Reconfigurable flexural waves manipulation by broadband elastic metasurface

Abstract

We propose a reconfigurable elastic metasurface for broadband plate wave control where the flexural-dominated plate mode is concerned. The structure consists of a plate with nuts and screws perpendicular to the plate. With the continuous changes of nut positions on the screws, the phase shift can cover 2π span with high transmittance over broadband frequency. The mechanism of the tunability of phase shift caused by the screw-in depth is discussed based on the dispersion theory of local resonant phononic crystals. Then, subwavelength elastic metasurfaces are designed based on the generalized Snell’s law demonstrating numerically and experimentally abnormal refraction and wave focusing functionalities without remanufacturing the metasurface. Furthermore, we show asymmetric transmission with a structure containing two parallel metasurfaces. Different functionalities can be achieved by changing the screw-in depth at different frequencies. The proposed metasurface designs could provide a novel and feasible route to control flexural waves in broadband frequency range and take a critical step in the pragmatic development of elastic metasurfaces.