Prestressed Acoustic-Structure Interaction

When modeling transducers like microphones or ultrasound horns there are often parts of the structure, like the diaphragm or a bolt, that are under tension or prestressed. In these cases it is essential to include this effect when modeling the traducer. A prestressed part will shift the resonance frequency of the mechanical system and thus the overall vibroacoustic behavior will change.

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Piezoelectric Tonpilz Transducer with a Prestressed Bolt: Application Library path .

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The Brüel & Kjær 4134 Condenser Microphone: Application Library path .

Such prestressed acoustic-structure iteration models can be set up and solved fully coupled including all effects. The procedure is as follows:

Set up the model including all relevant physics.

Couple the physics using the Multiphysics couplings.

All acoustic sources, structural loads, and any forcing that are non-static, for example, any acoustic source should be defined using the linper() operator. This will ensure that they are used only in the frequency domain part of the study (that one is set to linear perturbation).

Add a study.

Note that in the step the acoustics physics interfaces have an orange warning triangle under the . This simply means they will not be used in the stationary study since acoustics is not supporting the study type. Therefore the will automatically not be marked under the in the .

Note also that the box is checked in the step. If it is not checked the prestress effect is lost.

Solve the model for the desired frequencies.

A prestressed type of analysis can also be done on pure structural problems in the frequency domain and when searching for eigenfrequencies of structures.


	See also Prestressed Structures, Pretensioned Bolts, and Mechanical Damping and Losses in the Structural Mechanics Module User’s Guide