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From FEM to Acoustics Model with Sysnoise

From FEM to Acoustics Model with Sysnoise

(OP)
Is there any body to help me?How can i authomaticaly produce acoustics model and mesh them.....in LMS_SYSNOISE.
My FEM model is a complex engine model ,and i want to calculate SPL with in Frequency Interval 500- 4000 Hz.

thanks for your help
Gudro

RE: From FEM to Acoustics Model with Sysnoise


Have you tried LMS Virtual.Lab ? They have a Sysnoise equivalent now embedded within Virtual.Lab and it has mesh coarsening and many advanced acoustic meshing tools.

RE: From FEM to Acoustics Model with Sysnoise

Hai,

  Acoustic model is numerically represented by FE(finite elements) or BE(boundary elements) in sysnoise.

   The choice of FE or BE depends upon what you want to do?

 For exterior radiation BEM is better than FEM, mainly on economy front.

  If you have Finite element model of engine block.Then you can build boundary element mesh automatcially in sysnoise by skinning the solid mesh.
  Apply the appropriate boundary conditions and solve for the exterior radiation.

  I want to add one further comment in this regard. The upper range 4000Hz seems to be high.It will take more time to solve the domain.

  Statistical energy analysis may be a better technique at high frequencies.
 As mentioned by manam, the new vitual lab  has mesh coarsening and many advanced acoustic meshing tools.It will to prepare the acoustic model faster.

Regards,
Logesh.E
 

RE: From FEM to Acoustics Model with Sysnoise

(OP)
Thanks a lot manam and elogesh for your Help!

-The First Problem , still i havn't LMS Virtual.lab, i will try to find this additional Program for SYSNOISE.

-Elogesh.. you seggest me from solid FEM Model to  build boundary element mesh automatcially in sysnoise by skinning the solid mesh.
 you min without using LMS Virtual.lab...can we skinning the solid mesh... if so ..how you do it? please explain me
is there any comand there to skinning the solid mesh?

Regards
Gudro

RE: From FEM to Acoustics Model with Sysnoise

Hi Logesh,

I have a few questions for you.

1. In SYSNOISE, can i build the whole geometry and mesh it (instead of importing?)

2. At the moment, Iam trying to use ANSYS for low frequency acoustic analysis (Harmonic analysis) but iam not able to apply a velocity to excite the fluid to get SPL. is ansys not capable of performing acoustic analysis (and get SPL at desired nodes) of simple structures?

Srini

RE: From FEM to Acoustics Model with Sysnoise

Hai,

 Gudro: what is the module you have!! i.e.,IFEM,DBEM,IBEM,FEM,etc.

 You have to choose the right model option-> BEM(boundary element method) before skinning the solid mesh.

   Srinivasanpuri:
You can't build geometry in sysnoise. Sysnoise is a solver+post-processor.

  ANSYS is capable of doing acoustic analysis. But the economy is not quite good. It takes considerably longer time to solve and has a quite a big database.

   The acoustic analysis, I carried out quite a long time back was tranmission loss analysis of muffler.
We used to specify the inlet acoustic pressure and at the outlet quantity equivalent to acoustic impedance.
  --------------------------------------------------
    If possible, I will collect fewmore details and get back to you soon.

Regards,
Logesh.E

  

RE: From FEM to Acoustics Model with Sysnoise

Hi logesh,

Thanks for your reply..Actualy, what i have so far done using ansys is:

1. calculated the acoustic natural frequencies of a cavity

2. tried to conduct a harmonic analysis of structure(rectangular cavity) with fluid (air) inside.

I have not been succesful in getting results from the harmonic analysis. basicaly what iam trying to do with the harminic analysis is calculate SPL using a forcing frequency range by exciting the structure-fluid...

is what iam carryin out right for the aim i mentioned?

srini

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