Finite elastic metasurface attachment for flexural vibration amplification

In this study, we propose a compact elastic metasurface structure that confines and amplifies flexural vibration energy over an internal local area. The proposed structure utilizes the well-known internal wave trapping mechanism of metasurfaces, developed for an incident wave beyond the critical angle. Our novel method is the first to optimize the metasurface structure for wave energy amplification and to realize a metasurface structure in practical attachment form with a finite compact dimension. These aspects clearly distinguish the proposed metasurface structure from conventional structures, which have mainly been developed for wave energy dissipation and are typically realized in an unpractical form. The proposed metasurface structure can be divided into three finite regions in terms of role: metasurface, phase-matching, and attaching regions. We validated our proposed metasurface through experiments whose results show an amplification of the input flexural vibration amplitude of more than twenty times. This drastic amplification was achieved by the intrinsic negligible damping characteristic of the pro-posed simple metallic structure. In this study, the detailed working physics of the proposed structure and the physical significance of the constituents are thoroughly addressed with nu-merical simulations.