Modal Parameter Statistical Tdentification Based on Tmproved Random Decrement Technique and Wavelet Transform

This paper presents a new statistical identification method for modal parameter based on improved random decrement technique and wavelet transform. Improved random decrement technique can make a direct deal with zero mean non-stationary signals for free decay responses. The time- frequency characteristics of the wavelet transform can decouple dense frequency and low damping system. The bootstrap procedure is employed to evaluate and decrease the uncertainty of identification results. A complete theoretical derivation is proposed and a numerical example which is a four-degree-of-freedom system is used to illustrate the reliability of the proposed method. Compared with the traditional time-domain method and the wavelet transform only method, the presented method has higher recognition accuracy, especially for damping ratio coefficients.