Experimental observation of non-reciprocal band-gaps in a space-time modulated beam using a shunted piezoelectric array

TL;DR

This paper experimentally demonstrates non-reciprocal elastic wave band-gaps in a space-time modulated beam using a piezoelectric array with shunt circuits, enabling unidirectional wave propagation within a specific frequency range.

Contribution

It introduces a novel experimental setup for achieving non-reciprocal band-gaps in elastic waves through space-time modulation of a piezoelectric array on a beam.

Findings

Achieved 1 kHz-wide directional band-gaps from 8 to 11 kHz.

Demonstrated unidirectional wave propagation at bandgap frequencies.

Implemented space-time modulation using shunt circuits and switches.

Abstract

In this work we experimentally achieve 1 kHz-wide directional band-gaps for elastic waves spanning a frequency range from approximately 8 to 11 kHz. One-way propagation is induced by way of a periodic waveguide consisting in an aluminum beam partially covered by a tightly packed array of piezoelectric patches. The latter are connected to shunt circuits and switches which allow for a periodic modulation in time of the cell properties. A traveling stiffness profile is obtained by opportunely phasing the temporal modulation of each active element, mimicking the propagation of a plane wave along the material, therefore establishing unidirectional wave propagation at bandgap frequencies.