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Meshing of 2-D Cross SectionMesh Tool Comparison

Group: Graden Hardy, Patrick LewisDate: 22 April 2009

ME 501 – Design of Mechanical Structures

Outline

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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”

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

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Model Description

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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)

Results

Meshing Tools: Free Mesh Mapped Mesh

Tool Options Explored Free Mesh

Default Smart Size Size Control:Global Q-Morph Mesher

Mapped Mesh Regions

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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°

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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)

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Free Mesh – Smart Size Cont.

Free Mesh Element Plot w/Smart Size Level 4

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Free Mesh – Smart Size Cont.

Free Mesh Element Plot w/Smart Size Level 5

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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 elementsDepartment of Mechanical

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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

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Free Mesh – Q-Morph Mesher Cont.

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Preprocessor Meshing Mesher Opts Triangle Mesher Alternate Quad Mesher MainSplit poor quality quads Off

Free Mesh – Q-Morph Mesher Cont.

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Video

Free Mesh – Q-Morph Mesher Cont.

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Element Plot: Provides a

decent mesh No triangular

elements Few oddly

shaped transition elements

Reasonable Pattern

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

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Mapped Mesh – Regions Cont.

Video

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Mapped Mesh – Regions Cont.

Regions Plot: Area was broken into basic 3-5 sided regions

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Mapped Mesh – Regions Cont.

Element Plot: Provided nicely shaped and patterned

elements

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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

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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 ToolDepartment of Mechanical

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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

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Questions?

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