Wavelet Based Structure Damage Detection

In structural health monitoring (SHM), the Fourier transform (FT) is a classical tool for spectrum estimation. Because of the low sensitivity of the FT to local structural damages, the wavelet packet transform (WPT) is used. The WPT describes the signal in a localized time (or space) and frequency (or scale) domain and a level-by-level decomposition of the signal is obtained. Then, the energy distribution of the signals at the bottom of the WPT decomposition tree can be used to identify changes in energy between frequency bands, a behavior that can be associated with damage in the structure. The validation of this theory is obtained with a finite element model (FEM) of a simply supported beam implemented in Matlabreg.