Damage localization in composite plates that exploits edge-reflected Lamb waves

Lamb waves can travel a relatively long distance in the plate-like structures. Reflection and scattering may occur when they arrive at an obstacle, and the associated wave packets may contain the information about the obstacle and the whole path they travel through. Those extra reflections change the direction once they meet an obstacle, which enlarges the monitoring zone and enriches the inspecting directions. The motivation and objective of this paper is to exploit the information included in these reflections for damage identification. Firstly, dispersion compensation is applied to the residual between the measured signal and the pre-recorded baseline. Thus the propagation distance of each scattered wave packet could be estimated. On this basis, the sparse reconstruction algorithm is modified to adapt to both direct-scattered waves and indirect-scattered waves for damage identification. Two experimental examples are conducted on CFRP laminates, where damage is correctly identified with the minimum sensor array consisting of one transmitter and one receiver.