This paper presents a guided wave based global-local sensing method for rapid detection and quantification of multi-site delamination damage in large composite panels. The global-local approach uses a hybrid system consisting of a piezoelectric transducer (PZT) for generating guided waves and a non-contact scanning laser Doppler vibrometer (SLDV) for acquiring guided wave data. The global-local method is performed in two steps. First, a phased array configured of a small number of SLDV scan points (for example 10×10 points in a rectangular grid array) performs inspection over the entire plate to detect and locate damage. Local areas are identified as potential damage regions for the second step. Then high density wavefield measurements are taken over the identified areas and wavefield analysis is performed to quantitatively evaluate the damage. For the proof of concept in case with multi-site damage, the global-local approach is demonstrated on a carbon fiber reinforced polymer (CFRP) composite plate with two sites of impact-induced delamination damage. In the first step, the locations of two delamination sites are detected by the phased array method. In the second step, the delamination size and shape are evaluated using wavefield analysis. The detected delamination location, size and shape agree well with those of ultrasonic C-scan and the method led to a 93% reduction in inspection time compared to a full SLDV dense grid scan.
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