Creating acoustic constraints

You can apply constraints to a 3D acoustic FEM model in several ways. The acoustic fluid has only one degree of freedom (DOF1) which is fluid pressure.

In an Acoustic or Vibro-Acoustic analysis, nodes on the model boundary have a zero velocity, or no flow condition. This means that the acoustic boundary is rigid by default.

To apply fluid acoustic or vibro-acoustic constraints:

• In an Acoustic analysis with a zero pressure boundary, such as an air-to-water interface, you can apply a fluid constraint by editing the Nastran input file (.dat). You apply Single Point Constraints (SPCs or SPC1s), constraining DOF1 at the desired boundary nodes.

• In a Vibro-Acoustic analysis, where you have both 3D acoustic fluid and structural elements, you can apply any structural constraint to any structural node. You can constrain the acoustic fluid nodes, which are separate from structural nodes, by editing the Nastran input file (.dat). You apply Single Point Constraints (SPCs or SPC1s), constraining acoustic fluid DOF1 at the desired boundary nodes.

• In an acoustic or vibro-acoustic forced response analysis (SOL108 or SOL111), you can apply an acoustic pressure using an Enforced Acoustic Pressure to the boundary which represents the zero pressure boundary, such as an air-to-water surface. The enforced acoustic pressure can be zero, thereby applying a zero value pressure constraint to the chosen 2D fluid nodes.

How do I

Create an acoustic source load

Create an acoustic absorber

Learn more

Boundary conditions overview (FEM acoustics)

Defining acoustic load sets, sources, and pressures (FEM acoustics)

Random loading for acoustic and vibro-acoustic analysis (FEM acoustics)

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Creating acoustic constraints, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });