Locally Resonant Materials for energy harvesting at small scale.

This paper aims to report and analyze the possibility of focusing the mechanical energy carried by anti-plane shear waves, localizing it inside a resonant cavity. The transmission through a pair of identical barriers, constituted by two-dimensional (2-D), two-phase Locally Resonant Metamaterials (LRMs) and separated by the cavity itself, is here considered. Elastic waves at frequencies inside the LRMs band-gap are subjected to an attenuation which can trap them inside the cavity, enhancing its motion and concentrating the related vibration energy. LRMs behavior is characterized by applying an asymptotic homogenization technique, able to explicitly compute their effective properties. The behavior of the studied system is then analytically analyzed with the goal of optimizing the geometry to enhance the enrgy concentration. An example is finally shown.