I am working on modal testing of structures using forced hammer excitation.
Response time series has a sampling frequency of 250Hz and the excitation time
series has a sampling frequency of 500Hz. Should the plot of FRF magnitude
versus frequency be as a function of the response or excitation frequency? Or
which sampling frequency would govern the FRF plot?
Secondly, for a single-point excitation responses are measured at 5 different
points. Is it possible to calculate the FRF as the ratio of FFT(X)/FFT(P), where
X is a (n x 5) matrix representing the response time histories from the 5
measuring points and P is a vector representing the excitation time history.
Thank you for the anticipated prompt response.
