Lamb wave-based nondestructive testing techniques are gaining attention. However, the complex propagation of Lamb waves in tapered plates makes traditional methods inadequate. This paper presents a damage localization imaging method based on an ultrasonic guided wave delay superposition algorithm. Firstly, a finite element model of a linearly varying inclined plate with variable thickness was established to investigate the propagation mechanisms of guided waves and their interactions with defects. Subsequently, a method combining dispersion curves, which vary with thickness under single central frequency excitation, with a delay superposition algorithm was proposed for detecting thickness-related defects. Finally, the effectiveness of the proposed method was validated through finite element simulations, and further experimental verification was conducted to confirm the feasibility of signal excitation, narrowband extraction, and damage imaging. The results demonstrate the accuracy of this method in identifying defects in variable thickness plates. Experimental verification in signal excitation, narrowband extraction, and damage imaging further supports the method's effectiveness in identifying defects in variable thickness plates, resulting in accurate damage imaging.

Lamb wave,Variable thickness plate,Asymmetric propagation,Dispersion compensation,Damage imaging