Nonstationary time-frequency analysis for machine condition monitoring

In this paper, three main time-frequency/time-scale (TF/TS) analysis algorithms: windowed Fourier transform (WFT); Wigner-Ville distribution (WFD); and wavelet analysis (WA), have been studied and implemented. The authors compare these algorithms using an identical set of synthetic signals, from which one can realize their individual features. To justify the effectiveness and to highlight the importance of using TF/TS analysis, two experimental case studies have been conducted and investigated. One is the vibratory analysis of a robot motor with gear transmission noise and the other is the investigation of nonstationary phenomena of a rotor dynamics system with both an electromechanical clutch and brake.