Nonstationary Vibration Signal Analysis Using Wavelet Based Time–Frequency Filter and Wigner–Ville Distribution

Abstract

Vibration responses of nonlinear or timevarying dynamical systems are always nonstationary. Time–frequency representation becomes a necessary approach to analysis such signals. In this paper, a nonstationary vibration analysis method based on continuous wavelet transform (CWT) and Wigner–Ville distribution (WVD) is presented. In order to avoid the crossterms in the original WVD, a time–frequency filter created by wavelet spectrum is employed to filter the time–frequency distribution (TFD). This process eliminates crossterms and maintains high time–frequency resolution. The improved WVD is applied to both simulated and practical timevarying systems. Bat echolocation signal, train wheel vibration, and bridge vibration under a moving train are used to assess the proposed method. Comparison results show that the improved WVD is free of crossterms, effective in identifying timevarying frequencies and is more accurate than the wavelet time–frequency spectrum.