Geometry Abstraction Section Meshing

1. Geometry Abstraction & Section Meshing

2. Geometric Abstraction and Meshing

3. Quickly pass through the model construction phase Engineering begins after the results are available Geometry Effects

4. A Break-Down of the CAE Process What is the most time consuming process?

5. Direction of SDRC�s CAE Much Focus on Pre-Processing Automatic & Robust Tool for building FE Model

6. Improvements during MS5 - MS7 Some examples of the reduction time to build FE Model

7. Powerful Geometry Abstraction Part contains 300 surfaces. Abstracted to 24 meshing regions

8. Customer Endorsements ZF Automotive supplier to many major OEM�s of Driveline and chassis technology Complex parts/assemblies (I.e. transmission cases) �Almost 30% development time saved by using I-DEAS Section Meshing Technology� Dr. Kelkel ZF, Germany

9. Typical Design Geometry Topology Issues small edges compound edges sliver surfaces high aspect ratio missing surfaces topology too detailed reconstruction

10. Small Edges Force small element edges Causes high distortions for elements larger than edge Dictates element size

11. Sliver Surfaces Narrow surface which causes distortions and stretched elements

12. Disconnected Surfaces Surfaces which are not �stitched� together do not share the same edges Causes discontinuous mesh that do not allow forces to transfer across the discontinuity

13. Poorly Parameterized Surfaces Surfaces which do not have evenly spaced iso lines do not have evenly spaced parameter space in 3D Results in skewed and stretched elements Especially in imported geometry

14. Meshing algorithms Bounded by surface shape and boundaries can distort elements beyond usefulness dictates element size

15. Section Meshing Expands the boundaries of surfaces relaxes mesh area therefore improving quality of elements removes boundary and shape constraints that negatively effects meshing

16. Section Meshing Permits edge connectors to be removed Removes requirement of having at least one element/edge Relaxes elements and therefore improves mesh quality

17. Too Much Detail Small holes usually have adverse effect on mesh increases number of nodes/elements in unimportant area of model can distort elements because of local curvature but are internal boundaries which meshing algorithms must address

18. Too Much Detail Often only one single node is needed to represent hole for boundary condition definition model more efficient

19. Too Much Detail Topology Suppression History Supported requires integrated modeler Automatic / Manual Modes Loop Collapsed to Point Curve Collapsed to Point Ignores Small Edges

20. Solid Meshes Section meshing applies to solids also Sections can be used to map mesh volumes for brick elements generation

21. Section Meshing Capture Analysis Intent User Control Puts the model size (degrees of freedom) within the control of the user Does not change the geometry (surfaces, edges, . ) of the part Overhead minimal because no additional geometry is created all nodes are on original surfaces and elements can span surface boundaries Integrity of part is intact

22. Where do I start? I know I can abstract my model but with complex models How do I find the problem areas? What element size should I use? How much time should I spend abstracting?

23. Where Do I Start? Real Parts Automatically combine surfaces until user criteria is met

24. Surface and Section Quality Checks The meshing job is a balance of FEM size (element size) and how much interaction the user wants to go through to get the element size he wants In the past modeling time was unpredictable because it was impossible to anticipate how many of these problem situations would arise

25. Quality Check Find small edges Find sliver surfaces Find small holes Show me expendable connectors

26. Quality Checks Highlight problem geometry

27. Quality Checks How many bad surfaces do I have? Indicates how much work I have to do to make useable mesh based on criteria if not many I know what element size this geometry will take if checks are made on sections, then same indications are available and user knows how much work is left Continue until all sections disappear

28. Section Mesh Layout

29. Approach Natural operation - editing the wireframe - interactive Add / Remove / Replace Loops Curves Connectors Build sections on all surfaces Addressed isthmus, sliver topology UI consistency Additional Functionality Robust auto create Extended loop modification commands

30. I-DEAS 8 - Procedure New Auto create Intelligent methods deployed to generate desired sections User controlled Conservative section generation 95% of generated section are meshable Wireframe edits Easy modification of the sections once all are defined Consistent UI (Add / Remove / Replace) Sections will rebuild after modifications without being deleted Full Process supported Other commands that enable the overall process Meshability check (Enhancement of existing check) New Manual element tools to correct resulting mesh Surface Patch Generation

31. Performance Increased performance of sections generate on large models Wireframe edits are interactive regardless of model size New Auto create yields a base set of sections that are usable User now in a modify mode Highlights the strength and performance of the edit commands Extendable for better section generation For multi-surfaced sections use Meshability Check to verify limitations are not violated Feedback indicates where problem may be if check fails

32. Workflow Workflow Auto Generate Sections Perform meshability check Perform section check Perform section free curve check Evaluate abstraction Wireframe Edits Target areas that need additional abstraction or modification for meshability Interactive commands allow user to quickly complete the abstraction Perform meshability checks as the user edits the sections Mesh sections Apply geometry based boundary conditions AFTER section meshing

33. Results

34. Results

35. Results

36. MS8 Replace Curve

37. Replace Curve

38. Replace Curve

39. Mid-Surface Challenges for Section Mesh

40. Section Add Curve

41. Gap too large for auto section to close

42. Project surface boundary and replace

43. Quality Checks All geometric problems anticipated Meshing reduced to one iteration in most cases

44. Meshing Issues - Tet Hex Tet Hex meshing allow mixing of Parabolic Tets with Bricks Multipoint Constraint elements (MPCs) tie up loose mid nodes

45. Meshing Issues - Manual Control

46. Meshing Issues - Manual Control

47. Meshing Issues Element Collapse (under the Quality Checks icon stack) Collapse narrow (stretched) linear or parabolic triangular shells

48. Mesh Generations Brick Elements from shell projection

49. Mesh Generation Project Elements to Surface

50. Augmentation of Geometry Geometric information; physical representation Additional structure. Calculation surface to measure energy propagation. Contact regions, FEM or geometry based. Weld attachments, reference series of locations Non-geometric information; non-physical representation interpolated surfaces. lumped masses, springs, or beams. gaps, coupled dofs, or constraint equations.

51. Adaptation of the FEM Associative to design definition geometry change abstraction change boundary conditions loading conditions surface mapping Surface mapping/compare parts domestic/imported

52. Mesh Generation Many new options and features for mesh construction, including: Automatic tetrahedral to hexahedral interface Create Thickness Results Element Extrude Normal Element Project Element Collapse

53. Improve Elements� Quality Nodes Drag Viewing quality values Improve surface mesh quality Auto Settings during meshing Automatic Mesh Checking & Improvement Tetra Fix Move Mid Nodes + Straighten Edge Plump Fix Flat tet elements

54. Integrated CAE with 3D/CAD Surfaces Mapping Imported Geometry from other CAD

55. Surface Mapping Can foreign CAD geometry be Associative to FE data? What if the model is a mixture of foreign CAD surfaces and I-DEAS generated geometry complete with history?

56. Surface Mapping Section meshing used to define meshing regions

57. Surface Mapping New design introduced from packaging detail design work User can map new surfaces, edges, and surface normals into correct orientation for feature replacement

58. Surface Mapping Associativity reintroduced to the FEM from the mapping process Additional features beyond mapped geometry automatically maintained

59. Non-geometric Representation Midsurface Weld points usually modeled with rigid elements or couples Rigid bodies which I do not want to mesh usually modeled with lumped masses and rigid element issues about connections and associativity Connections to other components which transfer force but not infinitely stiff most conveniently modeled between two point with beams and possibly use of some rigid elements bolt connections Contacting surfaces between two bodies or portions of same part

60. Non-Geometric entities Rigid elements for U joint link Automated meshers need to recognize connection points between nodes on the hole and rigid element connections

61. Non-Geometric entities Spring elements and lumped masses need to be associative to the model which are meshed on modeled geometry

62. Non-Geometric Entities

63. Spot Weld Automatic meshing of entities without geometry

64. Non-Geometric entities Lumped mass for CG of connecting body Rigid element network for force distribution to center of mass

65. Summary Section meshing has become the preferred meshing approach to all model situations where shell and solid elements are automatically generated Geometry playing a more important role in FE efficiency for the CAE processes to have a more positive impact on the design to make it a reality to evaluate as many design alternatives automatically update the design from parameter studies and optimization activities

66. Future Development Further abstraction of outer boundary of section to remove narrow sliver areas without having to expand to neighboring surface Abstraction via feature recognition make a beam abstraction from 3D geometry (stiffeners) select surfaces software automatically creates cross section properties define connection information to rest of model Automatic multi-surface section definition based on element size selection Expand the element support to entire element library