© 2014 ANSYS, Inc. February 12, 2014 1 Release 15.0

Introduction to ANSYS Mechanical

15.0 Release

Workshop 4.2 Meshing Control

© 2014 ANSYS, Inc. February 12, 2014 2 Release 15.0

Goals Use the various ANSYS Mechanical mesh controls to enhance the mesh for the model below.

Problem statement:

• The model consists of a CAD file representing a solenoid.

• Our goal is to mesh the model using all defaults and inspect the result. Next we will add mesh controls to modify the mesh in various regions of the model.

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Assumptions

Since this is a meshing exercise we will not be applying loads or solving the model. Instead we will assume a linear static structural analysis is to follow the meshing operation.

Note, due to a certain randomness in the nature of meshing, the actual number of elements generated during the workshop may vary from machine to machine. This is normal.

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Project Schematic 1. In the Toolbox, double click “Static

Structural” to create a new analysis system.

2. RMB on the “Geometry” cell and “Import Geometry”. Browse to “Solenoid_Body.stp”.

3. Double click the “Model” cell to start the Mechanical application.

1.

2.

3.

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In Mechanical, specify US customary (in, lbm, lbf, °F, s, A, V)

Start by meshing the model using all defaults. This will establish a “base line” from which we can compare changes.

4. Highlight the mesh branch, “RMB > Generate Mesh”.

Basic Meshing

4.

When mesh generation

completes we can view the

mesh and inspect the

statistics in the details for the

mesh branch.

Note: node/element count

may vary slightly across

machines/platforms.

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Basic Meshing 5. View the mesh metrics:

a. Highlight the mesh branch.

b. In the details under “Statistics > Mesh Metric” specify “Element Quality”.

5a.

5b.

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Based on our inspection we may decide a more refined mesh is necessary for our analysis.

6. In the mesh branch details expand the “sizing” section and set the “Relevance Center” to “Medium.

7. RMB the mesh branch and Generate Mesh.

Mesh Size Control

The finer mesh is visually

obvious. The details show an

increase in the number of

elements as expected.

6.

7.

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Mesh Shape Control A closer look at the mesh shows some anomalies where certain faces meet.

By zooming to the area in question we can see several small “sliver” surfaces are forcing a fine mesh locally.

We’ll attempt to clean this up using virtual topology.

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8. Highlight the Model branch > RMB > Insert > Virtual Topology.

Since it appears that the sliver area is closer to being tangent to the sides, we will combine these into virtual cells.

Virtual Topology

Side

Sliver

In order to preserve the basic

topology we will join pairs of

surfaces into virtual cells rather

than trying to combine all surfaces

together. The result will be 3 cells

per side, 6 in total.

8.

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. . . Virtual Topology 9. Create Virtual Cells:

a. Select one of the sliver surfaces.

b. Hold the CTRL key and select the adjacent surface (as shown at right).

c. RMB > Insert > Virtual Cell.

The resulting virtual cell is displayed in red. Although underlying surfaces still exist, this is the surface the mesher will use.

9a. 9b.

9c.

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. . . Virtual Topology Continue by creating the remaining 5 virtual cells (select in pairs as before). When complete you will have a total of 6 virtual faces and 4 virtual edges.

Remesh the model:

10.Highlight the Mesh branch, RMB > Generate Mesh.

The resulting mesh shows

a much more uniform

mesh with a significant

reduction in element

count.

10.

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Mapped Face Meshing 11. Map mesh several faces (highlight Mesh

branch):

a. Select the 3 planar faces shown here.

b. RMB > Insert > Mapped Face Meshing.

c. RMB > Generate Mesh.

As shown map

meshing results is

elements on the

selected faces which

share very regular

shapes.

11c.

11b.

11a.

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Face Size Control 12. Specify face sizing on selected face:

a. Select the face of the gusset section shown here.

b. RMB > Insert > Sizing.

c. Set Element Size = 0.03.

d. Set Behavior = “Hard”. 13. Remesh the model (highlight the mesh branch):

• RMB > Generate Mesh.

12a.

12d.

12c.

12b.

13.

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Edge Size Control 14. Specify edge sizing on selected edges:

a. Select the 4 edges of the gusset shown here.

b. RMB > Insert > Sizing.

c. Change “Type” to “Number of Divisions”.

d. Set Number of Divisions = 25.

e. Set Behavior = “Hard”. 15. Remesh the model (highlight the mesh branch):

• RMB > Generate Mesh.

14a.

14b.

15.

14d.

14c.

14e.

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Edge Size Control Review the mesh metric as compared to the original mesh. With just a few refinements overall mesh quality has improved.

Original Mesh Metric

Final Mesh Metric

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…To go further

To go further, suppress previous meshing options and define :

a) an inflation on the center hole

b) a sphere of influence on the 4 faces shown on the picture

c) a pinch to repare CAD default on the edges shown below

a)

b)

c)

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Appendix

After creating mesh, in case of mesh setting changes, a color code is applied on the existing mesh in order to know the meshing state. As shown in this WorkShop, orange color indicates an obsolete mesh. It is necessary to re-run mesh.