A comprehensive study of non-destructive localization of structural features in metal plates using single and multimodal Lamb wave excitations

Metal plate structures, crucial components in various industrial sectors, demand meticulous inspection methods for the maintenance of their structural integrity. This review article not only serves as a contemporary introduction to this research field but also underlines the vital role of this field in ensuring the safety and reliability of these structures. The study delves into Lamb wave generation and detection techniques, highlighting the challenges and advancements in transducer technologies. Two detailed case studies are presented to contextualize and illustrate the practical applications of these techniques. The first case study demonstrates the detection of weld joints and stiffeners in steel plates, particularly relevant to the shipbuilding industry. Through a combination of numerical simulations and experimental validations designed for this narrative, this study highlights the capability of the A0 Lamb wave mode in identifying these features. The second case study, equally supported by new experiments, focuses on detecting thickness reductions in aluminum plates using high-order Lamb modes in a multimodal excitation setup. This scenario simulates conditions such as corrosion or wear that induce material thinning. By creating blind holes of varying depths on one side of the plate and conducting inspections from the opposite side, the study demonstrates the method’s precision in identifying hidden defects. The case studies involving aluminum and steel specimens exemplify the efficacy of Lamb waves in the nondestructive evaluation of metal plates. They provide critical insights into the method’s ability to deliver precise and efficient detection of structural anomalies despite inherent challenges in signal interpretation and analysis.