Low frequency topologically protected wave transport in sinusoidal lightweight acoustic metamaterials

Controlling infrasound signals is crucial to many processes ranging from predicting atmospheric events and seismic activities to sensing nuclear detonations. These waves can be manipulated through phononic crystals and acoustic metamaterials. However, at such ultra-low frequencies, the size (usually on the order of meters) and the mass (usually on the order of many kilograms) of these materials can hinder its potential applications in the infrasonic domain. Here, we utilize tunable lattices of repelling magnets to guide and sort infrasound waves into different channels based on their frequencies. We construct our lattices by confining meta-atoms (free-floating macroscopic disks with embedded magnets) within a magnetic boundary. By changing the confining boundary, we control the meta-atoms’ spacing and therefore the intensity of their coupling potentials and wave propagation characteristics. As a demonstration of principle, we present the first experimental realization of an infrasound phonon demultiplexer (i.e., guiding ultra-low frequency waves into different channels based on their frequencies). The realized platform can be utilized to manipulate ultra-low frequency waves, within a relatively small volume, while utilizing negligible mass. In addition, the self-assembly nature of the meta-atoms can be key in creating re-programmable materials with exceptional nonlinear properties.

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Low frequency sound absorption of adjustable membrane-type acoustic metamaterials

Applied Acoustics ◽

10.1016/j.apacoust.2021.108586 ◽

2022 ◽

Vol 188 ◽

pp. 108586

Author(s):

Tuo Xing ◽

Xiaoling Gai ◽

Junjuan Zhao ◽

Xianhui Li ◽

Zenong Cai ◽

...

Keyword(s):

Sound Absorption ◽

Low Frequency ◽

Acoustic Metamaterials ◽

Frequency Sound ◽

Membrane Type

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Application of Acoustic Metamaterials in Low-frequency Vibration and Noise Reduction

Journal of Mechanical Engineering ◽

10.3901/jme.2016.13.068 ◽

2016 ◽

Vol 52 (13) ◽

pp. 68 ◽

Cited By ~ 12

Author(s):

Jiuhui WU

Keyword(s):

Noise Reduction ◽

Low Frequency ◽

Acoustic Metamaterials ◽

Low Frequency Vibration

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A compact and low-frequency acoustic energy harvester using layered acoustic metamaterials

Smart Materials and Structures ◽

10.1088/1361-665x/aafbf6 ◽

2019 ◽

Vol 28 (2) ◽

pp. 025035 ◽

Cited By ~ 6

Author(s):

Xiaole Wang ◽

Jiajie Xu ◽

Jingjing Ding ◽

Chunyu Zhao ◽

Zhenyu Huang

Keyword(s):

Energy Harvester ◽

Low Frequency ◽

Acoustic Energy ◽

Acoustic Metamaterials

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Fractal Acoustic Metamaterials with Subwavelength and Broadband Sound Insulation

Shock and Vibration ◽

10.1155/2019/1894073 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Yu Liu ◽

Meng Chen ◽

Wenshuai Xu ◽

Tao Yang ◽

Dongliang Pei ◽

...

Keyword(s):

Low Frequency ◽

Sound Insulation ◽

Acoustic Metamaterials ◽

The Finite Element Method ◽

Transmission Losses ◽

Effective Parameters ◽

Retrieval Method ◽

Sound Control ◽

S Parameter ◽

Broadband Sound

We construct new fractal acoustic metamaterials by coiling up space, which can allow subwavelength-scale and broadband sound insulation to be achieved. Using the finite element method and the S-parameter retrieval method, the band structures, the effective parameters, and the transmission losses of these acoustic metamaterials with different fractal orders are researched individually. The results illustrate that it is easy to form low-frequency bandgaps using these materials and thus achieve subwavelength-scale sound control. As the number of fractal orders increase, more bandgaps appear. In particular, in the ΓX direction of the acoustic metamaterial lattice, more of these wide bandgaps appear in different frequency ranges, thus providing broadband sound insulation and showing promise for use in engineering applications.

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Plate-Type Acoustic Metamaterials: Experimental Evaluation of a Modular Large-Scale Design for Low-Frequency Noise Control

Acoustics ◽

10.3390/acoustics1020019 ◽

2019 ◽

Vol 1 (2) ◽

pp. 354-368 ◽

Cited By ~ 2

Author(s):

Linus Ang ◽

Yong Koh ◽

Heow Lee

Keyword(s):

Large Scale ◽

Noise Control ◽

Traffic Noise ◽

Low Frequency ◽

Industrial Applications ◽

Frequency Noise ◽

Acoustic Metamaterials ◽

Scale Design ◽

Stress Uniformity ◽

Plate Type

For industrial applications, the scalability of a finalised design is an important factor to consider. The scaling process of typical membrane-type acoustic metamaterials may pose manufacturing challenges such as stress uniformity of the membrane and spatial consistency of the platelet. These challenges could be addressed by plate-type acoustic metamaterials with an internal tonraum resonator. By adopting the concept of modularity in a large-scale design (or meta-panel), the acoustical performance of different specimen configurations could be scaled and modularly combined. This study justifies the viability of two meta-panel configurations for low-frequency (80–500 Hz) noise control. The meta-panels were shown to be superior to two commercially available noise barriers at 80–500 Hz. This superiority was substantiated when the sound transmission class (STC) and the outdoor-indoor transmission class (OITC) were compared. The meta-panels were also shown to provide an average noise reduction of 22.7–27.4 dB at 80–400 Hz when evaluated in different noise environments—traffic noise, aircraft flyby noise, and construction noise. Consequently, the meta-panel may be further developed and optimised to obtain a design that is lightweight and yet has good acoustical performance at below 500 Hz, which is the frequency content of most problematic noises.

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The Present and Future Role of Acoustic Metamaterials for Architectural and Urban Noise Mitigations

Acoustics ◽

10.3390/acoustics1030035 ◽

2019 ◽

Vol 1 (3) ◽

pp. 590-607 ◽

Cited By ~ 4

Author(s):

Sanjay Kumar ◽

Heow Lee

Keyword(s):

Human Life ◽

Low Frequency ◽

Comfort Level ◽

Frequency Noise ◽

Acoustic Metamaterials ◽

Noise Mitigation ◽

Urban Noise ◽

Continuous Growth ◽

Architectural Acoustics

Owing to a steep rise in urban population, there has been a continuous growth in construction of buildings, public or private transport like cars, motorbikes, trains, and planes at a global level. Hence, urban noise has become a major issue affecting the health and quality of human life. In the current environmental scenario, architectural acoustics has been directed towards controlling and manipulating sound waves at a desired level. Structural engineers and designers are moving towards green technologies, which may help improve the overall comfort level of residents. A variety of conventional sound absorbing materials are being used to reduce noise, but attenuation of low-frequency noise still remains a challenge. Recently, acoustic metamaterials that enable low-frequency sound manipulation, mitigation, and control have been widely used for architectural acoustics and traffic noise mitigation. This review article provides an overview of the role of acoustic metamaterials for architectural acoustics and road noise mitigation applications. The current challenges and prominent future directions in the field are also highlighted.

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Hybrid acoustic metamaterial as super absorber for broadband low-frequency sound

Scientific Reports ◽

10.1038/srep43340 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 58

Author(s):

Yufan Tang ◽

Shuwei Ren ◽

Han Meng ◽

Fengxian Xin ◽

Lixi Huang ◽

...

Keyword(s):

Energy Dissipation ◽

Absorption Coefficient ◽

Sound Absorption ◽

Low Frequency ◽

Functional Materials ◽

Theoretical Method ◽

Acoustic Metamaterials ◽

Mechanical Stiffness ◽

Acoustic Metamaterial ◽

Frequency Sound

Abstract A hybrid acoustic metamaterial is proposed as a new class of sound absorber, which exhibits superior broadband low-frequency sound absorption as well as excellent mechanical stiffness/strength. Based on the honeycomb-corrugation hybrid core (H-C hybrid core), we introduce perforations on both top facesheet and corrugation, forming perforated honeycomb-corrugation hybrid (PHCH) to gain super broadband low-frequency sound absorption. Applying the theory of micro-perforated panel (MPP), we establish a theoretical method to calculate the sound absorption coefficient of this new kind of metamaterial. Perfect sound absorption is found at just a few hundreds hertz with two-octave 0.5 absorption bandwidth. To verify this model, a finite element model is developed to calculate the absorption coefficient and analyze the viscous-thermal energy dissipation. It is found that viscous energy dissipation at perforation regions dominates the total energy consumed. This new kind of acoustic metamaterials show promising engineering applications, which can serve as multiple functional materials with extraordinary low-frequency sound absorption, excellent stiffness/strength and impact energy absorption.

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