Acoustic cavity mode shape, Vehicle modeshape , Acoustic radiation. 1

[Madjid Bentorki]

Hi there,

I've recently started an internship to analyze using nastran (ansa,meta), the acoustic radiation caused by a vehicle trunk. The problem is that the vehicle trunk mode shape responsible for the sound heard is not at a frequency that is close to the acoustic cavity mode shape frequency that seems responsible for this acoustic radiation (longitudinal modeshape). And below that acoustic modeshape frequency there is only rigid body modes.

So my question is the Following : Is it necessary to have the same frequency from both the acoustic cavity and the vehicle trunk to affirm that the acoustic radiation caused by the vehicle trunk is transmitted through that acoustic cavity modeshape ? Is there some octave band to consider ? Does the damping has a role in this ?

Thanks a lot.

Kind regards.

M.Bentorki

 

[Erik Panos Kostson]

There will probably be more sound in the cabin especially if a structural mode excited coincides with an acoustic mode. Damping must of course play a role in the vibration amplitudes.

This video might be of help. Unfortunately I do not have any experience in vibroacoustic modelling using Nastran or Actran.

https://m.youtube.com/watch?v=r03_vd-tJaY

 

[Madjid Bentorki]

Hi Erik,

Thank you for the response I will check this video and see what this is about. Sorry for the late response though... .

Regards,

M.Bentorki