Effects of compression on sound absorption of transversely isotropic fibrous materials at oblique incidence

Keshavarz, Reza; Ohadi, Abdolreza

doi:10.1016/j.apacoust.2012.09.005

Cited by 13 publications

(5 citation statements)

References 8 publications

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“…In noise reduction materials, sound absorption material is very common and effective, which is widely used in the noise control engineering. In recent years, the study of porous sound absorption materials has been carried out and abundant achievements have been made (Duan, Cui, Xu, & Liu, 2012;Fouladi, Mohd Nor, Ayub, & Ghassem, 2012;Keshavarz & Ohadi, 2013;Na, Agnhage, & Cho, 2012;Shoshani, 1991;Xiang, Wang, Liu, Zhao, & Xu, 2013;Yilmaz, Powell, Lee, & Michielsen, 2012). Shaoshi (1991) studied sound absorption properties by combinations of multi-layers of non-woven fabric and single layer of woven fabric.…”

Section: Introductionmentioning

confidence: 98%

“…Based on the Delany-Bazley model, a prediction model of kapok sound absorption was established. Keshavarz and Ohadi (2013) analyzed the transmitting mechanism of sound waves in porous fibers by Biot Theory, calculated the sound absorption coefficients by transition matrix, and finally explored the acoustic properties of compressed porous fibers by oblique incidence. Na et al (2012) found that sound absorption properties of nanofibers had an advantage over common fibers.…”

Section: Introductionmentioning

confidence: 99%

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Sound absorption properties of composite structure with activated carbon fiber felts

Shen

Jiang

2014

The Journal of The Textile Institute

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This paper is intended to study the influence of different factors on the sound absorption properties of composite structure with activated carbon fiber felts. Activated carbon fiber felts made from viscose fiber mats were prepared and later combined with perforated panels to form four different composite sound absorption structures. Based on the transfer function method, the impedance tube was used to test the sound absorption coefficients of composite structure in an acoustic range of 80-6300 Hz frequencies. Analysis was made to discuss the influence of such factors on the sound absorption properties as the position of activated carbon fiber felts, thickness, and air space. The results demonstrated that the composite structure displayed different sound absorption properties at different frequencies.Perforated panels played the dominant role in sound absorption by the occurrence of resonance at 80-3500 Hz frequencies, while porous materials contributed the most at 3500-6300 Hz frequencies. At 80-3500 Hz frequencies, the best performance could be observed in the third type of composite structure with changes in the position of activated carbon fiber; the first resonance frequency of the first type of composite structure and perforated panel structure was basically the same, and that of the remaining three types significantly shifted towards the low frequencies with the same scale. In smaller thickness range, with the increase in the thickness of activated carbon fiber felts, sound absorption coefficients of the first and second types of composite structure increased, the first resonance frequency of the first type showing no apparent shift towards the low frequencies compared with what was shown in the second type; but when the thickness arrived at 15.6 mm, sound absorption properties of the composite structure had similar traits to that performed by porous materials in an acoustic range of 80-6300 Hz frequencies. With the increase in the distance of air space, sound absorption properties were improving at 80-650 Hz frequencies but decreasing at 650-3500 Hz frequencies, the first resonance frequency moving towards the low frequencies. At 3500-6300 Hz frequencies, as the position of activated carbon fiber felts and the distance of air space varied, sound absorption coefficients were basically unchanged; while as thickness increased, sound absorption coefficients improved.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Sound absorption properties of composite structure with activated carbon fiber felts

Shen

Jiang

2014

The Journal of The Textile Institute

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“…Fiber-based composites are widely used in buildings and constructions due to their good mechanical and acoustic insulation properties. Researchers found certain factors that affect the SAC of FRCs, i.e., fiber diameter, fiber type, fiber content, frequency, alkali treatment, sample thickness, fiber length, fiber orientation, and addition of plasticizer and/or fire-retardant finish [88][89][90][91][92][93]. Results reported by various researchers reveal that by increasing the content, frequency, sample thickness, and fiber inclination of fibers, the SAC of their composites will also be increased.…”

Section: Discussionmentioning

confidence: 99%

Section: Effect Of Compressionmentioning

confidence: 96%

“…The results indicated that increases in compression lead to decreases in the sound absorption coefficient in the low and medium frequency region for samples with thickness of 2 cm. For high frequencies, compression improves the absorption coefficient, as shown in Figure 37 [90]. Keshavarz et al described that the compression of materials may cause an increase or decrease in the sound absorption coefficient, which mainly depends on the method o compression.…”

Section: Effect Of Compressionmentioning

confidence: 99%

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Factors Affecting Acoustic Properties of Natural-Fiber-Based Materials and Composites: A Review

et al. 2021

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Recently, very rapid growth has been observed in the innovations and use of natural-fiber-based materials and composites for acoustic applications due to their environmentally friendly nature, low cost, and good acoustic absorption capability. However, there are still challenges for researchers to improve the mechanical and acoustic properties of natural fiber composites. In contrast, synthetic fiber-based composites have good mechanical properties and can be used in a wide range of structural and automotive applications. This review aims to provide a short overview of the different factors that affect the acoustic properties of natural-fiber-based materials and composites. The various factors that influence acoustic performance are fiber type, fineness, length, orientation, density, volume fraction in the composite, thickness, level of compression, and design. The details of various factors affecting the acoustic behavior of the fiber-based composites are described. Natural-fiber-based composites exhibit relatively good sound absorption capability due to their porous structure. Surface modification by alkali treatment can enhance the sound absorption performance. These materials can be used in buildings and interiors for efficient sound insulation.

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Effects of Silicone Surfactant on the Properties of Open‐Cell Flexible Polyurethane Foams

et al. 2016

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In this paper, the effects of silicone surfactant on the mechanical, thermal, and acoustical properties of flexible polyurethane foams are studied. At first, by introducing the reactions of the foam production and expressing the stoichiometric relationships, a method is provided to select the amounts of the basic compounds for getting the desirable properties. By knowing the OH number of polyol and the NCO content of isocyanate after selecting an amount of a blowing agent for the reaction, the quantity of each compound to produce the desirable foam can be found. Then different foams with various amounts of surfactant are produced. By preparing proper samples, the mechanical, thermal, nonacoustical, and acoustical properties of the foams are measured or calculated by using different instruments. The nonacoustical properties are obtained based on two distinct methods, i.e., a semiphenomenological method and an indirect method. The obtained properties are validated by comparing the calculated theoretical sound absorption coefficients with the measured ones. The results show that with a small increase of surfactant, the acoustical properties of foam samples improve by about 50% without any significant changes in other mechanical and thermal properties of the foams. This improvement results from the variations of reticulation rate and cell size. In addition, the initial desirable porosity and density considered in the stoichiometric relations are fairly achieved in produced samples. These results validate the accuracy of the stoichiometric relations.

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Effects of compression on sound absorption of transversely isotropic fibrous materials at oblique incidence

Cited by 13 publications

References 8 publications

Sound absorption properties of composite structure with activated carbon fiber felts

Sound absorption properties of composite structure with activated carbon fiber felts

Factors Affecting Acoustic Properties of Natural-Fiber-Based Materials and Composites: A Review

Effects of Silicone Surfactant on the Properties of Open‐Cell Flexible Polyurethane Foams

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