A new structural damage detection index based on analyzing vibration modes by the wavelet transform

Abstract

A study was conducted to demonstrate a new new structural damage detection index based on analyzing vibration modes by the wavelet transform (WT). The performance of the method is demonstrated by the first three vibration modes of a simply supported (SS) beam. The damaged vibration mode (DM) was assumed to be composed of undamaged mode (UM) and other components, such as damage-induced variations and noise. The DM is extended by its asymmetry to reduce border distortion. This was achieved by 'wextend' command in MATLAB environment and the extended signal was upsampled to the nearest power of 2 by cubic spline the DWT was interpolation, as the defined for a sequence with length of some power of 2. The method was applied to the first three vibration modes of a beam with length L = 1 m and section sizes 40(width) × 30(height)mm2.