Topological Imaging of Defects in Anisotropic Plates

Abstract : Topological imaging is an emerging ultrasonic imaging method based on two computations performed for the so-called reference medium. The reference medium should correspond as close as possible to the experimental medium in the absence of defects. The topological image will then highlight all the differences between the investigated experimental medium and the reference medium. The presented work aims at applying this method to the detection, location and imaging of defects in composite plates. If the propagation can be properly simulated and the associated experience performed, the defects of the medium can be imaged whatever the complexity of the propagation process. Wave propagation in composite plates is here computed considering an equivalent homogeneous anisotropic medium in the frequency regime. First a numerical experiment is presented. It consists in the investigation of a strongly anisotropic medium using two different wave modes simultaneously. Three defects are accurately located and imaged in the medium. Secondly, a real experiment is investigating an impacted quadratic composite plate is investigated with a single guided mode. Two impacts are well detected and located.