Advancements on the Inspection of Underwater Plates by Means of Guided Waves

Abstract

This paper presents the results of an experimental study where guided ultrasonic waves (GUWs) are used for the structural health monitoring / nondestructive evaluation of immersed plates. The method hypothesizes the generation of leaky Lamb waves by means of laser pulses and their detection by an array of immersion transducers. The signals are processed using continuous wavelet transform to extract few damage-sensitive features. These features are then used to an outlier analysis problem and to a probabilistic approach to create an image of the plate in search for possible structural anomalies. In the study presented in this paper, an automatic smart scan system designed and built at the University of Pittsburgh is employed to inspect underwater plates reliably and repeatedly. The time waveforms associated with all the laser-irradiated point to sensor paths are processed using the algorithms proposed here. The results indicate promise and future studies should focus on the generalization of the methodology.