PARAMETERS CLUSTERED NODES Check whether nodes are positioned closely together and list such nodes CLUSTERED POINTS Check whether geometry points are positioned closely together and store such points in a named set ELEMENT SHAPE Check the shape of 2 D and 3 D elements MESH TOPOLOGY Check whether it is possible to create an element mesh with the given data consistency of data NON REGULAR NODES Identify surfaces with potential for mesh improvements by searching for so called non regular nodes SESAM Prefem Program version 7 1 01 JUN 2003 5 41 CHECK CLUSTERED NODES CLUSTERED NODES select geometry tolerance PURPOSE The command detects pairs of nodes positioned closely together and prints these pairs in the message win dow Clustered nodes may be caused by unintentionally coincident geometry In such case delete th
56. Prefem in which case there will exist a Prefem database causing the Database status to come up as Old Note On the other hand if your Command input file shall be added to an existing model then leave Database status as Old In this way you may repeatedly add Command input files to build up your complete model You may for instance first read a file containing definition of your pre ferred beam cross section types leave Prefem and then read the modelling input referring to these cross section types Note You may also read a Command input file from inside Prefem by using the SET COMMAND INPUT FILE command followed by the command see these 7 SESAM MANAGER 4 1 04 Project Prefem tutorial Superelement 1 Result l PEE ESE B AES General Modelling Program used PREFEM Database status New Input mode Graphics z Command input file Fie name z Model input jnl M Run interactively after command input file processing M White superelement on exit Optimise superelement Figure 4 1 Manager and the General Modelling window with Command input file specification SESAM Prefem Program version 7 1 01 JUN 2003 4 3 4 1 3 Starting Prefem as an Individual Program on Unix Alternatively to starting Prefem from Manager it may on Unix be started as an individual program Provided SESAM is properly installed on your computer Prefem is started by the command prefem in lower case The program responds by presenting it
57. RADIUS VARYING The function may be restricted to only having a value between two points 1 e zero value outside VALUE BETWEEN The validity of the function may be restricted to only elements between two points i e undefined not the same as zero outside ONLY BETWEEN In addition the following mathematical functions are available SIN COSIN ABS SIGN EXP LN DIM SORT MAX MIN The constant n is entered by the parameter Prefem SESAM 3 56 01 JUN 2003 Program version 7 1 PI Parentheses may be used for building up expressions remember that these are commands in themselves and must be separated from other commands and data by blanks E it E The basic and mathematical functions above have parameters Rather than giving numeric values for these parameters another function may be given Furthermore arithmetric operators may be used to add subtract multiply etc functions In this way functions of practically unlimited complexity may be specified The arithmetric operators are add e subtract multiply divide exponent Normal operator precedence is applied i e is calculated first thereafter and while and are calcu lated last Example 3 5 through Example 3 8 show examples of varying value input for loads Example 3 6 shows how a sinus function is defined by the construction SIN LINEAR 2POINTS VARYING pointl1 valuel point2 value2
58. Sandwich Elements Sandwich elements are multilayered shell elements comprised of normally three but in principal any number of layers through the shell thickness Sandwich elements are defined in the same way as other shell ele ments Observe however that the number of layers and the thickness of each layer in percentage of total shell thickness defined by the PROPERTY THICKNESS command are defined within the PROPERTY MATERIAL command as follows PROPERTY MATERIAL material name ANISOTROPIC 3D SHELL ELEMENT q1 q2 q3 rho nlay Here nlay is the number of layers q1 q2 q3 and rho are explained in the command description in Chapter 5 Layered Elements Layered elements are typically used for modelling stiffened plates This type of element allows the stiffeners to be modelled as an integral part the plate i e a layered element spans several stiffeners of the plate See SESAM Prefem Program version 7 1 01 JUN 2003 3 65 Figure 3 56 This feature provides a solution to the dilemma of choosing between modelling all stiffeners as beams which involves small plate elements in between all stiffeners which in turn easily yields an exces sively large model and lumping stiffeners by modelling only some of them and adding their stiffnesses which will produce incorrect local results plate layer stiffener layer for web stiffener layer for flange stiffened plate seen from underneath layered element with one plate and two stiffener l
59. The requirements are e e The model must be defined in the x y plane and with positive x values only see Figure 3 58 Axi symmetric elements must have anti clockwise internal node numbering as shown in Figure 3 58 This is achieved by defining the surfaces by referring to the bordering lines in anti clockwise direction SESAM Prefem Program version 7 1 01 JUN 2003 3 67 The radius x axis in the model must be zero at the axis of symmetry for all superelements This implies that when positioning a superelement in Presel it is only allowed to translate it in y direction and to mirror it about the x z plane Only concentrated loads in points are allowed Direction for surface definition An element with local node numbering 3 D structure 2 D model Figure 3 58 Requirements to axi symmetric FE model 3 11 Transformations and Coordinate Systems 3 11 1 Transformations Transformations are defined by either the DEFINE TRANSFORMATION command or the PROPERTY TRANSFORMATION command The difference between these two commands is first of all that the former is the more powerful one in addition to a pure rotational type of transformation a translational scaling and even mirroring type of transformation may be defined Secondly their methods for defining a rotational transformation differ Apart from this the use of the transformations is the same The user may find that solely using the DEFINE TRANSFORMATION command both o
60. X emulator is used as a terminal towards a Unix server In such cases reduce the WINDOW SIZE argument value SESAM Prefem Program version 7 1 01 JUN 2003 4 9 4 2 Program Requirements 4 2 1 Execution Time The execution time required is negligible for most commands A few commands however will require some CPU and should be used with care on low capacity computers These are the MESH ALL and any command involving extensive selection of geometry by use of wild card names Note For large models the DISPLAY and MESH commands may require some time During processing of these commands you may use Shift Esc to abort them This will have no effect on the program execution apart from incomplete execution of the command in question and you may continue modelling This is available on PC only a similar feature is not available on other operating systems 4 2 2 Storage Space The initial size of the data base prior to any modelling is about 2 MB 10 20 MB will be sufficient for most models Big models may require 100 MB and more 4 3 Program Limitations Graphics Devices The graphical user interface is implemented for OSF Motif X Window and MS Windows Under OSF Motif X Window window stretching is disallowed use the WINDOW SIZE command line argument instead Memory Prefem allocates memory buffers for access to data of the data base file When using the graphical user interface Prefem will allocate memory for the display File
61. a cylinder Define a shape being a cone Define a shape being an interpolation between two unconnect ed curves User given name of the shape Points used for defining the shapes Radii used for defining the shapes Names of lines arcs and or splines of the first curve Conclude entering names by END Names of lines arcs and or splines of the second curve Con clude entering names by END SESAM Prefem Program version 7 1 01 JUN 2003 5 85 DEFINE SPLINE next point SPLINE name start point nelm END PURPOSE The command defines the geometric entity spline This is a curve in the form of a general B spline of the 4th order degree 3 interpolated between the points There is no limit to the number of points defining the spline PARAMETERS name User given name of the spline start point Name of the point defining the start point of the spline next point Name of the next point of the spline When the last point has been entered conclude by entering END nelm Number of elements to be created along the spline See also the commands SET NUMBEROF ELEMENTS and SET MAX ELEMENT LENGTH The number of elements is independent of the number of points defining the spline This implies that nodes will not necessarily be created in the points along the spline NOTES The direction of the spline going from start point to end point has consequence for the local coordinate sys tem of beam el
62. access buffer The memory is allocated when Prefem is started and the amount is fixed until exiting the program The amount of memory allocated can be changed by editing the configuration password file To change the amount insert or modify the line MSIZE PREFEM BUFFER buffer bytes where buffer bytes represents the amount of memory Prefem will allocate in bytes The default value is 2457600 2 4576 millions representing 150 buffers of 16384 bytes each The buffer should be changed if for example there is not enough memory to use the graphical user interface Note however that in creasing the memory for buffers will not improve performance much Memory for graphical user interface The graphic mode window will use memory and allocate it when needed Large displays will need more memory than small displays Prefem SESAM 4 10 01 JUN 2003 Program version 7 1 Typing While typing a command using the keyboard you cannot click commands in menus or select geometry by clicking or use the mouse in any other way until the Return key has been hit or until the typed text has been deleted by backspace SESAM Prefem Program version 7 1 01 JUN 2003 5 1 5 COMMAND DESCRIPTION The hierarchical structure of the commands and numerical data is documented in this chapter by use of tables How to interpret these tables is explained below Examples are used to illustrate how the command structure may diverge into multiple choices and converg
63. after highlighting all adjoining surfaces the adjoining bodies will be highlighted one after another Note that you cannot loop through the geometrical entities more than once i e after highlighting the last body clicking the RMB will no longer have any effect The availability of graphical selection is subject to that geometry selection has been switched on by the Direct access buttons Point Line Surface and Body By default they are all switched on depressed See information on these buttons in Section 3 1 Note that if the Direct access button Info is depressed then geometry cannot be selected by clicking See information on the Info button in Section 3 1 3 9 2 Line Mode Command Selection of Geometry Geometry can be selected by line mode commands as follows e Giving the geometry name directly Giving several geometry names within parentheses remember to insert a space on both sides of the parentheses the parentheses are commands in themselves geo namel geo name2 geo name3 Giving the commands ALL BODIES INCLUDED ALL SURFACES INCLUDED ALL LINES INCLUDED ALL POINTS INCLUDED Giving wild card type geometry names see Section 3 9 3 Giving name of a defined set see Section 3 9 4 Using the command GEOMETRY OF ELEMENT and giving an element number thereby selecting the geometry to which the element belongs the geometry name is logged on the command log file Excluding geometry names from geometry already sel
64. alternatives that follow correspond to the PROPERTY LOCAL COORDINATE BEAM command see this The local zx plane is used for determining the local coordinate system The command alternatives that follow correspond to the PROPERTY LOCAL COORDINATE BEAM command see this Set material name that will be assigned to subsequently created geometry Note The default set by this command is overruled by explicit assignment using the CONNECT MATE RIAL command A previously defined material name Set maximum element length that will be assigned to subse quently created lines Note The default set by this command is overruled by explicit assignment using either the SET NUM BEROF ELEMENTS command or the SET MAX ELEMENT LENGTH command Element length Set number of elements that will be assigned to subsequently created lines The default is 4 Note The default set by this command is overruled by explicit assignment using either the SET NUM BEROF ELEMENTS command or the SET MAX ELEMENT LENGTH command Number of elements Set section name that will be assigned to subsequently created lines Note The default set by this command is overruled by explicit assignment using the CONNECT SEC TION command A previously defined section name SESAM Prefem Program version 7 1 01 JUN 2003 5 219 THICKNESS Set thickness that will be assigned to subsequently created sur faces Note The default set by this command is overruled by
65. and conclude the selection of the three lines with left and right parentheses Click once more the Shortcut command Display Mesh to display the mesh and see that the meshes in the three areas have improved Use the PROPERTY BOUNDARY CONDITION command to define boundary conditions First click the Direct access button Draw Geo to display the geometry and allow you to select geom etry Thereafter select the lines curves remember parentheses identified by an A in Figure 3 4 and give the boundary conditions FIX FREE FREE FREE FIX FIX for the six degrees of freedom translations in X Y and Z and rotations about the same Then select the vertical line of the bulkhead midship identified by a B in Figure 3 4 and give the boundary conditions as specified Select the two end points of the centre line girder C in Figure 3 4 and give the appropriate boundary conditions Finally select the two points in the deck centre line D in Figure 3 4 and give the appropriate bound ary conditions Note that the boundary conditions given for the points will replace those previously given for the lines the points are encompassed by the selected lines It is therefore necessary to give boundary conditions for the points at the end Use the PROPERTY LOAD command to define loads see Figure 3 5 Load case number 1 is a COMPONENT PRESSURE meaning that three components of the pressure shall be given X Y and
66. are described by their thicknesses materials and possible eccentricities The stiffeners are described by their cross sections materials positions spacing eccentricities and directions PARAMETERS layered name User given name of the layered element This name will be as signed to the appropriate surfaces by the CONNECT com mand SESAM Program version 7 1 PLATE STIFFENER THICKNESS thickness MATERIAL material name SHEAR FACTOR sh fact SECTION section name angle SPACING INFINITE PLATE spacing ECCENTRICITY ECCENTRIC CALCULATED NEGATIVE Z OFFSET LOCAL COORDINATE OFFSET dx dy dz NOT ECCENTRIC Prefem 01 JUN 2003 5 65 A plate layer is to be defined A stiffener layer is to be defined Thickness of a plate layer is to be specified The constant thickness of the plate A function cannot be used Material of the plate stiffener is to be specified A previously defined material name The material must be iso tropic and elastic A shear factor is to be specified for the plate stiffener layer The shear factor Cross section is to be specified for the stiffeners A previously defined section name The section must be of the bar type The angle between the stiffener direction and the local x axis of the plate element The local x axis is determined by the PROP ERTY LOCAL COORDINATE SURFACE command The spacing between the stiffeners is to be specified Implies that the stiffen
67. are given in terms of X Y and Z components Having cho sen a cylindrical coordinate system only the component is given It follows that copying extrusion can only be done in the circumferential 6 direction SESAM Program version 7 1 Prefem 5 100 01 JUN 2003 The final input to the EXTRUDE command is to choose between the following options Copy geometry to copy but do not extrude anything The geometry to extrude becomes irrelevant in this case Copy geometry to copy and extrude points belonging to geometry to extrude to lines Even if the geometry to extrude includes lines and surfaces only points will be extruded Copy geometry to copy and extrude points and lines belonging to geometry to extrude to lines and surfaces respectively Copy geometry to copy and extrude points lines and surfaces belonging to geometry to extrude to lines surfaces and bodies respectively PARAMETERS geometry to copy copy prefix geometry to extrude extrude prefix GLOBAL CYLINDRICAL orig x orig y orig z Zaxi X zaxi y zaxi z raxi x raxi y raxi z n copy extrude REPEAT n times dx dy dz dphi COPY ONLY POINT TO LINE LINE TO SURFACE Select geometry to copy See Section 5 1 on how to perform a selection Bodies cannot be selected Prefix for geometry names of the copies This prefix precedes default names Select geometry to extrude See Section 5 1 on how to perform a selection Bodies can
68. character s Note Graphical selection of geometry does not work if the Info button is depressed You will then instead get information on the geometry See the explanation of the Info button above 3 2 Tutorial in Midship Section Modelling A tutorial based on using Prefem in graphic mode is presented here Start Manager and open a new project Then give Model General Prefem or click the appropriate tool but ton and the General Modelling Prefem start up window appears see Figure 3 3 This window offers the following choices The Database status will come up as New when Prefem is started the first time for a project If you leave Prefem the Prefem database will automatically be saved and re enter to continue modelling the Data base status will come up as Old as Manager will detect the existing database Changing Old to New in such a case involves deleting the existing database and creating a new and empty one i e starting afresh The Input mode box should always be Graphic Section 4 1 2 explains the use of the Command input file box In this case let it be None By default the Write superelement on exit box will be checked This involves that the Input Interface File containing the model the file transferred to the analysis program will be written when leaving Prefem by the EXIT command If you foresee that you will not complete modelling in the current session you may uncheck this box But in the final session you ne
69. command See Figure 3 69 Note The concept of inside and outside of bodies has as for the surfaces relevance for the applica tion of loads only Note When there are shell elements on the surface of a body with solid elements a type of modelling which may be employed for a sandwich type structure and when the use of sandwich and lay ered elements for some reason is not desired then the definition of inside outside will be deter mined by the surface and not by the body This may involve that the direction of a NORMAL PRESSURE load will change depending on whether a layer of shell elements are found on the surface of the solid elements or not lo surface S The table below shows the effect of defining a positive body NORMAL PRESSURE and a negative NORMAL PRESSURE Y for surface S which is one of the enclosing surfaces of a body X positive NORMAL PRESSURE ae outside Positive pressure points inside from outside towards inside outside negative NORMAL PRESSURE UM outside Negative pressure points inside from inside towards outside outside Figure 3 69 Pressure loads applied to body Prefem SESAM 3 78 01 JUN 2003 Program version 7 1 SESAM Prefem Program version 7 1 01 JUN 2003 4 1 4 EXECUTION OF PREFEM This section provides information on How to start Prefem How to read a Command input file into Prefem How to execute Prefem outside Manager Unix only Line mode input syntax Files used Cr
70. command END is generally used to end repetitive entering of data Using double dot rather than END to terminate a command will depending on at which level in the command it is given save or discard the data entered Generally if the data entered up to the double dot is complete and self contained the double dot will save the data If in doubt it is always safest to leave a command by entering the required number of END commands 5 1 Selecting Geometry Selecting geometric entities is relevant in many commands e g for defining properties The following ways of selecting geometry are available Graphical selection see Section 3 9 1 Line mode command selection see Section 3 9 2 and below Wild card selection see Section 3 9 3 Selection through set see Section 3 9 4 Below is a complete list of line mode command alternatives for selecting geometry In cases where selecting only a certain type of geometry is relevant e g only surfaces when giving shell plate thickness then only the relevant type of geometry is available for selection In many cases selecting certain geometry will involve selecting also the lower level geometric entities contained in the selected geometry e g selecting a surface when defining boundary conditions involve selecting the lines and points contained in the surface as well Note Whenever geometry is to be selected you may employ any combination of the line mode com mands explained below and graph
71. consistent with a Z axis pointing vertically upwards SESAM Prefem Program version 7 1 01 JUN 2003 5 153 PROPERTY LOAD load case HY DRO PRESSURE INSIDE SURFACE INSIDE MIDDLE SURFACE OUTSIDE SURFACE INSIDE LAYER OUTSIDE MIDDLE LAYER layer OUTSIDE LAYER HYDRO PRESSURE select surfaces PURPOSE The command identifies surfaces that are to be subjected to hydrostatic and hydrodynamic pressures com puted in a subsequent hydrodynamic analysis using Wadam In which direction the pressures act i e on which sides of the surfaces the fluid is is decided by determining the wet surfaces by referring to the inside or outside of the surfaces For shell elements the HYDRO PRESSURE is applied to the inside middle or outside surface of the ele ments For the concept of inside and outside of surfaces see Section 3 12 3 The inside middle and outside layer is similar but is relevant for layered elements To understand the reason for specifying first inside outside and then inside middle outside surface consider this The former specification determines the direction of the pressure computed by Wadam which is the wet and which is the dry side whereas the latter specification determines where the pressure is going to act Obviously in normal cases INSIDE should be followed by INSIDE SURFACE and OUTSIDE should be followed by OUTSIDE SURFACE For solid elements the inside middle and outside s
72. depending on type of element S m u 3 5 3 o A p gt 5 e o B 5 5 n Type of element 5 rz 2 2 ole 2 o D o 8 a D A Ss o e Q o 6 Me o a c Es zc Oo ss o g 5 pos gt e Sg GAVES EAEz Slol BIS ERIS 9S 8l8siSS l8 amp 2 amp Truss X Ss o s Beam X x X X X n E Curved beam x x 2 x X Constant strain triangle 1 2 x 3 un o S Linear quadrilateral 1 2 x 3 Eel 5 Isoparametric linear strain triangle 1 2 x 3 Isoparametric quadratic strain quadrilateral 1 2 x 3 Axi symmetric elements corresponding to membranes 4 4 Triangular flat thin shell x x 2 x x x x x Quadrilateral flat thin shell x x 2 x x x x x Subparametric curved triangular thin thick shell x x 2 x x x x x 4 Subparametric curved quadrilateral thin thick shell x x 2 x x x x x e Curved triangular sandwich element based on SCTS x x 2 x x x x Curved quadrilateral sandwich element based on x x 2 x x x x SCQS Curved triangular layered shell based on SCTS x x 2 x x x x x Curved quadrilateral layered shell based on SCQS x x 2 x x x x x SESAM Prefem Program version 7 1 01 JUN 2003 2 11 Table 2 3 Allowable loads for a Sestra analysis depending on type of element iss E D D 3 8 B 5 un 4 o S o a Z 5 amp 8 Type of ele
73. existing geometry thereby modifying it Rounding off corners command DEFINE ROUNDED CORNER and cutting a sector or hole in a cor ner command DEFINE SECTOR CORNER thereby modifying existing geometry Importing geometry from a DXF file a drawing exchange format supported by many CAD systems All geometric entities have unique names The names have a maximum length of 8 characters and start with any letter names starting with X are reserved for program generated names The names are given by the user when defining the geometry or optionally automatically assigned by the program All reference to existing geometry is made by either referring to these names or by selecting geometry by graphical means i the structure the geometry model with points and lines and their names Figure 3 10 The geometry model of a structure 3 3 1 Defining Geometry Defining Points A point is the simplest geometrical entity It is described by coordinates in the cartesian coordinate system of the model and defined by the DEFINE POINT command The coordinates are either given directly given relative to other points calculated as an interpolation between two points or calculated as an intersection between three shapes Even though a model always will have a cartesian coordinate system cylindrical and spherical coordinate systems may be used for defining the points A few examples of how to define points are given below The two commands below first define
74. file This may be changed by the SET PLOT FILE command the SET GRAPHIC PLOT FILE command has the same effect The default format is SESAM NEUTRAL This may be changed to PostScript CGM and other formats by the SET PLOT FORMAT command The SET PLOT COLOUR command is used to store colour information on the plot file When plotting colours you may want to adjust certain light colours to make them visible on white paper Use the SET GRAPHICS COLOUR command for this purpose If plot properties are to be set by the SET PLOT command these settings must be done prior to giving the PLOT command The paper format A1 A5 is only relevant for the SESAM NEUTRAL plot format For other formats this entry is dummy If 2 or 4 viewports are used then only the isometric view is plotted SESAM Program version 7 1 01 JUN 2003 PRINT Prefem ALL STATUS BODY SURFACE select geometry GEOMETRY LINE POINT PROPERTY set name SET ALL SHAPE select shapes SPRING DAMPER select spring dampers BASIC ELEMENT ELEMENT select elements ECCENTRICITY LOCAL COORDINATE S YSTEM PRINT COORDINATES BOUNDARY CONDITIONS NODE select nodes LINEAR DEPENDENCY INITIAL CONDITIONS MASS load case ALL LOADTYPES LOAD select geometry ALL load type LAYERED name MATERIAL ALL SECTION trnam DECODED TRANSFORMATION ALL UNDECODED CONNE
75. for the element thicknesses ABOVE Only the thicknesses above the subsequently given value are presented SPECIFIED RANGES The thicknesses in between given values are coloured Several values similar to contour lines or iso curves may be entered The END alternative concludes the list of values This option is convenient when variable thickness has been specified value Thickness values determining the presentation tol Tolerance value determining whether two thicknesses are the same or not MATERIAL Colour 2 D and 3 D elements according to the material name assigned connected OFF Switch off colour identification of either thickness or material NOTES In graphic input mode there are Shortcut commands see Section 3 1 available for presenting the thick nesses and material names using the filled element option SESAM Prefem Program version 7 1 01 JUN 2003 5 111 LABEL NODE SYMBOL ON OFF FIXED NODES NODE SYMBOL FREE NODES LINEAR DEPENDENT NODES PRESCRIBED NODES OFF SUPER NODES ON PURPOSE The command switches on and off labels symbols for nodes according to their boundary condition The node symbols are shown in Figure 5 36 The symbols for fixed degrees of freedom line and double arrow with crossbars are not switched on by this command but rather the LABEL BOUNDARY CONDITION SYMBOL command In addition to switching on and off the node symbols individually
76. format for printing temperature loads For use when nodal temperature values are printed Only the temperature applied to the first element connected to the node is printed If requested the program will give a message if dif ferent temperatures have been applied to the node see the DIF FERENCE CHECK option Only nodes connected to elements where temperature loads have been applied are print ed Only solid elements are printed and checked This com mand translates the internal representation of temperature loads as element loads to nodal loads As temperature loads in mid side nodes are not taken into ac count in the analysis printing of these may be switched off Prefem SESAM 5 256 01 JUN 2003 Program version 7 1 DIFFERENCE CHECK This option is relevant only in combination with the NODAL FROM SOLID switched ON A question mark is printed af ter the node number if the node has been given different tem peratures in different elements connected to the node SESAM Prefem Program version 7 1 01 JUN 2003 5 257 SET PROJECTION PROJECTION surface name shape name PURPOSE The command determines that nodes created at the interior of a surface shall be projected onto a shape This projection is performed during the meshing operation See Section 3 4 5 for information on mesh for sur faces PARAMETERS surface name The name of a surface shape name The name of a previously defined shape see th
77. freedom F fixed P prescribed L linearly dependent S super The column LIN DEPENDENCY BY POINT contains information on linear dependencies POINT MASS LIN DEPENDENCY NAME X Y Z BOUND BY POINT P1 FFF F P2 FFF F P3 PPP P4 350 000000 350 000000 350 000000 SE 0 000000 0 000000 0 000000 P5 350 000000 350 000000 350 000000 LLLLLL T P P6 0 000000 0 000000 0 000000 P4 P6 SSS Pic Print of geometry information for lines The table tells by which points the lines arcs and curves are defined If a line curve is defined as the inter section between shapes then the shape names are given as well The number of elements that the lines arcs and curves will be divided into is also given column PARTS LINE START END CENTER NEAR PO SHAPE1 SHAPE2 NAME TYPE PARTS POINT POINT POINT POINT POINT POINT L1 LINE 9 P4 P2 L2 LINE 4 P2 P3 L3 LINE 3 P3 P4 L4 LINE 3 P4 P5 L5 LINE 2 P5 P6 ARC1 ARC 4 P6 Pl PCENTRE SESAM Program version 7 1 Prefem 01 JUN 2003 5 121 Print of property information for lines The table contains property information for lines type of element material boundary condition code see Print of point properties above type of cross section existence of load an x in column LOAD informs that a load has been defined for the line and eccentricity CALC means that the eccentricity is calculated by the program 1 e the PROPERTY ECCENTRICITY BEAM CALCULATED command has b
78. ing an old version of the meshing algorithm within the latest version of Prefem This may be relevant when a command in put file created for a previous Prefem version is read into the latest version The version number a number 1 2 The Status List will contain information on the meshing version number The meshing version of the current Prefem version distorted mesh NOTES line geometry regular rectangular mesh Figure 5 56 Mesh for an L shaped surface The SET MESH CORNER and SET NOT MESH CORNER commands have the same effect as the corre sponding SET MESH CORNER TYPE commands The mesh corners can be visualised by the LABEL MESH CORNER command The SET MESH PARAMETERS MAX MESH CORNER ANGLE command allows overruling the setting of mesh corner See this SESAM Prefem Program version 7 1 01 JUN 2003 5 243 SET MESH CORNER NOT MESH CORNER MESH CORNER point name surface name NOT MESH CORNER END PURPOSE The command sets mesh corners and not mesh corners for surfaces The user is however recommended to use the SET MESH CORNER TYPE command as this includes all alternative corner types See Section 3 4 4 for general information as well as examples of corner types PARAMETERS MESH CORNER Set mesh corners NOT MESH CORNER Set not mesh corners surface name Name of a single surface Wild card name is not allowed point name Name of a point on the border o
79. is established Solid elements are created for bodies if relevant It follows from the above that making a surface mesh e g shell elements with and without line elements e g stiffener beams is governed by whether beam elements have been requested in addition to shell ele ments Geometry model FE model the mesh line curve elements I p nodes Figure 3 29 The MESH command automatically creates the FE mesh based on a geometry model Prefem SESAM 3 36 01 JUN 2003 Program version 7 1 3 4 1 Controlling the Mesh Creation The following data must be defined to enable creation of the FE model Data determining the element discretisation The number of elements is determined when defining lines and curves This setting is changed by the commands SET NUMBEROF ELEMENTS and SET MAX ELEMENT LENGTH The spacing of elements for lines and curves is by default even i e all elements element edges are equal in length The command SET ELEMENT LENGTH RATIO is used to set the ratio between the element lengths see Figure 3 30 Desired type s of element is set by the SET ELEMENT TYPE command See Section 2 5 for informa tion on types of elements available element edges have by default equal lengths user defined element spacing Figure3 30 Example of default and user defined element spacing A maximum of four mesh corners are allowed for a surface see Figure 3 31 There is one exception when there is only one elem
80. layered shell based on g 6 SCQS d Contact element 4 nodes per face CONTACT 4 4NODES CTLQ INTER4 8 3 CONTACT 8 8NODES CTCQ Contact element 8 nodes per face 16 3 E Contact element 9 nodes per face CONTACT 9 9NODES CTMQ INTER9 18 3 SOLID 6NODES TPRI Triangular prism 6 3 SOLID 8NODES LHEX Linear hexahedron 8 3 SOLID 15NODES IPRI Isoparametric triangular prism 15 3 SOLID 20NODES IHEX Isoparametric hexahedron 20 3 2 to 27 node full integration brick SOLID 21 TO 27 NODES GHEX C3D27 21 27 3 SPRING TO GROUND GSPR Spring to ground 1 1 6 SPRING AXIAL AXIS Axial spring 2 6 DAMPER TO GROUND GDAM Damper to ground 1 1 6 DAMPER AXIAL AXDA Axial damper 2 6 MASS ELEM ONE NODE GMAS General one node mass element 1 1 6 Elements only available in Advance SESAM Prefem Program version 7 1 01 JUN 2003 2 7 TRUSS BEAM 3NODES ee BEAM 2NODES MEMBRANE 8NODES SHELL 8NODES AXIS YMMETRIC 8NODES SANDWICH 8NODES LAYERED 8NODES MEMBRANE 4NODES SHELL 4NODES SHELL DRILLING 4NODES AXISYMMETRIC 4NODES MEMBRANE 6NODES MEMBRANE 3NODES SHELL 6NODES SHELL 3NODES AXIS YMMETRIC 6NODES SHELL DRILLING 3NODES SANDWICH 6NODES AXISYMMETRIC 3NODES LAYERED 6NODES also SHELL 9NODES SOLID 6NODES SOLID I3NODES p SOLID 8NODES SOLID 20NODES also MES SOLID 21 TO 27 NODES SPRING TO GROUND NIL SPRING AXIAL CONTACT 8 8 NODES DAMPER TO GROUND DAMPER AXIAL also CONTACT 4 4 NODES CONTACT 9 9 NODES
81. load intensities found by evaluating the specified function For very thick shell structures this may have a significance layer A The table below shows how pressure loads defined for the outside of a middle layer s curved surface depend on which surface is the outside one The loads layer B x are COMPONENT PRESSURE a positive NORMAL PRESSURE and a negative NORMAL PRESSURE Y Ly l The middle layer has the same position as the geometry surface layer A 1s outside layer B is outside load sum will be high load sum will be low positive X component of COMPONENT PRESSURE The direction of the load does not change when outside layer changes from A to B positive NORMAL PRESSURE The direction of the load changes when layer B is made outside because positive pressure points from outside towards inside negative NORMAL PRESSURE The direction of the load changes when layer B is made outside because negative pressure points from inside towards outside Figure 3 68 Pressure loads applied to surface SESAM Prefem Program version 7 1 01 JUN 2003 3 77 Inside Outside of Bodies When defining a pressure load for a body the surfaces subjected to the pressure are referred to in the com mand The inside of a body is automatically determined by the program as the side of the surface where there are solid elements This cannot be changed by the SET INSIDE OUTSIDE command or by any other
82. load shall apply the MIDDLE SURFACE Give END to leave definition of load case 2 Display the mesh Shortcut command Display Mesh and then click the Shortcut command Display Add Load and give load case 2 Hit Return once more and the load case will be displayed Notice that for the two curved surfaces in the bilge area the pressure points in the wrong direction This is caused by that the element normal points in the wrong direction for these surfaces With the mesh dis played you may use LABEL ELEMENT NORMAL ON to see the element normals The direction of the element normals is a function of the way the surfaces were defined To change the direction of the element normals and therefore also the pressure do as follows Use the DELETE MESH ALL command to delete the current mesh Click the Shortcut command Geometry or the Direct access button Draw Geo Use the CHANGE ROTATION OF SURFACE command and select the two surfaces in question Use the MESH ALL command to re create the mesh Display the mesh once more and add display of load case 2 and see that the pressure now points in the proper direction The model should now be complete Use the SET GRAPHICS PRESENTATION BEAM ELEMENT SEC TION AS SOLID command to display the girders with their sections shown and in their eccentric position Try out the various Shortcut commands for example Present Col Thi and Present Col Mat and Direct Access
83. model in the following figures consists of two surfaces while the FE model consists of eight 4 node shell elements and six 2 node beam elements Note that the commands given in the figures are not nec essarily complete in that intermediate commands like END or may have been omitted Some of the com mands are also abbreviated The geometry with point line and surface names Only points DISPLAY GEOMETRY DISPLAY POINT ALL POINTS INCLUDED ABEL POINT NAMES ON ABEL LINE NAMES ON LABEL SURFACE NAMES ON Figure 3 60 Display features 1 SESAM Prefem Program version 7 1 01 JUN 2003 3 71 The geometry with mesh corners and point names Only selected surface and line and surface names LABEL MESH CORNER ON DISPLAY SURFACE AU111 Figure 3 61 Display features 2 The geometry with surface names with mesh Only mesh with hidden lines removed and outline added beams drawn between nodes with thick of eccentric beam sections I and box sections lines SET GRAPHICS HIDDEN ON ADD DISPLAY MESH SET GRAPHICS PRESENT BEAM ELEMENT OUTLINE SECTION DISPLAY MESH Figure 3 62 Display features 3 Prefem SESAM 3 72 01 JUN 2003 Program version 7 1 Thickness 8 0E 02 I
84. model to a cylindrical r z sys tem The cartesian X axis is used as the cylinder axis The cartesian Y axis defines the o 0 plane The cartesian Y axis is used as the cylinder axis The cartesian Z axis defines the o 0 plane The cartesian Z axis is used as the cylinder axis The cartesian X axis defines the 0 plane Select FILE or SCREEN for output from subsequent PRINT commands A PRINT ALL command will always send its print to FILE Default for all other PRINT commands is SCREEN Set file prefix and name for the print file Default is the same as for the model file The file extension is LIS Set format of print of loads As the same node or element may be given the same type of load for the same load case more than once the resulting load is an accumulation of all these loads there is a possibility for accumulating these loads in the print tables This accumulation may be switched ON and OFF Default is off This is only rele vant for printing of loads for elements and nodes SET PRINT EXTENT MESH Select printing of loads to be in the form of tables over loads for geometric entities GEOMETRY or tables over loads for ele ments and nodes MESH or for both geometric entities and el ements nodes ALL GEOMETRY is the default choice Set number of digits for the node numbers to 4 DIGITS or 5 DIGITS 4 digits makes the print tables easier to read and is the default choice Only use 5 digits when necessary Set
85. n times PURPOSE The command defines geometry by generating a regular geometry consisting of points lines surfaces and bodies A regular geometry is in a cartesian system a geometry only consisting of surfaces shaped as par allelograms The command is based on first defining a topological I J K space and then by use of vectors mapping this space into a geometrical coordinate system SESAM Program version 7 1 Prefem 01 JUN 2003 5 103 The GENERATE command is somewhat complex On the other hand it is capable of creating large and complex geometries of rectangular cylindrical and spherical shape with a very limited amount of input It may therefore be worthwhile to learn how to use it Section 3 3 7 contains an explanation of the command as well as illustrative examples Figure 5 35 Example of a topological space PARAMETERS BY NAME This optional command enables adding higher level geometry onto lower level ge ometry without having to repeat specification of coordinate system and geometry information If for example points have previously been generated then lines may be added The GENERATE BY NAME command will be equal to the original GENERATE command only replacing POINT by LINE and skipping specification of coordinate system starting point and vectors BODY Generate bodies surfaces lines and points SURFACE Generate surfaces lines and points LINE Generate lines and points POINT Genera
86. names Figure 5 57 Naming geometry after cutting If a geometry name does not adhere to the naming system i e the mask name does not fit then a default name POi for points Lli for lines etc will be used for the new geometry PARAMETERS CUT Determine geometry names in connection with CUT command DEFAULT By default all names are generated by incrementing the number i in the standard names POi for points Lli for lines SUi for surfaces and BOi for bodies MASK Use a mask type of naming mask The mask name Prefem 5 248 01 JUN 2003 SET NOT MESH CORNER surface name point name NOT MESH CORNER END PURPOSE The command sets not mesh corners See the SET MESH CORNER command for a full description SESAM Program version 7 1 SESAM Prefem Program version 7 1 01 JUN 2003 5 249 SET NUMBEROF ELEMENTS NUMBEROF ELEMENTS select lines nelm PURPOSE The command defines the number of elements for a line or a group of lines See Section 3 4 for more information PARAMETERS select lines Select lines See Section 5 1 on how to perform a selection nelm Number of elements for the selected lines NOTES See also the SET MAX ELEMENT LENGTH command Prefem 5 250 01 JUN 2003 SET OUTSIDE POINT point name COORDINATES x y z X Y OUTSIDE select surfaces corner point
87. non meshable surfac es meshable See explanation above select surfaces Surfaces that shall be made meshable See Section 5 1 on how to perform a selection ALL Mesh all geometric entities for which type of element has been defined Prefem SESAM 5 114 01 JUN 2003 Program version 7 1 PART Mesh only selected geometry or create all spring and damper elements select geometry Geometry to be meshed See Section 5 1 on how to perform a selection ALL SPRINGS DAMPERS INCLUDED Create all spring and damper elements SESAM Prefem Program version 7 1 01 JUN 2003 5 115 PLOT DISPLAYED GEOMETRY MESH BODY PLOT Pee select geometry textline 4 A3 LINE POINT ELEMENT select elements NODE select nodes LOAD load case load type Al A2 A4 AS PURPOSE The command generates a plot file which subsequently can be sent to a printer or imported in a word proc essor The drawing is plotted with the current viewing position Four lines of text each of maximum 24 characters are specified These are reproduced on the plot The date and time when the plot was generated will be given on the plot together with the scale PARAMETERS DISPLAYED Plot the current display GEOMETRY Plot the whole geometry MESH Plot the whole element mesh BODY Plot selected bodies SURFACE Plot selected surfaces LINE Plot selected lines POINT Plot selected points
88. number of elements or maximum element length for lines This involves automatic execution of the MESH ADJUST command Note that the there is a Shortcut command button which toggles this automatic mesh adjust ment Switch on off automatic naming mode This involves that rath er than prompting the user Prefem will automatically generate geometry names when geometry is defined The logging of the commands for defining geometry will include the automatical ly generated names SESAM Program version 7 1 COP Y ELEMENT TYPE ELEMENT TYPE LINE SURFACE BODY element type NONE EYE DIRECTION eyex eyey eyez LINEAR DEPENDENCY MODE FORCE TO SUPER NO FORCE TO SUPER LOCAL COORDINATE BEAM Prefem 01 JUN 2003 5 217 Switch on off whether type of element is going to be carried over when geometry is copied See the COPY command Set type of element that will be assigned to subsequently creat ed geometry Set default type of element for subsequently created lines Set default type of element for subsequently created surfaces Set default type of element for subsequently created bodies Choose desired type of element See Section 2 5 Any element type previously chosen for this geometry is an nulled Specify the default direction from origin to eye i e the de fault viewpoint See the SET GRAPHICS EYE DIRECTION command for further explanation This setting will overrule the setting when starting Prefem typically
89. of a previously defined shape Name of a previously defined shape Name of a previously defined shape Shift to a named cylindrical or spherical coordinate system or back to the cartesian coordinate system of the model GLO BAL Name of a previously defined coordinate system Use the cartesian coordinate system of the model SESAM Prefem Program version 7 1 01 JUN 2003 5 75 gt Current coordinates prior to shape intersection Current coordinates updated to intersection point Figure 5 25 Defining point by SHAPE INTERSECTION Prefem SESAM 5 76 01 JUN 2003 Program version 7 1 DEFINE PRISM 2nd top 2nd bot start bot PRISM name top start top bottom END nelm END END PURPOSE The command defines the geometric entity body and is a short version of the DEFINE BODY command Only the top and bottom surfaces must previously have been defined The DEFINE PRISM command will define Straight lines between corresponding points of the top and bottom surfaces All side surfaces of the body The body The command takes advantage of how bodies are by definition They are logically prisms enclosed by top and bottom surfaces and any number of quadrilateral side surfaces See the DEFINE BODY command for more information on requirements to a body and its mesh Compared with the DEFINE BODY command some requirements must be met in order to use the DEFINE
90. of the cartesian coordinate system see the command DE FINE TRANSFORMATION The load components refer to a previously defined cylindrical or spherical coordinate system see the command DEFINE COORDINATE SYSTEM No additional transformation of the cylindrical or spherical coordinate system is performed Name of a previously transformation Name of a previously defined coordinate system Load force and moment components Imaginary load force and moment components By entering data for these the load will implicitly become a complex load SESAM Prefem Program version 7 1 01 JUN 2003 5 151 Entering END rather than ifx ify imz implies that the load is real NOTES The point selected for the concentrated load need not be a part of the geometry model for which a FE mesh is created It may also be a loose point which is positioned within the general coordinate tolerance see the SET TOLERANCE COORDINATES command from a node of the FE model In such case the load is applied to this node There is a risk however that the node created by the automatic meshing does not hap pen to coincide with the point in which case the load is not applied to the model A new program version with an updated meshing algorithm may also position the nodes differently and the load will be lost Conse quently this feature should be used with care Prefem 5 152 SESAM 01 JUN 2003 Program version 7 1 PROPERTY LOAD load c
91. plane is thus generated easily and directly The command allows control over the storing of sets see the DEFINE SET command on the Input Inter face File By default all sets 1f any are defined with their full contents 1 e nodes and elements are stored on the Input Interface File PARAMETERS 2DIMENSIONAL 3DIMENSIONAL INCLUDE SET set name ALL NODES ELEMENTS NONE 2 D model is to be stored 3 D model is to be stored this is the default mode Control storing of a set on the Input Interface File Name of a previously defined set Both nodes and elements are stored Only nodes are stored Only elements are stored Neither nodes nor elements are stored Prefem SESAM 5 262 01 JUN 2003 Program version 7 1 WRITE WRITE superelement number PURPOSE The command writes the Input Interface File Note Normally the writing of the Input Interface File is controlled by Manager see Section 2 13 1 SESAM Prefem Program version 7 1 01 JUN 2003 5 263 ZOOM FRAME IN ZOOM OUT OFF REDISPLAY OFF define zoom area PURPOSE The command zooms the display in and out PARAMETERS FRAME The currently displayed part of the model will fill the display area IN Zoom in by defining the area to magnify OUT Zoom out by defining the area into which the current display will be fitted define zoom area Use the mouse to define two diagonal points of the rectangula
92. point P1 and then P2 relative to P1 by adding 10 in X direction and subtracting 2 in Y direction Figure 3 11 shows the two points defined DEFINE POINT P126 4 DEFINE POINT P2 P1 DX 10 DY 2 gt SESAM Prefem Program version 7 1 01 JUN 2003 3 17 PI 10 P2 Figure 3 11 Defining points The command parameter lt opens an update mode for specification of point coordinates Having given the command DEFINE POINT P2 lt the current coordinates the last given are echoed on the screen e g X 2 000E 00 Y 6 000E 00 Z 4 000E 00 The following options are then available for updating changing these initial coordinates another point name e X Y e Z DX DY DZ SHAPE INTERSECTION POINT INTERPOLATION MOVE BY TRANSFORMATION USE LOCAL COORDINATE SYSTEM The X Y Z options followed by a value will replace the corresponding coordinates The DX DY DZ options will add a given value to the corresponding coordinates After each update the current coordinates are echoed on the screen When satisfied the command parameter gt is given to confirm the point coordi nates and close the update mode Within this update mode real values may also be entered as expressions see Section 3 5 10 and parameters see Section 3 8 Of the other updating alternatives listed above the POINT INTERPOLATION and SHAPE INTERSEC TION are exemplified below and illustrated in Figure 3 12 Prefem SES
93. points from the outside towards the inside Imaginary normal pressure Entering END implies that the load is real The pressure is applied to the inside of the surfaces The pressure is applied to the middle of the surfaces The pressure is applied to the outside of the surfaces The pressure is applied to the inside of the specified layer The pressure is applied to the middle of the specified layer The pressure is applied to the outside of the specified layer Layer number see Section 3 10 2 Prefem SESAM 5 160 01 JUN 2003 Program version 7 1 PROPERTY LOAD load case PART LINE PART LINE _ line GLOBAL TRANSFORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam DEG PHASE ANGLE phx phy phz IMAGINARY COMPLEX ifx ify ifz fx fy fz point dist point2 dist2 RAD PHASE ANGLE phx phy phz END INSIDE SURFACE SHELL ELEMENT MIDDLE SURFACE SHELL ELEMENT OUTSIDE SURFACE SHELL ELEMENT BEAM ELEMENTS MEMBRANE ELEMENT MIDDLE LAYER LAYERED ELEMENT layer PURPOSE The command defines partially distributed line loads forces of constant magnitude acting on lines The part line load must be defined to be acting on either beam elements membrane elements or shell ele ments If the load is defined to be acting on say a beam element but only shell elements are present the
94. previously defined coordinate system The cylindrical or spherical coordinate system is employed without any further transformation The hinge stiffnesses are given as coefficients of fixation The coefficient of fixation of d o f number i The hinge stiffnesses are given as elastic spring stiffnesses The elastic spring stiffness of d o f number i The elastic spring stiffness of d o f number i is infinitely high SESAM Program version 7 1 Prefem 01 JUN 2003 5 135 PROPERTY INITIAL DISPLACEMENT INITIAL DISPLACEMENT select geometry fx fy fz mx my mz GLOBAL TRANSFORMED trnam PURPOSE The command specifies the values of an initial displacement for nodes This is relevant for a dynamic anal ysis only PARAMETERS select geometry fx fy fz GLOBAL TRANSFORMED trnam Select geometry See Section 5 1 on how to perform a selection Initial displacement in the X direction Initial displacement in the Y direction Initial displacement in the Z direction Initial rotation about the X axis given in radians Initial rotation about the Y axis given in radians Initial rotation about the Z axis given in radians The values refer to the cartesian coordinate system of the model The values refer to a transformation of the cartesian coordinate system Name of a previously defined transformation Prefem 5 136 SESAM
95. scale the one cal culated by the AUTO option Set a shrink factor for display of elements The legal range is 0 1 1 0 Switching off shrunken mode is done by giving the value 1 0 Change the sizes of symbols like geometry and mesh names etc See separate explanation of the command Choose between 1 2 and 4 viewports Prefem SESAM 5 226 01 JUN 2003 Program version 7 1 Two viewports will initially display the model in both view ports The right hand viewport is then available for zooming The left hand viewport will display the whole model and a bro ken square indicating the zoomed in area Zooming may also be performed in the left hand viewport but the right hand view port will then not indicate the zoomed in area by a broken square If the model has already been zoomed when switching to two viewports then the right hand viewport will show the zoomed view and the left hand viewport the whole model with a broken square indicating the zoomed in area Switching to four viewports will display the model projected into the X Z Y Z and X Y planes The fourth viewport will display the current model and viewpoint Zooming is possible in all viewports SESAM Program version 7 1 01 JUN 2003 SET GRAPHICS COLOUR LOAD VALUE LEVELS number of levels BODY NAMES BLACK BOUNDARY CONDITIONS ELEMENT NUMBERS LIGHT BLUE GEOMETRY LINES LINE NAMES
96. set The selected elements are checked successively for all specified criteria and stored in the same set until END is given The set of failing elements may be printed or displayed PARAMETERS select elements set of failed elements ANGLE MINIMUM MAXIMUM BOTH MINIMUM AND MAXIMUM min max ASPECT RATIO ratio Select elements to be checked See Section 5 2 on how to per form a selection Name of a new set to be created within this command Check the element corner angle 1 D elements beam truss spring etc and contact elements cannot be checked Check for small angles Check for large angles Check for both small and large angles Smallest acceptable value of small angles Largest acceptable value of large angles Check the element aspect ratio The aspect ratio of an element is the longest distance between two nodes of the element divid ed by the shortest distance between two nodes Only corner nodes of the elements are considered The largest acceptable value of the aspect ratio Prefem SESAM 5 44 01 JUN 2003 Program version 7 1 REPORT FAILING ELEMENTS The elements failing will be listed on the screen in addition to being stored in the set TWIST Check the element twist in terms of twist or rotation of its edg es Only 2 D elements i e shell membrane and axisymmetric elements are checked The twist of an edge of an element is the angle by which the edge is twisted It is calculated as
97. sizes of line divisions i e number of elements for lines default is 2 Alter the sizes of line names default is 2 Alter the size of the maximum load arrow default is 15 Alter the sizes of load values default is 2 Alter the sizes of material names default is 2 Alter the sizes of node numbers default is 2 Alter the sizes of node symbols see the LABEL command default is 1 Alter the sizes of spring damper and mass elements default is 2 Alter the sizes of the origin symbol default is 10 Alter the sizes of point names default is 2 Alter the sizes of point symbols the X default is 1 5 Multiply symbolic representation of cross sections and element thicknesses by this factor default is 2 This label is presently not available Alter the sizes of surface names default is 2 Alter the sizes of surface normal default is 6 For most options Give symbol size in millimetres legal range is 1 0 100 0 For option FACTOR factor used on all labels For option SECTION FACTOR factor on thickness sections and eccentricities Prefem SESAM 5 236 01 JUN 2003 Program version 7 1 SET INSIDE OUTSIDE POINT point name COORDINATES x y z INSIDE X Y select surfaces corner point X OUTSIDE Y Z PURPOSE The command defines the inside outside of a surface This definition is used in applying normal pressure loads see Section 3 12 3 A cor
98. this manual in particular the sections of Chapter 3 and the description of all Prefem commands in Chapter 5 This manual is otherwise organised as follows Chapter 2 FEATURES OF PREFEM contains an introductory description of the major features of Prefem Chapter 3 USER S GUIDE TO PREFEM explains how to go about creating a complete model ready for analysis All major features and several minor features are described The chapter does not contain a full description of all program features though a complete understanding of all features of Prefem can only be obtained through training in use of the program while referring to Chapter 5 Chapter 4 EXECUTION OF PREFEM contains more special information not intended for the new user who will be using Manager to control his SESAM analysis The chapter explains how to start Prefem outside Manager and operate it in line mode not using the graphical user interface The files used by Prefem are also explained Practical information is provided on how to operate Prefem and manipulate its files in vari ous ways Built in and hardware dependent requirements and limitations are also described Chapter 5 COMMAND DESCRIPTION explains in detail all commands of Prefem The commands and subcommands are sorted alphabetically Appendix A TUTORIAL EXAMPLES contains a couple of examples of use Appendix B THEORY contains the formulae employed by the program for computing sectional parameters for the various types of
99. to e Get started using the graphical user interface See Section 3 1 Create a small but complete model a brief tutorial See Section 3 2 Define the geometry model See Section 3 3 Create the FE model by determining the element discretisation selecting element type s and requesting automatic creation of the FE mesh See Section 3 4 Define and assign connect properties material data boundary conditions etc See Section 3 5 Define oads See Section 3 6 Give varying value functions input for properties especially loads See Section 3 7 Define and use parameters See Section 3 8 Select geometry and using sets and wild cards for the same purpose See Section 3 9 Define special element types spring damper mass sandwich and layered elements See Section 3 10 Define and use transformations and coordinate systems See Section 3 11 Display verify and check the FE model See Section 3 12 Prefem SESAM 3 2 01 JUN 2003 Program version 7 1 3 1 Getting Started the Graphical User Interface Prefem is started from the SESAM Manager by clicking Model General Prefem See Section 4 1 3 for how to start Prefem outside Manager Unix only The main part of the graphical user interface is the graphic mode window The appearance of this window is principally the same on PC Windows and Unix On PC there are also a print window and a message win dow Print requested by the user appears in the print window whereas v
100. to solid elements Note If the node is on a surface with a cylindrical or spherical coordinate system assigned to it see the SET MESH command i e the surface is not projected onto a shape the node may be moved off the surface Note It may prove difficult to improve a mesh manually by this command You may find that the only way to get an acceptable mesh is to change the data determining the mesh i e the number of elements or maximum element size for lines and mesh corners Prefem SESAM 5 32 01 JUN 2003 Program version 7 1 Note No mesh smoothing will be performed E g mid side nodes of eight node shell elements will not be moved when corner nodes are moved PARAMETERS select surfaces Surfaces for which nodes shall be moved See Section 5 1 on how to perform a se lection DISPLAY Display the mesh of the selected surface s only Note that this command will not be logged It has meaning for graphic mode only select and move node Position the cursor over the node you want to move and press and hold the left mouse button LMB Drag to the new position of the node and release the LMB This action will be logged as three sets of coordinates The first point and second point in space on a line normal to the screen identifying the node to be moved and the distance in space by which the node is moved Note that entering the three sets of coordinates manually is awkward and of little practical interest SESAM Prefem Pro
101. used to check whether two elements have the same tem perature load value in nodes that the elements have in common The default value is 0 0 Tolerance used in load printing Set the tolerance for snapping to existing points when using the graphic feature for cutting within the CUT command The snap tolerance is given in millimetres as measured on the screen The snap tolerance is automatically converted to mod el units depending on the current zoom factor Note that if the converted snap tolerance becomes smaller than the coordinate tolerance then the latter will be used Snap tolerance for graphic cutting The default value is 2 0 Set a tolerance used for checking whether two vectors are par allel The cross product is checked Vector parallel check tolerance the default value is 0 001 SESAM Prefem Program version 7 1 01 JUN 2003 5 261 SET WRITE MODE 2DIMENSIONAL 3DIMENSIONAL ALL WRITE MODE NODES INCLUDE SET set name ELEMENTS NONE PURPOSE The command sets the mode for writing the Input Interface File The user has the option to generate the Input Interface File describing the FE model either as a 2 D or a 3 D model The SET WRITE MODE command enables the user to specify which type of model file is to be gen erated For the 2 D model the degrees of freedom corresponding to the translation in Y direction and the rotations about the X and Z axes are fixed A 2 D model in the X Z
102. what The parameter names above each represent several parameters as detailed in the following The EXTRUDE command is described in principle below for a complete description see the command description in Chap ter 5 copy geometry Select geometry to copy A prefix for the geometry names of the copies is given to enable identifying the copies later on Prefem SESAM 3 34 01 JUN 2003 Program version 7 1 extrude geometry Select geometry to extrude Points are extruded to lines lines to surfaces and sur faces to bodies A prefix for the names of the extruded geometry is given to enable identifying this later on coordinate system Select the global cartesian or a specified cylindrical coordinate system for the copy extrusion operation copy extrude vectors Give the number of copies extrusions to make The corresponding number of vec tors are given one by one or several at a time extrude what Choose whether and what to extrude copy only do not extrude anything extrude points to lines extrude lines to surfaces extrude surfaces to bodies 3 3 9 The GENERATE Command versus the EXTRUDE Command The GENERATE and EXTRUDE commands have overlapping application areas several types of models may be created by either command They differ however in that EXTRUDE involves a bottom up while GENERATE more of a top down approach to modelling This different approach to modelling may be explained as follows n order to take full advanta
103. whole or selected geometry shapes elements and nodes See section Section 3 12 1 for examples of use of this command PARAMETERS BODY SURFACE LINE POINT select geometry GEOMETRY MESH SHAPE select shapes ELEMENT select elements Display selected bodies and surfaces lines and points Display selected surfaces and lines and points Display selected lines and points Display selected points Select geometry to display See Section 5 1 on how to perform a selection Display the whole geometry Display the whole element mesh Display selected shapes with broken lines Except for the sphere the shapes are in finite in space They are nevertheless displayed limited by the points defining them Shapes are selected in a similar way as geometry see Section 5 1 Wild card may however not be used for selecting shapes their names must be given explicitly Display selected elements Select elements to display See Section 5 2 on how to perform a selection SESAM Prefem Program version 7 1 01 JUN 2003 5 97 NODE Display selected nodes select nodes Select nodes to display See Section 5 2 on how to perform a selection Prefem SESAM 5 98 01 JUN 2003 Program version 7 1 EXIT EXIT PURPOSE The command terminates the execution of Prefem Note As explained in Section 2 13 1 whether or not to write the Input Interface File is normally controlled by Manager If you want to produce t
104. 01 JUN 2003 5 61 Figure 5 19 Cylindrical and spherical coordinate systems Prefem SESAM 5 62 01 JUN 2003 Program version 7 1 DEFINE DAMPER AXIAL name point point2 material name DAMPER GLOBAL TO GROUND name select points material name TRANSFORMED J trnam PURPOSE The command defines a single axial damper element between two points or several damper to ground ele ments connected to points The dampers are given names and their material data damping characteristics must previously have been defined by the PROPERTY MATERIAL command Dampers are automatically connected to the nodes cre ated at the points and given element numbers The dampers are created by the MESH command The DELETE MESH command deletes the dampers but not their definitions meaning that when the mesh is re created e g by MESH ALL the dampers will be re created The DELETE DAMPER command how ever deletes the definition of dampers A damper to ground may have from one and up to six degrees of freedom this is specified in the PROP ERTY MATERIAL command PARAMETERS AXIAL Define an axial damper TO GROUND Define a damper to ground name User given name of the damper s point1 Name of the point to which end 1 of the axial damper is to be connected point2 Name of the point to which end 2 of the axial damper is to be connected select points material name Select points where damper to ground ele
105. 1 point2 factor SHAPE INTERSECTION shapel shape2 shape3 USE LOCAL COORDINATE S YSTEM coord name GLOBAL SESAM 01 JUN 2003 Program version 7 1 The additions to the current values Previously defined param eters may be used here Update cartesian coordinates by specifying new values Corre spondingly for cylindrical and spherical coordinate systems The new values Previously defined parameters may be used here Update current coordinates to those of the previously defined point with name point name Update current coordinates by moving according to the given transformation A previously defined transformation Update current coordinates to the interpolation point between two points An interpolation factor defines the new current co ordinates as a point on the line between point and point2 If the factor is equal to 0 the current coordinates will be at point if equal to 1 the current coordinates will be at point2 Values out side the range 0 to 1 will imply extrapolation Name of a previously defined point Name of a previously defined point The interpolation factor Update current coordinates to the intersection point between three shapes The current coordinates are used to select one of the possibly two or more intersection points Therefore the cur rent coordinates should be in the vicinity of the desired inter section point prior to giving the SHAPE INTERSECTION command See Figure 5 25 Name
106. 1 01 JUN 2003 5 177 PROPERTY MATERIAL material name ANISOTROPIC 2D ELEMENT 2D ELEMENT q1 q2 q3 rho dil d21 d22 d31 d32 d33 psl ps2 dampl damp2 alphal alpha2 PURPOSE The command specifies the data for either an anisotropic or orthotropic material for lower order 3 and 4 node shell elements and membrane elements The anisotropic material has two material axes both lying in the element plane The first material axis is determined by projecting a vector Q onto the element plane The second material axis is perpendicular to the first material axis and lies in the element plane PARAMETERS ql q2 q3 Components of a vector Q in the cartesian coordinate system of the model deter mining by its projection onto the element plane the first material axis of the aniso tropic material Note that the vector Q cannot be perpendicular to any of the elements rho Material density dll d33 Terms of the lower triangular part of the general anisotropic elasticity matrix see Equation 5 1 psl ps2 Factors to produce the stress perpendicular to the membrane plane for plane strain problems For a plane stress material which is the normal case these parameters are equal to zero The stress normal to the membrane plane will be calculated as follows On ps1 0 ps2 05 For an isotropic plane strain material ps1 and ps2 are equal to Poisson s ratio dampl damp2 Spe
107. 25 nerit tete t di dee denda ons Ir PU ss doin ceded ite c tfi es e 5 81 DEE UNE SHAPE ifs soc ite corks tothe tothe Mi tue disti ied pp iE 5 83 DERPINE SPEINE etd per hte petere P te i eie rr eet eee E au ee 5 85 DEEBINE SPRENGI 2 nic e ci NE ERR an PUE SE E ERE UR ae Hune HERR inde eges 5 86 DEFINE SURFACE trt n RE Re Per deed re ABER ee Me EXER oy ea ee IER E hee oe ep eere 5 87 DEFINE TRANSFORMATION cineca e a etse aia tts ense E eene th seine tese ent 5 90 DELETE MES H in nee eere aat oed ete RE 5 94 DELETE PROPERTY 5 5 5 n iW eee eee te itr aiii Ries 5 95 YB Fs 2 Bs spe SP eT TEE A euh cos Ioui WE ee Ded es 5 96 EXE iiu ote ime eaa eGR es ed dan Ub 5 98 I Qu DIDI 5 99 GENEBRATE unanime qr E eI Rd nei s 5 102 HELP uaea a aaa a este dv itte eiut be etetecs bee Hsu hec tese 5 105 JOING 5 ee SSeS dott a sito P dus 5 106 LABE Dardi TE PET 5 107 LABEL COLOUR IDENTIFICATION cornici nnne ia ATA ARE AAE AAR TAA 5 110 LABEL NODE SYMBOL renin N TAE a 5 111 LEOC ATE cette eot SNR OER EAE EAE AA ARR NA A AA 5 112 IMPS r EIE IE EAEE AEE AENA EA to ute E EAE E S RO QU E E EAE 5 113 15 E 91 E m SE E A T A E O IN AE A ER REN 5 115 PRINT nirean e MEAS ER eRe RS A dee e reete 5 117 PROPER TI de iie teer fase ti dacs potas ETEA NAON RENET dos 5 126 PROPERTY BOUNDARY CONDITION 0 ccccccccccccccccessscccessscccsssseccsessscesesssecessssecesssseeessaes 5 128 PROPERTY CENNCGBE etit enter tree erri Teeth ete da Soe Da dos pues eo
108. 3 4 1 Set control information for mesh especially mesh corner types for surfaces Set mesh corner for surfaces the SET MESH command may also be used for the same purpose Set parameters controlling the creation of the finite element mesh Control the new geometry names created when cutting geome try Set not mesh corner for surfaces the SET MESH command may also be used for the same purpose Set number of elements for lines see Section 3 4 1 Define outside of surfaces for the benefit of pressure load ap plication see Section 3 12 3 This feature 1s presently not active This feature 1s presently not active Set name of plot file plot format and other plot parameters Set a prefix for geometry names a string that 1s put in front of subsequently created geometry names Set print destination screen or file name of print file and oth er parameters Prefem SESAM 5 214 01 JUN 2003 Program version 7 1 PROJECTION Set projection onto a shape of mesh for selected surfaces TASK Suppress commands irrelevant for the current task TOLERANCE Set tolerances used by the program to determine whether two values are equal e g in checking geometric coincidence WRITE MODE Decide whether or not defined sets are to stored on the Input In terface File SESAM Prefem Program version 7 1 01 JUN 2003 5 215 SET COMMAND INPUT FILE COMMAND INPUT FILE file prefix file name PURPOSE The co
109. 31 d32 d33 d4l d42 d43 d44 d51 d52 d53 d54 d55 d61 d62 d63 d64 d65 d66 The axes of the anisotropic elasticity matrix are parallel with the cartesian coordinate system of the model The material axes of the anisotropic elasticity matrix are paral lel with the specified transformed coordinate system Name of a previously defined transformation Material density Terms of the lower triangular part of the general anisotropic elasticity matrix see Equation 5 7 Specific damping coefficients for the three material axes of an isotropy Thermal expansion coefficients for the three material axes of anisotropy The lower triangular general anisotropic elasticity matrix 5 7 SESAM Prefem Program version 7 1 01 JUN 2003 5 183 NOTES An orthotropic material is defined by taking advantage of the fact that it is a special case of the anisotropic material To define an orthotropic material in its principal axes the lower triangular part of the general aniso tropic elasticity matrix should have zero values for some of the terms dll d21 d22 d31 d32 d33 5 8 0 0 0 d44 0 0 0 0 d55 0 0 0 0 0 d66 Prefem SESAM 5 184 01 JUN 2003 Program version 7 1 PROPERTY MATERIAL material name DAMPER AXIAL damp TO GROUND n cij p DAMPER PURPOSE The command defines the damping coefficient of an axial damper and the damping matrix of a damper to ground PARAMETERS AXIA
110. 7 illustrates a mesh for the same surface with only one mesh corner And Figure 3 38 illustrate a mesh for the same surface with no mesh corners Figure 3 39 shows a special case for which five mesh corners are allowed there can be only one element edge in between two of the mesh corners Figure 3 40 shows a radial mesh with triangular elements This mesh which is suitable in the middle of a sector shaped geometry is created when the following conditions are met The triangular surface has three mesh corners Two of the lines are discretisised into only one element edge the third line curve which may also be several lines curves with not mesh corner in between may have any number of elements Triangular elements are requested Figure 3 41 shows an alternative mesh for a sector shaped geometry This mesh is created when the fol lowing conditions are met Define the centre of the sector as a cut corner use the command SET MESH CORNER TYPE CUT CORNER Let the two lines joining in the cut corner have equal number of elements Figure 3 42 shows more alternative meshes for a sector shaped geometry Comparing the left most of the three meshes with the mesh of Figure 3 41 it is seen that the only difference is that the number of ele ments for the arc has been changed from 6 to 7 Since the sum of elements around the surface is now an odd number a triangular element is inserted in the cut corner The other two alternat
111. AL INFINITY X GLOBAL INFINITY Y GLOBAL INFINITY Y GLOBAL INFINITY Z GLOBAL INFINITY select lines Z GLOBAL INFINITY GUIDING POINT DIRECTION FROM FIXED POINT X y Z TOWARDS FIXED POINT PURPOSE The command defines local coordinate systems for beams elements A new definition of local coordinate systems for the same element will override the former definition Local coordinate systems cannot be deleted For beam elements for which no local coordinate system has been defined a default condition takes effect as explained below The element local x axis is by definition the neutral axis of the cross section and points from the first node towards the second node The first and second nodes are implicitly defined by the command defining the lines The local y z plane is normal to the local x axis Defining a local coordinate system involves deter mining the orientation of either of the local y and z axes The right hand rule determines the third local axis The orientation of the local y and z axes is defined by either determining the orientation of y x plane or the z x plane These planes are given an orientation by use of a guiding point This guiding point may be defined by Specifying its location relative to end 1 of the element GUIDING POINT DIRECTION Giving its coordinates directly FROM FIXED POINT and TOWARDS FIXED POINT Positioning it infinitely far away along any of t
112. ALCULATED NEGATIVE Z OFFSET and CALCU LATED POSITIVE Z OFFSET options Given that in this case the local z axes of the girders are paral lel with the global Z axis see the PROPERTY LOCAL COORDINATE BEAM for more information on this the girders of the deck must be moved in the negative local z direction down while the centre line girder must be moved in the positive local z direction up Use the SET MAX ELEMENT LENGTH command to set the maximum element length for all surfaces and implicitly all lines to 4 Prefem SESAM 3 14 01 JUN 2003 Program version 7 1 Use the MESH ALL command to create the FE mesh i e nodes and elements Click the Shortcut command Display Mesh to display the mesh and see that there are triangular ele ments in the bilge area of the bulkhead and frames To improve the mesh in these areas do as follows Use the SET DEFAULT ADJUST MESH ON command or click the Shortcut command Default Mesh adj to set Prefem in a mode in which a change in mesh density number of elements along lines involves a re meshing If necessary Prefem will automatically adjust the mesh density other places too to be able to create a mesh for the whole model Use the Shortcut command Display Geometry to display the geometry Use the SET NUMBEROF ELEMENTS command to reduce the number of elements along the three short lines parallel with the Y axis and next to the bilge from 2 to 1 Remember to start
113. AM 3 18 01 JUN 2003 Program version 7 1 P3 is defined by interpolating between P1 and P2 DEFINE POINT P3 lt POINT INTERPOLATION P1 P2 0 3 gt P4 is defined by intersecting three pre defined shapes two planes and a sphere Note that the coordinates to update by the shape intersection the initial coordinates of P4 must be in the vicinity of the intersection sought in order to pick the proper intersection point if there is more than one DEFINE POINT P4 SHAPE INTERSECTION SH1 SH2 SH3 gt initial position of P4 Figure 3 12 More on defining points Defining Lines Curves A line curve is defined by a start and an end point plus a rule to determine the shape of the line curve Table 3 1 shows these definitions for the various types of line curve How to define lines and curves is exemplified below and illustrated in Figure 3 13 through Figure 3 15 Note Mathematically all lines and curves are described as B splines between start and end points A B spline is a combination of polynomial functions and is capable of representing any complex curve A circular arc is therefore not exactly an arc but rather a B spline very close to the arc Table 3 1 Lines curves and their definitions Type Definition Line Straight line between two points Arc Circular arc defined by two points and a centre point Intersection between two shapes and between two points a third point picks the Intersection prop
114. ANSFORMATION Prefem 01 JUN 2003 5 57 Define the geometry entity line curve of type intersection Define the element type layered shell element Define the geometry entity line curve of type straight line Define the element type mass element Define the geometry entity line curve of type node line Define a parameter a value that later can be used in place of a real value Define the geometry entity point Define the geometry entity body in a simplified way Define a rounded corner i e round off a corner by creating an arc where two lines meet Define a sector corner i e cut the corner of a surface by an arc having the surface comer point as its centre Define a set a selection of geometry nodes or elements Define a shape a tool used for creating geometry and forming FE mesh Define the geometry entity line curve of type spline Define the element type spring Define the geometry entity surface Define a transformation Prefem SESAM 5 58 01 JUN 2003 Program version 7 1 DEFINE ARC ARC name start point end point centre point nelm PURPOSE The command defines the geometric entity arc The angle of the arc must be less than 180 degrees If the distance between centre point and start point is different from the distance between centre point and end point then the arc is not circular but rather an arc with linearly varying radius PARAMETERS name User
115. BEAM ECCENTRICITY BEAM select lines CALCULATED NEGATIVE Z OFFSET CALCULATED POSITIVE Z OFFSET LOCAL COORDINATE OFFSET ONE END LOCAL OFFSET point PURPOSE The command defines eccentricities for beam elements The eccentricity can be specified in beam element local coordinates or applied automatically by Prefem PARAMETERS select lines CALCULATED NEGATIVE Z OFFSET CALCULATED POSITIVE Z OFFSET LOCAL COORDINATE OFFSET ONE END LOCAL OFFSET point Select lines for which beam elements shall have eccentricities See Section 5 1 on how to perform a selection The eccentricity is automatically determined to let the beam section be welded or attached onto the surface of the plate or shell Both the beam sectional data and plate shell thickness are taken into account these data must therefore have been defined already The beam is given eccentricity shifted in the negative beam local z direction see Figure 5 37 The eccentricity is con stant along each line unless the plate shell thickness varies Same as CALCULATED NEGATIVE Z OFFSET only the beam is given eccentricity shifted in the positive beam local z direction The eccentricity is specified in beam element local coordinates as a vector from the nodes to the beam ends and midpoints for 3 node beam elements The eccentricity is constant along the beam The eccentricity is specified in beam element local coordinate
116. CKNESS command must be used after the CHANGE NODE command or else the node may have incorrect thickness it will retain its thickness from the original position SESAM Prefem Program version 7 1 01 JUN 2003 5 35 CHANGE NORMAL OF SURFACE ROTATION OF SURFACE X GLOBAL INFINITY Y GLOBAL INFINITY Z GLOBAL INFINITY X GLOBAL INFINITY NORMAL OF SURFACE Y GLOBAL INFINITY Z GLOBAL INFINITY FROM FIXED POINT GUIDING POINT DIRECTION x y z TOWARDS FIXED POINT select surfaces ROTATION OF SURFACE PURPOSE These two commands have the same purpose To set the direction of the local z axis of shell membrane ele ments The NORMAL OF SURFACE option sets the z axes explicitly while the ROTATION OF SUR FACE option reverses the current directions When a surface is defined the borderlines are sorted in a certain sequence This rotational sequence defines by the right hand rule a surface normal which in turn determines the element z axes The direction of the z axis of an element determines the direction of the normal pressure type of loading this may be overruled though see the SET INSIDE OUTSIDE command The z axis direction is also of consequence for the interpretation of results if two neighbouring and co planar surfaces have opposite normals then the results are easily misinterpreted Setting or changing the surface normal may thus be necessary In the NORMAL OF SURFACE op
117. CTOR a This option is presently inactive PURPOSE The command prints selected information on the screen or to a print file 5 117 Prefem 5 118 PARAMETERS ALL STATUS BODY SURFACE LINE POINT select geometry GEOMETRY PROPERTY SET set name SHAPE select shapes SPRING DAMPER select spring dampers ELEMENT select elements BASIC ELEMENT ECCENTRICITY LOCAL COORDINATE SYSTEM NODE select nodes SESAM 01 JUN 2003 Program version 7 1 Generate a print file containing a complete printout of all de fined and created data Print key information on the model Print information on selected bodies Print information on selected surfaces Print information on selected lines Print information on selected points Select geometry to be printed See Section 5 1 on how to per form a selection Print geometrical information Print property type information Print information on selected sets Name of a set name Print information on selected shapes Shapes are selected in a similar way as geometry see Section 5 1 Wild card may however not be used for selecting shapes their names must be given explicitly Print information on selected spring and or damper elements The spring and damper elements are selected in a similar way as geometry see Section 5 1 Wild card may however not be used for selecting shapes their names must be given explicitly Print information on selec
118. DIVISIONS LINE NAMES LOAD ARROW SIZE SIZE SYMBOLS LOAD VALUES value MATERIAL NAMES NODE NUMBERS NODE SYMBOLS ONE NODED ELEMENT SYMBOLS ORIGIN SYMBOLS POINT NAMES POINT SYMBOLS SECTION FACTOR SHAPE NAMES SURFACE NAMES SURFACE NORMAL PURPOSE The command specifies alters the sizes of symbols appearing in the display and plot The sizes are given in millimetres approximately PARAMETERS BODY NAMES Alter the sizes of body names default is 2 BOUNDARY CONDITION SYMBOLS Alter the sizes of boundary condition symbols default is 7 5 SESAM Program version 7 1 ELEMENT NORMAL ELEMENT NUMBERS ELEMENT THICKNESS ELEMENT TYPES FACTOR GEOMETRY NAMES LINE DIVISIONS LINE NAMES LOAD ARROW SIZE LOAD VALUES MATERIAL NAMES NODE NUMBERS NODE SYMBOLS ONE NODED ELEMENT SYMBOLS ORIGIN SYMBOLS POINT NAMES POINT SYMBOLS SECTION FACTOR SHAPE NAMES SURFACE NAMES SURFACE NORMAL value Prefem 01 JUN 2003 5 235 Alter the sizes of 2 D element normals default is 2 Alter the sizes of element numbers default is 2 Alter the sizes of element thickness values default is 2 This label is presently not available Multiply all current label sizes by this factor The factor has no influence on LOAD ARROW SIZE ORIGIN SYMBOL and SECTION FACTOR Alter the sizes of all geometry names default is 2 Alter the
119. DY ACCELERATION RIGID BODY VELOCITY TEMPERATURE TO MASS PURPOSE SESAM Program version 7 1 The command defines loads on the model Loads are identified by consecutive load case numbers 1 2 3 x A single load case may contain all and any of the load types listed above and explained in more detail in the following Loads refer to geometric entities bodies surfaces etc the program will automatically transfer the loads to the FE model the nodes and elements Loads are accumulated on the geometry That is if more than one PROPERTY LOAD command is given referring to the same load case and the same geometry then the sum of the given loads will be taken into account Loads may be simple real loads or complex loads consisting of real and imaginary parts After entering the real components of a load the command END is entered if the load is to be real By entering the imaginary components the load implicitly becomes complex Refer to Section 3 6 for an introduction to defining loads SESAM Program version 7 1 PARAMETERS BEAM CONCENTRATED COMPONENT PRESSURE CONCENTRATED GRAVITY HYDRO PRESSURE LINE LOAD LINE MOMENT NORMAL PRESSURE PART LINE PRESCRIBED ACCELERATION PRESCRIBED DISPLACEMENT RIGID BODY ACCELERATION RIGID BODY VELOCITY TEMPERATURE TO MASS Prefem 01 JUN 2003 5 145 Define concentrated load force on beam element Define component surface pressure Define conce
120. Default switches back to the default viewing position optionally set in Manager and re dis plays the model Prefem SESAM 3 6 e e e 01 JUN 2003 Program version 7 1 Zoom In zooms in by either clicking twice and diagonally or by pressing the LMB and drag ging it to form a zoom area rubber band box Zoom Fr re displays the model so that it fits within the display area Refresh refreshes the display with the last setting Misc e e e e Learn offers making a new Shortcut command Click the button and enter a maximum eight character string being the name of the new Shortcut command and hit Return Now give any sequence of commands Several complete commands may be given the last of which may be incomplete 1 e more data is required to make it complete Clicking the learn button once more completes the process and the new Shortcut command appears as a new button Info toggles switches on and off a mode offering quick information on geometric items When the button is depressed clicking geometry provides information on the clicked items This is typically point coordinates line and surface properties etc In addition the distance between points as well as angle between lines with a common end point are printed when points lines are shift clicked The information appears in the print window line mode window on Unix Note that when the button is depressed geometry cannot be selected by c
121. E elements has been increased to 2 6 2 4 starting at the lower line and going anti clockwise There will always be at least one stiffener displayed per element involving that the spacing between the stiffeners will be too small for small elements Also the display tend to give a somewhat confusing impression spacings too small Figure 5 22 Display of layered elements for verification purposes It should be noted that the results produced for layered elements by the structural analysis program Sestra consist of layers with stress components for each Le there will be stress components for an idealized ortho tropic layer rather than forces and moments for the stiffeners Each layer will have stress components as for an eight node shell element The postprocessor Xtract offers these stress components through a selection of layer and for each layer two surfaces the upper and lower See Xtract for more information on this Prefem SESAM 5 68 01 JUN 2003 Program version 7 1 DEFINE LINE LINE name start point end point nelm PURPOSE The command defines the geometric entity line Multiple line definition is possible by using wild card names Wild card names may be used for the name of the line and the start and end points For defining lines an extra wild card feature is available through use of the plus and minus signs this is explained in Section 3 9 3 PARAMETERS name User given name of th
122. E A F C 2B G AREA HA HZ TB TT 2 HB BY TY IX 4 HA HB HB TB HB TT 2HA TY IY BY TB TT 2TY D 12 E H AY F C Hy 2G B HY IZ TB TT BY 2D TY VID G AB 5 IYZ 0 WXMIN IX HB HA HA HB WYMIN IY MAX HZ H H WZMIN 2IZ BY SY E H A H TBY TY SZ TB TT BY 8 G HB 2 SHARY IZ SZ TB TT SFY SHARZ IY SY 2TY SFZ SHCENY 0 SHCENZ C H TB HA TB TT CY BY 2 CZ H SESAM Program version 7 1 01 JUN 2003 B1 3 Channel section B 1 3 1 HZ BY TZ TY SFY SFZ POSWEB B 1 3 2 Sectional Dimensions Height Width of top and bottom flanges Thickness of top and bottom flanges Thickness of web Shear factor y direction Shear factor z direction for web location in positive y direction otherwise 1 A HZ lt BY Negative Figure B 3 Channel section Sectional Parameters Computed Prefem APPENDIX B 7 Positive The expressions below for LX IY IZ WXMIN WYMIN WZMIN SHARY and SHARZ are taken from Ref 1 The expressions for SHCENY and SHCENZ are taken from Ref 2 A HZ 2TZ AREA 2BY TZ A TY Y QTZ BY A TY 2AREA Z HZ 2 Prefem SESAM APPENDIX B 8 01 JUN 2003 Program version 7 1 IX TY 2BY A 2 6TY 3 If TZ TY then WXMIN IX TY TR a 11208Y TZ A TY 3 WXMIN IX MAX TZ TY IY TY A 12 2 2 BY TZ 12 BY TZ 4 TZ 2y IZ 2 TZ BY 12 TZ B
123. E MESH command You may then modify the data determining the element discretisation and create a new mesh Note For large models the MESH command may require some time During processing of the com mand you may use Shift Esc to abort it This will have no effect on the program execution apart from incomplete execution of the command in question and you may continue model ling This is available on PC only a similar feature is not available on other operating systems The following factors will determine the mesh to be created The geometry of the lines surfaces and bodies to be meshed The direction of the definition of lines and surfaces Prefem SESAM 3 38 01 JUN 2003 Program version 7 1 In some cases the start and finishing point of a surface The number and relative size of the elements along the lines curves of the surfaces The definition of mesh corner types of the surfaces use command SET MESH CORNER TYPE The setting of the MESH PARAMETER use command SET MESH PARAMETER Note Beam and shell elements have 6 d o f s while solid elements have 3 d o f s These element types may be used in the same model and have common nodes provided that the beam and shell ele ments are created before the solid elements This ensures that the nodes get 6 d o f s The MESH ALL command follows this meshing sequence If you create mesh on parts one by one then you must see to yourself that the meshing sequence is correct Note Truss e
124. ECTION command for an explanation of the parame ters SHARY modified SHARY program Sfy SHARZ q SHARZ sfz modifie program SESAM Prefem Program version 7 1 01 JUN 2003 5 195 NOTES The double bottom section should be used with care This is because the sectional properties are calculated in the same way as for the symmetrical I section Only the torsional moment of inertia is increased to take into account the shear flow along the top and bottom plates The effects in other directions are not consid ered Prefem 5 196 SESAM 01 JUN 2003 Program version 7 1 PROPERTY SECTION section name GENERAL GENERAL area ix ly iz iyz wxmin wymin wzmin shary sharz shceny shcenz sy sz PURPOSE The command defines a general section All sectional data are defined directly The following should be noted For beams the area and moments of inertia are required while only the area is required for trusses The product of inertia Lyz is zero for all bi symmetrical sections The minimum sectional moduli Wy Wymin and Wzmin are required by FRAMEWORK Shear deformations will not be accounted for if the shear areas are zero The shear centre location must be specified if the shear centre does not coincide with the element axis The static area moments are used in connection with un symmetrical sections Iy7 0 to re compute sec tion va
125. ERFACE LINE INTERFACE PICK HEADER NONE NOHEADER HEADER SHORT WRITE SUPERELEMENT number NOWRITE SUPERELEMENT COMMAND FILE filename NOCOMMAND FILE General file name prefix General file name Data base journal file status Start the program in line mode Start the program in graphical user interface mode Do not show the program header Do not show the program header Show the standard program header Write an Input Interface File with the given superelement number when exiting the program Do not write an Input Interface File Read the specified command input file after the model journal file has been accepted Do not read a command input file Prefem 4 8 FORCED EXIT NOFORCED EXIT EYEDIR X value EYEDIR Y value EYEDIR Z value PLOT FORMAT format PLOT COLOUR ON or OFF PLOT PAGE SIZE size PLOT ORIENTATION orientation PRINT FORMFEED format WINDOW SIZE size SESAM 01 JUN 2003 Program version 7 1 Force EXIT after initialisation and after processing of the file defined by the COMMAND FILE argument Disable FORCED EXIT Set initial eye direction X value Set initial eye direction Y value Set initial eye direction Z value Set the default plot format to the specified format For legal al ternatives see the SET PLOT FORMAT command Switch colours for plot file on or off Set the default plot page size Set the default plot orientation Set the formfeed page br
126. EXTRUDE command versus the GENERATE command The EXTRUDE command is typically used for creating a 3 D geometry model by extruding a 2 D geometry model for example extruding a plane surface to form a box like model The command is however general and is capable of extruding and copying any type of geometry for example point to line or arc line to plane or cylinder The extrusion may be done in the global cartesian coordinate system or in a cylindrical coordi nate system defined within the EXTRUDE command The EXTRUDE command actually performs a repetitive combined copying and extrusion as illustrated in Figure 3 27 The original geometry is copied and extruded along vectors Notice that the created geometry is the same as the one used to illustrate the GENERATE command in Figure 3 23 copying this line yields these lines extruding this line yields these surfaces vectors X the geometry to copy amp extrude the copied amp extruded geometry Figure3 27 The EXTRUDE command copies and extrudes an original along vectors As is the case for the GENERATE command a single EXTRUDE command will typically replace a number of commands for defining points lines surfaces and if relevant bodies i e a number of DEFINE POINT DEFINE LINE DEFINE SURFACE and DEFINE BODY commands The structure of the com mand is as follows EXTRUDE copy geometry extrude geometry coordinate system copy extrude vectors extrude
127. Example 3 7 illustrates how the geometry used for defining the function points PA and PB does not need to have any relation to the geometry subjected to the load See Section 5 3 for more examples of functions Example 3 5 Defining a Linearly Varying Pressure Load A linearly varying normal pressure is defined as follows PROPERTY LOAD 2 NORMAL PRESSURE ALL SURFACES INCLUDED EXCLUDE AU11 LINEAR 2POINTS VARYING AP13 100 AP33 300 END MIDDLE SURFACE SESAM Prefem Program version 7 1 01 JUN 2003 3 57 Figure 3 51 Linearly varying pressure load Example 3 6 Defining a Sinus Varying Pressure Load A sinus varying pressure 1s defined as follows PROPERTY LOAD 3 NORMAL PRESSURE AU12 AU22 200 SIN LINEAR 2POINTS VARYING AP11 0 AP31 PI END MIDDLE SURFACE Figure 3 52 Sinus varying pressure load Example 3 7 Defining a Hydrostatic Pressure Load A hydrostatic pressure load is defined as follows Prefem SESAM 3 58 01 JUN 2003 Program version 7 1 PROPERTY LOAD 5 NORMAL PRESSURE S LINEAR 2POINTS VARYING PA 0 PB 80 END OUTSIDE SURFACE SWL PA A surface name S Ke r 58 V ED pe Figure 3 53 Hydrostatic pressure on sphere defined as a vertical linear variation Example 3 8 Defining a Load Varying Linearly in one Direction and Parabolic in the Other A linear variation in one direction and parabolic in the perpendicular direction is described by multiplying the two functions a
128. FORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam idx idy idz idrx idry idrz dx dy dz drx dry drz END PURPOSE The command defines prescribed displacements The geometry subjected to the displacements must be given the boundary condition PRESCRIBED DIS PLACEMENT using the PROPERTY BOUNDARY command PARAMETERS select geometry GLOBAL TRANSFORMED LOCAL COORDINATE SYSTEM UNTRANSFORMED trnam coord name dx dy dz drx dry drz idx idy idz idrx idry idrz Select geometry See Section 5 1 on how to perform a selection The displacement components refer to the model s cartesian coordinate system The displacement components refer to a previously defined transformation of the cartesian coordinate system see the com mand DEFINE TRANSFORMATION The displacement components refer to a previously defined cylindrical or spherical coordinate system see the command DEFINE COORDINATE SYSTEM No additional transformation of the cylindrical or spherical coordinate system is performed Name of a previously defined transformation Name of a previously defined coordinate system Displacement components rotations are given in radians Imaginary displacement components By entering data for these the displacement field will implicitly become complex Entering END rather than idx idy idrz implies that the dis placement field is real Prefem SESAM 5 166 01 JUN 2003 Program v
129. Figure 3 40 Radial triangular element mesh for surface with 3 mesh corners a special case Thisis 2 6 lt These sides must have same A quadrilateral element number of elements cut corner L no symbol i Figure 3 41 Quadrilateral element mesh for surface with 2 mesh corners and a cut corner even sum of elements 6 cut corner small cut corner large cut corner j odd number odd sum Figure 3 42 Quadrilateral element mesh for surface with 2 mesh corners and a cut corner odd sum of elements gives a triangular element in cut corner small large cut corners yield different meshes SESAM Prefem Program version 7 1 01 JUN 2003 3 43 surface defined Even sum around surface 1 Only quadrilaterals normal mesh If odd sum around surface then triangular element in sharpest corner Demand triangular element in selected point sharp corner by TRIANGULAR ELEMENT Choose alternative transitions from triangular element to mesh in rest of surface numbers refer to illustrations V 2 TRIANGULAR PRE NONE 3 TRIANGULAR POST NONE A 4 TRIANGULAR BOTH NONE N 5 TRIANGULAR PRE ONE Eu va 6 TRIANGULAR POST ONE 7 TRIANGULAR PRE TWO TWO quad 8 TRIANGULAR POST TWO elements Mb Figure3 43 Alternatives for triangular element in corner SLE uo d Use command SET MESH EDGE RECTANGULAR surface line number of elements to get mesh as shown number of elements
130. File name excluding the mandatory file extension DXF for a DXF file and FEM for a SESAM Input Interface File Set control parameters for reading the DXF file Note that these settings are lost when a READ command has been executed Control whether the thickness information on the DXF file is to be read YES or not NO Note that on the DXF file the thick ness information is unique for each surface Default setting is NO Set the maximum angle for a surface corner to be defined as mesh corner Corners having a larger angle will be defined as not mesh corner The default value is 150 degrees Angle in degrees Control how the DXF polyline is interpreted and also whether to create Prefem surfaces from closed polylines These settings are reset after the READ command Control whether all closed 2D and 3D polylines shall be con verted to surfaces YES or not NO All line segments of a polyline will be converted to Prefem lines Default setting is NO Prefem 5 210 TO LINES TO NODELINE TO SPLINE INPUT INTERFACE FILE superelement number JOURNALLING MODE SESAM 01 JUN 2003 Program version 7 1 All line segments of a polyline will be converted to Prefem lines This is the default choice Polylines will be converted to Prefem node lines This is the default choice among TO LINES TO NODELINE and TO SPLINE Polylines will be converted to Prefem splines Note that this conversion is not necessarily shape p
131. I T DY T IX PDY DY 2T 32 IY IX 2 IZ IY IYZ 0 WXMIN 21X DY WYMIN 21Y DY Prefem SESAM APPENDIX B 16 01 JUN 2003 Program version 7 1 WZMIN 21Z DY SY DY DP 12 SZ SY SHARY 2IZ T SY SFY SHARZ 2IY T SZ SFZ SHCENY 0 SHCENZ 0 SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX B 17 B1 8 Un symmetrical I section B 1 8 1 Sectional Dimensions HZ Height BT Width of top flange BTA bl in Figure 5 44 Width of part of top flange along positive y axis TT Thickness of top flange TY Thickness of web BB Width of bottom flange BBA b2 in Figure 5 44 Width of part of bottom flange along positive y axis TB Thickness of bottom flange SFY Shear factor y direction SFZ Shear factor z direction A IRZ HZ Figure B 8 Un symmetrical I section B 1 8 2 Sectional Parameters Computed The expressions below for LX IY IZ WXMIN WYMIN WZMIN SHARY and SHARZ are taken from Ref 1 The expressions for SHCENY and SHCENZ are taken from Ref 3 Prefem SESAM APPENDIX B 18 01 JUN 2003 Program version 7 1 A HZ TB TT AREA BB TB BT TT A TY Y BB TR BBA BB 2 BT TT BTA BT 2 AREA Z BB TB 2 A TY TB A 2 BT TT HZ TT 2 AREA IX TT BT A BB 2 6TT 3 If TT TY and TT TB then WXMIN IX TT DNE es L1GT TT 4 TY BB TB 3 WXMIN IX MAX TT TY TB IY BEAL TY EHBODBRYAS UBTSTT HZ Z TI2
132. L Define an axial damper damp Axial damping coefficient TO GROUND Define a damper to ground n Number of degrees of freedom of the damping matrix cij Terms of the lower triangular part of the damping matrix The terms are given col umn by column i e cll c21 cnl c22 cn2 cnn see the matrix below The number of terms to enter p is a function of the number of degrees of freedom of the damping matrix n as follows p n n 2 The default value of the terms outside the diagonal is zero cll c21 c22 cnl cn2 cnn SESAM Prefem Program version 7 1 01 JUN 2003 5 185 PROPERTY MATERIAL material name ELASTIC ELASTIC young poiss rho damp alpha PURPOSE The command defines the data for an isotropic elastic material PARAMETERS young Young s modulus poiss Poisson s ratio rho Density damp Specific damping alpha Thermal expansion coefficient Prefem SESAM 5 186 01 JUN 2003 Program version 7 1 PROPERTY MATERIAL material name MASS MASS ONE NODED j n mi p PURPOSE The command defines the mass matrix of a mass element PARAMETERS ONE NODED Define a mass matrix for one node mass element n Number of degrees of freedom of the mass matrix mij Terms of the lower triangular part of the mass matrix The terms are given column by column i e m11 m21 mn1 m22 mn2 mnn see the matrix below The number
133. L THICKNESS 0 020000 SFY SHEAR FACTOR Y DIRECTION 1 000000 SFZ SHEAR FACTOR Z DIRECTION 1 000000 AREA CROSS SECTION AREA 0 038400 IX TORSIONAL MOMENT OF INERTIA ABOUT SHEAR CENTRE 0 002024 IY MOMENT OF INERTIA ABOUT Y AXIS 0 001932 IZ MOMENT OF INERTIA ABOUT Z AXIS 0 001023 IYZ PRODUCT OF INERTIA ABOUT Y AND Z AXES 0 000000 SESAM Prefem Program version 7 1 01 JUN 2003 5 123 WXMIN MIN TORSIONAL SECTION MODULUS ABOUT SHEAR CENTRE 0 008816 WYMIN MIN SECTION MODULUS ABOUT Y AXIS 0 006438 WZMIN MIN SECTION MODULUS ABOUT Z AXIS 0 005114 SHARY SHEAR AREA IN THE DIRECTION OF Y AXIS 0 013972 SHARZ SHEAR AREA IN THE DIRECTION OF Z AXIS 0 019872 SHCENY SHEAR CENTRE LOCATION FROM CENTROID Y COMPONENT 0 000000 SHCENZ SHEAR CENTRE LOCATION FROM CENTROID Z COMPONENT 0 000000 SY STATIC AREA MOMENT ABOUT Y AXIS 0 003888 SZ STATIC AREA MOMENT ABOUT Z AXIS 0 002928 CY CENTROID LOC FROM BOTTOM RIGHT CORNER Y COMPONENT 0 200000 CZ CENTROID LOC FROM BOTTOM RIGHT CORNER Z COMPONENT 0 300000 Print of loads The various types of loads are tabulated for the geometry for which they have been defined CONCENTRATED LOADS LOAD CASE NUMBER 1 GEOMERTY COORD TRANS Fx Fr Fy Fphi Fz Ftheta Mx Mr My Mphi Mz Mtheta P3 0 00000E 00 0 00000E 00 8 0000E 02 0 00000E 00 0 00000E 00 0 00000E 00 DISTRIBUTED LINE LOAD LOAD CASE NUMBER 2 LINE COORD TRANSF NAME SYSTEM NAME Fx Fr Fy Fphi Fz Ftheta POS L2 REA 9
134. L2 going through the points P1 through P4 L2 will be discreti sised into as many elements as there are line segments in this case 3 and there will be a node in each point DEFINE NODE LINE L2 P1 P2 P3 P4 Prefem SESAM 3 20 01 JUN 2003 Program version 7 1 PIX C28 P2 P3 P4 P1 E P2 Figure 3 14 Defining spline and node line An additional feature related to defining lines curves should be noted A line curve defined as one type e g a line may be changed into another type e g an arc The principle for changing type is to use the CHANGE command as if the line curve is already of the desired type The CHANGE command below changes a line into an arc by pretending that the line is already an arc Figure 3 15 illustrates the result This feature is convenient when the GENERATE command see Section 3 3 7 has been used to create a geometry consist ing of straight lines GENERATE in a cartesian coordinate system while in fact some of the lines are arcs or splines See Chapter 5 on CHANGE ARC INTERSECTION LINE for more information DEFINE LINE L1 P1 P2 4 CHANGE ARC L1 P1 P2 P0 4 P0 PO P1 Pl L14 Figure 3 15 Changing line to arc Defining Surfaces A surface is defined by an unlimited number of borderlines and curves forming a closed chain How to define various surfaces is exemplified below and illustrated in Figure 3 16 and Figure 3 17 Note Unless all borderlines and curves lie in a plane the shape of the inter
135. LUDED GEOMETRY OF ELEMENT element ALL POINTS INCLUDED ALL LINES INCLUDED ALL SURFACES INCLUDED ALL BODIES INCLUDED ELEMENT NUMBER SESAM Prefem Program version 7 1 01 JUN 2003 5 5 name of geometry EXCLUDE INCLUDE node NODE NUMBER END NODE GROUP nodel node2 nstep ALL NODES INCLUDED element ELEMENT NUMBER END ELEMENT GROUP eleml elem2 estep ALL ELEMENTS INCLUDED NEIGHBOUR ELEMENTS SPECIFIED ELEMENTS GEOMETRY OF ELEMENT element ALL POINTS INCLUDED ALL LINES INCLUDED ALL SURFACES INCLUDED ALL BODIES INCLUDED MATERIAL material name SECTION section name WITH l m THICKNESS lowthick highthick END PARAMETERS name of geometry Name of the geometry to select May also be a wild card selec tion see Section 3 9 3 and name of a pre defined set see Sec tion 3 9 4 NODE ELEMENT NUMBER Single nodes elements are selected terminate selection by END NODE ELEMENT GROUP A group of nodes elements are selected by giving first last and step ALL NODES ELEMENTS INCLUDED All nodes elements are selected GEOMETRY OF ELEMENT The geometry to which the given element belongs is selected the geometry name is logged on the command log file Prefem 5 6 ALL POINTS INCLUDED ALL LINES INCLUDED ALL SURFACES INCLUDED ALL BODIES INCLUDED and EXCLUDE INCLUDE NEIGHBOU
136. MMETRICAL I UNSYMMETRICAL I hz bt bl tt ty bb b2 tb sfy sfz PURPOSE The command defines an un symmetrical I cross section hz Figure 5 53 Un symmetrical I section PARAMETERS hz Height bt Width of top flange bl Width of part of top flange along positive local y axis tt Thickness of top flange ty Thickness of web bb Width of bottom flange b2 Width of part of bottom flange along positive local y axis tb Thickness of bottom flange sfy sfz Factors modifying the shear areas calculated by the program The modified shear areas are see the PRINT SECTION command for an explanation of the parame ters Prefem SESAM 5 202 01 JUN 2003 Program version 7 1 SHARY modified SHARY program sfy SHARZ modified SHARZ rogram sfz SESAM Prefem Program version 7 1 01 JUN 2003 5 203 PROPERTY THICKNESS THICKNESS select surfaces thickness PURPOSE The command specifies element thicknesses membrane and shell elements by assigning thicknesses to geometry surfaces PARAMETERS select surfaces Select surfaces See Section 5 1 on how to perform a selection thickness Thickness of the selected surfaces NOTES Rather than giving a constant value for the thickness a function describing a thickness variation may be given see Section 5 3 The function ONLY BETWEEN is less suitable for specifying thicknesses and should be avoi
137. N FACTOR com mand Draw the beam elements with their sections in a simplified manner and taking their eccentricities into account The display of eccentricities is enlarged by the SET GRAPHICS SIZE SYMBOLS SECTION FACTOR command For general section see the explanation for option OUTLINE SECTION Select labelling mode for element thickness Thickness of 2 D elements is shown by values Prefem 5 232 SYMBOLIC FILLED ELEMENT LAYERED ELEMENTS LAYERS LOCAL AXIS OUTLINE AREA OUTLINE SECTION SHELL ONLY SOLID AREA SESAM 01 JUN 2003 Program version 7 1 Thickness of 2 D elements is shown graphically In addition to the middle surface drawn with solid lines one side of the sur face is drawn with dotted lines the negative local z side and the other surface with broken lines the positive local z side The display of thickness is enlarged by the SET GRAPHICS SIZE SYMBOLS SECTION FACTOR command Switch ON or OFF filling of 2 D and 3 D elements with a col our Select display mode for layered elements Plate layers are drawn as simple shells with their eccentricities Stiffener layers are drawn as simple lines through the neutral axes Layered elements are drawn as simple shells only eccentrici ties are ignored Plate and stiffener layers are not explicitly drawn In addition a local axis is drawn in one of the nodes Plate layers are drawn as two surfaces one for the top and one for the botto
138. NE TRANSFORMATION or the PROPERTY TRANSFORMA TION commands See the note below Name of the transformation Deleting geometry will not automatically delete an element mesh already created for that geometry The mesh has to be deleted specifically The fact that the mesh remains after deleting the geometry cannot be taken advantage of in any way as properties related to the geometry are lost with the deletion of the geome try Do not delete a layered element type connected to a surface DELETE TRANSFORMATION has the same effect as the DELETE PROPERTY TRANSFORMATION command Prefem SESAM 5 94 01 JUN 2003 Program version 7 1 DELETE MESH ALL select geometry MESH PART select elements select nodes PURPOSE The command deletes the whole or parts of the FE mesh elements created PARAMETERS ALL Delete the whole mesh i e all elements of all types and all nodes PART Delete part of the mesh only See the note below select geometry Identify the mesh to delete by giving the name of the relevant geometry See Sec tion 5 1 on how to perform a selection select elements Select elements See Section 5 2 on how to perform a selection select nodes Select nodes See Section 5 2 on how to perform a selection SESAM Program version 7 1 01 JUN 2003 DELETE PROPERTY BOUNDARY select geometry INITIAL DISPLACEMENT select geometry INITIAL VELOCITY select geometry
139. NT See page 5 117 PROPERTY See page 5 126 RE COMPUTE See page 5 206 RE DISPLAY See page 5 207 READ See page 5 208 See page 5 23 Prefem 5 22 ROTATE SET WRITE ZOOM See page 5 211 See page 5 212 See page 5 262 See page 5 263 See page 5 264 01 JUN 2003 SESAM Program version 7 1 SESAM Prefem Program version 7 1 01 JUN 2003 5 23 ADD DISPLAY NODE ELEMENT SHAPE POINT select LINE ADD DISPLAY SURFACE BODY GEOMETRY FIND geometry name MESH LOAD load case load type PURPOSE The command adds element mesh geometry and load display to the current display without refreshing the screen Typically the mesh may be added to the geometry display shapes tools for modelling may be added and load display may be added to the mesh Also the command highlights a named geometric entity the FIND option This is used to locate a single point line surface or body in a geometry display PARAMETERS NODE Add selected nodes to the current display ELEMENT Add selected elements to the current display SHAPE Add selected shapes see the DEFINE SHAPE command to the current display A shape is in itself unlimited in space except for the spherical shape but it is dis played limited by the points defining it POINT Add selected points to the current display LINE Add selected lines to the current display SURFACE Add selected surfaces to the cur
140. NTS option to give a temperature for a selected line will also assign the temperature to the nodes on the selected line of adjoining shell and solid elements Yet another example Using the VALUE ON NEIGHBOURING ELEMENTS option to give a temperature for a selected body will only assign the temperature to the solid elements of that body PARAMETERS select geometry Select geometry Points cannot be selected See Section 5 1 on how to perform a selection ONE VALUE EACH NODE One value of the temperature difference is as signed to each node Can be used for any element type TWO VALUES ON SHELL Two values of the temperature difference are as signed to each node This option can be used for shell elements only The values given are the tem SESAM Prefem Program version 7 1 01 JUN 2003 5 169 perature differences on the inside and outside of the surface the inside given first VALUE ON NEIGHBOURING ELEMENTS See the explanation above temp diff Temperature difference tempdiffl tempdiff2 Temperature differences for the inside and outside surface of shell elements respectively NOTES Repetitive specification of temperature differences will override previous values For twenty node solid elements the mid side nodes will get the average of the corresponding corner nodes Prefem SESAM 5 170 01 JUN 2003 Program version 7 1 PROPERTY LOCAL COORDINATE BEAM YX PLANE ZX PLANE LOCAL COORDINATE BEAM X GLOB
141. NUMBEROF ELEMENTS and SET MAX ELEMENT LENGTH 2nd top Figure 5 26 Defining a body by DEFINE PRISM the effect of start and second points Prefem SESAM 5 78 01 JUN 2003 Program version 7 1 DEFINE ROUNDED CORNER CORNER ROUNDED CORNER linel line2 radius CORNER COMPLEMENT NONE PURPOSE The command rounds off a corner by creating an arc where two lines meet The arc will be tangential to both lines If the lines are borderlines of a surface then the surface is divided into two surfaces Either or none of these surfaces may be deleted See Figure 5 27 In case there is no surface the delete options decide which part of the corner lines to be deleted Note The two lines must be straight and meet in a point Note The program proposes a value for the radius being the length of the shortest of the two lines Note The lines and surface cannot have mesh PARAMETERS linel The first line line2 The second line radius The radius of the arc to create CORNER Delete the CORNER surface CORNER COMPLEMENT Delete the CORNER COMPLEMENT surface NONE Delete none of the surface line 1 line2 corner complement Deleted surface CORNER The orginal surface Deleted surface NONE Deleted surface CORNER COMPLEMENT Figure 5 27 Round off a corner by DEFINE ROUNDED CORNER SESAM Prefem Program version 7 1 01 JUN 2003 5 79 DEFINE SECTOR CORNER CORNER radius surface
142. O SECT NO NODE NUMBER 1 BEAS 2 1 2 2 BEAS 2 2 3 3 BEAS 2 3 4 4 BEAS 2 4 5 5 BEAS 1 6 7 6 BEAS 1 7 8 7 BEAS 1 8 9 8 BEAS 1 9 10 9 BEAS 1 10 11 10 BEAS 1 TI 12 11 BEAS 1 12 13 12 BEAS 1 13 14 13 BEAS 1 14 15 14 FQUS 5 00E 02 15 16 25 14 15 FQUS 5 00E 02 16 17 26 25 16 FQUS 5 00E 02 17 18 27 26 17 FQUS 5 00E 02 18 19 28 27 etc SESAM Prefem Program version 7 1 01 JUN 2003 5 125 Print of element local coordinate systems The table informs about the local coordinate systems of all elements The cosines relative to the coordinate system of the superelement is given for each of the local axes EXT LOCAL X LOCAL Y LOCAL Z EL ND GX GY GZ GX GY GZ GX GY GZ REM 1 1 0 316 0 949 0 949 0 316 1 000 SPEC 2 1 0 316 0 949 0 949 0 316 1 000 SPEC 3 1 0 316 0 949 0 949 0 316 1 000 SPEC 4 1 0 316 0 949 0 949 0 316 1 000 SPEC BT F000 1 000 1 000 SPEC 6 1 1 000 1 000 1 000 SPEC 7 1 1 000 1 000 1 000 SPEC 8 1 1 000 1 000 1 000 SPEC Jio X 1000 1 000 1 000 SPEC TO 50 275 205962 0 962 0 275 1 000 SPEC 11 1 0 093 0 996 0 996 0 093 1 000 SPEC 12 1 0 093 0 996 0 996 0 093 1 000 SPEC 13 1 0 275 0 962 0 962 0 275 1 000 SPEC 14 NONE 15 NONE 16 NONE etc Print of element eccentricities The table provides details on eccentricities offsets for the elements OFFSETS IN SUPERELEMENT S COORDINATE SYSTEM FROM NODE TO ELEMENT EXT INT ECCENTRICITIES AT ODD NODES ECCENTRICITIES AT EVEN NODES
143. OMENT c cccccccccesssscccsesseccessesessssesccsessseeesssseeessnes 5 158 PROPERTY LOAD load case NORMAL PRESSURE eee nennen 5 159 PROPERTY LOAD load case PART LINE eene eene nemen nennen enne enne 5 160 PROPERTY LOAD load case PRESCRIBED ACCELERATION ceceeee 5 163 PROPERTY LOAD load case PRESCRIBED DISPLACEMENT ee 5 165 PROPERTY LOAD load case RIGID BODY ACCELERATION ce 5 166 PROPERTY LOAD load case RIGID BODY VELOTCITY eene 5 167 PROPERTY LOAD load case TEMPERATURE eee ern nenennene ne ener en nne 5 168 PROPERTY LOCAL COORDINATE BEAM eee eee eene nenne nnne nne enar senes 5 170 PROPERTY LOCAL COORDINATE SURFACE eeeeeeeeene eee een n nne enne eene nnns 5 173 PROPERTY MATERIAL 11 eren een nen n nne eR nnne nne en nne en tene se tenens ai 5 175 PROPERTY MATERIAL material name ANISOTROPIC eere 5 176 PROPERTY MATERIAL material name ANISOTROPIC 2D ELEMENT nmm 5 177 PROPERTY MATERIAL material name ANISOTROPIC 3D SHELL ELEMENT 5 179 PROPERTY MATERIAL material name ANISOTROPIC SOLID ELEMENT 5 182 PROPERTY MATERIAL material name DAMPBER eee eeenenennnnnn nis 5 184 PROPERTY MATERIAL material name ELASTIC ssseeeeeeee eee 5 185 PROPERTY MATERIAL material name MASS sese eene e eene eere 5 186
144. ONE Delete none of the surface Prefem SESAM 5 80 01 JUN 2003 Program version 7 1 surface centre pnt The orginal surfaces Cutting the first surface Cutting all 4 surfaces and deleting the corners Figure 5 28 Create a hole by DEFINE SECTOR CORNER centre pnt The line to cut by the arc doesn t connect to the centre point The line to cut must be stralght Figure 5 29 Examples where DEFINE SECTOR CORNER cannot be used SESAM Prefem Programverson7 01JUNJ3 8 amp 8 DEFINE SET set name INTERSECTION WITH ALL BODIES select bodies ELEMENTS select elements SUBTRACT BY LINES select lines T SET name NODES select nodes POINTS select points UNIONE SPRING DAMPER select spring damp SURFACES select surfaces END END PURPOSE The command defines a set a named selection of geometry elements or nodes A set may be referred to in commands where selecting geometry elements or nodes is required The DEFINE SET command defines a new set while the CHANGE SET command changes an existing set The command syntaxes of these two commands are identical and based on standard set operators Initially i e after giving the command DEFINE SET and entering a name of the set the set is empty The first operation to do will therefore be to add to the set by selecting the UNION WITH command Thereafter repetitive set operations m
145. OPERTY LOAD command Super the d o f is a super d o f Boundary conditions may be given for any geometrical entity i e bodies surfaces lines and points A boundary condition given for a body will also apply to the surfaces lines and points of which the body is composed The same is the case for a surface and a line the boundary condition given will always apply to the lower level geometrical entities of which the specified geometry is composed A specification of boundary condition will replace any previous specification for the same geometry This allows a point and a line connected to it easily to be given different boundary conditions Simply give the boundary condition for the line first and thereafter for the point Giving the boundary condition for the line last will overrule any previously given boundary condition for the point SESAM Prefem Program version 7 1 01 JUN 2003 3 51 Boundary conditions may be specified in the cartesian coordinate system of the model in a rotated cartesian coordinate system or in cylindrical and spherical coordinate systems 3 5 8 Linear Dependency Linear dependency is forcing the displacement of a degree of freedom d o f of a node to be a linear func tion of the displacement of one or several other d o f The PROPERTY LINEAR DEPENDENCY com mand is used for this purpose There are a few alternative ways of defining linear dependencies e TWO POINT DEPENDENCY defines linear dependen
146. Only given when a single line has been select relative length first elem Relative element length of the first element i e the element closest to the starting point relative length last elem Relative element length of the last element GIVEN RELATIVE The relative element edge lengths are given individually relative length of elem Relative element length given as a positive number for each el ement on the line s starting at the starting point The number of values to give must correspond to the number of elements for the lines in question SESAM Prefem Program version 7 1 01 JUN 2003 5 221 NOTES If the GIVEN RELATIVE option has been used and the number of elements for the lines in question is thereafter increased then the extra elements will have no relative length value This involves that element lengths will be zero i e the elements element edges will collapse To remedy this situation a new SET ELEMENT LENGTH RATIO command must be given To avoid such a situation use the EQUALLY SPACED or ARITHMETRIC SEQUENCE options rather than the GIVEN RELATIVE option On the other hand if the number of elements for lines is decreased after giving relative lengths of all ele ments for lines then the superfluous length values will be neglected Prefem 5 222 01 JUN 2003 SET ELEMENT TYPE LINE element type ELEMENT TYPE SURFACE select geometry NONE BODY PURPOSE SESAM Program version 7
147. P EN sr teec e pot eoi ehe etc et ada aged cate Sed deka Le Ob Saeed bnt tr betae pe 5 19 JABS SIGN I MAX MEN 9 DM SOR TE idit roc pen photons ei theta oss ai 5 20 Detailed Description of Commands sse eene enne 5 2 ADD DISPLAY s t detegit teen tepida ein 5 23 CHANGE etre tio oet RU te SD Aided d DES N 5 25 CHANGE ARC INTERSECTION LINE SPLINE NODE LINE eee 5 27 CHANGE ELEMENT ATTRIBUTE e itnn an an tinet enne tte sns th a instet enses eth nn 5 29 CHANGE MESH tete e a SOIN ERO D ER RUE CREER HERE 5 31 CHANGE NAME vaavin ente etit i e ee ha n dest ris rp eoa gu eceusden en bed tete eene 5 33 CHANGE NODE eee ERR QI I NN eie ee etes 5 34 CHANGE NORMAL OF SURFACE ROTATION OF SURFACE eee 5 35 CHANGE POINT terea edt a c steep diete te ee i tee RP ERREUR 5 37 CHANGE PROPERTY LOAD load case TO MASS sse nennen 5 38 CHECK 5o eive orte tie eme ec Die dis tiliue eeu Naa NU CN Can aes 5 40 CHECK CLUSTERED NODES 4e iie hace reta eta enne RN ee eva diaeta eee ions 5 41 CHECK CLUSTERED POINT Siirron roter toto p ERRARE VE EET caer 5 42 CHECK ELEMENT SHAPE e a aa tent etn tn stes ths tts these etse E a et senses th Ea senta 5 43 CHECK MESH TOPOL OGY e rettet eta x RO GER RE ERR EP E a n 5 45 CHECK NON REGULAR NODBES 1 s tore aaaea ea EE tne to instan staat ses en seines nn 5 46 CONNECT 5k rtr ttt e Re eee Dr Hte RC ge etre bes aee gie en ete
148. P70 The PostScript plot format File extension is PS Prefem SESAM 5 252 01 JUN 2003 Program version 7 1 SESAM NEUTRAL A plot format of the SESAM system File extension is PLO WINDOWS PRINTER The plot will be sent directly to the on line printer No plot file will be generated This is the default format on PC ORIENTATION Set the page orientation Valid for PostScript format only PORTRAIT Portrait orientation This is default PAGE SIZE Set the plot page size All sizes are not available for all plot formats For SESAM NEUTRAL this setting is irrelevant as the page size is set within the PLOT com mand Valid for PostScript format only A4 European standard page sizes paper formats See explanation for the PLOT com mand SESAM Prefem Program version 7 1 01 JUN 2003 5 253 SET PREFIX NAME ON prefix PREFIX NAME OFF PURPOSE The command sets a prefix for geometry names i e a string that is put in front of subsequently generated geometry names The command allows setting various prefixes during the modelling and in this way ease later identification and selection by wild card of geometry The structure of the geometry names resulting from this command is prefix geometry type number where geometry type is P for points L for lines S for surfaces B for bodies number is a number incremented by the program PARAMETERS prefix The prefix string NOTES Note that a g
149. PROPERTY MATERIAL material name SPRING eene ennemis 5 187 PROPERTY POINT M ASS ined ttr E tete tne eet ter eese e 5 188 PROPERTY SEGIION 5 n neereicetreste pv RIETI edet e ed e V RAMS 5 189 PROPERTY SECTION section name BAR rene Irene enne nenne ennt eser eterni 5 191 PROPERTY SECTION section name BOX 0 ccccccccccesscccessscececssceceesssececssscecessseesensesescenseaess 5 192 PROPERTY SECTION section name CHANNEL eese eene nnne nennen eres 5 193 PROPERTY SECTION section name DOUBLE BOTTOM seeeeeeeenene eee mene enenn 5 194 PROPERTY SECTION section name GENERAL eere eene nnne ennt 5 196 PROPERTY SECTION section name Lorien ar E N nnne eene nenne senten eene nn nnn 5 198 PROPERTY SECTION section name L sssseseseseeeeeen eene rennen nennen nennen enne tense nnne en 5 199 PROPERTY SECTION section name PIPE sseeseseeeeeeeeene nennen nennen een nnne an 5 200 PROPERTY SECTION section name UNSYMMETRICAL I eere 5 201 PROPERTY THICKNESS oueres ina i TRATAR esie e GT LOT HD D RE PLE PES 5 203 PROPERTY TRANSFORMATION 0 0 0 ccccccccccssscceessscecessscecesssceceesseeesesseececsssseecessseeeesssaesenseaess 5 204 RE GOMPUEIEE 7 iie ttt detected tete a dtt DE eta Tih a eis 5 206 RE DISPI AY dnd eine p DE e EE oe a e ee ot e ved ede ee e odi 5 207 h nwbp U ER 5 208 U5 39 B72 BE iet teie t eui noit NOR
150. Print the transformations in un decoded form i e print the transformation matrices Information printed on the screen is broken into a certain number of lines in order not to fill more than a sin gle window at a time The user is requested to CONTINUE or END the printing after each screen fill As the CONTINUE alternative is the default choice a semicolon accepting all subsequent default values involves printing all information The PRINT ALL command will always generate a print file All other PRINT commands will by default direct the print to the screen The SET PRINT DESTINATION command may change this so that all print goes to a print file Some typical print tables are presented below with explanations of their contents Prefem SESAM 5 120 01 JUN 2003 Program version 7 1 Print of point coordinates The point coordinates are tabulated POINT NAME X x Z Pl 0 00000E 00 0 00000E 00 0 00000E 00 p2 1 00000E 01 0 00000E 00 0 00000E 00 P3 1 20000E 01 6 00000E 00 0 00000E 00 P4 8 00000E 00 7 00000E 00 0 00000E 00 P5 4 00000E 00 7 00000E 00 0 00000E 00 P6 0 00000E 00 7 00000E 00 0 00000E 00 PCENTRE 9 00000E 00 3 50000E 00 0 00000E 00 Print of point properties The table contains point masses There are two lines for each point the first line is translational masses while the second is rotational masses The column BOUND contains a six character boundary condition code one character for each of the six degrees of
151. R ELEMENT SPECIFIED ELEMENT WITH MATERIAL SECTION THICKNESS 5 3 Functions SESAM 01 JUN 2003 Program version 7 1 All points of the geometry model are selected All lines of the geometry model are selected All surfaces of the geometry model are selected All bodies of the geometry model are selected Parentheses enable giving several entries Remember entering a space on both sides of the parentheses Exclude geometry names from geometry already selected Include geometry names this is relevant after an EXCLUDE command in order to counteract the exclusion This is a switch that implies selection also of the neighbouring solid elements of a surface selected For example the command NEIGHBOUR ELEMENT S1 also selects solid elements being neighbours to S1 whereas the command S1 only se lects shell membrane beam elements within S1 This is a switch that counteracts the NEIGHBOUR ELEMENT switch I e it switches back to the normal or default selection mode Of the nodes elements currently selected within the current command only those with the appropriate characteristics are selected The given material name is the criterion for selection The given section name is the criterion for selection The lower and upper limit for thickness is the criterion for se lection Functions cannot have been used for specification of the thickness for this option to work Surface thickness and loads surface press
152. SESAM APPENDIX B 4 01 JUN 2003 Program version 7 1 IY BB HZ 12 HZ BE HZ 2 HY 24 HZ 36 A HZ2HZ 3 Hy WYMIN IY MAX H D IZ HZ BB 12 HZ A 18 A HZ BB 2 4 3 WZMIN 21Z MAX BT BB SY BB H 2 B BB 2 H 3 SZ HZ BB 8 A BB 4 4 6 SHARY IZ HZ SFY SZ SHARZ 21Y B SFZ SY SHCENY 0 IYZ 0 CA 0 141 CB 0 208 If HZ BM then j IX CA HZ WXMIN CB HZ ll CN BM HZ CA 1 0 63 CN 0 052 CN 3 Else if HZ lt BM then 4 CB CA 1 0 63 1 CN ll IX CA BM HZ WXMIN CB BM HZ CN HZ BM CA 1 0 63 CN 0 052 CN 3 Else CB CA 1 0 63 1 CN IX CA HZ BM WXMIN CB HZ BM SHCENZ 0 354HZ BT BB BT BB HZ 2 H CY BB 2 CZ H SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX B 5 B1 2 Box section B 1 2 1 Sectional Dimensions HZ Height BY Width TT Thickness of top flange TY Thickness of webs vertical walls TB Thickness of bottom flange SFY Shear factor y direction SFZ Shear factor z direction Figure B 2 Box section B 1 2 2 Sectional Parameters Computed The expressions below for LX IY IZ WXMIN WYMIN WZMIN SHARY SHARZ and SHCENY are taken from Ref 1 The expression for SHCENZ is taken from Ref 2 A TB 2 B HZ TB TT 2 C HZ TT 2 D HZ TB TT Prefem SESAM APPENDIX B 6 01 JUN 2003 Program version 7 1 E BY TB F BY TT G TY D AREA E F 2G H
153. STEM coord name SPHERICAL start XyZ Z axiS xyz r axis Xyz PURPOSE The command defines a coordinate system Loads and boundary conditions normal to spheres and cylinders may easily be defined by referring to previously defined coordinate systems Using a transformation com bined with a cylindrical coordinate system also allows specification of loads and boundary conditions nor mal to a cone Coordinates of points may be specified in cylindrical or spherical coordinate systems A coordinate system is identified by its type i e cylindrical or spherical and a transformation of the carte sian coordinate system of the model It is defined by specifying its origin defining its z axis cylindrical or pole axis spherical and defining the 0 plane which determines the r axis PARAMETERS coord name User given name of the coordinate system CYLINDRICAL A cylindrical coordinate system is defined SPHERICAL A spherical coordinate system is defined start Xyz Cartesian coordinates of the origin of the coordinate system Z axis XyZ Cartesian coordinates of a point defining the z or pole axis of the coordinate sys tem I aXls XyZ Cartesian coordinates of a point defining the 0 plane which determines the r axis NOTES A coordinate system cannot be changed or deleted Coordinate systems defined are printed on the screen by the PRINT TRANSFORMATION command SESAM Prefem Program version 7 1
154. Section 4 1 8 or you need to use the command WRITE in order to produce the Input Interface File the T file In such case you also need to run Bpopt man ually after exiting Prefem i e if you need to optimise the internal node numbering 2 14 Interaction with other SESAM Programs All model characteristics featured by Prefem are not necessarily accepted by a particular analysis program The Sestra linear analysis program will accept most model data created by Prefem When creating a model for the non linear analysis program Advance you should make sure the model is consistent with the analysis program SESAM Prefem Program version 7 1 01 JUN 2003 3 1 3 USER S GUIDE TO PREFEM The purpose of Prefem is to create a FE model for structural analysis or a panel model for hydrodynamic analysis This is done by first defining a geometry model and assigning element discretisation FE mesh data to this model Based on this information the FE model is created automatically Secondly various prop erties like beam cross sections and eccentricities offsets surface thicknesses material data and boundary conditions are given and assigned to the appropriate parts of the geometry model Finally the loads are defined and assigned to the geometry model All properties and loads are automatically transferred to the FE model The output from Prefem is the Input Interface File see Section 2 13 containing the FE model This user s guide explains how
155. T SHAPE SPLINE SPRING CHANGE SUPERELEMENT SURFACE TRANSFORMATION a This option is presently inactive b This option is presently inactive PURPOSE The command changes parameters or values of previously defined geometry properties and other data Most of the commands have the same syntax and corresponding interpretation as the commands defining the data Therefore rather than describing these commands in detail here reference is made to the corre sponding DEFINE or PROPERTY commands Prefem SESAM 5 26 01 JUN 2003 Program version 7 1 However some CHANGE commands demand special explanations these are found on the following pages These are CHANGE ARC INTERSECTION LINE SPLINE NODE LINE CHANGE ELEMENT ATTRIBUTE CHANGE MESH CHANGE NAME CHANGE NODE CHANGE NORMAL OF SURFACE ROTATION OF SURFACE CHANGE POINT CHANGE PROPERTY LOAD load case TO MASS NOTES If changes are made to loads by the CHANGE PROPERTY LOAD command then use the RE COMPUTE LOADS command to redistribute the loads otherwise an ADD DISPLAY LOAD command will not give correct result This re computation will automatically be performed when producing the Input Interface File Changes made to a transformation using the CHANGE TRANSFORMATION command will be added to its current definition Such a change will thus have the same effect as if the da
156. TS OUTSIDE PLANE STRAIN PLANE STRESS PLOT PREFIX NAME PRINT PROJECTION TASK TOLERANCE WRITE MODE SET PURPOSE The command defines and sets various parameters PARAMETERS COMMAND INPUT FILE Set name of the command input file Use the command to read commands You may however find it more convenient to SESAM Program version 7 1 DEFAULT ELEMENT LENGTH RATIO ELEMENT TYPE GRAPHICS INSIDE JOURNALLING MAX ELEMENT LENGTH MESH MESH CORNER MESH PARAMETERS NAMING NOT MESH CORNER NUMBEROF ELEMENTS OUTSIDE PLANE STRAIN PLANE STRESS PLOT PREFIX NAME PRINT Prefem 01 JUN 2003 5 213 specify a command input file when starting Prefem from Man ager Set various default conditions e g which property type of el ement number of elements material section thickness etc to automatically assign to subsequently created geometry Set length of elements element edges see Section 3 4 1 Set types of element to be created for geometry lines surfaces and bodies see Section 2 5 for information on element types Set various parameters controlling the graphic presentation Define inside of surfaces for the benefit of pressure load appli cation see Section 3 12 3 Switch on logging in command log file see Chapter 4 of print and graphics commands Set maximum element length for lines see Section
157. TY LINEAR DEPENDENCY TWO POINT DEPENDENCY TWO POINT DEPENDENCY dep point beta BY RELATIVE DISTANCE indep pointl indep node2 PURPOSE The command defines linear dependencies between a node and two other independent nodes The nodes are selected by referring to geometry points All d o f s of the dependent node are made linearly dependent of the corresponding d o f s of two independ ent nodes The displacement of the dependent d o f s will be Tdep Tindep1 B Tindep2 1 B where p is a dependency factor either given by the user or computed by the program based on the projection of the dependent node onto the line between the two independent nodes See Figure 5 39 Normally the two point dependency is used when the dependent and the two independent nodes lie on a straight line PARAMETERS dep point Name of the dependent point indep pointl Name of the first independent point indep point2 Name of the second independent point beta Linear dependency factor BY RELATIVE DISTANCE The linear dependency factor is calculated by the program as explained in Figure 5 39 Prefem 5 144 01 JUN 2003 PROPERTY LOAD LOAD load case BEAM CONCENTRATED COMPONENT PRESSURE CONCENTRATED GRAVITY HYDRO PRESSURE LINE LOAD LINE MOMENT NORMAL PRESSURE PART LINE PRESCRIBED ACCELERATION PRESCRIBED DISPLACEMENT RIGID BO
158. Y BY 2 YY A TY 12 A TY Y TY 2 IYZ 0 WYMIN 21Y HZ WZMIN IZ MAX BY Y Y SY BY TZ TZ A 2 TY A 78 SZ TZ BY Y SHARY IZ SZ QTZ SFY SHARZ IY SY TY SFZ If TZ TY then Q B TY 2 HZ TZ TZ AIY Else Q BY TY 2 TZ BY TY 2 TZ HZ TZ TY 3 SHCENY Y TY 2 Q If web located in positive y then CY BY Y SHCENY Y TY 2 Q Else CY Y CZ Z SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX B 9 B1 4 Double bottom section B 1 4 1 Sectional Dimensions HZ Height TY Thickness of web TB Thickness of bottom plate TT Thickness of top plate BY Effective width of plates SFY Shear factor y direction SFZ Shear factor z direction Figure B 4 Double bottom section B 1 4 2 Sectional Parameters Computed The calculation procedure for the double bottom section is the same as for the I section for computation of all parameters except LY and WXMIN In the formulae below ZXI is the ZX for the I section IX IXI HZ BY Y TB 1 TT WXMIN IX MAX TT TY TB Prefem SESAM APPENDIX B 10 01 JUN 2003 Program version 7 1 B1 5 I or H section B 1 5 1 Sectional Dimensions HZ Height BT Width of top flange TT Thickness of top flange TY Thickness of web BB Width of bottom flange TB Thickness of bottom flange SFY Shear factor y direction SFZ Shear factor z direction Figure B 5 I or H section B 1 5 2 Sectional Parameters Computed The expressi
159. Y TB BB Z TB 2 TY A TB 4 2 Z IZ TT BT A TY TB BB 12 TT BT BT 2 BTA Y BB TB BB 2 BBA Y TY A Y IYZ BT TT BD TT 2 BT 2 BTA Y A TY Y TB A 2 Z BB TB TB 2 Z BB 2 BBA Y WYMIN IY MAX HZ Z Z WZMIN IZ MAX MAX BTA BBA Y MAX BT BTA BB BBA Y BC abs Y TY 2 BD HZ TT Z BE BTA Y BF BBA Y If BC 0 then SZ TT BE 2 TB BF 2 A BC 72 Else if Y lt 0 then SZ TT BE TB BF 2 A TY BC Else SZ TT BE TB BF 2 SY BT TT BD TT 2 TY BD 72 SHARY IZ SZ TB TT SFY SHARZ IY SY TY SFZ RZ HZ TT TBy 2 SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX B 19 FL BTA abs Y If Y lt 0 then GL BBA abs Y l p BTA abs Y GL BBA abs Y FR BT FL GR BB GL CT BD TT 2 CB Z TB 2 BTAR BT BTA BBAR BB BBA BG BBA BBAR 3 GL BBA GR BBAR SHCENY Y 0 5RZ TB IYZ BG IZ CB BBA BBAR Y IZ IYZ BH BTA BTAR 3 FL BTA FR BTAR CY Y BB BBA CZ Z Prefem SESAM APPENDIX B 20 01 JUN 2003 Program version 7 1 B2 Units A SESAM analysis is based on a set of consistent units The units to use must be determined before com mencing the modelling and these units must be adhered to throughout the analysis project i e in all SESAM programs employed The basis for determining a set of consistent units and some examples are given below The f
160. YX PLANE The local y x plane is to be defined ZX PLANE The local z x plane is to be defined X GLOBAL INFINITY The guiding point is positioned infinitely far out along the pos itive global X axis X GLOBAL INFINITY The guiding point is positioned infinitely far out along the neg ative global X axis Y GLOBAL INFINITY The guiding point is positioned infinitely far out along the pos itive global Y axis Y GLOBAL INFINITY The guiding point is positioned infinitely far out along the neg ative global Y axis Z GLOBAL INFINITY The guiding point is positioned infinitely far out along the pos itive global Z axis Z GLOBAL INFINITY The guiding point is positioned infinitely far out along the neg ative global Z axis GUIDING POINT DIRECTION The guiding point is positioned at a given vector away from end 1 of the element FROM FIXED POINT The guiding point is a fixed point and the positive direction of the local y or z axis whichever is relevant is from the fixed point and towards end 1 of the element In contrast with the oth er alternatives this option therefore involves that the guiding point is positioned on the negative y z side TOWARDS FIXED POINT The guiding point is a fixed point and the positive direction of the local y or z axis whichever is relevant is from end 1 of the element and towards the fixed point Prefem SESAM 5 172 01 JUN 2003 Program version 7 1 XYZ If GUIDING POINT DIRECTION Vector given in the ca
161. Z After selecting the four deck surfaces and choosing the global cartesian coordinate system for the load give zero for the X and Y components and 500 for the Z component Following the Z value give END meaning that the load is not going to be complex we are making a model for a static analysis and not for a frequency domain analysis Conclude the load definition by specifying where on the plate the load shall apply the MIDDLE SURFACE this choice has conse quence for curved 6 and 8 node elements only Give END to leave definition of load case 1 Load case number 2 is a NORMAL PRESSURE meaning that only one component which is always normal to the plate elements is given Select all skin surfaces Being a hydrostatic pressure with the water surface at the level of the top of the ship side Z 48 the load varies linearly in the vertical direction zero pressure at Z 48 380 at Z 10 where the bilge starts and 480 at Z 0 ship bottom This variation is easily defined by selecting the option LINEAR 2POINTS VARYING and giving the SESAM Prefem Program version 7 1 01 JUN 2003 3 15 appropriate values for any two points on a vertical line For example Click the point in 0 0 48 and give the pressure value 0 then click the point in 0 0 10 and give the value 380 linear extrapolation outside the two selected points Then give END meaning that the load is not going to be complex Conclude the load definition by specifying where on the plate the
162. a background job rather than as an interactive session Here is a proposal for how to do this This proposal is not relevant for executing Prefem through Manager in which case background execution is controlled by Manager Execute Prefem in the background as follows Prepare a file e g a revision of a previous command log file containing the input data let the name of the file be FILE_IN JNL SESAM Program version 7 1 Prefem 01 JUN 2003 4 7 Prepare a file with the following contents the entries FILE and FILE IN are example file names D D FILE NEW SET COMMAND INPUT FILE FILE IN ALL EXIT The two apostrophes in the first and fourth lines enclose a blank space it may also be a blank line to specify void prefixes If a prefix is given in the fourth line e g PREFIX it will precede the given com mand input file name requiring the full name of the file containing the input data to be PREFIXFILE IN JNL Start Prefem as a background job with the file above as input file 4 1 8 Command Line Arguments It is possible to specify command line arguments when starting Prefem A command line argument will influence the program execution in various ways On Unix systems the command line arguments are simply added to the command for starting the program prompt prefem NOHEADER STAT OLD INT LINE C F TEST IN JNL FORCED EXIT The command line arguments are PREFIX text NAME text STATUS text INT
163. acting on the inside of the surfaces Pressure is acting on the outside of the surfaces Pressure is acting in the middle surface The pressure is applied to the inside of the specified layer The pressure is applied to the middle of the specified layer The pressure is applied to the outside of the specified layer Layer number see Section 3 10 2 This load case shall be applied both to the panel model for hydrodynamic analysis and the FE model for structural analysis SESAM Prefem Program version 7 1 01 JUN 2003 5 155 PROPERTY LOAD load case LINE LOAD LINE LOAD select lines GLOBAL TRANSFORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam INSIDE SURFACE SHELL ELEMENT ifx ify ifz MIDDLE SURFACE SHELL ELEMENT OUTSIDE SURFACE SHELL ELEMENT fx fy fz BEAM ELEMENTS END MEMBRANE ELEMENT MIDDLE LAYER LAYERED ELEMENT layer PURPOSE The command defines line distributed loads forces acting on lines The line load must be defined to be acting on beam elements membrane elements or shell elements If the load is defined to be acting on say a beam element but only shell elements are present then no load will apply If e g both beam and shell elements are present then the load may be applied to either of them assuming the inside outside of the shell elements and beam eccentricities have no consequence Conce
164. ad is identified by referring to the appropriate geometry It is therefore the extent of this geometry and not the function see Section 3 7 that limits the application of the load This is illustrated in Example 3 4 Example 3 4 Defining a Constant Pressure Load A constant pressure on the surface AU11 is defined by Define load 1 PROPERTY LOAD 1 Load type NORMAL PRESSURE Reference to geometry Prefem SESAM 3 54 01 JUN 2003 Program version 7 1 AU11 Load value END means no complex load 200 END oe Where to apply the load MIDDLE SURFACE The load value 200 is in essence a constant function unlimited in space Figure 3 50 Extent of load is limited by reference to geometry For the LINE LOAD PART LINE NORMAL PRESSURE and COMPONENT PRESSURE load types the concept of inside and outside of surfaces is of relevance see Section 3 12 3 Loads can be changed by the CHANGE PROPERTY LOAD command PROPERTY CHANGE is an equivalent command The change is performed only for the geometry that actually has loads of the given type in the given load case The change concerns the first specified load on each geometry of correct type DELETE PROPERTY LOAD removes the load definition from the model All loads in the given load case of the given load type and for the given geometry are deleted If changes are made to the loads by the CHANGE PROPERTY LOAD or DELETE PROPERTY LOAD commands or the position of nodes are
165. all switched on depressed See information on these buttons below Note that if the Direct access button Info is depressed then geometry cannot be selected by clicking See information on the Info button below Command menu The at any time allowable commands plus default values for numerical data are listed here as buttons Commands and values are selected by clicking the left mouse button LMB Slanted text signifies default choices that are accepted by either Hitting the Return key e Clicking either of the Direct access buttons semicolon and double slash The former accepts all subsequent default values see Section 4 1 4 while the latter accepts a single default value i e the one shown in slanted font Shortcut commands These provide one click access to commonly used compound commands A Shortcut command is logged as its equivalent full standard commands The Shortcut commands are sorted in four groups as follows Present Col Thi Colour shell membrane elements according to their thicknesses Col Mat Colour elements according to their material type Wirefram Switch off colouring of elements i e revert the actions of Col Thi and Col Mat Hidden Toggle switch on and off hidden display removing hidden lines Shrunken Toggle shrunken display with factor 0 7 Display Geometry Display all geometry Surface Display selected surfaces the surfa
166. all the surfaces will then be selected The element selection of the command is logged in terms of screen coordinates of the graphic rubberband or polygon and not in terms of element numbers This involves that when the log file is used as command input file in a new session the elements in the same positions within the same surfaces will be selected even when the element numbers have changed due to a different meshing sequence or a new meshing algorithm Note Referring to the paragraph above When a log file is used as command input file in a new ses sion and a different mesh is created for the area in question then the new elements may and may not fall within the graphically selected area thereby producing unexpected results PARAMETERS select geometry Select geometry containing elements to be changed See Section 5 1 on how to per form a selection graphic select elem Select elements to be changed by dragging a rubberband completely enclosing them Prefem 5 30 MATERIAL material name THICKNESS thickness SESAM 01 JUN 2003 Program version 7 1 The material of the elements is to be changed The new material name which must have been defined The thickness of the elements is to be changed The new thickness SESAM Prefem Program version 7 1 01 JUN 2003 5 31 CHANGE MESH MESH select surfaces DISPLAY select and move node PURPOSE The command changes the mesh by moving a selected
167. ange the FE mesh e g increase or decrease the element density without having to re enter the proper ties see Figure 2 2 The geometry can also be changed without re defining the properties If for example a surface with pressure load is deleted the load will automatically disappear On the other hand if only the shape of the surface is changed the load will remain N CA 7H an V NS IN CHO JH pi MES vis ONT EIR a IES N NV yas lY Wh i i avi Vl x oll E Y LN SSH Load normal pressure created then mesh deleted and new mesh created load prevails Figure 2 2 Properties assigned to geometry model allows changing mesh without re entering data Throughout the modelling the user will therefore basically only work with the geometry define the geom etry delete and change it refer to it when defining properties and display it The FE model being the objec tive of the modelling is a concern of the program the user will basically never have to refer directly to it he will however display the FE model for verification purposes This approach is logical as it brings the mod elling work close to the definition of the structure i e the drawings or a CAD model The approach is also efficient as the time consuming task of defining elements and nodal coordinates is left to the program Effi ciency is also gained as quick and easy re meshi
168. angular general anisotropic elasticity matrix 5 4 d4l d42 d43 d44 d51 d52 d53 d54 d55 NOTES An orthotropic material is defined by taking advantage of the fact that it is a special case of the anisotropic material To define an orthotropic material in its principal axes the lower triangular part of the general aniso tropic elasticity matrix should have zero values for some of the terms dll d21 d22 0 0 d33 5 5 0 0 0 d44 o 0 0 0 ds5 Projection of the Q vector onto the element plane Three orthogonal princip axes of orthotropic material Cartesian coordinate system of the model X X Figure 5 44 Shell element with orthotropic material properties The elasticity matrix of an orthotropic material expressed in terms of the Young s and shear moduli and Poisson s ratio is given below The stress strain relationship o D is SESAM Prefem Program version 7 1 01 JUN 2003 5 181 o Ej VE 0 0 i o i Vik E 0 0 5 In TOS 0 0 Gy I1 VpV3 0 0 Yi2 5 6 T23 0 0 0 Gy3 1 Vi5V3 0 Yo3 T31 0 0 0 0 G3i 1 V12V21 Ys where Oj and amp are the strain stress and Young s modulus respectively in the direction of axis no i vij is the coefficient expressing the negative strain in the direction of axis no j caused by a positive strain in the direction of axis no i j v j for o and all other stresses equal to zero OY C Yo Tij C Ti a
169. ape does not constitute a part of neither the geometry model nor the FE model The following shapes are available and defined by the DEFINE command Plane Cylinder Cone Sphere Interpolation surface between two unconnected sets of lines curves Shapes are used for the following purposes When defining a surface thereby ensuring that the FE mesh to be created for the surface will be projected onto the shape see command DEFINE SURFACE For the same purpose as above but done after defining a surface see command SET PROJECTION For defining points by intersecting three shapes see command DEFINE POINT name SHAPE INTERSECTION For defining curves by intersecting two shapes see command DEFINE INTERSECTION 2 5 Element Library The element types that may be created by Prefem are presented in table Table 2 2 and illustrated in Figure 2 3 Some of the elements are not available in Sestra SESAM S linear analysis program Such elements are SESAM Prefem Program version 7 1 01 JUN 2003 2 5 for use in SESAM s non linear analysis program Advance Names of such Advance only elements are given in parentheses Table 2 2 Element types of Prefem Element type Short ave aoe Description nodes per Name used in command name node TRUSS TESS Truss 2 3 BEAM 2NODES BEAS Beam 2 6 BEAM 3NODES SECB Curved beam 3 6 AXISYMMETRIC CTAQ Axi symmet
170. arded PARAMETERS trnam IDENT MIRROR pointl point2 ROTATE POINT NAMES ANGLES User given name of the transformation matrix Reset the transformation matrix All previous transformations are discarded Define a mirror transformation about a plane normal to the line between two points and halfway between them Names of points used to define a mirror transformation Define a rotational transformation The rotation is defined by a start point an end point and a centre point as follows Imagine a plane through the three points and an axis perpendicular to this plane and through the centre point The rotation will then be the angle formed in the plane about the axis and from the start to the end point The rotation is defined by an angle about an axis After this command an angle in degrees is given If the entry following the angle is a point name then another point SESAM Program version 7 1 start point end point centre degree line name TRANSLATE DISPLACEMENTS POINT MOVE disx disy disz from point to point SCALE scale x scale y scale z NOTES Prefem 01 JUN 2003 5 91 name is expected the two points defining an axis If a line name is entered then this is taken as the axis Name of start and end points for either of the rotation methods Centre point about which the rotation is performed Rotation angle in degrees Name of a line to be used as an axis Define a translational transformation
171. arious program messages appear in the message window Figure 3 1 illustrates the three Prefem windows on a PC Graphic mode window Print window Message window Figure 3 1 The Prefem windows on PC On Unix there is only a line mode window in addition to the graphic mode window I e the print and mes sage windows are replaced by a line mode window where print requested by the user as well as program messages appear The line mode window is also where line mode input is entered if you do not use the graphical user interface see Section 4 1 4 on this Prefem offers two modes of input and both are available in the graphic mode window Line mode input i e typing commands using the keyboard Graphic mode input i e selecting commands by clicking the left mouse button LMB A sketch of the graphic mode window is shown in Figure 3 2 together with explanations of the six different areas The true appearance of the graphic mode window is shown in Figure 3 6 How to use the areas is explained in more detail in the following You may at this stage decide to go through a brief tutorial Go then to Section 3 2 and use the explanations of the areas of the graphic mode window below for reference SESAM Prefem Program version 7 1 01 JUN 2003 3 3 click left mouse button LMB to select command or action Graphic display area View Present Add display Pan Col Thi Change Rotate Col Mat Check X ax
172. ase GRAVITY GRAVITY GLOBAL FLEXIBLE PART CONTRIBUTION TRANSFORMED trnam 8x gy 2 STIFF END CONTRIBUTION PURPOSE The command defines a constant acceleration field which is used to create an inertia load e g the gravita tional load The three components of the acceleration field are specified the analysis program Sestra will compute the inertia load taking the volume of the elements and the material density into account Point masses will also contribute to the gravity load PARAMETERS GLOBAL TRANSFORMED trnam FLEXIBLE PART CONTRIBUTION STIFF END CONTRIBUTION 8X By BZ The inertia load refers to the model s cartesian coordinate sys tem The inertia load refers to a previously defined transformation of the cartesian coordinate system see the command DEFINE TRANSFORMATION Name of a previously defined transformation This is only relevant for beam elements and involves that if ec centricities offsets are employed the flexible part of the beam rather than the node to node part will contribute to the inertia load For other elements types this entry is neglected The node to node part of beam elements contribute to the iner tia load i e eccentricities if present are neglected when calcu lating the inertia load The three components of the acceleration field The default val ues accepted by hitting carriage return are gx 0 gy 0 gz 9 81
173. ay be performed until the content of the set is as desired The operations are exe cuted consecutively the order of the operations is therefore of consequence When either of the three set operators UNION WITH SUBTRACT BY INTERSECTION WTTH are chosen repetitive selections of geometry elements and nodes may be performed Conclude this sequence by entering END Then a new operator may be chosen and new repetitive selections may be performed Finally the definition or changing of the set is concluded by entering another END rather than one of the set oper ators PARAMETERS name User given name of the set to define maximum 8 characters INTERSECTION WITH All geometry elements and nodes except for those subsequent ly selected will be removed from the set I e the new contents of the set will be the intersection between the current contents of the set and the subsequent selection Prefem 5 82 SUBTRACT BY UNION WITH set name ALL BODIES select bodies ELEMENTS select elements LINES select lines NODES select nodes POINTS select points SPRING DAMPER select spring damp SURFACES select surfaces EXAMPLES SESAM 01 JUN 2003 Program version 7 1 The subsequently selected geometry elements and nodes will be removed from the set The subsequently selected geometry elements and nodes will be added to the set A previously defined set All points all lines all surfaces al
174. ayers Figure 3 56 Layered element for modelling plate and stiffener Layered elements are multilayered shell elements comprised of any number of layers through the shell thickness Each layer is either a plate with isotropic material properties or a stiffener layer A stiffener layer consists of uniformly distributed stiffeners with bar sections The material of the stiffeners is isotropic but the stiffener layer will in effect be an orthotropic layer The layers are not allowed to overlap Overlapping layers will produce correct displacements but incorrect stresses The restriction that layers cannot overlap implies that a plate with an orthogonal set of stiffeners cannot be modelled i e a layered element can only model stiffeners in one direction There are two solutions to this problem Model the stiffeners in one direction the stiffeners with the largest spacing the primary stiffeners by beam elements and include only the secondary stiffeners in the layered element Include both stiffener directions in the layered element by modelling each of them by interwoven non overlapping stiffener segments fingers as shown in Figure 3 57 The segments must have double thickness compared to the true stiffener in order to get proper area Prefem SESAM 3 66 01 JUN 2003 Program version 7 1 wer height The stiffeners in both directions in this case only flatbars have been split into interwoven fingers The thickness of the
175. be a small cut corner See Section 3 4 4 for an explanation of this option See Section 3 4 4 for an explanation of this option See Section 3 4 4 for an explanation of this option See Section 3 4 4 for an explanation of this option See Section 3 4 4 for an explanation of this option See Section 3 4 4 for an explanation of this option See Section 3 4 4 for an explanation of this option See Section 3 4 4 for an explanation of this option See Section 3 4 4 for an explanation of this option See Section 3 4 4 for an explanation of this option See explanation for option RECTANGULAR below This option allows creating a regular rectangular mesh quadri lateral elements for an L shaped surface The mesh of such a surface will otherwise be distorted Note that the number of el Prefem 5 242 surface line number of elements VERSION version number LATEST SESAM 01 JUN 2003 Program version 7 1 ements of opposite lines must be consistent with a regular rec tangular mesh See Figure 5 56 Select a surface A line of the surface Which to select is shown in Figure 5 56 Note that the prompt for this information is misleading Number of elements along a line Which to select is shown in Figure 5 56 Note that the prompt for this information is mis leading Set version of meshing algorithm New versions of Prefem may and may not include updates to new version of the meshing algorithm This option allows us
176. beam cross section Guidance in how to choose a consistent set of units for your analysis is also found here 1 4 Status List There exists for Prefem as for all other SESAM programs a Status List providing additional information This may be Reasons for update new version Prefem SESAM 1 6 01 JUN 2003 Program version 7 1 New features Errors found and corrected Etc Use the program Status for looking up information in the Status List Use the command HELP to start Sta tus SESAM Prefem Program version 7 1 01 JUN 2003 2 1 2 FEATURES OF PREFEM Prefem is a general purpose interactive graphic program for modelling of FE models 2 Modelling Principles The modelling principles of Prefem are based on a dual model concept see Figure 2 1 A geometry model consisting of the entities points lines and curves surfaces and bodies The user defines this model A FE model consisting of elements joined in nodes The program automatically creates this model based on the geometry model and data determining the FE mesh geometry model FE model Figure 2 1 Dual model concept user defines the geometry model program creates the FE model Prefem SESAM 2 2 01 JUN 2003 Program version 7 1 Properties such as material data boundary conditions loads etc are assigned or connected to the geometry and automatically transferred to the FE model This simplifies the input of properties It also allows the user to ch
177. been entered conclude by END NOTES The SET NUMBEROF ELEMENTS and SET MAX ELEMENT LENGTH commands cannot be used for a node line As explained above the node line specifies the position of all boundary nodes including the mid side nodes for higher order elements The effect of this is that the number of elements created along the node line will depend on whether lower or higher order elements are created For example only two 3 node beams will be created for the node line of Figure 5 24 whereas four 2 node beams will be created This is different from what is the case for lines and curves for which the number of elements is given explicitly Also note that if higher order elements are to be created for a node line the number of point nodes on the node line must be an odd number The direction of the node line going from start point to end point has consequence for the local coordinate system of beam elements start point end point name next point Figure 5 24 Node Line SESAM Prefem Program version 7 1 01 JUN 2003 5 71 DEFINE PARAMETER PARAMETER name value PURPOSE The command defines a value that later can be used in place of a real value in certain commands This opens for parametric modelling to some extent The parameter may be used in the commands DEFINE POINT point lt X paral Y para2 Z para3 gt CHANGE POINT point lt X paral DY para2 gt PARAMETERS name User given name of
178. buttons while referring to the descriptions of these in Section 3 1 If you want to perform a static analysis of the model and view the results do as follows Leave Prefem by clicking EXIT Provided that the box Write superelement on exit in the General Mod elling window by which Prefem is started was checked when entering Prefem the Input Interface File see Section 2 13 1 will now be written If this box was not checked then check it enter Prefem once more and exit RunSestra from Manager remember to choose the Multifront equation solver Start Xtract from Manager selecting Default Command input file will present the displacement of result case 1 You may now want to learn more about geometry modelling FE model creation defining and assigning properties as well as defining loads Section 3 3 through Section 3 6 deal with these topics 3 3 Geometry Modelling A model will always have a cartesian coordinate system to which the geometry will refer A geometry model consists of the entities points lines curves surfaces and bodies Geometry is defined by Prefem SESAM 3 16 01 JUN 2003 Program version 7 1 Direct definition of geometrical entities using the command DEFINE Copying previously defined geometry using the command COPY Generation of regular geometry using the command GENERATE Extruding and copying geometry using the command EXTRUDE Cutting command CUT and joining command JOIN
179. cccssssscccsssececessecccessseccsssesessessesesssseeecessssccssssseesssseeessuss 5 249 SIM M OIBHECIUDI RM T 5 250 SEP PRO Des enero eee tert actes rotes iones ose oc estet Udo e ifebr ees Istis 5 251 Uugud DJ OV VIDEREM 5 253 SET PRINT nete eret ete ERG OE UE ct ede e a c Fe ERES 5 254 SET TASK cn cacy ave s I P RR Ma S aaa dea s Ad ade did De ie qut us 5 258 SET TOLERANCE 52 ecco readies escheat vagy pean Onda te e dde a a RR en 5 260 SET WRITE MOBE bye EROS eO ne pb RAE De rpne bur R SS 5 261 WW TRIE sce Pc HO Ww 5 262 ZOOM aps HU EROTIC eo bte isis Pd A DA QUPD NUR NI B RPM A M 5 263 CA PRIMIS BEER ORO SLARSSIPHIRUT RUNE ERO NEST URERN a RT LEAF THU S 5 264 APPENDIX A TUTORIAL EXAMPLES ee eee eee eese seen eese en osten seen sete en sete se sesso seen A 1 ADs Midship Section iie RS DRIED tete e teen t det deeds A 1 A2 Cylindrical Tank with Flat Bottom and Spherical Top sse A 4 APPENDIX B THEORY i csssssesscsssecsdsaspnssoonstoedassueudsoouspedevessoeues ossassoousbecsosdvonasseesssccseseacaver B 1 B1 Formulae for Sectional Parameters sse eee enne tenens B 1 Bj Barsect onguuscde tent er eese ien e stedetente ini qe e ue ruo uda B 3 B1 1 1 Sectional DIMENSIONS inienn kaane Ea enne nnne nnne B 3 B 1 1 2 Sectional Parameters Computed esses eene B 3 IIoc umm B 5 B1 2 1 Sectional Dimensions esssseeseeee ener nnne enne B 5 B 1 2
180. ces then need to be selected Element Display selected elements the elements then need to be selected Mesh Display the FE mesh SESAM Prefem Program version 7 1 01 JUN 2003 3 5 e e Add Mesh Add display of the FE mesh to the currently displayed geometry Add Load Add display of loads to the currently displayed FE mesh Label e e e e e Boundary Toggle switch on and off symbols for boundary conditions Points Toggle name of points Lines Toggle name of lines Surfaces Toggle name of surfaces Geometry Toggle name of all geometry names points lines surfaces and bodies Nodes Toggle node numbers Elements Toggle element numbers Supernod Toggle symbol blue octagon for supernodes Mesh Toggle node and element numbers plus symbol for supernodes All Off Switch off all labels names numbers and symbols Default e Mesh Adj Toggle switch on and off the feature Whenever the number of elements or maxi mum element size is changed for lines do the following Adjust mesh refinement starting with the lines next to the lines for which the discretisation has been changed and propagate outwards until a mesh for the whole model can be made See the SET DEFAULT ADJUST MESH and MESH ADJUST commands Direct access buttons These buttons are accessible at any time Le when you are in the middle of a command by clicking a command or a Shortcut com
181. changed by the CHANGE NODE command the command RE COMPUTE LOADS will re compute the transfer of the loads from geometry to nodes and elements This is required to get a correct display of a load the ADD DISPLAY LOAD command after a change has been made The loads will always be re computed when the Input Interface File is produced When the element mesh is changed it is best to RE COMPUTE load cases with varying loads The PRINT LOAD command tabulates loads selected for load cases load types and geometries The ADD DISPLAY LOAD command displays graphically selected loads on the FE mesh currently dis played SESAM Prefem Program version 7 1 01 JUN 2003 3 55 3 7 Varying Value Input by Functions Surface thickness and loads surface pressure line loads temperature concentrated loads prescribed dis placements and prescribed accelerations can be specified as values varying in space Rather than giving a single numeric value where a value is requested a function describing the load or thickness variation in space may be entered A function is defined based on a set of pre defined basic functions mathematical functions arithmetric operators and constants The various basic and mathematical functions are described in detail in Section 5 3 Introductory explanations are found below The basic functions available are LINEAR 2POINTS VARYING LINEAR 3POINTS VARYING LINEAR RADIUS VARYING CYLINDRICAL ANGLE VARYING CYLINDRICAL
182. cific damping coefficients for the first and second material axes of anisotropy alphal alpha2 Thermal expansion coefficients for the first and second material axes of anisotropy dll d21 d22 The lower triangular general anisotropic elasticity matrix 5 1 d31 d32 d33 NOTES An orthotropic material is defined by taking advantage of the fact that 1t 1s a special case of the anisotropic material To define an orthotropic material in its principal axes the lower triangular part of the general aniso tropic elasticity matrix should have zero values for some of the terms Prefem SESAM 5 178 01 JUN 2003 Program version 7 1 dll d21 d22 5 2 0 0 d33 The elasticity matrix of an orthotropic material expressed in terms of the Young s modulus the shear modu lus and Poisson s ratio is given below The stress strain relationship o D is E vE 0 i 9 7 TT VE E 0 E 5 3 Tiz 0 0 Gill Vi5V3 72 where j 0 and amp are the strain stress and Young s modulus respectively in the direction of axis no i vij is the coefficient expressing the negative strain in the direction of axis no j caused by a positive strain in the direction of axis no i j v j for o o and all other stresses equal to zero Yi2 V21 T12 T21 and G5 G5 are the shear strain shear stress and shear modulus respectively in the plane defined by axes nos 1 and 2 Hence the terms of the elasticity matrix becomes dll E
183. coordinates mode gt Conclude the update coordinates mode update coordinates See explanation under the DEFINE POINT command NOTES If the new position of a point coincides with any other point then the change is not performed The position coincides if the distance is less than the coordinate tolerance given by the SET TOLERANCE COORDI NATE command EXAMPLES The following command changes the coordinates of point P1 to 1 2 3 CHANGE POINT P112 3 The following command adds 4 25 to the Z coordinate of all points starting with AP21 CHANGE POINT AP21 DZ 4 25 Prefem SESAM 5 38 01 JUN 2003 Program version 7 1 CHANGE PROPERTY LOAD load case TO MASS PROPERTY LOAD load case TO MASS load type grav lc select geometry PURPOSE The command converts certain load types to nodal masses These load types are CONCENTRATED i e loads applied to nodes Plus the following load types applied to two node beam elements LINE LOAD PART LINE LOAD BEAM CONCENTRATED LOAD Note Only loads applied to the two node beam element may be converted The conversion of loads to nodal masses is done by computing the consistent nodal forces for the loads in question and then dividing these nodal forces by the acceleration of gravity The acceleration of gravity is taken from a previously defined gravity loadcase The computed masses are added to any previously defined masses for the three tra
184. cted to the accelerations must be given the boundary condition PRESCRIBED ACCEL ERATION using the PROPERTY BOUNDARY command PARAMETERS select geometry GLOBAL TRANSFORMED LOCAL COORDINATE SYSTEM UNTRANSFORMED trnam coord name ax ay az arx ary arz Select geometry See Section 5 1 on how to perform a selection The acceleration components refer to the model s cartesian co ordinate system The acceleration components refer to a previously defined transformation of the cartesian coordinate system see the com mand DEFINE TRANSFORMATION The acceleration components refer to a previously defined cy lindrical or spherical coordinate system see the command DE FINE COORDINATE SYSTEM No additional transformation of the cylindrical or spherical coordinate system is performed Name of a previously defined transformation Name of a previously defined coordinate system Acceleration components Prefem SESAM 5 164 01 JUN 2003 Program version 7 1 iax iay iaz iarx lary iarz Imaginary acceleration components By entering data for these the acceleration field will implicitly become complex Entering END rather than iax iay iarz implies that the acceleration field is real SESAM Program version 7 1 Prefem 01 JUN 2003 5 165 PROPERTY LOAD load case PRESCRIBED DISPLACEMENT PRESCRIBED DISPLACEMENT select geometry GLOBAL TRANS
185. ction line a point on the cian li Plane perpendicular to projection line projection line lt point2 valuez Figure 3 55 Evaluation of LINEAR 2POINTS VARYING point projected onto projection line Prefem SESAM 3 60 01 JUN 2003 Program version 7 1 3 8 Parameters Parameters may be defined and referred to in certain commands This involves defining a parameter by name and giving it a value and thereafter referring to this parameter rather than specifying the value in sub sequent commands This feature opens for some degree of parametric modelling An example is provided below DEFINE PARAMETER PAR1 valuel PAR2 value2 PAR3 value3 DEFINE POINT P1 lt X PAR1 Y PAR2 Z PAR3 gt CHANGE POINT P2 lt X PAR1 DY PAR2 gt Note The command DEFINE POINT P1 PARI is not allowed This because the parameter may only be used in situations where a real value is the only alternative available and not for example END 3 9 Selecting Geometry using Wild Cards and defining Sets The following ways of selecting geometry are explained Graphical selection Line mode command selection e Wild card selection Selection through set 3 9 1 Graphical Selection of Geometry Whenever there is a need for selecting geometry e g when boundary conditions are defined and when loads are defined you may select geometry graphically There are three ways of doing this Clicking the left mouse button LMB Dra
186. cy between one point or rather the node in that point and two other points nodes in those points The linear dependency will be valid for all d o f s of the nodes TWO NODE DEPENDENCY defines linear dependency between one node and two other nodes The difference between this and the previous item is that TWO POINT DEPENDENCY refers to nodes through point names while TWO NODE DEPENDENCY refers to node numbers directly and will be deleted if the mesh is deleted GENERAL NODE DEPENDENCY defines linear dependencies between any d o f of a node and any other d o f s of any other nodes As the command refers to node numbers directly the property will be lost if the mesh is deleted LINE LINE DEPENDENCY defines linear dependencies between all or selected d o f s of nodes on a pair of lines The pair of lines must have exactly the same location overlap This feature is convenient for coupling adjoining surfaces that have overlapping lines rather than sharing common lines Such over lapping lines for adjoining surfaces is in conflict with normal modelling practice but may be used in cer tain situations e g to let the adjoining surfaces have different number of elements in the same position or incompatible element types 4 and 8 node shell elements RIGID BODY DEPENDENCY defines linear dependencies between all or selected d o f s of several nodes and a single node This feature is convenient for making an infinitely stiff coupling bet
187. d by ALL the latter command means read all commands found on the file Alternatively you may specify a command input file when start ing Prefem from Manager The model file MOD is the binary data base containing all model data The file cannot be read by a text editor The print file LIS is an ASCH file which contains tables over data requested for printing by the PRINT command Prefem SESAM 4 6 01 JUN 2003 Program version 7 1 The plot file contains graphic information produced by the PLOT command The file extension will depend on the plot format chosen see the SET PLOT FORMAT command See Section 4 1 6 for advice on using the CGM format to include plots in reports The Input Interface File FEM termed T file for short contains the model to be read by a subse quent hydrodynamic or structural analysis program Prefem has been designed to protect the user against loss of valuable data However accidental loss of data may occur This may be caused by the user by for example inadvertently deleting the model file or it may be due to an inconsistency in the data model Such inconsistency may occur for several reasons The computer goes down The disk is full the disk quota is exhausted or user privileges are inadequate There is an error in the program If Prefem discovers an inconsistency in the data model the program will normally close all files opened and abort th
188. d by the projection onto the element of the global X axis If the global X axis is normal to the element then the local x axis of the element will be parallel with the global Y axis The GLOBAL option ensures that a layered element will have the same local coordinate system as a shell element for which the local coordinate system is calculated by Sestra TRANSFORMED The local x axis of the element is defined by the projection onto the element of the X axis of a transformed coordinate system This transformed coordinate system must previously have been defined by the DEFINE TRANSFORMATION command If the transformed X axis is normal to the element then the local y axis of the element will be parallel with the transformed Y axis Note that this solution to situations where the X axis is normal to the element plane differs from that of the GLOBAL option This means that even when the transformation matrix equals the identity matrix the TRANSFORMED and GLOBAL options will give different results in certain situations This option ensures that neighbouring layered elements in most cases will have smooth transitions in local coordinates even in cases where the normal shell elements will have discontinuity in their local coordinate systems If this behaviour is preferred Prefem 5 174 LOCAL COORDINATE SYSTEM UNTRANSFORMED coord name trnam NOTES SESAM 01 JUN 2003 Program version 7 1 you may use this option with the iden
189. d element mesh for a body must be prismatic i e the discretisation mesh topology of the top and bottom surfaces must be equal so that there is no mesh refinement in the top bottom surface direc tion This is consistent with the requirement to the geometry Sum of elements 2 2 3 4 3 14 is an even number therefore only quadrilaterals Sum of elements 242434444 15 is an odd number therefore a triangle in the corner Figure 2 4 Surfaces with odd and even sum of number of elements 2 2 2 2 HA m Ud 6 4 9 5 Figure 2 5 Surfaces with impossible and possible mesh refinements 2 71 4 Constraints on Element Loading Several types of loads may be defined in Prefem concentrated load line distributed load surface normal pressure etc Not all types of loads can be applied to all types of elements Table 2 3 shows the relevant types of loads for the various types of elements of the Sestra analysis program Refer to the relevant user manual for other analysis programs Some of the types of loads created by Prefem are related to the nodes rather than to the elements These are therefore allowable independently of the type of element used These elements are e Concentrated nodal load including forces and moments Prefem SESAM 2 10 01 JUN 2003 Program version 7 1 Prescribed nodal displacement Prescribed nodal acceleration Rigid body acceleration Rigid body velocity Table2 3 Allowable loads for a Sestra analysis
190. ded Prefem 5 204 SESAM 01 JUN 2003 Program version 7 1 PROPERTY TRANSFORMATION PURPOSE TRANSFORMATION trnam ARBITRARY point point2 angle GUIDING POINT spx spy Spz gpx gpy gpz GLOBAL X ROTATION Y Jangle LOCAL F The command defines a geometrical transformation consisting of pure rotations of the cartesian coordinate system Transformations are used in copying geometric entities for defining boundary conditions and loads in transformed askew coordinate systems and for orientating spring to ground and damper to ground ele ments Alternatively to this command the DEFINE TRANSFORMATION command may be used The user may find that solely using the DEFINE TRANSFORMATION command is best as it is more powerful than the PROPERTY TRANSFORMATION command PARAMETERS trnam ARBITRARY point point2 angle GUIDING POINT SPX Spy spz 8px gpy gpz ROTATION GLOBAL LOCAL User given name of the transformation matrix Define a rotation about an axis defined by two points Two points defining the axis Positive rotation is according to the right hand rule Rotation angle Positive direction is defined by the right hand rule Use guiding points to define a rotation A second point SP and a guiding point GP are defined The x axis of the transformed coordinate system Xr goes from the origin and through point SP Point GP lies in the XT Z4 plane on the po
191. deleted The DEFINE SECTOR CORNER command cuts holes in surfaces as illustrated in Figure 3 22 Alterna tively to deleting the corner as shown in the figure the corner complement the whole surface but the cor ner may be deleted and none of the two surfaces may be deleted The command will after selecting one surface and choosing which surface to delete allow repeating the process for the neighbouring surfaces thereby completing the process of making a round hole Round off a corner by selecting clicking lines on Make hole by giving radius selecting clicking both sides and giving radius then delete corner point selecting surface and delete corner selecting next surface and delete corner etc DEFINE ROUNDED CORNER LI1 LI2 3 5 DEFINE SECTOR CORNER 3 5 P1 CORNER S1 CORNER S2 CORNER etc LI2 A LII VN x Figure 3 22 Rounding off corners and cutting holes SESAM Prefem Program version 7 1 01 JUN 2003 3 27 3 3 7 Generating Geometry See Section 3 3 9 for a brief discussion on the GENERATE command versus the EXTRUDE command The GENERATE command is available for highly efficient generation of regular geometric shapes A regu lar geometry is in a cartesian system a geometry consisting of surfaces all shaped as parallelograms The command is based on first defining a topological I J K space and then by use of vectors mapping this space into a geometrical coordinate system See Figure 3 23 fo
192. e DEFINE SHAPE command NOTES Alternatively to using this command the DEFINE SURFACE command may have defined such projection see this Prefem SESAM 5 258 01 JUN 2003 Program version 7 1 SET TASK FRAME ON ELEMENT TYPE SHELL OFF SOLID ONLY FULL MENUS SHORT MENU MODE TASK LONG MENU MODE GEOMETRY ON PROPERTY OFF MODELLING ae LOAD ONLY MESH PURPOSE This command enables suppressing commands irrelevant for the current task The two filters MODELLING and ELEMENT TYPE can be applied at the same time These filters switches on and off commands related to various modelling features The SHORT MENU MODE and LONG MENU MODE are qualifiers that can be selected in addition to the filtering PARAMETERS ELEMENT TY PE FRAME SHELL SOLID ON OFF ONLY FULL MENUS SHORT MENU MODE Filter for element types Switch for frame type elements 1 D elements Switch for shell type elements 2 D elements This switch also encompasses 1 D elements Switch for solid type elements 3 D elements This switch also encompasses 1 D elements Switch on the selected modelling feature Switch off the selected modelling feature Switch on the selected modelling feature and switch the other features off Suppress no commands at all As if LONG MENU MODE is selected and all switches under the filters are switched on Suppress less used commands SESAM Prefem Pr
193. e defined prior to requesting the automatically calculated eccentricity The eccentricity is constant along each line unless the plate shell thickness varies and automatic calculation of eccentricity is requested SESAM Prefem Program version 7 1 01 JUN 2003 3 49 section through shell and beams section through shell and beams with no eccentricities after CALCULA TED NEGATIVE Z OFFSET Figure 3 49 Automatically calculated eccentricity for L and I sections 3 5 4 Thickness All surfaces for which 2 D elements membrane plate and shell elements are created must be assigned a thickness Surfaces with axi symmetric elements however need no thickness The PROPERTY THICK NESS command is used for this purpose Observe that rather than giving a single value for the thickness i e a constant value over the surface a varying thickness can be defined by varying value input see Section 3 7 3 5 5 Local Coordinate System for Surface Elements For most 2 D elements membrane plate and shell elements the local coordinate system is not defined within Prefem The local z axis surface normal is implicitly defined by the way the surface was defined the right hand rule combined with the sequence in which the lines where referred to when defining the sur face determines the general direction of the local z axis The exact direction of the local z axis and also the orientation of the local x axis and y axis are determined by the analysis progra
194. e execution Prefem may then be restarted using the model file In some cases however it will not be possible to resume normal execution due to an irrecoverable inconsistency If the model file is lost it can be reconstructed by re executing the program and reading input from the command log file i e using it as a command input file Note The model file will normally not be compatible between different versions of Prefem The command log file may however be used as input to a new version 4 1 6 Creating Plots for Reports The CGM plot format see the SET PLOT FORMAT command is well suited for importing SESAM plots into reports produced by MS Word and other word processors You may also transfer CGM files from one operating system to another just make sure to use the binary option when transferring the file with FTP or another protocol Depending on the capabilities of your word processor the PostScript plot format may also be used for the purpose of importing SESAM plots into reports Contrary to CGM PostScript is an ASCII formatted file and is therefore more easily transferred from one computer make to another Note that a word processor will normally recognise only one picture display on each file You should therefore specify a new file name for each plot command using the SET PLOT FILE command 4 1 7 Background Execution On Unix the user may find it convenient to execute Prefem as
195. e line start point Name of the point defining the start point of the line end point Name of the point defining the end point of the line nelm Number of elements to be created along the line See also the commands SET NUMBEROF ELEMENTS and SET MAX ELEMENT LENGTH NOTES The direction of the line going from start point to end point has consequence for the local coordinate system of beam elements tart point name nd point Figure 5 23 Line SESAM Prefem Program version 7 1 01 JUN 2003 5 69 DEFINE MASS ELEMENT MASS ELEMENT ONE NODED mass element name select points material name GLOBAL AT POINT TRANSFORMED trnam ECCENTRIC x y z PURPOSE The command defines general one node mass elements Mass elements are connected to points The mass elements are given names and their material data masses must previously have been defined by the PROPERTY MATERIAL command Mass elements are automatically connected to the nodes created at the points and given element numbers The mass elements are created by the MESH command The DELETE MESH command deletes the mass elements but not their definitions meaning that when the mesh is re created e g by MESH ALL the mass elements will be re created The DELETE MASS ELE MENT command however deletes the definition of mass elements A mass element may have from one and up to six degrees of freedom this is specified in t
196. e mesh cor rect the geometry and re create the mesh Clustered nodes may also be caused by a defect in the mesh In such case the commands DELETE MESH ALL and MESH ALL may resolve the matter PARAMETERS select geometry Select geometry See Section 5 1 on how to perform a selection tolerance The cluster tolerance i e a pair of nodes closer than this dis tance is listed Prefem SESAM 5 42 01 JUN 2003 Program version 7 1 CHECK CLUSTERED POINTS CLUSTERED POINTS select points set of clustered points tolerance PURPOSE The command picks out geometry points positioned closely together and stores these in a named set The set of clustered points may then be printed or displayed PARAMETERS select points Select points See Section 5 1 on how to perform a selection set of clustered points Name of a new set to be created by this command tolerance The cluster tolerance i e if points are more closely positioned than this distance then they are put into the set SESAM Program version 7 1 Prefem 01 JUN 2003 5 43 CHECK ELEMENT SHAPE ELEMENT SHAPE select elements set of failed elements MINIMUM min ANGLE MAXIMUM max BOTH MINIMUM AND MAXIMUM min max ASPECT RATIO _ ratio REPORT FAILING ELEMENTS TWIST twist angle END PURPOSE The command picks out elements failing specified criteria and stores them in the named
197. e of elements corners Aspect ratio of the elements i e largest distance between two corner nodes divided by shortest Twist of elements In addition to specifying the type of check to perform and limiting values the CHECK ELEMENT SHAPE command will request the name of a set see Section 3 9 4 into which the elements failing the test will be put This set containing bad elements may then be displayed The command sequence will typically be CHECK ELEMENT SHAPE geometry set namel ANGLE MAXIMUM MINIMUM value set name2 ASPECT RATIO value set name3 TWIST value DISPLAY geometry ADD DISPLAY ELEMENT set namel set name2 set name3 An alternative way of displaying the bad elements is DISPLAY ELEMENT set namel set name2 set name3 LOCATE Figure 3 66 illustrates the use of the CHECK ELEMENT SHAPE command Prefem SESAM 3 74 01 JUN 2003 Program version 7 1 The mesh for a twisted surface The surface with Check for angles less than 60 dimensions 8 by 10 has its fourth corner out of plane by a distance of 2 The 4 node elements will SET1 ANGLE MINIMUM 60 then be somewhat twisted CHECK ELEMENT SHAPE ALL SURF INCL Check for aspect ratio greater than 2 Check for twist greater than 4 CHECK ELEMENT SHAPE ALL SURF INCL CHECK ELEMENT SHAPE ALL SURF INCL SET2 ASPECT RATIO 2 SET3 TWIST 4 Figure 3 66 Checking FE mesh for angles aspect ratios and twist 3 12 3 Modelling Co
198. e of the point to which end 1 of the axial spring is to be connected Name of the point to which end 2 of the axial spring is to be connected Name of a previously defined material of type spring AXIAL or TO GROUND whichever is relevant Use the cartesian coordinate system of the model The spring stiffness matrix refers to a transformed coordinate system Name of the transformation used SESAM Prefem Program version 7 1 01 JUN 2003 5 87 DEFINE SURFACE first line name opposite line name MESH CORNERS or line name j NOT MESH CORNERS MESH CORNERS or oin name NOT MESH CORNERS END m SURFACE name shape PURPOSE The command defines the geometric entity surface A surface can have any number of borderlines curves Surfaces can be defined as follows see Figure 5 33 a By giving the name of a line curve and another line curve not connected to the first one A quadrilateral surface is formed in between these two opposite lines curves Unless they already exist two straight lines connecting the two selected lines curves will be created The lines created are given default names By giving the names of all lines curves enclosing the surface By giving the names of the points surrounding the surface Unless they already exist straight lines be tween these points will be created The lines created are given default names The list of points is conclud
199. e to a single choice In the example below command A is followed by either of the commands B and C Thereafter command D is given Legal alternatives are therefore A B D and A C D B A D C In the example below command A is followed by three selections of either of commands B and C as indi cated by 3 For example A B B B or ABB C or A C BC etc B A 3 C In the example below the three dots in the left most column indicate that the command sequence is a contin uation of a preceding command sequence The single asterisk indicate that B and C may be given any number of times Conclude this sequence by the command END The three dots in the right most column indicate that the command sequence is to be continued by another command sequence B A C END In the example below command A is followed by any number of repetitions of either of the sequences B D and C D Note that a pair of braces is used here merely to define a sequence that may be repeated The braces are not commands themselves B A D i tk jj The characters A B C and D in the examples above represent parameters being COMMANDS written in upper case and numbers written in lower case All numbers may be entered as real or integer values Brackets are used to enclose optional parameters Prefem SESAM 5 2 01 JUN 2003 Program version 7 1 Note The
200. e use Prefem can be run in batch mode as explained in Chapter 4 For comprehen sive modelling work you may find that editing an input file which initially may have been a log file is an efficient and complementary way of working to running Prefem in interactive mode Prefem either creates a complete FE model or a first level superelement constituting a part of the complete model The difference between the two as seen from Prefem is that there are some supernodes or Figure 1 1 shows an example of a FE model that can be modelled by Prefem super degrees of freedom defined for the latter The term superelement Figure 1 1 FE model with plate elements plus beam elements for stiffeners SESAM Prefem Program version 7 1 01 JUN 2003 1 3 1 2 Prefem in the SESAM System Additionally to Prefem SESAM comprises a set of preprocessors that are dedicated to various modelling purposes SESAM s preprocessors are Preframe Modelling superelements consisting of beam truss and cable elements Patran Pre Modelling superelements of arbitrary shape and complexity consisting of beam membrane shell and solid elements Prefem Modelling superelements consisting of beam membrane shell and solid elements Presel Assembling superelements to form the complete model In addition to these preprocessors SESAM is comprised of a set of hydrodynamic analysis programs a set of structural analysis programs and a set of postprocessors The SESAM syste
201. eady considered to be a line in the cylindrical spherical coordi nate system This implies that using the CHANGE LINE command for such a curve will change it into another line in the cylindrical spherical coordinate system i e a curve A curve may however be changed to an arc or a spline and this arc or spline may in turn be changed into a straight line Figure 5 15 exemplifies this CHANGE ARC CHANGE LINE Adil API APIS PO 4 JU sei AP12IL 4 PO PO x X GENERATE SURFACE A Pl Pl CYLINDRICAL API11 C API11I xX Xx me Appi PX NBI Pl Dad APII1 X This is an arc m 7 AIL AP121 CHANGE Liwa These changes may be done Curve resulting from wA RE APIIL PI even when the line curve is a GENERATE is a line in oe borderline of a surface the cylindrical spherical Pl coordinate system APIII s P B This change may not be done AP121 i i x when the line curve is a borderline of a surface this This is a curve or line in because the start end points cylindrical spherical system do not remain the same Figure 5 15 Changing a curve resulting from GENERATE in cylindrical spherical systems Prefem SESAM 5 28 01 JUN 2003 Program version 7 1 Note Lines curves will also change by changing the coordinates of the points defining the lines curves i e using the CHANGE POINT command Note A curve resulting from using the GENERATE command in a cylindr
202. eak character to either ASCII charac ter 12 format ASCII or to the FORTRAN standard of 1 in the first column format FORTRAN ASCII format is default and will give proper page breaks when printing on laser printers and when importing into word processors Set the size of the graphical user interface window or graphic display window This is available on Unix only The value to give is percentage of screen height By default size 90 Note the following about how to enter command line arguments Command line arguments and values can be abbreviated Each argument name must begin with a slash and each argument value must be preceded by an equal sign Spaces can freely be distributed around the equal sign and before each slash Texts with blank spaces and special characters e g file names must be enclosed in quotes Note that some operating systems change the case of the input text if it is not enclosed in quotes Slanted arguments or values indicate that these are defaults fat least one of the arguments PREFIX NAME and STATUS is specified then the prompt for data base and journal file name is skipped and defaults are used for any unspecified values The values given to the EYEDIR are real values The default is the Prefem default values If one of the three are given the other two are set to 0 0 unless specified n some cases a virtual screen larger than the real screen is used e g when a PC through an
203. eas este dak dis e be dead tee e ORE ant ag Ce DARREN eed 3 25 3 3 9 Jommg Geometry c etr ei tbe le aite dri ete ties re dates 3 26 3 3 6 Rounding off Corners and Cutting Holes sese 3 26 3 97 Generating Geometry see eere A e REUTERS DAR EUR 3 27 3 3 8 Extr ding Geometry tec erede ETE re e oet a in ep Cede er regie eed 3 33 3 3 5 The GENERATE Command versus the EXTRUDE Command s sesessss 3 34 3 3 10 Importing DXF File ttp cnr e ta i eee e RR nte eas 3 34 3 34 Geometry Names ond eere QT E UE EUR Nee whe AR 3 34 Creating the FE Model vic ru etate re T e ed E etudes 3 35 3 4 1 Controlling the Mesh Creation sssssesseesee eene eren 3 36 3 4 2 Elements for Ports e ect e ee d te ete UTC Gee 3 38 3 4 3 1 D Elements for Lines Curves rissies i eren nennen eren nennen nenne 3 38 344 2 D Blements for Surf cesz o occi e I Ce nie E dation EGERIT URS EE gp 3 39 3 4 5 2 D Elements for Curved Surfaces eren enne nnns 3 44 3 4 6 3 3 D Elements for Bodies sse enne enne nnns 3 46 ZAT Changing the Mesh Created eet eei iren Ideen ET ee a ran snes ee nen 3 46 Defining and Assigning Connecting Properties ccccccecscceseceseeseceseceseeseeceseecseececseeeneeeneeses 3 46 3 54 Beam Cross Section oe he P RET PRO S ee HERE RH e 3 47 3 5 2 Local Coordinate System for Beam sssssssssseseseeeeeen eene 3 47 35 3 Eccentricity for Beam oae ect
204. eating plots for reports Alternative execution modes Program requirements Program limitations 4 1 Program Environment Prefem is available in the following hardware environments Unix computers of various vendors Windows 98 NT 2000 and XP often referred to as PC 4 1 4 Starting Prefem from Manager Prefem 1s started from Manager by clicking Model General Prefem see Figure 3 3 The graphical user interface of Prefem is explained in Section 3 1 Prefem SESAM 4 2 01 JUN 2003 Program version 7 1 On Unix the graphical user interface is based on OSF Motif X Window System 4 1 2 Reading a Command Input File into Prefem In the General Modelling window opening up when giving Model General Prefem in Manager there is a box for specifying a Command input file see Figure 4 1 By default this is set to None Changing this to File name a new box appears in which you may specify a Command input file that will be automatically read into Prefem once the program is started by clicking OK If the box Run interactively after command input file processing is checked Prefem will display the geometry model created by the input file and await inter active user input You may then continue modelling or only verify the current model and leave Prefem by the EXIT command Note If your Command input file constitutes the complete input then make sure the Database status is set to New You need to change Old to New if you previously have run
205. ected the following selection will comprise all lines except lines L1 and L2 the parentheses are required or else the selection is complete after ALL LINES INCLUDED ALL LINES INCLUDED EXCLUDE L1 L2 Note that only bodies may be excluded from a selection comprised of bodies only surfaces may be ex cluded from a selection comprised of surfaces etc The following exclusion will consequently not work P1 is a point ALL LINES INCLUDED EXCLUDE P1 Prefem SESAM 3 62 01 JUN 2003 Program version 7 1 Including geometry names this is relevant after an EXCLUDE command in order to counteract the exclusion The following selection will comprise all lines except those beginning with L see Section 3 9 3 but still including L1 ALL LINES INCLUDED EXCLUDE L INCLUDE L1 EXCLUDE and INCLUDE may alternate as many times as required Note that only the relevant alternatives for selections will be available E g when defining a line load the alternatives ALL POINTS INCLUDED ALL SURFACES INCLUDED etc will not be available The lines surrounding a surface can be selected by giving the name of the surface lines surrounding a body can be selected by giving the name of the body etc Also see Section 5 1 3 9 3 Using Wild Cards for Selecting Geometry Wild card selection and wild card naming combined with a consistent system for naming geometry e g names as produced by the GENERATE command provides for a powerful way of referrin
206. ections to beams and layered element data to surfaces COPY copies geometry thereby defining more geometry Prefem 2 14 CREATE CUT DEFINE DISPLAY EXTRUDE GENERATE HELP JOIN LABEL LOCATE MESH PLOT PRINT PROPERTY RE COMPUTE RE DISPLAY READ ROTATE SET WRITE ZOOM SESAM 01 JUN 2003 Program version 7 1 creates mesh a command equivalent to MESH cuts lines and surfaces thereby defining new geometry defines geometry shapes one node elements layered element data transforma tions coordinate systems parameters displays geometry and FE mesh extrudes and copies geometry generates geometry and efficient way of defining regular geometry provides help on how to get support status of Prefem the Status List and com mands joins two bodies into one labels tags information on display geometry names symbols for nodes and boundary conditions node and element numbers symbols for mesh corners and el ement normals section and material names etc adds dotted lines indicating location of geometry in relation to the displayed mesh creates mesh for the whole geometry or for a selected part of the geometry creates a plot file of the screen display alternatively the geometry or FE mesh iden tified prints data geometry FE mesh loads material data etc defines properties re computes loads In certain situations e g when loads previously defined are be ing chan
207. ed either by entering END or by closing the surface by giving the first point once more opposite line name Sinema line name point name 1 4 dashed lines don t exist i 1 i 1 I U surface definition a 1 1 at l point name 1 Hi 1 V 1 l 1 1 I i prior to surface definition 1 point name surface definition b surface definition c Figure 5 33 Defining surfaces Note Defining a surface by referring to points can only be done when all enclosing lines curves are straight lines A curve e g an arc will not be recognised by the surface definition and a straight line will be created See Figure 5 34 Prefem SESAM 5 88 01 JUN 2003 Program version 7 1 This straight line will be created if the surface is defined by referring to points Figure 5 34 Defining a surface using lines or points The commands MESH CORNERS and NOT MESH CORNERS are optional and work as follows If lines are used to define the surface then the point in between the last given line and the next one shall be a mesh corner If points are used to define the surface then the last given point shall be a mesh corner All subsequent points will be mesh corners until the command NOT MESH CORNERS is given Mesh corner is the default choice This implies that the first relevant option is NOT MESH CORNERS to counteract the default Therefore completely omitting the MESH CORNERS and NOT MESH
208. ed to check it Section 2 13 1 explains the Optimise superelement box In this case let it be unchecked Prefem SESAM 3 8 01 JUN 2003 Program version 7 1 RE 7 Els EBE e REE Figure 3 3 Manager and the General Modelling Prefem start up window Click OK in the General Modelling window and Prefem will start and the graphic mode window will appear see Figure 3 2 and Figure 3 6 In this tutorial we will create a model of a midship section with geometry dimensions and boundary condi tions as shown in Figure 3 4 The desired FE mesh plate thicknesses and loads are as shown in Figure 3 5 Units are metre Newton and kilogram Refer to Appendix A 1 for the full line mode input SESAM Program version 7 1 01 JUN 2003 50 Girders in these positions n 0 04 2 Units metre Newton kilogram Material Steel Young s Modulus 2 1x10 5 1004 Poisson s Ratio 0 3 0 02 Density 7850 Girder cross section Prefem 3 9 A Boundary condition along these lines FIX FREE FREE FREE FIX FIX FREE FIX FREE FIX FREE FIX B Boundary condition along this line C Boundary condition in these points FIX FIX FREE FIX FIX FIX D Boundary condition in these points FIX FIX FIX FIX FIX FIX Figure 3 4 Tutorial geometry with dimensions and boundary conditions the FE mesh showing load 1 vertical component thicknesses and girders Thickness 2 0E 02 3 0E 02 load 2 hydrostatic
209. eeeeeaaes 3 63 3 10 1 Spring Damper and Mass Elements sssssssesseeeee eene nennen 3 64 3 10 2 Sandwich Elements and Layered Elements sese 3 64 3 10 3 Axi symmetric Elements iieri etre eret trente ede det ette Hi deett 3 66 Transformations and Coordinate Systems essere enne 3 67 3 THAT Transformations eter ei A E e GI E ORAE E root SA Te ERES 3 67 3 11 2 Coordinate Systems onii inin eere eene nennen innen nennen nnn nnns 3 68 Verifying and Checking the Model sssssssseseeeseeere enne ener inneren 3 69 3 12 1 Display and Plot Features enne eene nennen entr enne 3 69 3 12 2 Checking the FE Mesh ite eet eer Rite eee eee eed reet 3 73 3 12 3 Modelling Considerations essere etre nre 3 74 EXECUTION OF PRENFEM cic cicscccssonssces es cette oeto nee eo o Une ae eo ooee de ora Ure Heg e aep ea oues e evo sa epa d euh 4 1 Program Environment re erc ps c dees eo ei eee ette i eg debe 4 1 4 1 1 Starting Prefem from Manager ccccccccsccescssssessecsseceseseeceeeeceseeeseeeseceaeceeeeseeeseeaeenseeeaeens 4 1 4 1 2 Reading a Command Input File into Prefem sess 4 2 4 1 3 Starting Prefem as an Individual Program on Unix eese 4 3 4 1 4 Line Mode Input of Commands and Arguments essere 4 3 4 1 5 Piles used by Prefem eee ese ER RSEN TERRIER Ue Ore 4 4 4 1 6 Creating Plots for Reports eere eet ehe tee nia des n
210. een used LINE ELEMENT MATERIAL BOUND TRANSF CROSS ECCEN NAME TYPE NAME COND NAME SECTION LOAD TRICITY L1 STEEL FFF F L2 BEAM 2 STEEL BOX x LOCAL X 0 400 Z 1 000 L3 STEEL L4 BEAM 2 STEEL LSECT CALC L5 BEAM 2 STEEL LSECT CALC ARC1 BEAM 2 STEEL LSECT CALC Print of geometry information for surfaces The table tells by which lines arcs and curves the surfaces have been defined A plus sign preceding a line name informs that there is a so called not mesh corner between that line and the preceding line in the list SURFACE NAME SHAPE NAME LINES Print of property information for surfaces The table contains property information for surfaces type of element material boundary condition code see Print of point properties above existence of load an x in column LOAD informs that a load has been defined for the line and thickness SURFACE ELEMENT MATERIAL BOUND TRANSF NAME TYPE NAME COND NAME LOAD THICKNESS S1 SHELL 4 STEEL x 5 00000E 02 Print of material data All material types are printed MATERIAL NAME STEEL MATERIAL NUMBER MATERIAL TYPE 1 Linear isotropic elastic structural analysis Young s modulus 2 1000E 11 Poisson s ratio 3 0000E 01 Density 7 8500E 03 Thermal expansion coefficient 1 2000E 05 Prefem SESAM 5 122 01 JUN 2003 Program version 7 1 Print of cross sectional data All cross section types are printed In addition to the given data cros
211. ement name Elements are not deleted only the selected damper element name which has been defined by the DEFINE DAMPER command Delete an axial damper Delete a damper to ground Name of the damper Delete geometric entities See the note below Geometry to delete See Section 5 1 on how to perform a selec tion SESAM Program version 7 1 LAYERED layered name MASS ELEMENT ONE NODED mass element name MESH PROPERTY SET set name SHAPE shape name SPRING AXIAL TO GROUND spring name TRANSFORMATION trnam NOTES Prefem 01 JUN 2003 5 93 Delete a layered element name Finite elements are not deleted only the selected layered element name which has been defined by the DEFINE LAYERED command See the note below Name of the layered element Delete a mass element name Elements are not deleted only the selected mass element name which has been defined by the DE FINE MASS ELEMENT command Delete a one node mass Name of the mass Delete a FE mesh created See a separate description Delete properties See a separate description Delete a set Name of set Delete a shape defined by the DEFINE SHAPE command Name of shape Delete a spring element name Elements are not deleted only the selected spring element name which has been defined by the DEFINE SPRING command Delete an axial spring Delete a spring to ground Name of the spring Delete a transformation defined by either the DEFI
212. ements next point Figure 5 32 Spline SESAM Program version 7 1 Prefem 5 86 01 JUN 2003 DEFINE SPRING AXIAL name point point2 material name GLOBAL TRANSFORMED trnam SPRING TO GROUND name select points material name PURPOSE The command defines a single axial spring element between two points or several spring to ground ele ments connected to points The spring elements are given names and their material data spring stiffness must previously have been defined by the PROPERTY MATERIAL command Spring elements are automatically connected to the nodes created at the points and given element numbers The spring elements are created by the MESH com mand The DELETE MESH command deletes the spring elements but not their definitions meaning that when the mesh is re created e g by MESH ALL the spring elements will be re created The DELETE SPRING command however deletes the definition of spring elements A spring to ground may have from one and up to six degrees of freedom this is specified in the PROP ERTY MATERIAL command PARAMETERS TO GROUND Define a spring to ground element AXIAL Define an axial spring element name User given name of the spring select points point point2 material name GLOBAL TRANSFORMED trnam Select points where spring to ground elements are to be connected See Section 5 1 on how to perform a selection Nam
213. ence Note A T section may be created based on an I section as explained in Figure 3 48 3 5 2 Local Coordinate System for Beam Local coordinate systems must be defined for beam elements in order to orientate their cross sections The PROPERTY LOCAL COORDINATE BEAM command is used to assign a definition to the appropriate lines for which beam elements are created The local x axis will always follow the neutral axis of the beam element and pointing in the direction from the first to the second or next geometry point used in the definition of the line curve Orientating the local coordinate system therefore reduces to orientating either the local y or z axis which again is a matter of ori Prefem SESAM 3 48 01 JUN 2003 Program version 7 1 entating the local y x plane or z x plane respectively As both planes go through the neutral axis the local x axis of the beam element a single point not positioned on the neutral axis will determine the complete local coordinate system This single point or guiding point may be defined in various ways as explained for the command in Chapter 5 Figure 3 48 shows an example of how the PROPERTY LOCAL COORDINATE BEAM is used in combi nation with the PROPERTY ECCENTRICITY command see Section 3 5 3 to make the internal stiffeners of a cylindrical tank point towards the centre of the cylinder and be connected with eccentricities to the nodes the stiffeners are welded onto the inner tank wall The o
214. ent between two mesh corners in which case five mesh corners are allowed see Fig ure 3 39 The number of mesh corners is set by the SET MESH CORNER TYPE command mesh corner no internal mesh line connected to point or only one element adjoining point sum of number of elements for borderlines curves 34 44 34 2 2 14 not mesh corner an even number an internal mesh line connected to point or two elements adjoining point Figure 3 31 Requirements for creating a surface mesh of quadrilateral elements When creating a surface mesh of quadrilateral elements Prefem will attempt to minimise the number of ele ments for each surface and at the same time seek to make the quadrilateral elements as square as possible If you want to avoid the inferior triangular element then make sure the sum of the number of elements for the lines curves surrounding the surface is an even number If the sum is odd then a triangular element will SESAM Prefem Program version 7 1 01 JUN 2003 3 37 be inserted in the sharpest corner or you may manually set in which corner there should be a triangular ele ment For an illustration of this see Figure 2 4 Adjoining surfaces are defined by common lines curves and adjoining bodies are defined by common sur faces As the meshing discretisation sequence is first lines curves then surfaces and at last bodies it fol lows that only one set of nodes is created for the common lines curves for surfaces and c
215. ent thick ness shown and for eccentricity of beam elements It is thus possible to distinguish between line loads on shell elements and line loads on beam elements even when they are applied in the same position load case Load case to add If a load case contains several load types line load normal pres sure etc then only one of the load types may be added at a time You may add more load types and even more load cases to the same display on the screen but once you use RE DISPLAY or make a plot only the last load case and type will ap pear load type Type of load to add See the PROPERTY LOAD command for the different types of loads In addition to specifying a specific type of load the option ALL LOAD TYPES may be given to display all types of loads at once Plotting of ALL LOAD TYPES is however not possible See under NOTES below NOTES If you change the viewing position e g by SET GRAPHICS EYE DIRECTION or ROTATE you should do a RE DISPLAY before you use the ADD DISPLAY command If you use the ALL LOAD TYPES option to display loads then the displayed loads will disappear once you rotate or zoom the model Furthermore a plot will not include the displayed loads SESAM Prefem Program version 7 1 01 JUN 2003 5 25 CHANGE ARC BODY CRACK DAMPER ELEMENT ATTRIBUTE INTERSECTION LINE MASS ELEMENT MESH NAME NODE NODE LINE NORMAL OF SURFACE POINT PRISM PROPERTY ROTATION OF SURFACE SE
216. entric ities into account The display of eccentricities is enlarged by the SET GRAPHICS SIZE SYMBOLS SECTION FACTOR command Beam elements are by default drawn with a line three times thicker than other lines line width scaling 3 With this op tion you may set the line thickness of beam elements equal to standard line width scaling 1 and increase it up to 25 times the standard thickness Draw the beam elements with their sections fully drawn and taking their eccentricities into account The display of eccen tricities is enlarged by the SET GRAPHICS SIZE SYMBOLS SECTION FACTOR command The general section for which only area and sectional proper ties are given 1 e no dimensions is drawn as a bar with height equal to 2 Iy Wymin and width equal to 2 I Wymin Draw the beam elements as solid objects i e with their sections fully drawn and extruded along the beam element length Ec centricities are taken into account The display of eccentricities is enlarged by the SET GRAPHICS SIZE SYMBOLS SEC TION FACTOR command For general section see the explanation for option OUTLINE SECTION This option switches ON and OFF graphic visualisation of ec centricities The visualisation is in the form of narrow triangles rods between the nodes and the beam ends This visualisation may be used independently of the other BEAM ELEMENT settings The display of eccentricities is enlarged by the SET GRAPHICS SIZE SYMBOLS SECTIO
217. eometry name is limited to eight characters the prefix should therefore be limited to a few characters say four in order to avoid any problems for geometry names with high numbers Exiting and re entering the program will not affect the prefix setting Prefem SESAM 5 254 01 JUN 2003 Program version 7 1 SET PRINT ON ALPHABETIC OFF CARTESIAN X AXIS COORDINATE SYSTEM CYLINDRICAL Y AXIS Z AXIS FILE DESTINATION SCREEN FILE file prefix file name PRINT ON ACCUMULATION OFF ALL EXTENT GEOMETRY MESH LOAD 4 DIGITS NODE NUMBER 5 DIGITS DIFFERENCE CHECK ON TEMPERATURE MIDSIDE NODE FF NODAL FROM SOLID PURPOSE The command sets parameters for print PARAMETERS ALPHABETIC COORDINATE SYSTEM CARTESIAN CYLINDRICAL Switch alphabetic sorting in tables over geometry ON and OFF Set coordinate system for output of nodal coordinates Use the cartesian coordinate system of the model This is the default choice Use a cylindrical coordinate system with either of the cartesian axes used as the cylinder axis I e all nodal coordinates are for the purpose of printed output only transformed from the car SESAM Program version 7 1 X AXIS Y AXIS Z AXIS DESTINATION FILE LOAD ACCUMULATION EXTENT NODE NUMBER TEMPERATURE NODAL FROM SOLID MIDSIDE NODE Prefem 01 JUN 2003 5 255 tesian coordinate system of the
218. er segment Spline B spline curve defined by an arbitrary number of points SESAM Prefem Program version 7 1 01 JUN 2003 3 19 Table 3 1 Lines curves and their definitions Type Definition Node line Broken straight lines between an arbitrary number of points and with nodes in the points Curve Curve generated by GENERATE command in cylindrical or spherical coordi nate system The command below defines the straight line L1 between points P1 and P2 It will be discretisised into 4 elements or element edges during meshing DEFINE LINE L1 P1 P2 4 The command below defines the circular arc A1 between P1 and P2 and with PO as centre point A1 will be discretisised into 5 elements DEFINE ARC Al P1 P2 PO 5 The command below defines the intersection curve C1 between the two shapes SH1 and SH2 The end points of the curve are PA and PB PX is a point in the vicinity of the desired one of possibly more intersec tion segments C1 will be discretisised into 3 elements DEFINE INTERSECTION C1 PA PB PX SH1 SH2 3 LI 4 Al 5 Figure 3 13 Defining line arc and intersection The command below defines the B spline curve C2 going through the points P1 through P4 Note that a B spline curve is often best defined if its ends are determined by two closely located points P1 P1X and P4 P4X C2 will be discretisised into 8 elements DEFINE SPLINE C2 P1 P1X P2 P3 PAX P4 8 The command below defines the node line
219. eren e a be n Men 5 47 COPY iiie ed edi P eo e GIG e RUE ER 5 48 iU di 5 51 CREATE DESCRIPTION tacite iode tuii ei b ER E REM RRRERE GENE IRURE 5 52 CREATEMESH einer Eel deret e o d Eire E edere e Pet e LPS ia 5 53 gu EE 5 54 DEPINE seemed a a a a Me ir NE AA NU GEM 5 56 DEFINE ARG 2 iter treten pete tte eite ete cape ai eam vea dte ded ee ees 5 58 DEFINE BODY varerum ete ite da cese diee D Re Ente tee etd eA dr Chav Does dee tre ite dur tad 5 59 DEFINE COORDINATE SYSTEM eee nnen trennen Taa aaa saTanah 5 60 DEFINE DAMPERS icc tette treturteeta tumet ameet iiie iere 5 62 DEPINEINTERSECTION 5 rtr tree teet ar re ae see e eter e RE EIS 5 63 DEFINE LAY ERED 5 3 2 m he Od ai teet ere a ge RR E a FEAR bere RUE 5 64 DEFINE LINE 5 etre tete t t tr ele PUR AR MS ERR R XE ek ren Ive dn aee Ie need 5 68 DEBINEMASS ELEEMENT i eseeett e eene t eR a SARI Eo se Ro T EA Hee ERE ge egent 5 69 DEFINE NODE LINE 45 3 rite ee Re RE OR FERE eas ant ee E re TE 5 70 DERINE PARAMETER 5 ipee rta Lure ee eee e EE E FU Fey Re eye EHE Ud ele 5 71 DEFINE POINT 2i nett bete P eee tr e o P T e te RISE ER ER EIER ERE eY Te Mel 5 72 DEFINE POINT name lt update coordinates gt esses ener 5 73 DEFINE PRISM iter PARERE UE UC RINT oa Sia 5 76 DEFINE ROUNDED CORNER aaae aE E a ns etant Aaa aA TE E ene 5 78 DEFINE SECTOR CORNER eonen c aee eese qe eee epe t eee re e YER de E ee ek e exe TA 5 79 DEFINE SET 5
220. ers are distributed in an infinite plate as opposed to specifically positioned within a finite plate The distance between the stiffeners Whether the plate stiffener layer is eccentric or not is to be specified The plate stiffener layer is eccentric The eccentricity of the plate stiffener layer is calculated by the program so that the layer is moved in negative local z direction of the surface in order not to overlap with the previous layer The eccentricity is to be given by the user The eccentricity given as a vector from the node to the layer The dx and dy components are irrelevant and should be given as 0 0 The plate stiffener layer is not eccentric Prefem SESAM 5 66 01 JUN 2003 Program version 7 1 NOTES A stiffened plate has different area in a section normal to the direction of the stiffeners assuming all stiff ener layers are parallel compared with a section parallel with the stiffeners A section parallel with the stiff eners have the bending stiffness of the plate alone whereas a section normal to the stiffener direction has a much larger bending stiffness See Figure 5 21 for an illustration of a typical layered element consisting of a single plate layer and two stiffener layers eccentricities local z element plate seen from underneath Figure 5 21 A layered element consisting of a plate layer and two stiffener layers A stiffened plate consists of plate and stiffener layers The stiffe
221. ersion 7 1 PROPERTY LOAD load case RIGID BODY ACCELERATION RIGID BODY ACCELERATION GLOBAL iax lay iaz iarx iary iarz END ax jay az jarx ary arz PURPOSE The command defines an acceleration field The effect of this command may be compared with that of the GRAVITY load see the notes below but in addition to translational components the present command allows specification of rotational components The analysis program Sestra will compute the inertia load taking the volume of the elements and the material density into account Point masses will also contribute to the gravity load The rotational acceleration components refer to the axes of the cartesian coordinate system of the model PARAMETERS GLOBAL The cartesian coordinate system of the model is used ax ay az arx ary arz The acceleration components The unit of the rotational acceleration is radians second iax iay iaz iarx iary iarz Imaginary acceleration components Entering END implies that the load is real NOTES The following example is included as an illustration of the effect of the RIGID BODY ACCELERATION load type compared with the GRAVITY load type The accelerations given for the RIGID BODY ACCELERATION are in effect applied to the fixed nodes of the model Therefore the following two loads will produce the same results as illustrated for a simple canti lever beam in Figure 5 42
222. es may be done by dragging a rubberband Use the PROPERTY MATERIAL command to define the steel material properties see Figure 3 4 for data Give a name limited to 8 characters to the material Use the CONNECT MATERIAL command to assign the named steel material to all surfaces the plates and all lines the girders c se the SET ELEMENT TYPES command to assign element types to geometry the subsequent MESH command creates the actual elements First assign element type to surfaces All surfaces shall be assigned the 4 node shell SHELL 4NODES Then assign element type to lines Lines where there are girders see Figure 3 4 shall be assigned 2 node beam BEAM 2NODES Use the PROPERTY SECTION command to define the girder cross section see Figure 3 4 for data Give a name limited to 8 characters to the section Use the CONNECT SECTION command to assign the named cross section to all lines the assignment will only take effect for lines for which a beam element type has been assigned Use the PROPERTY ECCENTRICITY BEAM command to introduce eccentricities offsets for lines where there are girders By default the neutral axis of a beam element extends from node to node and coincides with the middle surface of a plate element But girders are welded onto the plates All beam elements therefore require an eccentricity of half the plate thickness plus half the girder height Rather than giving these eccentricities manually use the C
223. eseseeeeeee ener nennen 2 9 2 1 5 Constraints on Names niece een oe en re POUR RR RUGERTUGRE S e RETE NEM ERES 2 11 Mass Modellimg 5 5 2 rtp e rare ee Qe o e a tiri Der HP Pr gd 2 11 Other Properties tote cue ede Re I ee eta Praese oe eee dedu E a eue eerta 2 12 Transformations and Coordinate Systems essere enne nennen 2 12 Auxiliary Features iul ee ert o tbe a E Pe e Tete doit ered 2 13 Short Description of Commands sess eene enne enne nennen eene nnne nennen 2 13 Transfer of the FE Model through the Input Interface File seen 2 15 2 13 1 Writing and Optimising the Input Interface File esee 2 15 Interaction with other SESAM Programs sesssssseseeseeer eene enne nnne nnr enn nennen 2 16 3 1 3 2 3 3 34 3 5 3 6 3 7 3 8 3 9 USER S GUIDE TO PREEBENWNL 2 3250 652350 6d exe saa a ep n dae ped dodo iua saab daas eno poa dr oa deiodse 3 1 Getting Started the Graphical User Interface sess eene 3 2 Tutorial in Midship Section Modelling sss eene nennen 3 7 Geometry Modelling eene ere e e tr carre eee dk ertet E eee eso 3 15 3331 Defining Geometry 5 ette ede ea tec teret eise dT cedet ted RD TA REN dude 3 16 3 3 2 iDefmmg Slidpes ec e ete Hte e He TANE AE CERE ELA E PR Pes 3 23 3 3 3 Copying Geomietry i ee e e P debere desee teta ete ln FR Peer aad 3 24 3 3 4 Cutline Geometry eee l
224. esh corners and not mesh corners in corresponding positions This means that if say two lines of the bottom surface correspond to one line of the top surface then there must be a not mesh corner in between the two lines of the bottom surface See Figure 3 18 The element mesh for a body must also be prismatic i e the meshes of the top and bottom surfaces must in terms of topology be equal their corresponding borderlines curves must have equal number of ele ments and they must have mesh corner and not mesh corner in corresponding points Further the mesh of the side surfaces must be regular with no mesh refinement and with mesh corners in the four points connecting with the top and bottom surfaces and only there For solid models with several bodies it is advisable to have the bodies positioned so that the surface being the top of one body is the bottom of the next body and let the bodies be located side by side Otherwise meshing the bodies may be difficult PARAMETERS name User given name of the body top Name of the surface defining the top of the body bottom Name of the surface defining the bottom of the body side Side surfaces given in sequence until the body is closed Each surface given must adjoin the previously given side surface NOTES See also the DEFINE PRISM command Prefem SESAM 5 60 01 JUN 2003 Program version 7 1 DEFINE COORDINATE SYSTEM CYLINDRICAL start xyz z axis xyz r axis xyz COORDINATE SY
225. essor then you may need to limit each plot file to a single plot This command has the same effect as the SET PLOT FILE command Choose between various graphic presentation modes for ele ments etc See separate explanation of the command Set automatic display of geometry selected within a PROPER TY command With this switch ON the geometry will be dis played with dotted lines when hitting carriage within a PROPERTY command at the point where geometry is to be se lected Then selecting geometry and hitting carriage return will highlight the geometry selected by solid lines The command has no effect for the graphical user interface in which case colour highlighting is used for the same purpose Choose between GLOBAL AXES and SCREEN AXES for the ROTATE command The x axis of the SCREEN AXES is horizontal and pointing to the right while the y axis is vertical and pointing up By default GLOBAL AXES are used Determine manually by which scale the model is displayed The AUTO option will calculate a scale that independent of the viewing direction best adapts the display to the available plot ter screen area If a zoomed in or out view is shown the AUTO option will return to fitting the complete model into the screen area the same is achieved by the ZOOM OFF com mand To determine a user specified scale of reasonable magnitude notice that by entering the SET GRAPHICS SCALE command the program will give as default value for the
226. explained by Figure 5 16 twist angle The maximum twist angle allowed plane through nodes 1 2 and 4 Figure 5 16 Twist of element SESAM Prefem Program version 7 1 01 JUN 2003 5 45 CHECK MESH TOPOLOGY MESH TOPOLOGY select geometry PURPOSE The command performs a check on whether it is possible to create a mesh for the geometry The mesh is not created Creating large and complex meshes may be time consuming This command allows checking the consist ency of the data determining the mesh without the risk of wasting time Geometries that cannot be meshed will be reported allowing the user to adjust the data determining the mesh See Section 2 7 3 for constraints on the mesh PARAMETERS select geometry Surfaces and bodies for which a check shall be performed See Section 5 1 on how to perform a selection Prefem SESAM 5 46 01 JUN 2003 Program version 7 1 CHECK NON REGULAR NODES NON REGULAR NODES select geometry PURPOSE The command identifies surfaces with potential for mesh improvements The command enables the user to evaluate a quality aspect of the mesh based on the concept that a topolog ically square regular mesh is generally better than a non square one The command considers the corner nodes of quadrilateral elements A node is termed regular if there are 4 elements connected to it otherwise it is termed non regular A mesh that is not topologically square w
227. f surface name to be set to mesh corner or not mesh corner Close the list of points by en tering END NOTES The SET MESH PARAMETERS MAX MESH CORNER ANGLE command allows overruling the setting of mesh corner See this Prefem SESAM 5 244 01 JUN 2003 Program version 7 1 SET MESH PARAMETERS FINE COORDINATE FINENESS NORMAL COARSE MESH PARAMETERS MAX MESH CORNER ANGLE angle ON OPTIMIZE TRIANGLES OFF SOLID ELEMENT SHAPE sol shape param SURFACE ELEMENT SHAPE surf shape param PURPOSE The command sets parameters for the FE mesh creation The parameters are not stored on the model file and are general parameters i e not associated with individual surfaces or bodies OPTIMIZE TRIANGLES is the only parameter affecting the mesh topology The other parameters only affect the calculation of the nodal coordinates and only in the event of irregular element meshes These mesh parameters will influence the mesh created in a way that is not always easy for the user to fore see And changing the parameters will only to a limited degree improve a bad mesh However the parame ters may be used as follows delete the bad mesh change a parameter re create the mesh and visually check the result PARAMETERS COORDINATE FINENESS FINE NORMAL COARSE MAX MESH CORNER ANGLE angle OPTIMIZE TRIANGLES ON OFF Set the required degree of accuracy for the nodal coordinate calculation
228. face is cut in two Element type is inherited from the original surface See the COPY command for other properties carried over from the original surface plane shape New points are positioned where the plane cuts the borderlines of the surface The borderlines are cut as described above for line cut by point A new line is cre ated between the two new points The surface being cut is handled as described above for surface cut by line See also the SET NAMING CUT command Prefem 5 56 SESAM 01 JUN 2003 Program version 7 1 DEFINE DEFINE ARC BODY COORDINATE SYSTEM DAMPER INTERSECTION LAYERED LINE MASS ELEMENT NODE LINE PARAMETER POINT PRISM ROUNDED CORNER SECTOR CORNER SET SHAPE SPLINE SPRING SURFACE TRANSFORMATION PURPOSE The commands define geometry shapes tools for defining geometry transformations and coordinate sys tems sets and certain element types springs dampers etc PARAMETERS ARC BODY COORDINATE SY STEM DAMPER Define the geometry entity line curve of type arc Define the geometry entity body Define a coordinate system Define the element type damper SESAM Program version 7 1 INTERSECTION LAYERED LINE MASS ELEMENT NODE LINE PARAMETER POINT PRISM ROUNDED CORNER SECTOR CORNER SET SHAPE SPLINE SPRING SURFACE TR
229. ferent cross section types pipe I L etc In addition a general type section can be defined by entering the cross sectional area moments of inertia sectional moduli etc The local x axis of beam and truss elements always follows the neutral axis of the element In Figure 5 45 through Figure 5 53 the x axis is directed into the paper plane The local y and z axes are determined by the PROPERTY LOCAL COORDINATE BEAM command PARAMETERS section name BAR BOX CHANNEL DOUBLE BOTTOM GENERAL I L PIPE UNSYMMETRICAL I Cross section name Assigned to the appropriate beam and truss elements by the CONNECT SECTION command Define a bar cross section Define a box cross section Define a channel cross section Define a double bottom cross section Define a general cross section Define an I or H cross section Define an L cross section Define a pipe cross section Define an un symmetrical I cross section Prefem SESAM 5 190 01 JUN 2003 Program version 7 1 NOTES The effect of curvatures of inner corners of the cross sections are not taken into account in the calculation of the sectional properties torsional moment of inertia Note that the dimensions of a cross section should not be such that the chosen cross section degenerates into another type The formulae used for calculating the sectional properties are based on the assumption that the cross sections have reasonable shapes Generally the sectional modu
230. ffers him all features needed and is the most consistent approach A transformation is composed of any combination of Translations Rotations Scaling Mirroring Prefem SESAM 3 68 01 JUN 2003 Program version 7 1 Note For a transformation composed of more than one of the elements above the order is generally of consequence a translation followed by a rotation is different from the same in reversed order Transformations are first defined and given names Thereafter they are ready for use For defining boundary conditions and loads in a transformed inclined coordinate system Fororientating spring to ground and damper to ground elements For copying geometry Note When referring to a transformation in the definition of a load then only the rotational and mirror parts of the transformation are relevant If the same transformation is used for defin ing a boundary condition and orientating spring and damper elements then only the rotational part is relevant Translations and scaling are only relevant when the transformation is used for copying geometry Figure 3 20 shows an example of copying geometry by use of a transformation Example 3 9 shows how a load may be defined in a transformed coordinate system Example 3 9 Defining a Load in a Transformed Coordinate System A transformation named TR1 is defined as a 30 rotation about an axis going through the points P1 and P2 The global coordinate system X Y Z multipl
231. g thickness plus anisotropic material properties for each layer PARAMETERS ql q2 q3 Components of a vector Q in the cartesian coordinate system of the model deter mining by its projection onto the element plane the first material axis of the aniso tropic material Note that the vector Q cannot be perpendicular to any of the elements rho Material density nlay Number of layers of a multilayered sandwich material If nlay 1 then the element reduces to an ordinary shell element with anisotropic material properties thick Thickness of the layer in percent of the total element thickness as defined by the PROPERTY THICKNESS command If nlay 1 then this entry is skipped and the layer constitutes 100 of the total thickness For the last of several layers this entry is skipped as the thickness of the last layer will be equal to the remainder of the total thickness angle Angle in degrees from the projection of the vector Q to the first material axis of anisotropy for this layer Positive angle is positive rotation about local z axis dll d55 Terms of the lower triangular part of the general anisotropic elasticity matrix see Equation 5 4 Prefem SESAM 5 180 01 JUN 2003 Program version 7 1 damp damp2 Specific damping coefficients for the first and second material axes of anisotropy alphal alpha2 Thermal expansion coefficients for the first and second material axes of anisotropy laii i d21 d22 d31 d32 d33 The lower tri
232. g to many geom etry names A wild card name is a string with the character amp in addition to letters and digits A wild card name matches a name when only the character amp is a mismatch with the name Trailing amp s e g AP amp amp amp can be replaced by a e g AP which matches any number of characters at the end of a name alone therefore matches all names It is usually more efficient though to use the alternatives ALL POINTS INCLUDED etc rather than Even when not using the GENERATE command the user may find it useful to adopt a naming scheme simi lar to that of GENERATE see Section 3 3 7 as this will both enable use of the wild card concept and make it easier to identify the different parts of the geometry model Whenever geometry is to be selected it is possible to use wild card for the selection Wild card may in cer tain cases also be used when defining geometry Wild card used in connection with both selection and defi nition of geometry is exemplified by the following COPY command COPY A amp 1 amp amp 2 B TRANS This command will copy all geometry names starting with A and having 1 and 2 in the specified positions These geometries and those needed for the definition of these geometries are all copied The resulting geometries will be named B amp 1 amp amp 2 A non systematic naming of geometry may result in naming conflicts For example if a line included in the selectio
233. ge of the GENERATE command you basically first need to decide what the desired geometry model should look like i e where all points lines and surfaces should be Refining and adjusting the geometry model after giving the command is highly relevant but the major part of the geometry should be in place Used in this way the GENERATE command is extremely powerful The examples of Figure 3 24 through Figure 3 26 illustrate this top down approach to modelling The EXTRUDE command is based on first creating a typical section of the desired geometry model and thereafter extruding this to form a more complete model I e you start by creating a simplified model and then build on this one to establish the complete model The tutorial example of Section 3 2 illustrates this bottom up approach to modelling 3 3 10 Importing DXF File The READ DXF command will read a DXF formatted file DXF is a format for exchanging 3D CAD data DXF originates from the CAD program AutoCAD Based on the information in the file Prefem will estab lish a geometry model This model may be extended and modified A DXF file may contain several types of information of which Prefem will interpret a selection as described in Chapter 5 3 3 11 Geometry Names Adopting a systematic convention for naming the geometry will ease both modelling and later interpretation of the geometry model The user is advised to decide a naming convention prior to commencing the model ling The nam
234. ged and a display of the new loads is desired by ADD DISPLAY this command is required The command is not required prior to the WRITE command to get the correct loads on the Input Interface File re displays geometry or FE mesh to get a display with current setting of labels etc reads either an Input Interface File for displaying only no modifications may be done or a DXF file a geometry model is established based on the information rotates the display on the screen sets various control and performance parameters writes the current model onto an Input Interface File zooms in and out on the screen display reads a given number of commands from a command input file into Prefem SESAM Prefem Program version 7 1 01 JUN 2003 2 15 DELETE deletes geometry FE mesh properties one node elements transformations EXIT involves exiting from Prefem The model and log files are closed and saved 2 443 Transfer of the FE Model through the Input Interface File As is the case for all SESAM preprocessors the model created by Prefem is transferred to the hydrodynamic and or structural analysis programs via the Input Interface File which forms a part of the SESAM Interface File system The Input Interface File the T file is a sequential ASCII character file with 80 character long records The straightforward definition of the file enables external programs to be connected to the SESAM system with comparative ease One interface file w
235. gging a rubber band rectangle using the LMB Polygon selection Position the cursor and press the shift key to define the first polygon point While keeping the shift key pressed repeatedly move the cursor and click the LMB to make a polygon Release the shift key and click to define the last polygon point A straight line between the first and last polygon points closes the polygon If the LMB is pressed rather than clicked a rubberband line appears as an aid to determine the position of the polygon segment Apply the above graphical selection methods as follows Select a point and line curve by the item itself or its label SESAM Prefem Program version 7 1 01 JUN 2003 3 61 Select a surface by rubberband polygon around it or by clicking its label You may also use the right mouse button RMB and left mouse button LMB in combination as follows Click the RMB once ona borderline curve of the surface and see that the line curve is highlighted changing colour Without moving the mouse click the RMB once more and an adjoining surface is highlighted If this is the desired surface then click the LMB If not then keep clicking the RMB until the desired surface is highlighted whereupon the LMB is clicked Note that all clicks with the RMB and LMB should be done without moving the mouse or at least not more than a set fractional distance Select a body in the same way as explained above for a surface When the RMB is repeatedly clicked and
236. given in Manager Af ter a rotation of the model the viewpoint will return to this de fault viewpoint when the command SET GRAPHICS EYE DIRECTION DEFAULT is given or the Direct access button Default is clicked X Y and Z components of the direction to the eye Choose linear dependency mode i e whether independent nodes must be super or not See Section 3 5 8 for an explana tion Independent nodes that are not already super are forced to be come super Independent nodes need not be super A default local coordinate system for beam elements is given This default is valid for subsequently created lines Note Even without use of this command default local coordinate systems will be assigned to beams This default corresponds to the setting of the command SET DEFAULT LOCAL COORDINATE BEAM ZX PLANE ZX PLANE Note Copied lines will inherit the setting of the original Le the setting of this command will not apply Note The default set by this command is overruled by explicit assignment using the PROPERTY LOCAL COORDINATE BEAM command Prefem 5 218 NONE YX PLANE ZX PLANE MATERIAL material name MAX ELEMENT LENGTH length NUMBEROF ELEMENTS nelm SECTION section name SESAM 01 JUN 2003 Program version 7 1 Any previously given default setting for local coordinate sys tem for beams is annulled The local yx plane is used for determining the local coordinate system The command
237. given name of the arc The name is used for later reference to the line e g when a surface is defined start point Name of the point defining the start point of the arc end point Name of the point defining the end point of the arc centre point Name of the point being the centre of the arc nelm Number of elements to be created along the arc See also the commands SET NUMBEROF ELEMENTS and SET MAX ELEMENT LENGTH NOTES The direction of the arc going from start point to end point has consequence for the local coordinate system of beam elements Figure 5 18 Arc SESAM Prefem Program version 7 1 01 JUN 2003 5 59 DEFINE BODY BODY name top bottom side PURPOSE The command defines the geometric entity body Bodies are by definition enclosed by top and bottom surfaces and by any number of side surfaces The fol lowing requirements to a body and its mesh must be met e A body must logically if not geometrically be prismatic as shown in Figure 3 18 This implies that the side surfaces must be quadrilateral if not rectangular and extend from the top sur face to the bottom surface In the command defining bodies the side surfaces must be given in sequence The top and bottom surfaces must have been defined in the same sequence starting and ending in corre sponding positions The number of borderlines of the top and bottom surfaces need not be the same but the surfaces must have m
238. gram version 7 1 01 JUN 2003 5 33 CHANGE NAME NAME select geometry new names PURPOSE The command changes the name of selected geometry PARAMETERS select geometry Select geometry to be renamed See Section 5 1 on how to perform a selection new names The new name of the selected geometry If more than one geometric entity has been selected either by use of parentheses or wild card selection then wild card con struction of the new names must be used EXAMPLES The following command will change the names AP111 to BP111 and AJ111 to BJ111 CHANGE NAME AP111 AJ111 B The following command will change all names starting with A to corresponding names starting with B CHANGE NAME A B Prefem SESAM 5 34 01 JUN 2003 Program version 7 1 CHANGE NODE NODE node number x y z PURPOSE The command changes the coordinates of a node The shape of the adjoining elements will consequently change PARAMETERS node number Number of the node X New X coordinate The old coordinate is used as the default value y New Y coordinate The old coordinate is used as the default value Z New Z coordinate The old coordinate is used as the default value NOTES This command can only be performed after creating the mesh If the mesh is deleted and recreated then the result of a CHANGE NODE command is lost If variable thickness of surfaces is defined then the PROPERTY THI
239. gram version 7 1 01 JUN 2003 APPENDIX B 21 Hence M 10000 100 kg 10 kg So our fundamental units are M in 10 kg Lincm Tins The next step is to determine the density Young s modulus etc in terms of our fundamental units Steel density p Density Mass Volume M L thus the derived density shall be in 10 kg cm Psteel 7850 kg m 7 85 10 10 kg cm Young s modulus E Young s Modulus Force Area M L T L M L T y thus the derived Young s modulus shall be in 10 kg cm s E 2 1 10 N m222 1 10 kgm s m 2 2 1 10 kg m s Then in our derived units E 2 1 101 109 100 10 kg cm s 2 2 1 10 10 kg cm s Gravity Gravity Acceleration L T thus our derived gravity unit shall be cm s g 9 81 m s 9 81 10 cm s 981 cm s Sea water density Density Mass Volume M L thus the derived density shall be in 10 kg cm Pwater 1025 kg m 1 025 10 10 kg cm B2 2 Consistent Sets of Units Tables over sets of consistent units are provided below Nomenclature cm centimetres E Young s modulus kg kilograms kgf kilograms force L fundamental length symbol m metres Prefem APPENDIX B 22 01 JUN 2003 SESAM Program version 7 1 mm millimetres fundamental mass symbol N Newtons S seconds t tonnes tonnef tonnes force T fundamental time
240. he PROPERTY MATERIAL command PARAMETERS ONE NODED Define a one node mass element mass element name User given name of the mass element select points Select points where one node mass elements are to be connected See Section 5 1 on how to perform a selection material name Name of a previously defined material of type mass GLOBAL The masses given in the PROPERTY MATERIAL command refer to the cartesian coordinate system of the model TRANSFORMED The masses refer to a transformed coordinate system trnam Name of the transformation used AT POINT The mass is positioned at the point ECCENTRIC The mass is given an eccentric position with respect to the point XyZ Eccentricity vector from the point to the mass Prefem SESAM 5 70 01 JUN 2003 Program version 7 1 DEFINE NODE LINE next point END NODE LINE name start point PURPOSE The command defines the geometric entity node line This is a line where a node is to be created at every point given and no nodes in between these points The command is used when the position of all boundary nodes including mid side nodes for higher order elements is to be explicitly positioned The actual nodes are defined by using the MESH command PARAMETERS name User given name of the node line start point Name of the point defining the start point of the node line next point Name of the points defining the node line When the last point has
241. he complete model as a second level superelement when linear dependencies have been defined in this way Either of Sestra s equation solvers Multifront and Supermatrix may be employed The independent d o f may have any boundary condition i e it is not required to be superl as in the other alternative This alternative is chosen by giving the command SET DEFAULT LINEAR DEPENDENCY MODE NO FORCE TO SUPER prior to the PROPERTY LINEAR DEPENDENCY command Also this alternative requires use of the Multifront equation solver in Sestra Note The independent node or d o f cannot be linearly dependent of another node or d o f 3 5 0 Point Mass Point masses are defined by the PROPERTY POINT MASS command Such a mass will contribute to the mass matrix as a diagonal mass matrix as opposed to the mass element which is comprised of a full mass matrix 3 5 10 Numeric Value Input Numeric values need to be given for most properties In most cases only constant values are accepted Alter natively to giving these constant values as single real or integer values many of them can be given as real expressions In such cases the program prompt will be real expression Examples of real expressions are e 03 11 e 4 15 2 e PI 2 However in the case of surface thickness and loads see Section 3 6 variable values may optionally be given as functions see Section 3 7 3 6 Defining Loads Loads are defined by the PROPERTY LOAD c
242. he file you should check the appropriate box prior to starting Prefem The Input Interface File is then automatically written when you exit Prefem using the command EXIT This makes the Prefem command WRITE superfluous Note If you in Windows close the Prefem window by the X in the upper right corner or by the Close AIt F4 command of the window menu then the Input Interface File will not be written even though you have requested this when starting Prefem This feature may be used if you change your mind and decide not to write the file after having started Prefem SESAM Prefem Program version 7 1 01 JUN 2003 5 99 EXTRUDE First select geometry to copy and geometry to extrude for each give a prefix for geometry names created EXTRUDE geometry to copy copy prefix geometry to extrude extrude prefix Secondly select the global cartesian or a specified cylindrical coordinate system for the operation GLOBAL CYLINDRICAL orig x orig y orig z zaxi x zaxi y zaxi z_ raxi x raxi y raxi z Thirdly give the number of copies extrusions to make and the vectors defining the copy extrude process i dx dy dz REPEAT n times L p n copy extrude dphi END Finally choose only copying or also extruding and if extruding what to extrude COPY ONLY POINT TO LINE LINE TO SURFACE SURFACE TO BODY
243. he global axes either in positive or in negative direction the GLOBAL INFINITY options The guiding point will lie in the y x or z x plane on the positive y or z side respectively This is however not true for the FROM FIXED POINT alternative which involves that the guiding point lies on the negative y z side SESAM Prefem Program version 7 1 01 JUN 2003 5 171 For two node beam elements the local coordinate system is constant along the local x axis For three node beam elements the local coordinate system may differ between the three nodes The local x axis will be tan gential to the parabola through the three nodes Beam elements for which local coordinate systems are not explicitly defined will be given default local coordinate systems as follows The local z x plane is parallel with the global Z axis and with the positive direction of the local z axis in the direction of the positive global Z axis as if the command PROPERTY LOCAL COORDINATE BEAM ZX PLANE Z GLOBAL INFINITY was given If the local x axis is parallel with the global Z axis then the local z axis is defined to be parallel with the global Y axis The local coordinate systems of the elements can be tabulated by the PRINT ELEMENT select element LOCAL COORDINATE command The right hand column of this print table indicates whether the local coordinate system has been explicitly defined SPEC or calculated by the default condition described above CALC PARAMETERS
244. he parame ters SHARY modified SHARY program sfy SHARZ modified SHARZ sfz program SESAM Prefem Program version 7 1 01 JUN 2003 5 199 PROPERTY SECTION section name L POSITIVE NEGATIVE L hz ty by tz sfy sfz PURPOSE The command defines an L cross section hz shear centre y tz ty y Negative Positive Figure 5 51 L section PARAMETERS hz Height ty Thickness of web by Width of flange tz Thickness of flange sfy sfz Factors modifying the shear areas calculated by the program The modified shear areas are see the PRINT SECTION com mand for an explanation of the parameters SHARY a SHARY program SfY modifie SHARZ modified SHARZ program sfz POSITIVE NEGATIVE Web location in the local y direction Prefem 5 200 SESAM 01 JUN 2003 Program version 7 1 PROPERTY SECTION section name PIPE PIPE dy sfy sfz PURPOSE The command defines a pipe cross section PARAMETERS dy t sfy sfz dy Figure 5 52 Pipe section Outer diameter Thickness of wall Factors modifying the shear areas calculated by the program The modified shear areas are see the PRINT SECTION command for an explanation of the parame ters SHARY a SHARY program SfY modifie SHARZ modified SHARZ sfz program SESAM Prefem Program version 7 1 01 JUN 2003 5 201 PROPERTY SECTION section name UNSY
245. hear centre location z component Static area moment about y axis Static area moment about z axis Prefem SESAM APPENDIX B 2 01 JUN 2003 Program version 7 1 CY Centroid location from bottom right corner y component CZ Centroid location from bottom right corner z component Variables other than the ones above are only temporary Note The local x axis of the beam or truss element goes through the centroid of the cross section I e the nodal displacements and consequently the cross sectional constants above refer to this axis The torsional moment of inertia however refers to the shear centre In most beam element theories the torsional d o f is not coupled to the transverse d o f s Therefore when torsion is of importance the shear centre should not be located far away from the centroid of the cross section i e avoid heavily unsymmetrical cross sections SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX B 3 B1 1 Bar section B 1 1 1 Sectional Dimensions AZ Height BB Width at bottom BT Width at top SFY Shear factor y direction SFZ Shear factor z direction BB Figure B 1 Bar section B 1 1 2 Sectional Parameters Computed The expressions below for LX IY IZ WXMIN WYMIN WZMIN SHARY and SHARZ are taken from Ref 1 The expressions for SHCENY and SHCENZ are taken from Ref 3 A BT BB 2 H HZ BB 44 3 BB BT D HZ H B BT 2 A D HZ BM 2B HZ HZ A AREA BB BT HZ 2 Prefem
246. hod is the quicker one as the data is given on the fly Practical and efficient use of the COPY command will benefit by an understanding of the concept of wild cards see Section 3 9 3 as well as the notes below for information on this PARAMETERS select geometry mask trnam TRANSLATION VECTOR REPEAT n times dx dy dz NOTES Select geometry to be copied Copying a body implies copying of the related surfaces lines and points as well Copying a sur face implies copying the related lines and points etc See Sec tion 5 1 on how to perform a selection Mask name a wild card name for naming the new geometry See the notes below Name of the transformation defining the copying process This transformation must previously have been defined by the DE FINE TRANSFORMATION command Copy by means of a translational vector Make several copies by repeating the translational vector This is optional simply skip REPEAT n times and give the vector dx dy dz directly if a single copy is wanted Number of copies The translational vector Normally several geometric entities are copied by a single COPY command A system for naming the new geometric entities is therefore required The mask name provides this system as follows Wild card characters amp and integrated into the mask name implies that the corresponding characters in the names of the new geometry are the same as those in the names of the or
247. ical means clicking and dragging the mouse as explained in Section 3 9 1 In the command description the texts select geometry select bodies select surfaces select lines and select points should be understood as the following command syntax name of geometry ALL POINTS INCLUDED ALL LINES INCLUDED ALL SURFACES INCLUDED ALL BODIES INCLUDED GEOMETRY OF ELEMENT element SESAM Prefem Program version 7 1 01 JUN 2003 5 3 name of geometry EXCLUDE INCLUDE ALL POINTS INCLUDED ALL LINES INCLUDED ALL SURFACES INCLUDED ALL BODIES INCLUDED GEOMETRY OF ELEMENT element MATERIAL material name SECTION section name WITH e THICKNESS lowthick highthick END PARAMETERS name of geometry Name of the geometry to select May also be a wild card selec tion see Section 3 9 3 and name of a pre defined set see Sec tion 3 9 4 ALL POINTS INCLUDED All points of the geometry model are selected ALL LINES INCLUDED All lines of the geometry model are selected ALL SURFACES INCLUDED All surfaces of the geometry model are selected ALL BODIES INCLUDED All bodies of the geometry model are selected GEOMETRY OF ELEMENT The geometry to which the given element belongs is selected the geometry name is logged on the command log file and Parentheses enable giving several entries Remember entering a space on both sides of the paren
248. ical or spherical coordi nate system will remain a curve in these systems after changing the coordinates of the start or end points SESAM Prefem Program version 7 1 01 JUN 2003 5 29 CHANGE ELEMENT ATTRIBUTE f MATERIAL material name ELEMENT ATTRIBUTE select geometry graphic select elem THICKNESS thickness PURPOSE The command changes thickness and material for selected elements While the normal procedure for assign ing thickness and material is to assign such attributes to geometry i e all elements within the selected geometry this command allows giving thickness material to specific elements within for example a sur face The procedure is as follows First select the geometry to which the elements belong the elements of the selected geometry are then displayed Then select elements using the graphic rubberband or polygon The selected elements are then dis played Finally modify the element thickness or material Note If the mesh is deleted and re created the changes will be lost The CHANGE ELEMENT ATTRIBUTE command must then be repeated Note Several geometric entities may be selected and the subsequent graphic selection may bridge these geometric entities Note Several surfaces overlapping in the display one behind the other may be selected for exam ple using rubberband followed by a rubberband polygon selection of elements The corre sponding elements in
249. ie a Reg do dea ta Saia 4 6 44 7 Background Execution utet RETREAT E Tene dein vuaeevs 4 6 4 1 8 Command Lane Argumerits rne inte ote eerte re Nen ete E M EA 4 7 Program Requirements ccccecccsssesscsescescecsececeeceeeeseesesecseecssessecseeceseeeseecsecesecsseseaeeeaeeneeeaeeeeeas 4 9 ADA Execution TIME usce note e aeoe ti etaed RENTE 4 9 422e StOTa eS Pacers vals cee sean ee e ncescdnadsudedednasduclosedeatcvedaanties uasstteths ated voeden Cols a a aeien 4 9 Pro gratin Limitations ikea eee nme ner te ERR OR INT saga duu ERIT RNC e n fr nene 4 9 COMMAND DESCRIPTION i ieeetescere iv nosmet ev oko Mo pu ecko So Pu aka geTe Pur bu io tas r bx P Ee E Mo dee vR ve gen 5 1 Selecting Geometkys adatti SR EE Done iter esie HER ee eee 5 2 Selecting Nodes and Elements 2 n err t ertet dete x A e el wi a eee eae 5 4 B nctolssontesemoev tS NL elm MAUI ed PN NL NEAL Ea cH E NN DA US 5 6 LINEAXRS2POINTS VAR Y ING vor orra duritie ntt Fasten ater RI FIERE aist 5 10 EINEAXR 3SPOINTS VAAR Y DING Luo rrearen aAa E aeaa ia s NIU REO RUN RUE 5 11 LINEAR RADIUS VARYIBNG corio DIU Ica MEE T DUM ON E a NOR 5 12 CYLINDRICAL ANGLE VARYING ehea E d DR A E NEE QUAM 5 13 CYLINDRICAL RADIUS VARYING 5i etecoi d ri a a ea iea aa 5 14 VALUE BETWEEN oiiaee aa s aaaea Ca TaS ana EE e cR Dr uo Roe Um TS 5 15 ONLY BETWEEN oeiee ia e A EA ty sews ded aE E end eae eva hte a dut 5 17 STING COS IN tert TT A E E E ER ope eee qe e irre aet ipe ec e RR ARS 5 18 EX
250. ied by this transformation yields the system XT Y p Z4 see Figure 3 59 A load may be defined in this transformed coordinate system as follows DEFINE TRANSFORMATION TR1 ROTATE ANGLES 30 P1 P2 PROPERTY LOAD TRANSFORMED TR1 Figure 3 59 Use of transformation for defining loads 3 11 2 Coordinate Systems The DEFINE COORDINATE SYSTEM command defines named coordinate systems for use in other com mands Any number of cylindrical and spherical coordinate system may be defined Relative to the cartesian coordinate system of the model the following data is given same as within the GENERATE command SESAM Prefem Program version 7 1 01 JUN 2003 3 69 Type of coordinate system i e CYLINDRICAL or SPHERICAL Theorigin of the cylindrical or spherical coordinate system Coordinates of a point determining the Z axis cylindrical or pole axis spherical Coordinates of a point determining the plane where 0 Coordinate systems are used For defining point coordinates By the GENERATE command note that the GENERATE command will unless referring to a pre defined coordinate system implicitly define a coordinate system For defining boundary conditions and loads Radial and circumferential boundary conditions are for example easily defined by referring to a cylindrical or spherical coordinate system A coordinate system may for example be used for specification of point coordinates as shown by the exam ple below
251. iffeners are modelled with proper spacing but not in their correct positions The display should be interpreted with this fact in mind The stiffeners of a layered element are displayed as follows SESAM Prefem Program version 7 1 01 JUN 2003 5 67 Ifthe stiffener spacing is greater than the dimension of the element in the spacing direction then one stiff ener will be displayed in the centre of the element If the stiffener spacing is smaller than the element then the proper amount of stiffeners is displayed with proper spacing The stiffener group will be centrally located on the element Figure 5 22 contains examples of layered element displays The SET GRAPHICS PRESENTATION LAY ERED ELEMENT SOLID SECTION command has been used 7s l proper spacin l sin gle layered Es C NM IESENE element seen several layered 1 a from underneath elements seen from underneath and above The two examples show how layered elements may be verified graphically ee ee The illustration to the left shows a single layered element with a spacing between the stiffeners smaller than the element dimension Therefore several stiffeners are pore displayed with the proper spacing Their exact positions however are not correct The two illustrations to the right show the same stiffened plate but the number of
252. iginals SESAM Prefem Program version 7 1 01 JUN 2003 5 49 Characters other than amp and in the mask name replace the corresponding characters in the names of the originals fa name for a new geometry constructed from the above rules is occupied then default names will be used POI PO2 for points LI1 LI2 for lines and SUI SU2 for surfaces A geometric entity not embraced by select geometry but forming a part of geometry that shall be copied will also be copied For example if line AI123 is defined based on point BP123 then copying A will also copy BP123 even though it does not match the mask name The mask name will apply to such extra geometric entities as well e g the mask name C for copying AI123 and BP123 will result in the new names CI123 and CP123 respectively If there already partly exists geometry at the destination of a copy then that part of the geometry will not be copied When copying geometry some properties and other data are carried over to the copy and some are not Below are listed the properties and other data carried over to the new geometry For points Boundary conditions Loads For lines Number of elements line division Element length ratio Maaterial property Section property Boundary conditions Loads For surfaces Material property Thickness Boundary conditions Loads For bodies Material propert
253. ill be created for each superelement The name of the file will be prefixT FEM where e prefix is an optional character string that may and may not include a directory specification the string is common for all superelements in a superelement model e T is a mandatory character identifying this as an Input Interface File a T file as opposed to a Loads Interface File L file which uses character L and a Results Interface File R file which uses character R P is the superelement number the identifier of the superelement e FEM is a mandatory file extension Normally the user may find it convenient to leave the prefix void This is also the default condition An example of a name of an Input Interface File is ABCTS FEM When using the superelement technique all superelements belonging to the same model should have the same file prefix If the above file superelement 5 is one of several files of a superelement model then all Input Interface Files should be named ABCT FEM where is the superelement number 2 13 1 Writing and Optimising the Input Interface File Whether or not to write the Input Interface File is normally controlled by Manager If you want to produce the file you should check the appropriate box prior to starting Prefem The Input Interface File is then auto matically written when you exit Prefem using the command EXIT This makes the Prefem command WRITE superfluous Note If you
254. ill have one or more non regular nodes See Figure 5 17 Regular nodes Non regular nodes Topologically square mesh Topologically and geometrically non square mesh Figure 5 17 Square mesh with only regular nodes and non square with non regular nodes Only elements of surfaces shell and membrane and only nodes in the interior of surfaces are considered The command will write a list of surfaces where there are elements with two or more non regular nodes In the example of Figure 5 17 there are two elements with two non regular nodes each Among the surfaces listed there may be some surfaces where a different setting of mesh corners or number of elements will give better mesh The total number of non regular nodes and total number of elements with two or more non regular nodes are also written PARAMETERS select geometry Surfaces for which a check shall be performed See Section 5 1 on how to perform a selection SESAM Program version 7 1 01 JUN 2003 CONNECT LAYERED layered name select surfaces CONNECT MATERIAL material name select geometry SECTION section name select lines PURPOSE The command connects assigns layered element material and cross sectional data to the relevant geometries The material and cross sectional data must previously have been defined by the PROPERTY MATERIAL and PROPERTY SECTION commands In order for an anisotropic material to be connected to a surface the s
255. in Windows close the Prefem window by the X in the upper right corner or by the Close AIt F4 command of the window menu then the Input Interface File will not be written even though you have requested this when starting Prefem This feature may be used if you change your mind and decide not to write the file after having started Prefem Prefem SESAM 2 16 01 JUN 2003 Program version 7 1 Also controlled by Manager is the optimization of the internal node numbering going from 1 to N where N is the number of nodes in the model in order to minimise the bandwidth of the stiffness matrix When checking the appropriate box prior to starting Prefem the auxiliary program Bpopt is automatically run after exiting Prefem Bpopt then optimises the internal node numbering and produces a revised Input Interface File Note Unless Sestra s Multifront equation solver is used the optimization should always be per formed or else the CPU time may be excessively large The Multifront equation solver is pres ently available for static analysis only implying that optimization should be performed for all dynamic analyses Moreover if the model created is a first level superelement which is to be coupled with other superelements then this optimization should be performed prior to reading the model into Presel If you run Prefem in a non standard way not using the command Model General Prefem in Manager you need to either use a command line argument see
256. ines DEFINE SURFACE S2 L1 L2 L3 The command below defines surface S3 bounded by the two unconnected lines L1 and L2 Unless already existing two straight lines with default names will be created between the end points of L1 and L2 DEFINE SURFACE 3 L1 L2 The command below defines surface S4 bounded by the lines curves L1 A2 L3 L4 and L5 By default all five points will be mesh corners see Section 3 4 1 for a description of the concept of mesh corners Reduce the number of mesh corners to the maximum allowable 4 by defining at least one of the points as a not mesh corner Figure 3 31 illustrates a mesh that may have been created for surface S4 DEFINE SURFACE S4 L1 A2 L3 L4 L5 SET MESH CORNER TYPE S4 P5 NOT CORNER END The two commands above may alternatively be substituted by the single command below DEFINE SURFACE S4 L1 A2 L3 L4 NOT MESH CORNER L5 ie eee LD a P SI eu L2 rd x Ec ET o AA P2 l gt dashed lines don t exist P4 X 12 x prior to surface L3 P3 definition L4 1 i P5 LII 3 LIO AD B5 e Figure 3 16 Defining surfaces Prefem SESAM 3 22 01 JUN 2003 Program version 7 1 The command below defines a surface bounded by three arcs As the arcs do not lie in a common plane the interior of the surface is not explicitly defined In this case the mesh iteration process will give a concave mesh as shown in the middle of Figure 3 17 See Section 3 4 5 for more information on meshes fo
257. ing convention employed by the GENERATE command see Section 3 3 7 may be used as a guide Also refer to Section 3 9 for a discussion on how a systematic convention for naming the geometry may be utilised for easy reference to several geometrical entities SESAM Prefem Program version 7 1 01 JUN 2003 3 35 3 4 Creating the FE Model Having defined the geometry plus additional data as described below the FE mesh is automatically created by the MESH command Finite elements may only be created on the appropriate type of geometry i e beam elements may only be created where there are geometry lines shell elements only where there are surfaces etc Figure 3 28 illus trates this principle Geometry FE mesh 4 points 4 lines 1 surface elements are shown in shrunken view shell elements are shaded as well mx beam elements Jj EM beam elements 7y along lines also internally NS on surface OA shell elements cannot be on surface created T YES NO if O Figure 3 28 Finite elements are only created on appropriate geometry The meshing is performed in the following sequence Beam or truss elements are created for lines curves if relevant If such elements are not requested then only discretisation data for determining the surface mesh is established Membrane or shell elements are created for surfaces if relevant If such elements are not requested then only discretisation data for determining the body mesh
258. ing to the line by referring to the transforma tion T1 T1 must therefore first be defined The string amp amp 2 in the COPY command specifies the names of the copies the two points and the line as follows The two ampersands amp amp involve that the two first characters of a copy name will be taken from its origin while the third character will be replaced by 2 See Figure 3 20 See Section 3 9 3 for information on the concept of wild cards DEFINE TRANSFORMATION T1 TRANSLATE DISPLACEMENTS 0 0 10 COPY LI1 amp amp 2 T1 When copying geometry some properties are carried over from the original to the copy and some are not See the description of the COPY command for more details on this SESAM Prefem Programversion7 1 OLJUN 2003 325 P11 LII Ar N P11 P21 LD P22 Figure 3 20 Example of use of the COPY command 3 3 4 Cutting Geometry The geometry model may be cut by the CUT command As illustrated in Figure 3 21 a surface S1 may in alternative ways be cut in two resulting in two new surfaces SUO and SUI a new line along the split and each of the two bounding lines cut in two as well The figure also illustrates how the command will attempt to distribute the number of elements set for lines according to where the lines are cut 1 define point Four alternatives for cutting p tool point line or surface CUTLINE GRAPHICS not illustrated PREDEFINED PLANE YZ PLANE dx GENERAL PLANE P1
259. ining geometry and for projecting FE mesh onto them In itself a shape does not constitute a part of neither the geometry model nor the FE model The DEFINE command is used for defining shapes The different shapes are given in table Table 3 2 and illustrated in Figure 3 19 Table3 2 Shapes and their definitions Shape Definition Plane Three points Sphere One point and radius Cylinder Two points and radius Cone Two points and two radii Prefem SESAM 3 24 01 JUN 2003 Program version 7 1 Figure 3 19 Shapes Section 3 3 1 includes a few examples of use of shapes for defining geometry 3 3 3 Copying Geometry Copying geometry is performed by the COPY command and referring to transformations defined by the DEFINE TRANSFORMATION command The following types of transformation may be defined Translation Rotation Scaling Mirroring A transformation may also be a combination of these Be aware of that the order of the transformations gen erally is of consequence A translation followed by a rotation is in general different from the same rotation followed by the same translation See Section 3 11 1 for more information on transformations Any defined point line surface or body can be copied using the COPY command The command specifies the geometry to be copied the name of the copy and the transformation defining the copying process The command below copies the line LI1 plus the points belong
260. ints The DEFINE MASS ELEMENT command enables definition of mass elements full mass matrices for selected geometry points The CHANGE PROPERTY or PROPERTY CHANGE LOAD load case TO MASS command enables conversion of selected load cases for selected geometry points lines to node masses This is relevant for the following load types CONCENTRATED in general independent of type of element BEAM CONCENTRATED LINE LOAD and PART LINE when applied to 2 node beam elements 2 9 Other Properties In addition to defining material data beam cross sections etc as described in Section 2 6 the PROPERTY command is used for defining properties like Local coordinate systems for Beams Surface elements only relevant for layered elements Eccentricities for beam elements Linear dependencies by which one or more degrees of freedom or nodes may be made linearly dependent of one or more other degrees of freedom or nodes Initial displacements and initial velocities this is relevant in connection with dynamic analysis 2 10 Transformations and Coordinate Systems Transformations and coordinate systems are defined by the DEFINE command for various purposes Both are first defined and given names and are then available for later reference Transformations composed of translations rotations scaling and or mirroring are used For defining boundary conditions and loads in a transformed askew coordinate system
261. ion of any current mesh and re creation of a new mesh if possible The new mesh will automatically be displayed provided that there was a mesh before the change and that this was displayed Prior to changing relative sizes of elements along lines curves SET ELEMENT LENGTH RATION however any current mesh must be deleted DELETE MESH ALL The command CHANGE NODE allows giving new cartesian coordinates for a node Note however that this modification will be lost once the mesh is deleted and a new mesh created The MESH ADJUST command will change the element discretisation so that all surfaces can be meshed The SET DEFAULT ADJUST MESH command or pressing the Shortcut command Mesh adj sets a mode in which the MESH ADJUST command is automatically executed whenever the element discretisa tion is changed 3 5 Defining and Assigning Connecting Properties Material data beam cross sections plate thicknesses boundary conditions loads etc are so called proper ties that are assigned or connected to the relevant geometry by referring to the appropriate geometry names The properties will automatically be transferred to the FE model The command for defining properties is PROPERTY The various properties are discussed in the subsections below The property types load ini tial displacement and initial velocity however are discussed in Section 3 6 And the property type trans formation is discussed in Section 3
262. ior of a surface will not be explicitly described A shape may then be used to define the interior by projecting the surface onto the shape for example a sphere or a cylinder Thus the border of a surface is defined by its borderlines and curves while its interior is defined by a shape See Section 3 3 2 on shapes and Section 3 4 5 on element meshes for curved surfaces A surface may be defined by selecting any number of points on its border and concluding the list of points either by END or by closing the surface by repeating the first point selected Straight borderlines with names SESAM Prefem Program version 7 1 01 JUN 2003 3 21 LIO LI1 LI2 etc will automatically be created where there are no lines The command below defines sur face S1 Note that a straight line will be created even in cases where a curve e g an arc instead of a line has already been defined this may not be what the user wants To avoid this pitfall and also to have full control over the line names define the lines curves explicitly and thereafter define the surface by referring to the lines curves instead of the points see the next example defining surface S2 DEFINE SURFACE S1 P1 P2 P3 END The above is equivalent to DEFINE SURFACE S1 P1 P2 P3 P1 The command below defines surface S2 bounded by the lines L1 L2 and L3 The program will automati cally detect that the three lines enclose a surface L3 joins L1 and will therefore not request or expect more l
263. irst copy extrusion 2 for the sec ond and so on m is a counter Lines are named prefixLnm Surfaces are named prefixSnm Bodies are named prefixBnm Prefem SESAM 5 102 01 JUN 2003 Program version 7 1 GENERATE First specify the level of the geometry to generate and give the id of geometry names BODY SURFACE GENERATE BY NAME id LINE POINT Specify the topology space i e the number of points in the three topological directions K start K end K step K el J start J end J step J el I start I end I step I el END END Choose the type of coordinate system to use in the geometry generation coord name CARTESIAN CYLINDRICAL SPHERICAL orig x orig y orig z zaxi x zaxi y zaxi z_ raxi x raxi y raxi z Give the starting point for the generation i e coordinates of the first point x0 yO z0 Give the vectors for mapping the I topology into the geometrical coordinate system dxI dyI dzl END REPEAT n times Gi ve the vectors for mapping the J topology into the geometrical coordinate system dxJ jdyJ dzJ END REPEAT n times Gi ve the vectors for mapping the K topology into the geometrical coordinate system dxK dyK dzK END REPEAT
264. irst point defining the axis axis 2 Name of the second point defining the axis point 1 Name of the first point defining the linear value value 1 Value in the first point point 2 Name of the second point defining the linear value value 2 Value in the second point Example of use see Figure 5 9 CYLINDER ANGLE VARYING AP1 AP2 P1 3 9 P2 2 1 P1 defines a radial plane T P2 defines a radial plane ia 1 The function varies with the angle but is constant in a radial plane lt AP and AP2 define the axis Figure 5 9 Example of use of CYLINDER ANGLE VARYING function Prefem SESAM 5 14 01 JUN 2003 Program version 7 1 CYLINDRICAL RADIUS VARYING CYLINDER RADIUS VARYING axis 1 axis 2 point 1 value 1 point 2 value 2 PURPOSE The command defines a value varying linearly with the distance from a given axis The value is specified in two points One of the points can lie on the axis The value will be constant on any cylinder around the axis PARAMETERS axis 1 Name of the first point defining the axis axis 2 Name of the second point defining the axis point 1 Name of the first point defining the linear value value 1 Value in the first point point 2 Name of the second point defining the linear value value 2 Value in the second point Example of use see Figure 5 10 CYLINDER RADIUS VARYING AP1 AP2 P1 1 3 P2 2 P1 is a point on the inner cylinder the value on the i
265. is Wirefram Connect Direct access Shortcut Command buttons commands menu last given input gt T e Band Line mode input Cursor position feedback prompt for information geometry names at cursor position shown here typed commands and data are echoed appear here Figure3 2 The graphic mode window is composed of six different areas The six different areas of the graphic mode window are used as follows Graphic display area The geometry and FE models are displayed here The display is automatically updated when new geometry is defined See Section 3 12 1 for examples of how to display the model Within several commands there is a need for selecting geometry e g when boundary conditions are defined and when loads are defined Alternatively to giving line mode commands as explained in Section 5 1 you may select geometry graphically There are three ways of doing this Clicking the left mouse button LMB Dragging a rubber band rectangle using the LMB Polygon selection Position the cursor and press the shift key to define the first polygon point While keeping the shift key pressed repeatedly move the cursor and click the LMB to make a pol ygon Release the shift key and click to define the last polygon point A straight line between the first and last polygon points closes the polygon If the LMB is pressed rather than clicked a rub berband line appears as an aid to de
266. isplays until switched off A label switched off will disappear with the next display or RE DISPLAY and remain off until switched on If a label is currently switched off then ON will be the default choice of the command select by hitting return and vice versa The options COLOUR IDENTIFICATION and NODE SYMBOL are however different in that they are not mere on off switches See further explanations for these options Prefem 5 108 PARAMETERS ALL LABELS BEAM ELEMENT BODY NAME BOUNDARY CONDITION S YMBOL COLOUR IDENTIFICATION DAMPER NAMES ELEMENT NORMAL ELEMENT NUMBER ELEMENT THICKNESS GEOMETRY NAMES LINE DIVISIONS LINE NAME MASS ELEMENT NAMES MATERIAL NAMES MESH CORNERS NODE NUMBER NODE SYMBOL POINT NAME SECTION NAMES SPRING NAMES SUPER NODE SYMBOL SESAM 01 JUN 2003 Program version 7 1 Switch for all labels relevant for the current display This option is no longer active Body name switch Boundary condition symbol switch See Figure 5 36 for an ex planation of the various boundary condition symbols Switch for colour identification of either element thickness or material name assigned See a separate description of this com mand Damper name switch Switch for the positive direction of the element local z axis for 2 D elements as well as the local z axis of beam elements Only relevant when the FE mesh is displayed Element number switch Switch for thickness of 2 D element
267. ive meshes illustrate the so called small cut corner and large cut corner Observe how the mesh changes which is the better one depends on the geometry e g how narrow the sector is Prefem SESAM 3 40 01 JUN 2003 Program version 7 1 Figure 3 43 shows alternatives for meshes with a triangular element in a sharp corner Rather than stud ying the logic of the options the figure may be used as follows Decide which mesh you want find which option this corresponds to and use the SET MESH CORNER TYPE command to specify that option Figure 3 44 shows how the SET MESH EDGE RECTANGULAR command is used to solve the particu lar problem of meshing a surface with a notch not necessarily 90 degrees a mesh corner is indicated by this symbol Figure 3 34 Quadrilateral and triangular element mesh for surface with 4 mesh corners Figure 3 35 Quadrilateral element mesh for surface with 3 mesh corners Figure 3 36 Quadrilateral element mesh for surface with 2 mesh corners a bad mesh in this case SESAM Prefem Program version 7 1 01 JUN 2003 3 41 OERE Figure3 37 Quadrilateral element mesh for surface with 1 mesh corner E Figure 3 38 Quadrilateral element mesh for surface with no mesh corners 7 Only 1 element here Figure 3 39 Quadrilateral element mesh for surface with 5 mesh corners a special case CA IN WG ms Prefem SESAM 3 42 01 JUN 2003 Program version 7 1 1 lt Only 1 element here
268. l bodies all elements and all nodes are selected Bodies are to be selected Select bodies See Section 5 1 on how to perform a selection Elements are to be selected Select elements See Section 5 2 on how to perform a selection Lines are to be selected Select lines See Section 5 1 on how to perform a selection Nodes are to be selected Select nodes See Section 5 2 on how to perform a selection Points are to be selected Select points See Section 5 1 on how to perform a selection Spring or damper elements are to be selected Select spring and or damper elements These are selected in a similar way as selecting nodes and elements see Section 5 2 Surfaces are to be selected Select surfaces See Section 5 1 on how to perform a selection DEFINE SET SETA UNION LINE AI1 END END END END DEFINE SET SETB UNION LINE AI amp 1 AJ END END END END DEFINE SET SETC UNION LINE SETA END INTERSECT LINE SETB END END END END At this point SETC will only contain the line AI11 if this line exists SESAM Prefem Program version 7 1 01 JUN 2003 5 83 DEFINE SHAPE PLANE name point point2 point3 SPHERE name centre r CYLINDER name pointl poimt2 r SHAPE CONE name pointl point2 rl 12 linel t line2 k INTERPOLATION name point point2 END END PURPOSE The command defines a shape Shapes are tools in the form of surfaces and are used for
269. lements have 3 d o f s This element type cannot be used as stiffener for shell elements The reason for this is In order to create a surface mesh shell elements the bounding lines must be meshed first If these are meshed with truss elements the number of d o f s will be set to 3 Prefem is unable to increase number of d o f s for existing nodes from 3 to 6 which would be required to add shell elements 3 4 0 Elements for Points Certain elements are defined directly for geometry points These are the spring damper and mass elements see Table 2 2 and Figure 2 3 The modelling of these is somewhat different from the other elements in that the DEFINE command rather than the SET ELEMENT TYPE command is used to define their existence Note that their material must have been defined using the PROPERTY MATERIAL command prior to defining them The elements are created by the MESH ALL or MESH element name commands element name is the name established in the DEFINE command Note Spring axial and to ground damper axial and to ground and mass elements can only be defined between connected to geometry points 3 4 3 1 D Elements for Lines Curves The 1 D elements are the straight 2 node truss and beam elements and the curved 3 node beam element see Table 2 2 and Figure 2 3 Note that for 1 D elements created on curves arcs splines etc only the nodes will lie on the curve see Figure 3 33 straight 2 node element curved 3 node element parab
270. li most sensitive to oddly shaped sec tions are the following The torsional moment of inertia The shear centre location z component of the UNSYMMETRICAL I and L The shear area in the direction of the y axis SHARY of the I and UNSYMMETRICAL I See Appendix B THEORY Section B 1 for details on the formulae used for calculation of the sectional moduli SESAM Program version 7 1 Prefem 01 JUN 2003 5 191 PROPERTY SECTION section name BAR BAR hz bb bt sfy sfz PURPOSE The command defines a bar cross section PARAMETERS hz bb bt sfy sfz bt hz y bb Figure 5 45 Bar section Height Width at bottom Width at top Factors modifying the shear areas calculated by the program The modified shear areas are see the PRINT SECTION command for an explanation of the parame ters SHARY modified SHARY program sfy SHARZ modified SHARZprogram sfz Prefem 5 192 SESAM 01 JUN 2003 Program version 7 1 PROPERTY SECTION section name BOX BOX hz by ty tb sfy sfz PURPOSE The command defines a box cross section PARAMETERS hz by tt ty tb sfy sfz Figure 5 46 Box section Height Width Thickness of top flange Thickness of webs vertical walls Thickness of bottom flange Factors modifying the shear areas calculated by the program The modified shear areas are see the PRINT SECTION com
271. licking Dragging rubber band still works as selection though accepts all available default commands and parameters aborts the current command accepts a single default value i e the one shown in slanted font Select e Draw Geo displays the geometry Note that as opposed to the DISPLAY GEOMETRY com mand and the corresponding Shortcut command this button is available within any command This makes the button very convenient e g if the mesh is displayed and you enter the PROP ERTY LOAD command to define a load whereupon you realise that you need to have the geome try displayed to select where the load should be applied then click the Draw Geo button and proceed Point must be depressed the default condition to allow graphical selection of points Also the Cursor position feedback see below only works for points when the Point button is depressed Line must be depressed the default condition to allow graphical selection of lines curves Also the Cursor position feedback see below only works for lines when the Line button is depressed Surface must be depressed the default condition to allow graphical selection of surfaces Also the Cursor position feedback see below only works for surfaces when the Surface button is depressed Body must be depressed the default condition to allow graphical selection of bodies Also the Cursor position feedback see below only work
272. lies to the specified layer of layered elements layer Layer number see Section 3 10 2 NOTES Only the two node beam element can handle a line load on part of its length Three node beam shell and membrane elements cannot handle line loads on part of their lengths edges This is accounted for as follows The load is automatically distributed to elements within the specified load length If the start or end position of the load is inside an element then the extent of the load is automatically adjusted to match whole ele ments In such cases the load value is scaled to compensate for the adjustment See the notes of the LINE LOAD type of load for additional information on load applied to membrane ele ments SESAM Program version 7 1 01 JUN 2003 Prefem 5 163 PROPERTY LOAD load case PRESCRIBED ACCELERATION PRESCRIBED ACCELERATION select geometry GLOBAL TRANSFORMED trnam ax ay az arx ary arz LOCAL COORDINATE SYSTEM coord name UNTRANSFORMED iax lay 1az trnam iarx iary larz END PURPOSE The command defines prescribed accelerations This type of load is only relevant for a subsequent dynamic analysis in Sestra A typical application may be to give the foundation of a structure an acceleration and do a dynamic analysis Note As opposed to the gravity load this command does not define an acceleration field The geometry subje
273. linearly dependent of several d o f s of several other nodes PARAMETERS dep node Node number of the dependent node dep dof Degree of freedom to be dependent Enter either of the codes X Y Z R X R Y and R Z X translation in X R X rotation about X etc indep node Node number of the independent node indep dof The independent degree of freedom Enter either of the codes X Y Z R X R Y and R Z In addition to these codes there are codes used for forcing the selected d o f to become so called superl Confer with Section 3 5 8 to select the appro priate code beta Linear dependency factor i e the quotient between the displacement of the de pendent d o f and the displacement of the independent d o f SESAM Prefem Program version 7 1 01 JUN 2003 5 139 PROPERTY LINEAR DEPENDENCY LINE LINE DEPENDENCY ALL TRANSLATIONS ONLY DEPENDENT SELECTED 6 NON DEPENDENT LINE LINE DEPENDENCY dep line indep line PURPOSE The command defines linear dependencies between all or selected d o f s of nodes created on a pair of lines The pair of lines must have the same location overlap The command is intended to be used as illustrated in Figure 5 38 A pair of dependent and independent nodes having the same coordinates will be directly linearly coupled A dependent node located in between two independent nodes will be linearly coupled to these two in propor tion to the dista
274. lines surfaces and bodies An identification of the geometry to generate in the form of the initial character s of the program defined geometry names see below for a description of these names Using a single character A B will normally be best allowing the re maining seven characters see Section 2 7 5 to be used for the rest of the geometry names Specification of the topological I J K space i e the number of points to generate in the three topological directions I J and K All geometry names generated reflect their positions in this topological space The names will also reflect the type of ge ometry Specification of type and position of the geometrical coordinate system to use in the geometry generation The options are CARTESIAN CYLINDRICAL start xyz z axis xyz r axis XyZ SPHERICAL start xyz z axis Xyz r axis XyZ The CARTESIAN option involves using the coordinate system of the model for the geometry generation The CYLINDRICAL and SPHERICAL options involve de fining such coordinate systems relative to the coordinate system of the model and then using these systems for the geometry generation Note that the resulting ge ometry will always be in the cartesian coordinate system of the model Specification of the starting point and the vectors for mapping the topological space into the geometrical coordinate system This will consist of starting point I vectors J vectors K vectors The starting point dete
275. load applies to the inside of shell surfaces MIDDLE SURFACE SHELL ELEMENT The load applies to the middle of shell surfaces OUTSIDE SURFACE SHELL ELEMENT The load applies to the outside of shell surfaces BEAM ELEMENTS The load applies to beam elements MEMBRANE ELEMENT The load applies to membrane elements MIDDLE LAYER LAYERED ELEMENT The load applies to the specified layer of layered elements layer Layer number see Section 3 10 2 NOTES The membrane element has by definition no stiffness perpendicular to its surface the element can only carry in plane loads When a line load is applied to membrane elements Prefem will therefore discard any com ponents out of plane as shown in the example of Figure 5 40 Q7 4 7 line load as specified line load as interpreted Figure 5 40 Line load components out of plane for membrane elements are neglected Now consider the example of Figure 5 41 The vertical plus horizontal membrane elements are physically able to carry the line load illustrated in the left most sketch However Prefem will apply such a load to either the horizontal or the vertical membrane which of them cannot easily be foreseen by the user And in either case the horizontal or the vertical component of the load will be discarded as illustrated by the two SESAM Prefem Program version 7 1 01 JUN 2003 5 157 sketches in the middle The user therefore has to decompose the line load and apply each component sepa rately as illus
276. lues to the neutral axis PARAMETERS area ix iy Figure 5 49 General cross section Cross sectional area gt 0 Torsional moment of inertia about shear centre gt 0 Moment of inertia about y axis gt 0 SESAM Program version 7 1 iz iyz wxmin wymin wzmin shary sharz shceny shcenz sy SZ Prefem 01 JUN 2003 5 197 Moment of inertia about z axis gt 0 Product of inertia about y and z axes Minimum torsional sectional modulus about shear centre 2 0 Minimum sectional modulus about y axis 2 0 Minimum sectional modulus about z axis 2 0 Shear area in the direction of the y axis 2 0 Shear area in the direction of the z axis 2 0 Shear centre location from centroid the y component Shear centre location from centroid the z component Static area moment about y axis 2 0 Static area moment about z axis 0 Prefem SESAM 5 198 01 JUN 2003 Program version 7 1 PROPERTY SECTION section name I I hz bt Jtt ty bb tb sty sfz PURPOSE The command defines a symmetrical I or H cross section bt AZ tt hz i ty tb bb Figure 5 50 I section PARAMETERS hz Height bt Width of top flange tt Thickness of top flange ty Thickness of web bb Width of bottom flange tb Thickness of bottom flange sfy sfz Factors modifying the shear areas calculated by the program The modified shear areas are see the PRINT SECTION command for an explanation of t
277. lumn That way is probably quicker and you will at the same time learn about alternatives to the commands you are entering by examining the Command menu The modelling procedure step by step Use the command SET DEFAULT AUTOMATIC NAMING ON to let the program give names to geom etry you define Not having to specify geometry names the modelling will be quicker Note that for more complicated models you may want to control the naming of geometry in order to take advantage of Prefem features based on a systematic naming see Section 3 9 3 Use DEFINE POINT to define the four points shown in Figure 3 7 Having defined the points leave the DEFINE POINT command by typing or by clicking the Direct access button SESAM Prefem Program version 7 1 01 JUN 2003 3 11 ae E Point coordinates 0 0 0 0 40 0 0 40 50 0 0 50 The complete geometry shown EX with dashed lines Figure 3 7 Tutorial the first four points spanning the initial surface View the model along the X axis by clicking the Direct access button View X axis in the leftmost col umn Give the command DEFINE SURFACE and click the four points to define a surface Start at any of the four points proceed in a rotational sequence and close the surface by a fifth click at the starting point Generally leave commands by typing or by clicking the Direct access button Complete datasets will be saved Note however that certain comma
278. m e g Sestra depending on the type of element The direction of the z axis may however be reversed by the CHANGE ROTATION OF SURFACE and CHANGE NORMAL OF SURFACE commands Also see Section 3 12 3 The layered element type however require the local coordinate system to be defined i e the orientation of the local x and y axes This is done by the PROPERTY LOCAL COORDINATE SURFACE command Note that this command will have no effect for other than layered elements 3 5 6 Material The PROPERTY MATERIAL command is used for defining the material types Elastic for all element types except for sandwich elements Prefem SESAM 3 50 01 JUN 2003 Program version 7 1 Anisotropic for 2 D and 3 D elements for which orthotropic or anisotropic material is desired also for sandwich elements option 3D SHELL ELEMENT for giving different anisotropic material for the layers Spring for axial and to ground spring elements note that the spring material must be defined prior to defining the spring elements see the DEFINE SPRING command this is in contrast with what is the case for other elements and their material e Damper for axial and to ground damper elements note that the damper material must be defined prior to defining the damper elements see the DEFINE DAMPER command this is in contrast with what is the case for other elements and their material e Mass for one node mass elements note that the one node mas
279. m layers of the plates with their eccentricities Stiffener layers are drawn as simple lines through the neutral axes between cross sections The stiffener cross sections are drawn both with outline of the sections as defined and scaled to represent the area corresponding to the element size This representation of area is illustrated in Figure 5 55 If the element size exactly matches a whole number of stiffener spac ings for example 2 as in the sketch to the left the sum of the stiffener areas corresponds exactly to the effective stiffener ar ea If the element size is for example between 2 and 3 stiffener spacings as in the sketch to the right then the areas ofthe 2 stiff eners drawn are scaled so as to represent the effective stiffener area Note that the number of stiffeners drawn will be the element size divided by the stiffener spacing and truncated to a whole number At least one stiffener will however always be drawn The stiffeners are centrally positioned on the element Plate layers are drawn as simple shells with their eccentrici ties Stiffener layers are drawn as simple lines through the neutral axes between outlines of the cross sections as Layered elements are drawn as simple shells only eccentrici ties are ignored Plate and stiffener layers are not explicitly drawn The plate and stiffener layers are drawn as for the OUTLINE AREA option see this and in addition the stiffeners are drawn as extrusion
280. m overview an overview of all major SESAM programs and how they communicate is shown in Figure 1 2 The program Manager manages an analysis job including modelling analysis and results processing by acti vating the proper programs and handling the files involved SESAM Program version 7 1 Prefem 1 4 01 JUN 2003 DINISSHIOUdLSOd SISNIVNY TY LNGAINNOULANG DNISSWOO IgdH Id S ISVIVNV PLE RS Rs CRAT DINN SH VM Vd INVHDO IAd LUCR Re FCRI Figure 1 2 SESAM overview SESAM Prefem Program version 7 1 01 JUN 2003 1 5 1 3 How to read the Manual If you are a new user you may proceed as follows Read Section 2 1 Modelling Principles to learn about some basic concepts of Prefem Read Section 2 2 Geometry Modelling and Section 2 3 FE Model Creation for introductions to model ling Go then to Section 3 1 Getting Started the Graphical User Interface to learn how to operate Prefem and to Section 3 2 Tutorial in Midship Section Modelling were you will be guided through a small but complete modelling session After completing the tutorial you may achieve a more complete understanding of geometry modelling FE model creation defining and assigning properties as well as defining loads from Section 3 3 through Section 3 6 Having done the above steps you should have an adequate understanding of Prefem enabling you to pro ceed with practical modelling work while referring to the other sections of
281. mand for an explanation of the parame ters SHARY modified SHARY program SFY SHARZ d SHARZ sfz modifie program SESAM Prefem Program version 7 1 01 JUN 2003 5 193 PROPERTY SECTION section name CHANNEL POSITIVE CHANNEL hz by tz ty sfy sfz NEGATIVE PURPOSE The command defines a channel cross section Z Z tz hz y y ty tz D e Negative Positive Figure 5 47 Channel section PARAMETERS hz Height by Width of top and bottom flanges tz Thickness of top and bottom flanges ty Thickness of web sfy sfz Factors modifying the shear areas calculated by the program The modified shear areas are see the PRINT SECTION com mand for an explanation of the parameters SHARY modified SHARY program sfy SHARZ modified SHARZ program Sfz POSITIVE NEGATIVE Web location in the local y direction Prefem 5 194 SESAM 01 JUN 2003 Program version 7 1 PROPERTY SECTION section name DOUBLE BOTTOM DOUBLE BOTTOM hz ty tb tt by sfy sfz PURPOSE The command defines a double bottom type cross section PARAMETERS hz ty tb tt by sfy sfz Figure 5 48 Double bottom section Height Thickness of web Thickness of bottom flange plate Thickness of top flange plate Effective width of plates Factors modifying the shear areas calculated by the program The modified shear areas are see the PRINT S
282. mand or by typing a line mode command you may rotate and zoom to get a better view The buttons and are logged with the default values they accept The button is logged as is The other buttons are not logged see Section 4 1 5 on logging commands The Direct access but tons are sorted in three groups as follows View e Pan allows panning shifting the display Click the button then press and hold the LMB within the Graphic display area and a bounding box of the model appears Move the mouse and release the LMB and the model will be displayed in its new position Note that the coordinate axes drawn together with the bounding box do not show the position of the origin of the model Rotate allows interactive rotation of the display Click the button then press and hold the LMB within the Graphic display area and a bounding box of the model appears Move the mouse up and down to rotate the model about a screen horizontal axis and move left and right to rotate about a screen vertical axis A circular motion will rotate the model about an axis normal to the screen in the opposite direction of the circular motion When the LMB is released the model is displayed in its new position Note that the coordinate axes drawn together with the bounding box do not show the position of the origin of the model X axis Y axis and Z axis display the model as seen along the model s X Y and Z axis respectively
283. me of a previously defined coordinate system This may have been defined by the DEFINE COORDINATE SYSTEM command or a previous GENERATE command The cartesian coordinate system of the model is used A cylindrical coordinate system is defined and used The coordinate system de fined is given a name as explained in Section 3 3 7 A spherical coordinate system is defined and used The coordinate system defined is given a name as explained in Section 3 3 7 Cartesian coordinates of the origin of the coordinate system Cartesian coordinates of a point defining the z axis for cylindrical coordinate sys tem or pole axis for spherical coordinate system Cartesian coordinates of a point defining the 0 plane which determines the r axis The cartesian coordinates of the starting point For cylindrical coordinates r0 0 Z0 are given For spherical coordinates r0 0 00 are given This optional command allows repeating the subsequently given vector a specified number of times The number of times to repeat the subsequently given vector The cartesian components of the I vectors For cylindrical coordinates drI dol dzI are given For spherical coordinates drl dol dOI are given The number of vectors to give corresponds to the topology range Conclude enter ing vectors by END If less vectors than required by the topology range are given then the last vector is repeated the required number of times If too many vectors are give
284. med by enclosing them in parentheses let f and g be the two functions g Note that without the left parenthesis the program will recognise f as a complete expression and not allow continuation of the expression Figure 5 5 Example of exponential function Prefem SESAM 5 10 01 JUN 2003 Program version 7 1 LINEAR 2POINTS VARYING LINEAR 2POINTS VARYING point 1 value 1 point 2 value 2 PURPOSE The command defines a linearly varying value interpolated on the line between two points The value at any point on the line between the two points and the extension of this line will apply to all points in a plane perpendicular to the line and through the point in question Also see Figure 3 55 for an illustration of this PARAMETERS point 1 Name of the first interpolation point value 1 Value for the first interpolation point point 2 Name of the second interpolation point value 2 Value for the second interpolation point Example of use see Figure 5 6 LINEAR 2POINTS VARYING P1 2 5 P2 1 Surface subjected to load Point node where value is sought l P2 2 5 Projection line normal to line P1 P2 90 angle Pl Figure 5 6 Example of use of LINEAR 2POINT VARYING function SESAM Prefem Program version 7 1 01 JUN 2003 5 11 LINEAR 3POINTS VARYING LINEAR 3POINTS VARYING point 1 value 1 point 2 value 2 point 3 value 3
285. ment D a olal 5 o 2g amp 858l 9 4 5l cH cee ee S ios o 2 S S gt e g 2 ME z e e 3 o gt M o o ue 88 8 B EISE a e S 5 uul amp as o29 2 Triangular prism X X x x x X 4 Linear hexahedron X X X X X x ee A Isoparametric triangular prism X X X X X X Isoparametric hexahedron x X x x x x 2 Spring to ground E dde d xial spring a E Damper to ground eb Axial damper amp General one node mass element x Notes in the table above 1 Only the in membrane plane component of a line load is taken into account in Sestra see further expla nation for the PROPERTY LOAD load case LINE LOAD command 2 The extent of the load is adjusted to match whole elements and the magnitude is scaled to compensate for this adjustment 3 In spite of note 1 above gravity out of membrane plane is allowed 4 Only as axi symmetric load 2 7 5 Constraints on Names Names given by the user cannot start with the letter X this is reserved for program generated names Length of names is limited to 8 characters 2 8 Mass Modelling The Sestra analysis program will automatically generate element mass based on the volume of the elements and density of the material Additional mass may be modelled in Prefem as follows Prefem SESAM 2 12 01 JUN 2003 Program version 7 1 The PROPERTY POINT MASS command enables definition of point masses diagonal mass matrices for selected geometry po
286. mentation purposes and is not required to establish a complete model The descriptions are reproduced in tables produced by the PRINT command The description of sets are also stored on the Input Interface File and transferred together with the sets to the Results Interface File PARAMETERS name Name of a previously defined section material or set text The description consisting of maximum four character strings each of maximum 64 characters and enclosed in single quotes If less than four strings are to be en tered conclude by entering END EXAMPLES A description for the previously defined set MYSET is given by CREATE DESCRIPTION MYSET This set includes all 2 node beam elements No shell elements are included END SESAM Prefem Program version 7 1 01 JUN 2003 5 53 CREATE MESH name of geometry ADJUST select surfaces ALL MESH CRACK select geometry PART Pt ALL SPRINGS DAMPERS INCLUDED a This option is presently inactive PURPOSE The command creates the FE mesh plus damper and spring elements The command is equivalent to the MESH command Prefem SESAM 5 54 01 JUN 2003 Program version 7 1 CUT tool GENERAL PLANE point point2 point3 select surfaces drag mouse GRAPHICS END CUT XY PLANE dz XZ PLANE dy select lines PREDEFINED PLANE REPEAT YZ PLANE dx END Where pointl
287. ments are to be connected See Section 5 1 on how to perform a selection Name of a previously defined material of type damper AXIAL or TO GROUND whichever is relevant GLOBAL The material constants of the damper refer to the cartesian coordinate system of the model TRANSFORMED The material constants of the damper refer to a transformed coordinate system trnam Name of the transformation used SESAM Prefem Program version 7 1 01 JUN 2003 5 63 DEFINE INTERSECTION INTERSECTION name start point end point guiding point shapel shape2 nelm PURPOSE The command defines the geometric entity intersection curve The curve is determined as the intersection between two previously defined shapes see the DEFINE SHAPE command Note that the intersection curve must go from one point to another defining a boundless intersection curve between two shapes is therefore not possible The intersection between e g a plane and a cylinder will give two curves one being the short way between the two points and another the long way around the cylinder A guiding point in the vicinity of the middle of the desired intersection curve is used to select the proper one A guiding point must be given even in cases where there is only one intersection curve intersection between two planes PARAMETERS name User given name of the intersection curve start point Name of the point defining the start point
288. mmand specifies the name of the command input file The file extension of the command input file must be JNL The command will read commands stored on the command input file into the program The commands read will have the same effect as if they were entered from the keyboard Several command input files may be used in sequence but only one command input file can be used at a time The command input file name cannot be the same as the command log journal file name See Section 4 1 5 for information on the command input file You may however find it more convenient to specify a command input file when starting Prefem from Manager PARAMETERS file prefix File name prefix file name File name excluding the mandatory file extension JNL Prefem 5 216 01 JUN 2003 SET DEFAULT ADJUST MESH ON AUTOMATIC NAMING COPY ELEMENT TY PE ie LINE element type ELEMENT TYPE SURFACE RONE BODY EYE DIRECTION eyex eyey eyez FORCE TO SUPER pErAupr NPARPEPENDENCY MODE NO FORCE TO SUPER NONE LOCAL COORDINATE BEAM YX PLANE ZX PLANE MATERIAL material name MAX ELEMENT LENGTH length NUMBEROF ELEMENTS nelm SECTION section name THICKNESS thickness PURPOSE The command sets various default conditions PARAMETERS ADJUST MESH AUTOMATIC NAMING SESAM Program version 7 1 Switch on off automatic mesh adjustment in connection with changing the
289. mrx pmry pmrz PURPOSE The command defines point masses in nodes The point masses may only be applied in geometry points A point mass is in effect a diagonal mass matrix whereas the mass element see the PROPERTY MATE RIAL material name MASS command allows definition of off diagonal terms The contribution to the mass matrix are allowed to differ between the degrees of freedom However giving the same mass for the three translational degrees of freedom will normally be the only physically meaning ful choice The rotational mass for the three rotational degrees of freedom may often be set to zero as their influence on the analysis results will normally be insignificant PARAMETERS select points Select points See Section 5 1 on how to perform a selection pmtx Translational mass in the X direction pmty Translational mass in the Y direction pmtz Translational mass in the Z direction pmrx Rotational mass about the X axis pmry Rotational mass about the Y axis pmrz Rotational mass about the Z axis NOTES Point masses are accumulated if repeatedly given for the same point SESAM Program version 7 1 PROPERTY SECTION Prefem SECTION section name 01 JUN 2003 5 189 BAR BOX CHANNEL DOUBLE BOTTOM GENERAL I L PIPE UNSYMMETRICAL I PURPOSE The command defines cross sections for beam and truss elements The program offers dif
290. n 5 3 PARAMETERS See the explanation for the line load SESAM Program version 7 1 Prefem 01 JUN 2003 5 159 PROPERTY LOAD load case NORMAL PRESSURE NORMAL PRESSURE select surfaces p INSIDE SURFACE ip MIDDLE SURFACE OUTSIDE SURFACE INSIDE LAYER END MIDDLE LAYER layer OUTSIDE LAYER PURPOSE The command defines normal pressure loads e g hydrostatic and air pressures on surfaces For shell elements the pressure is applied to the inside middle or outside surface of the elements For the concept of inside and outside of surfaces see Section 3 12 3 The inside middle and outside layer is similar but is relevant for layered elements For solid elements the inside middle and outside surface specification is irrelevant and not used As opposed to the component pressure for which the direction of the pressure is solely determined by the sign of the pressure components the direction of the normal pressure is determined by its sign combined with the inside outside definition See Section 3 12 3 for an explanation of this Alternatively to giving a constant normal pressure a varying pressure may be specified by functions see Section 5 3 PARAMETERS select surfaces p ip INSIDE SURFACE MIDDLE SURFACE OUTSIDE SURFACE INSIDE LAYER MIDDLE LAYER OUTSIDE LAYER layer Select surfaces See Section 5 1 on how to perform a selection Normal pressure A positive pressure
291. n A amp 1 amp amp 2 has been defined based on point BP1342 then the name of a copy of point AP1342 if existing will be in conflict with the existing point BP1342 Prefem will in such cases select another name for the copy of AP1342 The copying will succeed at the cost of a system in geometry naming Here are two examples of wild card used in defining lines DEFINE LINE AL amp 11 AP amp 11 AP amp 12 DEFINE LINE AL amp 11 AP amp 11 AP amp 1 SESAM Prefem Program version 7 1 01 JUN 2003 3 63 These commands define new lines whenever a pair of existing points matches the pair of point specifica tions given The matching pair of points must have the same character in the position of the amp This charac ter is used in constructing the name of the created line i e amp replaces the same character in all three names The and signs may also be used implying an incrementation or decrementation of the previous point name The and symbols are only allowable in the DEFINE LINE command The commands above are functionally identical 3 9 4 Defining and using Sets for Selection of Geometry Named sets consisting of parts of the geometry model bodies surfaces etc are defined by the DEFINE SET command Such sets may be referred to when assigning properties and loads and in the DISPLAY and PRINT commands Within the DEFINE SET command operations are performed to specify the contents of the set The following operations are available
292. n may give 1 0 or 1 as result depending on the numerical accuracy MAX MIN determines the maximum minimum of the two arguments For example MAX al a2 al ifal gt a2 MIN al a2 a2 for the same condition DIM calculates the positive difference between the two arguments as follows e DIMala2 al a2ifal a2 e DIM al a2 20 ifal a2 SQRT calculates the square root of the argument A square root function is established by using the LIN EAR 2POINTS VARYING function as argument See the explanation for the SIN COSIN functions for how to use the SQRT function The square root function is equivalent to giving the function argument 0 5 PARAMETERS argument Argument or function argument Argument or function argument2 Argument or function SESAM Program version 7 1 Prefem 01 JUN 2003 5 21 5 4 Detailed Description of Commands The input commands are described in the following The commands and subcommands are described in alphabetic order Below is a list of all main basic level commands ADD DISPLAY CHANGE See page 5 25 CHECK See page 5 40 CONNECT See page 5 47 COPY See page 5 48 CREATE See page 5 51 CUT See page 5 54 DEFINE See page 5 56 DELETE See page 5 92 DISPLAY See page 5 96 EXIT See page 5 98 EXTRUDE See page 5 99 GENERATE See page 5 102 HELP See page 5 105 JOIN See page 5 106 LABEL See page 5 107 LOCATE See page 5 112 MESH See page 5 113 PLOT See page 5 115 PRI
293. n no load will apply If e g both beam and shell elements are present then the load may be applied to either of them The choice between beam and shell elements has consequences though see under NOTES below Concerning part line load on membrane elements see the warning under NOTES of the command PROP ERTY LOAD load case LINE LOAD For shell elements the load is applied to the inside middle or outside surface of the elements For the con cept of inside and outside of surfaces see Section 3 12 3 For layered elements the load is applied to the middle layer of an identified layer number PARAMETERS line Select a single line GLOBAL The load components refer to the model s cartesian coordinate system SESAM Program version 7 1 TRANSFORMED LOCAL COORDINATE SYSTEM UNTRANSFORMED trnam coord name fx fy fz DEG PHASE ANGLE IMAGINARY COMPLEX RAD PHASE ANGLE END phx phy phz ifx ify ifz pointl distl point2 dist2 INSIDE SURFACE SHELL ELEMENT MIDDLE SURFACE SHELL ELEMENT OUTSIDE SURFACE SHELL ELEMENT BEAM ELEMENTS Prefem 01 JUN 2003 5 161 The load components refer to a previously defined transforma tion of the cartesian coordinate system see the command DE FINE TRANSFORMATION The load components refer to a previously defined cylindrical or spherical coordinate system see the command DEFINE COORDINATE SYSTEM No additional transformation of the cylindrical or spherical coordinate sy
294. n the superfluous vectors are discarded The cartesian components of the J vectors For cylindrical coordinates drJ doJ dzJ are given For spherical coordinates drJ doJ d0J are given The cartesian components of the K vectors For cylindrical coordinates drK doK dzK are given For spherical coordinates drK d K d K are given Coordinate systems implicitly defined by the GENERATE command using the options CYLINDRICAL and SPHERICAL have the same application area as coordinate systems explicitly defined by the DEFINE COORDINATE SYSTEM command SESAM Prefem Program version 7 1 01 JUN 2003 5 105 HELP SUPPORT GENERAL SYNTAX SPECIAL KEYS STATUS LIST HELP PURPOSE The command provides information on subjects PARAMETERS SUPPORT The telephone and telefax numbers and the Internet address for requesting support is printed together with detailed information on the program version used This in formation is of interest in connection with support requests The information is printed in the print window line mode window on Unix GENERAL SYNTAX Information on how to enter commands and text is provided The information is printed in the print window line mode window on Unix SPECIAL KEYS Information on some special keys is provided The information is printed in the print window line mode window on Unix STATUS LIST If the program is used in line mode Unix only the Status List is printed on the
295. nce temperature That is the values to give are the temperature changes compared to an initial and strain less state The thermal expansion coefficient is defined by the PROPERTY MATERIAL command The temperature difference is assigned to all elements within the selected geometry Repetitive use of this command does not involve accumulation of temperatures like other load types new values will replace pre vious values Care must be taken when assigning temperature differences to avoid giving the same node of an element different values as there is no way of determining which value will be used If two or more dif ferent values are assigned to a node given in two different load commands any of the given values may be assigned to the element The three methods of assigning temperature loads have one significant difference ONE VALUE EACH NODE and TWO VALUES ON SHELL assign the temperature only to the elements of the selected geome try itself whereas VALUE ON NEIGHBOURING ELEMENTS also assigns the temperature to elements adjoining the selected geometry For example using the VALUE ON NEIGHBOURING ELEMENTS option to give a temperature for a selected surface will also assign the temperature to the nodes in the selected surface of adjoining solid elements However elements on the borderlines of the surface will not be assigned the temperature and neither will elements of neighbouring surfaces Another example Using the VALUE ON NEIGHBOURING ELEME
296. nces The dashed arrows indicate the linear dependency relations indep line gt lt _6 _ 6 RS oo ger i U 774a na a e U dep line 35 A A ae The dep line and indep line must have the same location they are here drawn apart only for illustration purposes Figure 5 38 Line line dependency PARAMETERS dep line Select lines to be dependent See Section 5 1 on how to perform a selection indep line Select the independent lines See Section 5 1 on how to perform a selection ALL All d o f s of the dependent nodes are linearly dependent of the corresponding d o f s of the independent nodes TRANSLATIONS ONLY Only the translational d o f s of the dependent nodes are linear ly dependent of the corresponding d o f s of the independent nodes SELECTED The d o s to be dependent are to be selected individually Prefem SESAM 5 140 01 JUN 2003 Program version 7 1 DEPENDENT The d o f in question of the dependent nodes is dependent of the corresponding d o f of the independent nodes NON DEPENDENT The d o f in question of the dependent nodes is not dependent of the corresponding d o f of the independent nodes nor of any other d o f NOTES The dependent lines should be the ones with the largest number of nodes SESAM Program version 7 1 Prefem 01 JUN 2003 5 141 PROPERTY LINEAR DEPENDENCY RIGID BODY DEPENDENCY RIGID BODY DEPENDENCY select geometry point
297. nd Gij G j are the shear strain shear stress and shear modulus respectively in the plane defined by axes nos 1 and j Hence the terms of the elasticity matrix becomes dll E 1 v15v51 d21 v9 Ey 1 V15v2 V12 E2 1 V12V21 d22 E 1 v15V51 d31 d32 0 d33 G1 d41 d42 d43 0 d44 G3 d51 d52 d53 d54 0 d55 G31 The material constants Young s modulus and Poisson s ratio v in the three directions are related as fol lows V21 1 V12 E V31 E17 V13 3 V32 E2 V23 3 where the second and third relations are irrelevant for the 3D shell orthotropic material Prefem 5 182 SESAM 01 JUN 2003 Program version 7 1 PROPERTY MATERIAL material name ANISOTROPIC SOLID ELE MENT SOLID ELEMENT GLOBAL TRANSFORMED trnam rho dll d21 d22 d31 d32 d33 d41 d42 d43 d44 d51 d52 d53 d54 d55 d61 d62 d63 d64 d65 d66 dampl damp2 damp3 alphal alpha2 alpha3 PURPOSE The command specifies the data for either an anisotropic or orthotropic material for solid elements The anisotropic material has three material axes which in general will not constitute an orthogonal system if so it will be an orthotropic material PARAMETERS GLOBAL TRANSFORMED trnam rho dll d66 dampl damp2 damp3 alphal alpha2 alpha3 lan d21 d22 d
298. nds are not complete until one or two END commands have been entered The PROPERTY LOAD command is an example of such a command Use CUT ALL SURFACES INCLUDED PREDEFINED PLANE to cut first horizontally and thereafter vertically The first cut is parallel with the XY PLANE and at Z coordinate 18 metres The second cut is parallel with the XZ PLANE and at Y coordinate 15 metres Refresh the display after the CUT commands by clicking either the Shortcut command Display Geom etry or the Direct access button Select Draw Geo The difference between the two is that the latter may be clicked within any command e g at the point where you want to select geometry by clicking Note that after commands that change the current geometry CUT DEFINE ROUNDED CORNER DEFINE SECTOR CORNER CHANGE POINT you should refresh the display before graphically selecting geometry Refreshing the display is also relevant in order to remove highlighting of geometry caused by graphical selection Use DEFINE ROUNDED CORNER to round off the corner of the surface located in the origin this will be the bilge First click the two lines at both side of the corner thereafter give the radius 10 metres and conclude by requesting the corner the area outside the arc to be deleted in the rounding off operation Use CHANGE POINT to move the upper left point 0 0 50 down 2 metres this will form the sloping outer deck After clicking the point use the less than
299. ner point of the surface is referred to together with a point on the inside outside of the surface PARAMETERS INSIDE OUTSIDE select surfaces corner point POINT point name COORDINATES XYZ XYZ X Y Z NOTES The inside of the surface will be defined The outside of the surface will be defined Select surfaces See Section 5 1 on how to perform a selection A corner point of the surface This is not requested when more than one surface is selected An existing point is used for defining the inside outside of the surface s Name of a point A point in space defined by coordinates is used for defining the inside outside of the surface s Cartesian coordinates A point in infinity along the positive negative X Y or Z axes is used for defining the inside outside of the surface s When selecting several surfaces the inside outside definition must apply to all points of all selected surfaces otherwise ambiguities may arise SESAM Prefem Program version 7 1 01 JUN 2003 5 237 The last inside outside definition for a surface is the valid one for all loads irrespective of whether the loads were defined before or after the inside outside definition In other words a surface can only have one inside outside setting Prefem The command switches on and off logging in command log file see Chapter 4 of print or graphics com GRAPHICS Switch for graphics commands like DISPLAY SET GRAPHICS
300. ners have section types materials eccentric ities directions and spacing The plates have thicknesses materials and eccentricities The command for creating stiffened plates also covers other plate type structures like e g corrugated plates reinforced con crete and lay ups of laminates The command for defining the layered element refers to materials and sections These must previously have been created The section must be of the BAR trapezoid type One layer is defined at a time The layers are either PLATE layers or STIFFENER layers There is no restriction on the order or number of PLATE and STIFFENER layers The number of layers constituting the layered element is a result of the number of times a plate stiffener layer is defined The stiffened plates require a local coordinate system This may for convenience be selected so that the main stiffener has an angle of 0 with the local x direction of the plate elements The local coordinate sys tem for the plate elements is defined by the PROPERTY LOCAL COORDINATE SURFACE command The defined layered elements are assigned to surfaces by the CONNECT command The relevant surfaces also have to be assigned layered element type by the SET ELEMENT TYPE SURFACE command A layered element may be verified graphically See the SET GRAPHICS PRESENTATION LAYERED ELEMENT command which offers several options for displaying the plate thickness and stiffener section Bear in mind however that the st
301. ng of the model is facilitated by the fact that properties are assigned to the geometry instead of to the FE model SESAM Prefem Program version 7 1 01 JUN 2003 2 3 Modelling with Prefem will typically consist of the following steps 1 Defining the geometry model 2 Defining data determining the FE mesh element density and types etc and requesting automatic crea tion of the FE mesh e g by the command MESH ALL 3 Defining properties material data boundary conditions loads etc 4 Verifying the model by printing and displaying data 5 Storing the completed FE model on the Input Interface File see Section 2 13 for transfer to analysis programs Step 3 defining properties may as well be performed prior to or in combination with step 2 In addition to creating FE models for structural analysis Prefem is used for creating hydrodynamic analysis models so called panel models analysed by Wadam The steps of modelling a panel model are the same as for modelling a FE model When exiting the program during modelling Prefem will automatically save the model thereby allowing the modelling work to be resumed at a later stage 2 2 Geometry Modelling The geometrical entities are described in Table 2 1 The complete geometry model may consist of any number and any combination of these entities Table 2 1 Geometrical entities Entity Definition Point Coordinates x y z Line Straight line between t
302. nner cylinder is 1 3 P2 is a point on the outer cylinder the value on the outer cylinder is 2 The function for any line normal to and starting at the axis will be the same AP 1 and AP2 define the axis Figure 5 10 Example of use of CYLINDER RADIUS VARYING function SESAM Prefem Program version 7 1 01 JUN 2003 5 15 VALUE BETWEEN VALUE BETWEEN point 1 point 2 value PURPOSE The command limits the application of a value or function to a specified space Outside the space the value will be zero The application is limited to the space in between the two parallel planes normal to the line between the two points and through the points Note Be aware of the difference between this function and ONLY BETWEEN by studying the examples given for each Note When used to describe a line load for a two node beam element the interpretation of this func tion is somewhat different The reason for this is that a two node beam element contrary to a membrane shell volume element can have a discontinuity of the load Such discontinuity is described by the VALUE BETWEEN function Compare Figure 5 11 and Figure 5 12 to see the difference PARAMETERS point 1 Name of the first limiting point point 2 Name of the second limiting point value Value or function Example of use see Figure 5 11 for membrane shell solid elements and Figure 5 12 for 2 node beam ele ment VALUE BETWEEN P1 P2 1 2
303. node The command is designed to be used in graphic mode but is still logged for re use in line mode through a command input file Move a node as follows e e Select the surface where nodes shall be moved Several identical surfaces identical geometry and identi cal mesh may be selected provided that they are displayed on top of each other seen from an angle so that they overlap In graphic mode give DISPLAY optionally followed by the Direct access button Zoom Fr to display the mesh of the selected surface The view angle should preferably be normal to the mesh rotate the dis play if necessary Position the cursor over the node you want to move and press and hold the left mouse button LMB Drag to the new position of the node and release the LMB The node will be moved the distance the mouse is moved The display will be refreshed with the new node position and another node may be moved The following rules apply to moving nodes e If the node is in a point it will not be moved If the node is on a line it will be moved but only along the line If the node is on a surface projected onto a shape it will be moved and then projected back onto the shape If the node is on a surface not projected onto a shape then three nodes from an element to which the node belongs will be used to form a plane The node will be projected back onto this plane Note This command may give incorrect results for nodes belonging
304. nodes Change properties previously defined Define eccentricities offsets for beams Define hinges for beams Define initial displacements for a dynamic analysis Define initial velocities for a dynamic analysis Define linear dependencies between nodes multi point con straints SESAM Prefem Programversion7 1 01JUNJU08 843 LOAD Define loading conditions LOCAL COORDINATE BEAM Define local coordinate systems for beam elements LOCAL COORDINATE SURFACE Define local coordinate systems for layered elements MATERIAL Define material properties POINT MASS Define point masses in nodes SECTION Define cross sections THICKNESS Define shell and membrane element thicknesses TRANSFORMATION Define transformations Prefem SESAM 5 128 01 JUN 2003 Program version 7 1 PROPERTY BOUNDARY CONDITION select geometry BOUNDARY CONDITION select nodes FIX FREE PRESCRIBED ACCELERATION 6 PRESCRIBED DISPLACEMENT SUPERNODE GLOBAL TRANSFORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam PURPOSE The command defines boundary conditions of the nodes in a selected part of the geometry or for selected nodes directly Boundary conditions are always specified for 6 degrees of freedom d o f s If a node has less than 6 d o f s solid and membrane elements have only 3 d o f s the superfluous boundary condition specifications are ignored
305. normal pressure on ship side bottom Figure 3 5 Tutorial FE mesh plate thicknesses and two load cases Prefem 3 10 01 JUN 2003 SESAM Program version 7 1 E PREFEM 70 04 Thickness 2 0E 02 35 0E 02 Present Col Thi Add display Change Col Mat Check Wirefram Connect Hidden Copy Shrunken Creote oom Fr Refresh Misc Learn Display Geometry Surface Element Mesh Add Mesh Add Load Cut Define Display Extrude Generate Help Join Label Label Boundary Locote Mesh Inv Lines Surfaces Geometry Plot Print Property Re compute Nodes Re display Elements Supernod Mesh Read Rotote 0 Set All Off Write Default Mesh adj Zoom Delete Exit Figure 3 6 The graphic mode window with the midship section model and load case 1 In the following the modelling procedure is described step by step while referring to line mode commands Some times the required command is give in full but generally only the first part is given assuming that the remaining part is self explanatory You may also refer to Chapter 5 where all commands are described in detail Rather than entering the line mode commands through the keyboard you are in this tutorial advised to click the commands in the Command menu the right most co
306. not be selected Prefix for the names of the extruded geometry This prefix precedes default names Copy extrude in the global cartesian coordinate system Copy extrude in a cylindrical coordinate system which is subsequently defined Cartesian coordinates of the origin of the cylindrical coordinate system Cartesian coordinates of a point defining the z axis of the cylindrical coordinate system Cartesian coordinates of a point defining the r axis of the cylindrical coordinate system The point need not be on the r axis rather it must be positioned in the 70 plane The number of copies extrusions to make Optionally specify repetition of the subsequently given vector The number of times to repeat the vector The vector in the global cartesian coordinate system The vector in circumferential direction in the specified cylindrical coordinate system i e the spacing in direction Only copy geometry Copy geometry and extrude points to lines Copy geometry and extrude points to lines and lines to surfaces SESAM Prefem Program version 7 1 01 JUN 2003 5 101 SURFACE TO BODY Copy geometry and extrude points to lines lines to surfaces and surfaces to bodies NOTES The geometry names created by the copying and extrusion are as follows e Points are named prefixPnm where prefix is the relevant one of the copy prefix and extrude prefix nis a sequence number referring to the copying extrusion 1 for the f
307. nsiderations Element local z axis For 2 D surface elements the direction of the local z axis of the elements is decided in Prefem while the local x and y axes are determined by the analysis program e g Sestra The exact direction of the local z axis is also determined by the analysis program as the exact element shape is only known by the analysis program The local z axis is governed by the rotational order of the lines curves defining the surface com bined with the right hand rule see Figure 3 67 Note Coplanar neighbour surfaces defined with opposite rotational order will give neighbour shell elements with opposite local z axes Principally there is nothing wrong in this but the interpre tation of the results will be confusing and prone to error as corresponding stress components belong to opposite shell surfaces SESAM Prefem Program version 7 1 01 JUN 2003 3 75 The rotational order of a surface and thereby the local z axis of its elements is changed by the CHANGE ROTATION OF SURFACE command Alternatively the CHANGE NORMAL OF SURFACE command may be used DEFINE SURFACE S L1 L2 L3 L4 DEFINE SURFACE S L1 L4 L3 L2 L2 general direction of elements local z axes L2 L4 default general direction of outsides elements local z axes Figure 3 67 Elements local z axis is determined by surface definition Inside Outside of Surfaces Loads are applied to the inside
308. nslational components of the mass matrix The rotational components and off diago nal terms of the mass matrix are not changed any previously defined rotational mass components are main tained However this change of load to mass is only made on the condition that the forces to be changed and the acceleration of gravity referred to are parallel and with the same sign the X Y and Z components are con sidered in combination and not individually A load including moments is not changed even if its transla tional part the force is parallel with the acceleration of gravity Furthermore a complex load a load including an imaginary part will not be changed this may first be changed to a real load by removing the imaginary part and thereafter be changed to mass The presence of other types of load in the same load case does not prevent the LINE LOAD PART LINE LOAD and BEAM CONCENTRATED LOAD to be changed to mass as long as they meet the requirements above Loads changed to masses are not removed rather they are marked as LOAD TO BE CONVERTED TO MASS this will be seen when printing the loads Therefore if the mesh is deleted and re created the loads are converted to masses for the new mesh PARAMETERS load case The load case to be converted to mass load type The load type of load case to be converted to mass Relevant alternatives are ALL LOAD TYPES CONCENTRATED LINE LOAD PART LINE LOAD and BEAM CONCENTRATED LOAD SESAM
309. ntrated point load force and moment Define gravity load Identify surfaces to be subjected to hydrostatic and hydrody namic pressures computed by a subsequent Wadam analysis Define line distributed load Define line distributed moment Define normal surface pressure Define constant line distributed load on part of a line Define prescribed acceleration Define prescribed displacement Define rigid body acceleration Define rigid body velocity e g rotation Define temperature differences initial strains This option has no relevance It appears as a consequence of the CHANGE PROPERTY LOAD load case TO MASS com mand Prefem 5 146 01 JUN 2003 PROPERTY LOAD load case BEAM CONCENTRATED BEAM CONCENTRATED line GLOBAL TRANSFORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam DEG PHASE ANGLE phx phy phz IMAGINARY COMPLEX ifx ify ifz fx fy fz point distance RAD PHASE ANGLE phx phy phz END PURPOSE SESAM Program version 7 1 The command defines concentrated loads forces acting on two node beam elements This load differs from the CONCENTRATED alternative in that it may be applied anywhere along a line On the other hand it is only for two node beam elements and it does not include moments Alternatively to giving concentrated loads of constant magnitude varying loads may be s
310. o in the DEFINE SPRING command Damping matrices of damper elements to be referred to in the DEFINE DAMPER command Mass matrices of mass elements to be referred to in the DEFINE MASS ELEMENT command PARAMETERS material name User given name for the material ANISOTROPIC Define an anisotropic material DAMPER Define the damping coefficients for a damper element ELASTIC Define an elastic material MASS Define the mass matrix for a mass element SPRING Define the stiffness of a spring element 5 175 Prefem SESAM 5 176 01 JUN 2003 Program version 7 1 PROPERTY MATERIAL material name ANISOTROPIC 2D ELEMENT ANISOTROPIC 3D SHELL ELEMENT SOLID ELEMENT PURPOSE The command defines data for an anisotropic material An orthotropic material being a special case of the anisotropic material may also be given PARAMETERS 2D ELEMENT Anisotropic material is to be specified for lower order 3 and 4 node shell elements or for membrane elements 3D SHELL ELEMENT Anisotropic material is to be specified for higher order 6 and 8 node shell elements SOLID ELEMENT Anisotropic material is to be specified for solid elements NOTES The appropriate type of element must have been set before being allowed to connect the anisotropic materi als 2D ELEMENT and 3D ELEMENT to surfaces For a more detailed description of anisotropic and orthotropic materials see Ref 4 SESAM Prefem Program version 7
311. oad force components of the complex load One of the two end points of the selected line the load is ap plied at a given distance from this point Distance from the selected point where the load is applied The BEAM CONCENTRATED load can only be used for lines for which two node beam elements are cre ated The given concentrated load is changed by the program into a very short line load The length or width and intensity of this line load is load width length of relevant beam element 0 001 load intensity given load load width If the given distance from the selected point to the load places the load within half the load width from the end of a beam element then the load is moved slightly so as to act on a single beam element Prefem SESAM 5 148 01 JUN 2003 Program version 7 1 PROPERTY LOAD load case COMPONENT PRESSURE COMPONENT PRESSURE select surfaces GLOBAL TRANSFORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam INSIDE SURFACE ipx ipy ipz MIDDLE SURFACE OUTSIDE SURFACE X Z EE EENE INSIDE LAYER END MIDDLE LAYER layer OUTSIDE LAYER PURPOSE The command defines component pressure loads pressure in x y and z component form on surfaces For shell elements the pressure is applied to the inside middle or outside surface of the elements For the concept of inside and outside
312. odies are named idBijk ijk is a number taken from the one of the surfaces bounding the body with the lowest ijk number e When cylindrical or spherical coordinate systems are employed such systems are implicitly defined and named idXijk where ijk 000 Such a coordinate system will be the same as if the DEFINE COORDINATE SYSTEM command created it and may be referred to by other commands e g the PROPERTY command When ten or more points are generated in a direction two digits will be used for that topological direction in forming the name A couple of examples AP0341 is the name of a point being the 3rd among 10 or more in I direction 4th in J direction and 1st in K direction AP030401 is the name of the same point when 10 or more points are generated for each of the three directions It is possible to force the names to contain two digits for any or all directions even though less than 10 points are generated This may be desired if two digits are necessary to maintain a consistent naming system after adding more geometry later on The id is used to achieve this For example rather than only giving the character A the id may be given as A amp IIJK This id involves that all geometry names will contain two digits for the I direction because there are two I s in the id but only one digit for the J and K directions The amp represents the character P for points I J K for lines etc If two digits are re
313. of surfaces see Section 3 12 3 The inside middle and outside layer is similar but is relevant for layered elements only For solid elements the inside middle and outside surface specification must be entered but the data is irrele vant and is not used Alternatively to giving constant pressure components varying pressures may be specified by functions see Section 5 3 PARAMETERS select surfaces Select surfaces See Section 5 1 on how to perform a selection GLOBAL The pressure components refer to the model s cartesian coordi nate system TRANSFORMED The pressure components refer to a previously defined transfor mation of the cartesian coordinate system see the command DEFINE TRANSFORMATION LOCAL COORDINATE SY STEM The pressure components refer to a previously defined cylin drical or spherical coordinate system see the command DE FINE COORDINATE SYSTEM SESAM Program version 7 1 UNTRANSFORMED trnam coord name px py pz ipx ipy Ipz INSIDE SURFACE MIDDLE SURFACE OUTSIDE SURFACE INSIDE LAYER MIDDLE LAYER OUTSIDE LAYER layer Prefem 01 JUN 2003 5 149 No additional transformation of the cylindrical or spherical coordinate system is performed Name of a previously defined transformation Name of a previously defined coordinate system Pressure components Imaginary pressure components By entering data for these the load will implicitly become a complex load Entering END rather than ipx ip
314. of terms to enter p is a function of the number of degrees of freedom of the damping matrix n as follows p n n 2 The default value of the terms outside the diagonal is zero mll m21 m22 mnl mn2 mnn SESAM Program version 7 1 Prefem 01 JUN 2003 5 187 PROPERTY MATERIAL material name SPRING AXIAL spring SPRING STIFFNESS R TO GROUND n kij p FLEXIBILITY PURPOSE The command defines the spring constant of an axial spring and the stiffness or flexibility matrix of a spring to ground The flexibility matrix is the inverse of the stiffness matrix PARAMETERS AXIAL spring TO GROUND n STIFFNESS FLEXIBILITY kij Define an axial spring Axial spring constant Define a spring to ground Number of degrees of freedom of the stiffness flexibility matrix Stiffness matrix is to be given Flexibility matrix is to be given Terms of the lower triangular part of the stiffness flexibility matrix The terms are given column by column i e k11 k21 kn1 k22 kn2 knn see the matrix be low The number of terms to enter p is a function of the number of degrees of free dom of the stiffness matrix n as follows p n ny2 The default value of the terms outside the diagonal is zero k11 k21 k22 knl kn2 knn Prefem SESAM 5 188 01 JUN 2003 Program version 7 1 PROPERTY POINT MASS POINT MASS select points pmtx pmty pmtz p
315. of the line end point Name of the point defining the end point of the line guiding point Name of the guiding point shapel shape2 Names of the two intersecting shapes These must previously have been defined nelm Number of elements to be created along the line See also the commands SET NUMBEROF ELEMENTS and SET MAX ELEMENT LENGTH NOTES The direction of the intersection going from start point to end point has consequence for the local coordi nate system of beam elements Xeuiding point shape2 Figure 5 20 Intersection Prefem 5 64 01 JUN 2003 DEFINE LAYERED LAYERED layered name PLATE STIFFENER END PLATE is followed by THICKNESS thickness MATERIAL material name ECCENTRICITY SHEAR FACTOR sh fact END STIFFENER is followed by SECTION SPACING section name INFINITE PLATE angle spacing MATERIAL material name ECCENTRICITY SHEAR FACTOR sh fact END ECCENTRICITY following both PLATE and STIFFENER is followed by ECCENTRIC CALCULATED NEGATIVE Z OFFSET LOCAL COORDINATE OFFSET dx dy dz NOT ECCENTRIC PURPOSE SESAM Program version 7 1 The command defines layered element types to be used for modelling stiffened plate structures Stiffened plates are modelled by describing the relevant plates and stiffeners The plates
316. ogging of program information when using an unedited command log file as a command input file 4 1 5 Files used by Prefem The file environment of Prefem is illustrated in Figure 4 2 The file extensions MOD JNL etc are given together with file descriptions SESAM Prefem Program version 7 1 01 JUN 2003 4 5 model file mod command log file journal jnl INPUT INTERFACE FILE Figure 4 2 The file environment of Prefem The files are The command log journal file JNL is an ASCII file on which all commands and data given to the program are logged This means that both data typed or clicked by the user and data read by the pro gram from a command input file will be logged However commands not changing the model and data base e g a command displaying data will not be logged The time of opening and closing the model file is also logged The file is very useful as a backup file both for verification purposes and for later use as a command input file The command log file can be read and modified by a text editor The command input file JNL is an ASCII file which may be read into the program The commands contained on this file will have the same effect as if they where given by the user directly A command input file is convenient for batch execution of Prefem see Section 4 1 7 The file is processed by using the command SET COMMAND INPUT FILE followe
317. ogram version 7 1 01 JUN 2003 5 259 LONG MENU MODE Suppress no commands within the limits of the selected filters MODELLING Filter for modelling features GEOMETRY Switch for geometry modelling PROPERTY Switch for property modelling LOAD Switch for load modelling MESH Switch for mesh modelling EXAMPLES The example below will suppress modelling features not related to geometry modelling of a frame and shell structure The SHORT MENU MODE qualifier makes only the most commonly used commands available SET TASK SHORT MENU MODE MODELLING GEOMETRY ONLY ELEMENT TYPE FILTER SOLID OFF END END Prefem SESAM 5 260 01 JUN 2003 Program version 7 1 SET TOLERANCE COORDINATES coord tol LOAD DIFFERENCE load tol TOLERANCE SNAP snap tol UNIT VECTOR unit vect tol PURPOSE The command sets tolerance values PARAMETERS COORDINATES coord tol LOAD DIFFERENCE load tol SNAP snap tol UNIT VECTOR unit vect tol Set the tolerance value for geometric operations The coordi nate tolerance value is used to check geometrical coincidence between coordinates e g when defining new points by the COPY command The tolerance should be set in accordance with the units used e g m or mm and the minimum distances between points Coordinate tolerance value in the same units as the coordinates The default value is 0 1 Set the tolerance for print of nodal values of loads The toler ance is
318. ogram version 7 1 01 JUN 2003 APPENDIX A 1 APPENDIXA TUTORIAL EXAMPLES The following tutorial examples are presented Midship section e Cylindrical tank with flat bottom and spherical top A1 Midship Section The line mode input required to create the model of Section 3 2 is presented below Set naming of geometry to be done automatically SET DEFAULT AUTOMATIC NAMING ON oe Define four points DEFINE POINT o 0 0 0 40 0 0 40 50 0 0 50 Define surface that will be the bulkhead DEFINE SURFACE PO1 PO2 PO3 POO PO1 Cut surface first horizontally and then vertically CUT ALL SURFACES INCLUDED PREDEFINED PLANE XY PLANE 18 CUT ALL SURFACES INCLUDED PREDEFINED PLANE XZ PLANE 15 Round off corner to form the bilge DEFINE ROUNDED CORNER LI3 LI5 10 CORNER Prefem SESAM APPENDIX A 2 01 JUN 2003 Program version 7 1 Move point down to form sloping outer deck CHANGE POINT PO3 DZ 2 Extrude and copy the bulkhead to form the complete midship section EXTRUDE SU3 SU6 SU8 COP LI1 LI7 LI2 LI5 LI16 LI12 LI10 EXT GLOBAL 2 15 0018 0 0 LINE TO SURFACE Assign thickness to surfaces PROPERTY THICKNESS ALL SURFACES INCLUDED 0 03 EXTS12 EXTS13 EXTS22 EXTS23 0 02 Define and assign material to surfaces plates and lines beams PROPERTY MATERIAL STEEL ELASTIC 2 1E11 0 3 7850 0 0 0 0 CONNECT MATERIAL STEEL ALL SURFACES INCLUDED ALL LINES INCLUDED
319. ola geometry curve e g a spline geometry curve e g a spline Figure 3 33 Straight 2 node truss and beam elements and curved 3 node beam element SESAM Prefem Program version 7 1 01 JUN 2003 3 39 3 4 4 2 D Elements for Surfaces The 2 D elements are the membrane shell including sandwich and layered and axi symmetric elements see Table 2 2 and Figure 2 3 Figure 3 34 through Figure 3 44 illustrate various types of mesh that may be created for surfaces A brief description is given below for each figure See also Figure 3 45 with corresponding note e Figure 3 34 illustrates how both quadrilateral and triangular elements may be used to create a mesh for a surface with four mesh comers The four borderlines are divided into 3 3 4 and 4 equally sized element edges Note that the mesh with triangular elements is created by first making a mesh with quadrilateral elements and then splitting each quadrilateral element into two triangular elements Figure 3 35 illustrates an alternative mesh for the same surface as in Figure 3 34 the only difference is that the number of mesh corners has been reduced to three Observe how the mesh is influenced by the number of mesh corners Figure 3 36 illustrates a mesh for the same surface now with only two mesh corners In this case the mesh becomes very distorted so for a quadratic surface this choice of mesh corners combined with dis cretisation data is obviously a bad one Figure 3 3
320. ometry See Section 5 1 on how to perform a selection select nodes Select nodes directly See Section 5 2 on how to perform a se lection GLOBAL The boundary conditions refer to the cartesian coordinate sys tem of the model TRANSFORMED The boundary conditions refer to a previously defined transfor mation of the cartesian coordinate system see the command DEFINE TRANSFORMATION LOCAL COORDINATE SYSTEM The boundary conditions refer to a previously defined cylin drical or spherical coordinate system see the command DE FINE COORDINATE SYSTEM trnam Name of a previously defined transformation coord name Name of a previously defined coordinate system UNTRANSFORMED The cylindrical or spherical coordinate system is employed without any further transformation NOTES Boundary conditions defined for geometry will automatically be transferred to the nodes of the geometry Whether boundary conditions are defined before or after creating the mesh has no consequence The ultimately given boundary condition will override any previously given boundary condition For exam ple if two lines meet in a point and the X translation only is fixed for the first line and the Y translation only is fixed for the second line then the node created in the common point will have the Y translation fixed only the fixations of the two lines are not added Note that deleting the mesh and re meshing will discard boundary conditions specified directly f
321. ommand except for initial displacements and velocities see below Loads are assigned to the geometry model and will automatically be transferred to the FE model deleting and recreating the FE mesh will not affect the loads However loads defined for geometry where there is no mesh will be ignored Loads are specified as constant values or as variables by use of functions and they may be given in the global the superelement s cartesian coordinate system or in user defined cylindrical or spherical coordinate systems The loads may also be given in transformed coordinate systems i e cartesian transformations with respect to the relevant cartesian cylindrical or spherical coordinate sys tem The load types are CONCENTRATED loads in points transferred to nodes as nodal loads BEAM CONCENTRATED loads on beam elements transferred as very short line loads SESAM Prefem Program version 7 1 01 JUN 2003 3 53 LINE LOAD on lines transferred as line distributed loads on either beam membrane or shell ele ments LINE MOMENT on lines transferred as line distributed loads on either three node beam or shell ele ments PART LINE on lines transferred as line loads on parts of either beam membrane or shell elements NORMAL PRESSURE on surfaces transferred as normal surface pressure on shell or solid elements COMPONENT PRESSURE on surfaces transferred as surface pressure in three components on shell o
322. ommand re displays the current view refreshes the screen This is relevant for example after chang ing the viewing position using the commands SET GRAPHICS EYE DIRECTION or ROTATE and to remove the previous load display after adding a new one PARAMETERS MESH Re display only the mesh GEOMETRY Re display only the geometry ALL Re display both mesh and geometry Prefem SESAM 5 208 01 JUN 2003 Program version 7 1 READ DXF file prefix file name NO INCLUDE THICKNESS YES MAX MESH CORNER ANGLE angle NO DXF SETTINGS CLOSED TO SURFACE ES READ POLYLINE MODE TO LINES TO NODELINE TO SPLINE INPUT INTERFACE FILE file prefix superelement number ON JOURNALLING MODE OFF PURPOSE The command sets parameters for and reads data from file There are two formats that can be read e SESAM Input Interface File T FEM containing a first level superelement The Input Interface File T file contains a FE model elements and nodes with properties and no geom etry information Therefore reading this file involves establishing a FE model in Prefem s database with no corresponding geometry Currently no modifications of the FE model may be done The model can thus be used for verification purposes only The Input Interface File may have been generated by preprocessors other than Prefem Prefem will still be able to print and display the data When the reading has been c
323. ommon surfaces for bodies Merging nodes created for different surfaces and bodies is therefore not required Note You are allowed to define overlapping lines curves If two neighbouring surfaces are defined with such overlapping lines curves rather than sharing a common line curve then a double set of nodes will be created involving that the surfaces will not be coupled there will be a crack in the model See Figure 3 32 for an illustration of this The same goes for neighbouring bodies defined with overlapping surfaces There will be overlapping lines curves and surfaces only when defined on purpose Neither of the features for automatic creation of geometry COPY GENERATE EXTRUDE etc will result in overlapping lines curves and surfaces Note If you are in doubt about whether you have double nodes in your model caused by overlap ping geometry or other then use the CHECK CLUSTERED NODES command to identify closely located nodes If such is undesired the mesh and possibly the geometry should be revised geometry FE model geometry FE model u J y HHH 7 d N HH single line connects surfaces single node double lines between common points double nodes Figure 3 32 Adjoining surfaces are defined by common lines Through the CHECK ELEMENT SHAPE command the shape of the elements may be checked This is rel evant for surface elements membranes and shells and for volume elements solids An unsatisfactory mesh may be deleted by the DELET
324. ompleted a message giving the number of nodes elements and load cases is printed e g 83 NODES READ 167 ELEMENTS READ 5 LOADCASES READ Click the Display Mesh and Zoom Fr buttons to see the mesh DXF format DXF which is a file format for exchanging 3D CAD data DXF originates from the CAD program AutoCAD A DXF file contains a number of items of which the following are interpreted and converted into Prefem data POINT LINE SESAM Program version 7 1 VERTEX Prefem 01 JUN 2003 5 209 2D POLYLINE sub type of POLYLINE 3D POLYLINE sub type of POLYLINE 3D POLYGON MESH sub type of POLYLINE cubic B spline surface type ARC 3DLINE 3DFACE INSERT BLOCK section referred to by INSERT The BLOCK section typically consists of other DXF entities The INSERT entity contains an insert position and scaling factor This enables deployment of the same BLOCK at different positions and possibly with different scaling factors PARAMETERS DXF file prefix file name DXF SETTINGS INCLUDE THICKNESS MAX MESH CORNER ANGLE angle POLYLINE MODE CLOSED TO SURFACE Read a geometry model stored in a DXF formatted file and cre ate a Prefem geometry model The geometric entities point line and surface are imported A log file is generated during the reading The log has file type LOG and will have the same name as the DXF file File name prefix
325. ons below for LX IY IZ WXMIN WYMIN WZMIN SHARY SHARZ and SHCENY are taken from Ref 1 The expression for SHCENZ is taken from Ref 2 HW HZ TT TB A TB HW TT 2 B TB HW 2 SESAM Prefem Program version 7 1 01 JUN 2003 APPENDIX B 11 C TB 2 AREA TY HW BT TT BB TB Y MAX BB 2 BT 2 Z BT TT A HW TY B BB TB C AREA TRA BT TT 12 BT OTPOHZLTT AOZY TRB TY HW 12 TY HW TB HW 2 zy TRC BB TB 12 BB TB TB 2 Z IX TT HW BT BB 1 27T 3 If TT TY and TT TB then WXMIN IX TT M jp 130 8T TT HW TY BB TB 3 WXMIN IX MAX TT TY TB IY TRA TRB TRC IZ TB BE HW TY TT BT 12 IYZ 0 WYMIN IY MAX HZ Z Z WZMIN 21Z MAX BB BT SZ TT BT TB BE HW TY 8 SHARY IZ SZ TB TT SFY SHARZ IY SY TY SFZ SHCENY 0 SHCENZ HZ TT 2 TT BT TB BB 2 TT BT TB BP Z CY BB 2 CZ Z Prefem SESAM APPENDIX B 12 01 JUN 2003 Program version 7 1 B1 6 L section B 1 6 1 Sectional Dimensions HZ Height TY Thickness of web BY Width of flange TZ Thickness of flange SFY Shear factor y direction SFZ Shear factor z direction POSWEB for web location in positive y direction otherwise 1 ti shear centre Negative Positive Figure B 6 L section B 1 6 2 Sectional Parameters Computed The expressions below for LX IY IZ WXMIN WYMIN WZMIN SHARY SHARZ and SHCENY are taken
326. oordinate system Mesh for a circular plane Mesh for a circular plane surface will be plane surface projected onto a sphere The border curves of Projection onto a sphere of a mesh lie in the spherical shape with borderlines curves on a cylinder will give distorted elements Figure 3 46 Projection of element meshes onto shapes Prefem SESAM 3 46 01 JUN 2003 Program version 7 1 3 4 6 3 D Elements for Bodies The 3 D elements are the solid elements see Table 2 2 A solid element mesh must be prismatic i e the meshes of the top and bottom surfaces must in terms of topology be equal This means that their correspond ing borderlines curves must have equal number of elements and they must have mesh corner and not mesh corner in corresponding points See Figure 3 47 Meshes of top and bottom surfaces must be equal in j i r terms of topology one to one pod correspondance between ine nodes and elements The element shapes may differ Figure 3 47 Mesh for solid elements must be prismatic 3 4 7 Changing the Mesh Created The mesh created may be altered by changing the element discretisation i e the number of elements along lines curves element sizes and the relative sizes of elements along lines curves Nodal coordinates may also be changed even though this should normally be avoided Changing the number of elements SET NUMBEROF ELEMENTS and element sizes SET MAX ELE MENT LENGTH will result in delet
327. or nodes It is therefore in general best to define boundary conditions as all other properties for geometry rather than nodes Prefem SESAM 5 130 01 JUN 2003 Program version 7 1 PROPERTY CHANGE BOUNDARY CONDITION INITIAL DISPLACEMENT INITIAL VELOCITY LINEAR DEPENDENCY LOAD CHANGE LOCAL COORDINATE BEAM MATERIAL POINT MASS SECTION THICKNESS TRANSFORMATION PURPOSE The command changes previously defined properties The command is equivalent to the CHANGE PROP ERTY command The commands have the same syntax and corresponding interpretation as the PROPERTY command defining the data Therefore rather than describing these commands in detail here reference is made to the corresponding PROPERTY command NOTES The PROPERTY CHANGE LOAD load case TO MASS command demands special explanation see the CHANGE PROPERTY LOAD load case TO MASS command If changes are made to loads by the PROPERTY CHANGE LOAD command then use the RE COMPUTE LOADS command to redistribute the loads otherwise an ADD DISPLAY LOAD command will not give the correct result This re computation will automatically be performed when producing the Input Interface File Rather than using the PROPERTY CHANGE TRANSFORMATION command the CHANGE TRANS FORMATION command is recommended as the latter is the more flexible and powerful one SESAM Program version 7 1 Prefem 01 JUN 2003 5 131 PROPERTY ECCENTRICITY
328. ordinate system This will be done SESAM Prefem Program version 7 1 01 JUN 2003 3 45 For surfaces defined by the GENERATE command in a cylindrical spherical coordinate system except when the surfaces become triangular instead of quadrilateral see the dome sector of Figure 3 17 the mesh must be projected onto a spherical shape even when the GENERATE command has been used For surfaces for which a cylindrical spherical coordinate system has been set by the SET MESH com mand Figure 3 46 illustrates the effect of projecting and not projecting various meshes onto shapes Generally the mesh for curved surfaces will have a tendency to sink in This because the iteration process creating the mesh seeks to minimise the potential energy of the surface Note that the nodes on the border lines curves will not be projected The borderlines curves of a surface should therefore lie in the shape onto which the surface is projected otherwise the elements on the edge of the surface will be distorted E N WE uem E A KAA ox V Lar AS SZ ER AT a AAKAAL lt gt y 7 v DUE ae me cS AS A a GE LA Regular meshes for cylinders Irregular meshes will sink Irregular meshes should be projected onto need not be projected in if not projected shapes in this case a cylinder E Alternatively the mesh may be created in a cylindrical spherical c
329. ositioned at a given vector away from the first point of the surface The guiding point is a fixed point positioned on the positive surface normal side The cartesian coordinates of the guiding point or the vector giv en in the cartesian coordinate system Reverse the current surface normal Surfaces for which the element normal will be changed See Section 5 1 on how to perform a selection SESAM Prefem Program version 7 1 01 JUN 2003 5 37 CHANGE POINT 3 X XY 4 POINT points lt update coordinates gt PURPOSE The command changes the coordinates of one or more points The lines defined based on these points will also change Coordinate values can be specified explicitly or by an update coordinates mode This mode is entered into and concluded by the arrow bracket less than and greater than commands lt and gt The coordinates of several points may be changed by selecting points by wild card selection The update coordinates mode may then be used to for example add or subtract a constant value to either of the coordi nates of the points PARAMETERS points Select points wild card parentheses and graphical means may be used to select several points Selecting points in the general way as described in Section 5 1 can however not be used here XYZ Are given as real numbers where x y and z are the cartesian coordinates of the point lt Enter into the update
330. ot be the same but the surfaces must have mesh corners and not mesh corners in corresponding positions This means that if say two lines of the bottom surface correspond to one line of the top surface then there must be a not mesh corner in between the two lines of the bottom surface See Figure 3 18 SESAM Prefem Program version 7 1 01 JUN 2003 3 23 The element mesh for a body must also be prismatic i e the meshes of the top and bottom surfaces must in terms of topology be equal their corresponding borderlines curves must have equal number of ele ments and they must have mesh corner and not mesh corner in corresponding points Further the mesh of the side surfaces must be regular with no mesh refinement and with mesh corners in the four points connecting with the top and bottom surfaces and only there sequence of definition of surface ST ST is top surface SB is bottom surface SS1 SS5 are side surfaces this cannot be a mesh corner Figure 3 18 Requirements to a body There are two commands for defining bodies DEFINE BODY DEFINE PRISM The difference between these two commands is that in the latter only the top and bottom surfaces are defined beforehand The DEFINE PRISM command thus involves implicit and automatic definition of the side surfaces by generation of straight lines between corresponding points of the top and bottom surfaces 3 3 2 Defining Shapes Shapes are tools in the form of surfaces used for def
331. pecification for K direction A GENERATE SURFACE A 1 3 n 141 n END CARTESIAN 0 0 O lt the starting point is in the origin 1 0 00 1 60 0 0 END lt the two vectors in I direction 0 0 3 0 0 0 0 7 0 0 1 1 0 END lt the three vectors in J direction V and v are the vectors in I direction Vj Vj and vj are the vectors in J direction AP24 Figure3 24 Generation of a 2 D geometry SESAM Prefem Program version 7 1 01 JUN 2003 3 31 Example 3 2 Generating a 3 D geometry The command below generates a 3 D geometry consisting of lines and points There will be 3 points in I and J directions and 2 points in K direction n n and n represent the number of elements to divide the lines into in a subsequent meshing The topological space is illustrated to the right The resulting geometry is displayed below Only point names are displayed topology 1 to 3 with step 1 in I 1 to 3 with step 1 in J 1 to 2 in K GENERATE LINEA 131m 13 1n 121m CARTESIAN 0 0 O lt the starting point is in the origin 3 0 0 0 2 0 7 0 3 END lt the two vectors in I direction 0 1 0 0 0 2 0 0 0 END lt the two vectors in J direction 0 0 2 5 END lt the single vector in K direction Z v and v are the vectors in I direction Vj and v are the vectors in J direction v4 is the vector in K direction Figure 3 25 Genera
332. pecified by func tions see Section 5 3 PARAMETERS line GLOBAL TRANSFORMED LOCAL COORDINATE SYSTEM UNTRANSFORMED trnam coord name fx fy fz Select a single line The load components refer to the model s cartesian coordinate system The load components refer to a previously defined transforma tion of the cartesian coordinate system see the command DE FINE TRANSFORMATION The load components refer to a previously defined cylindrical or spherical coordinate system see the command DEFINE COORDINATE SYSTEM No additional transformation of the cylindrical or spherical coordinate system is performed Name of a previously transformation Name of a previously defined coordinate system Load force components SESAM Program version 7 1 DEG PHASE ANGLE IMAGINARY COMPLEX RAD PHASE ANGLE END phx phy phz ifx ify ifz point distance NOTES Prefem 01 JUN 2003 5 147 The load is complex and given as amplitudes fx fy and fz and phase angles given in degrees phx phy and phz The load is complex and given as real values fx fy and fz and imaginary values ifx ify and ifz The load is complex and given as amplitudes fx fy and fz and phase angles given in radians phx phy and phz Entering END rather than any of the alternatives DEG PHASE ANGLE IMAGINARY COMPLEX and RAD PHASE ANGLE implies that the load is real Phase angles of the complex load Imaginary l
333. plane Allows specifying several cutting planes If given conclude the cutting by END The cutting plane is parallel with the cartesian X Y plane The cutting plane is parallel with the cartesian XZ plane The cutting plane is parallel with the cartesian YZ plane The cartesian Z coordinate of the cutting plane The cartesian Y coordinate of the cutting plane The cartesian X coordinate of the cutting plane Ifa line is used as cutting tool the line itself is not cut The line is only a tool and not a part of the geometry Table 5 1 Geometry to cut and tool to use Geometry line Tool point Cutting process The line is cut in two at the point The sum of number of elements for the two lines will be equal to the number of elements for the original line Element type is inherited from the original line See the COPY command for other properties car ried over from the original line line A new point is positioned at the intersection point The line being cut is handled as described above for line cut by point The line being the tool is not cut line plane shape A new point is positioned at the intersection point The line being cut is handled as described above for line cut by point surface line New points are positioned where the line cuts the borderlines of the surface The borderlines are cut as described above for line cut by point A new line is created between the two new points The sur
334. point2 and point3 each represent point name X y Z DEFINE POINT lt update coordinates gt PURPOSE The command cuts geometry e g a surface into two surfaces and a line into two lines Only planar cylindri cal and spherical surfaces created in a certain way may be cut See Section 3 3 4 about this PARAMETERS select surfaces select lines tool GENERAL PLANE point name DEFINE POINT xyz lt gt update coordinates Surfaces to be cut See Section 5 1 on how to perform a selection See Section 3 3 4 about which kinds of surface may be cut Lines to be cut See Section 5 1 on how to perform a selection Name cutting tool This may be a point line or a shape of type plane see Table 5 1 Use a plane defined by three points as cutting tool Name of an existing point Define a temporary point now The cartesian coordinates of the temporary point Enter into the update coordinates mode Conclude the update coordinates mode See the DEFINE POINT command for an explanation of this method for determin ing the coordinates of a point SESAM Program version 7 1 GRAPHICS drag mouse PREDEFINED PLANE REPEAT XY PLANE XZ PLANE YZ PLANE dz dy dx NOTES Prefem 01 JUN 2003 5 55 Cut by graphics means Press hold drag and release the mouse to make a line in the graphic display area for cutting the selected geometry Use as cutting tool a plane parallel with a cartesian
335. quired for all three direc tions then use A amp IIJJKK The geometry names will reflect the dimension of the topology space in that only the I and J values will be included in the names for a 2 D topology space and only the I values for a 1 D space For example AP34 is a point in a 2 D topology space and AP3 is a point in a 1 D space A topology range can be limited to a single value For example the start end and step values 1 1 and 1 the step value will in this case be irrelevant yield the range 1 The effect of specifying such a range for the Prefem SESAM 3 30 01 JUN 2003 Program version 7 1 K direction rather than defining a 2 D topology space is that the K value will be included in the geometry names For example a point will be named AP341 rather than AP34 If the names constructed by this convention are already in use by previously created geometry then default names will be created Example 3 1 Generating a 2 D geometry The command below generates a 2 D geometry consisting of surfaces l lines and points There will be 3 points in I direction and 4 points in J 2 3 direction n and n represent the number of elements to divide the 3 lines into 1n a subsequent meshing The topological space 1s I illustrated to the right The resulting geometry is displayed below Notice the system for naming the geometric entities topology 1 to 3 with step 1 in I direction 1 to 4 with step 1 1n J direction no s
336. r zoom area This may be done in two ways 1 Click twice once for each diagonal point 2 Press and hold in the first point drag and release in the sec ond point A rubber band will appear indicating the zoom area OFF The whole model not only the currently displayed part as is the case for the FRAME option will fill the display area The model will however not be re displayed i e the screen goes blank REDISPLAY OFF The same as the OFF option and in addition the model is dis played Prefem SESAM 5 264 01 JUN 2003 Program version 7 1 ALL number of commands PURPOSE The command initiates reading and execution of commands from a previously defined command input file See the SET COMMAND INPUT FILE command The program will read and execute commands until either e An end of file mark is detected The symbol is encountered or The requested number of commands have been read By giving number of commands 1 a single command will be read The command prompt gt will appear thereafter indicating that the following commands may be read and executed one by one by hitting carriage return This feature may prove useful for stepping through a command input file At any time the reading can be stopped by entering PARAMETERS ALL All commands on the command input file are read and executed number of commands Number of commands to be read and executed SESAM Prefem Pr
337. r an illustration of this mapping technique for a 2 D space only I J The requirement or rather an inescapable consequence of the command that all sur faces have the shape of parallelograms is also shown J surfaces all shaped as 4 parallelograms 3 lines 2 ints I poin 1 2 3 topological I J space vectors starting point X geometrical X Y space Figure 3 23 The GENERATE command maps a topology space into a geometry space A single GENERATE command will typically replace a number of commands for defining points lines surfaces and if relevant bodies i e a number of DEFINE POINT DEFINE LINE DEFINE SUR FACE and DEFINE BODY commands The structure of the command is as follows GENERATE level id topology coordinate system geometry Except for level and id the parameter names above each represent several parameters as detailed in the following The GENERATE command is described in principle below for a complete description see the command description in Chapter 5 level Determines the level of the geometry to be generated The options are POINT LINE SURFACE Prefem 3 28 topology coordinate system geometry SESAM 01 JUN 2003 Program version 7 1 BODY Generating lines involves generating points and lines generating surfaces involves generating points lines and surfaces and finally generating bodies involves gen erating points
338. r curved surfaces DEFINE SURFACE S5 Al A2 A3 To get the spherical mesh as shown to the right in Figure 3 17 the interior of the surface must be defined by projecting the surface onto a spherical shape This is done either within or after the command defining the surface These two alternatives are exemplified below SH1 is the name of a spherical shape with its centre and radius equal to those of the arcs Alt 1 DEFINE SHAPE SPHERE SH1 PO radius DEFINE SURFACE S5 Al A2 A3 SET PROJECTION S5 SH1 Alt 2 DEFINE SHAPE SPHERE SH1 PO radius DEFINE SURFACE S5 SH1 Al A2 A3 a concave spherical A2 mesh mesh i sinking in T j x x L radius gt Figure 3 17 Defining surfaces by projecting onto a shape Defining bodies Solid objects are modelled as bodies which by definition are enclosed by top and bottom surfaces and any number of side surfaces The following requirements to a body and its mesh must be met A body must logically if not geometrically be prismatic as shown in Figure 3 18 This implies that the side surfaces must be quadrilateral if not rectangular and extend from the bottom surface to the top surface In the command defining bodies the side surfaces must be given in sequence The top and bottom surfaces must have been defined in the same sequence starting and ending in corre sponding positions points lines The number of borderlines of the top and bottom surfaces need n
339. r solid elements TEMPERATURE loads for lines surfaces and bodies transferred to membrane shell and solid ele ments GRAVITY load transferred to all elements and giving inertia load according to material density and volume of elements RIGID BODY ACCELERATION and RIGID BODY VELOCITY load transferred to nodes RIGID BODY VELOCITY is currently not available in the analysis program Sestra PRESCRIBED DISPLACEMENT and PRESCRIBED ACCELERATION transferred to nodes for which boundary conditions are set accordingly Additionally there are a couple of properties defined directly under the PROPERTY command i e not under the PROPERTY LOAD command but which in effect are loading conditions for dynamic analysis INITIAL DISPLACEMENT transferred to nodes as an initial condition for a dynamic analysis INITIAL VELOCITY transferred to nodes as an initial condition for a dynamic analysis All elements loads are represented as nodal intensities Loads are assembled in load cases numbered from 1 and up Each load case may be comprised of several of the load types above The same load case may also contain the same load type more than once Specifying for example NORMAL PRESSURE twice for the same load case gives the same result as specifying the sum of the two pressures as a single NORMAL PRESSURE However a load case can only include one gravity load When defining a load the part of the model subjected to the lo
340. re point point 1 Name of the first point defining the linear value value 1 Value for the first point point 2 Name of the second point defining the linear value value 2 Value for the second point Example of use see Figure 5 8 LINEAR RADIUS VARYING PC P1 1 3 P2 2 P2 is a point on the outer sphere the value on the outer sphere 1s 2 The function for any line starting at PC will be the same P1 is a point on the inner sphere the value on the inner sphere is 1 3 Figure 5 8 Example of use of LINEAR RADIUS VARYING function SESAM Prefem Program version 7 1 01 JUN 2003 5 13 CYLINDRICAL ANGLE VARYING CYLINDER ANGLE VARYING axis 1 axis 2 point 1 value 1 point 2 value 2 PURPOSE The command defines a value varying linearly with the angle around a given axis The value is specified in two points Neither of the points can be on the axis and a line through the points cannot intersect the axis The function can be explained as follows Each of the two points define a radial plane about the axis These two radial planes form an angle The value will vary linearly about this angle starting in the radial plane defined by the first point point 1 and extrapolated up to 180 Past the 180 angle the value will vary line arly back to the given value in the radial plane defined by the first point The value will be constant in any radial plane PARAMETERS axis 1 Name of the f
341. remember that these are commands in themselves and must be separated from other commands and data by blanks The basic and mathematical functions above have parameters Rather than giving numeric values for these parameters another function may be given Le for all parameters called value value 1 etc in the follow ing explanations of the basic and mathematical functions a new function may be entered Furthermore arithmetric operators may be used to add subtract multiply and divide functions In this way functions of practically unlimited complexity may be specified The arithmetric operators are ek Prefem SESAM 5 8 01 JUN 2003 Program version 7 1 Normal operator precedence is applied i e is calculated first thereafter and while and are calcu lated last A function is in itself unlimited in space Its value in any given point in space in a node in the FE model is found by projecting the point into the function and evaluating the function there How to project a point into a function depends on the function and is explained in the following for each function Section 3 7 shows a few examples of load application by using functions Figure 5 1 through Figure 5 5 show a few more examples of functions The functions in the examples are explained in detail later in this section Pl 3 1 A linear variation along a line is defined by p LINEAR 2POINTS VARYING P1 6 4 P2
342. rent display BODY Add selected bodies to the current display select The parts to be added to the display This may be a selection of geometry see Sec tion 5 1 a selection of nodes or elements see Section 5 2 or a selection of shapes Selecting shapes is done in a similar way as selecting geometry Prefem SESAM 5 24 01 JUN 2003 Program version 7 1 GEOMETRY Add the geometry to the current display This command cannot be used after a DISPLAY MESH command Only the geometry related to the currently displayed elements nodes will be added FIND Highlight a single geometric entity geometry name The name of a single geometric entity point line surface or body MESH Add the mesh to the current display Only the mesh related to the currently dis played geometry will be added LOAD Add a selected load display to the current display The load is presented as arrows with their heads in the nodes where the load applies The arrow lengths are propor tional with the magnitude of the load The largest of the arrows will have a length on the display of approximately 15 mm this length may be adjusted by the SET GRAPHICS SIZE SYMBOLS LOAD ARROW SIZE command The tails of the arrows are connected by dotted lines the SET GRAPHICS PRESENTATION LOADS command removes these dotted lines Only the part of the load related to the currently displayed elements will be added The positions of the arrows are adjusted for shrunken elements for elem
343. resents the id A and the second represents P for points and I J and K for lines S T U for surfaces B for bodies The IJ represents a single digit for each of the topological I and J directions The mask name amp amp IIJJKK will be suitable for specifying maintenance of the naming system when cutting geometry consisting of names including two digits for each of the three topological directions The mask name amp amp amp IJKK SESAM Prefem Program version 7 1 01 JUN 2003 5 247 will be suitable for names including an id of two characters corresponding to the two first amp s and one digit for each of the topological directions I and J and two digits for the topological direction K To determine a new name there will be an interpolation in the extended numbering system above and the middle value is used Examples in between 2 and 4 3 is taken in between 2 and 6 4 is taken in between 5 and 6 F is taken All geometry names points lines surfaces and bodies matching the mask name will when cut result in new names following the system The example of Figure 5 57 illustrates its use AP12 ATI2 AP22 API2 AII2 APB2 AIB2 AP22 AJ21 AJI1 AUII AP21 APII Alll The surface AU11 to the left is cut and new points lines and surfaces are created and given names The mask name amp amp IJ has been specified New point names will be as shown to the right Line and surface names follow the new point
344. reserving i e the spline curve may differ from the corresponding polyline Read a FE model stored in a SESAM Input Interface File Number of the superelement to be read The file with the fol lowing name will be read file prefixTsuperelement number FEM Switch on off a mode involving logging of Prefem commands for creating the geometry and property thickness This in volves a translation of the information on the DXF file into Prefem commands These Prefem commands may be used to recreate the model at a later stage By default this mode is off involving that the READ DXF com mand is logged Thus the command log journal file cannot later be used without access to the DXF file Note that the mode is set to off after the READ command SESAM Prefem Program version 7 1 01 JUN 2003 5 211 ROTATE X AXIS ROTATE Y AXIS degrees Z AXIS PURPOSE The command rotates the display The rotations are about the axes specified by the command SET GRAPH ICS ROTATION MODE The global axes of the model are the default axes You may find that rotating the model interactively is more efficient see Section 3 1 PARAMETERS degrees Angle in degrees Prefem SESAM 5 212 01 JUN 2003 Program version 7 1 SET COMMAND INPUT FILE DEFAULT ELEMENT LENGTH RATIO ELEMENT TYPE GRAPHICS INSIDE JOURNALLING MAX ELEMENT LENGTH MESH MESH CORNER MESH PARAMETERS NAMING NOT MESH CORNER NUMBEROF ELEMEN
345. ric contact element 3 nodes 6 2 3 3NODE CONTACT per side INTER3A MEMBRANE 3NODES CSTA Constant strain triangle 3 3 MEMBRANE 4NODES LQUA Linear quadrilateral 4 3 MEMBRANE 6NODES ILST Isoparametric linear strain triangle 6 3 MEMBRANE 8NODES IQQE Isoparametric quadratic strain quadrilateral 8 3 AXISYMMETRIC 3NODES AXCS 3 2 AXISYMMETRIC 4NODES AXLQ Axi symmetric versions of the correspond 4 2 AXISYMMETRIC 6NODES AXLS ing membrane elements 6 2 AXISYMMETRIC 8NODES AXQQ 8 2 SHELL 3NODES FTRS Triangular flat thin shell 3 6 SHELL 4NODES FQUS Quadrilateral flat thin shell 4 6 SHELL DRILLING FTAS Triangular flat thin shell with drilling 3 6 3NODES degrees of freedom SHELL DRILLING FQAS Quadrilateral flat thin shell with drilling 4 6 4NODES degrees of freedom SHELL 6NODES SCTS cee curved triangular thin thick 6 6 SHELL 8NODES SCQS Subparametric curved quadrilateral thin g 6 thick shell 9 node reduced integration doubly curved SHELL 9NODES HCQS shell S9R5 9 6 SANDWICH 6NODES MCTS o LE sandwich element based 6 6 Prefem SESAM 2 6 01 JUN 2003 Program version 7 1 Table 2 2 Element types of Prefem Element type Short ee coe Description nodes per Name used in command name node Curved quadrilateral sandwich element SANDWICH 8NODES MCQS based on SCOS 8 6 LAYERED 6NODES LCTS Curved triangular layered shell based on 6 6 SCTS LAYERED 8NODES LCQS Curved quadrilateral
346. rientation of the T stiffeners of this model is achieved by the following commands PROPERTY LOCAL COORDINATE BEAM ZX PLANE TOWARDS FIXED POINT coordinates of centre point select lines PROPERTY ECCENTRICITY BEAM select lines CALCULATED POSITIVE Z OFFSET Note that a T section is created based on an I section by making the width of the flange in this case the bottom flange a fraction larger than the web thickness Give the thickness of the same flange a reasonable value Figure 3 48 Local coordinate system and eccentricities for internal stiffeners in tank If the local coordinate system is not defined manually an automatic definition will take effect as explained for the command For truss elements the local coordinate system has no consequence and may be neglected 3 5 3 Eccentricity for Beam Two and three node beams may have offsets or eccentric attachments to the nodes The PROPERTY ECCENTRICITY command defines such eccentricities for selected lines either as vectors from the nodes to the beam element ends and midpoint for 3 node beam or by an automatic feature in which the program determines the eccentricity required to let the beam section be welded or attached onto the surface of the plate or shell The automatic feature termed CALCULATED NEGATIVE Z OFFSET and CALCU LATED POSITIVE Z OFFSET in the command takes the sectional data and plate shell thickness into account these data therefore need to b
347. rink factor SIZE SYMBOLS VIEWPORTS number of viewports PURPOSE The command sets control parameters for the graphical features of the program Prefem 5 223 Prefem 5 224 PARAMETERS AUTOMATIC CHARACTER TYPE COLOUR CURVE DRAW DEVICE EYE DIRECTION HIDDEN INPUT SESAM 01 JUN 2003 Program version 7 1 Switch automatic displaying of all geometry created or changed ON or OFF Default for graphical user interface is ON and default for line mode user interface is OFF Choose between hardware and software type characters Hard ware characters are faster to draw but software characters may be better shaped and their sizes may be adjusted by the SET GRAPHICS SIZE SYMBOLS command Software characters are default Set multiple colours for display of load and thickness See sep arate explanation of the command Choose accuracy of drawing of curves For small models and when zooming in on a large model the FINE alternative may be useful For large models where displaying the model takes time the COARSE alternative will speed it up NORMAL is the nor mal default accuracy Choose appropriate type of graphics device Legal alternatives will depend on the hardware you are using X WINDOW is the default choice on most Unix computers while WINDOWS is the default choice for PCs Set the viewpoint for the model display The command speci fies the direction vector from origin to eye
348. rmines the coordinates of the first point generated The number of vectors for each topological direction will correspond to the number of points defined in the topology specification if four points are defined then three vectors are required The GENERATE command is somewhat complex A few examples will show how to use it and also demon strate its capabilities see Figure 3 24 through Figure 3 26 Naming convention The GENERATE command makes use of a system for naming the geometry generated The names of the geometrical entities will reflect both the type of geometry point line etc and the position in the topologi cal space The naming system is as follows SESAM Prefem Program version 7 1 01 JUN 2003 3 29 Points are named idPijk where ijk is a number reflecting the position of the point in the topological space An example AP341 here the id is A and the point is the 3rd in I direction 4th in J direction and 1st in K direction Lines are named idlijk idJijk idKijk The lines in the three topological directions are identified by the letters I J and K ijk is a number taken from the one of the two points defining the line with the lowest ijk number Surfaces are named idSijk idTijk idUijk The surfaces perpendicular to the three topological directions I J and K are identified by S T and U re spectively ijkis a number taken from the one of the lines bounding the surface with the lowest ijk number B
349. rn ing line load on membrane elements see the warning under NOTES below For shell elements the load is applied to the inside middle or outside surface of the elements For the con cept of inside and outside of surfaces see Section 3 12 3 For layered elements the load is applied to the mid dle layer of an identified layer number Alternatively to giving constant load components varying loads may be specified by functions see Section 3 3 PARAMETERS select lines Select lines See Section 5 1 on how to perform a selection GLOBAL The load components refer to the model s cartesian coordinate system TRANSFORMED The load components refer to a previously defined transforma tion of the cartesian coordinate system see the command DE FINE TRANSFORMATION Prefem SESAM 5 156 01 JUN 2003 Program version 7 1 LOCAL COORDINATE SYSTEM The load components refer to a previously defined cylindrical or spherical coordinate system see the command DEFINE COORDINATE SYSTEM UNTRANSFORMED No additional transformation of the cylindrical or spherical coordinate system is performed trnam Name of a previously defined transformation coord name Name of a previously defined coordinate system fx fy fz Load components ifx ify ifz Imaginary load components By entering data for these the load will implicitly become a complex load Entering END rather than ifx ify ifz implies that the load is real INSIDE SURFACE SHELL ELEMENT The
350. rr eere er eere ets 5 130 PROPERTY ECCENTRICITY BEAM onrada ann e AAT AA TAa een tenes errans en nens 5 131 PROPERTY HINGE paaa tecto Dette ertt o soueeesoustesaensulsonsads vasdatteavedieeapnernseadundes 5 133 PROPERTY INITIAL DISPLACEMENT iseeeeeeeeee eene eene takti ttrt enn nee n NEEE ee eerne seen nnns 5 135 PROPERTY INITTAE VBEEQOCGLEY 5 2 ete ahd cinch dotted eee eee dederas ede e E NN S 5 136 PROPERTY LINEAR DEPENDENCY ornaris iinei aie enne emen ee ECLA ATR see en seen e nas 5 137 PROPERTY LINEAR DEPENDENCY GENERAL NODE DEPENDENCY 5 138 PROPERTY LINEAR DEPENDENCY LINE LINE DEPENDENCY erre 5 139 PROPERTY LINEAR DEPENDENCY RIGID BODY DEPENDENCY cmmRR 5 141 PROPERTY LINEAR DEPENDENCY TWO NODE DEPENDENCY eer 5 142 PROPERTY LINEAR DEPENDENCY TWO POINT DEPENDENCY eee 5 143 PROPERTY LOAD tete tit ioc od e doe estet ee td ee cr a Bie 5 144 PROPERTY LOAD load case BEAM CONCENTRATED creen 5 146 PROPERTY LOAD load case COMPONENT PRESSURE eee eee 5 148 PROPERTY LOAD load case CONCENTRATED seeeeeneee nennen nennen nennen ennt 5 150 PROPERTY LOAD load case GRAVITY cccecccccccccssccccessecccesssceccesseeecessseccsessesesessuseecssseeeesens 5 152 PROPERTY LOAD load case HYDRO PRESSURE eene enne enenene 5 153 PROPERTY LOAD load case LINE LOAD seeeeeeene enne enm neennnrnnennnnnennnns 5 155 PROPERTY LOAD load case LINE M
351. rte sian coordinate system and pointing from end 1 of the element towards the guiding point If FROM TOWARDS FIXED POINT Cartesian coordinates of the guiding point select lines Select lines See Section 5 1 on how to perform a selection NOTES If a local coordinate system has been defined and either of the element nodes are repositioned then the local coordinate system may become erroneous the local x axis may change while the local y and z axes are fixed Introducing eccentricities may also cause this In such cases the local coordinate system must be redefined by the user Z bal vector from end 1 to guiding point balean GP defines local z x plane global Ylocal Figure 5 43 The local coordinate system defined by a guiding point SESAM Prefem Program version 7 1 01 JUN 2003 5 173 PROPERTY LOCAL COORDINATE SURFACE LOCAL COORDINATE SURFACE select surfaces GLOBAL TRANSFORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam PURPOSE The command defines local coordinate systems for layered elements only It has no effect for other ele ments The local coordinate system is used to give orientation to stiffeners of the layered element See the DEFINE LAYERED command also see Section 3 10 2 PARAMETERS select surfaces Select surfaces See Section 5 1 on how to perform a selection GLOBAL The local x axis of the element is define
352. rve given must ad join the first one point name Names of previously defined points surrounding the surface Conclude the list either by entering END or by giving the first point once more NOTES The sequence in which the lines curves or points are given when defining the surface has consequence for the local coordinate system of surface elements see Section 3 12 3 Prefem 5 90 SESAM 01 JUN 2003 Program version 7 1 DEFINE TRANSFORMATION TRANSFORMATION trnam IDENT MIRROR point point2 POINT NAMES start point end point centre ROTATE start point end point ANGLES degree P y line name DISPLACEMENTS disx disy disz TRANSLATE POINT MOVE from point to point SCALE scale x scale y scale z END PURPOSE The command defines geometrical transformations Transformations are used in copying geometric entities for defining boundary conditions and loads in transformed askew coordinate systems and for orientating spring to ground and damper to ground elements Transformations can be built up by using one or more of the four types of transformation mirror rotate translate and scale All transformations given for the same transformation matrix are chained in the given order The END alternative concludes the building up of the transformation matrix Do not abort the com mand by entering as the definition of the transformation will then be disc
353. s The thickness may be shown numerically or symbolically see the command SET GRAPHICS PRESENTATION ELEMENT THICKNESS Joint switch for point line surface and body names Switch for the number of elements the lines are divided into See SET NUMBEROF ELEMENTS and SET MAX ELE MENT LENGTH Line name switch Mass element name switch Material name switch Mesh corner symbol switch See Figure 5 36 Node number switch Node symbol switch See Figure 5 36 for an explanation of the various node symbols Point name switch Section name switch Spring name switch Supernode symbol switch See Figure 5 36 SESAM Prefem Program version 7 1 01 JUN 2003 5 109 SURFACE NAME Surface name switch SURFACE NORMAL Surface normal switch fixed translational degree of freedom blue line with crossbar fixed rotational degree of freedom blue double arrow with crossbar fixed translation and rotation blue double arrow with two crossbars mesh corner violet 90 angle symbol free node yellow diamond fixed node green diamond linearly dependent node blue triangle prescribed node white triangle supernode blue circle or more precisely octagon point symbol yellow x ET UN Figure 5 36 Symbols NOTES The size of the symbols and names is controlled by the command SET GRAPHICS SIZE SYMBOLS Element thicknesses eccentricities and section outlines are multiplied by a factor in order to be visible on the screen Thi
354. s for one end of the beam The eccentricity is a vector from the nodes to the beam ends The beam end is selected by selecting appropriate point If several lines have been selected wild card may be used to se lect the corresponding points The line names together with the wild card point name identify the appropriate points If the wild card point name does not match an end point of a selected line the eccentricity is not applied An error message will be given if the wild card point name does not match any line ends Wild card point name Prefem SESAM 5 132 01 JUN 2003 Program version 7 1 XYZ Eccentricity in beam element local directions pointing from the node to the beam end Functions as described in Section 5 3 except for VALUE BETWEEN and ONLY BETWEEN may be used NOTES If more than one PROPERTY ECCENTRICITY BEAM command is given for the same line then the last one of the commands CALCULATED NEGATIVE Z OFFSET CALCULATED POSITIVE Z OFFSET and LOCAL COORDINATE OFFSET will take effect Eccentricities given by the ONE END OFFSET command however will be added but only the last ONE END LOCAL OFFSET if there is more than one for the point The combined result of PROPERTY ECCENTRICITY BEAM commands is printed by the PRINT ELE MENT select element ECCENTRICITY command Use of the CALCULATED NEGATIVE Z OFFSET and CALCULATED POSITIVE Z OFFSET options assumes that the plate thickness and cross section have already been defined
355. s factor can be changed using the SET GRAPHICS SIZE SYMBOLS SECTION FACTOR command The factor may be set to values between 1 and 100 Loads drawn with their eccentricities will also use this factor Prefem SESAM 5 110 01 JUN 2003 Program version 7 1 LABEL COLOUR IDENTIFICATION DISCRETE VALUES ABOVE value tol THICKNESS value E SPECIFIED RANGES COLOUR IDENTIFICATION END MATERIAL OFF PURPOSE The command shows by colours the thickness of 2 D elements or the material name of 2 D and 3 D ele ments Up to 15 different colours are available The thicknesses and material types cannot be shown at the same time The command is best used in combination with the SET GRAPHICS PRESENTATION FILLED ELEMENTS ON command By default only the edges of the elements are drawn in colour A simplified way of drawing in hidden mode is employed implying that the SET GRAPHICS HIDDEN ON command normally need not be used PARAMETERS THICKNESS Colour 2 D elements according to their thicknesses Only one colour is used for each element When the thickness varies within an element the thickness in one of the nodes is shown for the whole element DISCRETE VALUES All discrete thickness values are coloured above a given value A tolerance is used to determine whether two slightly different values are to be presented as the same or not This option is convenient when different constant values have been speci fied
356. s follows PROPERTY LOAD 6 lt load type gt lt reference to geometry e g surface names gt cocus a linear squared parabolic function gt a LINEAR 2POINTS VARYING P1 0 P2 1 2 E uem a linear function gt LINEAR 2POINTS VARYING P1 0 P3 1 END where to apply the load SESAM Prefem Program version 7 1 01 JUN 2003 3 59 straight lines zero value along these lines Figure 3 54 2 D function 3 7 1 Evaluation of Functions A function is in itself unlimited in space Its value in any given point in space in a node in the FE model is found by projecting the point into the function and evaluating the function there How to project a point into a function depends on the function the LINEAR 2POINTS VARYING function is discussed below for illustration purposes Full explanations are found in Section 5 3 The LINEAR 2POINTS VARYING function is defined by specifying two geometry points The line between these two points is the projection line Any point on the projection line and its extension will have a value as defined by the function This value will also apply to all points in the plane perpendicular to the projection line and through the point in question See Figure 3 55 for an illustration of this Point node in FE model for which value is sought value l The intersection between the plane and surface S point I projection line Line perpendicular to proje
357. s for bodies when the Body button is depressed Set is merely a consequence of GUI consistency with other SESAM preprocessors and has lit tle relevance for Prefem Line mode input The upper line presents the last given input The lower line includes the prompt for input and data entered in line mode On PC you may paste Ctrl V text into the line mode input area SESAM Prefem Program version 7 1 01 JUN 2003 3 7 Cursor position feedback The names of geometry at or close to the cursor position are listed here If more than one geometric item is within the tolerance of the cursor position then all these will be listed in the sequence points lines surfaces bodies This Cursor position feedback only works when the Point Line Surface Body Direct access buttons are depressed This may be utilised as follows If you cannot tell which is which of line and surface names because there are several names listed you may click lift the line or surface button Then only surface names or line names will be listed Note While entering a command by the keyboard it is not possible to click buttons or commands until hitting the Return key or deleting all data typed This involves that if you inadvertently have entered a space character which you may overlook as you cannot see it clicking com mands as well as selecting nodes and elements by clicking will not work Hit the backspace a few times to delete the space
358. s inside pressure from liquid up to top of cylinder case 2 is nside pressure from gas PROPERTY LOAD 1 NORMAL PRESSURE A B LINEAR 2POINTS VARYING AP21 1000 BP12 0 0 END MIDDLE SURFACE END LOAD 2 NORMAL PRESSURE ALL SURFACES INCLUDED 2000 END MIDDLE SURFACE END o o9 oe Prefem SESAM APPENDIX A 6 01 JUN 2003 Program version 7 1 Change rotation of cylinder and top surfaces to change surface normal thereby making normal pressure act in proper direction CHANGE ROTATION OF SURFACE B C o oe Create the mesh MESH ALL The model is now complete SESAM Program version 7 1 APPENDIX B Prefem 01 JUN 2003 APPENDIX B 1 THEORY B1 Formulae for Sectional Parameters The formulae employed in Prefem for computing the sectional parameters for the various beam cross sec tions are given in the following The formulae are taken from Ref 1 Ref 2 and Ref 3 The following notation is used AREA IX IY IZ IYZ WXMIN WYMIN WZMIN SHARY SHARZ SHCENY SHCENZ SY SZ Cross sectional area Torsional moment of inertia about shear centre Moment of inertia about y axis Moment of inertia about z axis Product of inertia about y and z axes Minimum torsional sectional modulus about shear centre Minimum sectional modulus about y axis Minimum sectional modulus about z axis Shear area in the direction of y axis Shear area in the direction of z axis Shear centre location y component S
359. s material must be defined prior to defin ing the mass elements see the DEFINE MASS ELEMENT command this is in contrast with what is the case for other elements and their material The various materials defined are given unique names and the materials are then assigned to the appropriate geometry for which elements are created This assignment 1s performed by the CONNECT MATERIAL command by referring to the material names and geometry names Assigning materials to geometry for which no elements are created has no consequence 3 5 7 Boundary Condition The PROPERTY BOUNDARY command is used for defining the boundary conditions Note that individual degrees of freedom d o f s of the nodes may be given different types of boundary condition Also note that a boundary condition is always given for all six d o f of the nodes even in cases where only three d o f exist membrane and solid elements the superfluous boundary conditions are simply neglected The boundary conditions are Free the d o f is not fixed or given any other special boundary condition all d o f will be free for nodes not given any boundary condition Fix the d o f is fixed at zero displacement Prescribed displacement the d o f 1s given a prescribed displacement the value of the displacement is given in the PROPERTY LOAD command Prescribed acceleration the d o f is given a prescribed acceleration the value of the acceleration is given in the PR
360. s of the cross sections i e like solids SESAM Program version 7 1 SOLID SECTION LOAD ARROW CONNECTED ARROWS NUMERICAL MIDNODE ELEMENTS NORMAL SIMPLIFIED element size 2 x true stiffener spacing D true stiffener spacing proportionally increased true stiffener areas Prefem 01 JUN 2003 5 233 The plate and stiffener layers are drawn as for the OUTLINE AREA option see this except that no scaled stiffener cross sec tions are drawn and in addition the stiffeners are drawn as ex trusions of the cross sections i e like solids Select presentation mode for load display Load values are shown as arrows Load values are shown as arrows and with their tails connected Load values are shown as numerical values Select how to draw elements with mid nodes e g eight node shells elements The complete element is drawn Draw the elements as if no mid nodes exist This will speed up the display and may for example be used for a hidden mode display with many elements element size 2 x drawn spacing stiffener areas with element size drawn spacing gt true stiffener spacing Figure 5 55 Display of layered element SECTION option versus AREA option Prefem SESAM 5 234 01 JUN 2003 Program version 7 1 SET GRAPHICS SIZE SYMBOLS BODY NAMES BOUNDARY CONDITION SYMBOLS ELEMENT NORMAL ELEMENT NUMBERS ELEMENT THICKNESS ELEMENT TYPES FACTOR GEOMETRY NAMES LINE
361. s sectional geometry data computed data are printed SECTION NAME i LSECT SECTION NUMBER 1 SECTION TYPE H L SECTION HZI HEIGHT AT END 0 800000 TY WEB THICKNESS 0 030000 BY FLANGE WIDTH 0 400000 TZ FLANGE THICKNESS 0 030000 SFY SHEAR FACTOR Y DIRECTION 1 000000 SFZ SHEAR FACTOR Z DIRECTION 1 000000 K WEB LOCATION IN LOCAL Y DIRECTION POSITIVE AREA CROSS SECTION AREA 0 035100 IX TORSIONAL MOMENT OF INERTIA ABOUT SHEAR CENTRE 0 000010 IY MOMENT OF INERTIA ABOUT Y AXIS 0 002406 IZ MOMENT OF INERTIA ABOUT Z AXIS 0 000432 IYZ PRODUCT OF INERTIA ABOUT Y AND Z AXES 0 000584 WXMIN MIN TORSIONAL SECTION MODULUS ABOUT SHEAR CENTRE 0 000295 WYMIN MIN SECTION MODULUS ABOUT Y AXIS 0 004611 WZMIN MIN SECTION MODULUS ABOUT Z AXIS 0 001343 SHARY SHEAR AREA IN THE DIRECTION OF Y AXIS 0 008346 SHARZ SHEAR AREA IN THE DIRECTION OF Z AXIS 0 017675 SHCENY SHEAR CENTRE LOCATION FROM CENTROID Y COMPONENT 0 063248 SHCENZ SHEAR CENTRE LOCATION FROM CENTROID Z COMPONENT 0 263248 SY STATIC AREA MOMENT ABOUT Y AXIS 0 004083 SZ STATIC AREA MOMENT ABOUT Z AXIS 0 001553 CY CENTROID LOC FROM BOTTOM RIGHT CORNER Y COMPONENT 0 321752 CZ CENTROID LOC FROM BOTTOM RIGHT CORNER Z COMPONENT 0 278248 SECTION NAME BOX SECTION NUMBER 2 SECTION TYPE i BOX HZI HEIGHT AT END 0 600000 BY SECTION WIDTH 0 400000 TT UPPER WALL THICKNESS 0 020000 TY SIDE WALL THICKNESS 0 020000 TB LOWER WAL
362. screen If the program is used in graphic input mode the STATUS program is started Prefem 5 106 JOIN SESAM 01 JUN 2003 Program version 7 1 JOIN namel name2 PURPOSE The command joins two neighbouring bodies into a single body The two bodies must have a common sur face which can be either a top bottom or side surface in either of them The orientation of the top bottom surfaces is inherited from the body named first PARAMETERS namel name2 Name of a previously defined body to be joined with another body This will also be the name of the new common body Name of a previously defined body to be joined with the first body This name will disappear SESAM Prefem Program version 7 1 01 JUN 2003 5 107 LABEL ALL LABELS ON BEAM ELEMENT BODY NAME OFF BOUNDARY CONDITION S YMBOL COLOUR IDENTIFICATION DAMPER NAMES ELEMENT NORMAL ELEMENT NUMBER ELEMENT THICKNESS GEOMETRY NAMES LINE DIVISIONS LABEL LINE NAME MASS ELEMENT NAMES MATERIAL NAMES OFF MESH CORNERS NODE NUMBER NODE SYMBOL POINT NAME SECTION NAMES ON SPRING NAMES SUPER NODE SYMBOL SURFACE NAME OFF SURFACE NORMAL ON PURPOSE The command switches on and off certain labels or additional information related to the geometry or ele ment model A label switched on will appear in the display and remain on for all subsequent d
363. se this feature PARAMETERS GENERAL NODE DEPENDENCY LINE LINE DEPENDENCY RIGID BODY DEPENDENCY TWO NODE DEPENDENCY TWO POINT DEPENDENCY Defines linear dependencies between any degree of freedom d o f of a node and any other d o f s of any other nodes This specification will be lost with a DELETE MESH command Defines linear dependencies between all or selected d o f s of nodes created on a pair of lines The pair of lines must have the same location overlap Defines linear dependencies between all or selected d o f s of several nodes and a single node Defines linear dependencies between one node and two other nodes The nodes are selected by referring directly to node numbers This specification will be lost with a DELETE MESH command Defines linear dependencies between one node and two other nodes The nodes are selected by referring to geometry points Prefem SESAM 5 138 01 JUN 2003 Program version 7 1 PROPERTY LINEAR DEPENDENCY GENERAL NODE DEPENDEN CY GENERAL NODE DEPENDENCY indep dof beta indep node Em dep dof END ie dep node END END PURPOSE The command defines linear dependencies between any degree of freedom d o f of a node and any other d o f s of any other nodes This specification will be lost with a DELETE MESH command The braces and asterisks indicate that each d o f of a dependent node may be made
364. self and giving some key information Program version number and release date date of executable file Access date and time now Your user identification and other operating system and hardware related data Before you are allowed to continue i e start giving commands you must respond to the following requests for information General file name prefix A character string forming a part of by preceding the names of the files opened by the program It may and may not include a directory specification Model file name The name of the model file a binary data base file the command log journal file and other files opened by the program see Section 4 1 5 Old or new file Choose new when commencing modelling and old when continuing an earlier session i e the model file and command log file already exist 4 1 4 Line Mode Input of Commands and Arguments Having successfully entered Prefem as explained in Section 4 1 3 the command prompt appears the character The window in which you are now working is called the line mode window You may switch to the graphical user interface explained in Section 3 1 by the line mode command SET GRAPHICS INPUT ON or you may continue working in the line mode window displaying the model will then open a display window The information below is about entering line mode commands Note that line mode commands may also be en
365. sitive Zr side Y 7 forms together with Xy and Zy a right handed cartesian coordinate sys tem See Figure 5 54 Global coordinates of the second point Global coordinates of the guiding point Define a rotation about given axes One or more rotations about the GLOBAL or LOCAL axes may be defined Rotations about the GLOBAL axes refer to the fixed cartesian coordinate system of the model Rotations about the LOCAL axes refer to the axes of the current transformed coordinate system A rotation is performed about an axis of the cartesian coordinate system of the model A rotation is performed about an axis of the current transformed coordinate system SESAM Prefem Program version 7 1 01 JUN 2003 5 205 XYZ The rotation is about the X Y or Z axis respectively Figure 5 54 Defining a transformation using the GUIDING POINT option Prefem SESAM 5 206 01 JUN 2003 Program version 7 1 RE COMPUTE RE COMPUTE LOADS PURPOSE The command re computes or re distributes the loads to nodes and elements When changes have been made to the loads or mesh this command may be used to re distribute the loads A load display may otherwise be incorrect A re computation will always be performed when the Input Interface File is produced PARAMETERS LOADS Redistributes the loads SESAM Prefem Program version 7 1 01 JUN 2003 5 207 RE DISPLAY MESH RE DISPLAY GEOMETRY ALL PURPOSE The c
366. stem is performed Name of a previously defined transformation Name of a previously defined coordinate system Constant load force components i e functions cannot be giv en The load is complex and given as amplitudes fx fy and fz and phase angles given in degrees phx phy and phz The load is complex and given as real values fx fy and fz and imaginary values ifx ify and ifz The load is complex and given as amplitudes fx fy and fz and phase angles given in radians phx phy and phz Entering END rather than any of the alternatives DEG PHASE ANGLE IMAGINARY COMPLEX and RAD PHASE ANGLE implies that the load 1s real Phase angles of the complex load in degrees or radians de pending on the chosen option Imaginary load force components One of the two end points of the selected line the load starts at a given distance from this point Distance from the first selected point where the load starts The other of the two end points of the selected line the load ends at a given distance from this point Distance from the second selected point where the load ends The load applies to the inside of shell surfaces The load applies to the middle of shell surfaces The load applies to the outside of shell surfaces The load applies to beam elements Prefem SESAM 5 162 01 JUN 2003 Program version 7 1 MEMBRANE ELEMENT The load applies to membrane elements MIDDLE LAYER LAYERED ELEMENT The load app
367. symbol rho density Table B 1 Examples of consistent units time unit is second Typical program input values Length unit Mass unit Force unit Density of steel Young s modulus for steel L M ML T Mass Volume Force Area M L M L T m kg EN 7 85 10 2 10 10 m lO kg 1t 10 N 7 85 2 10 108 cm kg 107N 7 85 10 2 10 10 cm lOkg 1t l0N Ikgf 7 85 106 2 10 10 mm kg 10 N 7 85 106 2 10 108 mm lOkg 1t 1N 7 85 10 2 10 10 cm 10 kg IN 7 85 10 2 10 107 m 10 kg 1 tonnef 10000 N 7 85 10 2 10 107 cm 10 kg 1 tonnef 10000 N 7 85 10 2 10 10 mm 107 kg 1 tonnef 10000N 7 85 10713 2 10 m 10 kg l kgf 10N 7 85 10 2 10 1019 cm 10 kg l kgf 10N 7 85 10 2 10 10 mm 10 kg 1 kgf 10N 7 85 1071 2 10 10 SESAM Prefem Program version 7 1 01 JUN 2003 REFERENCES 1 REFERENCES 1 W Beitz K H K ttner Dubbel Taschenbuch f r den Maschinenbau 17 Auflage 17th ed Springer Verlag 1990 2 Arne Selberg Stalkonstruksjoner Tapir 1972 3 S Timoshenko Strength of Materials Part I Elementary Theory and Problems Third Edition 1995 D Van Nostrand Company Inc 4 R M Jones Mechanics of Composite Materials Hemisphere Publishing Corporation 1975 Prefem SESAM REFERENCES 2 01 JUN 2003 Program version 7 1
368. t gt point name MOVE BY TRANSFORMATION trnam POINT INTERPOLATION point point2 factor SHAPE INTERSECTION shapel shape2 shape3 coord name USE LOCAL COORDINATE SYSTEM GLOBAL When a shift from the cartesian coordinate system of the model which is used by default to cylindrical or spherical coordinate systems is done by the USE LOCAL COORDINATE SYSTEM command then the set of commands DX DY DZ X Y Z are substituted by either of the sets DR DPHI DZ R PHI Z DR DPHI DTHETA R PHI THETA PURPOSE The command defines the geometric entity point by updating or modifying a set of current coordinates The current coordinates are whenever updated given in the message window on PC and in the line mode win dow on Unix The initial current coordinates after giving the lt command will normally be those of the last point defined The coordinates may repetitively be updated until the update coordinates mode is concluded by the gt command The update coordinates mode allows use of previously defined parameters See the DEFINE PARAMETER command PARAMETERS lt Enter into the update coordinates mode gt Conclude the update coordinates mode DX DY DZ Update cartesian coordinates by adding to the current values Correspondingly for cylindrical and spherical coordinate sys tems Prefem 5 74 dx dy dz XYZ XYZ point name MOVE BY TRANSFORMATION trnam POINT INTERPOLATION point
369. t for relevant geometry SET ELE MENT TYPE and then creating the FE mesh MESH ALL see Section 3 4 1 Properties like material Prefem SESAM 3 64 01 JUN 2003 Program version 7 1 thickness etc may then be defined For certain elements the approach is somewhat different in that the appropriate material must have been defined before the elements can be created These elements are the spring damper and mass elements plus the layered and sandwich elements multilayered elements See Section 3 10 1 and Section 3 10 2 respectively Furthermore certain rules must be obeyed when creating axi symmetric elements see Section 3 10 3 3 10 1 Spring Damper and Mass Elements Spring damper and mass elements are defined by the following sequence of commands PROPERTY MATERIAL mat name After giving the material name the material kind is selected Rather than selecting ELASTIC which is normally used the following options are available SPRING DAMPER MASS For the SPRING and DAMPER alternatives the options AXIAL and TO GROUND are available for the MASS alternative the option ONE NODED is available Thereafter data defining the material is given Then the elements are defined by the DEFINE command in which the appropriate of the following alter natives should be chosen SPRING DAMPER MASS ELEMENT Note that the SET ELEMENT TYPE command is not used 3 10 2 Sandwich Elements and Layered Elements
370. ta was entered at the end of the command that defined the transformation See the DEFINE TRANSFORMATION command or the PROP ERTY TRANSFORMATION command Rather than using the CHANGE PROPERTY TRANSFORMATION command the CHANGE TRANS FORMATION command is recommended as the latter is the more flexible and powerful one Wild card selection of geometry cannot be done for several of the CHANGE commands SESAM Prefem Program version 7 1 01 JUN 2003 5 27 CHANGE ARC INTERSECTION LINE SPLINE NODE LINE See the DEFINE command for the command syntax PURPOSE The command changes the definition of lines curves Any of the commands CHANGE ARC INTERSECTION LINE SPLINE NODE LINE can be used for changing any line and curve defined by the DEFINE ARC INTERSECTION LINE SPLINE NODE LINE or the GENERATE commands This is done by using e g the CHANGE ARC command for a line defined by DEFINE LINE The line curve then changes type as well as geometry the points defining it Such a change can be done even when the line curve is one of the borderlines of a surface on condition that the start and end points remain the same Also see Section 3 3 1 Note that wild card notation cannot be used for changing several lines curves Note A curve resulting from using the GENERATE command in cylindrical or spherical coordinate systems cannot be changed directly into a straight line using the CHANGE LINE command This is because the curve is alr
371. te points id Identification of the geometry to generate Using a single character A B will I start I end I step I el J start J end J step J el K start K end K step K el normally be adequate See Section 3 3 7 for more details The topology in I direction A start value an end value and a step value defines the range I start must be equal to or greater than 1 I end must be equal to or greater than I start I step must be equal to or greater than 1 The stepping incrementing does not need to hit the end value For example the start end and step values 3 10 and 2 yield the range 3 5 7 9 Number of elements assigned to each line in I direction The topology in J direction See the explanation for the I direction above Number of elements assigned to each line in J direction The topology in K direction See the explanation for the I direction above Number of elements assigned to each line in K direction Prefem 5 104 END coord name CARTESIAN CYLINDRICAL SPHERICAL orig x orig y orig z Zaxi x zaxi y Zaxi z raxi x raxi y raxi z x0 y0 z0 REPEAT n times dxI dyI dzI dxJ dyJ dzJ dxK dyK dzK NOTES SESAM 01 JUN 2003 Program version 7 1 By giving END rather than entering topology information for the J direction the to pology space is restricted to 1 D By giving END rather than entering topology in formation for the K direction the topology space is restricted to 2 D Na
372. ted elements Select elements for printing See Section 5 2 on how to perform a selection Print basic element type information Print information on element eccentricities Print information on the element local coordinate systems Print information on selected nodes Select nodes for printing See Section 5 2 on how to perform a selection SESAM Program version 7 1 COORDINATES BOUNDARY CONDITIONS LINEAR DEPENDENCY INITIAL CONDITIONS MASS LOAD load case ALL ALL LOAD TYPES load type LAYERED MATERIAL SECTION name TRANSFORMATION trnam DECODED UNDECODED NOTES Prefem 01 JUN 2003 5 119 Print nodal coordinates Print nodal boundary conditions Print linear dependencies of nodes Print initial conditions of nodes Print nodal masses Print information on selected loads Select load case for printing Select all load cases for printing Print information on all load types for selected load cases Type of load for the selected load cases for which to print infor mation See the PROPERTY LOAD command for the different types of loads Print information on selected layered names Print information on selected material names Print information on selected section names Name of layered material section to be printed Print information on selected transformation names Transformation name to print Print the transformations in decoded form i e in terms of trans lations and rotations
373. tered in the graphic mode window The information below is with a few exceptions therefore also rele vant for the graphical user interface The syntax and characteristics of line mode input are as follows The parameters commands sub commands and data are separated by one or more blank characters or a comma and may be entered one by one or with two or more entries on a single line of input For exam ple COMMAND SUB COMMAND SUB SUB COMMAND data Prefem SESAM 4 4 01 JUN 2003 Program version 7 1 is equivalent to COMMAND SUB COMMAND SUB SUB COMMAND data Note however that data belonging to different data sets cannot be entered on a single line UPPER CASE lower case all commands will be logged on a command log file in UPPER case Commands and sub commands may be abbreviated as long as they are unique In a command consisting of words separated by hyphens each word may be abbreviated or completely left out Examples NODE NUMBERS N N COMMAND INPUT FILE C I Default values are provided between slashes default The defaults are accepted by hitting Return Real or integer input may be entered irrespective of type of numerical data use E for exponent e lt will list all legal commands and data options This command is irrelevant for the graphical user inter face where all legal commands and data options are at any time given in the command column of the graphic mode window e
374. terial names default colour is the same as the relevant geometry name line surface body Set colour for FE mesh elements default colour is medium red Set colour for mesh corner symbols default colour is medium violet Set colour for node numbers default colour is medium green Set colour for free node symbols the diamond for nodes with no boundary condition default colour is medium yellow Set colour for point names default colour is light blue Set colour for point symbols the X default colour is medium yellow Set colour for supernodes nodes for which one or more d o f s are defined as super default colour is medium blue Set colour for surface names default colour is medium violet For these two colours there is no choice between light medi um and dark For these colours there is a choice between light medium and dark Choose colour intensity LIGHT may be the best choice for black background screen and DARK the best for white back ground plots SESAM Prefem Program version 7 1 01 JUN 2003 5 229 SET GRAPHICS NUMERICAL VALUES E FORMAT FORMAT NUMERICAL VALUES F FORMAT NUMBER OF DECIMALS number of decimals PURPOSE The command chooses format and number of decimals for numerical values shown in the display By default two decimals and F format is used PARAMETERS FORMAT Select format for numerical values E FORMAT E format is selected Example
375. termine the position of the polygon segment Apply the above graphical selection methods as follows Select a point and line curve by the item itself or its label Prefem SESAM 3 4 01 JUN 2003 Program version 7 1 Select a surface by rubberband polygon around it or by clicking its label You may also use the right mouse button RMB and left mouse button LMB in combination as follows Click the RMB once on a borderline curve of the surface and see that the line curve is highlighted changing colour Without moving the mouse click the RMB once more and an adjoining surface is high lighted If this is the desired surface then click the LMB If not then keep clicking the RMB until the desired surface is highlighted whereupon the LMB is clicked Note that all clicks with the RMB and LMB should be done without moving the mouse or at least not more than a set frac tional distance Select a body in the same way as explained above for a surface When the RMB is repeatedly clicked and after highlighting all adjoining surfaces the adjoining bodies will be highlighted one after another Note that you cannot loop through the geometrical entities more than once i e after highlighting the last body clicking the RMB will no longer have any effect The availability of graphical selection is subject to that geometry selection has been switched on by the Direct access buttons Point Line Surface and Body By default they are
376. the DEFINE ARC command must be less than 180 degrees DEFINE INTERSECTION command must be less than 360 degrees 2 7 2 Constraints on Deleting Geometry Surfaces cannot be deleted if bodies are defined based on the surfaces Lines curves cannot be deleted if surfaces are defined based on the lines curves Points cannot be deleted if lines curves are defined based on the points 2 7 3 Constraints on FE Mesh Node and element numbers are automatically assigned by Prefem during creation of the FE mesh and cannot be changed by the user the modelling principles implies that he will have no reason for doing so SESAM Prefem Program version 7 1 01 JUN 2003 2 9 A maximum of four mesh corners are allowed for a surface see Figure 3 31 An exception is when there is only one single element between two mesh corners see Figure 3 39 Ifthe sum of the numbers of elements for all lines curves surrounding a surface is an odd number then a triangular element is automatically inserted in the sharpest corner The user may overrule this by select ing any corner for the triangular element See the illustration of Figure 2 4 There are cases where a FE mesh logically cannot be created e g when many elements are requested for one side or for two adjoining sides compared with the number of elements for other sides of a quadrilat eral A too high degree of mesh refinement is requested See the illustration of Figure 2 5 The soli
377. the latter must also be assigned or connected to the relevant lines Having followed this procedure and automatically calculated the eccentricities neither changing the plate thickness nor deleting the plate elements will have any direct effect on the eccentricities The beam elements must be deleted and re created or the PROPERTY ECCEN TRICITY BEAM command must be issued once more to change the eccentricities nodes section through shell and beams section through shell and beams with no eccentricities after CALCULATED NEGATIVE Z OFFSET Figure 5 37 Automatically calculated eccentricity for L and I sections SESAM Prefem Program version 7 1 01 JUN 2003 5 133 PROPERTY HINGE HINGE select lines point GLOBAL TRANSFORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam LOCAL BEAM COORDINATE SYSTEM FIXATION alphai 6 ci STIFFNESS 6 INFINITY PURPOSE The command introduces hinges for two node beam elements The hinge is defined for one end of a beam element at the time Any d o f may be defined as a hinge including the translational d o f s Furthermore stiffnesses may be attached to the hinges These stiffnesses are either given as coefficients of fixation 04 or as elastic spring stiffnesses c The relationship between and c is 0 ci ki c where k is the diagonal term of the stiffness matrix corresponding
378. the parameter value The value of the parameter May also be given as an expression see Section 3 5 10 NOTES Note that the command DEFINE POINT point parameter is not allowed This because the parameter may only be used in situations where a real value is the only alternative available and not for example END Prefem SESAM 5 72 01 JUN 2003 Program version 7 1 DEFINE POINT y Z POINT name update coordinates gt PURPOSE The command defines the geometric entity point The coordinates are specified either explicitly by giving x y and z in the cartesian coordinate system of the model or by an update coordinates mode This mode is entered into and concluded by the arrow bracket less than and greater than commands lt and gt This mode is explained in detail on the following pages PARAMETERS name XYZ lt gt update coordinates NOTES User given name of the point The cartesian coordinates of the point Enter into the update coordinates mode Conclude the update coordinates mode See following pages Two points cannot have the same coordinates or more precisely they cannot have the same coordinates within the given coordinate tolerance See the SET TOLERANCE command SESAM Prefem Program version 7 1 01 JUN 2003 5 73 DEFINE POINT name lt update coordinates gt DX dx DY dy DZ dz X X Y Jy Z Z l
379. theses EXCLUDE Exclude geometry names from geometry already selected INCLUDE Include geometry names this is relevant after an EXCLUDE command in order to counteract the exclusion WITH Of the geometry currently selected within the current com mand only the part with the appropriate characteristics are se lected MATERIAL The given material name is the criterion for selection SECTION The given section name is the criterion for selection Prefem SESAM 5 4 01 JUN 2003 Program version 7 1 THICKNESS The lower and upper limit for thickness is the criterion for se lection Functions cannot have been used for specification of the thickness for this option to work 5 2 Selecting Nodes and Elements In accordance with the philosophy of Prefem the user will normally only refer to geometric entities In cer tain cases however selecting nodes and elements directly may be needed e g within the DEFINE SET and DISPLAY commands The command syntax for selecting nodes and elements is described below In cases where selecting only elements and not nodes is relevant then only the relevant options will be available In the command description the texts select elements and select nodes should be understood as the fol lowing command syntax name of geometry node i NODE NUMBER END NODE GROUP nodel node2 nstep ALL NODES INCLUDED element END ELEMENT GROUP elem1 elem2 estep ALL ELEMENTS INC
380. they can all be switched on and off by LABEL NODE SYMBOL ON OFF PARAMETERS FIXED NODES Switch on or off symbol for fixed nodes green diamond FREE NODES Switch on or off symbol for free nodes yellow diamond LINEAR DEPENDENT NODES Switch on or off symbol for linearly dependent nodes blue tri angle PRESCRIBED NODES Switch on or off symbol for prescribed nodes whether it be pre scribed displacements or prescribed accelerations white trian gle SUPER NODES Switch on or off symbol for supernodes blue circle or more precisely octagon NOTES If a node has a combination of boundary conditions the symbol chosen for the node will be according to the following precedence supernode linearly dependent prescribed fixed free The number of degrees of freedom having a particular boundary condition is of no importance for the choice of symbol E g a node may have five degrees of freedom fixed but if only a single degree of freedom is super then the node will be labelled as a supernode Prefem SESAM 5 112 01 JUN 2003 Program version 7 1 LOCATE LOCATE PURPOSE The command adds the geometry using dotted lines to the current display The LOCATE command is useful for locating the currently displayed part of the complete model either a geometry display or mesh display SESAM Prefem Program version 7 1 01 JUN 2003 5 113 MESH name of geometry ADJUST select surfaces ALL MESH CRACK
381. those of the originals But since this is not allowed default names will be used for all new geometric entities COPY AU123 T3 In the following command surface AU123 with all its lines and points will be copied The names of the new geometric entities will be the same as those of the originals only replacing the last character by 5 COPY AU123 amp amp amp amp 5 T4 In the following command surface AU123 with all its lines and points will be copied The names of the new geometric entities will be the same as those of the originals only replacing the A by a D and the last charac ter by 6 COPY AU123 D amp amp amp 6 T5 SESAM Prefem Program version 7 1 01 JUN 2003 5 51 CREATE CONNECTOR CRACK CREATE DESCRIPTION MESH SUPERELEMENT a This option is presently inactive b This option is presently inactive c This option is presently inactive PURPOSE The commands create data PARAMETERS DESCRIPTION Create a description for a material name a cross section name or a set MESH Create the FE mesh Prefem SESAM 5 52 01 JUN 2003 Program version 7 1 CREATE DESCRIPTION text END DESCRIPTION name PURPOSE The command creates a description for material names section names and sets These must previously have been defined by the commands PROPERTY MATERIAL PROPERTY SECTION and DEFINE SET respectively Creating descriptions is solely for docu
382. tion of a 3 D geometry Prefem SESAM 3 32 01 JUN 2003 Program version 7 1 Example 3 3 Generation of a 3 D geometry in cylindrical coordinate system The command below generates a 3 D geometry consisting of bodies surfaces lines and points There will be 2 points in I direction 3 points in J direction and 2 points in K direction n n and n represent the number of elements to divide the lines into in a subsequent meshing The topological space is illustrated to the right Note that the vectors are given in the cylindrical coordinate system R Gb Z The resulting geometry is displayed below Only point names are displayed topology 1 to 2 in I 1 to 3 with step 1 in J 1 to 2 in K GENERATE BODY A 12 1n 131n 121m CYLINDRICAL 0 0 0 0 0 1 1 0 0 lt the coordinate system Tz 0 3 lt the starting point is in R 1 0 Z 0 1 0 0 0 END lt the single vector in I direction 0 3 30 0 0 4 40 0 0 0 END lt the two vectors in J direction 0 5 0 1 END lt the single vector in K direction Z wand v are the vectors in I direction Vj and v are the vectors in J direction v 18 the vector in K direction starting point cylindrical coordinates 1 0 0 Figure 3 26 Generation of a 3 D geometry in cylindrical coordinate system SESAM Prefem Program version 7 1 01 JUN 2003 3 33 3 3 8 Extruding Geometry See Section 3 3 9 for a brief discussion on the
383. tion the direction of the surface normal is defined by a guiding point This guiding point may be defined by giving its coordinates directly or by positioning it infinitely far away along any of the global axes either in positive or in negative direction The guiding point lies on the positive surface normal side This is however not true for the FROM FIXED POINT alternative which involves that the guiding point lies on the negative surface normal side PARAMETERS NORMAL OF SURFACE Set the surface normal explicitly X GLOBAL INFINITY The guiding point is positioned infinitely far out along the pos itive global X axis Y GLOBAL INFINITY The guiding point is positioned infinitely far out along the pos itive global Y axis Z GLOBAL INFINITY The guiding point is positioned infinitely far out along the pos itive global Z axis Prefem 5 36 X GLOBAL INFINITY Y GLOBAL INFINITY Z GLOBAL INFINITY FROM FIXED POINT GUIDING POINT DIRECTION TOWARDS FIXED POINT XYZ ROTATION OF SURFACE select surfaces SESAM 01 JUN 2003 Program version 7 1 The guiding point is positioned infinitely far out along the neg ative global X axis The guiding point is positioned infinitely far out along the neg ative global Y axis The guiding point is positioned infinitely far out along the neg ative global Z axis The guiding point is a fixed point positioned on the negative surface normal side The guiding point is p
384. tity matrix as dummy transformation The local x axis of the element is defined by the projection onto the element of the R axis of a cylindrical or spherical coordi nate system Such coordinate systems must previously have been defined by the DEFINE COORDINATE SYSTEM com mand The cylindrical spherical coordinate system may even be given a transformation by referring to a previously defined transfor mation If the R axis is normal to the element then the local y axis of the element will be parallel with the axis of the cylindrical spherical coordinate system No additional transformation of the cylindrical or spherical coordinate system is performed Name of a previously defined coordinate system Name of a previously defined transformation If local coordinate system of a surface 1s undefined the PROPERTY LOCAL COORDINATE SURFACE command has not been used then the GLOBAL option will take effect This command is irrelevant for all elements but the layered element SESAM Prefem Program version 7 1 01 JUN 2003 PROPERTY MATERIAL ANISOTROPIC CONTACT DAMPER MATERIAL material name ELASTIC MASS NON LINEAR ELASTO PLASTIC gt SPRING a This option is presently inactive b This option is presently inactive PURPOSE The command defines Material types to be connected to elements using the CONNECT command Stiffness matrices of spring elements to be referred t
385. tive b This option is presently inactive c This option is presently inactive PURPOSE The command sets parameters controlling the creation of the mesh especially corner types for surfaces See Section 3 4 4 for general information as well as examples of corner types SESAM Program version 7 1 PARAMETERS COORDINATE SYSTEM select geometry coord name CORNER TYPE surface name point name CORNER CUT CORNER LARGE CUT CORNER NOT CORNER SMALL CUT CORNER TRIANGULAR BOTH NONE TRIANGULAR BOTH ONE TRIANGULAR BOTH TWO TRIANGULAR ELEMENT TRIANGULAR POST NONE TRIANGULAR POST ONE TRIANGULAR POST TWO TRIANGULAR PRE NONE TRIANGULAR PRE ONE TRIANGULAR PRE TWO EDGE RECTANGULAR Prefem 01 JUN 2003 5 241 Set the coordinate system to use for creating the mesh This op tion allows the mesh to be created in a cylindrical or spherical coordinate system This has certain advantages for creating ir regular meshes as explained in see Section 3 4 5 Select appropriate geometry being bodies and or surfaces See Section 5 1 on how to perform a selection Name of a previously defined coordinate system Set a corner type for a surface Name of the surface Wild card name is not allowed Name of a point on the border of surface name The point will be a mesh corner See the note below The point will be a cut corner The point will be a large cut corner The point will be a not mesh corner The point will
386. to d o f number 1 of the relevant node This implies that a 0 involves full release of the d o f from the node 05 1 involves full fixation of the d o f to the node The result of the PROPERTY HINGE command may be printed by the PRINT ELEMENT select element HINGE command PARAMETERS select lines Select lines See Section 5 1 on how to perform a selection point One of the two end points of the selected line s Wild card se lection is allowed and must be used if more than one line has been selected If the wild card specification matches one of the end points of the selected line s then the hinge will be inserted If the wild card selection matches non of or both end points the hinge will not be inserted GLOBAL The hinge conditions refer to the cartesian coordinate system of the model Prefem 5 134 TRANSFORMED LOCAL COORDINATE SYSTEM LOCAL BEAM COORDINATE SYSTEM trnam coord name UNTRANSFORMED FIXATION alphai STIFFNESS ci INFINITY SESAM 01 JUN 2003 Program version 7 1 The hinge conditions refer to a previously defined transforma tion of the cartesian coordinate system see the command DE FINE TRANSFORMATION The hinge conditions refer to a previously defined cylindrical or spherical coordinate system see the command DEFINE COORDINATE SYSTEM The hinge conditions refer to the local coordinate system of the element itself Name of a previously defined transformation Name of a
387. trated by the right most sketch TAA line load as specified as interpreted alt 1 as interpreted alt 2 proper specification load 2 Figure 5 41 Incorrect and correct specification of line loads for membrane model Prefem SESAM 5 158 01 JUN 2003 Program version 7 1 PROPERTY LOAD load case LINE MOMENT LINE MOMENT select lines GLOBAL TRANSFORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam INSIDE SURFACE SHELL ELEMENT imx imy imz MIDDLE SURFACE SHELL ELEMENT OUTSIDE SURFACE SHELL ELEMENT BEAM ELEMENTS END MEMBRANE ELEMENT MIDDLE LAYER LAYERED ELEMENT layer PURPOSE The command defines line distributed moments acting on lines The line moment must be defined to be acting on either three node beam elements or shell elements If the moment is defined to be acting on say a beam element but only shell elements are present then no load will apply If e g both beam and shell elements are present then the moment may be applied to either of them For shell elements the moment is applied to the inside middle or outside surface of the elements For the concept of inside and outside of surfaces see Section 3 12 3 For layered elements the moment is applied to the middle layer of an identified layer number Alternatively to giving constant moment components varying moments may be specified by functions see Sectio
388. unction Prefem SESAM 5 18 01 JUN 2003 Program version 7 1 SIN COSIN SIN argument COSIN PURPOSE The command calculates sinus and cosine of the argument The argument is in radians Simple sinus and cosine functions are established by using the LINEAR 2POINTS VARYING function as argument This linear function is Prefem s way of establishing the argument x in the sinus and cosine functions sin x and cos x See the example below PARAMETERS argument Argument or function P2 PI Figure 5 14 Example of use of SIN function SESAM Prefem Program version 7 1 01 JUN 2003 5 19 EXP LN EXP LN argument PURPOSE EXP calculates the exponential function e LN calculates the natural logarithm In x An exponential function and a natural logarithm function are established by using the LINEAR 2POINTS VARYING function as argument See the explanation for the SIN COSIN functions for how to use the EXP and LN functions PARAMETERS argument Argument or function Prefem SESAM 5 20 01 JUN 2003 Program version 7 1 ABS SIGN MAX MIN DIM SQRT ABS SIGN MAX argument MIN argument argument2 SQRT argument PURPOSE ABS calculates the absolute value of the argument SIGN determines the sign of the argument as follows e SIGN a 1 ifa gt 0 e SIGN a lifa lt 0 e Ifa 0 or 0 then the functio
389. undamental equation is FORCE MASS ACCELERATION In terms of the fundamental units of mass M length L and time T this equation may be written F M L T Force stress density etc are not fundamental units and must be derived in terms of the fundamental units of M L and T The first step in determining a set of consistent units is to select fundamental units Input values to the pro grams such as steel density and Young s modulus input to Prefem and water density and gravity input to Wadam must then be determined in terms of these fundamental units Whenever possible it is simplest to use the SI units or multiples of the SI units length in metres m mass in kilograms kg time in seconds s A force will then be in Newton N 1IN 71kgm s B2 1 Example A model has been generated with centimetres cm as length unit We want our output force unit to be tonnes force tonnef and thus need to know which values for Young s modulus and steel density to specify in Prefem and which values for gravity and water density to specify in Wadam We first determine what our fundamental units of M L and T are L is in centimetres cm T is chosen to be in seconds s We have already chosen the force unit to be tonnes force tonnef and we know that 1 tonnef 9810 kg m s 10000 kg m s Insert this in the fundamental equation F M L 15 10000 kg m s M cm s 10000 kg 100 cm s 2 M cm s SESAM Prefem Pro
390. ure line loads temperature concentrated loads prescribed dis placements and prescribed accelerations can be specified as values varying in space Rather than giving a single numeric value for a load component a function describing its variation in space may be entered A function is defined based on a set of pre defined basic functions mathematical functions arithmetric opera tors and constants The various basic and mathematical functions are listed below and described in more detail later in this section The basic functions available are LINEAR 2POINTS VARYING see page 5 10 LINEAR 3POINTS VARY ING see page 5 11 SESAM Prefem Program version 7 1 01 JUN 2003 5 7 LINEAR RADIUS VARYING see page 5 12 CYLINDRICAL ANGLE VARY ING see page 5 13 CYLINDRICAL RADIUS VARYING see page 5 14 The function may be restricted to only having a value between two points 1 e zero value outside VALUE BETWEEN see page 5 15 The validity of the function may be restricted to only elements between two points i e undefined not the same as zero outside ONLY BETWEEN see page 5 17 In addition the following mathematical functions are available SIN see page 5 18 COSIN see page 5 18 ABS see page 5 20 SIGN see page 5 20 EXP see page 5 19 LN see page 5 19 DIM see page 5 20 SQRT see page 5 20 MAX see page 5 20 MIN see page 5 20 The constant n is entered by the parameter PI Parentheses may be used for building up expressions
391. urface must have been assigned the appropriate element type The layered element data must previously have been defined by the DEFINE LAYERED command A new CONNECT command for the same geometry will override previous assignments PARAMETERS LAYERED layered name select surfaces MATERIAL material name select geometry SECTION section name select lines Connect layered element data Previously defined layered name Surfaces for which the layered element data shall apply See Section 5 1 on how to perform a selection Connect material data Previously defined material name Geometry to which this material shall apply See Section 5 1 on how to perform a selection Connect cross sectional data Previously defined cross section name Lines for which the cross sectional data shall apply See Section 5 1 on how to per form a selection Prefem 5 48 COPY SESAM 01 JUN 2003 Program version 7 1 COPY select geometry mask trnam TRANSLATION VECTOR REPEAT n times dx dy dz PURPOSE The command copies geometry This may either be done by means of a geometrical transformation or through a translation defined by a vector The transformation must previously have been defined by the command DEFINE TRANSFORMATION The former method is the more general one as the transforma tion matrix may contain rotations mirroring and even scaling The latter met
392. urface specification must be entered but the data is irrele vant and is not used The HYDRO PRESSURE is used for two kinds of fluid pressures both to be computed in subsequent Wadam analyses e Hydrostatic and hydrodynamic pressures on the outside the hull of a floating object The identified sur faces the wet surfaces must extend at least up to the water line The exact position of the water line is determined by Wadam This load case number must be 1 Fluid pressures in tanks The identified surfaces the inside of tanks must extend up to the fluid level i e the surfaces identifies the level of the fluid The load case number must be 2 or higher This number is at the same time an identification of tank number which is referred to in the Wadam or rather Prewad input when defining tank properties The HYDRO PRESSURE load case s do not in themselves define any loading conditions When combin ing loads in Presel in connection with a superelement analysis and interpreting results from the hydrody namic and structural analyses these HYDRO PRESSURE load cases are irrelevant Prefem 5 154 PARAMETERS select surfaces INSIDE OUTSIDE INSIDE SURFACE OUTSIDE SURFACE MIDDLE SURFACE INSIDE LAYER MIDDLE LAYER OUTSIDE LAYER layer NOTES SESAM 01 JUN 2003 Program version 7 1 Select surfaces See Section 5 1 on how to perform a selection The inside is the wet surface The outside is the wet surface Pressure is
393. ween a selected geometry and a point e g for coupling the end of a tube modelled by shell elements to a beam element The boundary condition linear is automatically introduced for the dependent d o f when using either of the alternatives above When displaying the mesh and labelling node symbols these nodes will appear as blue triangles Note Ifthe dependent node or d o f already has a boundary condition e g fixed or super then it is changed to linearl However if the current boundary condition is prescribed or superl see below for this boundary condition code then the boundary condition is not changed rather a warning is given For the independent or governing d o f there are two alternatives e The independent d o f may automatically be given the boundary condition superl This is the default condition but if you want to set this mode then give the command SET DEFAULT LINEAR DEPEND ENCY MODE FORCE TO SUPER prior to the PROPERTY LINEAR DEPENDENCY command Superl is in effect the same as super the I merely indicates that the d o f is super because another d o f is linearly dependent of it Such a superl d o f may also be used as a normal super d o f for cou pling superelements Even if the FE model created comprises the whole structure the structure is not Prefem SESAM 3 52 01 JUN 2003 Program version 7 1 divided into several superelements Presel must be used to assemble t
394. with two decimals 0 12E 03 F FORMAT F format is selected Example with two decimals 123 00 NUMBER OF DECIMALS Set the number of decimals to use for numerical values Exam ple with three decimals and E format 0 123E 03 number of decimals The number of decimals Prefem SESAM 5 230 01 JUN 2003 Program version 7 1 SET GRAPHICS PRESENTATION BETWEEN NODES DRAWN ECCENTRIC LINE WIDTH line width scaling OUTLINE SECTION SECTION AS SOLID BEAM ELEMENT ON OFF SHOW ECCENTRICITY SIMPLE SECTION NUMERICAL SYMBOLIC ON OFF LAYERS LOCAL AXIS OUTLINE AREA LAYERED ELEMENTS OUTLINE SECTION SHELL ONLY SOLID AREA SOLID SECTION ARROW LOAD CONNECTED ARROWS NUMERICAL NORMAL SIMPLIFIED ELEMENT THICKNESS FILLED ELEMENTS PRESENTATION MIDNODE ELEMENTS PURPOSE The command chooses between various graphic presentation modes for labelling of element thicknesses displaying beam elements displaying loads etc PARAMETERS BEAM ELEMENT Select display mode for beam elements SESAM Program version 7 1 BETWEEN NODES DRAWN ECCENTRIC LINE WIDTH line width scaling OUTLINE SECTION SECTION AS SOLID SHOW ECCENTRICITY SIMPLE SECTION ELEMENT THICKNESS NUMERICAL Prefem 01 JUN 2003 5 231 Draw the beam elements as straight lines between the nodes Draw the beam elements as straight lines taking their ecc
395. wo points Arc Circular arc defined by two points and a centre point ntersecton Intersection curve between two shapes and going from one point to another a third point is required for picking the proper intersection segment Line curve Spline B spline curve defined by an arbitrary number of points 2 Straight line segments between an arbitrary number of points and with nodes in Node line E the points when a FE mesh is created Curve Curve made by the GENERATE command using cylindrical or spherical coordi nate system Surface Enclosed by an arbitrary number of lines arcs splines and node lines Body Enclosed by top and bottom surfaces and an arbitrary number of side surfaces Prefem SESAM 2 4 01 JUN 2003 Program version 7 1 2 3 FE Model Creation Having defined the geometry consisting of points lines and curves surfaces and bodies the following data must be defined to enable automatic creation of the FE model Data determining the element discretisation i e number and spacing of elements for lines and curves the number of elements is given when defining the lines curves but may be changed later Desired type s of element The FE model mesh is automatically created by the command MESH as illustrated in Figure 3 29 A mesh consists of elements joined together in nodes 2 4 Shapes Modelling Tools Shapes are tools in the form of surfaces for defining geometry and for projecting FE mesh onto In itself a sh
396. y Boundary conditions Loads Note By default types of element for the lines surfaces and bodies are not copied Copying element type may however be switched on by the SET DEFAULT COPY ELEMENT TYPE ON com mand Prefem SESAM 5 50 01 JUN 2003 Program version 7 1 Note Spring and damper elements defined for points are not copied EXAMPLES The examples below are given to illustrate how names of geometry created by the COPY command are composed The geometry names are based on the naming system of the GENERATE command as explained and exemplified in Section 3 3 7 T1 T2 etc are previously defined transformations Whether the COPY command refers to a transformation or the TRANSLATION VECTOR option is used is irrelevant for the naming of the new geometry The following command copies all geometric entities starting with A The names of the new geometric enti ties will be the same as those of the originals only replacing the A by a B For example the copy of body AB111 will be named BB111 the copy of surface AU123 will be named BU123 etc COPY A B T1 In the following command body AB123 with all its surfaces lines and points will be copied The names of the new geometric entities will be the same as those of the originals only replacing the A by a C COPY AB123 C T2 In the following command surface AU123 with all its lines and points will be copied The mask name implies that the copies shall have the same names as
397. y ipz implies that the load is real The pressure is applied to the inside of the surfaces The pressure is applied to the middle of the surfaces The pressure is applied to the outside of the surfaces The pressure is applied to the inside of the specified layer The pressure is applied to the middle of the specified layer The pressure is applied to the outside of the specified layer Layer number see Section 3 10 2 Prefem 5 150 SESAM 01 JUN 2003 Program version 7 1 PROPERTY LOAD load case CONCENTRATED CONCENTRATED _ select points GLOBAL TRANSFORMED trnam UNTRANSFORMED LOCAL COORDINATE SYSTEM coord name trnam ifx ify ifz imx imy imz fx Ify fz mx my mz END PURPOSE The command defines concentrated loads forces and moments in points This load differs from the BEAM CONCENTRATED alternative in that it can only be applied in geometry points Alternatively to giving concentrated loads of constant magnitude varying loads may be specified by func tions see Section 5 3 PARAMETERS select points GLOBAL TRANSFORMED LOCAL COORDINATE SYSTEM UNTRANSFORMED trnam coord name fx fy fz mx my mz ifx ify ifz imx imy imz Select points See Section 5 1 on how to perform a selection The load components refer to the model s cartesian coordinate system The load components refer to a previously defined transforma tion

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