In this paper, an analytical framework to analyze the scattering of an incident ultrasonic Rayleigh wave at a delamination-like discontinuity located near the surface of a thick plate is developed. It is assumed that the waves are generated and received using a pitch-catch setup, in which a pair of movable transducers is placed on the surface of the plate. It can be shown that the incident Rayleigh wave is converted into Lamb waves propagating in the thin layer above the defect, and a Rayleigh wave propagating below it. The Rayleigh to Lamb wave conversion at the delamination is quantified in terms of the scattering coefficients. The results from the analytical solutions are compared with those from numerical simulations for a thick aluminum plate, revealing good agreement between them.
doi: 10.12783/SHM2015/225