Non-Destructive Testing (NDT) is one of the major requirements in aerospace structural design. Appropriate use of NDT guarantees safety in aerospace and is thus a subject of highest attention. In this study, a new model-based NDT method is proposed for damage identification. The computational inverse problem of identifying a scatterer in a time-dependent wave field is considered. The wave speed of the background medium and the wave source are assumed to be known. Wave measurements, possibly noisy, are given at chosen discrete points in space (sensor locations) and time. The goal is to find scatterer parameters such as location, size and shape. The computational solution procedure consists of two steps. In the first step, a standard fast Arrival-Time Imaging (ATI) algorithm is employed. This results in a rough image which provides possible regions for the location of the scatterer. In the second step an optimization scheme based on Time Reversal (TR) is used to determine the location, size and shape of the scatterer.
Next, a comparison between combined ATI-TR and the well-known Full Waveform Inversion (FWI) method, using the adjoint method as an efficient way to advance toward the real scatterer parameters, is discussed. The goal of this study is to compare the performances of these methods with a focus on running time, amount of data required and identification capabilities.
