Double-negative acoustic metamaterial based on hollow steel tube meta-atom

TL;DR

This paper introduces a novel double-negative acoustic metamaterial using hollow steel tubes and split hollow spheres, demonstrating negative effective mass and modulus, and capable of sub-wavelength acoustic imaging at 1630Hz.

Contribution

It presents a new design of 2D and 3D acoustic metamaterials with double-negative properties based on hollow steel tubes and split hollow spheres, with experimental validation.

Findings

Demonstrated negative effective mass density and modulus in the metamaterials.

Achieved sub-wavelength acoustic imaging at 1630Hz.

Validated the double-negative behavior through experiments.

Abstract

We presented an acoustic 'meta-atom' model of hollow steel tube (HST). The simulated and experimental results demonstrated that the resonant frequency is closely related to the length of the HST. Based on the HST model, we fabricated a two-dimensional (2D) acoustic metamaterial (AM) with negative effective mass density, which put up the transmission dip and accompanied inverse phase in experiment. By coupling the HST with split hollow sphere (SHS), another kind of 'meta-atom' with negative effective modulus in the layered sponge matrix, a three-dimensional (3D) AM was fabricated with simultaneously negative modulus and negative mass density. From the experiment, it is shown that the transmission peak similar to the electromagnetic metamaterials exhibited in the double-negative region of the AM. We also demonstrated that this kind of doble-negative AM can faithfully distinguish the acoustic sub-wavelength details ({\lambda}/7) at the resonance frequency of 1630Hz.