Design of multilayer sound-absorbing composites with excellent sound absorption properties at medium and low frequency via constructing variable section cavities

Sound absorption of self-facing natural date palm fibershas been investigated.A single layer sample of the fibers was tested for its sound absorption properties. The sample was then faced with the originally date palm fiber netted structure. Experimental measurements were conducted on the impedance tube at the acoustic lab, Faculty of Engineering, UniversitiKebangsaan Malaysia, to determine the sound absorption coefficient.The single layer was also tested using an aluminum perforated plate, as facing, for comparison purposes.The results show a good improvement in the sound absorption for the self-facing panel for the whole frequency range. However, when using the aluminum perforated panel an improvement in the sound absorption was observed only above 2500 Hz. The effect of introducing air gap thickness was studied. The results show improvement for the sound absorption the low frequency.

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Analysis of Sound Absorption Properties of Three-Leaf Microperforated Panel Absorbers without a Rigid Backing

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.937.465 ◽

2014 ◽

Vol 937 ◽

pp. 465-471

Author(s):

Xiao Ling Gai ◽

Xian Hui Li ◽

Rui Wu ◽

Bin Zhang ◽

Jun Juan Zhao

Keyword(s):

Sound Absorption ◽

Low Frequency ◽

Wide Frequency Range ◽

Structure Design ◽

Frequency Region ◽

Theoretical Development ◽

Frequency Range ◽

Absorption Properties ◽

High Frequency Region ◽

Energy Dissipated

Microperforated panel (MPP) absorbers have been developed rapidly and used in many fields in recent years. First, based on the Maa’s theory, the theoretical development of MPP is reviewed in this paper. Furthermore, structure design and processing technology of MPP are introduced. Finally, the further development of MPP is discussed. Based on the MPP theory and electro-acoustical equivalent circuit principle, sound absorption properties of three-leaf microperforated panel (TMPP) absorbers without a rigid backing are studied to broaden the sound absorption bandwidth of MPP structure. Simulation results show that TMPP absorbers without a rigid backing have two resonance peaks and the energy dissipated coefficient remains constant in the low frequency range. The resonance frequency moves toward low frequency region with the increasing of the distance, thickness and pore diameter of MPP and moves toward high frequency region with the increasing of the perforation when other parameters keep invariant. The energy dissipated coefficient more than 0.5 over 8 octaves by choosing proper parameters. In conclusion, TMPP absorbers without a rigid backing have good sound absorption properties in a wide frequency range.

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Sound absorption properties of multi-layer structural composite materials based on waste corn husk fibers

Journal of Engineered Fibers and Fabrics ◽

10.1177/1558925020910861 ◽

2020 ◽

Vol 15 ◽

pp. 155892502091086

Author(s):

Lihua Lyu ◽

Jing Lu ◽

Jing Guo ◽

Yongfang Qian ◽

Hong Li ◽

...

Keyword(s):

Composite Materials ◽

Absorption Coefficient ◽

Sound Absorption ◽

Low Frequency ◽

Sound Absorption Coefficient ◽

Absorption Properties ◽

Cavity Depth ◽

Air Cavity ◽

Corn Husk ◽

Structural Composite

In order to find a reasonable way to use the waste corn husk, waste degummed corn husk fibers were used as reinforcing material in one type of composite material. And polylactic acid particles were used as matrix material. The composite materials were prepared by mixing and hot-pressing process, and they were processed into the micro-slit panel. Then, the multi-layer structural sound absorption composite materials were prepared sequentially by micro-slit panel, air cavity, and flax felt. Finally, the sound absorption properties of the multi-layer structural composite materials were studied by changing flax felt thickness, air cavity depth, slit rate, and thickness of micro-slit panel. As the flax felt thickness varied from 0 to 10 mm in 5 mm increments, the peak of sound absorption coefficient shifted to low frequency. The sound absorption coefficient in the low frequency was improved with the air cavity depth varied from 0 to 10 mm in 5 mm increments. With the slit rate increased from 3% to 7% in 2% increments, the peak of sound absorption coefficient shifted to high frequency. With the thickness of micro-slit panel increased from 2 to 6 mm in 2 mm increments, the sound absorption bandwidth was broaden, and the peak of sound absorption coefficient was increased and shifted to low frequency. Results showed that the highest sound absorption coefficient of the multi-layer structural composite materials was about 1 under the optimal process conditions.

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Sound-Absorption Properties of Kapok Fiber Nonwoven Fabrics at Low Frequency

Journal of Natural Fibers ◽

10.1080/15440478.2014.919891 ◽

2015 ◽

Vol 12 (4) ◽

pp. 311-322 ◽

Cited By ~ 12

Author(s):

Xueting Liu ◽

Xiong Yan ◽

Li Li ◽

Huiping Zhang

Keyword(s):

Sound Absorption ◽

Low Frequency ◽

Absorption Properties ◽

Kapok Fiber ◽

Nonwoven Fabrics

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Preparation and Low Frequency Sound Absorption Properties of Silicate Composite Material

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.482-484.1338 ◽

2012 ◽

Vol 482-484 ◽

pp. 1338-1342 ◽

Cited By ~ 1

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.

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Sound-Absorbing Properties of Kapok Fiber Nonwoven Composite at Low-Frequency

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.821-822.329 ◽

2013 ◽

Vol 821-822 ◽

pp. 329-332 ◽

Cited By ~ 1

Author(s):

Xue Ting Liu ◽

Li Li ◽

Xiong Yan ◽

Hui Ping Zhang

Keyword(s):

Bulk Density ◽

Sound Absorption ◽

Natural Fiber ◽

Low Frequency ◽

Polyester Fiber ◽

Physical Parameters ◽

Absorption Properties ◽

Kapok Fiber ◽

Absorbing Materials ◽

Properties Of Composites

More and more concern for environmental problems has led public to use natural and environmentally benign sound-absorbing materials. In this study, the sound-absorbing nonwoven composites based on kapok fiber and hollow polyester fiber were developed and sound absorption properties of kapok fiber nonwoven composites were investigated in the low frequency region of 100-500 Hz using the impedance tube method. The poor sound-absorbing at low-frequency is one of the difficult problems that urgently need to be solved in fibrous sound-absorbing materials. The effects of physical parameters, including bulk density and thickness, and depth of back cavity on sound absorption properties of composites were studied. Increasing of the bulk density, thickness and depth of back cavity is contribute to improve sound absorption properties of composites at low frequency. The comparisons of kapok fiber with polypropylene (PP) fiber and hollow polyester fiber indicated that as a natural fiber, kapok fiber had a superior acoustical properties at low frequency.

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An innovative composite plywood for the acoustic improvement of small closed spaces

Holzforschung ◽

10.1515/hf-2016-0122 ◽

2017 ◽

Vol 71 (6) ◽

pp. 521-526

Author(s):

Francesco Negro ◽

Corrado Cremonini ◽

Marco Fringuellino ◽

Roberto Zanuttini

Keyword(s):

Sound Absorption ◽

Resonance Effect ◽

Low Frequency ◽

Frequency Range ◽

Honeycomb Core ◽

Final Size ◽

Absorption Properties ◽

Reverberation Chamber ◽

The Core ◽

Dining Room

Abstract Poor acoustics is a common problem in many small closed rooms such as offices or dining rooms. Sound absorbing panels used as wall or ceiling coverings can be a remedy. In the present paper, the sound absorption properties of a composite made of two plywood skins bonded to an inner honeycomb core of plywood cells, designed by the authors in a previous study, were improved by drilling the surfaces. The holes communicate with the void cells of the core, activating the Helmholtz resonance effect. The acoustic behavior of small specimens and final-size samples are described, which were also tested in a reverberation chamber and in a real dining room. The developed lightweight composite plywood achieved αmax 0.90 values (maximal sound absorption coefficients) around 400 Hz, i.e. in the low frequency range, resulting in being well suited for various acoustic improvements.

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Preparation and sound absorption properties of barium titanate/nitrile butadiene rubber-polyurethane foam composites with stratified structure

RSC Advances ◽

10.1039/c8ra03330g ◽

2018 ◽

Vol 8 (37) ◽

pp. 20968-20975 ◽

Cited By ~ 2

Author(s):

Xueliang Jiang ◽

Zhijie Wang ◽

Zhen Yang ◽

Fuqing Zhang ◽

Feng You ◽

...

Keyword(s):

Barium Titanate ◽

Polyurethane Foam ◽

Double Layer ◽

Sound Absorption ◽

Low Frequency ◽

Butadiene Rubber ◽

Absorption Properties ◽

Frequency Sound ◽

Pu Foam ◽

Absorption Performance

BT/NBR-PU foam composites with two different stratified structures including double-layer and alternating multilayered have excellent low-frequency sound absorption performance.

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Research on sound absorption properties of hydrogenated carboxyl nitrile rubber/four-hole hollow polyester fibre composites

Industria Textila ◽

10.35530/it.072.02.1547 ◽

2021 ◽

Vol 72 (02) ◽

pp. 117-125

Author(s):

JIE HONG

Keyword(s):

Absorption Coefficient ◽

Sound Absorption ◽

Polyester Fibre ◽

Low Frequency ◽

Nitrile Rubber ◽

Engineering Practice ◽

Negative Effects ◽

Absorption Properties ◽

The Matrix ◽

Absorption Performance

A series composite was prepared by adding hydrogenated carboxyl nitrile rubber (abbreviated HXNBR) as the matrix and four-hole hollow polyester (abbreviated FHHPF) as the reinforcement. The sound absorption properties of these composites were studied. The results show that with the increasing of FHHPF quantity, the storage modulus increases and the loss factor decreases gradually. On the contrary, the sound absorption performance of the composite was improved continuously. Composite with 40% FHHPF in 1 mm thickness is the best. The sound absorption coefficient reached to 0.651 at 2500 Hz and the effective frequency range of absorption coefficient above 0.2 was 1750-2500 Hz. When the amount of FHHPF increased to 50%, negative effects of overuse shown up, that led to the decreasing of the sound absorption property. With a constant mass ratio 70/30 of HXNBR/FHHPF composite, the sound absorption performance can be enhanced by changing its thickness. However, the improvement was smaller after the thickness increased to 2 mm. When increasing the thickness above 2 mm, the improvement of sound absorption performance tended to move to the middle and low frequency. In the meantime, the tensile mechanical properties of the composite were significantly improved by adding FHHPF. Tensile tenacity was improved greatly and the breaking elongation is significantly decreased. The deformation of the composite was smaller and more stable, which was beneficial for the actual engineering practice.

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