Check validity of mode shapes

Use the Post Processing Navigator

You can view the normal mode shapes in the Post Processing Navigator. For more information, see View the normal mode shapes.

Use Quick View

The Quick View command allows you to view the solved mode shapes in a contour plot.

1. In the Simulation Navigator, locate the node for your Response Dynamics solution process.

2. Under Modal Representation, right-click Normal Modes, Constraint Modes, or Attachment Modes and choose Quick View.

3. Use the buttons in the Results tab to display the contour plot of the next, previous, last, or first mode, or to play an animation.

Use the Response Dynamics Details View subpanel

You can use the Response Dynamics Details View subpanel in the Simulation Navigator to view information about the solved mode shapes and assess the accuracy of your modal model.

1. In the Simulation Navigator, locate the node for your Response Dynamics solution process (indicated with the icon).

2. Under Modal Representation, select Normal Modes. The detailed information for each mode appears in the Response Dynamics Details View subpanel.

3. For each normal mode, you can view the undamped frequency, damped frequency, the direction-specific effective mass values (%X_Mass, %Y_Mass, and %Z_Mass) and the total mass.

4. Use the Total Effective Mass value (which appears at the bottom of the subpanel) to assess whether there are enough modes in the excitation direction of interest to account for the responses you will be evaluating. If you were to solve for all modes and have them all set to Active in your analysis, you would have a total effective mass of 100 percent in the X, Y, and Z directions. For example, if you will be applying an excitation in the Z direction, but the effective mass in the Z direction is only 1 percent, you may need to solve for more modes. The generally accepted percentage is 80 percent for an accurate modal representation. Typically, you deactivate the modes that have the smallest mass values in the direction of interest.Note: If you have a large static component of load, Mode Acceleration data recovery may produce accurate results with a more limited set of modes.

Use the Modal Representation Information listing

To view a summary of the generated modal information:

• In the Simulation Navigator, right-click the Modal Representation node and choose Information.

The report includes this information:

• The types of results included in the solution (as defined in the Structural Output Request in the Dynamics subcase).

• The frequency of each normal mode generated.

• Information about the generated constraint modes, attachment modes, distributed attachment modes, equivalent attachment modes, and effective masses, as well as the types of results associated with each.

• Load vector associated with distributed attachment modes.

How do I

Create a Response Dynamics solution process

Clone a Response Dynamics solution process

Select or remove modes to analyze in Response Dynamics

Clear the obsolete status of a Response Dynamics solution process

Learn more

Simcenter 3D Response Dynamics

Response Dynamics workflow

Simulation Navigator for Response Dynamics

Post processing response results after clearing the obsolete status

CBUSH element force in Response Dynamics

Random Base Excitation

Response Dynamics Function Toolkit

Look up more details

Response Dynamics Details View subpanel (Simulation Navigator)

Response Dynamics status labels

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

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Related Topics

Deactivate modes by mass limit in Response Dynamics

Check validity of mode shapes, Simcenter 3D 2021.1 Series

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