Lamb Wave Near-Field Source Localization Method for Corrosion Monitoring

Corrosion is one of the main causes of aircraft structural damage. The deepening of the corrosion depth will greatly endanger the safety of the crew. The Lamb wave array signal processing method can be used to estimate the direction of arrival (DOA) of the signal source. As a form of the Lamb wave array signal processing method, multiple-signal classification (MUSIC) has been gradually applied to the corrosion monitoring of aluminum plates. However, when MUSIC is used for Lamb wave DOA estimation, it has a low resolution and poor anti-interference ability. To improve it, the Lamb wave near-field source location (LWNFL) method is proposed in this paper. The new method adopts a double-sensor array arrangement. Firstly, the compressed sensing (CS) theory is combined with the Lamb wave near-field array model to obtain a DOA estimation of the corrosion. Here, the corrosion angle can be obtained using a CS reconstruction algorithm, and the noise interference can be suppressed by limiting a minimization of the l2 norm. Then, the corrosion distance is calculated according to the Lamb wave arrival time difference between different sensors. Finally, the average of the positioning results from multiple excitation sensors is used as the final location of the corrosion. The proposed LWNFL method is verified on an aluminum plate. The experimental results show that the new method can accurately obtain the location of corrosion and has good resolution and strong anti-interference ability.