Lightweight stiffness-dominated acoustic metamaterial barrier for low-frequency sound

Abstract

In this study, we experimentally demonstrate a class of lightweight acoustic metamaterial barriers that block low-frequency sound. The acoustic metamaterial barrier is composed of a thin rubber membrane coated over a stiff honeycomb plate. Our findings, combined with high-fidelity finite element simulations, demonstrate that the sound insulation performance of the acoustic metamaterial surpasses the mass law in three distinct frequency ranges: (a) the stiffness law dominates insulation up to 140 Hz, (b) degeneracy and destructive superposition of high-order natural modes dominate within the frequency range of 300–500 Hz, and (c) destructive interference between high-order resonance and membrane resonance dominates in the frequency range of 800–1200 Hz. Notably, our study highlights the potential of high-order shear vibration of the periodic structure for the resonant bending waves of the honeycomb cell that coincide with the wavelengths of longitudinal sound waves in air, thereby offering new design guidelines for lightweight acoustic metamaterial barriers. This study reports for the first time the coincidence of high-order and membrane resonance modes within the honeycomb cell by employing an accurate finite element model and experimental validation.

Ultra-ventilated sound absorption metamaterial lamina

“…The emergence of acoustic metamaterials, which refers to artificial structural materials with unconventional acoustic properties, provides a new solution to the problem of low-frequency noise reduction. After a fast development over the last 20 years, acoustic metamaterials have made significant progress in various areas and become necessary building blocks for acoustic focusing [7][8][9], imaging [10,11], vibration and noise reduction [12][13][14][15][16][17], and a variety of topological phenomena [18][19][20][21]. Acoustic metamaterials for vibration and noise reduction are divided into sound-insulating metamaterials [22][23][24] and sound-absorbing metamaterials.…”