Effects of compression on the sound absorption of porous materials with an elastic frame

Wang, Chao‐Nan; Kuo, Yan-Min; Chen, Shih-Kai

doi:10.1016/j.apacoust.2006.08.006

Cited by 36 publications

(23 citation statements)

References 10 publications

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“…3. This differences due to porous material compressing which appear clearly at all frequencies range (Lee and Chen 2001), (Wang et al, 2008). Drop of AAC at frequency 1765-2725 Hz with value 0.67 indicated is poor in mid frequency.…”

Section: Discussionmentioning

confidence: 88%

Acoustic Properties of Innovative Material from Date Palm Fibre

ALRahman

Raja²,

Rahman³

et al. 2012

American Journal of Applied Sciences

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Problem statement: An organic material is one of the major requirements to improve living environment and the invention of materials need to consider for the best solution. This study presents an experimental investigation on pure porous from Date Palm Fibre (DPF). The effectiveness of sound absorbers depends on structural architecture of this material. This study was conducted to examine the potential of using date palm fibre as sound absorber. The effects of porous layer thicknesses, densities and compression on Acoustic Absorption Coefficient (AAC) of sound absorber using date palm fibre were studied. Approach: Rigid frame Johnson-Allard Model for various sample thicknesses was used in this study. The measurements were conducted in impedance tube on normal incidence acoustic absorption. The date palm fibre was mixed with latex which used for physical treatment on this material. Acoustic absorption behaviour of a porous material with different thicknesses was studied as well as samples with same thickness but different densities. In addition, samples with same properties but different period of compression time were inspected. The tests were in accordance to ISO 10534-2 and ASTM E1050-98 international standards for Acoustic Absorption Coefficient (AAC). Results: The experimental data indicates that two peak values of AAC is 0.93 at 1356Hz for sample with 50 mm thickness, also the AAC at high frequency for same thickness is 0.99 at 4200-4353 Hz that means able to improve acoustic absorption coefficient at low and high frequencies with significant increasing. Meanwhile, another experimental results were acquired for AAC of date palm fibre, with samples thicknesses of 35 mm at different densities .The results show that denser sample (11 Kg m −3 ) has higher AAC value of 0.83 at 1934-2250 Hz as compared to less dense sample (9.92 Kg m −3 ) with AAC value 0.84 at 2443-2587 Hz . Conclusion: Acoustic absorption coefficient AAC of date palm fibre was increased at all frequencies when the thickness of sample was increased, particularly at low frequencies less than 1200 Hz. The introduction of latex on the samples adds stiffness, so that sound can be dissipated significantly as it travels through material. Results from the experimental tests show that date palm fibre has good acoustic properties at low and high frequencies and can be used as an alternative replacement to conventional product. Increasing density of the samples, increase the AAC as well. The innovative acoustic absorption panel has a good potential because they are cheaper and lighter in comparison to asbestos and rock wool industrial materials.

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Section: Discussionmentioning

confidence: 88%

Acoustic Properties of Innovative Material from Date Palm Fibre

ALRahman

Raja²,

Rahman³

et al. 2012

American Journal of Applied Sciences

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“…In this research, it was sought that rigid frame condition could be considered for solid structure of coir fiber, as the flow resistivity of coir fiber found to be very low (less than 10,000 Nsm −4 ) (Wang et al, 2008). As a result, a rigid frame model was assumed to be applicable for analytical prediction of absorption characteristics of coir fiber.…”

Section: Rigid Frame Method: Johnson-allard Modelmentioning

confidence: 99%

“…Castegnede et al (2000) had shown that the variation in those parameters follow a simple law. The new porosity, tortuosity, flow resistivity, thermal characteristics length, Viscous Characteristics length caused by the 1D compression are defined as (Castegnede et al, 2000;Wang et al, 2008):…”

Section: Equation Of the Effective Densitymentioning

confidence: 99%

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Effect of Compression on the Acoustic Absorption of Coir Fiber

Nor¹

2010

American Journal of Applied Sciences

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Problem statement:The absorption characteristics of coir fiber were analyzed previously. Analytical method to predict the acoustical behavior of coir fiber has already been developed. However, compression effects of coir fiber were not explored which might significant for acoustics absorption during seat padding. In this study, compression effect on the sound absorption characteristics of coir fiber are demonstrated based on the previous analytical approach such as rigid frame method with the modification in the physical parameters. Approach: The verification of the estimated acoustical absorption coefficient in uncompressed condition using rigid frame JohnsonAllard Model are shown for three different thicknesses of industrially processed coir fiber mixed with binder latex. Measurements were conducted in impedance tube on normal incidence sound absorption of coir fiber. It is well known that the absorption behavior of a porous material varies during compression and affects the physical parameters. In these analyses, formulas proposed by Castagnede are employed to predict the compression effect on the absorption of coir fiber which takes into account the modifications of the physical parameters during compression. Results: The agreement between the analytical and measured results is justified for all three sample thicknesses in uncompressed condition. Analyses on the acoustic behavior of material during compressed condition show that compression has a substantial effect on the absorption of coir fiber. It also indicates that the absorption of coir fiber can be enhanced by compressing the material. In addition, the absorption performances are compared by varying the compression rate on material at uncompressed and compressed condition. Conclusion: From overall analyses, it is evident that compression of coir fiber can significantly change the absorption behavior of coir fiber from the actual acoustical characteristics as estimated at normal condition. Moreover, compressing the material might be considered as a possible approach to improve the absorption coefficient of coir fiber. An additional example is presented to show a potential way of enhancing absorption coefficient of coir fiber utilizing compression effect.

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“…As it been shape according to the size of the impedance tube, it will be fitted nicely into the impedance tube. The compression of the natural has a significant effect to sound absorption coefficient [7,14]. As the thickness fibre increase will provide more porous structure to the natural fibre sample.…”

Section: Compressed Fibrementioning

confidence: 99%

Effect of physical properties of natural fibre on the sound absorption coefficient

Zunaidi

Hong

Majid

et al. 2017

J. Phys.: Conf. Ser.

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The aim of the study was to analyse the effect of physical properties of natural fibre to the sound absorption coefficient. It was also aimed to study the relation of the physical properties of natural fibre to wider the frequency range and increase the sound absorption coefficient. There were two types of natural fibre will be studied such as kenaf fibre and rice straw fibre. The performance of sound absorption coefficient was measured using fabricated impedance tube according to ISO 10534-2. The physical properties of the natural fibre may affect the sound absorption coefficient either shifted to low frequency or shifted to high frequency range. All the physical properties that influence the sound absorption coefficient of natural fibre will be explained. The physical properties of natural fibre that will be studied were fibre thickness, fibre diameter and compressed fibre. Results have shown that the fibre thickness and diameter have a big effect to sound absorption coefficient. From the results, the utilization of the sound absorption coefficient can be achieved by choosing the suitable natural fibre according to its physical properties for a suitable application.

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Effects of compression on the sound absorption of porous materials with an elastic frame

Cited by 36 publications

References 10 publications

Acoustic Properties of Innovative Material from Date Palm Fibre

Acoustic Properties of Innovative Material from Date Palm Fibre

Effect of Compression on the Acoustic Absorption of Coir Fiber

Effect of physical properties of natural fibre on the sound absorption coefficient

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