Simulation of Fabry-Perot Resonance for 3D Printable Complex Holey Acoustic Metamaterials

2020 ◽  
Author(s):  
Sanjay Ravichandran ◽  
Xin Wu ◽  
Yutai Su ◽  
Jing Shi
Keyword(s):  
Resonance Condition ◽  
Simulation Method ◽  
Complex Structures ◽  
Sound Waves ◽  
Acoustic Metamaterials ◽  
Frequency Range ◽  
Acoustic Metamaterial ◽  
Fabry Perot ◽  
Audible Frequency ◽  
Sub Wavelength

Abstract An acoustic metamaterial is a kind of material that is artificially designed in such a way that it can manipulate, control and direct sound waves. To date, various designs for acoustic metamaterials in the imaging applications have been proposed. However, these designs are generally simple due to the restriction from conventional manufacturing methods. By taking advantage of the additive manufacturing (AM) techniques, many complex acoustic metamaterials could be realized. However, the research on the complex structures for imaging applications has been very limited. In this paper, various 3D printable holey structured metamaterials with only one aperture are proposed, and the application possibility for sub-wavelength acoustic imaging in the audible frequency range is investigated. By using numerical simulation method, the effect of transmission properties of incident evanescent waves is analyzed to see whether these waves can completely transmit through the metamaterial. The phenomenon of Fabry-Perot resonances (FPR) that occur inside the hole for five different aperture shapes which are air-filled is studied, and the possibility of operating in a broadband resonance condition for the five designs are analyzed. These results can also be used to obtain valuable information for realizing a broadband acoustic hyperlens, which is an emerging application of 3D printable acoustic metamaterials.

Concealed Weapon Detection Using Acoustic Spectral Characterisation

2009 ◽  
Author(s):  
George A. Vadakkel ◽  
S. Olutunde Oyadiji
Keyword(s):  
Acoustic Signal ◽  
Acoustic Waves ◽  
Natural Frequencies ◽  
Sound Waves ◽  
Frequency Range ◽  
Ultrasonic Sound ◽  
Audible Frequency ◽  
Spectral Characterisation ◽  
Concealed Weapon Detection ◽  
Experimental Trials

This paper focuses on showing how one could identify a component by using acoustic waves within the audible frequency range. The purpose of this study is to incorporate the findings from this paper in concealed weapon detection (CWD) where objects hidden behind a person’s clothing could be detected using acoustic or ultrasonic sound waves. Experimental trials are carried out using a directional speaker which generates a highly directional acoustic beam. This can then be pointed at any target and the sound reflected from it analyzed. Initially, a sound source is selected based on the maximum frequency range. The characteristic of the acoustic signal produced by the source is then recorded to be used as reference. Different objects are selected to be used as targets. The sound reflected from these objects is recorded. The spectrograms from these targets reveal that the incident sound waves have been modulated. By taking the ratio of the reflected and the incident sound signals one could obtain the natural frequencies of the object and the spectrogram of the reflected acoustic signal could give indication of the object’s shape.

scholarly journals The Effect of Geometrical Parameters on Resonance Characteristics of Acoustic Metamaterials with Negative Effective Modulus

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Xiao-Le Yan ◽  
Li-Mei Hao ◽  
Mei-Ling Men ◽  
Zhi Chen
Keyword(s):  
Resonance Frequency ◽  
Analytical Formula ◽  
Blue Shift ◽  
Theory Model ◽  
Outer Radius ◽  
Effective Modulus ◽  
Geometrical Parameters ◽  
Sound Waves ◽  
Acoustic Metamaterials ◽  
Acoustic Metamaterial

There has been an explosion of interest in acoustic metamaterial in the last ten years. The tunable negative acoustic metamaterial is an important issue for designing metamaterials. The acoustic metamaterial is restricted by the narrow bandgap of sound waves for the local resonance of metamaterial unit cells. By shifting the sizes of the unit cell, the acoustic metamaterial could potentially overcome the limit of the narrow resonance frequency. In this research, we focus on the resonant behavior of split hollow sphere (SHS) in the waveguide. Firstly, we analyze the resonance characteristics of SHS and get an analytical formula for the effect of geometrical parameters on the resonance frequency. Furthermore, the resonance frequency of SHS is verified with finite-element method analysis based on COMSOL Multiphysics simulation. The results are in good agreement with theory model. It is observed that there is a blue shift of the resonance frequency with the gradual increase of the neck radius of SHS, a V-type response curve with the increase of inner radius of SHS, and a red shift with the increase of outer radius of SHS. Using the method of estimate of resonance, we could get a precisely controllable unit structure with negative effective modulus and offer a way to optimize the realization of double negative acoustic metamaterial.

A membrane-type acoustic metamaterial muffler

2017 ◽  
Vol 31 (08) ◽  
pp. 1750049 ◽  
Author(s):  
Fang Wang ◽  
Tianning Chen ◽  
Xiaopeng Wang ◽  
Kai Bao ◽  
Lele Wan
Keyword(s):  
Transmission Loss ◽  
Low Frequency ◽  
Acoustic Metamaterials ◽  
Acoustic Transmission ◽  
Frequency Range ◽  
Transmission Performance ◽  
Acoustic Metamaterial ◽  
Dynamic Mass ◽  
Membrane Type ◽  
Theoretical Results

Membrane-type acoustic metamaterials (MAMs) with negative dynamic mass have demonstrated the effects in the sound transmission loss (STL) at low-frequency range. This research aims to design a membrane-type acoustic metamaterial muffler (MAMM) based on the present MAMs, and to solve the problem that airflow cannot flow unimpededly in the channel once using the MAMs. For a better understanding of MAMM, the resonance frequency of the membrane was calculated and simulation was used to study the acoustic transmission performance of the MAMM. The simulation results were verified in comparison with the theoretical results of the membrane. This MAMM reduced the structural size of muffler compared with the traditional Helmholtz muffler and expand muffler, which can find application for the MAMs in acoustic absorption and noise control.

scholarly journals Theoretical Optimization of Trapped-Bubble-Based Acoustic Metamaterial Performance

2020 ◽  
Vol 10 (16) ◽  
pp. 5720
Author(s):  
Dmitry Gritsenko ◽  
Roberto Paoli
Keyword(s):  
Low Frequency ◽  
Impedance Change ◽  
Sound Waves ◽  
Acoustic Metamaterials ◽  
Resonant Frequencies ◽  
Acoustic Metamaterial ◽  
Precise Control ◽  
Resonant Behavior ◽  
Versatile Tool ◽  
Analytical Expressions

Acoustic metamaterials have proven to be a versatile tool for the precise control and manipulation of sound waves. One of the promising designs of acoustic metamaterials employ the arrays of bubbles and find applications for soundproofing, blast mitigation, and many others. An obvious advantage of bubble-based metamaterials is their ability to be relatively thin while absorbing low-frequency sound waves. The vast majority of theories developed to predict resonant behavior of bubble-based metamaterials capitalize on Minnaert frequency. Here, we propose a novel theoretical approach to characterize bubble-based metamaterials that are based on our previous findings for a single bubble trapped in circular cavity modeled as a thin clamped plate. We obtain analytical expressions for resonant frequencies of bubble metascreens using self-consistent approximation. Two geometry factors, distance between bubble centers and distance between bubble center and interface of acoustic impedance change, are taken into account. We demonstrate the existence of multiple bandgaps and possibility of switching between them via adjustment of geometry parameters and reflector properties.

2d And 3d Acoustic Metamaterials Using Space Coil Design

2015 ◽  
Vol 1753 ◽  
Author(s):  
Santosh K. Maurya ◽  
Manu Sahay ◽  
Shobha Shukla ◽  
Sumit Saxena
Keyword(s):  
Acoustic Wave ◽  
Mass Density ◽  
3D Structure ◽  
Three Dimensional ◽  
Acoustic Metamaterials ◽  
Coil Design ◽  
Frequency Range ◽  
2D And 3D ◽  
Constitutive Parameters ◽  
Sub Wavelength

ABSTRACTVarious promising applications such as acoustic cloaking, sub-wavelength imaging, acoustic wave manipulation, transmission or reflection control etc. are feasible because of the ability of manipulating sounds and vibrations using artificially engineered “Acoustics meta-materials”. Recent works on space-coiling acoustic metamaterials show their extreme constitutive parameters like large refractive index, double negativity and zero mass density. Three dimensional structures have a wide application in sub-wavelength broadband acoustic wave suppression due to huge attenuation. Here we report the study of propagated and transmitted wave through 3D acoustic metamaterials structure using finite element method. Our simulations on 3D structure show a huge absorption/damping over few hundreds kilohertz frequency range.

SIMULATION OF THE TRANSFER FUNCTION FOR A HEAD-AND-TORSO MODEL OVER THE ENTIRE AUDIBLE FREQUENCY RANGE

2007 ◽  
Vol 15 (04) ◽  
pp. 429-448 ◽  
Author(s):  
TOMI HUTTUNEN ◽  
EIRA T. SEPPÄLÄ ◽  
OLE KIRKEBY ◽  
ASTA KÄRKKÄINEN ◽  
LEO KÄRKKÄINEN
Keyword(s):  
Finite Element ◽  
Transfer Function ◽  
Spherical Geometry ◽  
Simulation Method ◽  
Frequency Range ◽  
Torso Model ◽  
Audible Frequency ◽  
Element Type ◽  
Plane Wave Basis Functions ◽  
Wave Problems

In this study, a method for simulating the transfer function of a head-and-torso model over the entire audible frequency range is introduced. The simulation method uses the ultra-weak variational formulation (UWVF) which is a finite element type method tailored for wave problems. In particular, the UWVF uses plane wave basis functions which better approximate the oscillatory field than a polynomial basis used in the standard finite element methods (FEM). This leads to reduction in the computational complexity at the high frequencies which, accompanied with parallel computing, extends the feasible frequency range of the UWVF method. The accuracy of the new simulation tool is investigated using a simple spherical geometry after which the method used for preliminary HRTF simulations in the geometry of a widely used head-and-torso mannequin.

Transmission control of acoustic metasurface with dumbbell-shaped double-split hollow sphere

2020 ◽  
Vol 34 (33) ◽  
pp. 2050386
Author(s):  
Yibao Dong ◽  
Yuanbo Wang ◽  
Jianxiang Sun ◽  
Changlin Ding ◽  
Shilong Zhai ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Simple Structure ◽  
Negative Refraction ◽  
Hollow Spheres ◽  
Complex Structures ◽  
Sound Waves ◽  
Large Size ◽  
Audible Frequency ◽  
Potential Applications ◽  
Focusing Lens

Complex structures, large size and limited manipulation of acoustic waves are the problems that restrict the development of acoustic metasurfaces. Here, we report a transmission-type acoustic metasurface based on local resonance mechanism, which is composed of meta-atomic units called dumbbell-shaped double-split hollow spheres (DSDSHS). This metasurface with subwavelength scale has the advantage of simple structure and easy preparation, and can realize the full manipulation of sound waves. Negative refraction with different transmission angles and high intensity plate focusing lens are realized in the air environment of audible frequency. The proposed metasurface has potential applications in the miniaturization and integration of sound transmission and sound energy collection, opening a new opportunity for manipulation of acoustic wavefront.

scholarly journals Bilayer ventilated labyrinthine metasurfaces with high sound absorption and tunable bandwidth

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiayuan Du ◽  
Yuezhou Luo ◽  
Xinyu Zhao ◽  
Xiaodong Sun ◽  
Yanan Song ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Air Flow ◽  
Single Layer ◽  
Sound Waves ◽  
Acoustic Metamaterials ◽  
Sound Barrier ◽  
Free Air ◽  
Relative Bandwidth ◽  
Wide Range ◽  
High Sound

AbstractThe recent advent of acoustic metamaterials offers unprecedented opportunities for sound controlling in various occasions, whereas it remains a challenge to attain broadband high sound absorption and free air flow simultaneously. Here, we demonstrated, both theoretically and experimentally, that this problem can be overcome by using a bilayer ventilated labyrinthine metasurface. By altering the spacing between two constituent single-layer metasurfaces and adopting asymmetric losses in them, near-perfect (98.6%) absorption is achieved at resonant frequency for sound waves incident from the front. The relative bandwidth of absorption peak can be tuned in a wide range (from 12% to 80%) by adjusting the open area ratio of the structure. For sound waves from the back, the bilayer metasurface still serves as a sound barrier with low transmission. Our results present a strategy to realize high sound absorption and free air flow simultaneously, and could find applications in building acoustics and noise remediation.

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