Bridging coupling bandgaps in nonlinear acoustic metamaterials

TL;DR

This paper introduces a mechanism for coupling bandgaps in nonlinear acoustic metamaterials, enabling control over chaotic bands and wave suppression through nonlinear resonator interactions, supported by theoretical and experimental analysis.

Contribution

It presents a novel bridging coupling mechanism for bandgaps in NAMs, expanding the understanding and control of nonlinear wave suppression effects.

Findings

Bridging coupling generates chaotic bands in NAMs.

Bandwidth and wave reduction efficiency are tunable via frequency modulation.

Experimental results confirm the theoretical triatomic model analysis.

Abstract

Nonlinear acoustic metamaterials (NAMs) open new freedoms in exploiting novel technologies for wave manipulations. Recently, the desired ultra-low and ultra-broad-band wave suppressions were achieved by the chaotic bands in NAMs [Nature Commun. 8, 1288 (2017)]. This work describes a remote interaction mechanism in NAMs-bridging coupling of nonlinear locally resonant bandgaps. Bridging bandgaps generate chaotic bands and share the negative mass between nonlinear resonators. The bandwidth and the efficiency for the wave reduction in chaotic bands can be manipulated effectively by modulating the frequency distance between the bridging pair. Theoretical analyses on the triatomic model containing two nonlinearly coupled resonances clarify the principle of bridging bandgaps. NAM beams are created to demonstrate this mechanism experimentally by including the bifurcations of periodic solutions. Our study extends the content of NAMs and more nonlinear effects are anticipated based on this mechanism.