Deflecting flexural wave with high transmission by using pillared elastic metasurface

This paper proposes an innovative and simple elastic metasurface, which is one kind of ultrathin metamaterial, to abnormally deflect normally and obliquely incident flexural waves. In particular, negative refraction of flexural wave is also realized. The proposed metasurface can support high transmission and full phase control for transmitted waves. The metasurface is composed of three-dimensional (3D) functional units which are combined with multiple slender pillars for phase shift accumulation. The slots are filled in the 3D functional units to avoid coupling between adjacent functional units. Firstly, based on the generalized Snell's law, the metasurface in the sub-wavelength regime is theoretically designed. Secondly, the deflecting functionality of the metasurface for incident flexural waves is numerically demonstrated. Finally, the deflecting functionality is verified by the corresponding experiments. The proposed metasurface has a great application potential in many fields, such as ultrasonic detection, energy harvesting, and vibration control.