Experimental Observation of Nonreciprocal Band Gaps in a Space-Time-Modulated Beam Using a Shunted Piezoelectric Array

Abstract

The breaking of reciprocity in elastic wave propagation can be achieved through modulation of stiffness in space and time, which is reflected in asymmetrical Bloch diagrams. Here this principle is experimentally demonstrated using controlled piezoelectric devices, which when connected to negative-capacitance circuits alter the effective material parameters locally, in the form of a traveling modulation. Thus the authors can tune nonreciprocal band gaps that are1 kHz wide and span a frequency range of 8--11 kHz, for one-way transmission of vibrations in $e.g.$ phononic communication systems.