Wavelet based mode shape analysis for damage detection

Abstract

Many authors have proposed wavelet analysis as an efficient and useful numerical tool for damage detection in structures. Some of these proposals consist of the application of the wavelet analysis to the mode shapes of the structure in order to detect perturbations induced by damage. Some authors have proposed the so-called hybrid methods, in which the wavelet analysis is applied to the spatial evolution of a modal damage detection parameter. With these hybrid methods, the ability of the wavelet analysis to detect singularities and variations of a signal is used to enhance the sensitivity of the damage detection parameter. This paper presents a hybrid method based on the variation of mode shapes weighted with the variation of their natural frequencies due to the presence of damage. A Continuous Wavelet Transform is applied to each of the weighted mode shape difference between the undamaged and the damaged state, and the corresponding coefficients for each mode shape are added up. The paper includes an experimental analysis of the sensitivity of the method for a steel beam. © The Society for Experimental Mechanics, Inc. 2012.