Accepted Monday Jun 15, 2009
Control of waves with metamaterials is of great topical interest, and is fueled by rapid progress in broadband acoustic and electromagnetic cloaks. However, when one moves into the area of elastodynamics, it is no longer possible to design cloaks using conformal mappings. We propose a design for a cloak to control bending waves propagating in isotropic heterogeneous thin-plates. This is achieved through homogenization of a multilayered concentric coating filled with piecewise constant isotropic elastic material. Importantly, our cloak displays no phase-shift for both backward and forward scattering. To foster experimental efforts, we finally provide a simplified design of the cloak which is shown to work in more than two octaves frequency range (30 Hz to 150 Hz) when it consits of 10 layers using only 6 differents materials overall. This metamaterial should be easy to manufacture, with potential applications ranging from car industry to anti-earthquake passive systems for smart buildings, depending upon the plate dimensions and wavelengths.