Dual-functional pentamode metamaterial with water-like and topological transmission properties

In this paper, a water-like pentamode metamaterial (PM) with a single metallic material is designed and the topological edge-state transmission properties of elastic waves in the PM are thoroughly investigated. Numerical results indicate that by introducing structural perturbation into PM, the Dirac point degeneracy atK-point can be opened and topological band inversion can be generated. Topological edge states are also obtained by organizing PM structural units, which are robust to defects such as bending and cavities. In addition, it also has the mimics water in acoustic properties over a wide frequency range, i.e. it exhibits transparency when surrounded by water. Therefore, it will have both good transmission efficiency and acoustic stealth performance when used as an underwater waveguide. The dual-functional PM proposed in this study provides theoretical guidance for designing underwater stealth acoustic waveguides.