Hierarchical Energy Distribution-Based Lamb Wave Tomography for Damage Localization in Multilayer Heterogeneous Metallic Bonded Structures

As the core component of key equipment in the fields of aerospace, military, and advanced energy, the multilayer heterogeneous metal-bonded structures (MLHMBSs) are required to serve for a long time in harsh environments such as extreme temperature and stress. Detecting potential damages in MLHMBS is crucial to ensure the reliability of key equipment and prevent further catastrophic accidents. In this regard, a major category of nondestructive testing techniques based on ultrasonic guided waves has gained increasing popularity for damage evaluation of various industrial structures. Despite this, it remains an ongoing challenge to inspect MLHMBS using ultrasonic guided waves due to the complicated wave propagation characteristics induced by the serious impedance mismatch within the multilayer heterogeneous structures. To address this problem, a reconstruction algorithm for probabilistic inspection of defects (RAPID) based on the hierarchical energy distribution is proposed to detect and locate the defects of MLHMBS. Compared with the previous traditional energy-based damage index (DI), the method proposed in this article enhances the response of defects in the structure to the DI and effectively avoids missed and erroneous defect detection because it takes into account the uneven energy distribution between layers and the energy distribution law of the frequency band. From the validation experiments, the proposed approach enables precise damage localization in MLHMBS using Lamb waves, promoting the preferable performance of ultrasonic guided wave techniques in practical industrial applications.