Sound Manipulation With Acoustic Metamaterials

2012 ◽  
Author(s):  
Lucian Zigoneanu ◽  
Bogdan-Ioan Popa ◽  
Steven A. Cummer
Keyword(s):  
Effective Density ◽  
Gradient Index ◽  
Acoustic Metamaterials ◽  
Acoustic Wave Propagation ◽  
Material Parameters ◽  
Unit Cells ◽  
Novel Applications ◽  
Practical Feasibility ◽  
Transformation Acoustics ◽  
Sub Wavelength

Acoustic metamaterials are engineered materials with properties hard or impossible to find in natural materials (e.g. negative effective density and/or negative bulk modulus). Therefore, a myriad of novel applications could be imagined and some of them have already been theoretically and/or experimentally demonstrated. Gradient index acoustic lenses, acoustic cloaks or acoustic absorbing panels are some common examples. Here, we review the coordinate transformation approach (transformation acoustics) which provides the material parameters needed to precisely control the acoustic wave propagation. Then, we use this technique to design an acoustic black hole and a 3D acoustic ground cloak. We use numerical simulations to explore the practical feasibility of the material parameters required by these applications and design non-resonant, highly sub-wavelength unit cells that will implement them in practice.

scholarly journals Two-Dimensional Composite Acoustic Metamaterials of Rectangular Unit Cell from Pentamode to Band Gap

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1457
Author(s):  
Qi Li ◽  
Ke Wu ◽  
Mingquan Zhang
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Band Gap ◽  
Unit Cell ◽  
The Other ◽  
Two Dimensional ◽  
Acoustic Metamaterials ◽  
Acoustic Wave Propagation ◽  
Theoretical Support ◽  
Unit Cells

Pentamode metamaterials have been receiving an increasing amount of interest due to their water-like properties. In this paper, a two-dimensional composite pentamode metamaterial of rectangular unit cell is proposed. The unit cells can be classified into two groups, one with uniform arms and the other with non-uniform arms. Phononic band structures of the unit cells were calculated to derive their properties. The unit cells can be pentamode metamaterials that permit acoustic wave travelling or have a total band gap that impedes acoustic wave propagation by varying the structures. The influences of geometric parameters and materials of the composed elements on the effective velocities and anisotropy were analyzed. The metamaterials can be used for acoustic wave control under water. Simulations of materials with different unit cells were conducted to verify the calculated properties of the unit cells. The research provides theoretical support for applications of the pentamode metamaterials.

Acoustic Metamaterial With Air-Backed Diaphragm for Broadband Absorption: A Preliminary Study

2020 ◽  
Author(s):  
Qian Dong ◽  
Xiaolei Song ◽  
Subhrodeep Ray ◽  
Haijun Liu
Keyword(s):  
Impedance Match ◽  
Center Frequency ◽  
Acoustic Metamaterials ◽  
Perforated Plates ◽  
Broadband Absorption ◽  
Unit Cells ◽  
Equivalent Mass ◽  
3D Printed ◽  
Mass Spring ◽  
Sub Wavelength

Abstract Membrane-based acoustic metamaterials have been reported to achieve 100% absorption, the acoustic analogue of photonic black-hole. However, the bandwidth is usually very narrow around some local resonance frequency, which limits its practical use. To address this limitation and achieve a broadband absorption, this paper first establishes a theoretical framework for unit cells of air-backed diaphragms, modeled as an equivalent mass-spring-dashpot system. Based on the impedance match principle, three different approaches are numerically investigated by tuning the cavity length, the static pressure in the cavity, and the effective damping of perforated plates. A prototype with polyimide diaphragm and 3D printed substrate is then fabricated and characterized using an acoustic impedance tube. Preliminary experiments show the feasibility to achieve an absorption bandwidth of ∼200 Hz at center frequency of 1.45 kHz. This work pays the way for developing a sub-wavelength light weight broadband acoustic absorber for a variety of applications in noise control.

Acoustic Metamaterial Design Method Based on Green Coordinate Transformation

2020 ◽  
Vol 976 ◽  
pp. 15-24
Author(s):  
Xin Xie ◽  
Xiao Ming Wang ◽  
Yu Lin Mei
Keyword(s):  
Coordinate Transformation ◽  
Design Method ◽  
Three Dimensional ◽  
Transformation Method ◽  
Propagation Path ◽  
Acoustic Metamaterials ◽  
Acoustic Wave Propagation ◽  
Acoustic Metamaterial ◽  
Coordinate Transformation Method ◽  
Transformation Acoustics

Acoustic metamaterials have great application prospects in eliminating vibration and noise, but they are difficult to manufacture due to their anisotropy. This paper utilizes the Green coordinate transformation method to design acoustic metamaterials by combining with the transformation acoustics theory. Because the Green coordinate transformation is the pseudo-conformal mapping in three-dimensional coordinates, the anisotropy of designed metamaterials can be weakened. And also, the genetic algorithm is employed to optimize the anisotropy of metamaterials and reduce the designed metamaterial parameter difference further. Finally, the membrane-imbedded-type metamaterial is applied to realize the design and to illustrate the effectiveness of the proposed method by manipulating the acoustic wave propagation path.

scholarly journals MEMS mirrors using sub-wavelength High- Contrast-Gratings with asymmetric unit cells

2016 ◽  
Vol 19 (2) ◽  
pp. 52
Author(s):  
Milan Maksimović
Keyword(s):  
Spectral Response ◽  
Practical Interest ◽  
Optimization Procedure ◽  
Material Design ◽  
Unit Cell ◽  
High Contrast ◽  
Asymmetric Unit ◽  
Unit Cells ◽  
Thin Elements ◽  
Sub Wavelength

High-contrast gratings (HCG) are ultra-thin elements operating in sub-wavelength regime with the period of the grating smaller than the wavelength and with the high-index grating material fully surrounded by low-index material. Design of MEMS mirrors made from HCG with specific reflectivity response is of great practical interest in integrated optoelectronics. We theoretically investigate design of the spectral response for HCGs with the complex unit cells. We show that the spectral response can be tailored via the unit cell perturbations and with the asymmetric unit cell perturbations may introduce completely new spectral response. Our results can serve as guidance for the design of the complex HCGs and help with the choice of the efficient initial grating topology prior to global optimization procedure.

Adjustable sound insulation frequency band through the combination of membrane-type acoustic metamaterial array

2021 ◽  
Vol 263 (1) ◽  
pp. 5869-5877
Author(s):  
Xiang Wu ◽  
TengLong Jiang ◽  
JianWang Shao ◽  
GuoMing Deng ◽  
Chang Jin
Keyword(s):  
Thin Films ◽  
Frequency Band ◽  
Transmission Loss ◽  
Structural Parameters ◽  
Sound Insulation ◽  
Acoustic Metamaterials ◽  
Additional Mass ◽  
Acoustic Metamaterial ◽  
Material Parameters ◽  
Membrane Type

Membrane-type acoustic metamaterials are thin films or plates composed of periodic units with small additional mass. A large number of studies have shown that these metamaterials exhibit tunable anti-resonance, and their transmission loss values are much higher than the corresponding quality laws. At present, most researches on membrane-type acoustic metamaterials focus on the unit cell, and the sound insulation frequency band can only be adjusted by adjusting the structural parameters and material parameters. In this paper, two kinds of acoustic metamaterials with different structures are designed, which are the center placement of the mass and the eccentric placement of the mass.The two structures have different sound insulation characteristics. By designing different array combinations of acoustic metamaterials, the sound insulation peaks of different frequency bands are obtained. This paper studies the corresponding combination law, and effectively realizes the adjustable sound insulation frequency band.

scholarly journals Compact Acoustic Rainbow Trapping in a Bioinspired Spiral Array of Graded Locally Resonant Metamaterials

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 788 ◽  
Author(s):  
Liuxian Zhao ◽  
Shengxi Zhou
Keyword(s):  
Health Monitoring ◽  
Microelectromechanical Systems ◽  
Acoustic Wave Propagation ◽  
Spiral Tube ◽  
Helmholtz Resonators ◽  
Frequency Selection ◽  
Mechanical Waves ◽  
Space Saving ◽  
Spiral Array ◽  
Sub Wavelength

Acoustic rainbow trappers, based on frequency selective structures with graded geometries and/or properties, can filter mechanical waves spectrally and spatially to reduce noise and interference in receivers. These structures are especially useful as passive, always-on sensors in applications such as structural health monitoring. For devices that face space and weight constraints, such as microelectromechanical systems (MEMS) transducers and artificial cochleae, the rainbow trapping structures must be compact as well. To address this requirement, we investigated the frequency selection properties of a space-saving design consisting of Helmholtz resonators arranged at sub-wavelength intervals along a cochlear-inspired spiral tube. The height of the Helmholtz resonators was varied gradually, which induced bandgap formation at different frequencies along the length of the spiral tube. Numerical simulations and experimental measurements of acoustic wave propagation through the structure showed that frequencies in the range of 1–10 kHz were transmitted to different extents along the spiral tube. These rainbow trapping results were achieved with a footprint that was up to 70 times smaller than the previous structures operating at similar bandwidths, and the channels are 2.5 times of the previous structures operating at similar bandwidths.

Tunable acoustic waveguide based on vibro-acoustic metamaterials with shunted piezoelectric unit cells

2015 ◽  
Vol 24 (10) ◽  
pp. 105018 ◽  
Author(s):  
Byung-Jin Kwon ◽  
Jin-Young Jung ◽  
Dooho Lee ◽  
Kwang-Chun Park ◽  
Il-Kwon Oh
Keyword(s):  
Acoustic Metamaterials ◽  
Acoustic Waveguide ◽  
Unit Cells

scholarly journals Evaluation of uncertainty effects to band gap behavior of circuitry-integrated piezoelectric metamaterial using order-reduced analysis

2018 ◽  
Vol 29 (12) ◽  
pp. 2677-2692 ◽  
Author(s):  
Wangbai Pan ◽  
Guoan Tang ◽  
Jiong Tang
Keyword(s):  
Band Gap ◽  
Parameter Uncertainty ◽  
Good Accuracy ◽  
Integrated System ◽  
Acoustic Metamaterials ◽  
Type Analysis ◽  
Design And Synthesis ◽  
Unit Cells ◽  
Geometry Configuration ◽  
Reduced Modeling

Acoustic metamaterials with unit cells that are integrated with piezoelectric transducer circuitry exhibit interesting band gap behaviors that can be used for wave/vibration manipulation. This research reports the evaluation of uncertainty effects to a typical piezoelectric metamaterial, where uncertainties in geometry/configuration and in circuitry elements are taken into consideration. Monte Carlo–type analysis is performed to assess the band gap features under these uncertainties. In order to facilitate tractable computation in uncertainty analysis, order-reduced modeling of the electro-mechanically integrated system is formulated. The component mode synthesis–based order-reduced modeling increases the computational efficiency significantly while maintaining good accuracy. Results show that the band gap behavior is generally less sensitive to configuration uncertainty but can be greatly affected by circuitry parameter uncertainty. These results can be used to guide the design and synthesis of piezoelectric metamaterials, and the method developed can be applied to the uncertainty quantification of other types of metamaterials.

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