A review of time-frequency methods for structural vibration analysis

This paper presents a review of time-frequency distribution tools for the analysis of non-linear vibrations of structures. The theoretical basis of the moving window discrete Fourier transform (DFT), the moving window auto-regressive (AR) model, the harmonic wavelet transform, the Wigner-Ville (WV) and the Windowed Wigner-Ville (WWV) bilinear distributions are presented. The strengths and weaknesses of each technique are demonstrated by applying them to a variety of synthetic signals. Then the methods are applied to real vibration data taken from experiments on a damaged reinforced concrete beam. It is shown that, for this simple structure, the DFT and AR moving window, wavelet and WWV methods give similar estimates of the time-frequency relationship for the fundamental mode, though the AR model estimate is much noisier than the others. (C) 2003 Elsevier Science Ltd. All rights reserved.