A damage index for structural health monitoring based on the empirical mode decomposition

This paper presents two novel damage indices based on empirical mode decomposition (EMD) and fast Fourier integration for identifying structural damage caused by a change in structural stiffness. The paper also demonstrates the effectiveness of the proposed damage indices formulated based on a series of coupled mathematical/engineering approaches that are used to detect damage in pipes reliably and accurately. The main approach is based on monitoring the vibration response of pipes using piezoelectric sensors and the first intrinsic mode functions (IMFs). Finite element analysis is used to simulate the response of a healthy pipe, as well as pipes with various sizes of damage. Damages are meant to represent the outcome of local corrosion (damage) with varying reduction in areas around the circumference of the pipe. The evaluated damage indices could effectively establish the location of the defects. Moreover, the evaluated energy indices could also distinguish various size defects. To demonstrate further the effectiveness of our proposed damage indices, the results are compared with other effective indices based on wavelet packet and other statistical methods reported in the literature.