Metamaterial structures with periodic local resonances

Vibration characteristics of metamaterial structures manufactured of assemblies of periodic cells with built-in local resonances are presented. Each cell consists of a base structure provided with cavities filled by a viscoelastic membrane that supports a small mass to form a source of local resonance. This class of metamaterial structures exhibits unique band gap behavior extending to very low frequency ranges. This work presents a physical realization of this class of metamaterials in the form of beams and plates with periodic local resonances. A finite element model (FEM) is developed to predict the modal, frequency response, and band gap characteristics of different configurations of the developed metamaterial structures. The model is exercised to demonstrate the structures' band gap and mechanical filtering capabilities. The predictions of the FEM are validated experimentally when the structures are subjected to excitations ranging between 10-5000Hz. It is observed that there is excellent agreement between the theoretical predictions and the experimental results for plain structures, structures with cavities, and structures with cavities provided with local resonant sources. The obtained results emphasize the potential of the metamaterial beams and plates with periodic local resonances for providing significant vibration attenuation and exhibiting band gaps extending to low frequencies. Such characteristics indicate that metamaterial structures are more effective in attenuating and filtering low frequency structural vibrations than plain periodic structures of similar size and weight.