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Model ID: 188

Vibrations of a Disk Backed by an Air-Filled Cylinder

The modes of vibration of a thin or thick circular disk are well known, and the corresponding eigenfrequencies can be calculated to arbitrary precision from a series solution. The same is true for the acoustic modes of an air-filled cylinder with perfectly rigid walls. A more interesting question is: What happens if the cylinder is sealed in one end not by a rigid wall, but by a thin disk?

Here the coupled system will be modeled using the extended multiphysics approach. This means that the disk is drawn in a 2D geometry and modeled using Mindlin theory DRM plate elements, while the cylinder is drawn in a separate 3D geometry.

The acoustics in the cylinder is described in terms of acoustic (differential) pressure.

On the surface the normal acceleration and the displacement of the disk is shown. The isosurfaces shows the pressure in the cylinder for the eigenfrequency 2730.55 Hz.

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