Modal-based forced response with vibro-acoustic coupling (Acoustics BEM)

In vibro-acoustic models you can use a mode set that was computed in a Nastran structural analysis to represent the structure.

A modal model (Mode Set) is a reduced form of the structural dynamic characteristics with a smaller number of degrees of freedom. For more information about mode sets, see Mode sets.

An uncoupled structural model mesh is not supported for representing a mode set. You must couple the structural mesh and fluid mesh. You can define the coupling of the mode set to the acoustic fluid in the following ways:

• Two-way coupling (strong) — Transfers the effect of structural vibration to the fluid, and then transfers the resulting acoustic pressure loads to the structure.

• One-way coupling (weak) — Transfers the effect of structural vibration to the fluid only, and ignores the effect of the fluid pressure on the structure.

Structural loads

You can apply structural loads as forces and moments on the mode set that represents the structure.

You can also define oscillating forces and moment loads with:

• Complex numbers with real and imaginary parts

• Magnitude and phase

Acoustic loads

All acoustic loads are supported for both two-way coupling (strong) and one-way coupling (weak).

Where do I find it?

Adding the mode set to the model

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partAn assembly FEM file (.afm)Simcenter 3D Acoustics BEM as the specified solverIndirect Vibro-Acoustic as the specified analysis typeVibro-Acoustic Response as the specified solution typeA Mode set computed in Simcenter Nastran or MSC Nastran
Simulation Navigator	Right-click the assembly FEM file→Edit Representation
Location in dialog box	FE Model Component Representation dialog box→Representation list→Mode Set

Creating a fluid-structure interface and defining a coupling type

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter 3D Acoustics BEM as the specified solverIndirect Vibro-Acoustic as the specified analysis typeVibro-Acoustic Response as the specified solution typeA Mode set computed in Simcenter Nastran or MSC Nastran
Simulation Navigator	Right-click an active indirect vibro-acoustic solution→Edit
Location in dialog box	Solution dialog box→Vibro-Acoustic Coupling group→Fluid-Structure Interface Modeling Parameters→Create Modeling Objects

Learn more

Acoustics BEM solver environment

Acoustics BEM workflow

Acoustics BEM remote solving workflow (Linux)

Checking your model prior to solving (Acoustics BEM)

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Modal-based forced response with vibro-acoustic coupling (Acoustics BEM), Simcenter 3D 2021.1 Series

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