Baseline-free damage detection in composite plates using edge-reflected Lamb waves

Abstract

This paper presents a baseline-free damage detection method which leverages the multipath reflected Lamb waves for structural prognosis. From the viewpoint of ray tracing, the reflection of a propagating wave at a free edge is considered as a virtual transducer sitting at the mirrored location of the actual one, injecting excitation into the structure, or recording Lamb waves traveling from the source. These extra echoes arise waves that inspect the structure from different directions, which is equivalent to adding sensing paths into the sensor network. On this basis, the reciprocity breaking effects of each sensing path is quantitatively evaluated by measuring the waveform differences of the associated wave packets in the two response signals that recorded before and after the transmitter and receiver exchange their roles. Note that the indirect sensing paths related to edge reflections consist of several segments. The probabilistic imaging method is modified to accommodate both direct and indirect paths. The proposed multipath Lamb wave imaging algorithm is validated using an experiment conducted on a composite plate with simulated damages. The results demonstrate its availability and effectiveness, i.e., damage detection and localization is achieved using a single transmitter–receiver pair.