S.E.A. Transmission loss factor

[BerndK]

Currently I’m creating a SEA-Model of a car to calculate the power flow of the elements like dashpanel and underbody and the interior noise. A SEA-Model has a validated frequency range from 400Hz to 5kHz. The connection of the elements with the interior cavity and to each other is described by a transmission loss factor. This factor describes the sound radiation, absorption, structural damping and the mass-law of each element and is the sum of all of these loss factors.
It is quite difficult to get any information about these factors of a panel with a carpet which is used in a car.
So may be someone knows some data which he can send me.

It is absolutely clear that the transmission loss factor varies between different cars, but this influencing quantity can be check with an sensitivity analysis.

Than you in advance for your support!

 

[MikeyP]

You seem to be talking about the Total Loss Factor, which is defined for each subsystem as the gross total energy taken away from a susbsystem during 1 radian cycle. That is the energy transfered to other subsystems through coupling plus the internal loss factor (the ILF includes the damping of the subsystem and energy losses to other parts of the physical system not included in the SEA model) of the subsystem itself.

To obtain a model that even remotely agrees with measurement, the answer is almost always to measure the TLF rather than try to predict it. You can do this for an in situ panel by measuring the structural reverberation time (T60) and using the formula:

TLF = 2.2*f/T60 where f is the band centre frequency.

M

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