A Preliminary Study on the Sound Absorption of Self-Facing Date Palm Fibers

2014 ◽  
Vol 565 ◽  
pp. 25-30 ◽  
Author(s):  
Elwaleed A. Khidir ◽  
N. Nikabdullah ◽  
M.J.M. Nor ◽  
M.F.Mat Tahir ◽  
M.Z. Nuawi
Keyword(s):  
Sound Absorption ◽  
Date Palm ◽  
Perforated Plate ◽  
Low Frequency ◽  
Single Layer ◽  
Absorption Properties ◽  
Date Palm Fibers ◽  
Layer Sample ◽  
Good Improvement ◽  
Preliminary Study

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.

Analysis of Sound Absorption of Date Palm Fibers Based on Flow Resistivity

2013 ◽  
Vol 471 ◽  
pp. 285-290 ◽  
Author(s):  
Elwaleed Awad Khidir ◽  
Mojahed Osman Mohammed Ali ◽  
Mohammed Mustafa Ali ◽  
Mohd Faizal Bin Mat Tahir ◽  
Rozli Zulkifli
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Date Palm ◽  
Single Layer ◽  
Sound Absorption Coefficient ◽  
Low Frequencies ◽  
Palm Fiber ◽  
Date Palm Fibers ◽  
Flow Resistivity ◽  
Fiber Sample

This paper presents a study on the sound absorption properties of a single layer date palm fiber based on the flow resistivity. Experimental measurements were carried out to estimate the flow resistivity value using differential pressure tube. The average diameter of the fibers is 0.462 mm. A date palm fiber sample of 25mm thickness is used in this research. The flow resistivity of the date palm fiber sample was found to be 4.26 kPa.s/m2. The flow resistivity was used to calculate the sound absorption coefficient using Delany and Bazley model. The simulation showed that the values of absorption coefficient are small at low frequencies and rising with increasing frequency. To check the effect of flow resistivity on the sound absorption coefficient Delany and Bazley model was simulated for three different flow resistivity values. The simulation results showed that the sound absorption coefficient increases with the increase of the flow resistivity.

Effect of Density on the Sound Absorption of Date Palm Fibers

2014 ◽  
Vol 663 ◽  
pp. 437-441 ◽  
Author(s):  
Elwaleed Awad Khidir ◽  
Nik Abdullah Nik Mohamed ◽  
Mohd Jailani Mohd Nor ◽  
Mohd Faizal Mat Tahir ◽  
Rozli Zulkifli ◽  
...  
Keyword(s):  
Experimental Study ◽  
Built Environment ◽  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Date Palm ◽  
Absorption Properties ◽  
Palm Fiber ◽  
Date Palm Fibers ◽  
Reduction Coefficient

An experimental study on the effect of panel density on the sound absorption properties of a date palm fiber panel has been presented in this paper. The experiments were carried out by using impedance tube at the Acoustic Lab, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia. The date palm fiber was tested for densities of 77 kg/m3, 100 kg/m3 and 125 kg/m3.The results show that the values of absorption coefficient improve when increasing the density of the panel. Noise reduction coefficient (NRC) was computed to compare the performance of the palm date fiber samples for the different densities. The NRC increases by increasing the density.

A Preliminary Study on the Sound Absorption of Date Palm Fibers

2014 ◽  
Vol 663 ◽  
pp. 406-410
Author(s):  
Elwaleed Awad Khidir ◽  
Nik Abdullah Nik Mohamed ◽  
Mohd Jailani Mohd Nor ◽  
Mohd Faizal Mat Tahir ◽  
Rozli Zulkifli
Keyword(s):  
Sound Absorption ◽  
Date Palm ◽  
Single Layer ◽  
Air Gap ◽  
Constant Thickness ◽  
Frequency Range ◽  
Low Frequencies ◽  
Palm Fiber ◽  
Date Palm Fibers ◽  
Absorption Performance

In this study sound absorption properties of a single layer date palm fiber has been investigated. Experimental measurements were carried out using impedance tube at the acoustic lab, Faculty of Engineering, Universiti Kebangsaan Malaysia. A constant thickness sample was considered in this study.The results show that the values of absorption coefficient are small at low frequencies, rising with increasing frequency but exhibiting a significant peak. The low density of the sample is reflected in the overall sound absorption performance of the date palm fiber. An improvement in the sound absorption in the lower frequency range was achieved by backing the sample with air gap of different thicknesses of 10 mm, 20 mm and 30 mm. The increase in the air gap thickness moved the peaks toward lower frequencies and improved the low frequencies absorption. However, that increase coincided with reduction of absorption in medium frequency range and reduction in the absorption peak. A linear relationship was found between sound absorption peaks and the air gap thickness. The performance of the date palm fiber can be improved by increasing the density of the sample, using different sample thicknesses and adding perforated plates to the date palm fiber panel.

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

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.

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

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.

scholarly journals Experimental and mathematical survey of sound absorption performance of date palm fibers

Heliyon ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. e01977 ◽  
Author(s):  
Ebrahim Taban ◽  
Ali Khavanin ◽  
Ahmad Jonidi Jafari ◽  
Mohammad Faridan ◽  
Ali Kazemi Tabrizi
Keyword(s):  
Sound Absorption ◽  
Date Palm ◽  
Date Palm Fibers ◽  
Absorption Performance

Sound-Absorbing Composites Based on Flax and Polymer Fibers

2015 ◽  
Vol 806 ◽  
pp. 161-166 ◽  
Author(s):  
Nikolay V. Yakimovich ◽  
Sergey N. Bukharov ◽  
Victor V. Kozhushko ◽  
Anastasiya S. Khmara ◽  
Vladimir P. Sergienko
Keyword(s):  
Composite Materials ◽  
Sound Absorption ◽  
Low Frequency ◽  
Single Layer ◽  
Polymer Fibers ◽  
Frequency Range ◽  
Normal Absorption

The paper considers sound absorption of the composite materials, which are based on the natural flax and polymer fibers. The thickness of a single layer of obtained nonwoven composite is about 10 mm. The analysis of absorption dependences is carried out for different thicknesses of the material. It is shown that in the low frequency range the absorption almost linearly increases depending on the thickness. The coefficient of the normal absorption increases with the frequency in the range from 50 Hz up to 1600 Hz. The hot-pressed material can be used for panel production. The sound absorption increases with the thickness of the pressed material. The measurements show the possibilities of application of the composite for the production of the parts of cabs’ interior.

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.

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