Compressive sensing for damage detection in composite aircraft wings

This work deals with an ultrasonic guided wave structural health monitoring (SHM) system for composite aircraft wing damage inspection. The main idea is to use piezoelectric discs bonded to various parts of the aircraft wing, in a form of relatively sparse arrays, to generate and receive ultrasonic guided waves aimed at detecting defects. The development of a structural monitoring system able to inspect large composite structures and to communicate remotely to the central unit is challenging due to both the huge number of piezoelectric sensors needed and the high sampling frequency of the recorded signals. To address this problem, here a low rate sampling system has been developed by using a modified version of Compressive Sensing (CS) technique that exploits the sparse representation of dispersive and anisotropic ultrasonic guided waves in the frequency warped basis. The CS framework is applied to lower the sampling frequency and to enhance defect localization performances in composite material through the analysis of anisotropic guided waves propagation. The approach is based on the inverse Warped Frequency Transform (WFT) as the sparsifying basis for the CS acquisition and to compensate the dispersive behavior of guided waves for several different directions of propagation. As a result, an automatic detection procedure to locate defect-induced reflections has been successfully tested on Comsol software simulated guided waves propagating in an composite wing specimen.