Wideband Dispersion Reversal based Corrosion Inspection Using A0 Mode Lamb Waves

Ultrasonic guided waves have been used for nondestructive testing and structural health monitoring. However, traditional methods are usually hindered by the dispersion feature of the guided waves, where difficulties such as ambiguous interpretation of multimodal signals arise, resulting in baseline-dependency or narrowness of bandwidth. To overcome such obstacles, a baseline-free corrosion inspection method base on wideband dispersion reversal (WDR) of single mode Lamb wave is introduced. Pre-dispersive excitation is designed according to the WDR technique, so that self-compensation is expected for an intact path. Dual side excitation is adopted for selective generating A0 mode Lamb waves. The corrosion inspection is achieved based on the time-frequency index (TFI). The performances of the proposed method are validated through a simulation study on an aluminum plate.