MSC Nastran vibro-acoustic analysis

Using MSC Nastran, you can create and solve a vibro-acoustic solution which lets you study the interaction between the vibrations of a structure and the surrounding acoustic fluid.

Supported solutions for vibro-acoustic analyses

For a vibro-acoustic analysis, you can create the following types of solutions:

• SOL 103 Real Eigenvalues

• SOL 111 Modal Frequency Response

• SOL 111 Modal Frequency Response Functions

• SOL 200 Design Sensitivity Analysis

For these solutions, the software computes the normal modes separately for the structural and fluid portions of the model. The uncoupled modes of the structure and fluid are used in the modal formulation of the stiffness, mass, and damping.

Creating the structural and fluid meshes

In a FEM file in the MSC Nastran environment, you can create the necessary structural and fluid meshes for a coupled vibro-acoustic analysis. You can also define a fluid mesh only for an acoustic analysis. You can use linear and parabolic CTETRA, CHEXA, and CPENTA acoustic fluid elements to create 3D fluid meshes.

For more information, see Meshing for FEM acoustic analysis.

Defining the interaction between the structure and the fluid

If your model includes both structural and fluid meshes, you can have the software automatically couple those meshes together at their common interface. For more information, see Modeling fluid-structure coupling and interaction (MSC Nastran).

Defining modal damping

In a vibro-acoustic SOL 111 Modal Frequency Response or SOL 200 Design Sensitivity Analysis solution, you can define modal damping separately for structural and acoustic fluid entities.

• You can use the Mode Selection for Structure and the Mode Selection for Fluid options on the Case Control tab of the Solution dialog box or in the Solution Step dialog box to select the structural and fluid modes.

• You can define uniform structural damping and uniform fluid damping in the parameter groups on the Bulk Data tab of the Solution dialog box. These options correspond to the G, GFL, KDAMP, and KDAMPFL parameters.

Output requests for vibro-acoustic analysis

You can use the Vibro-Acoustic Output Requests modeling object to request the types of output the software lists to the .f06, .op2, or punch file .pch when you solve your solution. In the Vibro-Acoustic Output Requests dialog box:

• Use the Grid Contribution options to request output of structural node (grid) contributions to the acoustic response. The Grid Contribution options correspond to the describers for the PFGRID case control command.

• Use the Modal Contribution for Fluid and Modal Contribution for Structure options to request modal participation factor output for structural and fluid modes. The Modal Contribution for Fluid and Modal Contribution for Structure options correspond to the describers for the PFMODE case control command.

• Use the Panel Contribution for Fluid and Panel Contribution for Structure options to request acoustic panel participation factor output for structural and fluid modes. The Panel Contribution for Fluid and Panel Contribution for Structure options correspond to the describers for the PFPANEL case control command.

Note:

You can use the Acoustic Output customer defaults to control whether any of these output requests are selected by default when you open the Vibro-Acoustic Output Requests dialog box.

Where do I find it?

Vibro-acoustic analysis

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed partMSC Nastran as the specified solverVibro-Acoustic as the specified analysis type
Command Finder	Solution

Fluid-Structure Interface Parameters, Fluid-Structure Interaction Control Parameters, and Vibro-Acoustic Output Requests modeling objects

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed partMSC Nastran as the specified solverVibro-Acoustic as the specified analysis type
Command Finder	Modeling Objects

Customer defaults for Vibro-Acoustic Output Requests options

Command Finder	Customer Defaults
Location in dialog box	Simulation→Pre/Post→Nastran→Output Requests page→Acoustic Output Requests

Learn more

Modeling fluid-structure coupling and interaction (MSC Nastran)

Quick links

Command reference

Pre/Post video examples

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MSC Nastran vibro-acoustic analysis, Simcenter 3D 2021.1 Series

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