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 0–2 π 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.