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

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.

Effective Boundary Conditions and Stochastic Crack Distribution for Modelling Guided Waves Scattering by a Partially Closed Interfacial Delamination in a Laminate

“…To reduce the computational costs, an effective model is proposed and validated here for in-plane problems, but the approaches can be applied and developed for the three-dimensional problems employing relations for spring stiffnesses derived by Lekesiz et al [ 39 ], Golub and Doroshenko [ 40 ], Lekesiz et al [ 66 ], Golub et al [ 67 ]. Thus, Zhang et al [ 68 ] proposed an ultrasonic method providing an accurate crack evaluation and reconstructing a shape of an open crack and the employment of such procedures along with the EBCSs might be further extended to be also efficient for the identification of bridged cracks and zones with imperfect contact.…”