Multi-Path Exploitation In A Sparse Reconstruction Approach To Lamb Wave Based Structural Health Monitoring

In guided-wave structural health monitoring, the multipath reflections due to target interactions with the plate boundaries have typically been avoided. This has been accomplished either by examining only the interior regions of the plate under test, whereby boundary reflections arrive outside the considered time window, or through application of dampening clay, to the boundaries that renders the amplitude of the multipath reflections negligible. While both methods are successful, they fail to represent a robust realistic scenario, and ignore the potentially beneficial contributions of multipath. This paper proposes a multipath exploitation scheme for defect localization in guided Lamb wave structural health monitoring under the sparse reconstruction framework. More specifically, a single-mode Lamb wave based signal model, which accounts for both multipath reflections and the direct target scatterings, is inverted via group sparse reconstruction. Performance validation of the proposed defect localization scheme is provided using simulated data for an aluminum plate.