Detection of a Through-Thickness Crack Based on Elastic Wave Scattering in Plates, Part II: Inverse Solution

In the first part of the present paper, a numerical method called spectral finite elementmethod (SFEM) is presented. As shown there, SFEM offered a promising performance insimulating wave scattering phenomena in plates, with less computational effort whileobtaining the highest resolution. The forward solution of wave scattering phenomenon based on the differential waveform of highest resolution plays a crucial role for detection of through-thickness crack in plates, as an inverse problem. Therefore, the results of the first part of the paper have been used in the second present part, in which a novel approach in wave scattering based crack detection, according to the concept of Time Delay (Differences) Of Arrival (TDOA) has been presented. In the past decades, TDOA and its related concepts have been applied generally on the problem of localization and pursuing sound sources in robotics, electronics engineering, control engineering, and so on. However, in this study TDOA is employed for crack detection problems for the first time. Introducing TDOA has provided a robust algorithm for crack detection which is highly sensitive to the crack location and size. Using the proposed algorithm, a couple of numerical case studies has been studied, in which the predicted crack location and dimensions are quite encouraging.