Multiresolution Wavelet Analysis of the Dynamics ofa Cracked Rotor

[摘要] We examine the dynamics of a healthy rotor and a rotor with atransverse crack, which opens and closes due to its self weight. Using discrete wavelet transform, we perform a multiresolutionanalysis of the measured vibration signal from each of theserotors. In particular, the measured vibration signal is decomposedinto eight frequency bands, and the rms amplitude values of thehealthy and cracked rotors are compared in the threelowest-frequency bands. The results indicate that the rmsvibration amplitudes for the cracked rotor are larger than thoseof the healthy rotor in each of these three frequency bands. Inthe case of externally applied harmonic force excitation to therotor, the rms values of the vibration amplitude of the crackedrotor are also found to be larger than those of a healthy rotor inthe three lowest-frequency bands. Furthermore, the difference inthe rms values between the healthy and cracked rotors in each ofthe three lowest-frequency bands is more pronounced in thepresence of external excitation than that with no excitation. Theobtained results suggest that the present multiresolution approachcan be used effectively to detect the presence of a crack in arotor.

[学科分类] 力学，机械学