scholarly journals Fractal Acoustic Metamaterials with Subwavelength and Broadband Sound Insulation

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.

scholarly journals Labyrinthine Structure with Subwavelength and Broadband Sound Insulation

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Heng Jiang ◽  
Yu Liu ◽  
Wenshuai Xu ◽  
Tao Yang ◽  
Dongliang Pei ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Low Frequency ◽  
Good Control ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Sound Waves ◽  
Effective Parameters ◽  
Retrieval Method ◽  
S Parameter ◽  
Broadband Sound

In this text, the combination of spiral structure and zigzag channels is introduced to design labyrinthine structures, in which sound waves can propagate alternately in the clockwise and counterclockwise directions. Finite element method and S-parameter retrieval method are used to calculate band structures, effective parameters, and transmission properties of the structures. The influences of different structural parameters on their acoustic properties are also studied. These results show labyrinthine structures have multiple bandgaps in the range of 0 Hz–1000 Hz, and the proportion of bandgaps exceeds 33%, which indicates labyrinthine structures have good broadband properties. The normalized frequency of the lowest bandgaps is far smaller than 1, which indicates the structures take good control of sound waves on subwavelength scale. Combining units with different structural parameters can achieve better sound insulation. This research provides a new kind of space-coiling structure for low-frequency and broadband sound waves control, which have excellent application prospects.

Multi-mass synergetic coupling perforated bi-layer plate-type acoustic metamaterials for sound insulation

2020 ◽  
Vol 34 (13) ◽  
pp. 2050136
Author(s):  
Weikang Huang ◽  
Tianning Chen ◽  
Quanyuan Jiang ◽  
Xinpei Song ◽  
Wuzhou Yu ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Perforated Plate ◽  
Low Frequency ◽  
Sound Insulation ◽  
Frequency Noise ◽  
Acoustic Metamaterials ◽  
Practical Engineering ◽  
Broadband Sound ◽  
Insulation Performance ◽  
Plate Type

Thin plate-type acoustic metamaterials have the advantages of lightweight, high rigidity and adjustable parameters, showing great practical application values in sound wave control. In this paper, a type of perforated bi-layer plate-type acoustic metamaterials (PBPAM) is designed for low-frequency noise control. The sound insulation peaks can be increased by combining the perforated plate and synergetic masses, making the sound insulation performance close to the mass law at the resonant frequency. Compared to the results predicted by the mass law, a better performance of sound insulation is achieved based on the PBPAM. The effects of the structural parameters are investigated in this study. Based on the impedance tube experiments, the measured results have a good agreement with the simulated ones. This work can provide a reference for low-frequency and broadband sound insulation based on plate-type acoustic metamaterials in practical engineering.

scholarly journals Study on broadband low-frequency sound insulation of multi-channel resonator acoustic metamaterials

AIP Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 045321
Author(s):  
Chi Xu ◽  
Hui Guo ◽  
Yinghang Chen ◽  
Xiaori Dong ◽  
Hongling Ye ◽  
...  
Keyword(s):  
Low Frequency ◽  
Sound Insulation ◽  
Acoustic Metamaterials ◽  
Frequency Sound

Ventilated metamaterials for broadband sound insulation and tunable transmission at low frequency

2021 ◽  
pp. 101348
Author(s):  
Zhenqian Xiao ◽  
Penglin Gao ◽  
Dongwei Wang ◽  
Xiao He ◽  
Linzhi Wu
Keyword(s):  
Low Frequency ◽  
Sound Insulation ◽  
Broadband Sound

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

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.

scholarly journals Predicting double negativity using transmitted phase in space coiling metamaterials

2018 ◽  
Vol 5 (5) ◽  
pp. 171042 ◽  
Author(s):  
Santosh K. Maurya ◽  
Abhishek Pandey ◽  
Shobha Shukla ◽  
Sumit Saxena
Keyword(s):  
Acoustic Waves ◽  
Negative Refraction ◽  
Acoustic Properties ◽  
Propagation Path ◽  
Elastic Response ◽  
Acoustic Metamaterials ◽  
Effective Response ◽  
Retrieval Method ◽  
S Parameter ◽  
Parameter Retrieval

Metamaterials are engineered materials that offer the flexibility to manipulate the incident waves leading to exotic applications such as cloaking, extraordinary transmission, sub-wavelength imaging and negative refraction. These concepts have largely been explored in the context of electromagnetic waves. Acoustic metamaterials, similar to their optical counterparts, demonstrate anomalous effective elastic properties. Recent developments have shown that coiling up the propagation path of acoustic wave results in effective elastic response of the metamaterial beyond the natural response of its constituent materials. The effective response of metamaterials is generally evaluated using the ‘S’ parameter retrieval method based on amplitude of the waves. The phase of acoustic waves contains information of wave pressure and particle velocity. Here, we show using finite-element methods that phase reversal of transmitted waves may be used to predict extreme acoustic properties in space coiling metamaterials. This change is the difference in the phase of the transmitted wave with respect to the incident wave. This method is simpler when compared with the more rigorous ‘S’ parameter retrieval method. The inferences drawn using this method have been verified experimentally for labyrinthine metamaterials by showing negative refraction for the predicted band of frequencies.

scholarly journals Low-Frequency Broadband Sound Transmission Loss of Infinite Orthogonally Rib-Stiffened Sandwich Structure with Periodic Subwavelength Arrays of Shunted Piezoelectric Patches

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Zhifu Zhang ◽  
Weiguang Zheng ◽  
Qibai Huang
Keyword(s):  
Sandwich Structure ◽  
Transmission Loss ◽  
Virtual Work ◽  
Low Frequency ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Convergence Criterion ◽  
Sound Transmission Loss ◽  
Space Harmonic ◽  
Broadband Sound

This paper studies low-frequency sound transmission loss (STL) of an infinite orthogonally rib-stiffened sandwich structure flexibly connected with periodic subwavelength arrays of finite shunted piezoelectric patches. A complete theoretical model is proposed by three steps. First, the panels and piezoelectric patches on both sides are equivalent to two homogeneous facesheets by effective medium method. Second, we take into account all inertia terms of the rib-stiffeners to establish the governing equations by space harmonic method, separating the amplitude coefficients of the equivalent facesheets through virtual work principle. Third, the expression of STL is reduced. Based on the two prerequisites of subwavelength assumption and convergence criterion, the accuracy and validity of the model are verified by finite element simulations, cited experiments, and theoretical values. In the end, parameters affecting the STL performance of the structure are studied. All of these results show that the sandwich structure can improve the low-frequency STL effectively and broaden the sound insulation bandwidth.

scholarly journals Low-Frequency, Open, Sound-Insulation Barrier by Two Oppositely Oriented Helmholtz Resonators

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1544
Author(s):  
Yi-Jun Guan ◽  
Yong Ge ◽  
Hong-Xiang Sun ◽  
Shou-Qi Yuan ◽  
Xiao-Jun Liu
Keyword(s):  
High Performance ◽  
Low Frequency ◽  
Single Layer ◽  
Sound Insulation ◽  
Architectural Acoustics ◽  
Frequency Sound ◽  
Helmholtz Resonators ◽  
Viscous Loss ◽  
Insulation Effect ◽  
Broadband Sound

In this work, a low-frequency, open, sound-insulation barrier, composed of a single layer of periodic subwavelength units (with a thickness of λ/28), is demonstrated both numerically and experimentally. Each unit was constructed using two identical, oppositely oriented Helmholtz resonators, which were composed of a central square cavity surrounded by a coiled channel. In the design of the open barrier, the distance between two adjacent units was twice the width of the unit, showing high-performance ventilation, and low-frequency sound insulation. A minimum transmittance of 0.06 could be observed around 121.5 Hz, which arose from both sound reflections and absorptions, created by the coupling of symmetric and asymmetric eigenmodes of the unit, and the absorbed sound energy propagating into the central cavity was greatly reduced by the viscous loss in the channel. Additionally, by introducing a multilayer open barrier, a broadband sound insulation was obtained, and the fractional bandwidth could reach approximately 0.19 with four layers. Finally, the application of the multilayer open barrier in designing a ventilated room was further discussed, and the results presented an omnidirectional, broadband, sound-insulation effect. The proposed open, sound-insulation barrier with the advantages of ultrathin thickness; omnidirectional, low-frequency sound insulation; broad bandwidth; and high-performance ventilation has great potential in architectural acoustics and noise control.

Study on dynamic effective parameters of bilayer perforated thin-plate acoustic metamaterials

2020 ◽  
pp. 2150048
Author(s):  
Yicai Xu ◽  
Jiu Hui Wu ◽  
Yongqing Cai
Keyword(s):  
Thin Plate ◽  
Thin Plates ◽  
Formation Mechanisms ◽  
Acoustic Metamaterials ◽  
Effective Parameters ◽  
Retrieval Method ◽  
Acoustic Metamaterial ◽  
Resonance Frequencies ◽  
Wave Normal ◽  
Mass Type

In this paper, dynamic effective parameters of mass-type and stiffness-type bilayer perforated thin-plate acoustic metamaterials (MBPM and SBPM) are investigated by simulations and experiments. Dynamic effective parameters are calculated by the retrieval method, and formation mechanisms of special effective parameters are analyzed by simulated fields. Divergent effective parameters are produced by anti-resonances of coupled perforations or coupled perforated thin-plates, zero effective parameters are produced by resonances of coupled perforated thin-plates. The impacts of perforation parameters on dynamic effective parameters for symmetric and asymmetric BPMs are systemically studied, the simulated and experimental results both show that variation trends of resonance and anti-resonance frequencies of mass-type bilayer perforated thin-plate acoustic metamaterial (MBPM) are different from stiffness-type bilayer perforated thin-plate acoustic metamaterial (SBPM), because perforations mainly change system mass in MBPM and system stiffness in SBPM, respectively. Dynamic effective parameters are bi-anisotropic in asymmetric BPM, and doubly negative effective parameters are achieved by coupled perforations when plan wave normal incident from the side with smaller perforation parameters. A modified retrieval method is proposed to calculate unified effective parameters for the asymmetric BPM, and the unified effective parameters equal to averaged effective parameters of two symmetric BPMs. This work systematically studies dynamic effective parameters of bilayer perforated structures, which has a great guiding significance in design of perforated acoustic devices.

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