Hi

Please be adviced that I have not used ABAQUS since the mid 90's.

As you did not get a reply, I looked aroud a bit.

Here is the definition of acoustic materials in Abqaus

http://www.ilsb.tuwien.ac.at/v6.11/books/key/default.htm?startat=ch01abk02.html#usb-kws-macousticmed

You find some example problems here

http://www.ilsb.tuwien.ac.at/v6.11/books/exa/default.htm?startat=ch09s01aex129.html

As a comment. Acoustic absorbers can be modelled from simple (e.g. complex wave speed) to more advanced (e.g. Biot Theory). You need Biot theory only when the structure path through the absorber matters, e.g. when analyzing a built up wall design where this transfer may affect transmission.

It may be useful to know also that acoustic Biot theory was a spin off from theory on soil analysis.

A word of general advice for modelling. Start simple, then complicate. Even if your task is to analyze objectX, it usually pays to start by simulating something simple to make sure that one operate the software as intended.

As food for thought, start by simulating a hard walled tube. You can FE/hand calculate resonance frequencies. We know that there should be very little effect from absorbers near the walls and high effect when placed at the center. Then, make one wall open ended and analyze instead this case. Once you know how to do this, move on to objectX. 

Ramblings on this subject can be found here if you are interested

http://qringtech.com/learnmore/why-simulate-measure-correlate-automate/

Sincerely

Claes

Hi Abbas

you can use the acoustic medium. Regarding bulk modulus, you are right.