Questions about sound damping

Dennis_20682

Hello everyone,

i'm trying to simulate interior acoustics with Optistruct using coupled frequency response analysis. In my model i have multiple surfaces with different materials assigned. I know the sound absorption coefficient for those surfaces but i don't know how or if it's possible to model this in optistruct. So my questions are:

• Is it possible to assign a sound absorption coefficient to different Materials/Properties/Elements?
• If i can't assign a sound absorption coefficient directly, is there any other way to achieve sound damping in optistruct?
• If it's possible, is it also possible to do that frequency dependent?

Thank you all in advance

Xiaolei

Hi Dennis,

Although directly defined absorption coefficient(transmission loss)based is more straightforward, it's not available in 2024.0 version, and we are still in the process of enhancing this feature. For now we need to wait until it is implemented.

If poro-elastic material properties are available, you can use the below method.

https://help.altair.com/hwsolvers/os/topics/solvers/os/poroelastic_materials_r.htm?zoom_highlight=biot

https://help.altair.com/hwsolvers/os/topics/solvers/os/matpe1_bulk_r.htm?zoom_highlight=biot

If impedance is available, you can use PAABSF.

https://help.altair.com/hwsolvers/os/topics/solvers/os/paabsf_bulk_r.htm?zoom_highlight=paabsf

Thanks.

Xiaolei

Dennis_20682

Xiaolei Song_21874 said:

Hi Dennis,

Although directly defined absorption coefficient(transmission loss)based is more straightforward, it's not available in 2024.0 version, and we are still in the process of enhancing this feature. For now we need to wait until it is implemented.

If poro-elastic material properties are available, you can use the below method.

https://help.altair.com/hwsolvers/os/topics/solvers/os/poroelastic_materials_r.htm?zoom_highlight=biot

https://help.altair.com/hwsolvers/os/topics/solvers/os/matpe1_bulk_r.htm?zoom_highlight=biot

If impedance is available, you can use PAABSF.

https://help.altair.com/hwsolvers/os/topics/solvers/os/paabsf_bulk_r.htm?zoom_highlight=paabsf

Thanks.

Xiaolei

Hi Xiaolei,

thank you for your quick answer. So, at least in theory and according to literature, it is possible to calculate what impedance at a boundary results in for example 50% absorption and 50% reflection. Would Optistruct be able to model this? This seems to be the only possibility to setup the model how i need it to at the moment.

I'm looking forward to further enhancements in Acoustic Simulation in Optistruct.

Thank you,

Dennis