scholarly journals Sound Absorption Performance of the Poplar Seed Fiber/PCL Composite Materials

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1465 ◽  
Author(s):  
Yingjie Liu ◽  
Lihua Lyu ◽  
Jing Guo ◽  
Ying Wang
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Fractal Dimensions ◽  
Sound Absorption Coefficient ◽  
Process Conditions ◽  
Pressing Method ◽  
Absorption Frequency ◽  
Absorption Performance

Composite materials were prepared by the hot pressing method using poplar seed fibers and polycaprolactone (PCL) as the raw materials to solve the problems related to the recycling of waste fibers. The effects of mass fraction of poplar seed fibers, the volume density, and thickness on the sound absorption performance of the resulting composite materials were studied. The sound absorption coefficient curves of the composite material were obtained by the acoustic impedance transfer function method. The sound absorption coefficient of the composite material that was prepared under the optimal process conditions was higher than 0.7, and the effective sound absorption frequency band was wide. According to the box counting dimension method, which is based on the fractal theory, the fractal dimensions of the composite materials were calculated while using the Matlab program. The relationships between the fractal dimensions and the volume densities, mass fractions of poplar seed fibers, and thicknesses of the composite materials were also analyzed. Subsequently, the quantitative relationship between the fractal dimension and the sound absorption property parameters of the composite material was established in order to provide a theoretical basis for the design of the sound absorption composite material.

scholarly journals Sound-Absorption Performance and Fractal Dimension Feature of Kapok Fibre/Polycaprolactone Composites

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1000 ◽  
Author(s):  
Lihua Lyu ◽  
Duoduo Zhang ◽  
Yuanyuan Tian ◽  
Xinghai Zhou
Keyword(s):  
Composite Material ◽  
Fractal Dimension ◽  
Absorption Coefficient ◽  
Mass Fraction ◽  
Sound Absorption ◽  
Volume Density ◽  
Sound Absorption Coefficient ◽  
Pressing Method ◽  
Absorption Frequency ◽  
Absorption Performance

This article introduces a kind of composite material made of kapok fibre and polycaprolactone by the hot-pressing method. The effects of volume density, mass fraction of kapok fibre, and thickness on the sound-absorption performance of composites were researched using a single-factor experiment. The sound-absorption performance of the composites was investigated by the transfer function method. Under the optimal process parameters, when the density of the composite material was 0.172 g/cm3, the mass fraction of kapok was 40%, and the thickness was 2 cm, the composite material reached the maximum sound-absorption coefficient of 0.830, and when the sound-absorption frequency was 6300 Hz, the average sound-absorption coefficient was 0.520, and the sound-absorption band was wide. This research used the box dimension method to calculate composites’ fractal dimensions by using the Matlab program based on the fractal theory. It analysed the relationships between fractal dimension and volume density, fractal dimension and mass fraction of kapok fibre, and fractal dimension and thickness. The quantitative relations between fractal dimension and maximum sound-absorption coefficient, fractal dimension, and resonant sound-absorption frequency were derived, which provided a theoretical basis for studying sound-absorption performance. The results showed that kapok fibre/polycaprolactone composites had strong fractal characteristics, which had important guiding significance for the sound-absorption performance of kapok fibre composites.

scholarly journals Sound Absorption Performance of Sugar Palm Trunk Fibers

2019 ◽  
Vol 130 ◽  
pp. 01003
Author(s):  
Anditya Endar Prabowo ◽  
Kuncoro Diharjo ◽  
Ubaidillah ◽  
Iwan Prasetiyo
Keyword(s):  
Absorption Coefficient ◽  
Bulk Density ◽  
Sound Absorption ◽  
Random Noise ◽  
Air Gap ◽  
Sound Absorption Coefficient ◽  
Low Frequencies ◽  
Central Java ◽  
Absorption Performance ◽  
Small Medium Enterprises

The purpose of this research is to investigate the effect of bulk density, thickness, and air gap to sound absorption performance on absorber based sugar palm trunk fibers. The fibers were obtained from solid waste on Small-Medium Enterprises of sago flour processing in Klaten, Central Java, Indonesia. The absorber specimens were formed from the fibers using a simple press molding in an oven at 150 °C. According to ISO 10534-2, the absorber samples were tested using two microphones impedance tube with random noise source to get the curve of the sound absorption coefficient. The result shows that the absorption performance can be improved by increasing bulk density and increasing of sample thickness. Especially at low frequencies, improvement of the sound absorption coefficient can be achieved (NAC > 0.8) by applying the air gap behind the sample. The best performance of absorber based sugar palm trunk fiber can be achieved for (1 000 to 6 000) Hz range frequency.

Application of In Situ Method for Measuring Sound Absorption Coefficient of Direct Piercing Carved Wood Panel with Daun sireh Motif

2013 ◽  
Vol 471 ◽  
pp. 273-278
Author(s):  
Mohd Zamri Bin Jusoh ◽  
Mohamad Ngasri Dimon ◽  
Nazli Bin Che Din ◽  
Toru Otsuru ◽  
You Kok Yeow
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Wood Panel ◽  
Natural Sunlight ◽  
Absorption Performance ◽  
Air Circulation ◽  
Lower Frequencies

An application of In-Situ method of measuring sound absorption coefficient on the surface of direct piercing carved wood panel using the concept of ensemble averaged is discussed. The method offer an easier way to measure the absorption performance for each individual aperture of carved wood panel with floral pattern which was replicated from one of the oldest mosque, namely Masjid Abidin located in Terengganu, Malaysia. Two pieces of 20 mm thick of cengal wood (Neobalanocarpus heimii) with 30% and 40% perforation ratio were respectively measured in a reverberation room in order to determine the value of . At lower frequencies (0.1 kHz-1.5 kHz), the measured values of for both direct piercing carved wood panel with floral pattern (Daun Sireh motif) are shown that the sound absoption for both direct piercing carved wood panel are in perform level. From the measurements, clearly, the installation of the direct piercing carved wood panel with floral pattern (Daun Sireh motif) in the Masjid Abidin can provide better air circulation and additional natural sunlight, as well as better sound intelligibility inside the building.

scholarly journals Effect of Thickness and Perforation Size on the Acoustic Absorption Performance of a Micro-Perforated Panel

2021 ◽  
Vol 335 ◽  
pp. 03016
Author(s):  
Yi-San Wong ◽  
Vignesh Sekar ◽  
Se Yong Eh Noum ◽  
Sivakumar Sivanesan
Keyword(s):  
Absorption Coefficient ◽  
Urban Areas ◽  
Sound Absorption ◽  
Rapid Development ◽  
Noise Pollution ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Acoustic Absorption ◽  
Psychological Disturbance ◽  
Absorption Performance

In current times, noise pollution is especially apparent in urban areas due to rapid development in transportation, industrialization, and urbanization. The worsening noise pollution is detrimental to human health and behaviour as it can contribute to disorders and psychological disturbance. Thus, noise regulation is crucial and must be addressed with immediate effect. Micro-perforated panels (MPP) can be a potential solution to mitigate noise on a commercial scale. Researchers have addressed the mechanics behind the enhancement of acoustic absorption through micro-perforation and some suggestions have been made, such as the effect of structural variation on sound absorption performance. Hence, this research aims at optimizing the sound absorption performance of an MPP by determining the connection between thickness and perforation size with sound absorption coefficient. Three cases were considered: (i) varying perforation size, (ii) varying thickness, and (iii) varying perforation size and thickness simultaneously. Based on the Maa prediction model, the sound absorption performance for all three cases have been simulated through the MATLAB software. Results show that the increase in both thickness and perforation size together increases the peak value of sound absorption coefficient (SAC). It also shifts the peak towards the higher frequency region and narrows the bandwidth. The findings of this study indicate the potential of thick MPPs as commercial sound absorbers by adjusting the size of perforations. Thicker and sturdier MPPs with optimal acoustic resistance and reactance can act as reliable sound absorbers for sound insulation purposes.

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 Building Sound Absorption Performance Model of Porous Glass Based on GRNN

2019 ◽  
Vol 37 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Xubo Zhang ◽  
Ying Xu ◽  
Tingying Zhang ◽  
Guodong Li
Keyword(s):  
Absorption Coefficient ◽  
Porous Glass ◽  
Sound Absorption ◽  
Performance Model ◽  
Sound Absorption Coefficient ◽  
Average Error ◽  
Generalized Regression Neural Network ◽  
Prediction Curve ◽  
Absorption Performance ◽  
Two Parameters

The generalized regression neural network (GRNN) model of sound absorption coefficient of porous glass was built on data from 16 groups gained by experiments, where 12 groups were randomly selected as trained samples and the other 4 groups were as tested ones. This GRNN model which has two parameters, porosity and thickness as the inputs, was set the maximum iteration number 20, getting the optimal trained spread parameter σ=0.1. The results showed that the average error of this model was 0.003, and this model has high precision and the prediction curve of the sound absorption coefficient was very similar to the experiments. The advantages of this method are simple, needing less trained samples, rapid and accurate.

The Semi-Empirical and Empirical Models for Predicting Sound Absorption Coefficients for a Novel Porous Laminated Composite Material

2003 ◽  
Vol 9 (11) ◽  
pp. 1249-1263
Author(s):  
Tsung-Lung Yang ◽  
Rongshun Chen
Keyword(s):  
Composite Material ◽  
Absorption Coefficient ◽  
Empirical Model ◽  
Sound Absorption ◽  
Laminated Composite ◽  
Sound Absorption Coefficient ◽  
Numerical Predictions ◽  
Viscous Loss ◽  
Semi Empirical ◽  
Laminated Composite Material

Made of polymer, metal, and polymer fibers of low melting point, a porous laminated composite material (PLCM) exhibits very highly sound absorption coefficient over the frequency of 500-2000 Hz with a relatively thin structure. In this paper we present two models to predict sound absorption characteristics for a PLCM. Firstly, we derive a semi-empirical model in which the flow resistivity of the PLCM is a function of the fibrous surface area under the assumption that most energy loss is due to the viscous loss consumed in the fibrous surface of a PLCM. Secondly, we propose an empirical model to predict the characteristic impedance and the propagation constant, which then is employed to determine the sound absorption coefficient for a new PLCM. Numerical predictions have been performed and experiments have been conducted to validate the two proposed models.

scholarly journals KARAKTERSTIK SERAPAN SUARA KOMPOSIT POLYESTER BERPENGUAT SERAT TAPIS KELAPA

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
I Made Astika ◽  
I Gusti Komang Dwijana
Keyword(s):  
Absorption Coefficient ◽  
Fiber Length ◽  
Sound Absorption ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Unsaturated Polyester ◽  
Sound Absorption Coefficient ◽  
Fiber Volume ◽  
Absorption Frequency ◽  
Class D

The purpose of this study is to investigate of sound absorption of coconut filter fiber composites. The research material made with coconut filter fiber as reinforcement and matrix resin unsaturated polyester (UPRs) type Yukalac BQTN 157 with 1% hardener types MEKPO (Methyl Ethyl Ketone Peroxide) and fiber treatment by  0,5% KMnO4. Production methods is poltrusion and the variations of fiber volume fraction are 20, 25 and 30% and fiber length are 5, 10 and 15 mm. Testing of sound absorption frequency are 250, 500, 1000, 2000 and 4000 Hz. The results of research show that  the highest value of sound absorption coefficient is on  the composites with composition of 10 mm fiber length and 30% fiber volume fraction, that is 0.550828. The values are included in the class “Sound Absorption Coefficient Class D (Extremely absorbing)” with the range 0.40 – 0.60 based on ISO standard 11654:1997.

scholarly journals Flame-Retardant and Sound-Absorption Properties of Composites Based on Kapok Fiber

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2845 ◽  
Author(s):  
Lihua Lyu ◽  
Yuanyuan Tian ◽  
Jing Lu ◽  
Xiaoqing Xiong ◽  
Jing Guo
Keyword(s):  
Absorption Coefficient ◽  
Flame Retardant ◽  
Magnesium Hydroxide ◽  
Hot Pressing ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Pressing Method ◽  
Kapok Fiber ◽  
Properties Of Composites

In order to improve the utilization rate of kapok fiber, flame-retardant and sound-absorption composites were prepared by the hot pressing method with kapok fiber as the reinforced material, polyε-caprolactone as the matrix material, and magnesium hydroxide as the flame retardant. Then, the effects of hot pressing temperature, hot pressing time, density of composites, mass fraction of kapok fiber, thickness of composites, and air layer thickness on the sound-absorption properties of composites were analyzed, with the average sound absorption coefficient as the index. Under the optimal process parameters, the maximum sound absorption coefficient reached 0.830, the average sound absorption coefficient was 0.520, and the sound-absorption band was wide. Thus, the composites belonged to high-efficiency sound-absorbing material. The flame-retardant effect of magnesium hydroxide on the composites was investigated, and the limiting oxygen index could reach 31.5%. Finally, multifunctional composites based on kapok fiber with flame retardant properties, and sound-absorption properties were obtained.

Acoustic Absorption Performance Research of Coir Density Board

2012 ◽  
Vol 549 ◽  
pp. 589-592
Author(s):  
Jia Yao ◽  
Li Li Ma ◽  
Lu Wei ◽  
Li Wei Jiang ◽  
Ya Qin Li
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Optimization Design ◽  
Morphological Characteristics ◽  
Wave Impedance ◽  
Sound Absorption Coefficient ◽  
Coir Fiber ◽  
Tropical Fruit ◽  
Practical Applications ◽  
Absorption Performance

Coir fiber is one of the tropical fruit fibers, the effective use of coir is not comprehensive now and the phenomenon of resources waste still exists. Full study of the advantage characteristics of coir has important significance for the expansion of the application field of coir resources. This article determines the light porous characteristics of coir from the micro-morphological characteristics. Through the prediction model research of the sound absorption coefficient of the porous fiber materials, the optimization density and the optimization thickness ranges can be got for the coir density board, so as to guide the optimization design of the sound absorption performance of coir density board. The changing rule of the sound absorption coefficient of the coir density board has been got by adopting the wave impedance tube method and the sound absorption coefficients by adding 5cm air gap has also been researched. The results of the experiments confirm that coir density board can be used as a secondary noise absorption material; the practical applications of coir density board are as the lightweight wall, the car interior trim or seat filling materials and the shipping cabins materials, to reduce the corresponding environment noise.

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