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Boundary echo control of S0-mode lamb waves using gradient phononic crystals
Haoming Hu1, Hongyu Cui1, Xiaokai Yin1
1School of Naval Architecture & Ocean Engineering, Dalian University of Technology, No.2 Linggong Road, Ganjingzi District, Dalian City, Liaoning Province, People's Republic of China.
Abstract:
Large-amplitude boundary reflections of S0-mode Lamb waves significantly impede the accuracy of ultrasonic nondestructive testing. This study proposes a phononic-crystal-based approach for S0-mode boundary echo control. By integrating a frame into a resin-steel phononic crystal (RSPC) unit cell, a triangular-frame phononic crystal (TPC) is designed for echo suppression. Numerical simulations confirm that the proposed structure effectively attenuates boundary echoes. Furthermore, a gradient TPC is developed to enhance control performance through spatially varying configurations. Band structure analysis reveals that the amplitude suppression of boundary echoes originates from the conversion of propagating waves into modes dominated by the vibration of the integrated resonators. Experimental results demonstrate that the gradient TPC significantly outperforms conventional damping clay in suppressing boundary reflections. The proposed method holds potential for advancing ultrasonic guided-wave-based structural health monitoring.
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