Experimental Observation of Reversed Doppler Effects in Acoustic Metamaterials

TL;DR

This study experimentally demonstrates broadband reversed Doppler effects in an acoustic metamaterial with negative elastic modulus and mass density, verified through simulations and experiments, highlighting a new design approach for broad-frequency negative refraction.

Contribution

It introduces a novel acoustic metamaterial with double-meta-molecule clusters that achieves broadband reversed Doppler effects and negative refraction.

Findings

Broadband reversed Doppler effects observed experimentally.

Metamaterial exhibits negative refraction over a broad frequency range.

Frequency shift increases continuously with frequency.

Abstract

This paper reports an experimental observation of broadband reversed Doppler effects using an acoustic metamaterial with seven flute-like double-meta-molecule clusters. Simulations and experiments verify that this locally resonant acoustic metamaterial with simultaneous negative elastic modulus and mass density can realize negative refraction in a broad frequency range. The constructed metamaterial exhibits broadband reversed Doppler effects. The frequency shift increases continuously as the frequency increases. The assembling of double-meta-molecule clusters introduces a new direction in designing double-negative acoustic metamaterials in an arbitrarily broad frequency range and other various applications.