Learning Forum

[noahveenstra]

Hi all,

I am trying to do an acoustic analysis in Mechanical APDL that is based on a modal simulation that feeds the random vibration analysis of a Shell281 panel with a Fluid220 acoustic environment. I am trying to retrieve a sound pressure level (dB) Vs. frequency (Hz) response, where the panel is being excitated by an input PSD spectrum. I have managed to obtain good results for the response PSD of the panel, but cannot find a way to extend a similar analysis for the acoustic response of the Fluid220 environment. I have gone through all of the material in the acoustic analysis guide and tried all the relevant examples. In the acoustic guide, section 10.1.4 provides the conditions and limitations for performing an acoustic analysis using a spectrum input and gives the example of water sloshing in a cylindrical tank based on an SPRS excitation, suggesting to me what I am looking for can be done. However, in chapter 12 of the acoustic guide, only modal, harmonic, and transient models have postprocessing options. Further, when I run my simulation with and without my spectrum analysis code, I get the same results when I use commands like PRNSOL and PRVAR, confirming the acoustic data are being populated by my modal analysis. 

Essentially, I want to know if it is possible to get frequency-based acoustic results from the combination of a modal and random vibration analysis.

Thanks,

Noah

[Erik Kostson]

Hi

That is not possible (random vibration + acoustic).

The tank example (is not sloshing by the way - see limitations can not account for that) is something different.

Closing this post as it might be useful to others.

All the best

Erik