The Effect pf Non-Homogenous Perforation Pattern on Sound Absorption Bandwidth of Micro-Perforate Panel

In this paper, a nonlinear electroacoustic absorber based on a tunable loudspeaker is proposed to broaden its sound absorption bandwidth. The main mechanism is a nonlinear circuit is coupled at loudspeaker's terminal. A series of theoretical analysis and simulation work are carried out in this paper. The equivalent model is composed of a linear term describing the loudspeaker and a nonlinear term of a coupled Duffing-van Der Pol bistable circuit. The invariant manifold method is used to solve different time scales. The analysis and simulation results show that the nonlinear circuit can widen the frequency bandwidth of the structure.

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

Journal of Vibration and Acoustics ◽

10.1115/1.4038942 ◽

2018 ◽

Vol 140 (3) ◽

Cited By ~ 4

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.

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A Perforated Plate with Stepwise Apertures for Low Frequency Sound Absorption

Applied Sciences ◽

10.3390/app11136180 ◽

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.

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

Materials ◽

10.3390/ma12132099 ◽

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.

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Acoustic performance of countersunk micro-perforated panel in multilayer porous material

Building Acoustics ◽

10.1177/1351010x19886588 ◽

2019 ◽

Vol 27 (1) ◽

pp. 3-20 ◽

Cited By ~ 1

Author(s):

L Yuvaraj ◽

S Jeyanthi

Keyword(s):

Additive Manufacturing ◽

Porous Material ◽

Porous Materials ◽

Transfer Matrix Method ◽

Sound Absorption ◽

Integration Method ◽

Absorption Bandwidth ◽

Acoustic Performance ◽

Hole Profile ◽

Materials Used

This study investigates the acoustic performance of a countersunk micro-perforated panel, along with two distinct porous materials used in a multilayer porous absorber configuration. Additive manufacturing is applied to create sub-millimeter perforation with different hole spacings on polymer micro-perforated panels. Experiments are conducted in an impedance tube, in which the effects of the perforation ratio, air gap, and varying porous layer configurations on the sound absorption capabilities are investigated. For validation, considering the converging hole profile in the micro-perforated panel, an integration method with end correction is used to calculate the tapered section impedance, and the traditional Maa theory is used for the uniform hole. The theoretical impedance of the multilayer absorber is calculated using the transfer matrix method and subsequently compared to the experimental results. The results demonstrate that the countersunk hole micro-perforated panel exhibits a significant improvement in sound absorption, and the introduction of porous materials extends the sound absorption bandwidth. Furthermore, the results indicate that the sound absorption capability depends on the porous material placement in the multilayer absorber configuration.

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