Simcenter Testing Solutions Animate CAD Geometry: Simcenter Testlab Modal Analysis

Simcenter Testlab



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When performing a modal analysis, it is common to create a simple wireframe geometry that represents the product under test (see Figure 1, left). This wireframe simply consists of the test nodes with lines linking the nodes together.

The wireframe geometry is adequate to display mode shapes, but often it is desired to animate CAD geometry with the test data to make the mode shape easier to understand.

With Simcenter Testlab Mode Shape Expansion it is possible to link together a wireframe and CAD geometry so that the modes can be animated on the full CAD geometry. Simcenter Testlab was previously called LMS Test.Lab.

Look at Figure 1 below to see how animating the CAD geometry gives a more complete picture of the mode shape than just the wireframe.

Figure 1: Before: Just the wireframe animates. After: Animation expanded to CAD model.

To animate the CAD, links between the wireframe and the CAD must be established. These links will allow the CAD to move with the wireframe as the mode shape is animated.

To link the wireframe and the CAD, follow the steps below:
1. Import the CAD file of the Object under Test
2. Import the Wireframe Geometry
3. Link the CAD and Wireframe Together
4. Display Mode Shapes

1. Import the CAD file of the Object under Test

In this example, a fixture was tested. The .stl file is imported into the Geometry workbook.

Figure 2: Import a CAD file to the Geometry workbook.

2. Import the Wireframe Geometry

Now, the wire frame created in Simcenter Testlab Geometry must be superimposed onto the CAD geometry.

To add the wireframe, highlight the component(s) in the browser tree on the left of the screen and click “Duplicate/Import Component”.

Figure 3: The wireframe consists of five components. Select all five components in the tree on the left of the screen and then select “Duplicate/Import Component”.

The wireframe and the CAD file are now both in the Geometry workbook. See Figure 4 below: the wireframe is superimposed over the CAD.

Figure 4: The wireframe is superimposed over the CAD.

NOTE: Take care to ensure the CAD file and the wireframe were created with the same coordinate system. Otherwise one of the two will need to be translated / rotated.

3. Link the CAD and Wireframe Together

An association needs to be made between the wireframe nodes and the CAD nodes. This will give the software the appropriate information about which wireframe node corresponds to which CAD node. This is required to animate the CAD geometry properly.

The association between the two geometries is done by drawing lines between the wireframe nodes and the CAD nodes.

Go to the “Lines” sub-worksheet of the Geometry tab. Add lines between nodes on the wire frame and nodes on the geometry that are at the same location.

Figure 5: Add lines between nodes on the wireframe and nodes on the CAD that correspond to the same location on the part.

NOTE: Not every node needs to be mapped, just enough to give definition to the model.

4. Display Mode Shapes

Now that the wireframe and the CAD are linked together, go to the Navigator to display some mode shapes.

In the navigator, add the entire geometry to a geometry display. This will bring in the wireframe and the CAD.

Drag and drop a mode shape onto the geometry. Initially, only the wireframe will animate. To animate the CAD as well, right click in the display, go to “Animation Settings” and turn on “Automatic Topological”.

Figure 6: Turn on Automatic Topological.

This will slave together any nodes between the wireframe and the CAD that are connected by lines. The geometries will become linked and both will animate at the same time.


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To remove the wireframe from the animation and just have the CAD animate, right click in the display and select Component Visualization.

Figure 7: Component Visualization will allow turning on and off the display of various geometry components.

The Component Visualization window will open. Turn off the visibility for all components except for the CAD.

Figure 8: Only leave on the visualization of the CAD.

Now, only the CAD will remain for the visualization.

Figure 9: The CAD animates while the wireframe is invisible.

The CAD and wireframe animations are now linked. This is a great way to obtain good-looking mode shape representations for presentations and reports.

For more information on visualization options, check out the Knowledge article "Simcenter Testlab: Geometry Display".

Questions? Email, post a reply, or contact Siemens Support Center.

Related articles:

Modal Data Acquisition

Modal Analysis and Operational Deflection Shapes

KB Article ID# KB000038016_EN_US



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