Realizable Elastic Wave Cloaking in Mechanical Metamaterials

Cloaking, the tailoring of wave refraction to simultaneously shield an object from waves and prevent scattering, has proven to be a powerful conceptual tool for wave control. By employing optical or acoustic metamaterials, cloaking designs of various degrees of approximation have been conceived and experimentally verified. Elastic waves, on the other hand, have proven harder to cloak. In particular, the materials necessary for an ideal elastic wave cloak must break the minor symmetry of the elasticity tensor, an effect which has not been achieved in any known material or metamaterial. We present a means of circumventing this dilemma to design a symmetrized elastic wave cloak. We demonstrate that this cloak can effectively control waves for most realistic conditions while simultaneously preserving the symmetries found in real materials.