Interaction of Lamb Waves with a Notch in a Bent Plate

The application of guided waves for the non-destructive evaluation of thin plates has been explored extensively for the last two decades. However, many industrial applications utilize thin plates containing one or more bends in them. Investigation of Lamb wave scattering from such bent plates, specifically in the presence of defects such as notches, cracks, etc., is still an open problem. In this regard, the analysis of interactions of fundamental Lamb waves with a V-shaped notch located inside a bent portion of a metallic plate is presented. The investigation is carried out by employing an efficient hybrid numerical framework comprising semi-analytical finite elements (SAFEs) together with high conventional finite elements. While SAFEs are used to model wave propagation through defect-free plates on either side of the plate bend, finite elements are used to model the bent portion containing the notch. The effect of depth and location of the notch on the scattering behavior is analyzed over a span of frequency of interrogation signal and for incidence of both fundamental modes. The sensitivity of scattered waves with the notch parameters is observed to change substantially with the change in notch location and interrogation signal parameters. The inferences presented can prove instrumental in devising a strategy for detecting and characterizing a notch located inside a plate bend.