说明案例msc.patran courses课程

1、WORKSHOP 8VARIOUS METHODS OF SOLID MESHING Workshop Objectives e familiar with creating a Hex and a Tet mesh. For this workshop, four models of the same system - a Hex8, a Hex20, a Tet4, and a Tet10 element model are to be created. This involves creating geometry from which the meshes are created. T

2、he same constraints and applied loading are used for each model. The results from a linear static analysis of each model are compared.Problem DescriptionDetermine the deformation and stress for models that have different types of solid elements, i.e. Hex8, Tet4.Lug model material: Aluminum with E =

3、10 x 106 psi and n = 0.3Pressure on lug model is spatially dependentSoftware VersionPatran 2008r1MSC Nastran 2008r1Key Concepts and Steps:Database: create a new database with Analysis Code = MSC.Nastran and Analysis Type = StructuralGeometry: import Parasolid solid geometry model of lug from a file

4、Geometry: create four geometric models; two for Hex mesh, and two for Tet meshGeometry: create a cylindrical coordinate system for each modelElements: either Hex mesh or Tet mesh a geometric solid, so that two Hex meshes and two Tet meshes are createdFields: create a field, to be used for applied pr

5、essure creation, for each modelLoads/BCs: create applied pressure loading and constraints for each modelMaterials: specify an isotropic material for AluminumProperties: create a 3D solid propertyAnalysis: Solution Type = Nastran Linear Static, Solution Sequence = 101, Method = Full RunAnalysis: acce

6、ss analysis results by attaching the XDB file to databaseResults: plot von Mises stress and displacement results for each modelResults: compare results for the different modelsStep 1. Create New Database for 3D LugCreate a new database called lug.db and set the model preferences:File / NewEnter lug

7、as the file name.Click OK.Set Tolerance to Based on Model.Enter 10.0 for the Model DimensionSet the Analysis Code and Analysis Type to MSC.Nastran and Structural, respectively.Click OK.abcdefgStep 2. Import the Parasolid .xmt FileImport a Parasolid solid and change views:File / ImportObject: Model S

8、ource: Parasolid xmtSelect lug.xmt and click Apply.Click OK.Click Iso 1 View icon.bacdceStep 2. Import the Parasolid .xmt File (Cont.)Step 3. Rename the default_group Rename the group default_group:Group / ModifyClick Rename.Select default_group and Rename As: hex8Click OK.Click OK.accdbeStep 4. Cre

9、ate Points for Plane CreationCreate points that will be used later to create several breaking planes:Geometry: Create / Point / ExtractMake sure the Parametric Position is set to 0.5.Uncheck: Auto Execute.Click under Curve List and Shift-click three edges: the two edges that make up the outer radius

10、 of the solid, and one of the back edges.Click Apply.Increase point size by clicking the Point size icon.acbdfedStep 5. Create the First Two PlanesacbbbccCreate two planes that will be used for breaking the solid:Geometry : Create / Plane / 3 PointsClick under Point 1 List. Select the first point fo

11、r the first plane. Then, select the other two points. Note, with Auto Execute on, the mouse focus changes to the next line automatically.Select next 3 points to create the second plane.Step 6. Break SolidBreak the solid using the newly created planes:Geometry : Edit / Solid / BreakOption : PlaneTurn

12、 Auto Execute off. Select the Lug, Solid 1, for Solid List, and Plane 2 for Break Plane List.Click Apply.Click Yes when message appears.Shift-click the lower and upper solids (Solid 2 and 3) for Solid List, and Plane 1 for Break Plane List.Repeat steps e and f using Plane 1 as the breaking plane.Cli

13、ck Refresh graphics icon.ePlane 2Plane 1bacdfdgigStep 7. Create Group tet4, and Copy Geometry into itCreate group tet4, and translate(copy) the newly created solidsinto it, posting both models:Group / CreateEnter tet4 under New Group Name.Click Apply, then Cancel.Geometry : Transform / Solid / Trans

14、lateEnter for Direction Vector.Uncheck Auto Execute. Select all four solids for Solid List by dragging a box around the lug, and click Apply.abcdefgGroup : hex8Group : tet4Step 8. Create Group tet10, and Copy Geometry into itCreate group tet10, and translate the solids into it:Group / CreateEnter te

15、t10 for New Group Name.Click Apply, and Cancel. Geometry : Transform / Solid / TranslateEnter for Direction Vector. Select the same four solids.Click Apply.abcdegfGroup : hex8Group : tet4fStep 9. Showing the Geometry for Three GroupsClick Front View.aGroup : hex8Group : tet4Group : tet10Step 10. Pos

16、t Only Group hex8 Post just group hex8 to facilitate creation of the solids needed for creation of hex elements (to use IsoMesh):Group / PostSelect group hex8.Click Apply, then Cancel.Change the view using the icon Iso 1 View.Click Fit view icon.aedcbGroup : hex8Step 11. Create More Points for Break

17、ing PlanesCreate 5 points that will be used to create several planes:Geometry : Create / Point / ExtractMake sure Parametric Position is set to 0.5.For Curve List, shift select 5 edges: four edges that make up the lower half of the lug-hole, and an edge at the base of the solid.Click Apply.acbcdcSte

18、p 11. Create More Points for Breaking Planes (Cont.)Create points at the center of the hole of the Lug:Geometry : Create / Point / ArcCenterUncheck: Auto Execute.Shift select the two edges that make up the hole of the lug.Click Apply.acbdbcStep 12. Create More Breaking PlanesCreate two more planes t

19、hat will be used to break the solids. With Auto Execute on, the planes will automatically be created once all three points are chosen:Geometry : Create / Plane / 3 PointsFor the Point 1 2 and 3 List, select the three points defined for b in the figure.For the Point 1 2 and 3 List for the next plane,

20、 select the three points defined for c in the figure.abcStep 13. Break Solids Break the solids again, thistime using the newly createdPlanes:Geometry : Edit / Solid / BreakFor the Solid and Break Plane List select the bottom left portion of the solid and the break plane shown in the figure, respecti

21、vely. Click Apply.Click Yes when message appears.Click Refresh graphics icon.For the next plane select the bottom right portion of solid and the break plane shown in the figure.Repeat Steps c, d, and e.acbdbeffStep 14. Create Final Point and Plane.Now create the last point that will be used to creat

22、e one moreplane:Geometry : Create / Point / ProjectUncheck: Auto Execute.For Point List, select the point at the bottom end of the sloped edge where it intersects with the base.For Curve List, select edge normal to the hole.Click Apply.Geometry : Create / Plane / 3 PointsUncheck: Auto Execute.For Po

23、int 1 2 & 3 List: select two points along the base of the solid and the newly projected point.Click Apply.accbihdefghdStep 15. Break SolidBreak a solid one final time using the recently created plane:Geometry : Edit / Solid / BreakOption : PlaneUncheck: Auto Execute.For Solid List: select solid at b

24、ottom-right, Solid 19.For Break Plane List: select Plane 5.Click Apply.Click Yes when message appears.Click Refresh graphics icon. aedbcdfeghStep 16. Delete Solids and PlanesDelete the two top solids, as they are not to be used for IsoMesh meshing. Delete the five planes, as they are no longer neede

25、d. Reduce the size of the point circle markers.Geometry : Delete / SolidShift select the two top solids as shown in the figure.Click Apply.Refresh graphics.Geometry : Delete / PlaneSelect all five planes, Plane 1:5.Click Apply and refresh graphics again.Decrease the size of the point markers by clic

26、king the Point size icon.acefbbdgdStep 17. Refit SolidsRefit the five solids so that they e parametric (blue) solids. They can be IsoMesh.Geometry : Edit / Solid / RefitOption: To TriCubicNetEnter 1 for all of the Refit Parameters.Check: Delete Original Solids.Select the five solids.Click Yes when f

27、irst message appears, and Yes for All when second message appears.Show the Labels toolbarDisplay the Solid labels.Un-display Labels toolbar.acebdhgeffiStep 17. Refit Solids(Cont.)Step 18. Mirror SolidsFinish creating all thegeometry by mirroring the fiveparametric solids, producing acomplete paramet

28、ric model:Increase the size of the point markers.Geometry : Transform / Solid / MirrorFor Define Mirror Plane Normal: Click the 3 points for the plane icon and then shift select any 3 points that lie in the plane in the figure.Check: Reverse Solid.Select all the solids, Solid 22:26.eShift select any

29、 3 points that lie within this plane. This plane will serve as the mirror plane.bcadccStep 19. Create Group Hex20, and Copy Geometry into itCreate the group hex20, and translate the Geometry:Group : CreateEnter hex20 for New Group Name.Click Apply and Cancel. Geometry : Transform / Solid / Translate

30、Enter for Direction Vector.Uncheck: Auto Execute.Solid List: Select all ten solids, and click Apply.acbedfggGroup : hex8Group : hex20Step 20. Showing the Geometry for all Four GroupsPost all groups:Group : PostClick Select All.Click Apply, then Cancel.Specify Front view.Click the Fit view icon.Reduc

31、e size of point markers.Show the Labels toolbar.Un-display Solid labels.Un-display Labels toolbar.adefghbciGroup : hex8Group : hex20Group : tet4Group : tet10Step 21. Create a Coordinate SystemCreate a cylindrical coordinate system for the hex8 model. This coordinate frame will later be used to apply

32、 a radial pressure. This coordinate frame will later be translated to the other three models.Click Iso 1 View icon and Point size icon.Zoom into the hex8 model using View corners icon.Geometry : Create / Coord / 3PointType : CylindricalSelect 3 points (as indicated).Point on Plane 1-3OriginPoint on

33、Axis 3This is how the coordinate system should look like for the hex8 model.bacdeaStep 22. IsoMesh Groups Hex8 and Hex20Mesh solids for the hex8 and hex 20 groups using IsoMesh: Group : PostSelect only the hex8 group.Click Apply, then Cancel.Elements : Create / Mesh / SolidSelect Hex, IsoMesh, and H

34、ex8.Uncheck: Automatic Calculation. and enter 0.5 for Global Edge Length.For Solid List: Select the hex8 geometryClick Apply.Repeat steps a through h, posting the hex20 group, selecting Hex20 instead of Hex8 for the Topology, and applying it to the hex20 geometry. It may be necessary to click the Re

35、fresh graphics and the Fit view icons when switching from group to group.abcghdefStep 22. IsoMesh Groups Hex8 and Hex20 (Cont.)Note the difference between the hex8 and hex20 meshes, namely, the midsize nodes.aPost the hex8 and hex 20 group: Group : PostSelect the hex8 and hex20 group.Click Apply, th

36、en Cancel.Click the Fit View icon.Click the Node size icon. dbceStep 23. TetMesh Groups Tet4 and Tet10Now, create the final two meshes for the remaining models. This time, the TetMeshwill be utilized. Group : PostSelect the tet4 group.Click Apply, then Cancel.Elements : Create / Mesh / SolidSelect T

37、et, TetMesh, and Tet4.For Input List: select the tet4 geometry.Uncheck: Automatic Calculation. Enter 0.5 for Global Edge Length.Click on Assembly Parameters and check the Match Parasolid Faces.Click Close.Click Apply.Repeat steps a through k, posting the tet10 group, selecting Tet10 for the Topology

38、 instead of Tet4, and applying it to the tet10 geometry.Click the Node size icon.Note the absence or presence of midside nodes.gihhjdeflStep 24. Observe Element Free Edges of Meshed SolidsPost all four groups and observe the element free edges:Group : PostSelect all four groups.Click Apply, then Can

39、cel.Elements : Verify / Element / BoundariesClick Apply (observe the free element edges of meshes. This can be easily remedied by equivalencing the meshes).Elements : Equivalence / All / Tolerance CubeClick Apply.Elements : Verify / Element / BoundariesClick Apply.The yellow lines indicate the eleme

40、nt free edges. Here, the elements are not connected.After equivalencing, the elements are connected and the only yellow lines are for the desired free edges.It is not necessary to post each group and equivalence each model. The equivalence “All” action is applied to all 4 models.egdfhiStep 25. Copy

41、Coordinate SystemIn order to create the loads and boundary conditions, the cylindrical coordinate system for the hex8 model must be translated to the remaining models:Geometry : Transform / Coord / TranslateEnter for Direction Vector.Select Coord 1 for Coordinate Frame List.Repeat steps a through c

42、to create Coord 3 using for Direction Vector, and select Coord 1 for Coordinate Frame List.Repeat steps a through c to create Coord 4 using for Direction Vector, and Coord 2 for Coordinate Frame List.acbStep 26. Create Fields for Loads/BCsCreate a field for each pressure loading:Click on the Smooth

43、Shaded icon.Fields : Create / Spatial / PCL FunctionEnter sin_pressure_hex8 for Field Name.Select Coord 1 for Coordinate System.Enter sinr(T) for Scalar Function, and click Apply.Create 3 more fields by following steps c through e. Refer to the table below for the corresponding field names and coord

44、inate frames. Field NameCoordinate Systemsin_pressure_hex8Coord 1sin_pressure_hex20Coord 2sin_pressure_tet4Coord 3sin_pressure_tet10Coord 4There should be four different fields, and each field name should reference a corresponding coordinate frame (i.e. there should be one field per model). When cre

45、ating the fields, it is not necessary to post each group separately.cbdfaeStep 27. Create Loads and Boundary ConditionsCreate four pressures, one foreach model, using the createdfields:Loads/BCs : Create / Pressure / Element UniformEnter hex8 for New Set Name.Click on Input DataEnter 1000 under Load

46、/BC Set Scale Factor.For Pressure, select sin_pressure_hex8 from Spatial Fields. Click OK.acebdfStep 27. Create Loads and Boundary Conditions (Cont.)For the hex 8 model, specify the application region for the pressure: Click on Select Application Region.For Select Solid Faces, shift-click the four f

47、aces (as indicated), and click Add.Click OK.Click Apply.Select these four faces for the application region for the hex8 pressure.bacdbbStep 27. Create Loads and Boundary Conditions (Cont.)Pressure NameSpatial Fieldhex8sin_pressure_hex8 hex20sin_pressure_hex20tet4sin_pressure_tet4tet10sin_pressure_te

48、t10These are two typical faces where the pressures for the tet4 and tet10 models should be applied.Repeat the previous steps for the remaining three pressures, zooming in on each model as needed. Included is a table of the pressure names and the corresponding spatial fields. After all four pressures

49、 are created, click the Fit view icon to show all the models. The viewport should be similar to the illustration below. Make sure that the pressures at /2 are 1000 for each model.These are four typical faces where the pressures for the hex8 and hex20 models should be applied.Group : hex8Group : hex2

50、0Group : tet4Group : tet10Step 27. Create Loads and Boundary Conditions (Cont.)Create constraints on each modelwith just one constraint set:Loads/BCs : Create / Displacement / NodalEnter constraint for New Set Name.Click Input DataEnter for Translations only.Click OK.Click Select Application RegionC

51、lick the Surface or Face icon.For Select Geometry Entities: shift select the back faces of all the models (see next page), click Add, then OK.Click Apply.bacdefghhhiStep 27. Create Loads and Boundary Conditions (Cont.)hhhhStep 28. Create Material and Element PropertiesCreate the material properties

52、for the models:Materials : Create / Isotropic / Manual InputEnter Aluminum for Material Name.Click Input PropertiesEnter 10E6 and 0.3 for the Elastic Modulus and Poisson Ratio, respectively.Click OK.Click Apply.acebdfStep 28. Create Material and Element Properties (Cont.)Create the element propertie

53、s using one property set:Properties : Create / 3D / SolidEnter Solid for Property Set Name.Click Input PropertiesClick on Mat Prop Name icon and select Aluminum.Click OK.acebddStep 28. Create Material and Element Properties (Cont.)Click Select Application Region.For Select Members: select all solids

54、, and click Add.Click OK.Click Apply.ghifgStep 29. Check the Load CaseCheck the load case Default to ensure that all the pressure loads and the constraint have been included:Load Cases : ModifyClick on load case name Default.Make sure all the loads and constraints are listed, then click Cancel. Even

55、 though there are four disjoint (unrelated) models in this database, Patran views them as one model. Nastran will solve the models as one model as long as each model is correctly defined.acbStep 30. Run AnalysisRun the analysis by submitting the model to MSC Nastran:Analysis : Analyze / Entire Model

56、 / Full RunClick Solution TypeMake sure LINEAR STATIC is selected.Click Solution ParametersClick Results Output FormatMake sure XDB and Print are selected.Click OK.Click OK.Click OK.Click Apply.abcegdfhijStep 31. Read and Display Analysis ResultsRead and compare the results forthe four models. First

57、, attach theXDB file.Analysis : Access Results / Attach XDB / Result EntitiesClick Select Results FileSelect lug.xdb and click OK.Click Apply.acbcdStep 31. Read and Display Analysis Results (Cont.)Create a deformation plot of all four models. It will be difficult to see the deformation with the unde

58、formed shape and geometry posted. So, unpost both.Results : Create / DeformationSelect Displacements, Transitional and click Apply.Click on the Display Attibutes icon.Remove check from Show Undeformed and Show Title and click Apply.Click on Plot/Erase icon.Click Erase under Geometry, and click OK.ab

59、dfbcdefStep 31. Read and Display Analysis Results (Cont.)Step 31. Read and Display Analysis Results (Cont.)Plot the von Mises stress foreach of the models: Results : Create / FringeSelect Stress Tensor, and von Mises.Click Apply.acbbStep 31. Read and Display Analysis Results (Cont.)Here is the deformed shape plotted with the von Mises stress. Note that it is somewhat difficult making comparisons between the models becaus