scholarly journals Investigation of the Sound Absorption and Transmission Loss Performances of Green Homogenous and Hybrid Luffa and Jute Fiber Samples

2021 ◽  
Author(s):  
Ahmet C. Ozcan ◽  
Kenan Y. Sanliturk ◽  
Garip Genc ◽  
Hasan Koruk
Keyword(s):  
High Frequency ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Natural Fibers ◽  
Acoustic Properties ◽  
Jute Fiber ◽  
Transmission Losses ◽  
Hybrid Fiber ◽  
Practical Applications ◽  
Impedance Tube Method

In order to promote the use of natural fibers in noise and vibration applications, the properties of these structures should be fully identified. The sound absorption coefficients (SACs) and transmission losses (TLs) of green luffa fiber samples are thoroughly investigated and their acoustic performances are compared with the acoustic performances of green homogenous jute and hybrid jute/luffa fiber samples in this study. For this purpose, green homogenous luffa and jute fiber samples and their green hybrid fiber samples with different thicknesses (10, 20, 30, and 40 mm) are produced and their SACs and TLs are determined using the impedance tube method. First, the methods for the experimental identification of acoustic properties are presented and the variations in the measured acoustic properties are identified. After that, the effects of sample thickness on the acoustic performances of homogenous luffa as well as jute samples and their hybrid fiber samples as a function of frequency are explored. The thickness-dependent tendencies of the SACs and TLs of homogenous and hybrid luffa and jute fiber samples for low, medium and high frequency ranges are determined. Then, the acoustic performances of the homogenous and hybrid luffa and jute samples are compared and evaluated. The results and analyses for the acoustic properties of homogeneous luffa and jute fiber samples and their hybrid fiber samples for a variety of thicknesses and different frequencies presented here can be used to design homogenous as well as hybrid luffa and jute fiber structures in practical applications.

scholarly journals Identification of uncertainty levels of acoustic properties of biocomposites under different mounting conditions in impedance tube tests

2021 ◽  
Vol 69 (5) ◽  
pp. 392-400
Author(s):  
Hasan Koruk ◽  
Yusuf Saygili ◽  
Garip Genc ◽  
Kenan Y. Sanliturk
Keyword(s):  
Sound Absorption ◽  
Transmission Loss ◽  
Acoustic Properties ◽  
Petroleum Jelly ◽  
Impedance Tube ◽  
Hard Materials ◽  
Inner Diameter ◽  
Acoustic Properties Of Materials ◽  
Impedance Tube Method ◽  
Textured Materials

Impedance tube method is widely used to measure acoustic properties of materials. Although this method yields reliable acoustic properties for soft textured materials, uncertainty levels of measured acoustic properties for hard materials, including biocomposites, can be quite large, mainly due to uncertain mounting conditions. Here, the effects of mounting conditions on the acoustic properties of biocomposites in an impedance tube are investigated. First, nominally identical biocomposite samples with a diameter equal to the inner diameter of impedance tube are manufactured and their acoustic properties are determined. As hard materials practically cause fitting problems in the impedance tube, the diameters of samples are reduced, as in practice, by small amounts and acoustic properties of modified samples are determined. Furthermore, in order to match the diameters of samples to the inner diameter of impedance tube, different materials such as tape, petroleum jelly and cotton are applied around samples to close the air gap between the samples and the tube's inner wall. All the results are compared, and the uncertainty levels caused by different mounting conditions on the acoustic properties of biocomposites are identified. The results show that the transmission loss (TL) measurements are dramatically affected by the mounting conditions while the sound absorption conditions are less sensitive to the mounting conditions. The deviations in the measured TL levels are highest for the samples with tape and wax (10–15 dB). On the other hand, the deviations in the measured sound absorption coefficients are highest for the samples with cotton and tape (1–2%).

scholarly journals Ultralight Graphene Oxide/Polyvinyl Alcohol aerogel for broadband and tuneable acoustic properties

2021 ◽  
Author(s):  
Mario Rapisarda ◽  
Gian-Piero Malfense Fierro ◽  
Michele Meo
Keyword(s):  
Graphene Oxide ◽  
Polyvinyl Alcohol ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Acoustic Properties ◽  
Low Density ◽  
Transmission Losses ◽  
New Class ◽  
Processing Times

Abstract An ultralight Graphene Oxide/Polyvinyl Alcohol (GO/PVA) aerogel is proposed as a new class of acoustic materials with tuneable and broadband sound absorption and transmission loss. The interaction between GO sheets and PVA molecules are exploited in our environmentally friendly manufacturing process to fabricate aerogels with hierarchical and tuneable porosity embedded in a honeycomb scaffolding. The developed aerogels show an enhanced dissipation of sound energy, with an extremely low density of 2.10 kg m-3 , one of the lowest values ever reported for acoustic materials. We have first experimentally evaluated and optimized the effects of composition and thickness on the acoustic properties, namely sound absorption and sound transmission losses. Subsequently, we have employed a semi-analytical approach to evaluate the effect of different processing times and find the relationships between the acoustic and non-acoustic properties of the materials. Over the 400 – 2500 Hz range, the reported average sound absorption coefficients are as high as 0.79 for low density aerogels, while the average sound transmission losses can reach 15.8 dB for higher density aerogels. We envision our subwavelength aerogel-based design, tailored at achieving optimal acoustic performance, as a novel lightweight material for advanced engineering applications.

Investigation of the acoustic properties of needle punched nonwoven produced of blend with sustainable fibers

2018 ◽  
Vol 30 (3) ◽  
pp. 444-458 ◽  
Author(s):  
Shariful Islam ◽  
Shaikh Md. Mominul Alam
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Natural Fibers ◽  
Sound Transmission ◽  
Textile Composites ◽  
Acoustic Properties ◽  
Textile Composite ◽  
Content Type ◽  
Hemp Fibers

Purpose The purpose of this paper is to investigate the acoustic properties of needle-punched nonwovens produced of bamboo, banana and hemp fibers blended with polyester (PET) and polypropylene (PP) as they are supportive enough to minimize sound transmission inside the automobiles. Design/methodology/approach Textile materials like bamboo, banana and hemp blended with PET and PP in the ratio of 35:35:30 were applied to make the web. The needle-punching technique was applied to each web for three times to form a full nonwoven textile composite. The concept of PET/PP blend with natural fibers was to enhance the consistency and thermoform propensity of the composites. When nonwoven textile composites were placed in between a sound source and a receiver, they absorbed annoying sound by dissolving sound wave energy. Sound absorption coefficient was measured by the impedance tube method as per ASTM C384 Standard. Bamboo/PET/PP composite showed the highest absorption coefficient in most of the frequencies. Findings Physical and comfort properties were tested for the composites and it was noticed that bamboo/PET/PP composites with its compressed structure showed a better stiffness value, lesser thermal conductivity, lesser air permeability, better absorption coefficient and highest sound transmission loss compared to other two composites. At 840 Hz, the absorption coefficient of bamboo/PET/PP remained in satisfactory level but it was inferior by 20 percent in banana/PET/PP. Conversely at more frequencies like 1,680 Hz, there was a decrease from the target level in all the nonwovens composites, which could be enhanced by raising the thickness of the nonwovens, and all these properties of bamboo/PET/PP were considered appropriate for controlling noise inside the vehicles. Practical implications This research will provide facilities to decrease noise inside the vehicles. It will improve the apparent value of the automobiles to the traveler and also provide a sensible goodwill to the manufacturer. Originality/value This research will open several ways for the development of different nonwoven composites, particularly for the sound absorption and will open possible ways for the scholars to further study in this field.

scholarly journals The Effects of Various Additive Components on the Sound Absorption Performances of Polyurethane Foams

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Shuming Chen ◽  
Yang Jiang ◽  
Jing Chen ◽  
Dengfeng Wang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Polyurethane Foams ◽  
Acoustic Properties ◽  
Acoustic Absorption ◽  
Absorption Properties ◽  
Maximum Enhancement ◽  
Flexible Polyurethane ◽  
Pu Foams

Flexible polyurethane (PU) foams comprising various additive components were synthesized to improve their acoustic performances. The purpose of this study was to investigate the effects of various additive components of the PU foams on the resultant sound absorption, which was characterized by the impedance tube technique to obtain the incident sound absorption coefficient and transmission loss. The maximum enhancement in the acoustic properties of the foams was obtained by adding fluorine-dichloroethane (141b) and triethanolamine. The results showed that the acoustic absorption properties of the PU foams were improved by adding 141b and triethanolamine and depended on the amount of the water, 141b, and triethanolamine.

Car's Materials Acoustic Properties Test and Analysis

2013 ◽  
Vol 785-786 ◽  
pp. 1244-1247
Author(s):  
Yan Liu ◽  
Xiao Juan Zhang ◽  
Zong Cai Liu
Keyword(s):  
Noise Reduction ◽  
High Frequency ◽  
Sound Absorption ◽  
Transmission System ◽  
Acoustic Properties ◽  
Frequency Noise ◽  
Car Industry ◽  
High Frequency Noise ◽  
Urban Construction ◽  
The Impact

With the development of the car industry, the pace of the urban construction is accelerating as well. Cars have gradually entered the ordinary family. As the car noise has a big effect on the health of the passengers, as well as on the surroundings, one of the car industry key duties is the car noise reduction. By researching the materials applied to car, this article describe that PU material could reduce the impact of the engine noise on the cab efficiently; Polypropylene needle-spun felt could reduce the noise passed by chassis; PET material's sound absorption is poor in mid bass, however in high frequency it's sound absorption is good; sound absorbing sponge can reduce the low and high frequency noise; The combine sponge can reduce the noise from the tire and transmission system ; Cotton material could absorb the high frequency noise.

scholarly journals Acoustic Properties of Mixing Empty Fruit Bunch and Oil Palm Frond Natural Fibres

2019 ◽  
Vol 8 (4) ◽  
pp. 6347-6349
Keyword(s):  
Oil Palm ◽  
Sound Absorption ◽  
Natural Fibre ◽  
Natural Fibres ◽  
Acoustic Properties ◽  
Empty Fruit Bunch ◽  
Frequency Range ◽  
Oil Palm Frond ◽  
Impedance Tube Method ◽  
Palm Frond

Natural fibre is being studied and used as sound absorber for its promising acoustic properties. For instance, Germany have commercial plants that are producing sound absorbers from natural fibre. Natural fibre is eco-friendly and has no effect on human health. Besides that, the production cost of natural fibre is cheaper than synthetic fibre. This research reported the thickness effects on acoustic properties in different ratios of natural fibres of empty fruit bunch (EFB) and oil palm frond (OPF). Four different thickness of low density fibre board (LDF) have been fabricated (12 mm, 14 mm, 16 mm and 18 mm) in density of 120 kg/m3 . The Sound Absorption Coefficient (SAC) was tested by using the Impedance Tube Method (ITM) according to ASTM E1050-98 standards at frequency from 0 Hz to 6400 Hz. The results show the values of SAC for all samples increase with increasing in thickness from frequency range of 0 Hz – 4500 Hz. It is noteworthy that the LDF with thickness of 16 mm and 18 mm can be classified as Class A sound absorbing material according to sound absorption classes and possess the SAC values of 0.8 and above at a wider frequency range, which is 2500 Hz to 6400 Hz. The combination of EFP and OPF natural fibres has a very promising and excellent performance in acoustic properties.

scholarly journals Sound absorbing and insulating properties of natural fiber hybrid composites using sugarcane bagasse and bamboo charcoal

2021 ◽  
Vol 16 ◽  
pp. 155892502110448
Author(s):  
Santhanam Sakthivel ◽  
Selvaraj Senthil Kumar ◽  
Eshetu Solomon ◽  
Gedamnesh Getahun ◽  
Yohaness Admassu ◽  
...  
Keyword(s):  
Composite Materials ◽  
Physical Properties ◽  
Sugarcane Bagasse ◽  
Sound Absorption ◽  
Natural Fiber ◽  
Natural Fibers ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Bamboo Charcoal ◽  
Green Composite

This research paper reports a study on thermal and sound insulation samples developed from sugarcane bagasse and bamboo charcoal for automotive industry applications. The sugarcane bagasse and bamboo charcoal fiber is a potential source of raw material that can be considered for thermal and sound insulation applications. Natural fibers are commonly used in diverse applications and one of the most important applications is sound absorption. Natural fiber hybrid composite currently is in greater demand in industries because of their advantages such as low cost, biodegradability, acceptable physical properties, and so on. Eco-friendly sound-absorbing composite materials have been developed using bamboo charcoal and sugarcane bagasse fibers. From these fibers five types of natural fiber green composite were developed using the compression bonding technique. The natural composite noise control performance contributes to its wider adoption as sound absorbers. The sound absorption coefficient was measured according to ASTM E 1050 by the Impedance tube method. The physical properties of natural fiber composites such as thickness, density, porosity, air permeability, and thermal conductivity were analyzed for all samples in accordance with ASTM Standard. The result exposed that natural fiber green composite were absorbing the sound resistance of more than 70% and the natural fibers composites provide the best acoustic absorption properties, these composite materials have adequate moisture resistance at high humidity conditions without affecting the insulation and acoustic properties.

scholarly journals Acoustic Properties of 316L Stainless Steel Hollow Sphere Composites Fabricated by Pressure Casting

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1047
Author(s):  
Chunhe Wang ◽  
Fengchun Jiang ◽  
Shuaiqi Shao ◽  
Tianmiao Yu ◽  
Chunhuan Guo
Keyword(s):  
Absorption Coefficient ◽  
Hollow Sphere ◽  
Sound Absorption ◽  
Random Distribution ◽  
Transmission Loss ◽  
Acoustic Properties ◽  
Sound Absorption Coefficient ◽  
Pressure Casting ◽  
Sound Transmission Loss ◽  
At Resonance

In this study, we prepared metal hollow sphere composites (MHSCs) using metal hollow spheres (MHSs) by pressure casting under vacuum conditions, and investigated the acoustic properties. The density of the MHSCs was measured using the mass to volume ratio, the microstructure of the MHSCs was observed using a scanning electron microscope, and the acoustic properties of the MHSCs were tested using an impedance tube. The measured MHSCs showed that the densities of the MHSCs with the random distribution of MHSs with diameter ~3.28 mm (1.74 g/cm3 to 1.77 g/cm3) (MHSC-3.28) were nearly equal to that of the MHSCs with the random distribution of MHSs with diameter ~5.76 mm (1.74 g/cm3 to 1.76 g/cm3) (MHSC-5.76), and lower than that of the MHSCs with the layered structure of MHSs with diameter ~3.28 mm (1.93 g/cm3 to 1.97 g/cm3) (MHSC-LS). Microstructural observations confirmed that the interface region between the MHSs and matrix demonstrated a simple physical combination pattern with pores. The acoustic properties of the MHSCs showed that the sound absorption coefficient of MHSC-LS was lower than that of MHSC-3.28 and higher than that of MHSC-5.76 at off-resonance. The sound absorption coefficient peak value of MHSC-3.28 was higher than that of MHSC-LS, and lower than that of MHSC-5.76 at resonance. The sound transmission loss of MHSC-3.28 was lower than that of MHSC-5.76, which shows the rules are independent from the resonance. The sound transmission loss of MHSC-LS was higher than that of MHSC-5.76 at resonance, but lower than that of MHSC-3.28 at off-resonance. In addition, we discuss the propagation mechanism of the sound waves in the MHSC, which is mainly determined by the distribution of the MHSs in the MHSC.

Comparative Study of Sound Absorption Coefficients of Coir/Kenaf/Sugarcane Bagasse Fiber Reinforced Epoxy Composites

2017 ◽  
Vol 730 ◽  
pp. 48-53 ◽  
Author(s):  
Elammaran Jayamani ◽  
Soon Kok Heng ◽  
Muhammad Khusairy bin Bakri ◽  
Sinin Hamdan
Keyword(s):  
Absorption Coefficient ◽  
Sugarcane Bagasse ◽  
Sound Absorption ◽  
Transfer Functions ◽  
Natural Fibers ◽  
Epoxy Composites ◽  
Sound Absorption Coefficient ◽  
Coconut Coir ◽  
Impedance Tube Method ◽  
Bagasse Fiber

This research focuses on the sound absorption coefficient of three different natural fibers reinforced epoxy composites. The natural fibers used are coconut coir, kenaf, and sugarcane bagasse. All of these fibers were mixed with epoxy resin and hardener with a ratio of 4:1. The mixtures were then poured into a circular mold and compressed by using compression molding technique. It was left for curing for 24 hours at standard room temperature. The results were obtained using the two-microphone transfer functions impedance tube method according to ASTM E1050-12. It is found that as the fiber loading increased, the sound absorption coefficient of the composites increased. 20wt% Coconut coir epoxy composites and 20wt% kenaf fiber epoxy composites have the highest sound absorption coefficient with almost similar sound absorption of 0.078 at 5000Hz. While, 20wt% sugarcane bagasse epoxy composites have sound absorption of 0.075 at 5000Hz.

scholarly journals Ultralight graphene oxide/polyvinyl alcohol aerogel for broadband and tuneable acoustic properties

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mario Rapisarda ◽  
Gian-Piero Malfense Fierro ◽  
Michele Meo
Keyword(s):  
Graphene Oxide ◽  
Polyvinyl Alcohol ◽  
Sound Absorption ◽  
Sound Transmission ◽  
Acoustic Properties ◽  
Transmission Losses ◽  
Emi Shielding ◽  
New Class ◽  
Processing Times ◽  
Broadband Sound

AbstractAn ultralight graphene oxide (GO)/polyvinyl alcohol (PVA) aerogel (GPA) is proposed as a new class of acoustic materials with tuneable and broadband sound absorption and sound transmission losses. The interaction between GO sheets and PVA molecules is exploited in our environmentally friendly manufacturing process to fabricate aerogels with hierarchical and tuneable porosity embedded in a honeycomb scaffold. The aerogels possess an enhanced ability to dissipate sound energy, with an extremely low density of 2.10 kg m−3, one of the lowest values ever reported for acoustic materials. We have first experimentally evaluated and optimised the effects of composition and thickness on the acoustic properties, namely sound absorption and sound transmission losses. Subsequently, we have employed a semi-analytical approach to evaluate the effect of different processing times on acoustic properties and assessed the relationships between the acoustic and non-acoustic properties of the materials. Over the 400–2500 Hz range, the reported average sound absorption coefficients are as high as 0.79, while the average sound transmission losses can reach 15.8 dB. We envisage that our subwavelength thin and light aerogel-based materials will possess other functional properties such as fire resistance and EMI shielding, and will prove to be novel acoustic materials for advanced engineering applications.

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