Calculate natural frequency and damping for given set of enhanced FRF and shapes
[fesyn,st] = efrf_fit(fe,sm,nlines,type)
EFRF_FIT calculates the natural frequency and damping for a set of mode shapes given a set of enhanced FRF and starting estimates of the natural frequencies.
FE is an imat_fn containing the enhanced FRF, one per shape to fit.
SM is an imat_shp that must contain the same number of shapes as there are functions in FE. The .Frequency property of these shapes contains the initial guess for the resonant frequency which EFRF_FIT will extract from FE.
NLINES is a numeric scalar specifying the number of frequency lines on each side of the closest spectral line in FE to the corresponding frequency estimate in SM.Frequency to use for the best fit estimate.
TYPE is an optional string specifying which portion of the FRF to use in the frequency and damping estimate curve fits. Valid options are
'imag' | Use only the imaginary portion of the FRF |
'both' | Use both real and imaginary portion of the FRF [Default] |
Two outputs are supported.
FESYN is an imat_fn containing the synthesized enhanced FRF based on the best fit modal parameters.
ST is SM, with the frequency and damping properties replaced with the best fit values.
>> [fesyn,st] = efrf_fit(fe,sm,5,’imag’)
>> for jj=1:length(fe); plot([fesyn(jj);fe(jj)]); end