A piezoelectric-nonreciprocal metamaterial with shaped eigenvectors using shunted piezo-networks

This paper presents a class of passive nonreciprocal metamaterials (PNMM) which are designed to control the flow of acoustic waves along a one-dimensional periodic acoustic duct. The proposed PNMM consists of a multi-cell array of acoustic cavities which are provided with piezoelectric boundaries. These boundaries are connected to an optimally designed array of shunted inductive networks in order to spatially shape the eigenvectors of the array in such a manner that breaks the reciprocity of the acoustic duct. This approach distinguishes itself from other approaches where non-reciprocities are controlled either actively or passively . A finite element model (FEM) is developed to analyze and predict the dynamic characteristics and behavior of the proposed PNMM for various shunting strategies and distributions of the networks. The predictions of the FEM are validated experimentally using a five-cell array that is tested using the Transmission Loss and Impedance tube of ACUPRO (Sage Technologies). In the experimental model, the inductances are synthesized electronically to enable significant tailoring of the eigenvectors of the PNMM. The obtained results indicate significant breaking of the non-reciprocity when the characteristics of the PNMM are determined during forward and backward wave propagations.