A modulation instantaneous autocorrelation bispectrum method for accurate fault diagnosis of planetary gearboxes

Planetary gearboxes with high-power density are employed extensively in industrial applications. To increase the efficiency and safety of planetary gear sets, fault detection and diagnosis is highly desired to service the decision support and maintenance planning. Vibration based fault diagnosis of planetary gearboxes attracts many researchers working on the modulation phenomenon and time varying transfer paths. However, the stationary working conditions are ideal, but the modulation signals are not stationary in practice as the instantaneous rotating speed slightly varies due to power sources or external loads. The stationary demodulation analysis is not capable to tackle the nonstationary modulation vibrations. Therefore, the modulation instantaneous autocorrelation bispectrum (MIAB) method is developed to extract the high-order cyclic features hidden in the cyclostationary vibration responses. The experimental studies of on-rotor sensing vibrations collected from a test rig with healthy and faulty planetary gearboxes were conducted to verify the effectiveness of the proposed MIAB method. The diagnostic results show the MIAB method is effective and reliable to extract compound fault signatures of planet gears and sun gears.