Cyclostationarity analysis for gearbox condition monitoring: Approaches and effectiveness

Cyclostationarity matches the rhythmic feature of gearbox vibration and thus provides an effective alternative for gearbox condition monitoring. This paper concerns with the applications and the effectiveness of cyclostationarity from the first order to the third order in gearbox condition monitoring. To this objective, basic theories on cyclostationarity analysis for signal feature representation are reviewed. A fatigue test is carried out on a gearbox to obtain the gearbox signals of running-in stage, normal wearing stage and ultimate wearing stage. Based on the first-order cyclostationarity, the double-time synchronous averaging and the first-order cyclostationary spectrum is proposed for feature representation; the results of these approaches demonstrate their effectiveness in showing the gearbox condition degradation and even the gear structural fault. The spectrum of the second-order cyclic cumulant shows the degradation of the gearbox condition through the interactions between cyclic frequency and frequency. The cyclic bispectrum based on third-order cyclostationarity represents the gearbox condition degradation effectively through the interactions between frequencies. All the conclusions verify cyclostationarity analysis as an effective tool for gearbox condition monitoring.