Method for improving the accuracy of damage signal recognition based on the thickness-graded additional structure

During S0 mode Lamb wave-based damage identification, structural boundary echoes significantly degrade localization accuracy. This study proposes a solution involving a thickness-gradient additional structure (TGAS) to control such S0 mode Lamb wave boundary echoes. Numerical simulations reveal that the additional structure achieves favorable boundary echo control across a wide frequency range. By analyzing the dispersion curves of variable-thickness plates, displacement responses and power flow, the mechanisms of boundary echo suppression are elucidated. An additional structure model is fabricated using wire-cutting technology, and experimental validation confirms the effective control of S0 mode Lamb wave boundary echoes by the additional structure, with a control effect significantly superior to that of clay.