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#1 2020-11-13 10:19:01

danillocafaldo
Member
Registered: 2020-11-10
Posts: 3

Poroelastic material

Hello everyone,

I am new in the code_aster community and I am interested in performing vibroacoustics simulations, particularly aiming the acoustic response inside a closed cabin due to external excitation on the cabin walls. It is also of my particular interest to consider the acoustic absorption of poroelastic material inside the cabin, such as foams or fibers.

I could not find in the code_aster documentation such porous elements. I found one specific publication [1] in the literature, from 2017, affirming that code_aster at that moment did not have such feature implemented.

Anyone here with experience in such calculation would be able to tell me more about the availability and/or development of poroelastic materials on code_aster?

I appreciate your attention and support.

Danillo Cafaldo dos Reis

[1] GAROT M., et al, “Acoustic computation of a grommet in a small cabin using finite element analysis”, 23 ème Congrès Français de Mécanique, 2017

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#2 2020-11-18 16:35:10

CLF
Member
From: Sweden
Registered: 2009-01-27
Posts: 119
Website

Re: Poroelastic material

Hi Danillo

I cannot really answer your question as such.

There are soil material models that ought to work also for acoustics, though I have neither looked at, nor really tried them.

That said, CA executes in Python. So, you can mix and match.

This open source module runs in matlab.
github.com/JPPM-KTH/ARAMiS

If the built in material modes do not work, you can (probably, haven't tried this one either) either use these to generate matrix elements or drive Matlab from Python.

Aramis seems to compute absorption data. As it uses a transmission matrix method, I am guessing there might be meatier data that can be extracted from the code.

Hope this helps at least a little.

Sincerely
Claes

Last edited by CLF (2020-11-18 16:40:25)

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#3 2020-11-25 11:03:17

danillocafaldo
Member
Registered: 2020-11-10
Posts: 3

Re: Poroelastic material

Hello Claes,

thank you for your reply!
Indeed quite interesting your suggestions and the code you shared. I will look careful into that.
An impedance boundary condition does solve some of my problems, but in fact there are some cases that I would like to model the absorbing material as explicit 3D absorbing elements, using this poroelastic formulation.

Also, meanwhile, I was doing more research in the CA forum and I've found another interesting post, addressing the same problems that I am looking at (although I don't even have my case ready to share yet):

"Use of IMPE_FACE to add impedance to a vehicle VIBROACOUSTIC model"
(Apparently I cannot post links)

It seems to have reached the same questions in terms of absorbing elements modeling (IMPE_FACE/3D_FLUI_ABSO).

I will touch base in this referred topic, but I would like to leave this post open for further discussions of improvements in the explicit modelling those poroelastic materials. I would appreciate if anyone could share any recent developments on that or even the willingness to collaborate on the advancement of such approach.

Kind regards,
Danillo

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#4 2020-11-25 14:23:11

CLF
Member
From: Sweden
Registered: 2009-01-27
Posts: 119
Website

Re: Poroelastic material

Hi Danillo

As you know, the impedance boundary condition is correct only for one angle of incidence. It works fine for 1D.

For simple absorbing boundary conditions, you have a rubber band mesh that absorb.

A more rigorous bc is to use the BE code Miss3D. This one, I have not used.

Sincerely
Claes

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