Integrity Monitoring of Right-Angle Structures Using Metamaterial Assisted Guided Wave Mode Discrimination

Abstract

This study proposes a novel method for structural integrity monitoring of right-angle structures, such as welded joints and T-profile panels, using ultrasonic guided waves. Firstly, building on the observed phenomenon of transmission and reflection selectivity of guided wave modes at geometric discontinuities, a framework for discontinuity detection is developed. Secondly, to address the issue of the damage-sensitive mode wave packets being immersed by other wave mode energy, a metamaterial-based mode selection design is proposed. The designed metasurface with a distinct bandgap selectively filters and amplifies certain guided wave mode (S0), making it feasible to recognize the signal caused by small-scale defects within a single measuring point. Thirdly, a testbench based on a T-shape aluminum profile is constructed, with the experimental results confirming the effectiveness of this approach in improving damage detection accuracy. By integrating the two predesigned damage index and introducing the Huber regression estimator, structural integrity can be evaluated precisely. The proposed framework contributes to advancing SHM techniques, particularly for structures with challenging geometries, by combining ultrasonic metamaterials with guided wave mode discrimination.