Compressive laser scanning with full steady state wavefield for structural damage detection

Abstract

This paper presents a compressive sensing-based high speed full-field laser scanning for structural damage detection. Conventional full-field laser scanning techniques with a high resolution spatial sampling rate are time and energy consuming to process the vast amount of data for large-scale inspection. To address this issue, a compressive full-field ultrasonic laser scanning is proposed in this study. In this technique, 2D random scanning patterns are used for compressive sensing in the inspection range of a laser scanning system. Random steady state ultrasonic responses are obtained by a Laser Doppler Vibrometer and a mirror tilting device with a single fixed frequency excitation by a mounted piezoelectric transducer. After the measurements are completed, a narrow bandwidth filter is applied to the compressed steady sate wavefield data to extract the steady state response at the excitation frequency using discrete Fourier transform (DFT). The full steady state response is reconstructed by using a Yall 1 algorithm which is a L1-minimization solver. Wavenumber based damage visualization techniques are then employed to estimate the damage sizes. For the performance evaluation, several simulation and experimental investigations are performed on aluminum and composite plates, which contain various types of damage, including corrosion and delamination. The results demonstrate that the proposed laser scanning technique based on compressive sensing could increase the efficiency of the damage detection and visualization process with high accuracy.