Identification of multiple damage using modal rotation obtained with shearography and undecimated wavelet transform

Due to its high spatial resolution measurements and flexible and contactless experimental setup, shearography, as a non-destructive testing technique, provides effective structural damage identifications. However, this effectiveness can be increased by applying post-processing algorithms to experimentally measured modal rotation fields. In this paper, the authors present a novel method, consisting of shearographic non-destructive testing and 2D undecimated wavelet transform as a post-processing tool. The studies covered tests of the proposed method on simulated modal data of a damaged plate, as well as a validation on real data obtained from shearographic experiments. The results show the high sensitivity of the proposed method to either single or multiple damage, including its edges and its various configurations.