Lamb waves detection through phi-OTDR for structural health monitoring

In this paper, a distributed acoustic sensor based on phase-sensitive optical time-domain reflectometry (-OTDR) in optical fibers, for the detection of the Lamb waves generated by a piezo-ceramic actuator in an aluminum plate is investigated. It was observed that the distributed sensor can distinguish the arrival of the Lamb waves in different portions of the sensing fiber and detect the changes of the Lamb waves due to defects. The proposed approach can find application in simultaneous strain/acoustic monitoring, as well as in the development of Lamb waves based structural health monitoring (SHM) systems capable to compensate the undesired effects of operative and environmental conditions.