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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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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Parametric Study on Rectangular Sonic Crystal

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.152-154.281 ◽

2012 ◽

Vol 152-154 ◽

pp. 281-286 ◽

Cited By ~ 5

Author(s):

Arpan Gupta ◽

Kian Meng Lim ◽

Chye Heng Chew

Keyword(s):

Band Gap ◽

Periodic Structure ◽

Parametric Study ◽

Sound Propagation ◽

Periodic Structures ◽

Sound Attenuation ◽

Experimental Results ◽

Center Frequency ◽

Sonic Crystal ◽

Sonic Crystals

Sonic crystals are periodic structures made of sound hard scatterers which attenuate sound in a range of frequencies. For an infinite periodic structure, this range of frequencies is known as band gap, and is determined by the geometric arrangement of the scatterers. In this paper, a parametric study on rectangular sonic crystal is presented. It is found that geometric spacing between the scatterers in the direction of sound propagation affects the center frequency of the band gap. Reducing the geometric spacing between the scatterers in the direction perpendicular to the sound propagation helps in better sound attenuation. Such rectangular arrangement of scatterers gives better sound attenuation than the regular square arrangement of scatterers. The model for parametric study is also supported by some experimental results.

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Band Structure in a Sustainable Sonic Crystal

Materials Science Forum ◽

10.4028/www.scientific.net/msf.958.75 ◽

2019 ◽

Vol 958 ◽

pp. 75-80

Author(s):

Edson Jansen Pedrosa Miranda Jr. ◽

S.F. Rodrigues ◽

J.M.C. dos Santos

Keyword(s):

Band Structure ◽

Cross Section ◽

Cross Sections ◽

Acoustic Waves ◽

Band Gaps ◽

Square Lattice ◽

Host Medium ◽

Fiber Cross Section ◽

Sonic Crystal ◽

Sonic Crystals

During the last few decades many researchers have been interested in acoustic wave propagation in artificial periodic composites known as sonic crystals. Sonic crystals have received renewed attention because they exhibit acoustic band gaps where there are only evanescent waves. Sonic crystals consist of a periodic array of scatterers embedded in a host medium. The host medium and/or scatterers are fluids. We investigate the band structure of acoustic waves propagating in a sustainable sonic crystal composed by miriti fibers and air, regarding square and triangular lattices. Miriti fibers are extracted from buriti palm petiole (Mauritia flexuosa Mart.), which is a typical specie that grows in Amazonian region. We also study the influence of miriti fiber cross section, i.e. circular, hollow circular, square and rotated square with a 45° angle of rotation with respect to x, y axes. Plane wave expansion method is used to solve the wave equation. Acoustic band gaps are observed for all miriti fiber cross sections and lattices. The best performances of the sustainable sonic crystal are for triangular lattice, regarding circular and rotated square miriti fiber cross sections, and for square lattice with circular miriti fiber cross section. We suggest that the sustainable sonic crystal should be feasible for noise management.

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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.

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-1369 ◽

2021 ◽

Vol 263 (6) ◽

pp. 215-226

Author(s):

David Ramírez ◽

Sergio Castiñeira-Ibáñez ◽

Jose Maria Bravo-Plana-Sala ◽

Juan Vicente Sánchez-Pérez ◽

Rubén Picó

Keyword(s):

Experimental Testing ◽

Helmholtz Resonator ◽

Simulation Models ◽

Acoustic Metamaterials ◽

New Materials ◽

Acoustic Source ◽

Helmholtz Resonators ◽

Sonic Crystal ◽

Environmental Acoustics ◽

Sonic Crystals

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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