scholarly journals Design of Multiple Parallel-Arranged Perforated Panel Absorbers for Low Frequency Sound Absorption

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2099
Author(s):  
Xin Li ◽  
Qianqian Wu ◽  
Ludi Kang ◽  
Bilong Liu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Normal Wave ◽  
Low Frequency ◽  
Approximation Model ◽  
Low Frequencies ◽  
Absorption Bandwidth ◽  
Frequency Sound ◽  
Electrical Analogy ◽  
Wave Incidence

A particular structure that consists of four parallel-arranged perforated panel absorbers (PPAs) is proposed for the low frequency sound absorption within a constraint space. The apertures of the perforated panels are set to ≥1.5 mm, and the number of orifices is much less and therefore easier to be produced in comparison with that of the micro perforated panel (MPP). A simple approximation model by using acoustic-electrical analogy is described to calculate the sound absorption coefficient of such device subject to normal wave incidence. Theoretical and experimental results demonstrate that the device can provide more than one octave sound absorption bandwidth at low frequencies.

scholarly journals Hybrid acoustic metamaterial as super absorber for broadband low-frequency sound

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Yufan Tang ◽  
Shuwei Ren ◽  
Han Meng ◽  
Fengxian Xin ◽  
Lixi Huang ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Low Frequency ◽  
Functional Materials ◽  
Theoretical Method ◽  
Acoustic Metamaterials ◽  
Mechanical Stiffness ◽  
Acoustic Metamaterial ◽  
Frequency Sound

Abstract A hybrid acoustic metamaterial is proposed as a new class of sound absorber, which exhibits superior broadband low-frequency sound absorption as well as excellent mechanical stiffness/strength. Based on the honeycomb-corrugation hybrid core (H-C hybrid core), we introduce perforations on both top facesheet and corrugation, forming perforated honeycomb-corrugation hybrid (PHCH) to gain super broadband low-frequency sound absorption. Applying the theory of micro-perforated panel (MPP), we establish a theoretical method to calculate the sound absorption coefficient of this new kind of metamaterial. Perfect sound absorption is found at just a few hundreds hertz with two-octave 0.5 absorption bandwidth. To verify this model, a finite element model is developed to calculate the absorption coefficient and analyze the viscous-thermal energy dissipation. It is found that viscous energy dissipation at perforation regions dominates the total energy consumed. This new kind of acoustic metamaterials show promising engineering applications, which can serve as multiple functional materials with extraordinary low-frequency sound absorption, excellent stiffness/strength and impact energy absorption.

Broadening of the Sound Absorption Bandwidth of the Perforated Panel Using a Membrane-Type Resonator

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Xuezhi Zhu ◽  
Zhaobo Chen ◽  
Yinghou Jiao ◽  
Yanpeng Wang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Degrees Of Freedom ◽  
Low Frequency ◽  
Absorption Capacity ◽  
Sound Absorption Coefficient ◽  
Sound Waves ◽  
Frequency Range ◽  
Absorption Bandwidth ◽  
Membrane Type

In order to broaden the sound absorption bandwidth of a perforated panel in the low frequency range, a lightweight membrane-type resonator is installed in the back cavity of the perforated panel to combine into a compound sound absorber (CSA). Because of the great flexibility, the membrane-type resonator can be vibrated easily by the incident sound waves passing through the holes of the perforated panel. In the low frequency range, the membrane-type resonator and the perforated panel constitute a two degrees-of-freedom (DOF)-resonant type sound absorption system, which generates two sound absorption peaks. By tuning the parameters of the membrane type resonator, a wide frequency band having a large sound absorption coefficient can be obtained. In this paper, the sound absorption coefficient of CSA is derived analytically by combining the vibration equation of the membrane-type resonator with the acoustic impedance equation of the perforated panel. The influences of the parameters of the membrane-type resonator on the sound absorption performance of the CSA are numerically analyzed. Finally, the wide band sound absorption capacity of the CSA is validated by the experimental test.

scholarly journals A Perforated Plate with Stepwise Apertures for Low Frequency Sound Absorption

2021 ◽  
Vol 11 (13) ◽  
pp. 6180
Author(s):  
Xin Li ◽  
Bilong Liu ◽  
Chong Qin
Keyword(s):  
3D Printing ◽  
Sound Absorption ◽  
Numerical Models ◽  
Characteristic Impedance ◽  
Perforated Plate ◽  
Low Frequency ◽  
Low Frequencies ◽  
Perforated Plates ◽  
Absorption Bandwidth ◽  
Acoustic Resistance

A perforated plate with stepwise apertures (PPSA) is proposed to improve sound absorption for low frequencies. In contrast with an ordinary perforated plate with insufficient acoustic resistance and small acoustic mass, the perforated plate with stepped holes could match the acoustic resistance of air characteristic impedance and also moderately increase acoustic mass especially at low frequencies. Prototypes made by 3D printing technology are tested in an impedance tube. The measured results agree well with that of prediction through theoretical and numerical models. In addition, an absorber array of perforated plates with stepwise apertures is presented to extend the sound absorption bandwidth due to the introduced multiple local resonances.

Preparation and Low Frequency Sound Absorption Properties of Silicate Composite Material

2012 ◽  
Vol 482-484 ◽  
pp. 1338-1342 ◽  
Author(s):  
Long Gui Peng ◽  
Guang Cheng Zhang ◽  
Xing Guo Yu ◽  
Ying Li
Keyword(s):  
Composite Material ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
High Efficiency ◽  
Low Frequency ◽  
Thin Wall ◽  
Absorption Properties ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Frequency Sound

The silicate based low frequency sound absorption composite material was prepared with powdery polymethacrylimide (PMI) foam as filler. The effects of the amounts of PMI and pore-forming agent, and water-cement ratio on sound absorption properties of composite material were researched. Sound absorption coefficient was characterized by standing wave tube, and micro structure of composite material was analyzed by scanning electron microscope. The results show that: when the amounts of PMI and pore-forming agent are 2.5wt% and 0.04wt%, respectively, and water cement ratio is 0.55, the average value of the absorption coefficient on the sound （≤1000Hz）can up to 0.35. Resonating sound absorption structure formed by micro pore of the silicate and thin wall cavity of PMI in composite materials is beneficial to high efficiency absorption to low frequency sound.

Influences of the Air Layer with Irregular Shape to the Absorbing Constructions

2011 ◽  
Vol 343-344 ◽  
pp. 289-295
Author(s):  
Kai Hua Liu ◽  
Rong Ping Lai ◽  
Chuan Wen Chou
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Low Frequency ◽  
Past Research ◽  
Irregular Shape ◽  
Interior Space ◽  
Air Cavity ◽  
Low Frequencies ◽  
The Subject ◽  
Absorption Characteristics

Air layer with irregular shape in sound absorbing structure is formed by different structure mode of materials. With building multiform interior space by materials and structure mode, it makes the shape of air layer between the facing and the structure of building to be irregular shape.According to related study of absorbing structure, it shows less information about the influence of air layer with irregular shape. The factors of sound absorption of absorbing structure were focused on absorbing structure which facing paralleled structure of building in past research. For searching the influence of sound absorption of absorbing structure caused by the air layer with irregular shape, the subject in this study is set as the air layer with irregular shape which facing tilts with single-axis. The factors of air layer with irregular shape are the angle between tilting facing and horizontal face, the length of span of tilting facing, and if the setting is that the air layer is divided into several parts not to be interlinked. By these factors the sound absorption characteristics of air layer with irregular shape are shown.In the other point of effects of absorption coefficient causing by setting of air cavity, both panel and perforated panel structure the influences are influenced mainly at low frequency, especially at 200 Hz. Whether the air cavity is set or not, the panel structure reveals less influences and the absorption coefficient reduces as increasing of span at low frequencies.

scholarly journals Enhanced Low-Frequency Sound Absorption of a Porous Layer Mosaicked with Perforated Resonator

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 223
Author(s):  
Xin Li ◽  
Bilong Liu ◽  
Qianqian Wu
Keyword(s):  
Porous Material ◽  
Absorption Coefficient ◽  
Porous Layer ◽  
Acoustic Impedance ◽  
Sound Absorption ◽  
Perforated Plate ◽  
Low Frequency ◽  
Sound Absorption Coefficient ◽  
Frequency Sound ◽  
Two Samples

A composite structure composed of a porous-material layer mosaicked with a perforated resonator is proposed to improve the low-frequency sound absorption of the porous layer. This structure is investigated in the form of a porous-material matrix (PM) and a perforated resonator (PR), and the PR is a thin perforated plate filled with porous material in its back cavity. Theoretical and numerical models are established to predict the acoustic impedance and sound absorption coefficient of the proposed structure, and two samples made of polyurethane and melamine, respectively, are tested in an impedance tube. The predicted results are consistent with that of the measured. Compared with a single porous layer with the same thickness, the results show that the designed structure provides an additional sound absorption peak at low frequencies. The proposed structure is compact and has an effective absorption bandwidth of more than two octaves especially below the frequency corresponding to 1/4 wavelength. A comparison is also made between the sound absorption coefficients of the proposed structure and a classical micro-perforated plate (MPP), and the results reveal equivalent acoustic performance, suggesting that it can be used as an alternative to the MPP for low–mid frequency sound absorption. Moreover, the influences of the main parameters on the sound absorption coefficient of PPCS are also analyzed, such as the hole diameter, area ratio, flow resistance, and porous-material thickness in the PR. The mechanism of sound absorption is discussed through the surface acoustic impedance and the distributions of particle velocity and sound pressure at several specific frequencies. This work provides a new idea for the applications of the thin porous layer in low- and medium-frequency sound absorption.

scholarly journals Error Sensing Strategy for Active Control of Low-Frequency Sound Absorption of Micro-Perforated Panel Absorber by Using a Point Force Controlled Thin Plate

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Xiyue Ma ◽  
Kean Chen ◽  
Lei Wang ◽  
Yang Liu
Keyword(s):  
Absorption Coefficient ◽  
Active Control ◽  
Surface Impedance ◽  
Sound Absorption ◽  
Low Frequency ◽  
Point Force ◽  
Sound Absorption Coefficient ◽  
Error Signal ◽  
Frequency Sound ◽  
Highly Correlated

This paper presents an analytical investigation on constructing an error sensing strategy of a new type of active MPPA. The proposed active MPPA is composed of MPP, air cavity, and point force-controlled backing panel, which can actively improve the low-frequency sound absorption of the MPPA. Constructing an appropriate error sensing strategy for obtaining an error signal that is highly correlated with the sound absorption coefficient of the active MPPA is a key problem encountered in practical implementation. The theoretical model of the active MPPA is firstly established using the modal analysis approach. Then, the active control performance and surface impedance characteristics in the controlled condition are analyzed in detail. Finally, the error sensing strategy of the active MPPA is constructed by measuring the surface average impedance ratio with an acoustic vector sensor (AVS). Simulation results show that, due to the antisymmetric property of the vibration of the backing panel on the resonant frequency, the surface impedance of the active MPPA after control also has symmetry or antisymmetry properties. Hence, the surface average impedance ratio of the active MPPA can be measured by using the limited number of acoustic vector sensors (sensing pressure and particle velocity). This variable is also highly correlated with the sound absorption coefficient of the active MPPA and thus can be used to construct the cost function (error signal). The active control result obtained by the proposed error sensing strategy is in good agreement with the theoretically optimal result, which validates the feasibility of this approach.

scholarly journals STUDY AND ANALYSIS ON SOUND ABSORBING AND NOISE REDUCING PERFORMANCE OF TIMBER CONSTRUCTION WALL BASED ON ACOUSTIC SPIRAL MATASURFACE

Wood Research ◽  
2021 ◽  
Vol 66 (3) ◽  
pp. 341-352
Author(s):  
Haiyan Fu ◽  
Xinyue Zhao ◽  
Patrick Adjei ◽  
Zheng Wang ◽  
Xiaoli Wu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Low Frequency ◽  
Sound Absorption Coefficient ◽  
Impedance Tube ◽  
Frequency Sound ◽  
Timber Construction ◽  
Absorption Performance ◽  
Impedance Tube Method ◽  
Structural Layer

Based on acoustic spiral metasurface, a spiral structural layer was designed to apply to timber construction interior wall. The sound absorption coefficient was measured by impedance tube method and compared with Helmholtz resonance structural layer, solid structural layer and air layer in traditional wall. The results show that the combination of the spiral structural layer and the wall can optimize the sound absorption performance of the wall in the medium and low frequency. Without reducing the overall sound-absorbing performance of the wall, can achieve perfect sound absorption in some medium and low frequency sound bands.

scholarly journals Investigation of Acoustic Properties on Wideband Sound-Absorber Composed of Hollow Perforated Spherical Structure with Extended Tubes and Porous Materials

2020 ◽  
Vol 10 (24) ◽  
pp. 8978
Author(s):  
Dengke Li ◽  
Zhongcheng Jiang ◽  
Lin Li ◽  
Xiaobo Liu ◽  
Xianfeng Wang ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Three Dimensional ◽  
Low Frequency ◽  
Acoustic Properties ◽  
Low Frequencies ◽  
Frequency Sound ◽  
Sound Absorber ◽  
Spherical Structure ◽  
Absorption Performance ◽  
Melamine Foam

Traditional porous media such as melamine foam absorb sound due to their three-dimensional porous struts. However, the acoustic properties at low frequencies are greatly related to its thickness. In this paper, a novel type of thin and lightweight sound absorber composed of melamine foam and hollow perforated spherical structure with extended tubes (HPSET) is introduced to enhance the sound absorption performance at low frequencies. A theoretical model for the normal absorption coefficient of the HPSET with melamine foam is established. Good agreements are observed between the simulated and the experimental results. Compared with the virgin melamine foam, the proposed absorber can greatly improve the low-frequency sound absorption and retain the mid- to high-frequency sound absorption, while the thickness of the proposed absorber is less than 1/28 of the wavelength.

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