Analysis of the interaction of helmholtz resonators in periodic acoustic metamaterials depending on its orientation with the acoustic source.

Acoustic screens based on sonic crystals constitute one of the most promising technological bets of recent years in the field of environmental acoustics. Sonic crystals are defined as new materials formed by arrays of acoustic scatterers embedded in air. The design of these screens is made using powerful simulation models that provide reliable results without the need of expensive experimental testing. This project applies the finite elements method in order to analise an acoustic barrier that includes (Helmholtz) resonators in its scatterers, and studies the interference of the sonic crystal with the effect of the Helmholtz resonator, depending on its orientation with the acoustic source.

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Numerical study for increasement of low frequency sound insulation of double-panel structure using sonic crystals with distributed Helmholtz resonators

International Journal of Modern Physics B ◽

10.1142/s0217979219501388 ◽

2019 ◽

Vol 33 (14) ◽

pp. 1950138

Author(s):

Myong-Jin Kim

Keyword(s):

Free Space ◽

Transmission Loss ◽

Numerical Study ◽

Low Frequency ◽

Helmholtz Resonator ◽

Sound Insulation ◽

The Finite Element Method ◽

Helmholtz Resonators ◽

Sonic Crystal ◽

Sonic Crystals

Numerical simulations of the sound transmission loss (STL) of a double-panel structure (DPS) with sonic crystal (SC) comprised of distributed local resonators are presented. The Local Resonant Sonic Crystal (LRSC) consists of “C”-shaped Helmholtz resonator columns with different resonant frequencies. The finite element method is used to calculate the STL of such a DPS. First, the STLs of LRSC in free space and the DPS with LRSC are calculated and compared. It is shown that the sound insulations of the local resonators inserted in the double panel are higher than that in free space for the same size of the SCs and the same number of columns. Next, STL of the DPS in which the SC composed of three columns of local resonators having the same outer and inner diameters but different slot widths are calculated, and a reasonable arrangement order is determined. Finally, the soundproofing performances of DPS with distributed LRSC are compared with the case of insertion of general cylindrical SC for SC embedded in glass wool and not. The results show that the sound insulation of the DPS can be significantly improved in the low frequency range while reducing the total mass without increasing the thickness.

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ACOUSTIC BAND GAP FORMATION IN TWO-DIMENSIONAL LOCALLY RESONANT SONIC CRYSTALS COMPRISED OF HELMHOLTZ RESONATORS

International Journal of Modern Physics B ◽

10.1142/s0217979209063390 ◽

2009 ◽

Vol 23 (20n21) ◽

pp. 4234-4243 ◽

Cited By ~ 9

Author(s):

L. CHALMERS ◽

D. P. ELFORD ◽

F. V. KUSMARTSEV ◽

G. M. SWALLOWE

Keyword(s):

Band Gap ◽

Experimental Testing ◽

Wide Band ◽

Band Gaps ◽

Gap Formation ◽

Helmholtz Resonators ◽

Multiple Resonance ◽

Resonance Band ◽

Sonic Crystal ◽

Sonic Crystals

We present a new type of sonic crystal technology offering a novel method of achieving broad acoustic band gaps. The proposed design of a locally resonating sonic crystal (LRSC) is constructed from "C"-shaped Helmholtz resonators as opposed to traditional solid scattering units. This unique construction enables a two band gap system to be generated in which the first — a Bragg type band gap, arises due to the periodic nature of the crystal, whilst the second gap results from resonance of the air column within the resonators. The position of this secondary band gap is found to be dependent upon the dimensions of the resonating cavity. The band gap formation is investigated theoretically using finite element methods, and confirmed through experimental testing. It is noted that the resonance band gaps detected cover a much broader frequency range (in the order of kHz) than has been achieved to date. In addition the possibility of overlapping such a wide band gap with the characteristic Bragg gap generated by the structure itself could yield gaps of even greater range. A design of sonic crystal is proposed, that comprises of several resonators with differing cavity sizes. Such a structure generates multiple resonance gaps corresponding to the various resonator sizes, which may be overlapped to form yet larger band gaps. This multiple resonance gap system can occur in two configurations. Firstly a simple mixed array can be created by alternating resonator sizes in the array and secondly using a system coined the Matryoshka (Russian doll) array in which the resonators are distributed inside one another. The proposed designs of LRSC's offer a real potential for acoustic shielding using sonic crystals, as both the size and position of the band gaps generated can be controlled. This is an application which has been suggested and investigated for several years with little progress. Furthermore the frequency region attenuated by resonance is unrelated to the crystals lattice constant, providing yet more flexibility in the design of such devices.

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Analysis of the interaction of Helmholtz resonators in periodic acoustic metamaterials depending on its orientation with the acoustic source

The Journal of the Acoustical Society of America ◽

10.1121/10.0004576 ◽

2021 ◽

Vol 149 (4) ◽

pp. A79-A79

Author(s):

David R. Solana ◽

Sergio Castiñeira-Ibáñez ◽

Javier Redondo ◽

Jose María Bravo-Plana-Sala ◽

Rubén Picó ◽

...

Keyword(s):

Acoustic Metamaterials ◽

Acoustic Source ◽

Helmholtz Resonators

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Acoustical Study of a Lossy Gradient-Based Sonic Crystal Using Acoustic Beamforming

Fluctuation and Noise Letters ◽

10.1142/s0219477522500171 ◽

2021 ◽

Author(s):

Debasish Panda ◽

Amiya Ranjan Mohanty

Keyword(s):

Acoustic Waves ◽

Periodic Structures ◽

Fast Method ◽

Fe Method ◽

Helmholtz Resonators ◽

Sonic Crystal ◽

Gradient Based ◽

Acoustical Study ◽

Tunable Frequency ◽

Sonic Crystals

Sonic crystals (SCs) are unique periodic structures designed to attenuate acoustic waves in tunable frequency bands known as bandgaps. Though previous works on conventional uniform SCs show good insertion loss (IL) inside the bandgaps, this work is focused on widening their bandgaps and achieving better IL inside the bandgaps by using a gradient-based sonic crystal (GBSC). The GBSC applies property gradient to the conventional SC array by varying its basic properties, i.e., the distance between the scatterers/resonators (lattice constant), and resonator dimensions between the columns and hence the name GBSC. The design of the GBSC is backed by the results of acoustic beamforming experiments conducted over the uniform SCs of hollow scatterers and Helmholtz resonators (HRs) having two-dimensional (2D) periodicity prepared by using Polyvinyl chloride (PVC) pipes without any property gradient and their respective 2D finite element (FE) studies. The experimental and FE simulation results of the uniform SCs were found to be in good agreement and therefore, the GBSC was modeled and analyzed using FE method considering the viscothermal losses inside the resonators. The results indicated that the property gradient improves both Bragg scattering and Helmholtz resonance compared to that of the uniform SCs and therefore, the GBSC exhibits wider attenuation gaps and higher attenuation levels. An array of 30 microphones was used to conduct acoustic beamforming experiments on the uniform SCs. Beamforming was found to be an advanced and fast method to perform quick measurements on the SCs.

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Design of Acoustic Metamaterials for Super-Resolution Ultrasound Imaging

Volume 10: Mechanics of Solids and Structures, Parts A and B ◽

10.1115/imece2007-44076 ◽

2007 ◽

Author(s):

Shu Zhang ◽

Leilei Yin ◽

Nicholas Fang

Keyword(s):

Ultrasound Imaging ◽

Super Resolution ◽

Helmholtz Resonator ◽

Effective Density ◽

Acoustic Metamaterials ◽

Sound Sources ◽

Acoustic Metamaterial ◽

Helmholtz Resonators ◽

Planar Network ◽

Weight Design

We report the numerical design and preliminary experiment of 2-D acoustic metamaterials composed of a planar network of subwavelength Helmholtz resonators. The considerably smaller size of the Helmholtz resonator to the corresponding resonant wavelength, allows a compact and light weight design for kilohertz frequency applications. Based on transmission line model to describe the acoustic wave propagation inside such ultrasonic metamaterials, we derived the acoustic parameters such as effective density and compressibility. Extremely large or even negative value of effective density and compressibility can be designed in this acoustic metamaterial. Our simulation demonstrates the focusing and imaging of sound sources through different lenses made of this novel acoustic metamaterial, which may have great potential application in ultrasound imaging. The influences of frequency and source position on the property of the focused image are also investigated.

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Effect of Incident Acoustic Pressure Amplitude on the Transmission Loss of Helmholtz Resonators

Vibration ◽

10.3390/vibration3010004 ◽

2020 ◽

Vol 3 (1) ◽

pp. 34-41

Author(s):

Karim Sachedina ◽

Thomas Lato ◽

Atef Mohany ◽

Marwan Hassan

Keyword(s):

Acoustic Pressure ◽

Transmission Loss ◽

Experimental Studies ◽

Helmholtz Resonator ◽

Test Element ◽

Pressure Amplitude ◽

Acoustic Source ◽

Expansion Chamber ◽

Source Power ◽

Helmholtz Resonators

Acoustic transmission loss is a common parameter utilized throughout several studies to evaluate the acoustic characteristics of a given test element. Transmission loss has been frequently referred to as a source independent parameter. However, this work presents evidence that the incident acoustic pressure amplitude does, in fact, have an effect on the measured transmission loss for some passive damping devices. The transmission loss was experimentally measured utilizing the two-source location method and the specimens tested include an expansion chamber, a quarter wave resonator, a Herschel–Quincke tube and various Helmholtz resonators. When varying the power supplied to the acoustic source, it was noted that all the devices exhibited nearly constant values of transmission loss, with the exception of the Helmholtz resonators. The Helmholtz resonators had a significant variance of transmission loss with respect to the acoustic source power. This decrease in performance is caused by the “jet-flow” phenomenon occurring at the Helmholtz resonator neck, which results in increased acoustic losses. The present work illustrates that the assumption of source independence, which is often made when using transmission loss to evaluate damping devices, must be taken with caution, as this assumption is case dependent and may be crucial when scaling experimental studies to an industrial setting.

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Design, Manufacturing, and Acoustical Analysis of a Helmholtz Resonator-Based Metamaterial Plate

Acoustics ◽

10.3390/acoustics3040040 ◽

2021 ◽

Vol 3 (4) ◽

pp. 630-641

Author(s):

Sourabh Dogra ◽

Arpan Gupta

Keyword(s):

Transmission Loss ◽

Sound Transmission ◽

Helmholtz Resonator ◽

Acoustic Properties ◽

Sound Transmission Loss ◽

Sound Waves ◽

Acoustic Metamaterials ◽

Additional Advantage ◽

Helmholtz Resonators ◽

High Sound

Acoustic metamaterials are materials artificially engineered to control sound waves, which is not possible with conventional materials. We have proposed a design of an acoustic metamaterial plate with inbuilt Helmholtz resonators. The plate is made of Polylactic acid (PLA) which is fabricated using an additive manufacturing technique. It consists of Helmholtz resonator-shaped cavities of different sizes. In this paper, we have analyzed the acoustic properties of the Helmholtz resonators-based metamaterial plate experimentally as well as numerically. The experimental results are in good agreement with the numerical results. These types of 3D-printed metamaterial plates can find their application where high sound transmission loss is required to create a quieter ambience. There is an additional advantage of being lightweight because of the Helmholtz resonator-shaped cavities built inside the plate. Thus, these types of metamaterial plates can find their application in the design sector requiring lighter materials with high sound transmission loss.

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