PATRAN中如何修补模型间隙.ppt

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1、WS8-2PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationWorkshop 8 Surface Mesh For Noncongruent SurfacesWS8-3PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationnObjectivesuImport geometric surfaces from a MSC.Patran neutral file.uObserve the many gaps

2、 between adjacent surface edges.uMesh the surfaces with tria elements, then connect elements where there are internal free element edges.uCreate a geometric surface from the tria mesh.uMesh the new surface.Workshop 8 Surface Mesh For Noncongruent SurfacesWS8-4PAT301AERO, Workshop 8, October 2004Copy

3、right 2004 MSC.Software CorporationnProblem DescriptionuTo create a finite element model for several geometric components (for this case multiple surfaces; see below) it is necessary to connect adjacent elements (e.g. Equivalence) at geometric interfaces. When there are gaps (larger than the toleran

4、ce (*), or difference of vertices (*) at interfaces it is more difficult to connect the elements. One way to deal with this is to create a triangular (tria) element mesh for each of the geometric entities, “sew” (equivalence) the regions where there are no elements, then create a single geometric su

5、rface from all the tria elements. Finally, delete the tria element mesh, and create a 2-D mesh (e.g. Quad4) by meshing the single surface obtained from the tria element mesh.*Workshop 8 Surface Mesh For Noncongruent SurfacesWS8-5PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software Corpora

6、tionnSuggested Exercise Stepsu Create a Database.u Import a MSC.Patran neutral file with surfaces.u Show the distance between two points.u Create 2-D mesh.u Close gaps between adjacent tria elements.u Look at element free edge boundaries. u Delete original geometry and create new surface.u Mesh new

7、surface.Workshop 8 Surface Mesh For Noncongruent SurfacesWS8-6PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationStep 1. Create a DatabaseCreate a new database named shell.n File / New.n Enter shell as the file name.n Click OK.n Select Default under tolerance.n Select MSC.Nas

8、tran as Analysis Code.n Select Structural as Analysis Type.n Click OK. abdcfegWS8-7PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationStep 2. Import a MSC.Patran Neutral File With SurfacesImport the neutral file called shell_prt.out.1.n File / Import. n Select Neutral as Sour

9、ce.n Locate the file named non_cong_surfs.out.n Click Apply. n Click Yes.n Click Yes. abcdefWS8-8PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationThis is what the imported surfaces should look like. Look at the gapsStep 2. Import an MSC.Patran Neutral File With Surfaces (Co

10、nt.)WS8-9PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationStep 3. Show the Distance Between two Points Determine the distance between two adjacent points. This will help in the determination of the value of the global edge length for subsequent Paver meshing.n Geometry: Sho

11、w / Point / Distance.n Select Point 231 under First Point List.n Select Point 370 under Second Point List. a. Click Apply. accbbdWS8-10PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationStep 4. Create 2-D Mesh Create 2-D mesh using Paver for set of surfaces. n Elements: Creat

12、e / Mesh / Surface. n Select Tria, Paver, and Tria3.n Uncheck Automatic Calculation.n Enter 2.0 as Global Edge Length. n Select all surfaces for Surface List.1. Click Apply.abcdefWS8-11PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationStep 5. Close Gaps Between Adjacent Tria

13、 ElementsClose the gaps in the model by “sewing” themesh together.The “Sew” command issimilar to Equivalence.n Elements: Modify / Mesh / Sew.n Enter 6.0 as Target Element Edge Length.n Click on Tria Element List and select all elements.1. Click Apply.abcdWS8-12PAT301AERO, Workshop 8, October 2004Cop

14、yright 2004 MSC.Software CorporationShow where the element freeedges aren Elements: Verify / Element / Boundariesn Select Free Edges as Display Type.1. Click Apply.Step 6. Look at Element Free Edge Boundaries abcWS8-13PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationStep 7.

15、 Delete Original Geometry and Create New SurfaceDelete the original geometry for visual clarity, and create a surface from the existing 2-D tria mesh with a gap/hole.n Geometry: Delete / Surface.n Click on Surface List and select all surfaces.n Click Apply. n Geometry: Create / Surface / Mesh. n Che

16、ck Delete Original Elements.n Click on Elements List and select all elements.n Choose None for Inner Loop Options.n Choose Fast for Surface Creation Methods.a. Click Apply.abcdefghiWS8-14PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationThis is what the new surface should lo

17、ok like.Step 7. Delete Original Geometry and Create New Surface (Cont.)WS8-15PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationStep 8. Mesh New Surface Mesh the surface just created using Quad4 elements. n Elements: Create / Mesh / Surface. n Select Quad, Paver, and Quad4.n Uncheck Automatic Calculation.n Enter 6.0 as Global Edge Length. n Select the new surface for Surface List.1. Click Apply.abcdefWS8-16PAT301AERO, Workshop 8, October 2004Copyright 2004 MSC.Software CorporationStep 8. Mesh New Surface (Cont.)Close database. 1. File / Close.