Non-singular three-dimensional arbitrarily shaped acoustic cloaks composed of homogeneous parts

Abstract

Acoustic metamaterials are artificial materials with unique acoustic properties, permitting interesting behaviors, such as acoustic cloaking. Acoustic cloaks can make an object appear acoustically “invisible.” Prior cloaks that were designed based on transformation methods have been limited by inhomogeneous, anisotropic, and extreme material parameters. In this paper, a multistep transformation is proposed for a general tetrahedron. Each tetrahedron contains three homogeneous parts. Since most cloaks can be approximated as polyhedra, they can be divided into a series of tetrahedra. As a result, most of the 3D cloaks can be constructed of homogeneous parts by first approximating them as polyhedra. Two examples of the polyhedral cloaks are given, which are simulated using COMSOL Multiphysics finite element software. The results show that the cloaks work well at acoustically concealing 3D objects. Although the properties of each part are non-singular, a balance is still required between cloaking performance and moderation of the material property values.