Crack orientation detection in plate-like structures via Lamb wave specular reflection analysis

Abstract

The determination of crack orientation plays an important role in the non-destructive evaluation (NDE) of plate-like structures. In this paper, the interaction between Lamb waves and cracks is investigated using the time domain spectral element method (SEM) as the simulation tool. On that basis, we analyse the geometric principle of specular reflections and propose an efficient crack angle detection algorithm. During the process, four sensors take turns to excite the Lamb wave which would result in twelve crack reflection signals. Using the corresponding actuator as the centre and the reflection length as the radius, we can obtain twelve reflection circles in total. When these reflections are specular, the mirror points of the actuators with respect to the crack line are exactly the intersection points of the circles. Thus, we can obtain the crack angle by this geometric relation. Validations on different cracks are made and the result of the algorithm shows a good agreement with the real value.