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coupling vibration of a plate and acoustic

Posted Aug 29, 2024, 4:25 a.m. EDT 2 Replies

Filippo Tosato
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Hello, I m trying to couple the vibration of a plate due to an harmonic force, and the propagation in the air domain. basically i want to study spl in the air domain due to vibration. Could you have any suggestion how to do it in terms of step? I need both time domain and frequency domain. I have use acoustic-structure multiphysics. I have followed the tutorial gear noise but it doesn't work. I try to set as boundary condition in the pressure acoustic, frequency domain normal acceleration from solid mechanisms but i do not know how to implement it (using also general extrusion to couple the domains but it s not working). I also plot the eigenmode of plate plus air and they look completely wrong any ideas?. Thanks in advance.

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2 Replies Last Post Aug 30, 2024, 4:39 a.m. EDT
Acculution ApS Certified Consultant
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Posted: 6 months ago Aug 30, 2024, 4:22 a.m. EDT

Mech: You assume 1 m thickness and plane strain, which is the default, but check if your setup is actual this.

Acoustics: It is a tiny mech structure, so the sound field looks the same as this unless you go to very low frequencies, where it is less 'beamy'.

Coupling: No need for genext (and you are not using it, as far as I can see). The coupling is done under Multiphysics and all boundaries have been selected. You place a point load right at the interface, so that node is probably excluded from the coupling.

BC: Frequency Domain - You have input the the point load with more than the phasor, so instead of 20 e^(i omega t), you should just write 20. The 20 is a phasor of magnitude 20 and phase 0. If you need a phase also, let's say 1 rad, you write 20*exp(i 1[rad]), or you can split it into real and imaginary, so 4+3i or whatever, which has a magnitude of 5.

Wait with time-domain until you are happy with freq domain.

All in all, it looks okay. Change the load to 20, remove the genext, and you should be good.

-------------------
René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
Mech: You assume 1 m thickness and plane strain, which is the default, but check if your setup is actual this. Acoustics: It is a tiny mech structure, so the sound field looks the same as this unless you go to very low frequencies, where it is less 'beamy'. Coupling: No need for genext (and you are not using it, as far as I can see). The coupling is done under Multiphysics and all boundaries have been selected. You place a point load right at the interface, so that node is probably excluded from the coupling. BC: Frequency Domain - You have input the the point load with more than the phasor, so instead of 20 e^(i omega t), you should just write 20. The 20 is a phasor of magnitude 20 and phase 0. If you need a phase also, let's say 1 rad, you write 20\*exp(i 1[rad]), or you can split it into real and imaginary, so 4+3i or whatever, which has a magnitude of 5. Wait with time-domain until you are happy with freq domain. All in all, it looks okay. Change the load to 20, remove the genext, and you should be good.
Filippo Tosato
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Posted: 6 months ago Aug 30, 2024, 4:39 a.m. EDT

thanks so much, i solve it.

thanks so much, i solve it.

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