scholarly journals Low-frequency acoustic absorption mechanism of a viscoelastic layer with resonant cylindrical scatterers

2013 ◽  
Vol 62 (15) ◽  
pp. 154301
Author(s):  
Yang Hai-Bin ◽  
Li Yue ◽  
Zhao Hong-Gang ◽  
Wen Ji-Hong ◽  
Wen Xi-Sen
Keyword(s):  
Low Frequency ◽  
Viscoelastic Layer ◽  
Acoustic Absorption ◽  
Absorption Mechanism

Low-frequency sound absorption of a tunable multilayer composite structure

2021 ◽  
pp. 107754632110082
Author(s):  
Hanbo Shao ◽  
Jincheng He ◽  
Jiang Zhu ◽  
Guoping Chen ◽  
Huan He
Keyword(s):  
Porous Material ◽  
Absorption Coefficient ◽  
Composite Structure ◽  
Low Frequency ◽  
Acoustic Absorption ◽  
Multilayer Composite ◽  
Absorption Frequency ◽  
Acoustic Absorption Coefficient ◽  
Simulation And Experiment ◽  
Single Material

Our work investigates a tunable multilayer composite structure for applications in the area of low-frequency absorption. This acoustic device is comprised of three layers, Helmholtz cavity layer, microperforated panel layer, and the porous material layer. For the simulation and experiment in our research, the absorber can fulfill a twofold requirement: the acoustic absorption coefficient can reach near 0.8 in very low frequency (400 Hz) and the range of frequency is very wide (400–3000 Hz). In all its absorption frequency, the average of the acoustic absorption coefficient is over 0.9. Besides, the absorption coefficient can be tunable by the scalable cavity. The multilayer composite structure in our article solved the disadvantages in single material. For example, small absorption coefficient in low frequency in traditional material such as microperforated panel and porous material and narrow reduction frequency range in acoustic metamaterial such as Helmholtz cavity. The design of the composite structure in our article can have more wide application than single material. It can also give us a novel idea to produce new acoustic devices.

scholarly journals Low-frequency acoustic absorption of viscoelastic coating with various shapes of scatterers

2012 ◽  
Vol 61 (21) ◽  
pp. 214302
Author(s):  
Lyu Lin-Mei ◽  
Wen Ji-Hong ◽  
Zhao Hong-Gang ◽  
Meng Hao ◽  
Wen Xi-Sen
Keyword(s):  
Low Frequency ◽  
Acoustic Absorption

Low Frequency Absorption of Additively Manufactured Cylinders

2019 ◽  
Author(s):  
Sophie R. Kaye ◽  
Ethan D. Casavant ◽  
Paul E. Slaboch
Keyword(s):  
Low Frequency ◽  
Normal Incidence ◽  
Frequency Noise ◽  
Outer Diameter ◽  
Acoustic Absorption ◽  
Frequency Range ◽  
Large Space ◽  
Low Frequencies ◽  
Cylinder Length ◽  
Hollow Cylinders

Abstract Attenuating low frequencies is often problematic, due to the large space required for common absorptive materials to mitigate such noise. However, natural hollow reeds are known to effectively attenuate low frequencies while occupying relatively little space compared to traditional absorptive materials. This paper discusses the effect of varied outer diameter, and outer spacing on the 200–1600 Hz acoustic absorption of additively manufactured arrays of hollow cylinders. Samples were tested in a 10 cm diameter normal incidence impedance tube such that cylinder length was oriented perpendicular to the incoming plane wave. By varying only one geometric element of each array, the absorption due to any particular parameter can be assessed individually. The tests confirmed the hypothesis that minimizing cylinder spacing and maximizing cylinder diameter resulted in increased overall absorption and produced more focused absorption peaks at specific low frequencies. Wider cylinder spacing produced a broader absorptive frequency range, despite shifting upward in frequency. Thus, manipulating these variables can specifically target absorption for low frequency noise that would otherwise disturb listeners.

New acoustical technology of sound absorption based on reverse horn

2016 ◽  
Vol 30 (34) ◽  
pp. 1650403 ◽  
Author(s):  
Yong Yan Zhang ◽  
Jiu Hui Wu ◽  
Song Hua Cao ◽  
Pei Cao ◽  
Zi Ting Zhao
Keyword(s):  
High Frequency ◽  
Sound Absorption ◽  
Mechanical Energy ◽  
Low Frequency ◽  
Acoustic Energy ◽  
Absorption Mechanism ◽  
Structure Changes ◽  
Potential Applications ◽  
Energy Focusing ◽  
The One

In this paper, a novel reverse horn’s sound-absorption mechanism and acoustic energy focusing mechanism for low-frequency broadband are presented. Due to the alternation of the reverse horn’s thickness, the amplitude of the acoustic pressure propagated in the structure changes, which results in growing energy focused in the edge and in the reverse horn’s tip when the characteristic length is equal to or less than a wavelength and the incident wave is compressed. There are two kinds of methods adopted to realize energy dissipation. On the one hand, sound-absorbing materials are added in incident direction in order to overcome the badness of the reverse horn’s absorption in high frequency and improve the overall high-frequency and low-frequency sound-absorption coefficients; on the other hand, adding mass and film in its tip could result in mechanical energy converting into heat energy due to the coupled vibration of mass and the film. Thus, the reverse horn with film in the tip could realize better sound absorption for low-frequency broadband. These excellent properties could have potential applications in the one-dimensional absorption wedge and for the control of acoustic wave.

scholarly journals Acoustic absorption mechanism and optimization of a rubber slab with cylindrical cavities

2014 ◽  
Vol 63 (13) ◽  
pp. 134303
Author(s):  
Zhao Hong-Gang ◽  
Wen Ji-Hong ◽  
Yang Hai-Bin ◽  
L Lin-Mei ◽  
Wen Xi-Sen
Keyword(s):  
Acoustic Absorption ◽  
Absorption Mechanism ◽  
Cylindrical Cavities

Engineering Coiling‐Up Space Metasurfaces for Broadband Low‐Frequency Acoustic Absorption

2019 ◽  
Vol 13 (12) ◽  
pp. 1900426 ◽  
Author(s):  
Shuang Chen ◽  
Yuancheng Fan ◽  
Fan Yang ◽  
Yabin Jin ◽  
Quanhong Fu ◽  
...  
Keyword(s):  
Low Frequency ◽  
Acoustic Absorption

scholarly journals Structural Design and Sound Absorption Properties of Nitrile Butadiene Rubber-Polyurethane Foam Composites with Stratified Structure

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 946 ◽  
Author(s):  
Xueliang Jiang ◽  
Zhijie Wang ◽  
Zhen Yang ◽  
Fuqing Zhang ◽  
Feng You ◽  
...  
Keyword(s):  
Polyurethane Foam ◽  
Structural Design ◽  
Sandwich Structure ◽  
Sound Absorption ◽  
Low Frequency ◽  
Thickness Ratio ◽  
Butadiene Rubber ◽  
Absorption Mechanism ◽  
Nitrile Butadiene Rubber ◽  
Absorption Performance

Sound absorbing composites with stratified structures, including double-layer and sandwich structures, were prepared through the combination of nitrile butadiene rubber (NBR) and polyurethane foam (PUFM). The effects of the thickness ratio of layers, different stratified structures and the variety of fillers on the sound absorption performance of the NBR-PUFM composites and the sound absorption mechanism were studied. The results show that the NBR-PUFM composite with a sandwich structure and thickness ratio of 1:8:1 displays good sound absorption, which could be improved further by adding fillers. Because the airflow resistivity, resonance absorption, interface dissipation and interface reflection were combined organically in the sandwich structure, the composites show excellent low-frequency sound absorption performance. Moreover, the composite also has advantages in cost and functionalization aspects.

Low-Frequency Acoustic Absorption of 3D Printed Cylinders

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Paul E. Slaboch ◽  
Sophie Kaye ◽  
Ethan Casavant
Keyword(s):  
Low Frequency ◽  
Normal Incidence ◽  
Frequency Noise ◽  
Outer Diameter ◽  
Acoustic Absorption ◽  
Large Space ◽  
Low Frequencies ◽  
Cylinder Length ◽  
3D Printed ◽  
Hollow Cylinders

Abstract Attenuating low-frequency sound is often problematic, due to the large space required for common absorptive materials to mitigate such noise. However, natural hollow reeds are known to effectively attenuate low frequencies while occupying relatively little space compared to traditional absorptive materials. The present study determines the effect of varied outer diameter and outer spacing on the 200–1600 Hz acoustic absorption of 3D printed arrays of hollow cylinders. Samples were tested in a 100-mm diameter normal incidence impedance tube such that cylinder length was oriented perpendicular to the incoming plane wave. By varying only one geometric element of each array, the absorption due to any parameter can be assessed individually. It was found that minimizing cylinder spacing and maximizing cylinder diameter resulted in increased overall absorption and produced more focused absorption peaks at specific low frequencies. Wider cylinder spacing produced a broader absorptive frequency range, despite shifting upward in frequency. Thus, manipulating these variables can specifically target absorption for low-frequency noise that would otherwise disturb listeners.

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