FFT and IFFT of PSD acceleration and stress
FFT and IFFT of PSD acceleration and stress
(OP)
Hello,
given a test request which specifies a random vibration profile as a PSD and after running a simulation to get a PSD stress, is it possible to simply carry out inverse fft of the responce (nm^2)^2/Hz to get the stress in the time domain (nm^2/s) and then carry out rainflow counting to estimate fatigue?
The simulation uses modal and linear dynamics to get PSD repsonse.
thanks in advance
given a test request which specifies a random vibration profile as a PSD and after running a simulation to get a PSD stress, is it possible to simply carry out inverse fft of the responce (nm^2)^2/Hz to get the stress in the time domain (nm^2/s) and then carry out rainflow counting to estimate fatigue?
The simulation uses modal and linear dynamics to get PSD repsonse.
thanks in advance





RE: FFT and IFFT of PSD acceleration and stress
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: FFT and IFFT of PSD acceleration and stress
Fe
RE: FFT and IFFT of PSD acceleration and stress
im not questioning your responces, just desporatly trying to clarify what is essentially a complex subject that i for one have been going in circles with.
RE: FFT and IFFT of PSD acceleration and stress
RE: FFT and IFFT of PSD acceleration and stress
when you form the psd, the phase information is lost
now you can make assumptions about the system response and construct a phase response per your reference, then reconstruct the time series from the data, but it is no longer the actual data but a guestimate...
RE: FFT and IFFT of PSD acceleration and stress
I suggest that you re-read page 3, which explains exactly what the author meant.
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize