“…Here, i and j are the nodal diameters and circles of the modes, whereas λ 2 ij are the modal constants. For example, the modal constants are 10.22 and 39.77 for the modes (0,1) and (0,2), respectively, for a clamped circle sample (Dragonetti et al 2020). The critical frequency of a sample can be determined using (Norton and Karczub 2003):…”
Section: Prediction Of Sound Transmission Losses (Stls)mentioning
Although some studies have been conducted to show how natural fibers can replace synthetic materials, the use of many natural fibers is still limited. On the other hand, the use of natural fibers can become very common in many applications once their performance is fully understood. This paper aims to present a critical assessment of the acoustic properties of natural fiber samples. First, the methods commonly used for the measurement and prediction of the acoustic properties of natural fiber samples are determined. Second, the common techniques for measuring sound absorption coefficients (SACs) and sound transmission losses (STLs) are presented, and their advantages and limitations are evaluated. After that, the models commonly used for the prediction of acoustic properties are presented. Then, the SACs of many natural fiber samples are presented along with the thickness, bulk density and flow resistivity of the samples. Furthermore, the SACs of the samples are normalized using sample thickness and bulk density, and the sound absorption performance of the fiber samples is evaluated. Based on the results of many natural fiber samples, an empirical model for estimating the SACs of natural fiber samples is presented. Finally, the STLs of some porous natural fiber samples are presented.
“…Here, i and j are the nodal diameters and circles of the modes, whereas λ 2 ij are the modal constants. For example, the modal constants are 10.22 and 39.77 for the modes (0,1) and (0,2), respectively, for a clamped circle sample (Dragonetti et al 2020). The critical frequency of a sample can be determined using (Norton and Karczub 2003):…”
Section: Prediction Of Sound Transmission Losses (Stls)mentioning
Although some studies have been conducted to show how natural fibers can replace synthetic materials, the use of many natural fibers is still limited. On the other hand, the use of natural fibers can become very common in many applications once their performance is fully understood. This paper aims to present a critical assessment of the acoustic properties of natural fiber samples. First, the methods commonly used for the measurement and prediction of the acoustic properties of natural fiber samples are determined. Second, the common techniques for measuring sound absorption coefficients (SACs) and sound transmission losses (STLs) are presented, and their advantages and limitations are evaluated. After that, the models commonly used for the prediction of acoustic properties are presented. Then, the SACs of many natural fiber samples are presented along with the thickness, bulk density and flow resistivity of the samples. Furthermore, the SACs of the samples are normalized using sample thickness and bulk density, and the sound absorption performance of the fiber samples is evaluated. Based on the results of many natural fiber samples, an empirical model for estimating the SACs of natural fiber samples is presented. Finally, the STLs of some porous natural fiber samples are presented.
“…Mano [115] conducted a comprehensive study on the effects of natural hemp fibers on the compressive behavior of corrugated sandwich panels. Dragonetti et al [116] studied the sound transmission loss of green sandwich structures composed of hemp and bio-epoxy. Using the latest 3D-printing technology and fused deposition molding, Antony et al [117] continued their previous research [113] on the mechanical behavior of renewable honeycomb sandwich panels made of hemp fibers and PLA.Figure 8.The CATIA CAD software model and manufactured honeycomb sandwich structure [113].…”
Section: Sandwich Structures Made Of Non-wood Cellulose Natural Fibersmentioning
In recent years, concerns about environmental pollution have led to the development of natural fiber sandwich structures as alternatives to petroleum-based ones. This paper reviews various studies on sandwich structures composed of non-wood cellulose-nature fibers. These fibers mainly include flax, hemp, jute, kenaf, sisal, coir, and bamboo. The studies are classified based on the type of fibers, the components in which they are used, and experimental tests/numerical investigations. Furthermore, a few suggestions for future research in the field of eco-friendly sandwich structures are made.
“…Sound transmission loss (STL) helps to determine the amount of noise reduction that is achieved by an object, material or construction assembly as sound travels through it. Thus, it is very important to characterize the sound isolation property of homogeneous materials and composite structures (Dragonetti et al, 2020).…”
Section: Sound Transmission Loss Behaviour Of Compositesmentioning
In a developing and increasing world, the increment in the consumption of natural resources brings environmental problems together. The use of plant raw materials has great importance in the construction industry, which has a high consumption rate. Increasing demand to develop sustainable and environmentally friendly materials has increased the use of natural fibers in sustainable building materials (sound absorption, heat and sound insulation). The fact that hemp fiber does not have high water consumption in the production, can be grown without the need for fertilizers and pesticides, as well as leaving a rich soil structure for the next crop by destroying weeds ensures the protection of the soil and the environment. From this point of view, in this study sound insulation properties of hemp fiber reinforced composites were investigated. Polypropylene fiber was used as a matrix material. To compare the performance of hemp fiber, cotton fiber was also utilized and different constructions were produced from these materials. The composites were produced by the hot-press method. It was found that the composites made of hemp fiber showed significantly higher sound insulation than the cotton fiber reinforced composites and can be used as a sound isolation material at specific high frequencies.
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