Meshing of 2-D Cross Section Mesh Tool Comparison

1. Meshing of 2-D Cross Section Mesh Tool Comparison Group: Graden Hardy, Patrick Lewis Date: 22 April 2009 ME 501 – Design of Mechanical Structures Department of Mechanical Engineering

2. Outline • Problem Description • Model Description • Results • Free Mesh – Default • Free Mesh – Smart Size • Free Mesh – Size Control:Global • Free Mesh – Q-Morph Mesher • Mapped Mesh – Regions • Discussion • Automatic Vs. Mapped • “Mesh Tool” • “Mesher Opts” Department of Mechanical Engineering

3. Problem Description • Develop a cross section that would require the use of advanced mesh generation tools • Provide a comparison of the different mesh tools that are available • Visually inspect the resulting element shapes and sizes Department of Mechanical Engineering

4. Model Description • Geometry • Solid CAD model created • CAD Drawing developed for modeling in ANSYS • Element Type • 2-D Plane Stress Element • Plane 82 (Solid  Quad  8node – 82) Department of Mechanical Engineering

5. Results • Meshing Tools: • Free Mesh • Mapped Mesh • Tool Options Explored • Free Mesh • Default • Smart Size • Size Control:Global • Q-Morph Mesher • Mapped Mesh • Regions Department of Mechanical Engineering

6. Free Mesh – Default • Tool Description: • No constraints on element patterns • No constraints on element shapes • Capable of meshing irregular shapes • Element Plots: • Inability to control the element generation results in badly shaped elements • Meshing Error – Element Checker • Angle between two adjoining sides of an element can be no greater than 165° • For highlighted element the angle is 167.3° Department of Mechanical Engineering

7. Free Mesh – Smart Size • Tool Description: • Creates initial element sizes for free meshing operations • Better chance of creating reasonably shaped elements • Algorithm computes an estimated element edge length for all lines in the area/volume being meshed • Edge lengths are further refined to account for curvature and proximity of surrounding features in the geometry • User must specify a mesh size level • 1 (fine mesh) • 10 (coarse mesh) Department of Mechanical Engineering

8. Free Mesh – Smart Size Cont. • Free Mesh Element Plot w/Smart Size Level 4 Department of Mechanical Engineering

9. Free Mesh – Smart Size Cont. • Free Mesh Element Plot w/Smart Size Level 5 Department of Mechanical Engineering

10. Free Mesh – Size Control:Global • Tool Description: • Mandates the size of the elements to a default size set by the user • Requires knowledge and experimentation by the user to come to a suitable final element size • Element Plot: • Provided a good mesh w/no triangular elements • Created several transition elements Department of Mechanical Engineering

11. Free Mesh – Q-Morph Mesher • Tool Description: • This mesher generally provides higher quality quadrilateral elements than the alternative and is very effective with boundary sensitive geometries • Meshing options must be carefully adjusted to eliminate triangular elements • Smart Size feature must be enabled • Global element size provision also provides a better mesh Department of Mechanical Engineering

12. Free Mesh – Q-Morph Mesher Cont. Preprocessor  Meshing Mesher Opts  Triangle Mesher Alternate Quad Mesher Main Split poor quality quads  Off Department of Mechanical Engineering

13. Free Mesh – Q-Morph Mesher Cont. Video Department of Mechanical Engineering

14. Free Mesh – Q-Morph Mesher Cont. • Element Plot: • Provides a decent mesh • No triangular elements • Few oddly shaped transition elements • Reasonable Pattern Department of Mechanical Engineering

15. Mapped Mesh – Regions • Tool Description: • Constraints placed on element patterns and shapes • Only works with basic geometries • Irregular geometries must be broken down into basic regular regions • User has the option of choosing between quadrilateral or triangular elements Department of Mechanical Engineering

16. Mapped Mesh – Regions Cont. • Video Department of Mechanical Engineering

17. Mapped Mesh – Regions Cont. • Regions Plot: • Area was broken into basic 3-5 sided regions Department of Mechanical Engineering

18. Mapped Mesh – Regions Cont. • Element Plot: • Provided nicely shaped and patterned elements Department of Mechanical Engineering

19. Discussion • Automatic Vs. Mapped Meshing • Automatic meshing functions have good capabilities for meshing difficult geometries, but are limited in their abilities to provide uniform element shapes and patterns. • Mapped meshing tools, although tedious in use, are more powerful and controllable meshing tools Department of Mechanical Engineering

20. Discussion Cont. • “Mesh Tool” • Most efficient tool available for rapid mesh creation/control • Toolbar combines most of the other mesh tool menus to allow the user to quickly navigate between different mesh tool settings and options. • This tool bar is activated by selecting: • Preprocessor  Meshing  Mesh Tool Department of Mechanical Engineering

21. Discussion Cont. • “Mesher Opts” • Powerful tool found within the meshing menu • Toolbar allows for more advanced control of the meshing functions • This tool bar is activated by selecting: • Preprocessor  Meshing Mesher Opts Department of Mechanical Engineering

22. Questions? Department of Mechanical Engineering