Hilbert-Huang Transform and Its Application to Crack Identification for Start-Up Rotor

A crack not detected in time can result in the catastrophic failure and cause injuries and severe damage to machinery. In this paper, a crack identification method for start-up rotor based on Hilbert-Huang Transform (HHT) is addressed. With this method, each Intrinsic Mode Function (IMF) of the vibration signal is obtained by Empirical Mode Decomposition (EMD). Then the spectrum of instantaneous frequency is accordingly calculated via Hilbert transform and is employed to detect the weak crack during the start-up process of the rotor system. To verify the validity of the mentioned method, an experiment with a cracked shaft was conducted on the Bently rotor test rig in the steady accelerating process. The results in the simulation and experiments show that HHT appears to be a more effective tool for the analysis of non-stationary vibration response of the weak cracked rotor compared with Fast Fourier Transform (FFT) and Continue Wavelet Transform (CWT).