Mapping measured or computed modes to a mesh

You can use the Modal Expansion noise and vibration solution to map measured or computed mode shapes from an input mesh (for example a wireframe from Simcenter Testlab) onto a reference finite element mesh in your simulation. You can then visualize the expanded modes in post-processing and use the expanded modes in a hybrid structural or vibro-acoustic analysis of measured and computed results.

A structural mesh can be very detailed, so Modal Expansion allows greater use of measurement data (which is typically available only on a very reduced set of measurement points) in your simulations with a more complete description of structural behavior.

Performing a Simcenter 3D Noise and Vibration Modal Expansion solution to expand mode shapes is a three-step process. The objective is to expand the mode shapes from a coarse mesh to a detailed mesh.

1. Compute or measure mode shapes on a coarse (data source) mesh.

2. Solve a SOL 103 Real Eigenvalue solution on the target mesh to compute the reference mode set on which the input mode shapes will be expanded.

3. Perform Modal Expansion to expand the data source mode shapes to the target mesh.

You can import the mode shapes from:

• Nastran results file (.op2)

• Simcenter 3D HDF5 data file (.sc_h5)

Note:

Typically, you expand a mode shape from displacements if you will perform further analysis. Simcenter Nastran only supports mode shapes as displacements.

For more information see Expanding mode shapes to a mesh workflow.

How do I

Displaying alternate FEM representations

Replace a FEM file with a mode set or FRF set

Editing modes or functions in mode sets and FRF sets

Edit a mode set or FRF set

Learn more

Mode sets

Controlling mesh creation for mode sets

Generating modal model results for a mode set

Replace a component FEM file in an assembly FEM with a mode set

Plot mode, ATV, or VATV set contours

Mode set theory and damping

Viscous and structural damping values in mode sets (Simcenter Nastran)

Using Modal Expansion to expand measurements to a FEM

Expanding mode shapes to a mesh workflow

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Related Topics

Assembly FEM

Mapping measured or computed modes to a mesh, Simcenter 3D 2021.1 Series

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