FRF from FE Model
FRF from FE Model
(OP)
I have a FE model for a deck, I obtained the displacement response at location B due to a unit sinusoidal load over a frequency range at any input location A. Can this response I obtained be called as a Frequency Response Function?





RE: FRF from FE Model
Cheers
Greg Locock
RE: FRF from FE Model
Eg Mobility = velocity/force [(mm/s)/N]or Compliance =displacement/force [mm/N] or Accelerance = acceleration/force [(mm/s^2)/N] i.e. output per unit of input. Having just output, say velocity as function of freq. cannot be called a transfer function, its just a single response to a single input. Having output per unit of input allows you to predict responses to any inputs.
RE: FRF from FE Model
Neither an FRF or a transfer function has to include force. And force could go on top or underneath.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: FRF from FE Model
An FRF can then be formed that relates the response acceleration to the base acceleration.
The FRF is a complex function of frequency, as mentioned in previous messages.
The response metric could also be relative displacement.
Tom Irvine
www.vibrationdata.com
RE: FRF from FE Model
If you obtained the displacement response at location B due to a unit sinusoidal load over a frequency range at any input location A, because its a unit force, the magnitude will be correct for FRF (divided by one), but you still need to include phase shift. Remember when you divide one complex number by another, the magnitudes divide out, but the phase angles are subtracted. Thus his output will contain the magnitude same as FRF but not the phase.
RE: FRF from FE Model