Department of Mechanical Engineering 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 Engineering2  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”

 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 Engineering3

4  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)

 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 Engineering5

 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 Engineering6

 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 Engineering7

 Free Mesh Element Plot w/Smart Size Level 4 Department of Mechanical Engineering8

 Free Mesh Element Plot w/Smart Size Level 5 Department of Mechanical Engineering9

 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 Engineering10

 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 Engineering11

Department of Mechanical Engineering12 Preprocessor  Meshing  Mesher Opts  Triangle Mesher  Alternate Quad Mesher  Main Split poor quality quads  Off

Department of Mechanical Engineering13 Video

Department of Mechanical Engineering14  Element Plot:  Provides a decent mesh  No triangular elements  Few oddly shaped transition elements  Reasonable Pattern

 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 Engineering15

 Video Department of Mechanical Engineering16

 Regions Plot:  Area was broken into basic 3-5 sided regions Department of Mechanical Engineering17

 Element Plot:  Provided nicely shaped and patterned elements Department of Mechanical Engineering18

 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 Engineering19

 “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 Engineering20

 “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 Engineering21

Department of Mechanical Engineering22