Flute-Model Acoustic Metamaterials with Simultaneously Negative Bulk Modulus and Mass Density

TL;DR

This paper reports the experimental creation of a 3D acoustic metamaterial using perforated hollow steel tubes that exhibits simultaneous negative bulk modulus and mass density, demonstrating unique wave manipulation properties.

Contribution

The study introduces a novel 3D flute-model structure that achieves negative bulk modulus and density, verified through transmission, reflection, and focusing experiments.

Findings

Effective bulk modulus and density are negative.

The metamaterial exhibits negative refractive index.

Focusing experiments confirm metamaterial properties.

Abstract

We experimentally constructed a three-dimensional flute-model "molecular" structure acoustic metamaterial(AM)from a periodic array of perforated hollow steel tubes (PHSTs) and investigated its transmission and reflection behaviors in impedance tube system. The AM exhibited a transmission peak and an inverse phase, thus exhibiting the local resonance of the PHSTs. Based on the homogeneous media theory, the effective bulk modulus and mass density of the AM were calculated to be simultaneously negative; the refractive index was also negative. PHST AM slab focusing experiments showed that the medium with a resonant structure exhibited a distinct metamaterial property.