Harnessing fluid pre-pressure to tune the properties of phononic crystals

Abstract Phononic crystals and acoustic metamaterials have shown great potential in many applications. The fluid has been used to made phononic crystals with special properties. However, few research has investigated the influence of fluid pre-pressure. In this paper, we investigated the influence of fluid pre-pressure on the properties of phononic crystals and elastic metamaterials made of fluid and hyperelastic solids. The pre-pressure in the fluid can change the geometry, density, degree of anisotropy and stiffness of the phononic crystals, and thus influence the wave propagation behaviors. The results show that the pre-pressure can significantly expand the bandgaps of phononic crystals and acoustic metamaterials, and can even create new bandgaps in some cases. The band structures and bandgaps can be continuously tuned in real time. Moreover, we also investigated the mechanism of how the changing factors influence the band structures. The results indicate that the geometry change and the stiffening effect play major roles in expanding the bandgaps.