97 - understanding mirror symmetry constraints.pdf

7/27/2019 97 - Understanding Mirror Symmetry Constraints.pdf

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Structural Constraints Understanding Mirror Symmetry Constraints – Lecture

UnderstandingMirrorSymmetryConstraints.mp3 Understanding Mirror Symmetry Constraints

Symmetry constraints can be used to significantly reduce model

size.

Before Mirror Symmetry

After Mirror Symmetry Lecture Notes Symmetry Constraints

When the loads, constraints, and geometry of a model are symmetrical, you can takeadvantage of symmetry to analyze a portion of the model instead of the entire model.Symmetric constraints work by preventing the model from deforming through theplane(s) of symmetry. There are two types of symmetry constraints that can becreated in Mechanica: Mirror and Cyclic. We will focus on Mirror symmetry in this

topic.



Mirror symmetry is applied when the model, loads and constraints are symmetricalabout a plane. The model is cut in half through the plane, and then the constraint isapplied through the surface (solid model), edge (shell model), or point (beam model)

that lies on the plane of symmetry.

Best Practices

It should be noted that symmetry can only be used when the model, loads, andconstraints are symmetrical. If only the model is symmetrical, then the resultsgenerated will not be correct, or may be correct for stress but not displacement,or vice versa. The symmetry requirement for loads and constraints is oftenoverlooked.

Finally, users should note that when taking advantage of symmetry in models, amodal analysis or buckling analysis will only report the modes that aresymmetrical. As such, not all modes may be captured. For such analyses it isrecommended to not use symmetry.

Understanding Mirror Symmetry Constraints – Demonstration UnderstandingMirrorSymmetryConstraints_demo.mp4 Understanding Mirror Symmetry Constraints – Procedure

Procedure: Understanding Mirror Symmetry Constraints

Scenario

Create a mirror symmetry constraint.

CreateMirrorSymCons hb_support.prt

Task 1. Resume a cut feature and start the Mechanica application.

1. From the main menu, click Edit > Resume > Resume All.

This operation resumed a cut feature that removes all of the geometry in the

model except for the piece to which you are going to apply the mirror

symmetry constraint.

2. Click Applications > Mechanica.

Task 2. Create a mirror symmetry constraint.

1. Click Symmetry Constraint from the Mechanica toolbar.



2. Verify that the Type drop-down menu is set to Mirror.

3. Select the surface on the right side of the model as the reference for the mirrorsymmetry constraint as shown.

4. The dialog box should now appear as shown. Click OK to complete the symmetryconstraint.

5. The models should now appear with the Mirror Symmetry icon as shown.

Task 3. Save the model and erase it from memory.

1. Return to the Standard Pro/ENGINEER mode by clicking Applications > Standard.



2. Click Save from the main toolbar and click OK to save the model.

3. From the main menu, click File > Close Window.

4. Click File > Erase > Not Displayed > OK to erase the model from memory.

This completes the procedure.

97 - understanding mirror symmetry constraints.pdf

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