Abstract
Abstract
Flexible manipulation of flexural waves is of great importance for structural vibration control and health monitoring. While existing tunable elastic metasurfaces for elastic wave manipulations primarily rely on mechanical reconfiguration, magnetic fields or shunting circuits, the potential of harnessing shape memory alloys (SMAs) to construct elastic metasurfaces remains an unexplored frontier. In this study, we propose a temperature-controlled switchable elastic metasurface (SwEM) composed of SMA pillars to function as an ON/OFF gating for flexural wave manipulation. This switching mechanism arises from the temperature-induced stiffness disparity inherent in martensite-austenite phase transition. Specifically, one thermal state is designed to provide the full 2π phase shift required for wavefront steering, actively turning the anomalous manipulation ON. Conversely, the alternate state yields limited phase variations that suppress anomalous reflection, effectively turning the functionality OFF. Numerical simulations and experimental validations demonstrate the on-demand activation and deactivation of anomalous reflection of flexural waves. This work presents a novel method for designing tunable elastic metasurfaces, offering prospects for programmable and smart elastic devices.