I'm trying to perform FFT analysis on data from an engine "rpm sweep" test to find resonance peaks on the DUT. There are three tri-axis accelerometers along with time, engine speed, engine torque, channels. One accelerometer is placed on the engine "base" and two on the DUT. Data is sampled at 5 kHz and sync'd across all channels.
I'm wondering how to go about setting up the FFT windowing to do this? I'm not very familiar with vibration. I have tried setting up the FFT with a one window across all the data, but the result was a lot of low magnitude data with no discernible resonance peaks. Is this approach correct, or am I setting up the FFT window incorrectly? I'm using DIAdem for the signal processing.