LAUSR

Pentamode materials (PMs) are engineered isotropic or anisotropic elastic structures that mimic the acoustic behavior of ideal fluids. Recently, many applications such as negative refraction lens, focal lens, and a cloak have been designed and demonstrated using 2D PMs. We consider metallic lattice structures in which only one wave mode propagates over a wide frequency band. Unlike the 2D PM which naturally has a boundary, the three dimensional PM needs to be sealed to isolate the interior structure from water. However, the material used for encapsulation alters the effective surface impedance of the material. In this talk, we present 3D PMs with acoustic properties matched to water and show that the transmission is sensitive to the thickness of the boundary plate. An analytic model is established to provide some insights into the boundary transmission. Iterations were performed in FEM simulations to achieve optimal transmission within the frequency range of interest (4 kHz–10 kHz). The model PM with part...