47. Experimental Investigation on Aluminum Plate Damage Monitoring Based on Acoustic–Ultrasonic Technique

It is important to monitor the condition and detect the damage of structures in order to insure aviation equipment safety and reduce maintenance cost. For damage monitoring of aircraft structures, elastic wave propagation approach is briefly discussed, in which the acoustic–ultrasonic technique can be used to identify the additional reflections generated from seeded cracks. In this article, based on acoustic–ultrasonic technique, theoretical and experimental studies are performed to explore the characteristics of the Lamb wave produced in the aluminum plate for aeronautic use. Various comparing experiments and theoretical studies are performed on the aluminum plates with and without artificial crack damage. Mainly, short-time-root-mean-square (STRMS) method and wavelet reassigned scalogram analysis are applied to investigate the propagation and time-frequency characteristics of the Lamb wave. By analyzing the features of corresponding Lamb wave signals, the qualitative damage identification method is developed. And this work provides technical support for the innovation of maintenance pattern from time-based maintenance to condition-based model.