biw interior acoustic

[zerodof]

Has anybody got any current industry experience of coupled acoustic modelling. I am interested in modal frequency response analysis. What sort of mesh density can give optimistic results on bothe structural and cavity.

thanks

 

[mert1]

I have been working on similar things for about a year now. One thing I want to point out; I understand that you want to fill and couple the air with the BIW structure. I use akusmod (msc software) to generate air. However, you should need a trim body model in which no openings are available and then the air is generated (depending on the mesh size) into the interior cavity of the vehicle
(structure).For a BIW model I never experimented manual air generation but still I see that you need some kind of constraint on the openings (ex. doors , etc.)

 

[zerodof]

What would you expect if you use manual mesh.What parametres should be chosen to get optimistic results on ACMODL

 

[mert1]

Manual mesh will have a better quality since the mesh size will be adaptive not fixed. It may be time consuming though. I will take a look at ACMODL.

 

[mert1]

Hi zerodof,
I was looking at the ACMODL, I did not use it before as our nastran decks are slightly different and as we are using AKUSMOD. I am not sure if you have the any kind of guide, but I am using quick reference quide and the format is as follows,
1 2 3 4 5 6
12345678123456781234567812345678123456781234567812345678
ACMODL INTER INFOR FSET SSET FSTOL

I would try INTER=DIFF (If only one side of the structure interacts with the fluid) , INFOR=ALL, FSET and SSET id numbers and some FSTOL value which is 0.001 if left blank.
In the deck you will have SET1=(id of fluid points) and SET2=(id of structure points).

Lets see if it works.

 

[mert1]

Remark: The numbers shifted !

 

[mert1]

zerodof,

for a better explanation, take a look at:

msc.nastan 2004 release guide

chapter 7 talks about how to use ACMODL

find it at mscsoftware.com

 

[zerodof]

Mert1
thanks for that. Did you use BW or CP option.