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1. SEL CRS VASSAL SS PR Yt I oI SKY MTS ATS SL SENG HESS IRSA SSN BHT sk SISTERS HEISEI RSE PP ISAO EER SEM BSS CA See fa OT if SOS V M Ht Figure 3 Meshing by default Zone where elements are smaller because of the surface shape GID USER MANUAL 101 2 2 Assignment around points 1 Select Mesh gt Unstructured gt Assign size on points A window appears in which to enter the element size around the points to be chosen Enter 0 1 and click OK 2 Select the point indicated in Figure 4 Press ESC to indicate that the selection of points is finished 3 Select Mesh gt Generate Mesh 4 5 A window opens asking whether the previous mesh should be eliminated Click Yes GiD then asks you to enter the maximum element size Leave the default value unaltered and click OK ae r ZA S CO Z N Pr aa r l4 ty Se F Ma i lt t S ET ee SS SS anes a ZAN i An ee SPEER OA KISAAA IE SIM te eas i A W xX BIE SA 5 p afi moe a fixe Mh ine En a SS Figure 4 Geometry of the model The point Figure 5 The mesh with a concentration of around which the mesh will be concentrated elements around the point 6 A concentration of elements appears around t
2. neal BY ai WE WZ Figure 4 Generating a mesh on a volume using points 5 Now volume number one is meshed using only the generated nodes Instead of pressing the ESC key the center mouse button or the mouse wheel can also be used 116 METHODS FOR GENERATING THE MESH 2 3 Generating the mesh using quadrilaterals 1 Select Mesh gt Element type gt Quadrilateral Select surface number 10 2 Select Mesh gt Generate mesh 3 A window comes up asking whether the previous mesh should be eliminated Click Yes 4 Another window appears in which the maximum element size can be entered Leave the default value unaltered and click OK The result will be the mesh illustrated in Figure 5 COUPE ORY ae eS zs Sa NES WAY ER PES EAN PERY SY YV Figure 5 An unstructured mesh generated using quadrilaterals 5 The surface is meshed with quadrilaterals forming an unstructured mesh GID USER MANUAL 117 2 4 Generating a structured mesh surfaces 1 To mesh surfaces with a structured mesh select the option Mesh gt Structured gt Surfaces gt Assign Select surfaces 11 and 12 and press ESC A window appears in which to enter the number of divisions that the lines to be selected will have Enter 4 4 Select the lines defining the boundaries of the surfaces Press ESC 5 Another window appears in which to enter th
3. i j SS Figure 19 Zone in the mesh to zoom in 2 Select View gt Mode gt Geometry to visualize the geometry of the piece Figure 20 3 An image like that shown in Figure 21 appears There is a rectangular surface that does not fit within the boundaries of a rounded corner surface a hole in this case We will suppose that the problematic surface is planar This way it can be erased and recreated in order to fit the rounded corner boundary 174 IMPORTING FILES 4 Select Geometry Delete gt Surfaces Select the problematic surface and press ESC Select Geometry gt Delete gt Lines Select the lines forming the problematic surface and press ESC 5 Use the option Geometry gt Delete gt Points to erase the points that do not belong to any surface 6 With Geometry gt Create gt NURBS surface gt By contour create a new surface The result is shown in Figure 22 Figure 21 7 Visualize the mesh again using Mesh gt View mesh boundary and magnify the zone indicated in Figure 23 ey ee i 1 Figure 22 8 Select View gt Mode gt Geometry 9 In this example the situation involves a contour of four lines that does not correspond to any real surface of the piece These lines were too far apart to be collapsed Figure 24 In this case all the visible lines may be selected since the program will only eliminate those which do not have entities covering them that is those which belong to the problemat
4. jy a ani NYY NK a i y V D X Rs N i eT Pat se ST may L gt zasenn PA A lt 2 5 SoS ES iS D 7 A 7 SZ Fy wa 7 nase ZS a gt az EZ Sa Zs ZS LER E SLE K iN 225S i Ki i L ZS lt i s ESL W Vie NOSS WoS Gs ee ZS Oey ESS lt lt pa lt p Ze EX cA E i es DN ESS EEE A Z i Wie LSS Lf gt f ill Figure 13 Mesh using the RJump mesher assigning sizes by chordal error and forcing an entity to be meshed In this last example we have forced the mesher not to skip an entity but it may be interesting in some models to allow the mesher only to skip a few entities meshing almost all or them In this case a different surface mesher can be selected in the Preferences window One option is the RSurf mesher which meshes everything except the entities that you ask it to skip using the Mesh gt Mesh criteria gt Skip command Here because RJump is not selected no entity will be skipped automatically according to tangency with neighboring entities The next example shows how to work with this mesher 8 9 10 11 12 Select Mesh gt Reset mesh data to reset all mesh sizes introduced previously A window opens advising that all the mesh information is goin
5. GID USER MANUAL 195 Potentials Prescrits Node Tipus Valor Etiqueta Set Cond Point Weight nodes loop nodes OnlyInCond NodesNum OTIC Cir end This provides a rundown of all the nodes assigned the condition Point Weight with a list of their identifiers and the first weight field of the condition in each case loop nodes OnlylnCond executes a loop that will provide a rundown of only the nodes that have been assigned a condition cond 1 returns the number 1 field of a condition previously selected with the set cond command The field of the condition may also be selected using the name of the condition for example cond weight 196 DEFINING A PROBLEM TYPE cmas2d bas Coordinates Node X W x set elems all loop nodes SEOmMeac Vaos 5e714 56 xNodesNum NodesCoord 1 real NodesCoord 2 real end nodes Connectivities Element Node 1 Node 2 Node 3 Material loop elems APOrmMeac 5 aes PO ao Oates bes Oa ElemsNum ElemsConec ElemsMat end elems Begin Materials N Materials nmats Mat Density loop materials scCorcmac so el ode 56 xset var PROP1 real Operation MatProp Density real MatNum PROP1 end Point Condi bVons Set Cond Point Weight nodes set var NFIX ink CondNumeneirties ant Concentrate Weights xNFIX Potentials Prescrits Node Tipus Valor Etiqueta Set Cond Point Weight nodes xloop nodes OnlyInCond xNodesNum conci 1L end GID USER MANUA
6. 9 Rotate the figure until the following position is achieved Next we will create the upper face of the cube by copying from point 1 to point 5 the surface created previously To do this select the copy command Utilities gt Copy In the Copy window we define the translation vector with the first and second points in this case 0 0 0 and 0 0 10 Option Do extrude surfaces must be selected this option allows us to create the lateral surfaces of the cube GID USER MANUAL 37 i 8 6 x Copy Entities type Surfaces Y Transformation Translation First point Murr Be D o Y D o eo z D o Second point Duplicate entities Do extrude Surfaces ne Create contacts Maintain layers Multiple copies h Select Cancel Tg NOTE If we look at the Copy Window we can see an option called Duplicate entities By activating this option when the entities are copied in this case from point 1 to point 5 GiD would create a new point point 6 with the same coordinates as point 5 If the user does not choose option Duplicate entities point 6 will be merged with point 5 when the entities are copied By labeling the entities we could verify that only one point has been created 38 INITIATION TO GID Finishing the copy command for the surface we obtain the following surfaces Now we can generate the volume delimited by these surfaces To create the volume simply select the command
7. Figure 4 The line segment selected Figure 5 Result of the translation is the translation vector with copy Click Select to select the line segment that forms an angle of 60 degrees with the horizontal Press ESC to indicate that the selection has been made Choose Geometry Edit Intersection gt Line line Select the two inner lines Click Yes to confirm that there is an intersection and that therefore the shortest distance between the two entities is 0 The intersection between the two entities lines creates a point This point will be the tangential center Press ESC to indicate that the process of intersection between lines is finished CASE STUDY 2 Center of Tangency Figure 6 The auxiliary lines Tg NOTE The Undo option allows you to undo the operations most recently carried out If an error is made go to Utilities gt Undo a window appears where you can select all the options to be eliminated GID USER MANUAL 19 3 CREATING THE FIRST COMPONENT PART In this section the entire model except the T junction will be created The model to be created is composed of two pipes forming a 60 degree angle To start with the first pipe will be created This pipe will then be rotated to create the second pipe 3 1 Creating the profile 1 Select the ok layer and click on Layer To use From now on all entities created will belong to the ok layer 2 Choose the Line option located in Geometry gt Create gt Strai
8. layer Hiding it simplifies the space on the screen Choose Geometry gt Create gt Object Circle Enter 10 5 0 as the center point Enter a normal to the XY plane Positive Z and a radius of 1 5 From the Toolbox use the Delete gt Surfaces tool to delete the surface of the circle so that only the line is left This way the Geometry Edit Intersection gt Multiple Lines option may be used to intersect the circle circumference Select only the circle and the two straight lines that intersect it Choose Copy from the Utilities menu and make seven copies Multiple copies 7 rotating the circle 45 degrees Using the intersection options delete the auxiliary lines leaving only the valid lines thus obtaining the new profile of the hole The result is illustrated in Figure 42 Create the hole in the surface of the wheel using Geometry gt Edit gt Hole NURBS Surface the result is shown in Figure 43 f A E m e Figure 42 The new hole profile Figure 43 The surface of the new optimized design 70 CASE STUDY 1 6 3 Creating the volume of the new design Repeat the same process as in section 4 3 1 Inthe Copy window choose Translation and Surfaces Enter two points that define a translation of 10 units for example 0 0 10 and 0 0 0 Make sure that the Multiple Copies value is 1 2 Choose Do Extrude Volume in the Copy window 3 Click Select and select the surface of the wheel Press ESC Figure 44 The
9. Fs New TI Open Reads postprocess files Open multiple Pa Merge Reads postprocess files wit Import multiples meshes Export Save the current image lt gt Preprocess in the selected format Ee l l i Print to file age Setup Printing options oro P Send the image to the printer Closes GiD ius J Quit Reads mesh and results information from an ASCII file Ctrl n Ctrl o Import files NASTRAN mesh FEMAP file TECPLOT ASCII file b 3D Studio file Cut d Graph Export files H Ctrl q Changes user interface to the preprocess phase GID USER MANUAL 13 Utilities In the postprocess phase the Utilities command permits the user to obtain information about entities Opens a window to handle the visualization style and the sets Utilities Chooses the preferred ____ E options for project TA Preferences Ctrl l Several tools like ______ Lists project entities and properties macros calculator Tools T Copy Ctrl c Indicates on the screen the Opens the postprocess KILE location of entities copy window Nodes List Elements Gives information Id about useful general Signal With this option it s possible to data of the project aite add textual information to the model such as distances angles or coordinates Dimension d Identifies any node of the mesh being viewed showing Collapse nodes Create its lab
10. Tg NOTE To visualize the geometry of the model use View gt Mode gt Geometry To visualize the mesh use View gt Mode gt Mesh GID USER MANUAL 63 5 2 Generating the mesh with assignment of size around points 1 Enter view rotate angle 90 90 ESC in the command line This way we will have a side view Figure 33 Side view of the part 2 Choose Mesh gt Unstructured gt Assign sizes on points A window appears in which to enter the element size around the point to be selected Enter 0 7 3 Select only the points on the wheel profile Figure 34 One way of doing this is to select the entire part and then deselect the points that form the prism hole Press ESC to conclude the selection process Figure 34 The selected points of the wheel profile 4 Choose Mesh gt Generate mesh Another option equivalent to view rotate angle 90 90 is Rotate gt Plane XY located in the mouse menu 64 CASE STUDY 1 5 A window opens asking if the previous mesh should be eliminated Figure 35 Click Yes Another window appears in which the maximum element size should be entered Leave the default value unaltered Dialog window x The old mesh will be erased Continue OK Cancel Figure 35 6 A third window shows the meshing process Once it has finished click OK to visualize the resulting mesh Figure 36 Figure 36 Mesh with assignment of sizes around the points on the wheel profile 7 A greater concentration of
11. void calculate double v auxl aux2 aux3 int nl n2 n3 int mat double x CGi y CGi double x num 0 y num 0 The calculate function This is the function that calculates the center of mass Declaration of the local variables used in calculate for ielem 1 ielem lt Nelem ielem nl N 0 ielem 1 3 n2 N 1 ielem 1 3 n3 N 2 ielem 1 3 Calculating the volume volume is the area provided we are dealing with 3D surfaces v fabs x n1 y n2 x n2 y n3 x n3 y n1 x n1 y n3 x n2 y n1 daea al velba e The geometric center of the element is calculated x CGi y CGi sums are calculated mat imat ielem x numt rho mat v x CGi y numr rho nat nyA OGI den rho mat v Main loop of the calculating function The identifiers of the nodes of the present element are saved in n1 n2 n3 This loop makes a rundown of all the elements in the mesh The volume is calculated for each element Here the volume is the area provided we are dealing with 3D surfaces The volume calculations are stored in the v variable The geometric center of the element is calculated coinciding with the center of gravity and the coordinates are stored in the x Cgi and y Cgi variables 214 DEFINING A PROBLEM TYPE The numerator sums are calculated When the loop is finished the following sums are stored in the x num and y num variables x num gt Pan V on Nor elm
12. 2 Dy Fin V om Vem elm The denominator sum is calculated When the loop is finished the following sum is stored in the den variable den b P A elm point weights for icnd 1 icnd lt Ncnd icnd inod nodc icnd x numt wval icnd x inod y_num wval icnd y inod den wval icnd Then the calculations associated with point weights are run using a loop that makes a rundown of all the conditions The results are added to the x num y num and den variables as seen in the formulae a x num 2 Pan Vie X im gt MN etm N E AP V a Vem i gt m Bee elm i l The value of point weights is added to the variable den N Gen De P V am Z Ae elm t GID USER MANUAL 215 x CG x num den y CG y num den Finally the result of dividing the x num and y num variables by the den variable is stored in the x CG and y CG variables N Vege Keim gt m E i l elm x CG x num den gt x CGS i DP V om T Dm elm i N DV ox Yem T IG y_CG y_num den gt Tees re N 2P Vee t gt m elm i void output char filedat 80 FILE fp fptest float raiz double pot The output function The output function creates three files flavia dat flavia res and boh The project mesh is stored in the flavia dat file The mesh is a 2D surface The results to be visualized in GiD Post process are stored in the flavia res file It
13. 4 factor f 5 4629 fixed deformation Results will be drawn on this deformed model Apply Close Figure 49 The Mesh Deformation window 153 View Results amp Deformation View results Main Mesh Reference mesh Deform reference mesh Of Original C Deformed Use this color T Analysis E static Step f Position vector Result Displacements rm 4 factor f 5 4629 tiked deformation This is a snapshot of the madel Results will NOT be drawn over this representation Apply Close Figure 50 The yellow deformed geometry Body Bound versus the original geometry Boundaries 154 POSTPROCESSING A RATCHET WHEEL 4 Now the deformed geometry can be visualized For example in the View Results window select Contour Fill and NODAL V MISES then click Apply Figure 51 Visualizing the results of the deformed mesh colored 4 4 Cuts and divisions 1 In GiD Post process you can cut or divide the mesh to visualize the results within the interior of the part Begin the cutting process by choosing Do cuts gt Cut plane gt 3 points 2 Using the Join Ctrl a option in the Contextual menu located in the mouse menu select the three points indicated in 3 A Cut is made see Figure 54 To visualize it click Off V perfil in the Select amp Display Style Figure 53 ra LT Wain Foam el i a O lax TA p C Z N CY LA
14. Select the last two lines created and the vertical line segment coming down from the tangential center see Figure 12 Press ESC GID USER MANUAL 81 Figure 11 Selecting the lines to intersect 9 Choose Geometry gt Delete gt All Types This tool may also be found in the GiD Toolbox Select the lines and points beyond the vertical that passes through the tangential center Press ESC They will be deleted and the result should look like that shown in Figure 13 Figure 12 Profile of the pipe and the auxiliary lines CASE STUDY 2 3 2 Creating the volume by revolution oS Rotation of the profile will be carried out in two rotations of 180 degrees each This way the figure will be defined by a greater number of points From the Copy window select Lines and Rotation Enter an angle of 180 degrees and from the Do extrude menu select Surfaces The axis of rotation is that defined by the line that goes from point 0 0 to point 200 0 Enter these two points as the First Point and Second Point Be sure to enter 1 in Multiple Copies Click Select For an improved view when selecting the profile click Off the aux layer Press ESC when the selection is finished The result should be that illustrated in Figure 14 Figure 13 Result of the first step in the rotation 180 degrees Repeat the process this time entering an angle of 180 degrees To return to the side view elevation choose Rotate gt Plane XY Choose
15. _ Choose Geometry Edit Intersection gt Surface surface Select the outer surfaces of each pipe thus forming the intersection of the two surfaces selected Repeat the process to obtain the four lines of intersection Figure 25 Creating lines of intersection between the surfaces 89 900 CASE STUDY 2 4 4 Deleting surfaces and lines 1 Choose Geometry Delete gt Surfaces and select the small surfaces inside the first pipe Press ESC to conclude the process of selection 2 Choose Geometry gt Delete gt Lines Select the lines defining the end of the second pipe foreground that are still inside the first pipe background The result is shown in Figure 27 Figure 26 Final configuration after deleting surfaces and lines GID USER MANUAL 91 4 5 Closing the volume 1 The model now has three outlets The two farthest from the origin of coordinates must be closed The third will be connected to the rest of the piece when the T junction is imported 2 Choose Geometry gt Create gt NURBS Surface gt By contour and then select the lines defining the outlet in the foreground of Figure 28 Press ESC see Figure 28 Figure 27 Creating a NURBS surface to close the outlet in the foreground 3 Repeat the process for the other outlet to be closed 4 From the Files menu select Save to save the file Enter a name for the file and click Save CASE STUDY 2 5 IMPORTING THE T JUNCTION TO THE MAIN FILE The t
16. consult www compassis com 130 POSTPROCESSING A RATCHET WHEEL 1 1 Reading the initial file 1 From the Files menu choose the option Read Select the file named pieza gid and click Open The geometry in Figure 1 appears on the screen 2 Choose Render Flat from the mouse menu 3 Choose Rotate gt Trackball from the mouse menu This tool is also located in the GiD Toolbox Make a few changes to the perspective in order to get an idea of the geometry under study Figure 1 Contents of the pieza gid file 4 Return to the normal visualization by selecting Render gt Normal This mode is more comfortable to work with GID USER MANUAL 131 2 CREATING A SINGLE VOLUME When you carry out a stress test which involves the different volumes that define a structural solid Ramsolid requires these volumes to share the surfaces of interaction that is these surfaces must belong to both volumes Since the geometry of this study is formed by two volumes with separate surfaces the volumes must be connected To do this we will delete the existing volumes those of the axle and the wheel and create one new volume as a union of the two 2 1 Deleting volumes and surfaces 1 Choose Geometry gt Delete gt Volumes 2 Select the two volumes in the file Press ESC 3 Choose Geometry gt Delete gt Surfaces Select the surfaces shown in Figure 2 and Figure 3 and press ESC Paj iis A 1 y 7 vi Pi EPN i ma oe T
17. created in a new layer that we will name prism 4 1 Creating the prism layer and translating the octagon to this layer 1 2 3 In the Layers window type the name of the new layer and click New Select the prism layer and click Layer To use to choose it as the activated layer Choose Lines in the Sent To menu in the Layers window Select the lines that define the octagon Press ESC to conclude the selection Select the profile layer and click Off to deactivate it CA Figure 21 The lines that form the octagon GID USER MANUAL 57 4 2 Creating the volume of the prism 1 First copy the octagon a distance of 50 units relative to the surface of the wheel which is where the base of the prism will be located In the Copy window choose Translation and Lines Since we want to translate 50 units enter two points that define the vector of this translation for example 0 0 0 and 0 0 50 Make sure that the Multiple Copies value is 1 since last time the window was used its value was 9 2 Choose Select and select the lines of the octagon Press ESC to conclude the selection Figure 22 Selection of the lines that form the octagon 3 Since the Z axis is parallel to the user s line of vision the perspective must be changed to visualize the result To do this use the Rotate Trackball tool which is located in the GiD Toolbox and in the mouse menu Figure 23 Copying the octagon and changing the pe
18. ielem fprintf fp 6d 6d 6d 6d 6d n ielem N O ielem 1 3 N 1 ielem 1 3 N 2 ielem 1 3 imat ielem fclose fp Creating the flavia dat file The flavia dat file contains information about a 2D surface The flavia dat file has a particular format which must remain intact if GiD is to read it The format of this file is the following e There are 6 header lines for entering general information about the project For this example enter the following information FILE project name CMAS Program for calculating the center of mass CIMNE 2000 G Rienzi GID USER MANUAL 217 e Then enter the number of elements and nodes in the mesh using the following format Number of elements Nelem number of nodes Nnod element type 3 A type 3 element means it is a three node triangle The next line is for general information For this example enter the following text NODES e Then list the coordinates of all the nodes using the following format Node identifier inod x coordinate x inod y coordinate y inod e The next line is for general information For this example enter the following text CONECTIVITIES e Toconclude list the connectivities between nodes For each element list these variables Element identifier ielem 1 node N 0 ielem 1 3 2 node N 1 ielem 1 3 3 node N 2 ielem 1 3 material imat ielem writing flavia res strcpy filedat pr
19. 2 A window comes up in which to enter the maximum element size of the mesh to be generated Figure 28 Leave the default value given by GiD unaltered and click OK Enter value window X Enter size of elements to be generated Figure 28 The window in which the maximum element size is entered 3 A window appears showing how the meshing is progressing Once the process is finished another window opens with information about the mesh that has been generated Figure 29 Click OK to visualize the resulting mesh Figure 30 GID USER MANUAL 61 Dialog window xj 7 Mesh Generated Press OK to see it Mum of Tetrahedra elements 3 18 Mum of nodes 1395 Figure 29 The window with information Figure 30 The mesh generated with about the mesh generated default settings 4 Use the Mesh gt View mesh boundary option to see only the contour of the volumes meshed without the interiors Figure 31 This visualization mode may be combined with the various rendering methods YY Re Arter bi ERRIA ae 1 i Y ex a H 4 j X PAALA SR F re UD Figure 31 Mesh visualized with the Mesh gt View mesh boundary option 62 CASE STUDY 1 5 Visualize the mesh generated with the various rendering options in the Render menu located in the mouse menu Figure 32 Mesh visualized with Mesh gt View mesh boundary combined with Render gt Flat 6 Choose View gt Mode gt Geometry to return to the normal visualization
20. ESC Figure 7 Visualization of the new volume 6 Choose Geometry gt Delete gt Lines and select all the lines in the model Press ESC 7 Only the lines not contained by the volume will be deleted 134 POSTPROCESSING A RATCHET WHEEL 3 CALCULATING WITH RAMSOLID Since this is a 3D problem the calculating module Ramsolid 5 5 will be used to run it First we must load the problem type ramsolid which is located in Data gt Problem type Note Your Ramsolid version can be different to the related 5 5 but the steps to follow will be analogous The object of the study is a ratchet wheel that permits rotation of the axle in only one direction The aim is to study how the part behaves when subjected to external forces especially when the wheel is in equilibrium In this condition rotation is blocked by the pole which resists the rotating force coming from the axle At the same time the pole exerts an equal and opposite force on one of the teeth This system is illustrated in Figure 8 Figure 8 Ratchet wheel and in red pole In order to simulate this condition the following simplification will be made the ends of the axle will be blocked and pressure will be applied to the surfaces of the tooth where the pole resists rotation The material is steel GID USER MANUAL 135 3 1 Defining the problem materials and conditions 1 Since this is a three dimensional solid problem choose the option Data gt Problem type gt RamSe
21. F a a oe _ j j T ee Y ie Y p Figure 2 The axle surfaces to select Figure 3 The wheel surfaces to select This option may also be found in the GiD Toolbox i Pressing the ESC key is equivalent to clicking the center mouse button t To facilitate the selection of these surfaces deactivate any unnecessary layers 132 POSTPROCESSING A RATCHET WHEEL Figure 4 The result after deleting volumes and surfaces 2 2 Creating new surfaces and the final volume 1 Choose the option Utilities gt Copy the Copy window appears In this window choose Translation and Lines The translation vector of the required translation is the line segment shown in Figure 5 Enter as First Point and Second Point the two points defining this vector These points are also shown in Figure 5 Figure 5 The translation vector and the points that define it GID USER MANUAL 133 2 Choose the option Surfaces from the Do Extrude menu in the Copy window 3 Verify that the Duplicate entities option is unchecked and then click Select and select the lines defining the hole in the wheel Press ESC See Figure 6 Figure 6 Visualization of the new surfaces created at one end of the axle 4 Repeat the process to create the surfaces at the other end of the axle 5 When all the surfaces have been created thus defining a new part axle and wheel as one choose Geometry gt Create gt Volume gt By contour and select all the surfaces Press
22. GiD GID USER MANUAL Ja NOTE One of the operations in the importing process is collapsing the model Figure 3 We say that two entities collapse when the distance between them being less than the Import Tolerance they become one The Import Tolerance value may be modified by going to the Utilities menu opening Preferences and bringing up the Exchange card By default the Automatic import tolerance value is selected With this option selected GiD computes an appropriate value for the Import Tolerance based on the size of the geometry Collapsing the model may also be done manually This option Is found In Geometry Edit gt Collapse gt Model 163 Preferences x 42raphical Meshing Exchange Font Impot M Automatic collapse after import i Automatic import tolerance value Import tolerance 0 0086035 Collapse amp Ignoring layers C Each layer separately M IGES Curve on surface from 30 Expat IF IGES B Rep output style Accept Reset Clase Figure 5 The Preferences window 164 IMPORTING FILES 2 CORRECTING ERRORS IN THE IMPORTED GEOMETRY The great diversity of versions formats and programs frequently results in differences errors between the original and the imported geometry With GiD these differences might give rise to imperfect meshes or prevent meshing altogether In this section we will see how to detect errors in the imported geometry and how to correc
23. GiD Post process Preprocess Postprocess D SOLVER D INPUT OUTPUT FILE FILE 186 DEFINING A PROBLEM TYPE GiD must adapt these data to deal with them Materials boundary and or load conditions and problem data in general must be defined GiD configuration is accomplished through text formatted files The following files are required a prb configuration of the general parameter mat configuration of materials and their properties cnd configuration of the conditions imposed on the calculation b bas template file the file for configuring the format of the interchange that mediates between GiD data and the calculating module The file for interchanging the data exported by GiD has the extension dat This file stores the geometric and physical data of the problem c bat the file that can be executed in batches called from GiD This file initiates the calculating module The calculating module in this example cmas2d exe solves the equations in the problem and saves the results in the results file This module may be programmed in the language of your choice GiD Post process reads the following files generated by the calculating module a project_name flavia res results file Each element of the mesh corresponds to a value b project_name flavia msh file containing the post process 2D mesh If this file does not exist GiD uses the preprocess mesh in the postprocess GID USER MANUAL 187 Diagram depic
24. Meshing gt Symmetrical structured triangles option is set If this option is not set the mesh presented in Figure 7 is produced with fewer nodes than if using the previous option Figure 7 Structured mesh of quadrilateral and triangular elements on surfaces with the option Symmetrical structured triangles not set GID USER MANUAL 119 2 5 Generating structured meshes volumes 1 To mesh volumes with a structured mesh select the option Mesh gt Structured gt Volumes 2 Select volumes 1 and 2 and press ESC 3 A window appears in which to enter the number of divisions that the lines to be selected will have Enter 6 4 Select lines of both volumes parallel to the X and Z axes GiD automatically selects all the lines in each volume parallel to these in order to create the structured mesh Press ESC 5 Another window appears in which to enter the number of divisions on the lines Divide the lines parallel to the Y axis into 8 segments Enter 8 and click OK 6 Select an edge of volume 1 or 2 parallel to the Y axis and press ESC Again the line division window comes up Since we have already finished the assignments click Cancel Figure 8 Structured volume mesh of hexahedra and tetrahedra Only volumes that are topologically cubic can be meshed with a structured mesh 120 METHODS FOR GENERATING THE MESH For structured volumes GiD generates hexahedron
25. PROBLEM TYPE Mat Density loop materials format 41 13 5e xset var PROPI real Operation MatProp Density real MatNum PROPL end This provides a rundown of all the materials in the project and a list of the identifiers and densities for each one MatProp density real returns the value of the property density of the material in a real format Operation expression returns the result of an arithmetic expression This operation must be expressed in C Set var PROP1 real Operation MatProp Density real assigns the value returned by MatProp which is the value of the density of the material to the variable PROP1 a real variable PROP1 returns the value of the variable PROP1 MatNum returns the identifier of the present material Point conditions Set Cond Point Weight nodes xset var NFIX int CondNumEntities int Concentrate Weights ANFIX This provides the number of entities that have been assigned a particular condition Set Cond Point Weight nodes this command enables you to select the condition to work with from that moment on For the present example select the condition Point Weight CondNumeEntities int returns the number of entities that have been assigned a certain condition Set var NFIX int CondNumEntities int assigns the value returned by the command CondNumEntities to the NFIX variable an int variable NFIX returns the value of the NFIX variable
26. Render Flat from the mouse menu to visualize a more realistic version of the model Return to the normal visualization with Render gt Normal This option is more comfortable to work with GID USER MANUAL 83 Figure 14 The pipe with disks created by rotating the profile Tg NOTE To select the profile once the first rotation has been performed first select all the lines and then delete those that do not form the profile Use the option Rotate gt Trackball from the mouse menu to rotate the model and make the process of selection easier 3 3 Creating the union of the main pipes 1 Choose the Zoom gt in option from the mouse menu Magnify the right end of the model Make sure the aux layer is visible From the Copy window select Lines and Rotation Enter an angle of 120 degrees and from the Do extrude menu select Surfaces Since the rotation may be done in 2D choose the option Two Dimensions The center of the rotation is the tangential center CASE STUDY 2 Figure 15 The magnified right end of the model and the lines to be selected 4 Click Select and select the four lines that define the right end of the pipe see Figure 16 Press ESC when the selection is finished Figure 16 Result of the rotation GID USER MANUAL 85 3 4 Rotating the main pipe 1 From the Copy window select Surfaces and Rotation Enter an angle of 60 degrees Since the rotation may be done in 2D choose the Two Dimensions optio
27. The imported geometry may contain imperfections that must be corrected before generating the mesh For this study an IGES formatted geometry representing a stamping die is imported These steps are followed e Importing an IGES formatted file to GiD e Correcting errors in the imported geometry and generating the mesh e Generating a conformal mesh and a non conformal mesh GID USER MANUAL 161 1 IMPORTING AN IGES FILE GiD is designed to import a variety of file formats Among them are standard formats such as IGES DXF or VDA which are generated by most CAD programs GiD can also import meshes generated by other programs e g in NASTRAN or STL formats 1 Select Files gt Import gt IGES View Geometry Ukilities Data Mesh Calculate Help Es Her Ctrl Ctrl r Ta Open Ctrl o lt 4 Save Ctrl s Save ag Ctrl Ctrl s Export d DF 2 e Parasolid r ACIS Ai Print to file WDA Fagerimage setup Rhino ca Print Shapetile Recent files d NASTRAN mesh Siem Ch SIL mesh VAML mesh S30 Studio mesh GID mesh Surface mesh Batch file Ctrl b Insert GID geometry 2 Select the IGES formatted file base igs and click Open The file importing process is not always error free Sometimes the original file has incompatibilities with the format required by GiD These incompatibilities must be overcome manually This example deals with various solutions to the diffi
28. USER MANUAL 183 GiD PROBLEM TYPE AN EXAMPLE DEFINING A PROBLEM TYPE This chapter takes you through the steps involved in defining a problem type using GiD A problem type is a set of files configured by GiD so that the program can prepare data to be analyzed A simple example has been chosen which takes us through all the associated configuration files while using few lines of code Particular emphasis is given to the calculation of the centers of mass for two dimensional surfaces a simple formulation both conceptually and numerically The tutorial is composed of the following steps e Starting the problem e Creating the materials definition file e Creating the general configurations file e Creating the conditions definition file e Creating the data format file e Creating the calculating program file and the execution files e Executing the calculating module and visualizing the results using GiD By the end of the example you should be able to create a calculating module that will interpret the mesh generated in GiD Preprocess The module will calculate values for each element of the mesh and store the values in a file in such a way as they can be read by GiD Post process 184 DEFINING A PROBLEM TYPE 1 INTRODUCTION Our aim is to solve a problem that involves calculating the center of gravity center of mass of a 2D object To do this we need to develop a calculating module that can interact with GiD 1 1 The pro
29. an Normal Show numbering of the 4 Quit Flat entities for preprocess as Smooth well for postprocess e Copies the drawing image shown on the screen to the clipboard closes GiD z i Activates or de activates the utr layers which form the project Ious and changes entities from send d one layer to another layer window 22 PRESENTATION OF GID 4 COMMAND LINE The Command Line option allows the user to directly enter all executable GiD commands without accessing the commands through drop down menus Enter commands This ig the PROFESSIONAL Version x 0 01258 p 0 01258 z 0 Command These commands should be written following the order which GiD would use to define them according to the Right buttons menus A side comment in reference to the Command Line GiD does not distinguish between the use of capital and small letters In addition in cases where ambiguities do not exist commands need not be written in entire words but can be written with the primary characters of each word 23 GID USER MANUAL INITIATION TO GID With this example the user is introduced to the basic tools for the creation of geometric entities and mesh generation 24 INITIATION TO GID FIRST STEPS Before presenting all the possibilities that GiD offers we will present a simple example that will introduce and familiarize the user with the GiD program The example will develop a finite element problem
30. be either positive or negative depending on whether the user wants to concentrate elements at the beginning or end of the lines Next a vector appears which defines the start and end of the line and which helps the user assign the weight correctly Select the top line and assign a weight of 0 5 to the end of the line Concentrate elements xX Start Weight loo Ok i Cancel Select the bottom line and assign a weight of 0 5 to the beginning of the line Concentrate elements R Stark Weight End Weight h a 0 5 0 0 Ok Cancel GID USER MANUAL From these operations we obtain the following mesh We can see that in the figure above the elements are concentrated in the left zone of the square 35 36 INITIATION TO GID 3 CREATION AND MESHING OF A VOLUME We will now present a study of entities of volume To illustrate this a cube and a volume mesh will be generated Without leaving the project save the work done up to now by choosing Files gt Save and return to the geometry last created by choosing Geometry gt View geometry In order to create a volume from the existing geometry firstly we must create a point that will define the height of the cube This will be point 5 with coordinates 0 0 10 superimposed on point 1 To view the new point we must rotate the figure by selecting from the Mouse Menu Rotate gt Trackball This option is also available in the toolbar
31. ce GID USER MANUAL 97 1 INTRODUCTION In order to carry out this example start by opening the project ToMesh4 gid This project contains a geometry that will be meshed using four different methods each one resulting in a different density of elements in certain zones 1 1 Reading the initial project In the Files menu select Read Select the project ToMesh4 gid and click Open The geometry appears on the screen It is a set of surfaces Select Render gt Flat from the mouse menu Select Rotate gt Trackball from the mouse menu This tool is also available within the GiD Toolbox Make several changes in the perspective so as to get a good idea of the geometry of the object 5 Finally return to the normal visualization selecting Render gt Normal This mode is more user friendly sia i toe b E Figure 1 Contents of the project ToMesh4 gid 1 The mouse menu appears when the right mouse button is clicked 98 ASSIGNING ELEMENT SIZES GID USER MANUAL 99 2 ELEMENT SIZE ASSIGNMENT METHODS GiD automatically corrects element sizes according to the shape of the entity to be meshed and its Surrounding entities This default option may be deactivated and reactivated by going to the Mesh menu selecting Preferences and then Automatic correct sizes Sometimes however this type of correction is not sufficient and it is necessary to indicate where on the mesh greater accuracy is
32. interval With this option it s possible to Create add textual information to the model such as distances i angles or coordinates Checks the internal coherence of the data base Delete Showbox 8 PRESENTATION OF GID Data This menu allows access to the definition of all data related to materials boundary conditions etc which will be necessary for the calculations that follow The form of this data will depend on the type of the analysis to be performed Defines type of problem calculation Describes the properties of E ansye55 the problem and other data emas2d related to the geometric Problern type E p entities _ sampes Santee ramgenes5 5 Describes materials a used in the problem Materials Transform Interval Data Interet Retrieve o le Problem Data Load Defines general Data units Unload Debugger data of the interval Interval l Local ares Describes generally the problem data Divides information of problem into intervals Defines the units used in the problem New Changes and defines local Current coordinate axes Delete Define Draw Draw all Delete Delete all GID USER MANUAL 9 Mesh Mesh permits the user to generate and edit the mesh as well as to select mesh creation preferences Assigns element sizes Defines a structured to entities for non mesh structured mesh Sa Lines i mi Surfaces F Gy Volumes Unstructured j ASs
33. is using the Coordinates Window found in Utilities gt Tools gt Coordinates Window Pressing the ESC key is equivalent to pressing the center mouse button 46 CASE STUDY 1 2 2 Dividing the auxiliary line near point coordinates 40 0 1 Choose Geometry gt Edit gt Divide gt Lines gt NearPoint This option will divide the line at the point element on the line closest to the coordinates entered 2 Enter the coordinates of the point that will divide the line In this example the coordinates are 40 0 On dividing the line a new point entity has been created 3 Select the line that is to be divided by clicking on it 4 Press ESC to indicate that the process of dividing the line is finished Figure 3 Division of the straight line near point coordinates 40 0 2 3 Creating a 3 8 radius circle around point 40 0 1 Choose the option Geometry gt Create gt Object gt Circle 2 The center of the circle 40 0 is a point that already exists To select it go to Contextual gt Join Ctrl a in the mouse menu right click The pointer will become a square which means that you may click an existing point 3 The Enter Normal window appears Set the normal as Positive Z and press OK 4 Enter the radius of the circle The radius is 3 8 Two circumferences are visualized the inner circumference represents the surface of the circle 5 Press ESC to indicate that the process of creating the circle is f
34. loop end commands used to indicate the beginning and the end of the loop The command loop receives a parameter loop nodes the loop iterates on nodes loop elems the loop iterates on elements loop materials the loop iterates on assigned materials set elems all the command to include all the elements of the mesh when making the loop format the command to define the exit format for numerical expressions This command must be followed by the numerical format expressed in C NodesNum returns the identifier of the present node NodesCoord returns the coordinates of the present node NodesCoord n real returns the x y or z coordinate in terms of the value n n 1 returns the x coordinate n 2 returns the y coordinate n 3 returns the z coordinate Connectivities Element Node 1 Node 2 Node 3 Material loop elems format 91015 1004 tOr 1 01 9 1 04 ElemsNum ElemsConec ElemsMat end elems This provides a rundown of all the elements of the mesh and a list of their identifiers the nodes that form them and their assigned material ElemsNum returns the identifier of the present element ElemsConec returns the nodes of an element in a counterclockwise order ElemsMat returns the number of the assigned material of the present element Begin Materials N Materials nmats This gives the total number of materials in the project nmats returns the total number of materials 194 DEFINING A
35. may be used with some calculating modules i e stamping a plate Using non conformal meshes significantly reduces the number of elements in the mesh This cuts down on computation time 1 Select View gt Mode gt Geometry 2 Select Geometry gt Edit gt Uncollapse gt Surfaces Select all the surfaces in the model Press ESC A sufficient number of lines is created so that no surface of the object shares lines with any contiguous surface 3 Select Mesh gt Generate Mesh When the mesh has been generated a window appears with information about the mesh Figure 31 The result is a non conformal mesh composed of far fewer elements than the meshes generated in the previous section about 5000 elements instead of the 20 000 needed to generate the conformal mesh Dialog window x E Mesh Generated Press OK to see it Num of Triangle elements 4286 Num of nodes 4066 sreeersccecerscescvescescoeses Cancel Denvecceerecsesersccosessnsond Figure 30 A window containing information about the generated mesh 4 Visualize the result using Mesh gt View mesh boundary Figure 31 The mesh visualized using Mesh gt View mesh boundary 180 IMPORTING FILES 3 4 Optimizing a non conformal mesh Ig NOTE By using Chordal Error the geometry may be discretized with great precision The chordal error is the distance between the elements generated by the meshing program and the profile of the real object Entering a sufficient
36. needed In these cases GiD offers various options and methods allowing sizes to be assigned to elements Five examples are shown to illustrate the default method and the four other methods 2 1 Assignment using default options 1 Select Mesh gt Generate Mesh 2 A window appears showing the maximum element size Leave this default size unaltered and click OK 3 A meshing process window opens Then another window appears with information about the mesh generated Click OK to visualize the mesh see Figure 2 Figure 2 Meshing by default The Preferences option can also be found in the Utilities menu Automatic correct sizes automatically executes the options Assign sizes gt By geometry and Assign sizes gt Correct sizes 100 ASSIGNING ELEMENT SIZES Note that in the zone highlighted in Figure 3 elements are smaller than in the rest of the model This is because of the shape of the surface placed there When all meshing preferences are set to their default levels as for this example the RFAST surface mesher is used In this way geometrical entities are meshed hierarchically first of all lines are meshed then the surfaces and finally the volumes The line elements size depends on the shape of surfaces as can be seen in this example Later on we will see an example using RJUMP mesher where element sizes are distributed differently
37. number of elements the total calculation time can be rather long The calculation process runs in the background You can continue working with GiD albeit at a slower pace 144 POSTPROCESSING A RATCHET WHEEL 4 POST PROCESSING THE PART Once the calculation has been run the post process study may begin GiD Post process enables you to visualize the results based on the analysis 4 1 Visualizing the results 1 Select Files gt Postprocess 2 From the Windows menu choose the View Results option By default no result is visualized when you enter the post processing component View Results amp Deformation Ed View results Main Mesh Reference mesh Wew Contour Fill Shep Analysis Estatic f Displacements m Reactions N Stresses Fa Von Misses Factor Apply Close 3 Select Contour Fill in the View combo box and Von Misses from the list of available results Figure 25 Visualization of the VON MISSES calculation GID USER MANUAL 145 4 The View menu and the Results menu may be combined in order to see the various calculations with each one of the visualization methods For example select Windows gt View style and Hidden Bound in the Style combo box Then in the View results window select Contour Lines from the View combo box and from the list of results select the Sx component of the Stresses result Click Apply Figure 26 Visualization of the X component of the NODAL STRESS
38. of volume number 3 there is only one direction in which it can possibly be structured i e in the direction of the prism If the volume is prismatic in more than one direction there are two ways to choose between them selecting one top surface Mesh gt SemiStructured gt Set gt Master surface or the direction of the structure Mesh gt SemiStructured gt Set gt Structured direction The following example explains this procedure 13 Select the option Mesh gt SemiStructured gt Volumes 14 A window opens in which to enter the number of divisions in the structured direction prismatic Enter 6 15 Select volume 1 and press ESC 16 Select Mesh gt SemiStructured gt Set Structured direction GID USER MANUAL 123 17 Select one line parallel to the X axis of volume number 1 for example line number 11 and press ESC 18 Select Mesh gt Unstructured Assign Entities gt Surfaces 19 Select surfaces 1 and 6 and press ESC 20 Select Mesh gt Generate mesh 21 A window opens asking whether the previous mesh should be eliminated Click Yes 22 Another window appears in which to enter the maximum element size Leave the default value unaltered and click OK The result is the mesh shown in Figure 12 Figure 12 Semi structured volume mesh of prisms and hexahedra Tg NOTE As can be seen by selecting different element types for different geometrical entities several kinds of meshes can be generated Remember always to take care over
39. on both the geometry and the mesh entities Undo commands Chooses the preferred executed during the work options for project session Utilities D Undo Opens the layers window TA Preferences Ss Layers Moves entities as translation rotation Tools symmetry scale in this case without duplicating fF Copy entities Move Gives information about useful general data of the project E Statys _ T List Lists project entities and Renumber properties id pem Shows labels and coordinates of new or existing points A Distance l Dimension Indicates on the screen the location of entities Repair model Swap normals Manage the orientation of the entity normal Calculates the distance between points Ctrl z GiD is flexible in its configuration of the Ctrl p screen and accommodates different menus depending on the user s Ctrl l preference Toolbars Save window cont Cir deso Ctrl Coordinates window oe Read batch window Comments Animation controls b Animation script Macros Selection window Calculator ns Report Notes Copies all types of entities by b performing a translation rotation mirror symmetry or entity scaling Renumbers the entity labels in order to avoid gaps in numbering caused by the elimination of entities during the description of geometry and its properties Renumbers the mesh to decrease the analysis
40. permit the user to make choices related to the presentation of results for example color changes number of result subdivisions etc q Show Opaque Show Title ag Draw User Limits Border Change Title Outside ag Automatic Comments How volumes surfaces and cuts should be drawn Border Angle Massive Body Transparent Opaque Point options Line options Covering mesh Selects viewing options of iso areas Display Style j Render j Transparency d Convert to cuts Defines options for viewing graphics Outline on model Grids Current style Change style graph Change color graph Change line width Change line pattern Change pattern factor Change point size Change title graph Invert graph sense Delete graph Title Reset axis values 2 axis gt Y axis gt n a e a a a AUN a a e Clear grafs Selects box which shows the value scale of the results Legends Geometry Change Color Change Name Contour Iso Surfaces Vectors Stream Lines Graphs Line Diagrams Result Surface Elevations are lines that connect the nodes and the gauss points of the line element and the graph style line that represents the result Mone Show elevations Nodes only Whole line g Filled line Contour filled Changes color assigned to the volume surface and cut sets Volume sets Surface sels F Cut sets d Changes the name assigned to the volume
41. ten linear elements of two nodes To see the numbering of the nodes and mesh elements select from the Mouse Menu Label All and the numbering for the 10 elements and 11 nodes will be shown as below 11 3 3 4 4 amp fF F 7 amp A OF 9 If If 11 28 INITIATION TO GID Once the mesh has been generated the project should be saved To save the example select from the Top Menu Files gt Save The program automatically saves the file if it already has a name If it is the first time the file has been saved the user is asked to assign a name For this an Auxiliary Window will appear which permits the user to browse the computer disk drive and select the location in which to save the file Once the desired directory has been selected the name for the actual project can be entered in the space titled File Name Save Project l X Directory examples iJ C Import Particle gid E arc3Dgid D c1404 gid T cajon2D gid D cajon3D gid E frame gid ED motor gid E Te File name linitiatior Save Files of type GiD project gid Cancel Ja NOTE Next the manner in which GiD saves the information of a project will be explained GiD creates a directory with a name chosen by the user and whose file extension is gid GiD creates a set of files in this directory where all the information generated in the present example is saved All the files have the same name of the directory to which they belong but wi
42. the compatibility between element types in shared geometrical entities Volume number one have not been selected as semi structured but GiD will assign this mesh criteria to it automatically when selecting one of its lines to be a structured direction It s necessary to set one top surface of the volume unstructured because otherwise volume 1 will become totally structured It is because all contour surfaces of this volume have been assigned as structured automatically when assigning previously this kind of mesh to the volume step 2 of chapter 2 5 124 METHODS FOR GENERATING THE MESH 2 7 Concentrating elements and assigning sizes Select Mesh gt Structured gt Lines gt Concentrate elements 2 Select some structured lines for example lines 3 and 23 Press ESC 3 A window comes up in which to enter two values for the concentration of elements Positive values concentrate the elements and negative values spread them Enter 1 as Start Weight and 0 5 as End Weight Select Mesh gt Generate mesh A window opens asking whether the previous mesh should be eliminated Click Yes Another window appears in which to enter the maximum element size Leave the default value unaltered The result is the mesh shown in Figure 13 2 oS Figure 13 Concentration of elements on lines 3 and 23 It is also possible to assign sizes to geometrical entities so that mesh elements can be concentrated in certain zones In the follow
43. the element are saved in the first field The element identifiers are saved in the second All the elements are checked ensuring that they have been assigned a material If the identifier of the material is 0 meaning that no material has been assigned to the element an err file is created containing information about the error and the program is aborted 212 DEFINING A PROBLEM TYPE for i 0 i lt 5 i jumpline fp O fscanf fp ss ts d saul sau2 amp Nmat for i 0 i lt 3 i jumpline fp reading density of each material for i l 1 lt Nmat i fscanf fp 3d 1f amp aux amp rho i for i 0 i lt 4 i jumpline fp reading conditions fscanf fp 3d amp Ncnd for i 0 i lt 6 i jumpline fp for icnd 1 icnd lt Ncnd icnd fscanf fp od 1f amp nodc icnd amp wval icnd jumpline fp fclose fp Reading the remaining information in the dat file The total number of materials is read and stored in the Nmat variable The density of each material are read and stored in the rho table The material identifier indexes the densities The total number of conditions is read and stored in the Ncnd variable The nodes associated with a condition are read and stored in the nodc table indexed by the condition identifier The value of the condition is stored in wval another table indexed by the condition identifier GID USER MANUAL 213
44. to choose the viewing type in which the results of the postprocess calculation will be presented Results are not viewed View results __ No Results No Graphs Chooses which result to vie Default Analysis Step in colored iso areas Graphs are not viewed Contour Fill Chooses which result to view smooth Contour Fill in smoothed colored iso Contour Lines areas a Ranges Show Min blax Chooses which result to view in colored lines HUQ EM SEMI Iso Surfaces Shows outline of a particle by vector field as lines tangent to the result vectors Graphs Result Surface Graphs Deformation Line Diagram Stream Lines Clear Point evolution Point graph Border graph Line graph Draws a scalar result following the element Shows mesh deformation normal according to a displacement field Selects for which step of analysis results will be viewed Same as contour fill but with defined ranges ina Shows location and value of a selected maximum and minimum numerical result elects which vector result to view Creates iso areas of the results showing with colored strips the place where each subdivision finished Exact d Automatic j Automatic Width F T F F F F F FS F F Graph style lines will be drawn over the line elements only active when line elements are used in the mesh Scalar Vector F 16 Options PRESENTATION OF GID Options
45. value provided by GiD and click OK 12 The mesh generating process may be carried out with no further errors found Dialog window x i Mesh Generated Press OK to see it Mum of Triangle elements 11932 Mum of nodes b10 Figure 14 Window with information about the meshing process 13 The imported piece is now meshed Figure 16 Figure 15 A mesh of the imported geometry GID USER MANUAL 171 3 THE CONFORMAL MESH AND THE NON CONFORMAL MESH In the previous section after correcting some errors we were able to mesh the imported geometry thus obtaining a non conformal mesh A conformal mesh is one in which the elements share nodes and sides To achieve this condition contiguous surfaces of the piece must share lines and points of the mesh Most calculating modules require conformal meshes however some modules accept non conformal meshes A non conformal mesh normally requires less computation time since it generates fewer elements 3 1 Global collapse of the model 1 The option Mesh gt View mesh boundary shows the boundary of all the surfaces of the conformal elements 2 After generating the mesh select Mesh gt View mesh boundary This will result in the image pictured in Figure 17 1 i ae RE sd a a ee oes es j a aan Figure 16 Visualization of the boundary of the generated mesh 3 Visualization of the boundaries shows that in the interior of the piece some surfaces are isolated 4
46. will draw the octagon 1 Select from the menu Geometry gt Create gt Object gt Polygon to create a regular polygon Enter 8 as the number of sides of the polygon Enter 0 0 0 as the center of the polygon Enter or select 0 0 1 Positive Z as the normal of the polygon Enter 10 as the radius of the polygon and press ENTER Press ESC to finish the action ae a We get the result as shown in figure 20 As we only need the boundary we should remove the associated surface Select the option Geometry gt Delete gt Surfaces and then select the surface of the octagon Press ESC to finish Figure 17 Regular 8 sided polygon GID USER MANUAL 55 3 1 Creating a hole in the surface of the mechanical part 1 Choose the option Geometry gt Edit gt Hole NURBS Surface 2 Select the surface in which to make the hole Figure 18 3 Select the lines that define the hole Figure 19 and press ESC Figure 18 The selected surface in Figure 19 The selected lines that which to create the hole define the hole 4 Again press ESC to exit this function Figure 20 The model part with the hole in it 56 CASE STUDY 1 4 CREATING VOLUMES FROM SURFACES The mechanical part to be constructed is composed of two volumes the volume of the wheel defined by the profile and the volume of the axle which is a prism with an octagonal base that fits into the hole in the wheel Creating this prism will be the first step of this stage It will be
47. 2 The Preferences window 3 Select Mesh gt Unstructured gt Sizes by Chordal error and set the values as shown in Figure 34 Assign sizes by chordal error Figure 33 Defining unstructured size by chordal error 4 Select Mesh gt Generate Mesh 182 IMPORTING FILES A window comes up in which to enter the maximum element size Leave the default value unaltered and click OK 6 Once the process of generating the mesh is finished a window appears with information about the generated mesh Click OK to visualize the mesh p i X N WY INN ZN AY AA Ay Wee SK OPAC ae WES SPEAK IN a 7 WTB NES SS ay aN Se ROS BEETS RY NZ LIE XD ETS EA RA G WN A S N A EAN Ni TS V KS ZNI V vi V f era PE AA A p AARAA vy W a aN SS SA RY Se DARN LIN Lis 1 oe LAT X NN DS SY X UNS ip iy ye id id ih a X SAM abe aa LEK TIEN ANID SE Pa AVAL Hi R7 N av Is DAN t N NITIDIS Q 4 A BITATE A AUSTAN TATA WANA SAE PRA UY NAN A OE A S ARY a NEONY AR SALA lt p ma Py ma Ay iN ay Nn IN A NEA er wate E7 ye Ny K yj lt ij Fes PERV 15 Lg Vy i BX N NO Gy AKA et A iy N 9 LASS A SELLE SESERSESST ORE AN PTA va See KAA Je all a LA Ta Figure 34 An optimized non conformal mesh Structured elements are present on the curved surfaces GID
48. 7 Creating the Execution File for the Problem Type Create the cmas2d bat file This file connects the data file s dat to the calculating module the cmas2d exe program When the GiD Calculate option is selected it executes the bat file for the problem type selected When GiD executes the bat file it transfers three parameters in the following way parameter 3 bat parameter 2 parameter 1 parameter 1 project name parameter 2 project directory parameter 3 Problem type location directory Ja NOTE The bat file as used in Windows is explained below del 2 1 boh del 2 1 flavia res del 2 1 flavia dat This deletes results files from any previous calculations to avoid confusion rem OutputFile 2 1 boh A comment line such as rem OutputFile file name log means that the contents of the file indicated will be shown if the user clicks Output View in Calculate gt Calculate window Figure 4 In this example the boh file is shown This file contains the coordinates of the center of mass Process window Project Start time UID zi Output view Full Star remote Remate Close Figure 4 The Process window GID USER MANUAL 199 rem ErrorFile 2 1 err A comment line such as rem ErrorFile file name err means that the indicated file will contain the errors if any If the err file is present at the end of the execution a window comes up showing the error The absence
49. 99e 08 1 58876 08 9 59 07 3914 6 Figure 29 The color scale for the Figure 30 The color scale with the new limits default values for representing the VON MISSES calculation Contour Limits M Mex ie 009 M Min 55e 007 Figure 31 The Contour Limits window Figure 32 Entering the lower limit in the post process Toolbox 148 POSTPROCESSING A RATCHET WHEEL Figure 33 Visualization using the new color scale 8 The color scale is distributed between the values 1e9 and 5 5e7 All values outside this range are colored black The way in which these values are shown can be changed For example select these options Options gt Contour gt Min Options gt Out Min Color gt Min Color and Options gt Contour gt Max Options gt Out Max Color gt Transparent Those values below the visualization range are now represented in the same color as the minimum value Those values greater than the maximum value are not drawn they are perceived as transparent Figure 34 Visualization using the color scale established in step 8 The calculated values in transparent zones are greater than 1e9 GID USER MANUAL 149 9 10 Figure 35 Visualization of the results 11 View Results amp Deformation Ed View results Main Mesh Reference mesh Ve Display Vectors Shep Analysis E static l To return to the initial visualization Contour gt Reset Limit Values limit values choose Options gt Vi
50. A RATCHET WHEEL Select amp Display Style if Volumes I Surfaces Iw Cuts alphabetic order Massive options Transparent options Delete Style Body Lines Render Smooth Lal Culling None Conditions Geometry To back Send to Close Figure 48 The Massive and Transparent options in the Display Style window 4 3 Visualizing the deformed geometry 1 Choose Windows gt View results The View Results amp Deformation window appears 2 From the Style menu in the Select amp Display Style window select Boundaries 3 From the Mesh Deformation window select Deformation under the heading Main Geometry Under the heading Reference Geometry select Original Click Apply In order to better distinguish the two geometries select Body Bound from the Style menu in the Select amp Display Style window Ig NOTE Changes carried out in the Select amp Display Style window do not affect the reference geometry in Reference Geometry in the Mesh Deformation window Tg NOTE The factor box in the Mesh Deformation window indicates the multiplication factor of the real deformation Tg NOTE In the Steps boxes in the Mesh Deformation window the steps to be visualized can be selected GID USER MANUAL View Results amp Deformation EW View results Main Mesh Reference mesh Deform main mesh C Orginal Deformed Analysis E static Step Position vector Fest Displacements rn
51. FILE In our case the profile consists of various teeth Begin by drawing one of these teeth which will be copied later to obtain the entire profile 2 1 Creating a size 55 auxiliary line 1 Choose the Line option by going to Geometry gt Create gt Straight line or by going to the GiD Toolbox 2 Enter the coordinates of the beginning and end points of the auxiliary line For our example the coordinates are 0 0 and 55 0 respectively Besides creating a straight line this operation implies creating the end points of the line 3 Press ESC to indicate that the process of creating the line is finished 4 If the entire line does not appear on the screen use the Zoom Frame option which is located in the GiD Toolbox and in Zoom in the mouse menu Figure 2 Creating a straight line Ja NOTE The Undo option located in Utilities gt Undo enables you to undo the most recent operations When this option is selected a window appears in which all the operations to be undone can be selected 1 The GiD Toolbox is a window containing the icons for the most frequently executed operations For information on a particular tool click on the corresponding icon with the right mouse button The coordinates of a point may be entered on the command line either with a space or a comma between them If the Z coordinate is not entered it is considered O by default After entering the numbers press Return Another option for entering a point
52. Figure 6 12 Now go back and enter 0 6 in Unstructured Size Transitions This will result in a mesh more suitable for our objectives Click Accept GID USER MANUAL 2 3 Assignment around lines 103 1 Select Mesh gt Unstructured gt Assign size on lines In the window that appears enter the size of the elements around the lines that will be chosen Enter 0 5 and click OK 2 Select the lines defining the base of the prism i e lines 1 2 3 4 and 40 To see entity numbers select Label from the mouse menu or from the View menu If you wish geometrical entity labels to be displayed the view mode has to be set to Geometry using View gt Mode gt Geometry this option may also be found in the GiD Toolbox and the render mode must be set to Normal Press ESC Select Mesh gt Generate Mesh I at A window opens asking if the previous mesh should be eliminated Click Yes Another window appears in which you may enter a maximum element size Leave the default value unaltered and click OK This results in a high concentration of elements around the chosen lines given that the selected element size 0 5 is much smaller than that of the rest of the elements in the model See Figure 7 a gt NA Ny fat IN VE SO f D IA vo k A a AS KIRN WwW A A Z EA ies A lt i K i AT y E ian pa a fe TA Pe gt lt gt Figur
53. Geometry gt Create gt Volume gt By contour This option is also available in the toolbar w Select all the surfaces GiD automatically generates the volume of the cube The volume viewed on the screen is represented by a cube with an interior color of sky blue GID USER MANUAL 39 Before proceeding with the mesh generation of the volume we should eliminate the information of the structured mesh created previously for the surface Do this by selecting Mesh gt Reset mesh data and the following dialog box will appear on the screen Dialog window x DE i Cancel In which the user is asked to confirm the erasure of the mesh information Ja NOTE Another valid option would be to assign a size of 0 to all entities This would eliminate all the previous size information as well as the information for the mesh and the default options would become active Next generate the mesh of the volume by choosing Mesh gt Generate mesh Another Auxiliary Window appears into which the size of the volumetric element must be entered In this example the value is 1 lolx 7 Dialog window X Total number of surfaces i B Meshed surface E Mesh Generated Press OK to see it Hum of linear elementa 44 Total number of volumes Hum of Triangle elemens 103 Aum of Hexahedra elermnernt 9655 Hum of nodes 2114 Meshed volume 40 INITIATION TO GID The mesh generated above is composed of tetrahedral elements of four nod
54. GiD THE PERSONAL PRE AND POSTPROCESSOR The universal adaptive and user friendly pre and post processing system for computer analysis in science and engineering User Manual Version 8 Developers Ramon Ribo Miguel de Riera Pasenau Enrique Escolano Jorge Suit P rez Ronda Abel Coll Sans Cover design Lluis Font Gonzalez For further information please contact International Center for Numerical Methods in Engineering Edificio C1 Campus Norte UPC Gran Capitan s n 08034 Barcelona Spain http www gidhome com gid cimne upc edu Deposito legal B 34 736 02 ISBN User Manual 84 95999 94 3 ISBN Obra Completa 84 95999 96 x CIMNE Barcelona Spain TABLE OF CONTENTS PIreSeMlalOR OM GID aesa a a hentia oo aa r lee pone ad 1 TATION to GD cic 2 foes gat eawseticks e a a tia Coe ennnd eet EEn 23 Case study 1 implementing a mechanical Part cc ccc cece cece cena eee ee ee eeeeeeeeeaeeenaeees 42 Case study 2 implementing a cooling PIPE cece cece cece cece eee ee eee eeeeaeeeeaeeeeaeeeeaes 73 Assigning element sizes for generation the MESN cc ccc eee e cence cence eeeeeeeaeeeaeeeeaeees 96 Methods for generating the MESN cccc cece cece eee e eee e ee eee cease eee e eae eeaeeeaeeeaeeeaeeeaeenegs 111 A postprocess case study postprocessing a ratchet wheel c cece eeee eee eee eee eeees 128 IMADOFUING TIES a CaSe Std y viscera 8 ie pected oad oes te ae ee
55. Ign sizes on points io Assign sizes on lines i Assign sizes on surfaces in Assign sizes on volumes Hennes aeemi Structured j Sizes by chordal error structured mesh ee E Semistructured ES DY DACekQMound mEesM Volumes Corect sizes Quadratic elements k Sel j Assign entities Element type igg Describes element Mesh criteria j pma type to be used Chooses default mesh Reset mesh data criteria meshing of Tren w Normal l determined entities or Quadratic not of others Quadraticd A Generate mesh Deletes assigned Erase mesh Assign element information for mesh Srl meh b type to entities generation Show errors Default Linear j Draw in different View mesh boundary Triangle colors the different Create boundary mesh mse tered mesh information ee i Mesh quality Tetrahedra Herahedra Friem Generates the mesh Only points Shows boundaries Cancels previously of meshing Edits and permits generated mesh process changes to the mesh Move node Create _ Open the window with Shows quality of boundaries Split elements the last meshing error mesh elements of meshing Smooth elements message qenerated process Collapse Delete 10 PRESENTATION OF GID Calculate This command calculates the problem according to the type of problem defined This option requires a previously activated interface between GiD and the corresponding calculation program Start calculation proce
56. KI go VA Far N R is i CRN A R ES Lvl X AA KO LPNS ANEN A L NIA G be NZ ad Wy a Figure 52 The cutting plane defined by three points 1 Another option is Do cuts gt Cut plane gt 2 points Here the cutting plane is the plane perpendicular to the screen that passes through the line defined by the 2 points The cutting options are also located in the post process Toolbox GID USER MANUAL 155 Select amp Display Style i xj M Volumes M Surfaces M Cuts perfil CCutSet1 perfil e Color Rename Delete SEA Style Hidden Lines Render Normal Ss Culling None Conditions None Apply Close Figure 54 The section resulting Figure 53 V perfil is Off from the cut Tg NOTE The sections Cuts made in the original mesh also deform when the mesh deforms And vice versa the cuts made in the deformed mesh deform when the mesh returns to its original state 4 Starting from the View Results window select Contour Lines from the View menu and select Von Misses from the Results available in the list Click Apply thus visualizing the results within the cut Figure 55 Figure 55 Visualizing the results within the cut 156 POSTPROCESSING A RATCHET WHEEL 5 From the mouse menu choose Label gt Select gt Results Select several nodes thus ob
57. L LOr 1503 i lt 33 LaF jumpline fp reading density of each material for i l i lt Nmat recanti io Mics LOr 10 Nae Lar jumpline fp i aLliEY auk amp renoOlL reading conditions rscani ip s0 ENenel s BOr O O lie re Jumoline fp Lor Lenc l Lecnck Nenel ascend ie Cerin io Z jumpline fp relose E9 p void calculate double 77 raU slg WC ale Ay A int matp doubter COP y CGI glr amp naodelicnd ewval icnd s POP aor 7 couble x num 0 ena Ome ei Or for 1elem 1 ielem lt Nelem ielem nl N 0 ielem n2 N 1 ielem n3 N 2 ielem jew Calculating provided we Vi lige te foto awl Pavan Aa lac aaaletyaatoelac ol ator hori Molly oo Paidlt panel oho c pipe lins yal ialel e peel gee lies valleys ll yas The geometric center of the element is calculated x CGl x al tx y CG amp i y ai y Jj suns are calcul Ul E ieo T E the volume volume is the area are dealing with 3D surfaces ated 221 222 DEFINING A PROBLEM TYPE mat imat ielem x num te Oni iave lle Se Caz y num Sele ane es yry CGL den rho mat v OTa weergee 97 for rend gt 2end lt Nend LECNCH MAO nocdelicnel s x numr wyal icnel x inoe y num wyal icnc y inoe s den wval icnd x CG x num den y CG y_num den void output Chart ft le
58. L 197 2 6 Creating the Execution file of the Calculating Module 1 Create the file cmas2d c This file contains the code for the execution program of the calculating module This execution program reads the problem data provided by GiD calculates the coordinates of the center of mass of the object and the distance between each element and this point These results are saved in a text file with the extension flavia res 2 Compile and link the cmas2d c file in order to obtain the executable cmas2d exe file The calculating module cmas2d exe reads and generates the files described below READS the dat file This file stores the geometrie and physical data of the problem project name dat CREATES the flavia res file This file is the results file It contains the distance of each element relative to the center of masses of the project_mametlaviares object This file will be used by the GiD posiprocess CREATES the flavia dat file cmas d_exe This file contains the postprocess 2D mesh If this file does not exist GID uses the preprocess mesh in project_nameflavia dat the posiprocess CREATES the boh file The boh file contains the exact coordinates of the center of masses This file is not used by GiD project _name boh CREATES the err file This file is created only if an error occurs project _name err Ja NOTE The cmas2d c code is explained in the appendix 198 DEFINING A PROBLEM TYPE 2
59. RT THE T JUNCTION Now an intersection composed of two pipe sections will be created in a separate file and the surfaces will be trimmed Then this file will be imported to the original model to create the entire piece 4 1 Creating one of the pipe sections 1 Choose Files gt New thus starting work in a new file 2 Choose Geometry gt Create gt Point and enter points 0 9 and 0 11 Press ESC to conclude the creation of points 3 From the Copy window select Points and Rotation Enter an angle of 180 degrees and from the Do extrude menu select Lines The axis of rotation is the x axis Enter two points defining the axis one in First Point and the other in Second Point for example 0 0 0 and 100 O 0 Figure 22 4 Click Select and select the two points just created 5 Repeat the process this time entering an angle of 180 degrees thus creating the profile of the pipe section with a second rotation of 180 degrees The rotation could have been carried out in only one rotation of 360 degrees However in the present example each circumference must be defined between two points Figure 23 Figure 21 The result of the first Figure 22 The combined result of the 180 degree rotation first rotation and the second rotation of 180 degrees thus obtaining the profile of the pipe section 6 From the Copy window choose Lines and Translation In First Point and Second Point enter the points defining the translation vect
60. Select the profile layer in the Layers window The auxiliary lines will be eliminated and the profile layer will contain only the definitive lines 2 In the Sent To menu of the Layers window choose Lines in order to select the lines to be translated Select only the lines that form the profile Figure 14 To conclude the selection process press the ESC key or click Finish in the Layers window Figure 14 Lines to be selected 52 CASE STUDY 1 2 10 Deleting the aux layer 1 2 3 4 5 6 Click Off the profile layer Choose Geometry gt Delete gt All Types or use the GiD Toolbox Select all the lines and surfaces that appear on the screen The click and drag technique may be used to make the selection Press ESC to conclude the selection of elements to delete Select the aux layer in the Layers window and click Delete Select the profile layer Ja NOTE When a layer is clicked Off GiD reminds you of this From this moment on whatever is drawn does not appear on the screen since it is in the hidden layer NOTE To cancel the deletion of elements after they have been selected open the mouse menu go to Contextual and choose Clear Selection NOTE Elements forming part of higher level entities may not be deleted For example a point that defines a line may not be deleted NOTE A layer containing information may not be deleted First the contents must be deleted 2 11 Rot
61. Steel selected 3 Click Assign gt Surfaces and select the surface indicated in Figure 12 Press ESC when this step is finished pa Figure 12 Assigning the material Steel to the surface indicated 4 Choose the Mesh gt Generate option GID USER MANUAL 205 5 A window appears in which to enter the maximum element size for the mesh to be generated Enter 2 and click OK 6 Choose the Calculate option from the Calculate menu thus executing the calculating module 7 Choose the Files gt Postprocess option 8 Visualize the new results E Air L Steel Figure 13 Visualizing the materials Figure 14 Visualizing the distance MC making up the object DISTANCE from the center of mass of the object to each element for an object of heterogeneous material 9 As anticipated the center of mass is displaced toward the material with greater density 206 DEFINING A PROBLEM TYPE 3 3 Executing the calculation for an object of heterogeneous material and subject to external point weight 1 Choose the Files gt preprocess option 2 Choose the Data gt Conditions option A window is opened in which the conditions of the problem should be entered Figure 15 3 Since the condition to be entered acts over points select over points from the Type menu in the Conditions window Conditions Point weight amp weight Seg Assign Entities Draw Unassign Close Figure 15 The Conditions window 4 Enter the va
62. To generate a conformal mesh first execute a global collapse of the model 5 The GiD collapse depends upon the Import tolerance Two entities are collapsed converted into one when they are separated by a distance less than the Import tolerance parameter To test this enter a new value for the Import tolerance parameter 172 IMPORTING FILES Preferences x Graphical Meshing Exchange Font begg 0 Q AM i Automatic collapse after import i Automatic import tolerance value Import tolerance 0 0086035 Collapse amp Ignoring layers C Each layer separately W IGES Curve on surface from 30 Ex et IF IGES B Rep output style Accept Reset Close Figure 17 The Preferences window 6 Go to Utilities open Preferences and bring up the Exchange card Enter 0 15 for the Import tolerance value Click Accept 7 Select Geometry gt Edit gt Collapse gt Model 8 Select Mesh gt Generate and then visualize the results with Mesh gt View mesh boundary i f 7 Sa 4 SS Figure 18 The mesh after the collapse GID USER MANUAL 173 9 Some of the contiguous surfaces in the interior of the model have now being joined However there are still some surfaces that prevent the mesh from being completely conformal These surfaces must be modified manually 3 2 Correcting surfaces and creating a conformal mesh 1 With the option View gt ZoomJIn magnify the zone illustrated in Figure 20 cane ee
63. a window appears In the Units card make sure that Mesh units is set to m and that Results units is set to N m kg In the Gravity card we can change the direction in which gravity acts Leave this as the default value Z direction Press Accept Data to finish GID USER MANUAL vProblem data ed a E K Units Gravity Analysis Units Gravity Analysis Kesh units m Gravity amp D D Gravity V7 bo Results units N m kg l Gravity Z Hia Close Units Gravity Analysis Analysis Type Linear Static i Accept Close Figure 17 The Problem Data window 139 Tg NOTE GiD enables you to define intervals An interval is a set of conditions of the kind entered in this section Depending on the calculation mode intervals may be used for different reasons By default only one interval is used In the Data menu there is a submenu labeled Intervals where intervals can be managed New for creating a new interval Current for selecting the current interval and Delete for deleting the current interval 140 POSTPROCESSING A RATCHET WHEEL 3 2 Generating the mesh and running calculations 1 Choose Mesh gt Generate mesh 2 A window appears in which to enter the desired element size for the mesh to be generated Leave the default value provided by GiD unaltered and click OK When using an evaluation version this may cause a problem if the number of mesh elements generated exceeds the number permitt
64. aged in the materials window Figure 1 located in Data gt Materials cmas2d mat MATERIAL Air Materials QUESTION Density VALUE T Ol Air END MATERIAL Density i 01 MATERIAL Steel QUESTION Density VALUES 7850 END MATERIAL Draw Unassign Import Export MATERIAL Concrete QUESTION Density Close VALUES 2350 END MATERIAL Figure 1 The GiD Materials window for assigning materials DEFINING A PROBLEM TYPE 2 3 Creating the General File Create the cmas2d prb file This file contains general information for the calculating module such as the units system for the problem or the type of resolution algorithm chosen 2 Enter the parameters of the general conditions in cmas2d prb using the following format PROBLEM DATA QUESTION Name of the parameter If the name is followed by the CB instruction the parameter is a display type menu The options in the menu must then be entered between parentheses and separated by commas For example Unit System CB SI CGS User VALUE The default value of the parameter END GENERAL DATA 3 In GiD the information in the cmas2d prb file is managed in the materials window Figure 2 which is located in Data gt Problem Data Cmas2d prb Problem Data PROBLEM DATA QUESTION Unit System CB SI CGS User Unit System S VALUE SI QUESTION Title Title Default _title VALUE END GENERAL DATA Default title Figure 2 The GiD Problem Da
65. ate a point with the coordinates 40 8 5 Choose Geometry gt Create gt NURBS line to create a NURBS curve The NURBS line to be created will pass through the two first points which have been created on dividing the line at point 40 8 5 and by the two last points of the divided line Figure 40 Optimizing the design Select the first point through which the curve will pass To do this use Join Ctrl a located in Contextual in the mouse menu One at a time select the rest of the points except the last one Use Join Ctrl a each time in order to ensure that the line passes through the point Before selecting the last point choose Last Point in the Contextual menu Then finish the NURBS line The result is shown in Figure 40 Send the new profile See Figure 41 to the profile layer and eliminate the auxiliary lines Figure 41 Optimizing the design GID USER MANUAL 69 6 2 13 Repeat the process explained in sections 2 11 and 2 12 to create the wheel surface use the rotation tool to create the entire profile and using Geometry gt Create gt NURBS Surface gt By contour select it to create a NURBS surface 14 Repeat the processes explained in section 3 except section 3 1 and sections 4 1 and 4 2 to create the prismatic volume Modifying the profile of the hole a a Move the lines of the octagon placed in the profile surface to the profile layer with the Send To button Click Off the prism
66. ating and obtaining the final profile Make sure that the activated layer is the profile layer Use the option Layer To use In the Copy window select the line rotation Rotation Lines Enter an angle of 36 degrees Make sure that the center is point 0 0 0 and that you are working in two dimensions In the Multiple Copies box enter 9 This way 9 copies will be made thus obtaining the 10 teeth that form the profile of the model 9 copies and the original Click Select and select the profile Press the ESC key or click Finish in the Copy window in order to conclude the operation The result is shown in Figure 15 Figure 15 The part resulting from this process GID USER MANUAL 53 2 12 Creating a surface 1 Create a NURBS surface To do this select the option Geometry gt Create gt NURBS Surface gt By Contour This option can also be found in the GiD Toolbox 2 Select the lines that define the profile of the part and press ESC to create the surface 3 Press ESC again to exit the function The result is shown in Figure 16 CA Figure 16 Creating a surface starting from the contour Ja NOTE To create a surface there must be a set of lines that define a closed contour 54 CASE STUDY 1 3 CREATING A HOLE IN THE PART In the previous sections we drew the profile of the part and we created the surface In this section we will make a hole an octagon with a radius of 10 units in the surface of the part First we
67. blem center of mass The center of mass Xcu Ycm of a two dimensional body is defined as J cGy Gx Oy _ Jf es 9 9 Ox Oy f ox y Ox ay ff oxy axy Xcm where x y is the density of the material at point x y and S is the surface of the body If we consider the N gravitational forces as p g m each one concentrated on point x y the new center of mass will be modified as follows fle ee aed x flier aere my N Yom N o 20 dom o aav Xcu To solve the problem numerically the integrals will be transformed into sums N 2 DV in gt ee _ elm i l N gt Pon n l X elm E gt m i X _ elm i N gt PV ent 2 elm elm l elm i N 2 Pam V am oi 2 a i elm Xcu Yom Each of the N elements is treated as concentrated weight whose mass N is defined as the product of the surface density and the surface of the element GID USER MANUAL 185 1 2 Interaction of GiD with the calculating module GiD Preprocess makes a discretization of the object under study and generates a mesh of elements each one of which is assigned a material and some conditions This preprocessing information in GiD mesh materials and conditions enables the calculating module to generate results For the present example the calculating module will find the distance of each element relative to the center of mass of the object Finally the results generated by the calculating module will be read and visualized in
68. calculation using Contour Lines 146 POSTPROCESSING A RATCHET WHEEL Select amp Display Style Ed View Results amp Deformation Eg W Volumes W Surfaces I Cuts View results Main Mesh Reference mesh m SIE TESTE order Whew Contour Lines Step V perfi Analysis E static f Displacements rm Reactions M Stresses Pal E Rename EA a Su C F Delete a 5z a Ty Ste MEA 7 es Tsz Render Normal z w Si Stresses Fa Culling IN None Conditions None To back Send to Close Apply Close Figure 27 View Style window Figure 28 View Results window 5 Return to the visualization of the Von Misses calculation by using the Contour Fill option 6 The part will be rendered with a scale of colors covering the range of calculated values Figure 29 In this example only one interval of the total results range is of interest The scale of colors must be adapted so that the lower limit is 5 5e7 and the upper limit is 1e9 Figure 30 7 Choose Options gt Contour gt Define Limits The Contour Limits window appears Figure 31 Enter 1e9 in the box labelled Max and 5 5e7 as the Min value then click Apply This option is also available in the post process Toolbox Figure 31 GID USER MANUAL 147 Yon Misses VON MISES 1 42996 09 1e 09 1 271e 09 6 995e 08 141292 4 9e 06 e 04 a 6 89e 08 9 8e 08 TA 4 7499e 08 6 3557 08 3 6999e 06 4 7663e 09 2 6499e 08 3 17756 08 1 59
69. culties that may arise during the importing process 162 IMPORTING FILES Processing IGES X Collapsing X Directory Entry 6185 Mrnnnnnnnnnn EEETETETETDT Figure 1 Reading the file Figure 2 Collapsing the model Info window x IGES Global section parameters Sending System 981000p20 IGS File name 981000p20 1IGS System ID MATRA DATAVISION EUCLID3 Preprocessor Version IGES E32 1B00 Product ID 981000p20 1GS Model Scale 1 Unit flag Millimeters Date And Time Exchange 07 6 1999 17 19 0 Minimum Resolution 0 025 Approximate Maximum Coordinate 2500 Specification Version 5 1 Date And Time Modification 07 6 1999 17 19 0 Warning They are 1897 hidden entities in back layers Collapse geometry Time 4 seconds created 1773 points 1480 lines 4 surfaces 0 volumes Imp ortTolerance 0 011695 Error in NurbLine CalcCtlPlnSpline Interpolation points equal Error in NurbLine Createlnterpolated WARNING Line number 698 has bad definition and couldn t be fixed You should erase it Error in NurbLine CalcCtlPlnSpline Interpolation points equal Error in NurbLine Createlnterpolated WARNING Line number 839 has bad definition and couldn t be fixed You should erase it Figure 3 Importing process information 3 After the importing process the IGES file that GiD has imported appears on the screen al a x h il e x ik Figure 4 File base igs imported by
70. d conditions 192 DEFINING A PROBLEM TYPE 2 5 Creating the Data Format File Template file 1 Create the cmas2d bas file This file will define the format of the dat text file created by GID It will store the geometric and physical data of the problem The dat file will be the input to the calculating module Tg NOTE It is not necessary to have all the information registered in only one bas file Each bas file has a corresponding dat file Write the cmas2d bas file as follows 2 The format of the bas file is based on commands Text not preceded by an asterisk is reproduced exactly the same in the dat file created by GiD A text preceded by an asterisk is interpreted as a command Example bas file dat file Q 3 Problem Size Number of Elements amp Nodes nelem npoin The contents of the cmas2d bas file must be the following bas file Problem Size Number of Elements amp Nodes nelem npoin In this first part of the cmas2d bas file general information on the project is obtained nelem returns the total number of elements of the mesh npoin returns the total number of nodes of the mesh Coordinates Node X xset elems all loop nodes format S 51 914 5e 14 5e NodesNum NodesCoord l1 real NodesCoord 2 real end nodes GID USER MANUAL 193 This command provides a rundown of all the nodes of the mesh listing their identifiers and coordinates
71. daty E02 4 gt MN Sp VOLES double raiz double pot strcpy filedat projname streat irLledatc Do ir je fptest fopen filedat w Poti hie fprest FPILE s 8 A projname s rporinti Fprest YOMAS2D n2D routine to Calculate the mass center hekerogenens obj eck nduanuary 20 00 VeRmenz 1 Glanikrranco Ve ve Ve Ve CmMNE aa Point iprest ihe Mass Comects to lh i he miy ox CEs ye aa oe symeaiaie Tgiep pit beaut acer e 2 strcpy filedat projname Streaticr pt ledate ash lkanpiraycdeat jn fp fopen filedat w fod iis fo FILE so See projname s Pointe io VOMAS Va s forint fo Routine co calculare tche mass center of an object ya E E E ac E E TEENE a AA OOO RONA AN E EAEE NE A a ode ieee inn E E 5 OG 3 n Nelem Nnod EE Nao ie ClO ES Vienla ne For linoc il ned Nnied ined t fe ulalenvicde fo a OC 314 6e 514 6e n inoc x inod ylinoc s GID USER MANUAL 223
72. different entities As an example select Mesh gt Unstructured Size by chordal error GiD asks for the minimum element size Enter 0 1 GiD asks for the maximum element size Enter 10 Enter the chordal error This error is the maximum distance between the element generated and the real object Enter 0 05 and press OK Again select Mesh gt Generate Mesh A window opens asking if the previous mesh should be eliminated Click Yes Another window appears in which you can enter a maximum element size Leave the default value unaltered and click OK This results in a high concentration of elements in curved areas without the nodes in the lines and points that mesher skips Now our approximation is significantly improved see Figure 11 i 4 A 4 r Wee MAEA A aN Wise Te Fee SO Sa e EZO RES Sess Nie SI NES SSS WSS SS Ser WSS 2S eS SS OSS Ns ISS SS KN eS Nis Ma Mi ie W i N j N j cii ih Figure 11 Mesh using the RJump mesher and assigning sizes i i by chordal error 108 ASSIGNING ELEMENT SIZES 3 2 Force to mesh some entity If there is a line or a point that the RJump mesher would usually skip but that you wish to be meshed you can specify the entity so that it is not skipped As an example we will force Rjump to mesh line number 43 in order to concentrate elements around p
73. dow located in Utilities gt Copy 2 Repeat the rotation process explained in section 2 4 but this time with an angle of 36 degrees see Figure 6 Figure 6 Result of the rotations Tg NOTE The Move and Copy operations differ only in that Copy creates new entities while Move displaces entities GID USER MANUAL 49 2 6 Rotating and copying the auxiliary lines Use the Copy window located in Utilities gt Copy see Figure 9 2 Repeat the rotating and copying process from section 2 5 for the two auxiliary lines Select the option Lines from the Entities type menu and enter an angle of 36 degrees 3 Select the lines to copy and rotate Do this by clicking Select in the Copy window 4 Press ESC to indicate that the process of selecting lines is finished thus executing the task see Figure 7 Copy x Entities type Lines s Transtormation Rotation T Angle 36 Degrees First point Mum wi D D y D D a Z D D Figure 7 Result of copying and rotating the line A a Ine Second paint Mum w D D D D D D Rotate the line segment that goes from the origin to point 40 0 by 33 degrees and copy it see Figure 8 p o Duplicate entities Do extrude No T V Maintain layers Multiple copies Select Cancel Figure 8 Result of the rotations and copies Figure 9 The copy window Tg NOTE In the Copy and Move windows the option Pick may be used to select existi
74. e 7 Mesh with a concentration of elements around lines A yoy le sd ZA 2s SNS Kae es N hoe 5 Oe 4 104 2 4 Assignment on surfaces ASSIGNING ELEMENT SIZES 1 3 4 5 Select Mesh gt Unstructured gt Assign size on surfaces In the window that appears enter the size of the elements to be assigned on the surfaces that will be chosen Enter 0 5 and click OK 2 Select the triangular surface resulting from the section of one of the vertexes of the prism surface number 1 Press ESC Select Mesh gt Generate Mesh A window opens asking if the previous mesh should be eliminated Click Yes Another window appears in which you can enter the maximum element size Leave the default value unaltered and click OK This results in a high concentration of elements on the chosen surface due to the value selected 0 5 See Figure 8 ne V K RINEN WOA a T Se NO ETTA LORS ERTA aA S aA See ce SAA Weck Zt Weebly YO WIS Sc DSN WAIN SEIN WWAERNS 5 Ae Figure 8 Mesh with a concentration of elements on a surface GID USER MANUAL 105 2 5 Assignment with Maximum Chordal Error Select Mesh gt Unstructured Sizes by chordal error GiD asks for the minimum element size Enter 0 1 GiD asks for the maximum element size Enter 10 Enter the chordal error This error is the maximum distance between the element generated and the real object geometry Ent
75. e menu option Mesh gt Reset mesh data Tg NOTE On the Meshing card in the Preferences window there is an option labeled Unstructured size transitions which defines the transition gradient of element sizes size gradient the gradient values being between 0 and 1 the greater the size gradient the greater the change in space The default value for this element size is 0 6 1 Choose Mesh gt Unstructured gt Surfaces A window appears in which to enter the element size for the surfaces to be selected Enter size 1 2 Select the surfaces under pressure and the surfaces around them YL Figure 22 Selecting the surfaces to be assigned size 1 elements 3 Choose Mesh gt Generate mesh 4 A window appears asking whether the previous mesh should be eliminated Click Yes Another window opens in which the maximum element size should be entered Leave the default value unaltered GID USER MANUAL 143 Figure 23 Concentration of elements on the selected surfaces 5 Now the calculation can be run Choose the Calculate option from the Calculate menu 6 Wait until a window appears stating that the calculation is finished Process info I Process pleza_mallada started at Fri May 24 1a 45 32 has finished ae Figure 24 The Process info window Ig NOTE The greater the accuracy of the mesh the greater the accuracy of the calculation and representation in post processing Nevertheless bear in mind that for a large
76. e number of divisions on the lines In this case all the lines have already been defined with the same number of divisions Therefore click Cancel 6 Select Mesh gt Element type gt Triangle Select surface 12 w N Ja NOTE The edges of surfaces meshed with an unstructured quadrilateral mesh must always be divided into an even number of segments So if these surfaces share edges with a structured surface mesh the edges of the structured surface must also be divided into an even number of segments In this example therefore lines are divided into 4 segments by R TY LL ep BD BB OD oe a lt i D AOG h X Z lt Figure 6 Structured mesh of quadrilateral and triangular elements on surfaces When selecting a line GID automatically selects all lines parallel to it 118 CoN 10 METHODS FOR GENERATING THE MESH Select Mesh gt Generate mesh A window comes up asking whether the previous mesh should be eliminated Click Yes Another window appears in which to enter the maximum element size Leave the default value unaltered and click OK The result is the mesh shown in Figure 6 As seen in Figures 6 and 7 GiD can obtain surface structured meshes made of quadrilaterals or triangles There are two kinds of structured mesh that use triangles the one shown In Figure 6 is obtained when the Utilities gt Preferences gt
77. ed for unregistered copies of GiD tl This version of GiD only allows to Q generate 1010 nodes and there were 7570 Check menu Help gt Register GID 3 If you obtain a message like the one above you can get a temporary trial password or try generating fewer elements by changing the meshing preferences and selecting a larger element size a Select the option Mesh gt Reset mesh data to clear all previously assigned sizes b Open the Preferences window Utilities gt Preferences and select the Meshing card Set the value for Unstructured size transition to 0 9 click Accept and then Close c Select the option Mesh gt Generate mesh and set the size to 10 4 Once the meshing process has concluded a window appears with information about the mesh that has been generated Click OK to visualize it 5 Another window shows the meshing process When the process is finished use Mesh gt Vies mesh boundaries to see just the contours of the volumes that have been meshed not their interiors This visualization mode may be combined with one of the various rendering methods see Figure 18 wY UAN ot iT IS w Reker ER EES EA ETNEA E Sa EA PES E Poe rata wd a Se LORS A aa AT TAN a a s AZA Figure 18 Meshing the part with default settings GID USER MANUAL 141 6 Now we can begin to perform the calculations Choose the Calculate option from the Calculate menu The Ramsolid calculating m
78. el number and spatial F Deeg coordinates doin Ei Delete 5howBos Calculates distance Texture between two points To join several sets into one To delete meshes To collapse nodes those sets and cuts are together in a set To add textures ilps to sets Add Volume sets F Surface sets F Change Cut sets 14 Do cuts PRESENTATION OF GID With the option Do cuts the user can make cuts through entities Makes parallel sections defining an axis in the normal direction to the cuts and the number of divisions desired Do cuts along this axis og Cut Plane _ eee by selection Creates a set with the user Divide volume sets selection Divide surface sets Divide lines Makes section through a z plane This can be defined ut wire by two points and relative to Cut Sphere Makes a spherical cut the plane perpendicular to the screen or by three points Convert A zels With this options cuts can be converted to surface sets so they can be saved or cut again Divides volume sets in two parts cutting through two points and relative to the plane perpendicular to s the screen or by three d i Divides surface sets in two parts cutting through two points and relative to the plane perpendicular to the screen or by three points The user specifies a plane which is used to get the lines at one side of this plane GID USER MANUAL View results 15 This option permits the user
79. elements has been achieved around the points selected 8 Choose View gt Mode Geometry to return to the normal visualization GID USER MANUAL 65 5 3 Generating the mesh with assignment of size around lines 1 Open the Preferences window which is found in Utilities and select the Meshing card In this window there is an option called Unstructured Size Transitions which defines the size gradient of the elements A high gradient number means a greater concentration of elements on the wheel profile To do this select a gradient size of 0 8 Click Accept 2 Choose Mesh gt Reset mesh data to delete the previously assigned sizes from section Oc 3 Choose Mesh gt Unstructured gt Assign sizes on lines A window appears in which to enter the element size around the lines to be selected Enter size 0 7 Select only the lines of the wheel profile Figure 37 in the same way as in section 5 2 Figure 37 Selected lines of the wheel profile 4 Choose Mesh gt Generate mesh A window appears asking if the previous mesh should be eliminated Click Yes 5 Another window opens in which the maximum element size should be entered Leave the default value unaltered 66 CASE STUDY 1 6 A greater concentration of elements has been achieved around the selected lines In contrast to the case in section 5 2 this mesh is more accurate since lines define the profile much better than points do Figure 38 Figure 38 Mesh with assignment of sizes a
80. er 0 05 and press OK Select Mesh gt Generate Mesh A window opens asking if the previous mesh should be eliminated Click Yes Another window appears in which you can enter a maximum element size Leave the default value unaltered and click OK This results in a high concentration of elements in curved areas Now our approximation is significantly improved see Figure 9 a odd ees oe H AM FIIN Af ima TM y PS Aes XZ EAI ae a Mi i uy VA 3 n z i a N Wy i f NY Pa os ara e as gt 25 AN Si m i WA lt 2 NU I seca Oe T TA NS CIN Wiese gt OSS HS Wie SS SSS 7 aN ni es SE NNN SN 7S SSeS NINA lee ENNIS a an A VAN ONAA L NESS Zt SS W a W KIA j Aa 7 ee 7 lp aa e a EE Figure 9 Mesh using sizes assignment by chordal error Here there is a greater concentration of elements in the curved zones 106 ASSIGNING ELEMENT SIZES 3 RJUMP MESHER 3 1 RJump default options The RJump mesher is a surface mesher that meshes patches of surfaces in 3D space and is able to skip the inner lines of these patches when meshing By default the RJump mesher skips the contact lines between surfaces that are tangent enough and points between lines that are tangent e
81. es of the CENTER of MASSESS CREATES the boh file t contains ihe exact coordinates of the center of masses CREATES the flavia dat file This file comans the postoroacess 2D mesh CREATES the flavia res file t contains the distance of each element relative to the center of masses of the object Ig NOTE In this example a code for the program will be developed in C Nevertheless any language of choice may be used GID USER MANUAL 209 2 The code of the program that calculates the center of mass cmas2d c is as follows The cmas2d c file lt stdio h gt lt stdlib h gt lt fcntl h gt lt string h gt lt math h gt define MAXMAT 10000 define MAXCND 10000 char projname 1024 d4 int i ielem inod icnd double x y int N imat int nodc MAXCND double rho MAXMAT wval MAXCND int Nelem Nnod Nmat Ncnd double x CG y CG void input void void calculate void void output void Declaration of variables and constants used in the program void main int argc char argv void input void void calculate void void output void strcpy projname argv 1 input calculate output The main program The main program is called from the cmas2d bat file and has as its parameters the name of the project This name is stored in the projname variable The main program calls the input calculate and output function
82. es but GiD also permits the use of hexahedral eight nodded structured elements We will generate a structured mesh of the volume of the cube This is done by selecting Mesh gt Structured gt Volumes Now select the volume to mesh and enter the number of partitions in its edges which will be created Then create again the mesh xl T Mesh Generated Press OE to see it Enter value window Hum of linear elementa 44 Hum of Triangle element 104 Hum of Herahecdra elementa 1 000 Hum of nodes 1445 Cancel 41 GID USER MANUAL GiD only allows the generation of structured meshes of 6 sided volumes Il note With this example the user has been introduced to the basic tools for the creation of geometric entities and mesh generation 42 CASE STUDY 1 CASE STUDY 1 IMPLEMENTING A MECHANICAL PART The objective of this case study is implementing a mechanical part in order to study it through meshing analysis The development of the model consists of the following steps e Creating a profile of the part e Generating a volume defined by the profile e Generating the mesh for the part At the end of this case study you should be able to handle the 2D tools available in GiD as well as the options for generating meshes and visualizing the prototype GID USER MANUAL 43 1 WORKING BY LAYERS 1 1 Defining the layers A geometric representation is composed of four types of entities namely point
83. g to be erased Press OK Go to Utilities and open Preferences Click Meshing In the window that appears you can choose between the three surface meshers available in GiD RFast RSurf and RJump Select the RSurf mesher Click Accept Select Mesh gt Mesh criteria gt Skip gt lines and select lines 48 and 53 Press ESC Select Mesh gt Generate Mesh 110 ASSIGNING ELEMENT SIZES 13 A window opens asking if the previous mesh should be eliminated Click Yes 14 Another window appears in which you can enter a maximum element size Leave the default value unaltered and click OK The result is a mesh similar to the first example obtained in chapter 2 see Figure 2 but the smaller elements highlighted in Figure 3 do not appear because lines 48 and 53 which were meshed before are now skipped when meshing see Figure 14 aa Si A i mi Figure 14 Mesh using the RSurf mesher with some lines skipped GID USER MANUAL 111 METHODS FOR GENERATING THE MESH The objective of this example is to mesh a model using the various options available in GiD for controlling the element type in structured semi structured and unstructured meshes It also presents how to concentrate elements and control the distribution of mesh sizes The six methods covered are Generating a mesh using tetrahedra Generating a volume mesh using points Generating a mesh using quadrilaterals Generating a structured
84. ght line 3 Enter the following points 0 11 8 11 8 31 11 31 11 11 and 15 11 Press ESC to indicate that the process of creating lines is finished Figure 7 Profile of one of the disks around the pipe 4 From the Copy window choose Lines and Translation A translation defined by points 0 11 and 15 11 will be made In the Multiple copies option enter 8 the number of copies to be added to the original Select the lines that have just been drawn Figure 8 The profile of the disks using Multiple copies B00 CASE STUDY 2 5 Choose Line located in Geometry gt Create gt Straight line Select the last point on the profile at the right part of the profile using the option Join Ctrl a which is in the Contextual menu in the mouse menu Now choose the option No join Ctrl a Enter point 200 11 Press ESC to finish the process of creating lines 6 Again choose the Line option and enter points 0 9 and 200 9 Press ESC to conclude the process of creating lines Figure 10 Figure 9 Creating the lines of the profile Figure 10 Copy of the vertical line segment starting at the origin of coordinates 7 From the Copy window choose Lines and Translation As the first and second points of the translation enter the points indicated in Figure 11 Click Select and select the vertical line segment starting at the origin of coordinates Press ESC 8 Choose Geometry gt Edit Intersection gt Multiple lines
85. gn sizes on surfaces A window opens in which to enter the element size for the surfaces to be selected Enter size 1 Select the surfaces of the elbow Choose Mesh gt Generate mesh A window appears asking whether the previous mesh should be eliminated Click Yes Another window appears in which the maximum element size should be entered Leave the default value provided by GiD unaltered and click OK Choose Mesh gt View Mesh Boundary to see only the contour of the meshed volumes but not the interiors Figure 32 ane ks Figure 31 The mesh with a concentration of elements on the surfaces of the elbow 7 A greater concentration of elements has been achieved on the selected surfaces 96 ASSIGNING ELEMENT SIZES ASSIGNING ELEMENT SIZES FOR GENERATING THE MESH The objective of this example is to mesh a mechanical piece using the various options in GiD for assigning sizes to elements and the different surface meshers available In this example a mesh is generated for each of the following methods for assigning sizes using different surface meshers Assigning sizes around points Assigning sizes around lines Assigning sizes on surfaces Assigning sizes with Chordal Error OWN N i SO SSS f 4 SAK NXN IN W DOD NK NX Aas Nae EAX AN AO c7 a Dees KDB SES he lt i ZS L SZ BS rA A LO LNE P ab Lo PS See
86. he chosen point given the selected size 0 1 of these elements see Figure 5 T Go to Utilities and open Preferences Click Meshing In the window that appears there is the option Unstructured Size Transitions This option defines the transition gradient of element sizes size gradient whose values are between 0 and 1 The greater the size gradient the greater the change in space To test this enter the value 0 4 and click Accept 8 Again select Mesh gt Generate Mesh Instead of pressing the ESC key the center mouse button or the mouse wheel can also be used 102 ASSIGNING ELEMENT SIZES unaltered and click OK 9 A window opens asking whether the previous mesh should be eliminated Click Yes 10 GiD then asks you to enter the maximum element size Leave the default value SSR EEI A CEEI ITN RK NIZE WERE AN OI ESA ON IEC SOS CES ava NN pey NTEN IZIS I ARRAT lt WZ el mA ZY lt i gt N X WA 7 X NEN V ea a __ a e Se YX X Si A Ny atte AA NA 4 l LA AS NW LORRI G gt AN SSeS ARN LERRET TEO JNN Aaa ANTA METOT R RRETAN NY IIS paren SSSS WP E i 0 a Figure 6 Mesh with the elements concentrated around a point with a size gradient of 0 8 11 The size gradient 0 4 results in a higher density around the point see
87. he screen by choosing in the Mouse Menu Zoom gt Frame This option is also available in the toolbar 30 INITIATION TO GID Finish the square by creating point 10 10 0 and the lines that join this point with points 2 and 3 3 0 10 0 1 0 0 0 2 10 0 0 Now we will create the surface that these four lines define To do this access the create surface command by choosing Geometry gt Create gt NURBS surface gt By contour This option is also available in the toolbar GiD then asks the user to define the 4 lines that describe the contour of the surface Select the lines using the cursor on the screen either by choosing them one by one or selecting them all with a window Next press Escape As can be seen below the new surface is created and appears as a smaller magenta colored square drawn inside the original four lines Once the surface has been created the mesh can be created in the same way as was done for the line From the Top Menu select Mesh gt Generate mesh An Auxiliary Window appears which asks for the maximum size of the element in this example defined as 1 GID USER MANUAL 31 e d AS P K K J i 1 I L L D A p i ZON 7 j m ae a Pe ae De e A Sass Pec f P J f A f X lt fi j La 4 IN j f 5 x oN RAN We can see that the lines containing elements of two nodes have not been meshed Rather the mesh generated over the surface consist
88. he zone near point number 3 Select Label gt All in gt Points The result is shown in Figure 15 Figure 15 Each number identifies a node There is a node for each element vertex The node identifiers created by generating the mesh appear on the screen There is one identifier for each vertex of each element Select Mesh gt Quadratic elements gt Quadratic Select Mesh gt Generate mesh A window opens asking whether the previous mesh should be eliminated Click Yes Another window appears in which the maximum element size should be entered Leave the default value unaltered and click OK Once the mesh has been generated select Label gt All in gt Points The result is shown in Figure 16 Now there are not only nodes at the vertices but also at the midpoints of the edges of the elements Select Mesh gt Quadratic elements gt Quadratic9 10 Select Mesh gt Generate mesh Tg NOTE By default GiD meshes with first degree linear elements To find out which mode GiD is working in select Mesh gt Quadratic elements and it is the flagged option GID USER MANUAL 127 Figure 16 Each number identifies a node There is a node at ee element vertex and at the midpoint of each edge 11 A window opens asking whether the previous mesh should be eliminated Click Yes 12 Another window appears in which the maximum element size should be entered Lea
89. ic vertices GID USER MANUAL 175 Figure 23 10 Select Geometry gt Create gt NURBS surface gt By contour Select the lines Press ESC 11 Magnify the zone indicated in Figure 25 i See av i Figure 24 12 There are two surfaces that overlap each other at one end Figure 26 176 IMPORTING FILES Figure 25 The magnified zone with two overlapping surfaces 13 In this case the best solution for correcting the boundary is to trim the overlap Select Geometry Create gt NURBS Surface gt Trimmed 14 Select the surface to be trimmed Then select the new boundary Figure 27 Figure 26 The surface to be trimmed and the new boundary 15 Select Geometry gt Delete gt Surfaces Select the original surface Figure 28 Press ESC GID USER MANUAL 177 Figure 27 Th 16 Use Geometry gt Delete gt Lines and Geometry gt Delete gt Points to select the lines and points that belong to the surface that has been trimmed and which no longer belong to any surface Figure 29 Figure 28 Lines and point that no longer belong to any surface 178 IMPORTING FILES 17 Select Mesh gt Generate Mesh Then visualize the result using the option Mesh gt View mesh boundary i Da t i f it re y Figure 29 The mesh visualized with the option Mesh gt View mesh boundary 18 A conformal mesh has been achieved GID USER MANUAL 179 3 3 Creating a non conformal mesh J4 NOTE Non conformal meshes
90. iew Results window choose the Contour Fill option A set of available result are displayed View Results amp Deformation Eg View Results amp Deformation Eg View results Main Mesh Reference mesh View results Main Mech Feterence mezh View No Result Y Step View Contour Fill Shep Analysis LOAD ANALYSIS i x Analysis LOAD ANALYSIS oe o PEA factor factor Apply Close roa pee Figure 9 The View Results window 12 Now choose the MC DISTANCE result and click Apply A graphic representation of the calculation is obtained see Figure 10 GID USER MANUAL 203 Figure 10 Visualizing the distance MC DISTANCE from the center of mass of the object to each element for an object of homogeneous material 13 The results shown on the screen reproduce those we anticipated at the outset of the problem the center of mass of an object made of homogeneous material coincides with its geometric center The boh file will provide the exact coordinates of this point 204 DEFINING A PROBLEM TYPE 3 2 Executing the calculation for an object made of heterogeneous material 1 Choose the Files gt preprocess option 2 Choose the Data gt Materials option The Materials window is opened From the Materials menu in this window choose Steel Figure 11 Materials Steel M qa x i Density 7850 Assign Draw Unassign Import Export Close Figure 11 The Materials window with
91. ilep char buffer 80 fgets buffer 80 filep Executing the Jumpline function GID USER MANUAL double N int imat int x xA malloc Nnodti sizeof double y double Ny malloc MUN iqhove Galle e Sev atous double Loi malloc Nelemt iN eo Stibyvouk anauey ae ao eel oc NelemtI sizeof 1nt if error strcpy fileerr projname Streator ree ilies ferr fopen fileerr w de tote anise wie err HAm ya yn sanes Forinti Terr Scr buns for IO e eit jumpline fp reading the coordinates for inod 1 inod lt Nnod inod t rscant fo 20 alri lf aux amp x inoel for i 0 i lt 6g i jumpline fp reading connectivities for ielem 1 ielem lt Nelem ielem t rscant fo g0 amp aux z coe G Op a o aa Scant iar ARON recan o V0 mea til ieleni if imat ielem 0 strcpy fileerr projname Streat Gh eet sett ferr fopen fileerr w de sel Mites ce See er cba Sly ee for dik Oe 1 5 jJumpline fp rscani ip aS iT oS ocd saul sauz2 amp Nmat LE If LE LE DEFINING A PROBLEM TYPE x NULL y i N NULL N NULL ERROR Not enough memory mey tOo Calculare with less elements Vins je amp y inod amp N ielem 1 3 J error 1 error 1 error 1 error 1 KkKKKK Nae uya ya ya SaREOR Elements with no meter L ss Mint g GID USER MANUA
92. in one of its principal phases the preprocess and will include the consequent data and parameter description of the problem This example introduces creation manipulation and meshing of the geometrical entities used in GiD First we will create a line and the mesh corresponding to the line Next we will save the project and it will be described in the GiD data base form Starting from this line we will create a square surface which will be meshed to obtain a surface mesh Finally we will use this surface to create a cubic volume from which a volume mesh can then be generated 1 CREATION AND MESHING OF A LINE We will begin the example creating a line by defining its origin and end points points 1 and 2 in the following figure whose coordinates are 0 0 0 and 10 0 0 respectively It is important to note that in creating and working with geometric entities GiD follows the following hierarchical order point line surface and volume To begin working with the program open GiD and a new GiD project is created automatically From this new database we will first generate points 1 and 2 GID USER MANUAL 25 Next we will create points 1 and 2 To do this we will use an Auxiliary Window that will allow us to simply describe the points by entering coordinates It is accessed by the following sequence Utilities gt Tools gt Coordinates Window Then from the Top Menu select Geometry Create Point In the coordinate
93. in this case From now on all f Pi Cel the entities created will belong to this layer Hi Hew Delete Rename alphabetic To back Gend To Close Figure 1 The Layers window GID USER MANUAL 15 2 CREATING THE AUXILIARY LINES The auxiliary lines used in this project are those that make it possible to determine the center of rotation and the tangential center which will be used later to create the model 2 1 Creating the axes mak T gt Choose the Line option by selecting Geometry gt Create Straight line Enter the coordinate 0 0 in the command line Enter the coordinate 200 0 in the command line Press ESC to indicate that the process of creating the line is finished If the entire line does not appear on the screen use the option Zoom Frame which is located in the GiD Toolbox and in Zoom in the mouse menu Again choose Line Draw a line between points 0 25 and 200 25 The result is shown in Figure 2 Figure 1 Go to the Copy window Figure 4 which is found in Utilities gt Copy Choose Rotation from the Transformation menu and Lines from the Entities Type menu Enter an angle of 60 degrees and click on Two dimensions 1 This option can also be found in the GiD Toolbox i Pressing the ESC key is equivalent to pressing the center mouse button 10 Enter point 200 0 0 in First Point This is the point that defines the center of rotation Click Select to select the f
94. indow appears in which to enter the maximum element size for the mesh to be generated Enter 2 and click OK The mesh shown in Figure 7 will be obtained a i ATTA T SERA AAAI AAA A A A PATAT ATAT ATTE ETETETT ATAN ATANA BOD NTT TTT ATTAT TATT Sh pn CAT AV AV AAV AVATAT AVATAR ATH ms SS F i 4 Say ay WAG s wa we a ee AE Sie eure E o K c 5 l ek i aTa F gad ey a as A ee eS ary E c E gt a gt a a B al E E gt a gt E A E M M N E E M a ae DON 27 ee ee RE T a TET TA A A A 9 ATANT ITET NANET TATATATA E iS A ETTA N E gE it NETANE ATETEA A or a8 be TITEI T T T a e AE AAA E EAEE E A ET GAT ak et he g th a L TTA aaa Ae A EF Figure 7 The mesh of the object 7 Now the calculation may be initiated Choose the Calculate option from the Calculate menu thus executing the calculating module 8 Wait until a box appears indicating that the calculation has finished Figure 8 202 DEFINING A PROBLEM TYPE Process info Process ToMeshzD started at Mon Oct 24 12 41 31 has finished Postprocess Figure 8 Process information box 9 Choose the option Files gt Postprocess 10 From the Windows menu choose the View Results option Figure 9 A window appears from which to visualize the results By default no result is visualized on entering the postprocessing component 11 From the View combo box in the V
95. ing steps some examples are given 1 Start Weight and End Weight refer to the start point and end point of the line oriented as it is drawn when you select it GID USER MANUAL 125 Select Mesh gt Unstructured gt Assign sizes on points A window appears in which to enter the size to be assigned to points Enter 0 1 Select point number 11 and press ESC Another window appears in which to enter the size to be assigned to points In this case we do not want to assign sizes to any other points so click Cancel Select Mesh gt Unstructured gt Assign sizes on lines A window appears in which to enter the size to be assigned to lines Enter 0 5 Select line number 21 and press ESC Another window appears in which to enter the size to be assigned to lines In this case we do not want to assign sizes to any more lines so click Cancel Select Mesh gt Generate mesh A window appears asking whether the previous mesh should be eliminated Click Yes Another window appears in which the maximum element size should be entered Leave the default value unaltered The result is the mesh shown in Figure 14 Figure 14 Unstructured size assigned in point 11 and line 27 126 METHODS FOR GENERATING THE MESH 2 8 Generating the mesh using quadratic elements 1 m SUPRE p 9 Select Zoom7In from the mouse menu this option may also be found in the GiD Toolbox or in the View menu Enlarge one area of the mesh e g t
96. inished Figure 4 Creating a circle around a point 40 0 In GiD the decimals are entered with a point not a comma GID USER MANUAL 47 2 4 Rotating the circle 3 degrees around a point Use the Move window which is located in Utilities gt Move Within the Move menu and from among the Transformation possibilities select Rotation The type of entity to receive the rotation is a surface so from the Entities Type menu choose Surfaces Enter 3 in the Angle box and check the Two dimensions box Provided we define positive rotation in the mathematical sense which is counter clockwise 3 degrees equates to a clockwise rotation of 3 degrees Enter the point 0 0 0 under First Point This is the point that defines the center of rotation Click Select to select the surface that is to rotate which in this case is that of the circle Press ESC or Finish in the Move window to indicate that the selection of surfaces to rotate has been made thus executing the rotation a 6 hl Entities type Surfaces g Transformations Rotation r Angle 3 Degrees First paint Mum x D o y D o ao Z D o W Two dimensions Second point Mum i D o y D o E o o Duplicate entities Do extrude No E s M Maintain layers Multiple copies I Select Cancel Figure 5 The Move window 48 CASE STUDY 1 2 5 Rotating the circle 36 degrees around a point and copying it 1 Use the Copy win
97. ion and Surfaces A translation of 10 units will be made To do this enter two points that define a vector for this translation for example 0 0 0 and 0 0 10 Choose the option Do Extrude Volumes from the Copy window The volume that is defined by the translation will be created Make sure that the Maintain Layers option is not checked Click Select and select the surface of the wheel Press ESC Select the two layers and click them On so that they are visible Choose RenderFlat from the mouse menu to visualize a more realistic version of the model Figure 27 Figure 27 Image of the wheel 60 CASE STUDY 1 5 GENERATING THE MESH Now that the part has been drawn and the volumes created the mesh may be generated First we will generate a simple mesh by default Depending on the form of the entity to be meshed GiD performs an automatic correction of the element size This correction option which by default is activated may be modified in the Meshing card of the Preferences window under the option Automatic correct sizes Automatic correction is sometimes not sufficient In such cases it must be indicated where a more precise mesh is needed Thus in this example we will increase the concentration of elements along the profile of the wheel by following two methods 1 assigning element sizes around points and 2 assigning element sizes around lines 5 1 Generating the mesh by default 1 Choose Mesh gt Generate Mesh
98. irst line we drawn After making the selection press ESC or Finish in the Copy window to indicate that the selection of lines to be rotated is finished The result is shown in Figure 3 Figure 2 Creating the axes CASE STUDY 2 LET x Entities type Lines al Transformation Rotation Angle 60 Degrees First point a Mur i 200 y D o z D o M Tio dimensions Second point Mum w D o y D o o D o Duplicate entities Do extrude No Create contacts iw Maintain layers Multionle copies 1 Select Cancel Figure 3 The Copy window GID USER MANUAL T7 2 2 Creating the tangential center peor Choose the menu option Geometry gt Create gt Straight line On the mouse menu choose Contextual and use Join Ctrl a to select points 0 0 and 0 25 Press ESC In the Copy window choose Rotation from the Transformation menu and Lines from the Entities Type menu Enter an angle of 120 degrees and the coordinates 0 25 0 in First point also check the Two dimensions option Finally select last line created In the Copy window choose Translation from the Transformation menu and Lines from the Entities Type menu The translation vector for the translation to be made is the line just created As the first point of the translation select the point farthest from this line segment For the second point select the other point of the line Figure 5 Second point
99. is this file that stores the data which enables GiD to represent the distance of each point from the corresponding center of mass The numerical value of the center of mass is saved in the boh file The accuracy of this value is directly proportional to the element size 216 DEFINING A PROBLEM TYPE strcpy filedat projname strcat filedat boh fptest fopen filedat w fprintf fptest FILE s n projname fprintf fptest CMAS2D n2D routine to calculate the mass center of an heterogeneus object n January 2000 t Rienzi Gianfranco t t t tCIMNE n fprintf fptest n n t gt mass center lf lf n x CG y CG Creating the boh file The boh extension is added to the project name and a file is created that will contain the numerical value of the position of the center of mass which in turn is stored in the x CG and y y_CG variables of the program writing flavia dat strepy filedat projname Sstreatitrviedaty st bavaa dat fp fopen filedat w fprintf fp FILE s n projname fprintf An fprintf CMAS n fprintf Routine to calculate the mass center of an object n fprintf EC t t t tCIMNE n fprintf 2000 G Rienzi n fprintf 6d 6d 3 n Nelem Nnod fprintf t tENODES n for inod 1 inod lt Nnod inod fprintf fp 6d 3 14 6e 14 6e n inod x inod y linod forintt ip FyENECONECTIVITIESII gt for ielem 1 ielem lt Nelem
100. ject entities Toggle geometry mesh view Create line creates straight line Create arc creates an arc GID USER MANUAL 19 Standard toolbar Changes the configuration for Opens the copy Prints the postprocess window current phase Creates a project opens the new preferences project A window Standard Bar X OP BISSMAGYosVsl 4 j Opens the N Reads a previously layers window GiD info created GiD Saves to button project disc all Saves the S information l drawing related to image shown Opens the help the project onthe Lz window Quits GiD screen in one of the following Kya formats 20 PRESENTATION OF GID Geometry and View operations postprocess Zoom in enlarges image area which user indicates by drawing a mouse window m Zoom out reduces image area itch surf which user indicates by drawing a Switch surface sets on or off mouse window ADA Zoom frame places image in center of screen Switch volume sets on or off Switch cut sets on or off ee Do cuts 2 points 3 points succession axis redraw redraws image Rotate trackball rotates the image Pan two points displaces image from one point to another both chosen by the user Set maximum value Contour fill Change light vector direction with this option the user can change the vector of the light direction interactively Set minimum value Contour fill Reset contour li
101. lue 5e6 in the Weight box Click Assign and select the point indicated in Figure 16 Press ESC when this step is finished S ZN Figure 16 The point subject to external weight 5 Choose Mesh gt Generate mesh GID USER MANUAL 207 6 A window appears in which to enter the maximum element size for the mesh to be generated Enter 2 and click OK 7 Choose the Calculate option from the Calculate menu thus executing the calculating module 8 Choose the Files gt Postprocess option 9 Visualize the new results Figure 17 Visualizing the distance MC DISTANCE from the center of mass to each element for an object of heterogeneous material subject to point weight 10 Now the condition is external point weight As anticipated the new center of mass is displaced toward the point under weight 208 4 APPENDIX 4 1 The program code for the calculating module DEFINING A PROBLEM TYPE 1 The structure of the program that calculates the center of mass cmas2d c is the READS the dat file coordinates gt x conectvites gt H densities gt rno conditions node condition value weal out of memary CREATES the err file This file is created only if an error cemcurs element with no materia CALCULATION following i project name dat void input pryect_name er main void calculate L project_nametooh void output project_nam flavladat Oroject_ name flavia r
102. ly small chordal error results in small elements in zones where there is greater curvature Accordingly the approximation of the mesh may be improved in zones with greater curvature by using the option Chordal Error Chordal Error generates an increased number of elements in zones where there is curvature One way of obtaining accurate meshes with few elements is using structured elements in zones where there is curvature The option Allow automatic structured located in Preferences may be combined with the option of limiting the chordal error thus achieving an accurate mesh with fewer elements It only makes sense to use Allow automatic structured when working with a non conformal mesh Tg NOTE The option Allow automatic structured generates highly distorted elements that might with some calculating modules lead to erroneous results In the case of stamping a plate we recommend using Allow automatic structured with the calculating modules 1 Open Utilities gt Preferences 2 On the Meshing card activate the option Allow automatic structured and enter the value of 0 9 in the box labeled Unstructured size transitions Click Accept The option Unstructured size transitions defines the size gradient of the elements the value ranging from 0 to 1 The greater the value the faster the variation of the element sizes in space and so there will be fewer elements in the mesh GID USER MANUAL 181 Preferences Figure 3
103. mesh on surfaces and volumes Generating a semi structured volume mesh Generating a mesh using quadratic elements 112 METHODS FOR GENERATING THE MESH 1 INTRODUCTION In order to carry out this example start from the project ToMesh3 gid This project contains a geometry that will be meshed using different types of elements 1 1 Reading the initial project 1 Inthe Files menu select Read Select the project ToMesh3 gid and click Open 2 The geometry appears on the screen It is a set of surfaces and three volumes Select Render gt Flat from the mouse menu or from the View menu In Figure 1 shows the geometrical model loaded 3 Select Rotate gt Trackball from the mouse menu This option is also available in the GiD Toolbox Make several changes in the perspective so as to get a good idea of the geometry involved Figure 1 Contents of the project ToMesh3 gid 4 Finally return to the normal visualization Render gt Normal This mode is more user friendly The mouse menu appears when the right mouse button is clicked GID USER MANUAL 113 2 GENERATING THE MESH TYPES OF MESHES Using GiD the mesh may be generated in different ways depending on the needs of each project The two basic types of meshes are the structured mesh and the unstructured mesh For volumes only there is one additional type the semi structured mesh For all these types of mesh a variety of elements may be used linear ones
104. meshes by default but tetrahedron structured meshes can also be assigned Select Mesh gt Element type gt Tetrahedra and then select volume number 2 Select Mesh gt Generate mesh A window appears asking whether the previous mesh should be eliminated Click Yes Another window comes up in which to enter the maximum element size Leave the default value unaltered and click OK The result is the mesh shown in Figure 8 GID can obtain volume structured meshes made of hexahedra tetrahedra or prisms As can be seen in Figures 8 and 9 there are two kinds of tetrahedron structured mesh the one shown in Figure 8 is obtained when the option Utilities gt Preferences gt Meshing gt Symmetrical structured tetrahedra is set If this option is not set the mesh presented in Figure 9 is produced with fewer nodes than if using the previous option also it is not topologically symmetrical Figure 9 Structured volume mesh of tetrahedra with the option Symmetrical structured tetrahedra not set GID USER MANUAL 121 2 6 Generating semi structured meshes volumes a ead To mesh volumes with a semi structured mesh select the option Mesh gt SemiStructured gt Volumes A window appears in which to enter the number of divisions for the direction in which it is structured the prismatic one Enter 8 Select volume 3 and press ESC As volume 3 is prismatic in one direction only i e parallel to Y axis GiD will automatically detect this fact a
105. mit Display style values Contour fill how volumes surfaces and cuts should be drawn SV List entities permits Culling style listing of project entities none front faces back faces or front and back Faces GID USER MANUAL 21 3 MOUSE MENU The Mouse Menu is the auxiliary menu which appears by clicking on the right mouse button while the cursor is over the GiD screen The Mouse Menu permits the user to quickly access various image placement and viewing commands to facilitate easy management and definition of the project Furthermore the Mouse Menu contains the Contextual menu which permits the user to access to all options available in previously performed commands The option Contextual is only available after the user has performed a command from the Top Menu User can access options available in each distinct Offers various zoom options command once they have W In for viewing of piece been executed ZA Out Dynamic Previous y Next Rs Frame Offers various rotation options Trackball Contextual Screen axes Object axes mcrae b Center Permits translations of the Plane XY Original Rotate J image from one point to Plane XZ Pan another two points or Plane YZ Fi dynamically dynamic Isometric ie Redraw y y y Render Two point a Lelie b Fa Dynamic Redraws geometry of the Layer project Offers various illumination p Image to clipboard options for the image
106. mita Deformation Static analysis Endless animation W Delay 200 ms profile or Send to Close Graphs Window x Create General Options Graph Management Views Point Evol Analysis Estatic k Step 1 ma m anis All steps Y anis All step at E static Displacements M Reactions bis M Reactions Apply Close Several Results x Results view one byone C one over another Current list of results Delete 18 PRESENTATION OF GID 2 TOOLBARS Option Utilities gt Graphical gt Toolbars opens a window where it s possible to configure the toolbars position or switch them on and off Geometry and View operations preprocess Zoom in enlarges image area which Create NURBS line creates a line of user indicates by drawing a mouse type NURBS window Create polyline creates polyline a apart from other lines l Create NURBS surface creates a a ___ NURBS sa defined by border ines Zoom out reduces image area which user indicates by drawing a mouse window Zoom frame places image in center of screen Redraw redraws image Create volume creates a volume Rotate trackball rotates the image e reae object rectangle circle polygon sphere cylinder cone a prism thorus Pan two points displaces image from one point to another both hs chosen by the user Delete deletes entities List entities permits listing of pro
107. n The center of the rotation is the intersection of the axes namely point 200 0 Ensure the Do Extrude menu is set to No 2 Click Select and select all the surfaces except those defining the elbow of the pipe Press ESC when the selection is finished _ TEN ott tL im Figure 17 Geometry of the two pipes and the auxiliary lines B60 CASE STUDY 2 3 5 Creating the end of the pipe 1 From the Copy window select Surfaces and Rotation Enter an angle of 180 degrees Since the rotation may be done in 2D choose the option Two Dimensions The center of rotation is the upper right point of the pipe elbow Make sure the Do Extrude menu is set to No 2 Click Select and select the surfaces that join the two pipe sections 3 Inthe Move window select Surfaces and Translation The points defining the translation vector are circled in Figure 19 4 Click Select and select the surfaces to be moved Press ESC The result should be as is shown in Figure 20 tart meinen Figure 18 The circled points define the Figure 19 The final position of the translated translation vector elbow Choose Geometry gt Create gt NURBS surface gt By contour and select the four lines that define the opening of the pipe Figure 21 Press ESC From the Files menu choose Save in order to save the file Enter a name for the file and click Save Figure 20 Opening the end of the pipe GID USER MANUAL 87 4 CREATING THE SECOND COMPONENT PA
108. n fileerr w fprintf ferr n n n ERROR Not enough memory x n fprintf ferr Try to calculate with less elements n GID USER MANUAL 211 exit 1 for i 0 i lt 6 i jumpline fp Space is reserved for storing the coordinates of the nodes pointers x y the connectivities pointer N and the materials corresponding to each element pointer imat In case of error insufficient memory a file is created with the extension err This file contains information about the error and the program is aborted The next six lines are jumped over reading the coordinates for inod 1 inod lt Nnod inod t fscanf fp od 1f 1f amp aux amp x inod amp y inod for i 0 i lt 6 i jumpline fp The coordinates of the nodes are read and stored in the x and y variables The node identifier indexes the tables of coordinates reading connectivities for ielem 1 ielem lt Nelem ielem fscanf fp 3d amp aux for JjJ 0 J lt 3 J fscanf fp d amp N ielem 1 3 j fscanf fp Sd amp imat ielem a ES if imat ielem 0 strepy fileerr projname strcat fileerr err ferr fopen fileerr w fprintf ferr n n n ERROR Elements with no material n exit 1 The connectivities are read and the N variable is saved This variable is a Nelem x 3 size table with two fields The nodes 3 nodes forming
109. nd which define the line Finally press Escape to indicate that the creation of the line is completed Tg NOTE It is important to note that the Contextual submenu in the Mouse Menu will always offer the options of the command that is currently being used In this case the corresponding submenu for line creation has the following options Contextual Baze Join Ctrl a Zoom Foint In Line Rotate j Point In Surface Par b Tangent In Line A Normal In Surface te Hadaw Arc Center Render Options Label Hew Layer Old lt Escape Image to clipboard Quit GID USER MANUAL 2 Once the geometry has been created we can proceed to the line meshing In this example this operation will be presented in the simplest and most automatic way that GiD permits To do this from the Top Menu select Mesh gt Generate mesh And an Auxiliary Window appears in which the size of the elements should be defined by the user Tg NOTE The size of an element with two nodes is the length of the element For surfaces or volumes the size is the mean length of the edge of the element In this example the size of the element is defined in concordance with the length of the line chosen for this case as size 1 Enter value window x Enter size of elements to be generated fo Ok Cancel Automatically GiD generates a mesh for the line The finite element mesh is presented on the screen in a green color The mesh is formed by
110. nd will select it to be the direction in which the semi structured volume mesh is structured Another window appears in which to enter the number of divisions in the direction of the structure In this case we do not want to select any more volumes so click Cancel Select Mesh gt Generate mesh A window appears asking whether the previous mesh should be eliminated Click Yes Another window appears in which to enter the maximum element size Leave the default value unaltered and click OK The result is the mesh shown in Figure 10 Figure 10 Semi structured volume mesh of tetrahedra Only volumes that are topologically prismatic can be meshed with a semi structured mesh 122 METHODS FOR GENERATING THE MESH As can be seen volume 3 has been meshed with tetrahedra Semi structured volumes are meshed with prisms by default However in this case it was not possible because of volume 2 which has tetrahedra assigned and shares one surface with volume 3 In the following steps a hexahedron mesh is produced 8 Select Mesh gt Element type gt Hexahedra 9 Select volumes 2 and 3 and press ESC 10 Select Mesh gt Generate mesh 11 A window opens asking whether the previous mesh should be eliminated Click Yes 12 Another window appears in which to enter the maximum element size Leave the default value unaltered and click OK The result is the mesh shown in Figure 11 Figure 11 Semi structured volume mesh of hexahedra In case
111. ng points with the mouse 50 2 7 Intersecting lines Choose the option Geometry gt Edit gt Intersection Line line Select the upper circle resulting from the 36 degree rotation executed in section 2 5 Select the line resulting from the 33 degree rotation executed in section 2 6 see Figure 10 Press ESC to conclude the intersection of lines Create a line between point 55 0 and the point generated by the intersection To select the points use the option Join Ctrl a in the Contextual menu Choose the option Geometry gt Edit gt Intersection gt Line line in order to make another intersection between the lower circle and the line segment between point 40 0 and point 55 0 see Figure 11 Then continue selecting to make an intersection between the upper circle and the farthest segment of the line that was rotated 36 degrees see Figure 12 CASE STUDY 1 Figure 10 The two lines selected 2 Figure 11 Intersecting lines Figure 12 Intersecting lines GID USER MANUAL 51 2 8 Creating an arc tangential to two lines Choose Geometry gt Create gt Arc Fillet curves 2 Enter a radius of 1 35 in the command line See footnote 2 on page 4 3 Now select the two line segments shown in Figure 13 Then press ESC to indicate that the process of creating the arcs is finished Figure 13 The line segments to be selected 2 9 Translating the definitive lines to the profile layer 1
112. nough By selecting Mesh gt Draw Skip entities Rjump the entities that RJump is going to skip and the ones that it is not going to skip are displayed in different colors In this chapter we will see the properties of this mesher 1 2 oat Select Mesh gt Reset mesh data to reset all mesh sizes introduced previously A window appears advising that all the mesh information is going to be erased Press Go to Utilities and open Preferences Click Meshing In the window that appears you can choose between the three surface meshers available in GiD RFast RSurf and RJump Select RJump mesher Click Accept Select Mesh gt Generate Mesh A window opens asking if the previous mesh should be eliminated Click Yes Another window appears in which you can enter a maximum element size Leave the default value unaltered and click OK This results in a mesh where contact lines between surfaces that are tangent enough do not have nodes contact points between lines tangent enough are also skipped when meshing see Figure 10 et AP T X as Meee eee SSS Ss T EEA NE SSE Too a AS K w i i iN N N A Figure 10 Mesh using the RJump mesher GID USER MANUAL 107 Note that the smaller elements shown in Figure 3 do not appear in this mesh because of the properties this mesher f 8 9 1 11 12 13 0 Using the RJump mesher it is possible to assign sizes to
113. o install Ramsolid select Data gt Problem type7linternet Retrieve A window with the available modules will appear Select RamSeries Windows which contains Ramsolid and click Retrieve Problem type to install it Retrieve analysis Problem types l X Hote In order to use this function tt is necessary to be connected to internet Problen type Version Characteristics Famienes 5 5 Wind Structural Analysis of beams shells and 3D solids Structural Analysis of beams shells and 3D solids for Linus Structural Analysis of beams shells and 3D solids for Macintosh Mach Se Multiphysics solver for Windows including fluid flow heat transter spect Multiphysics solver for Linus including fluid flow heat transher species CFO panel code for solving the linearised potential free surface problem Prepostprocessing program with specialized tools for electromagneticsn Statics and dynamic interface beta for NASTRAN analysis program Examples for Nastran 2 0 Interface to Abagus program Calculus program to solve heat problems RamSeries Linux RamSenes Mach Se Tdyn 4 7402 for Wir Tdyn 4 11 for Linus TdynLin GiD CEM 3 0 Linus Nastran 3 1 1 Nastran examples Abaqus Caltep Ca l l l l I l l l l l Froblem type info Froblem type news Retiewe Froblem type Ja NOTE You can find the finished model on the GiD CD ROM or on the GiD web page http www gidhome com support 1 For further information on Ramsolid
114. odule begins the process which is run in background When the process finishes a new window appears Process info r Process test stated at Wed Oct 26 14 58 31 has finished Postprocess Figure 19 The Process info window 7 Click on Postprocess in order to analyze the results 8 Select View results gt Displacements gt Displacements Figure 20 Displacement results Figure 21 Von Misses results Instead of displacements we can choose View results gt Von Misses 10 Calculating the stresses on the part is especially significant when the surfaces around the tooth are under pressure It is important that the mesh on these surfaces is sufficiently accurate Accordingly a smaller sized element will be assigned to these surfaces For further information about the calculation process select Calculate Window A window appears indicating the moment when the calculation began and its PID To close this window click Kill 142 POSTPROCESSING A RATCHET WHEEL 11 Before we continue we need to obtain temporary passwords for both GiD and Ramseries in order to work with larger meshes If you already have the passwords skip this step if not follow these steps a Obtain a temporary password for GiD at http www gidhome com password b Obtain a temporal password for Ramseries at http www compassis com 12 Return to GiD Preprocess go to Utilities gt Preferences gt Meshing and press Reset Another possibility is to select th
115. of the err file indicates that the calculation is considered satisfactory GiD automatically deletes the err files before initiating a calculation to avoid confusion 3 cmas2d exe 2 1 Executing the cmas2d exe file cmas2d bat QECHO OFF del 2 1 boh del 2 1 flavia res del 2 1 flavia dat rem OutputFiles 32 sl boh rem HErorh i hey 325 lett 3 cmas2d exe 2 1 200 DEFINING A PROBLEM TYPE 3 EXECUTING THE CALCULATING MODULE In order to more easily understand the way the calculating module works simple problems with limited practical use have been chosen Although these problems do not exemplify the full potential of the GiD program the user may intuit their answers and therefore compare the predicted results with those obtained in the simulations 3 1 Executing the calculation for an object made of homogeneous material 1 From the Files menu select Read Select the file ToMesh2d gid and click Open SA ZN Figure 5 Contents of the ToMesh2d giad file 2 Choose the option Data gt Problem type gt Cmas2d 3 Choose Data gt Materials The materials window is opened Figure 6 From the Materials menu in this window choose the option Air GID USER MANUAL 201 Materials Assign Draw Unassign Import Export Figure 6 The Materials window 4 Click Assign gt Surfaces and select all the surfaces Press ESC when this step is finished 5 Choose the Mesh gt Generate option 6 A w
116. oint number 29 as it was done in chapter 2 2 1 2 Select Mesh gt Mesh criteria gt No skip lines and select line number 43 Press ESC Select Mesh gt Draw Skip entities Rjump to display the entities that will and will not be skipped in different colors As is shown in Figure 12 line 43 will now not be skipped the rest of the lines are unaffected and RJump will either skip or mesh them according to its criteria Rjump Skip No Skip LA w ill Figure 12 Entities that will be skipped and not skipped using the RJump mesher Select Mesh gt Unstructured gt Assign size on points A window appears in which to enter the element size around the points to be chosen Enter 0 1 and click OK Select the point indicated in Figure 4 point number 29 Press ESC to indicate that the selection of points is finished Select Mesh gt Generate Mesh A window opens asking if the previous mesh should be eliminated Click Yes 109 GID USER MANUAL 7 Another window appears in which you can enter a maximum element size Leave the default value unaltered and click OK This results in a mesh like the one obtained before in Figure 10 but with high concentration of elements around point number 29 Note that there are nodes on line number 43 because we have forced RJump not to skip this line see Figure 13 1 Mai h S rail v Wan AN ET N TARN So
117. ojname strcat filedat flavia res fp fopen filedat w fprintf fp MC DLSTANCE 2 for inod 1 inod lt Nnod inod distance from the center of masses raiz x CG x inod x CG x inod y CG y inod y_ CG y inod pot sqrt double raiz fprintf fp 26d 14 6lf n inod pot fclose fclose fp fptest free x free y free N free imat Creating the flavia res file The output data results are stored in this file 218 DEFINING A PROBLEM TYPE The format of the flavia res file is as follows e On the first line enter the variables defining the type of result The first parameter of the line is the title appearing in the GiD post process menu For this example the title MC DISTANCE has been chosen Then enter the values 2 1 1 it 0 The first parameter is the type of analysis 2 corresponds to a load analysis The second parameter is the number of steps in the calculation In this example there is 1 step The third parameter is the type of result 1 corresponds to a scalar result The fourth parameter is the position associated to the results 1 means the results are associated with nodes The fifth parameter is a description of each component 0 means there is no description e To conclude list the results distance from the center of mass in the following format Node identifier inod associated result pot jumpline function void jumpline FILE f
118. ons are displayed Signal problematic point More help or List The first option is the same as the Signal button while the List option presents a list of the problematic geometrical entities to make selection easier when performing some common procedures like sending the entities to a separate layer erasing the entities etc The More help option gives advice about to correct the geometrical model so the mesh can be generated Ig NOTE The Mesh Errors window can be recovered while dealing with the model by selecting the Show errors option in the Mesh menu Figure 7 Signaling the surface number 124 Ig NOTE The identifiers of the entities vary each time the instruction Mesh gt Generate Mesh is executed 166 IMPORTING FILES 2 2 Correcting surfaces 1 With the View gt Zoom gt In option on the mouse menu magnify the zone around surface 124 Figure 8 An enlargement of the zone around the surface 124 2 Select Label gt All from the contextual menu On inspection we see a blur of numbers due to a high concentration of entities at one end of the surface Magnify this zone even further Figure 9 1 This option is also found in the GiD Toolbox GID USER MANUAL 167 Figure 9 A second enlargement of the blurred zone 3 Several line segments are superimposed over each other thus creating an incorrect surface boundary Select Geometry gt Edit g
119. or Since the pipe section must measure 40 length units the vector is defined by points 0 0 0 and 40 O 0 7 From the Do extrude menu choose the Surfaces option CASE STUDY 2 8 Click Select to select the lines that define the cross section of the pipe Press ESC to conclude the selection process Figure 23 Creating a pipe by extruding circumferences 4 2 Creating the other pipe section 1 Choose Geometry gt Create gt Point and enter points 20 9 and 20 11 Press ESC to conclude the creation of points 2 From the Copy window select Points and Rotation Enter an angle of 180 degrees and from the Do extrude menu select Lines Since the rotation can be done on the xy plane choose Two Dimensions The center of rotation is the coordinates 20 0 0 3 Click Select and select the two points just created Repeat the process this time entering an angle of 180 degrees 4 From the Copy window select Lines and Translation In First Point and Second Point enter the points defining the translation vector Since this pipe section must also measure 40 length units the vector is defined by points 0 0 0 and 0 0 40 5 From the Do extrude menu select the Surfaces option 6 Click Select to select the lines that define the cross section of the second pipe Press ESC to conclude the selection Figure 24 A rendering of the two intersecting pipes GID USER MANUAL 4 3 Creating the lines of intersection
120. ormats aa GID mesh Fecent files Surface mesh PSVEPS Screen PS EPS Vectorial l Eater Mie Cao CER eee Insert Gil geometry BMP GIF u Export files PHG TGA IGES z Closes GiD Window to set up 3 TIFF eit DXF VRML ae ACIS properties and image properties GID mesh Printing options Text data report ASCII project Open the ON layers last models Calculation file Ctrl x Ctrl c Using Template bas only mesh GID USER MANUAL 5 View In the view menu also available from the mouse menu there are all the visualization commands These commands change the way to display the information in the graphical window but they do not change any definition of the geometry or any other data Offers various rotation options 4 Trackball Screen axes Object ares Yje Center oom Plane Y Original Rotate Plane 2 Fan Plane v2 Isometric ta Redraw ao Render Perspectye Redraws geometry of the project Background image entities for preprocess as well for postprocess Image to clipboard Multiple windows Opens a file image as a background Mode Fit screen Real size Default Copy the image to the clipboard Switch the visualization mode to geometry mesh or postprocess Offers various zoom options F for viewing of piece To change to a eae F projection Normals Set the near and far clippin Higher entities
121. planes aD View Show numbering of the b lo S ut kK Dynarnic Previous Henst Permits translations of the image from one point to another two points or dynamically dynamic Two paint at Dynamic Offers various illumination options for the image Normal Flat Smooth Change light dir Customize Draw the surfaces normal sans line tangents Draw by colors the amount of parents of an entity Saves the actual position of the current view permits to have Save Read several views of the same project This option 6 PRESENTATION OF GID Geometry Geometry permits the user to create delete edit and model geometry Changes from the mesh viewing to the geometry Geometry Creates drawing entities View geometry a Poirit Deletes entities Create Ig Delete So Straight line Points Edit b 2 NURBS line ens Parametric line ee Ae Folyline OMNES TN AIC All types I NURBS surface Parametric surface Edits and permits changes to entities Contact surface Move point Divide Lines operations wap arc Polyline Surh esh Edit HURBS Convert to NURBS Simply NURBS Hole NURES surface Collapse Uncollapse Intersection Surface boolean op Volume boolean op Surface mesh a Volume j Contact d in Object d GID USER MANUAL Utilities In the Utilities menu GiD allows the user to define preferences or perform operations
122. racy in the discretization of the geometry The chordal error is the distance between the element generated by the meshing process and the real profile of the model By selecting a sufficiently small chordal error the elements will be smaller in the zones with greater curvature 6 1 Generating the mesh using Chordal Error oe a a Choose the option Mesh gt Unstructured gt Sizes by Chordal error Enter 1 for the minimum element size Enter 15 for the maximum element size Enter 0 2 for the chordal error Choose Mesh gt Generate mesh A window opens in which to enter the maximum element size of the mesh to be generated Leave the default value provided by GiD unaltered and click OK When the meshing process is finished a window appears with information about the mesh that has been generated Click OK to visualize the mesh Choose Mesh gt View Mesh Boundary to see only the contour of the volumes meshed but not the interiors The visualization may be rendered using the various options in the Render menu located in the mouse menu Figure 30 The mesh generated for the piece Tg NOTE By default GiD corrects element size depending on the form of the entity to mesh This correction option may be deactivated or reactivated in the Meshing card in the Preferences window under the option Automatic correct sizes GID USER MANUAL 95 6 2 Generating the mesh by assignment of sizes on surfaces 1 Choose Mesh gt Unstructured gt Assi
123. ries5 5 gt ramsolid Problem type ansys55 gt cmas2d Constraints Examples gt Contact ramseries5 5 zej rambshell EE ramsolid Masses Transform riba tooa Internet Retrieve Load Load cases Unload Debugger Static loads Dynamic loads Properties Problem data Advanced Reports Verify assigned properties Local axes 2 Choose Data gt Constraints A window appears in which the problem constraints are entered 3 We are dealing with constraints acting on surfaces the surface symbol lt I must be clicked x x Ti a IG Constraints Ch Local PressueLoad hi a Flags Values Units N m kg Local anes GLOBAL i Normal inwards 2e8 W Constraint W Y Constraint W 2 Constraint Assign Entities Draw Unazsign Assign Entities Draw Unassign Close Close Figure 9 The Constraints window Figure 10 The Static Loads window with the Local Pressure Load option selected over surfaces 136 POSTPROCESSING A RATCHET WHEEL 4 Inthe Constraints window click Assign Select the two surfaces that are the ends of the axle then press ESC or Finish in the Constraints window Figure 11 Selecting the surfaces that are the ends of the axle 5 Choose the Draw option from the menu in the Constraints window Then select the colors option See Figure 12 _ x rey L CAN Ne a Figure 12 Visualization of the condition applied
124. round lines GID USER MANUAL 67 6 OPTIMIZING THE DESIGN OF THE PART The part we have designed can be optimized thus achieving a more efficient product Given that the part will rotate clockwise reshaping the upper part of the teeth could reduce the weight of the part as well as increase its resistance We could also modify the profile of the hole in order to increase resistance in zones under axle pressure To carry out these optimizations we will use new tools such as NURBS lines The final steps in this process will be generating a mesh and visualizing the changes made relative to the previous design This example begins with a file named optimizacion gid 6 1 Modifying the profile 1 Choose Read from the Files menu and open the file optimizacion gid 2 The file contents appear on the screen In order to work more comfortably select Zoom In thus magnifying the image This option is located both in the GiD Toolbox and in the mouse menu under Zoom Figure 39 Contents of the file optimizacion gid 3 Make sure that the aux layer is activated 4 Choose Geometry gt Edit gt Divide gt Lines gt Num Divisions This option divides a line into a specified number of segments 5 A window comes up in which to enter the number of partitions Enter 8 6 Select the line segment from the upper part of a tooth Figure 39 and press ESC 68 CASE STUDY 1 Using the option Geometry gt Create gt Point and cre
125. rspective 4 Choose Geometry gt Create gt NURBS surface gt By contour Select the lines that form the displaced octagon and press ESC to conclude the selection Again press ESC to exit the function of creating the surfaces Figure 24 The surface created on the translated octagon 58 CASE STUDY 1 5 In the Copy window choose Translation and Surfaces Make a translation of 110 units Enter two points that define a vector for this translation for example 0 0 0 and 0 0 110 6 To create the volume defined by the translation select Do Extrude Volumes in the Copy window 7 Click Select and select the surface of the octagon Press ESC The result is shown in Figure 25 Figure 25 Creation of the volume of the prism 8 Choose the option Render gt Flat from the mouse menu to visualize a more realistic version of the model Then return to the normal visualization using Render gt Normal Figure 26 Visualization of the prism with the option Render Flat Tg NOTE The Color option in the Layers window lets you define the color of the selected layer This color is then used in the rendering of elements in that layer GID USER MANUAL 59 4 3 Creating the volume of the wheel 1 p i eee Visualize the profile layer and activate it The volume of the wheel will be created in this layer Deactivate the prism layer in order to make the selection of the entities easier In the Copy window choose Translat
126. s 210 DEFINING A PROBLEM TYPE The input function reads the dat file generated by GiD The dat file contains information about the mesh The calculate function read and processes the data and generates the results The output function creates the results files void input char filedat 1024 saul 1024 sau2 1024 FILE fp Int aux Jj Void jumpline FILE Strepy filedat projname Streat filedat dat fp fopen filedat r The input function The first part of the input function links the project name with the dat extension thus obtaining the name of the file that is to be read This file is opened in order to be read The jumpline FILE function is declared This function reads 80 bytes of the file that it receives as a parameter It will also be used to jump lines of the text when reading the dat file for i 0 i lt 6 i jumpline fp fscanf fp sd sd amp Nelem amp Nnod The first six lines of the dat file are jumped over since these are lines of information for the user see bas file Then the total number of elements and nodes of the project are read and stored in the variables Nelem and Nnod respectively double malloc Nnod 1 sizeof double error 1 double malloc Nnod 1 sizeof double error 1 malloc Nelem 1 3 sizeof int error 1 malloc Nelem 1 sizeof int error 1 strcpy fileerr projname strcat fileerr err ferr fope
127. s lines surfaces and volumes A layer is a grouping of entities Defining layers in computer aided design allows us to work collectively with all the entities in one layer The creation of a profile of the mechanical part in our case study will be carried out with the help of auxiliary lines Two layers will be defined in order to prevent these lines from appearing in the final drawing The lines that define the profile will be assigned to one of the layers called the profile layer while the auxiliary lines will be assigned to the other layer called the aux layer When the design of the part has been completed the entities in the aux layer will be erased 44 CASE STUDY 1 1 2 Creating two new layers Open the layer management window This is found in Utilities gt Layers Create two new layers called aux and profile Enter the name of each layer in the Layers window Figure 1 and click New Choose aux as the activated layer To do this click on aux to highlight it and then click on the Layer To Use button Next to this button the name of the activated layer will appear aux in the present case From now on all the entities created will belong to this layer cavers E profile Laver To use oF aux On Off Color T A Sel Mew Delete Rename alphabetic To back Send To Close Figure 1 The Layers window GID USER MANUAL 45 2 CREATING A PRO
128. s of planes of three nodded triangular elements Ja NOTE GiD meshes by default the entity of highest order with which it is working GiD allows the user to concentrate elements in specified geometry zones Next a brief example will be presented in which the elements are concentrated in the top right corner of the square This operation is realized by assigning a smaller element size to the point in this zone than for the rest of the mesh Select the following sequence Mesh gt Unstructured gt Assign sizes on points The following dialog box appears in which the user can define the size Enter value window xX Q Enter size to assign to points 0 0 to unazsigr D T OO000 Assign Close INITIATION TO GID 32 We must now regenerate the mesh canceling the mesh generated earlier and we obtain the following oy fy a i f AN EN AA my As can be seen in the figure above the elements are concentrated around the chosen point Various possibilities exist for controlling the evolution of the element size which will be presented later in the manual To generate a surface mesh in which the elements are presented uniformly the user can select the option for a structured mesh This guarantees that the same number of elements appears around a node and that the element size is as uniform as possible To generate this type of mesh choose Mesh gt Structured gt Surfaces Using this command the u
129. ser should first select the 4 sided NURBS surface that will be defined by the mesh Then the number of subdivisions for the surface limit lines should be entered Pairs of lines define the partitions in the following way 1 Select 10 2 Select 10 divisions for the more divisions for horizontal lines the vertical lines GID USER MANUAL 33 Tg NOTE GiD only generates structured meshes for surfaces of the type 4 sided surface or NURBS surface When this has been done the mesh is generated in the same way as the unstructured mesh by choosing Mesh gt Generate mesh Assign a general element size of 1 though in this case it is not necessary We can see here that the default element type used by GiD to create a structured mesh is a square element of four nodes rather than a three nodded triangular element To obtain triangular elements the user can specifically define this type of element by choosing Mesh gt Element type Triangle and selecting the surface to mesh as a triangular element Regenerate the mesh and the following figure is obtained 34 INITIATION TO GID GiD also allows the user to concentrate elements in structured meshes This can be done by selecting Mesh gt Structured gt Lines gt Concentrate elements First we must select the lines that need to be assigned an element concentration weight The value of this weight can
130. ss Calculate Calculate Shows details of the Sends the mesh created by Calculate remote calculation process GiD to a remote server a which calculates the results Cancel process Opens the calculate window i View process info Calculate window Interrupts the calculation process GID USER MANUAL 11 Help This menu permits the user to obtain different types of help and information about GiD Interactive help Help on how to configure covering all GiD Help F GiD for a particular type of ti ap analysis oa Customization Help y What is new in Tutorials this version i Wa Fiat i new FAQ GiD tutorials Use this option to register GiD and use Register GID its professional version Frequently asked questions about GiD Register Problem type Register fror file Ask for the file that contains passwords for all calculating modules Register problem types Visit GID web About Go to the official website Gives basic information for GiD and the version being used PRESENTATION OF GID Options Window Help 12 GiD Postprocess Gib Project PuenteRomano Files wiew Utilities Do cuts View results Files This Top Menu of the postprocess phase is the same of that as the preprocess phase and has the same name The user can read and save files save screen images return to preprocess phase options and exit the program Starts a new postprocess project
131. sualizing the results using vectors is also an option A vector is drawn for each element of the mesh In the View Results window choose Display Vectors from the View combo box and Stresses from the results available Then choose the S the great main stress Click Apply Magnify the zone indicated in Figure 35 Figure 36 Si main stresses detail using vectors Now select the All component from the Stresses result Click Apply the result is shown in Figure 388 Red vectors indicate traction tensile stress and blue vectors indicate compression Displacements m Reactions M Stresses Fa Si Sil Sill E factor f 08338e 008 Apply Close Figure 37 Result and scale selection Figure 38 Visualization of all stresses 150 POSTPROCESSING A RATCHET WHEEL 4 2 Modes of visualization 1 Choose Windows View Style A window labeled Select amp Display Style appears in which the options for visualizing the geometry can be changed This window is composed of various menus each characterizing some aspect of the visualization of the model Options from all these menus can be combined to achieve a suitable visualization Tg NOTE In the post processing component the elements of the mesh are classified into Meshes Sets and Cuts A new Set is created for each group of surfaces that share the same material while there is a Mesh for each group of volumes sharing the same material Cuts are sections made into
132. surface and cut sets Humber of Colors Width Intervals Set Limits d Allows user to neia init select the number 50S Reset Limit Values of colors in the i Reset ll b chromatic scale lee Opre size of the Min Options intervals color Color Scale scale etc Smoothing type r Color window User can choose how to view the vectors which define the results Stream lines options kind of label color and delete option T F F0 F F F F Interior ll vectors Number of Colors Change color Color Mode Color Mode d Offset Delete Change Color mona Label Detail Size Size amp detail Defines for result surfaces options GID USER MANUAL Postprocess windows iew Results amp Deformation x View results Main Mesh Reference mesh View Display Vectors v Step Analysis Estate ft b Axial Force a Ns Ny Ney Axial Forcel E factor 9 08221 e 005 Apply Close To back it M d Cs View style Ctrl Yew results Ctrl d Animate Ctrl m Wiew graphs Several Results Results ranges table Results ranges table x Table will be applied to current result Name Y rxav Minimum Maximum Name Apply Close Select amp Display Style x W Volumes W Surfaces W Cuts alphabetic order Style Body Bound Render Smooth Culling None Conditions None Y 17 Results view M Automatic Li
133. t Divide gt Lines gt Near point and then select point 17 to select it go to Contextual in the mouse menu then select the option Join C a Point 17 is the point at which to make the cut 4 Then select line 2869 Press ESC After the cut is made the result will be as illustrated in Figure 11 168 IMPORTING FILES Figure 10 The zone after cutting line 2869 at point 17 5 Now that the lines are precisely connected a local collapse may be executed Select Geometry gt Edit gt Collapse Lines Then select the lines that appear on the screen Figure 11 The situation after collapsing the lines GID USER MANUAL 169 6 After the collapse the surface boundary is correct and the surface may be drawn with the new boundary The labels are no longer needed so click Label gt Off in the contextual menu 7 Select Geometry gt Create gt NURBS surface gt Trimmed Select surface 124 Then select the lines defining the recently repaired boundary Press ESC Figure 12 Surface 123 with its new boundary 8 Select Geometry gt Delete gt Surfaces Select surface 124 and press ESC Figure 13 The surface to be eliminated 9 Correct surface 149 by going through the same steps as with surface 124 170 IMPORTING FILES 10 To begin the second example in this section mesh the geometry again with Mesh gt Generate Mesh 11 A window comes up in which to enter the maximum element size for the mesh to be generated Leave the default
134. t number of elements A semi structured volume mesh is one in which you can distinguish a fixed structure in one direction i e there is a fixed number of divisions However within each division the mesh need not be structured This kind of mesh is only practical for topologically prismatic volumes 114 METHODS FOR GENERATING THE MESH NAY OET PISA LHOTSE NN AN LANNE LA R I 7 INAS SARK X SA FA A ity pya Y W AA Figure 3 Different render styles a surface mesh b volume mesh c surface mesh and volume mesh together surface layer is red and volume layer is blue GID USER MANUAL 115 2 2 Generating the mesh using points 1 Select Mesh gt Element type gt Only points Select volume number one and press ESC To see entity numbers select Label from the mouse menu or from the View menu If you wish the geometrical entity labels to be displayed the view mode needs to be changed to Geometry using View gt Mode gt Geometry this option may also be found in the GiD Toolbox Select Render gt Normal to see the labels 2 Select Mesh gt Generate mesh 3 A window comes up asking whether the previous mesh should be eliminated Click Yes 4 Another window appears in which to enter the maximum element size Leave the default value unaltered and click OK The result is a mesh as illustrated in Figure 4
135. t them Ig NOTE Importing the same file with different versions of GiD might produce slight variations in the results For this study we recommend using from now on the file imported48 gid which contains the original IGES file translated into GiD format 2 1 Meshing by default 1 Select Mesh gt Generate Mesh 2 A window comes up in which to enter the maximum element size for the mesh to be generated Leave the default value provided by GiD unaltered and click OK 3 When the GiD finishes the meshing process an error message appears see Figure 7 This error is due to a defect in the imported geometry As the window shows there have been errors meshing surface number 124 and 149 MeshErrors x SUTaCes wrong surfaces Num Description signal Close Figure 6 Dialog window warning of an error found when meshing surface 124 GID USER MANUAL 165 4 In this part of the tutorial we focus on repairing surface number 124 the other surface number 149 can be corrected by following the same steps a second time It is apparent that the two problems are similar because they are symmetrical surfaces 5 To locate surface 124 select the line 124 couldn t map this point in the dialog box and press the Signal button the same effect is obtained by double clicking over the message with the left mouse button Tg NOTE If user clicks the right button over a message in the Mesh Errors window three opti
136. ta window for configuring of the general conditions of the cmas2d module GID USER MANUAL 2 4 Creating the Conditions File 191 1 Create the cmas2d cnd file which specifies the boundary and or load conditions of the problem type in question In the present case this file is where the concentrated weights on specific points of the geometry are indicated 2 Enter the boundary conditions using the following format CONDITION Name of the condition CONDTYPE Type of entity to which the condition is to be applied This includes the parameters over points over lines over surfaces and over volumes In this example the condition is applied over points CONDMESHTYPE Type of entity of the mesh to which the condition is to be applied The possible parameters are over nodes over body elements or over face elements In this example the condition is applied on nodes QUESTION Name of the parameter of the condition VALUE Default value of the parameter END CONDITION 3 In GiD the information in the cmas2d cnd file is managed in the conditions window Figure 3 which is found in Data gt Conditions cmas2d cnd CONDITION Point Weight CONDTYPE over points CONDMESHTYPE over nodes QUESTION Weight VALUE 0 END CONDITION Conditions Fointw eight F weight fr Assign Entities Draw Unaesign Close Figure 3 The GiD Conditions window for assigning the cmas2d boundary and loa
137. tail of the mesh generated using Chordal Error GID USER MANUAL 73 CASE STUDY 2 IMPLEMENTING A COOLING PIPE This case study shows the modeling of a more complex piece and concludes with a detailed explanation of the corresponding meshing process The piece is a cooling pipe composed of two sections forming a 60 degree angle The modeling process consists of four steps Modeling the main pipes Modeling the elbow between the two main pipes using a different file Importing the elbow to the main file Generating the mesh for the resulting piece At the end of this case study you should be able to use the CAD tools available in GiD as well as the options for generating meshes and visualizing the result CASE STUDY 2 1 WORKING BY LAYERS Various auxiliary lines will be needed in order to draw the part Since these auxiliary lines must not appear in the final drawing they will be in a different layer from the one used for the finished model 1 1 Creating two new layers xi Open the layer management window which is found in the Utilities gt Layers menu Create two new layers called aux and ok Enter the name for each layer in the Layers window Figure 1 and click New Choose aux as the activated layer To do this click on aux to highlight it and then click Layer o use aux on the Layer To Use button The name of n i Un Ott Color the activated layer will appear next to the button aux
138. taining the numerical value of the VON MISSES module for each node selected 69e 656 if i Ny Set i ads Po S 85e 008 Ue H 3 5e t ig Figure 56 Visualizing the numerical values of the VON MISSES module 6 To return to the previous visualization choose Label gt Off from the mouse menu 7 Inthe Select amp Display Style window Figure 53 click Cut1 Off and V perfil On Choose Rotate gt planeXZ from the mouse menu 8 Choose Do cuts gt Cut Plane gt Succession This tool enables you to make a specific number of equidistant cross sections along an axis Enter two points to define the axis see Figure 57 GID USER MANUAL 157 Figure 57 Defining the axis 9 A window appears in which the number of cuts to make can be entered For the present example enter 20 In the Select amp Display Style window Figure 59 click V perfil Off 158 Figure 58 Cuts made using Do cuts Cut POSTPROCESSING A RATCHET WHEEL Select amp Display Style Wo Volumes W Surfaces W Cuts E alphabetic or order F CutSet 1 perfil C Cutset 2 perfil C CutSet 3 perti mr m ai Soh a Bl Mm oe Style Body Lines a Render Flat Culling N None a Conditions None Plane gt Succession with no visualization of To back Send ta Close 10 11 12 13 the results Figure 59 The Select amp Display Style window with a list of all the cuts made Use the Vie
139. th different extensions These files should have the name that GiD designates and should not be changed manually Each time the user selects option save the database will be rewritten with the new information or changes made to the project always maintaining the same name To exit GiD simply choose Files gt Quit To access the example ejemplo gid simply open GiD and select from the Top Menu Files gt Open An Auxiliary Window will appear which allows the user to access and open the directory iniciacion gid GID USER MANUAL 29 2 CREATION AND MESHING OF A SURFACE We will now continue with the creation and meshing of a surface First we will create a second line between points 1 and 3 3 0 10 0 1 0 0 0 2 10 0 0 We will now generate the second line We will now use again the Coordinates Window to enter the points Utilities gt Tools gt Coordinates Window Select the line creation tool in the toolbar Enter point 0 10 0 in the Coordinates Window and click Apply x iS C System Cartesian O Local axes Global m m oo0000 yhd z 000000 Create new point ask Change Use tab Shift tab and Aeturn Apply Close With option Join Contextual mouse menu click over point 1 A line should be created between 0 10 0 and 0 0 0 Press Escape With this a right angle of the square has been defined If the user wants to view everything that has been created to this point the image can be centered on t
140. the geometry during post processing The categories Meshes Sets and Cuts are at the top of the Select amp stile window For each category a color can be chosen using the Color option Each one may be clicked On or Off or deleted Del In the present example there is only one volume and therefore only one Mesh appears It is named Mesh1 The Style Render Culling and Conditions menus as well as the Massive and Transparent options affect the visualization of the entire mesh 2 Try out the various options offered in the Style menu Click Apply to see the results 3 Try out the various options offered in the Culling menu combined with the Conditions menu and the Transparent and Massive options Click Apply to see the results This option is also located in the post process Toolbox For further information about the tools in the Toolbox click on the corresponding icon with the right mouse button GID USER MANUAL 151 Figure 39 Visualization Figure 40 Visualization using Figure 41 Visualization using using Style gt Boundaries Style gt All Lines Style DHidden Lines Figure 42 Visualization Figure 43 Visualization using Figure 44 Visualization using using Style gt Body Style gt Body Bound Style gt Body Lines Figure 45 Culling gt Front Figure 46 Culling gt Front Figure 47 Culling gt None Faces Faces with the Massive option Conditions Geometry and the Transparent option 152 POSTPROCESSING
141. ting the files system Praprocess GiD cna I Fa Fi Fi axe Fa project_name dat bat Results file Postprocess Postprocess mesh files old format mesh file new format 3D 2D project name lavia bon project_name flavia rss project_name flavia msh project_name flavia dat project nare lavia msh Postprocess GiD 188 DEFINING A PROBLEM TYPE 2 IMPLEMENTATION 2 1 Creating the Subdirectory for the Problem Type Create the subdirectory cmas2d gid This subdirectory has a gid extension and will contain all the configuration files and calculating module files prb mat cnd bas bat exe Tg NOTE In Windows systems if you want the problem type to appear in the GiD Data gt Problem type menu create the subdirectory within Problemtypes located in the GiD folder for instance C GiDWin Problemtypes cmas2d gid GID USER MANUAL 189 2 2 Creating the Materials File 1 Create the materials file cmas2d mat This file stores the physical properties of the material under study for the problem type In this case defining the density will be sufficient 2 Enter the materials in the cmas2d mat file using the following format MATERIAL Name of the material without spaces QUESTION Property of the material For this example we are interested in the density of the material VALUE Value of the property END MATERIAL 3 In GiD the information pertaining to the cmas2d mat file is man
142. to the surfaces under pressure GID USER MANUAL 137 6 Click Data gt Static loads and select surfaces lt 7 From the pull down menu select Local Pressure Load This option enables you to define the surfaces under pressure and specify the value of the pressure Enter 2e8 having selected N m kg in the units menu see Figure 10 Click Assign and select the surfaces which will be subject to pressure Figure 13 Surface of a tooth under pressure Figure 14 Visualization of the condition applied to the surfaces under pressure Figure 15 Visualization of all the conditions entered Pressure is applied to a surface in the direction of the normal to the surface If the surface is part of a volume a positive pressure value indicates a force towards the interior of the volume 138 POSTPROCESSING A RATCHET WHEEL 8 The next step is specifying the material of the part Choose Data gt Properties The Properties window appears We want to simulate steel so enter the corresponding values of its Young s Modulus E Poisson Ratio nu and Specific weight Make sure you have selected N m in the units menu xi Solid bh Units N m kg E 2 1e1 1 nU 0 2 Specific weight 78000 Assign Entities Draw Unassign Close Figure 16 The Properties window 9 Click Assign and select the volume of the part Press ESC when the selection is finished 10 Choose the Problem Data option from the Data menu The Problem Dat
143. triangles quadrilaterals tetrahedra hexahedra prisms spheres or points In this tutorial you will become familiarized with the mesh generating combinations available in GiD 2 1 Generating the mesh by default 1 2 3 Select Mesh gt Generate mesh A window comes up in which to enter the maximum element size for the mesh to be generated Leave the default value unaltered and click OK A meshing process window comes up Then another window appears with information about the mesh generated Click OK to visualize the mesh The result is the mesh in Figure 2 There are various surfaces and volumes By default mesh generation in GiD obtains unstructured meshes of triangles on surfaces and tetrahedra on volumes Select Render Flat to see the mesh in render mode As is shown in Figure 3 volume meshes are represented a little bit differently from surface meshes although in both cases triangles are shown If the triangles you see are the boundary of a volume mesh they are shown with black edges that are thicker than surface meshes triangles If the triangles form a boundary volume mesh and at the same time a triangle surface mesh this can be obtained if surfaces are selected with the option Mesh gt Mesh criteria gt Mesh gt Surfaces the wider edges are colored with the color of the surface layer Examples of these different kinds of render are shown in Figure 3 2 A structured mesh is one in which each node is connected to a constan
144. ve the default value unaltered 13 Select Label gt All in gt Points see Figure 17 14 Notice that the four sided elements quadrilaterals also have a node in the center in addition to the nodes at the vertices and midpoints of the edges Similarly hexahedra also have a node at their center point Figure 17 Each number identifies a node There is a node at each vertex at the midpoint of each edge and in the center of quadrilaterals and hexahedra 128 POSTPROCESSING A RATCHET WHEEL A POST PROCESS CASE STUDY POST PROCESSING A RATCHET WHEEL The objective of this case study is to run a post process analysis of a steel ratchet wheel subjected to a set of forces We will observe the stresses on the material and the resulting deformations The analysis is carried out in four steps e Redefining the part e Entering conditions and materials e Generating the mesh for the entire part and calculating the stresses e Visualizing the results By the end of this study you should be able to run a structural analysis of a model subjected to external forces and visualize the results in GiD Post process GID USER MANUAL 129 1 INTRODUCTION The model in this study will be the one created in Tutorial 1 located in the file pieza gid The geometry in this file will be the object of this post process study In order to follow this tutorial the calculating module Ramsolid must be installed T
145. vee idaeale eget Ada ea ab 160 DetininG ay PrODleny type arimei a aes deed ae ees ea eee 183 GID USER MANUAL 1 PRESENTATION OF GID This chapter will introduce the user to the user interface and graphic environment of GiD GiD is a general purpose pre postprocessor for computer analysis All the data geometry and mesh generation can be performed inside Also the visualization of all types of results can be performed It can be adapted to a specific analysis module by the creation of a problem type Typical problems that can be successfully tackled with GiD include most situations in solid and structural mechanics fluid dynamics electromagnetics heat transfer geomechanics etc using finite element finite volume boundary element finite difference or point based meshless numerical procedures 2 PRESENTATION OF GID USER INTERFACE Upon opening GiD the following window appears on the screen GiD Project UNNAMED Gl xf Files View Geometry Utilities Data Mesh Calculate Help OB S oo FI G Y oO BGS a4 GiDVerens Fas Geometry P Z pee on Top menu Meshing ile Fiet View Utilities Postprocess Quit to Ox T AM Eca GQ tz wa A Ws fp F Q ay ee Q jA Toolbars escape Right buttons Command line To change the configuration of toolbars and menus use the toolbars option located in Utilities gt Tools gt Toolbars GID USER MANUAL 3 1 TOP MENU The Top Menu offers various t
146. volume of the optimized design 4 Click On the prism layer GID USER MANUAL 71 7 GENERATING THE MESH FOR THE NEW DESIGN Generating the mesh for the optimized design is more complex In this geometry it is especially important to obtain a precise mesh on the surfaces around the hole and on the surfaces of the teeth Initially we will generate a simple mesh by default Then we will generate a mesh using Chordal Error to obtain a more accurate result 7 1 Generating a mesh for the new design by default 1 Choose the option Mesh gt Generate mesh 2 A window appears in which to enter the maximum element size for the mesh to be generated Leave the default value provided by GiD unaltered and click OK Figure 45 A detail of the mesh generated by default The Chordal Error is the distance between each element generated by the meshing process and the real profile 72 CASE STUDY 1 7 2 Generating a mesh using Chordal Error 1 Choose Mesh gt Unstructured gt Sizes by Chordal error 2 Provide the values shown in figure 46 Assign sizes by chordal error X Chordal Error 0 05 Maxinurn meshing size i Fi Minimum meshing size 0 1 OF Cancel ee Figure 46 Chordal error windows 3 Choose Mesh gt Generate mesh 4 A greatly improved approximation has been achieved in zones containing curves and more specifically along the wheel profile and the profile of the hole see Figure 47 Figure 47 A de
147. w Results window and the Select amp Display Style window to visualize results in the cuts that have been made Tg NOTE With the option Files gt save cut the cuts may be saved in a file in order to be used during another GiD session In the Select amp Display Style window select all the cuts and click Del to delete them Click V perfil On Choose the Rotate gt planeXY option from the mouse menu Choose Do cuts Divide volume sets gt 2 points Using this option the mesh is divided by a plane without cutting the elements The plane may be defined by two or three points and the right or left portion of the model may be selected A new mesh is created that contains the selected portion GID USER MANUAL 159 ii Figure 60 The cutting line 14 Enter two points to define the plane that will divide the part as shown in Figure 60 Click on the right portion of the model to indicate that this is the side to select After clicking V perfil Off the result will be that shown in Figure 61 Figure 61 A visualization of the divided volume using Von Misses and Contour Fill Tg NOTE The dividing tools are classified in three groups Divide volume sets Divide surface sets and Divide lines In the three cases entities may be divided by defining 2 or 3 points 160 IMPORTING FILES IMPORTING FILES A CASE STUDY IMPORTING FILES The objective of this case study is to see how GiD imports files created with other programs
148. window opened previously the following indicated steps should be used Coordinates window xX C System Cartesian g Local axes Global r 2 Create point 1 by K 0 00000 clicking on the button 1 Introduce i Apply or by pressing the coordinates z 0 00000 OO nter on the of point 1 Create new point sk Cha kevboard and Return Apply Close And create point 2 in the same way introducing its coordinates in the Coordinates Window amp The last step in the creation of the points as well as any other command is to press Escape either via the Escape button on the keyboard or by pressing the central mouse button Select Close to close the Coordinates Window Now we will create the line that joins the two points Choose from the Top Menu Geometry Create Straight line Option in the Toolbar shown below can also be used N Next the origin point of the line must be defined In the Mouse Menu opened by clicking the v right mouse button select Contextual gt Join C a 26 INITIATION TO GID Tg NOTE With option Join a point already created can be selected on the screen The command No Join is used to create a new point that has the coordinates of the point that is selected on the screen We can see that the cursor changes form for the Join and No Join commands Cursor during use of Join command Cursor during use of No Join command Now choose on the screen the first point and then the seco
149. wo parts of the model have been drawn Now they must be joined so that the final volume may be created and a mesh of the volume may be generated 5 1 Importing a GiD file 1 Choose Read from the Files menu Select the file where the first part created in section 3 was saved Click Open 2 Choose Files gt Import gt Insert GiD geometry from the menu Select the file where the second part created in section 4 was saved Click Open 3 The T junction appears Bear in mind that the lines which define the end of the first pipe background of the T junction and which have been imported were already present in the first file Notice that the lines overlap This overlapping will be remedied by collapsing the lines 4 Choose the option Geometry gt Edit gt Collapse Lines Select the overlapping lines and press ESC Figure 28 Importing the T junction file to the main file Some points are duplicated and must be collapsed GID USER MANUAL 93 5 2 Creating the final volume 1 Choose Geometry gt Create gt Volume gt By contour and select all the surfaces that define the volume Press ESC to conclude the selection process 2 Choose Render gt Smooth to visualize a more realistic version of the model Figure 29 A rendering of the finished piece of equipment CASE STUDY 2 6 GENERATING THE MESH Now that the model is finished it is ready to be meshed The mesh will be generated using Chordal Error in order to achieve greater accu
150. ypes of commands It is important to note that these options will differ depending on the whether the user is performing a preprocessing or postprocessing analysis and that the options needed in each case differ as well Two possible configurations of the Top Menu are presented below Gib Project UNNAMED Files View Geometry Utilities Data Mesh Calculate Help And in the postprocessing phase Gib Project UNNAMED Files View Utilities Do cuts View results Options Window Help These two options will be presented in more detail later Next each drop down menu in the Top Menu will be described in detail 4 PRESENTATION OF GID Files Two main types of functions can be controlled in this menu 1 the handling of files i e create read save etc of GiD projects and 2 the importing and exporting of files Creates a new project Reads a previously created GiD project les Saves to disc all information related Fies to the project Ps New Ctr s Ctrl ri Open ee Import files Saves information lt 4 Save Ctrl with name chosen by 7 Save ag Ctrl x Ctrl s IGES Chri the user Ck a ae DXF Ctrl d l l Import Farasolid Changes the configuration for ACIS postprocess phase Export YDA Rhino lt gt Postprocess Shapefie Ei b NASTRAN mesh Saves the drawing p ee STL mesh image shown on the Pageimage setup YAML mesh screen in one of the G Print 3D Studia mesh following f

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