Flexible regulation for broadband of flexural wave by solid-liquid reconfigurable metastructure

Abstract Metastructures have shown good application prospects in wavefront manipulation. By studying the reconfigurable characteristics of metastructure, the great potential of metastructures in the multi-functional flexible control of flexural waves can be revealed.In this paper, a broadband flexible reconfigurable elastic solid-liquid-type metastructure is proposed. By filling cylindrical cavities with different volumes of liquid, the flexural wave band structure of the solid-liquid metastructure unit cell is regulated. Based on the functional relationship between the flexural wave frequency dispersion curve and the phase, the 0-2p accurate phase change of the flexural wave over a broadband range is realized. The design of subwavelength elastic metastructure based on the generalized Snell's law realizes the specified angular refraction of flexural waves over a wide range of frequencies without the need to remanufacture the metastructure. In addition, based on the bandgap properties of metamaterials, a metastructure for bidirectional selective transmission of flexural waves is designed. Finally, by changing the height of the liquid surface, the multiple functions of the solid-liquid reconfigurable metastructure in beam focusing and the phenomenon of generating non-diffracting Bessel beam are demonstrated. And when focusing the beam, we find a phenomenon, which uses a fixed phase profile to achieve flexural wave focusing at different frequencies. The reconfigurable solid-liquid type metastructure proposed in this paper provide a modulation for the active regulating of elastic flexural waves within a wide range of frequency, and provides a new idea for the development of reconfigurable elastic metastructure.