Adaptive demodulated resonance diagnosis for the gear faults

A scheme of using adaptive demodulated resonance technique (ADRT) for early detection of gear tooth faults diagnosis is introduced. The objective is to supplement the current technique of gearbox fault diagnosis based on the synchronous averaging technique and demodulation analysis. The proposed scheme focuses on the fact that gear tooth faults will produce vibration impacts that would excite the structural resonances when the failure tooth is engaged. The high-frequency structural resonance can be auto-identified from the vibration spectrum computed using an FFT algorithm. Using this scheme, the regular gear meshing harmonics are first removed from the synchronous signal average to generate the residual signal. The residual signal is then band-pass filtered around the high-frequency structural resonance which is auto-identified from the vibration spectrum. The band-pass residual signal is demodulated to extract the features related to the fault-induced sudden change in a complete revolution of the gear of interest. The method is validated using test data from a gearbox rig. The results show that ADRT is an effective tool for the detection of the incipient faults and locating the faults in the gear.