Effect of Thickness, Density and Cavity Depth on the Sound Absorption Properties of Wool Boards

Qui, H.-H.; Yang, En-Hui

doi:10.1515/aut-2017-0020

Cited by 41 publications

(23 citation statements)

References 7 publications

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“…In the frequency range from 108 to 4091 Hz, the sound absorption coefficient of the WNM increased with the increase of the area density. As mentioned earlier, the area density of the WNM refers to the number of fibres in a certain area, and higher area density indicates the presence of higher proportion of fibres in a specific area, which induces more resistance to the sound wave [ 26 , 45 ] and contributes to the higher sound absorption tendency [ 46 , 47 , 48 ]. As shown in Figure 8 c, the WNM with an area density of 790 GSM showed the highest NRC (0.43), significantly different ( p < 0.05) from the other WNM and the commercial materials (PET and CEL/PET).…”

Section: Resultsmentioning

confidence: 99%

Sustainable Lightweight Insulation Materials from Textile-Based Waste for the Automobile Industry

et al. 2021

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Globally, automotive manufacturers are looking for ways to produce environmentally sustainable and recyclable materials for automobiles to meet new regulations and customer desires. To enable the needs for rapid response, this study investigated the feasibility of using waste and virgin wool fibres as cost-effective and sustainable alternatives for automotive sound and heat insulation using a chemical-free approach. Several properties of the currently available commercial automotive insulators were investigated in order to facilitate the designing of green wool-based needle-punched nonwoven materials. The effect of fibre diameter, nonwoven surface, layer structure, thickness, and area density on sound absorption and thermal resistance was investigated. The results suggested that the wool nonwoven materials, fabricated using waste and virgin wool fibres, possessed extremely efficient acoustic and thermal insulating properties comparable with the currently used commercial synthetic insulating materials. Besides, the wool nonwoven materials showed identical antibacterial and antifungal properties with a greater biodegradation rate (50%) than that of the commercial synthetic insulating materials. Hence, this study showed that natural wool fibres have the potential to be used as green, lightweight, and sustainable materials in the automobiles, while they qualify for Reuse–Recycle and Reuse–Recover purposes at the end-of-life of vehicles.

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Section: Resultsmentioning

confidence: 99%

Sustainable Lightweight Insulation Materials from Textile-Based Waste for the Automobile Industry

et al. 2021

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“…The porosity of the material is also an important factor, and the convexity promotes increased porosity. A detailed presentation of the influence of individual factors on the obtained effect of sound absorption requires model considerations, which, in the case of fiber-based materials, and especially natural waste fibers with wide variation in thinness and length, and the sophisticated profiling of the composite plate, is an extremely complex issue [38,45,46]. It is known that resonant inclusions embedded in the soft matrix are conducive to the effective conversion of long longitudinal sound waves into short shear waves, which are subsequently absorbed.…”

Section: Compositesmentioning

confidence: 99%

Green Sound-Absorbing Composite Materials of Various Structure and Profiling

et al. 2021

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This article presents thermoplastic sound-absorbing composites manufactured on the basis of renewable raw materials. Both the reinforcing material and the matrix material were biodegradable and used in the form of fibers. In order to mix flax fibers with polylactide fibers, the fleece was fabricated with a mechanical system and then needle-punched. The sound absorption of composites obtained from a multilayer structure of nonwovens pressed at different conditions was investigated. The sound absorption coefficient in the frequency ranging from 500 Hz to 6400 Hz was determined using a Kundt tube. The tests were performed for flat composites with various structures, profiled composites, and composite/pre-pressed nonwoven systems. Profiling the composite plate by convexity/concavity has a positive effect on its sound absorption. It is also important to arrange the plate with the appropriate structure for the incident sound wave. For the composite layer with an added pre-pressed nonwoven layer, a greater increase in sound absorption occurs for the system when a rigid composite layer is located on the side of the incident sound wave. The addition of successive nonwoven layers not only increases the absorption but also extends the maximum absorption range from the highest frequencies towards the lower frequencies.

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“…Noise pollution is considered one of the four major environmental hazards that include air, water and solid waste pollution. Sound absorbing materials therefore play an important role in mitigating noise pollution effects on human health such as hearing loss and stress [96]. Low frequency noise, particularly that with a frequency range of 10 Hz to 100 Hz poses a special environmental noise that can cause heightened distress in people that are sensitive to its effects [97].…”

Section: Sound Absorptionmentioning

confidence: 99%

Engineering Characteristics and Potential Increased Utilisation of Sawdust Composites in Construction—A Review

Mwango¹,

Kambole²

2019

JBCPR

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Many timber producing countries generate more than 2 million m 3 of sawdust annually. In developing countries, sawdust is often disposed of by open dumping, open burning, or dumping in landfills. This poses huge environmental challenges related to air pollution, greenhouse gas emissions, and destruction of plant and aquatic life. Findings from this review article reveal that sawdust can be used to make sawdust construction composites with good modulus of elasticity, water absorption and strength characteristics that satisfy international specifications. These composites include particleboards, sawdust concrete blocks or bricks and sawdust concrete. The article concludes that partially replacing 5% to 17% of sand with sawdust, or replacing cement with sawdust ash in proportions of 5% to 15% in concrete mixes can produce structural concrete with compressive strengths greater than 20 MPa. Partially replacing 10% to 30% of sand used in the manufacture blocks and bricks with sawdust can also produce sawdust bricks and blocks with compressive strengths greater than 3 MPa. Sawdust composites are also attractive for their low thermal conductivity, high sound absorption and good sound insulation characteristics. These findings indicate that increased utilisation of sawdust composites in construction will mitigate against potential sawdust environmental pollution, conserve energy and reduce disposal costs.

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Effect of Thickness, Density and Cavity Depth on the Sound Absorption Properties of Wool Boards

Cited by 41 publications

References 7 publications

Sustainable Lightweight Insulation Materials from Textile-Based Waste for the Automobile Industry

Sustainable Lightweight Insulation Materials from Textile-Based Waste for the Automobile Industry

Green Sound-Absorbing Composite Materials of Various Structure and Profiling

Engineering Characteristics and Potential Increased Utilisation of Sawdust Composites in Construction—A Review

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