A Lamb wave-based crack evaluation method in plate-like structures using specular reflections and tip diffractions

Abstract

Abstract The comprehensive assessment of crack angle, length and profile could provide an important reference for the non-destructive evaluation of plate-like structures. In this paper, we aim at fully exploiting information carried by reflections, so that details of the crack could be displayed as much as possible. Firstly, the Lamb wave reflections from a crack are classified into specular waves and tip diffractions. Under the linear assumption of crack profile, the specular waves could be regarded as being transmitted from the mirror point of the actuator with respect to the crack line, thus the corresponding reflection points can be located with geometric methods. On the other hand, diffractions are used to visualize crack tips where a fusion strategy is adopted to get the localization image. Both reflection points and tips are not only interpolated to show the crack position and profile, but also linearly fitted to display the crack trend for the estimation of its length and angle. Numerical investigations and experiments are carried out on different cracks, and related parameters are also discussed. Results show that the proposed method could make an accurate crack evaluation and reconstruct a detailed crack shape.