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![(a) Cross-section morphology of the hemp fiber bundle [2] and (b) schematic version of the hemp fiber bundle.](publication/275068582/figure/fig5/AS:1088875497828356@1636619557614/a-Cross-section-morphology-of-the-hemp-fiber-bundle-2-and-b-schematic-version-of.jpg)
(a) Cross-section morphology of the hemp fiber bundle [2] and (b) schematic version of the hemp fiber bundle.
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![(a) Cross-section morphology of the hemp fiber bundle [2] and (b)...](publication/275068582/figure/fig1/AS:1088875497828353@1636619557435/a-Cross-section-morphology-of-the-hemp-fiber-bundle-2-and-b-schematic-version-of_Q320.jpg)
![(a) Cross-section morphology of the hemp fiber bundle [2] and (b)...](publication/275068582/figure/fig5/AS:1088875497828356@1636619557614/a-Cross-section-morphology-of-the-hemp-fiber-bundle-2-and-b-schematic-version-of_Q320.jpg)
Natural fiber bundle like hemp fiber bundle usually includes many small lumens embedded in solid region; thus, it can present lower thermal conduction than that of conventional fibers. In the paper, characteristic of anisotropic transverse thermal conductivity of unidirectional natural hemp fiber bundle was numerically studied to determine the depe...
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Citations
... Additionally, the transverse thermal conductivity was significantly influenced by the lumen structure rather than the structures and chemical components of the composites. Similar findings were obtained by Zheng [10] in a study investigating the thermal properties of hemp fibre bundles by focusing on their anisotropic thermal conductivities. Their analysis used a 2D computational composite model of unidirectional hemp fibre bundles in a hypothetical matrix in ABAQUS. ...
In industry, synthetic fibre reinforcements are popular due to their cost-effectiveness and lightweight nature. However, the non-reusability and non-degradability have raised environmental concerns and prompted scientists to explore more environmentally friendly alternatives. Natural fibres are being investigated as potential replacements to address these issues and promote sustainability. This study investigated the effect of fibre loading and orientation on the heat conductivity of polymer resins using a finite element-based numerical model developed in our previous research. The numerical analysis was conducted in ANSYS® modelling and simulation using glass and sisal fibres in combination with three distinct matrix materials (epoxy, polyester, and vinyl ester). Different orientations (parallel, perpendicular, 45°, and normal) and volume of fibre fractions (20–35%) were used for the analysis. The properties of the materials were incorporated into the ANSYS Engineering database, and the composite model was divided into five segments to analyse the heat transfer. The thermal boundary condition was implemented by keeping one side of the cylinder at 120°C. The results showed that the thermal conductivity of the composites decreased as the volume fraction of natural fibres increased. Epoxy-based composites exhibited better insulation performance than polyester and vinyl ester-based composites. This study demonstrated the potential of using natural fibres to improve the thermal insulation properties of composites.
... This nature restricts their suitability with hydrophobic matrices of polymer, leading to amalgams with elevated H2O absorption capabilities. This issue has been highlighted in research work (Zhang et al., 2014;Zheng, 2014;Pereira et al., 2015). The high susceptibility to water leads to fiber swelling and a plasticizing effect, causing dimensional instability and a decline in mechanical properties (Bismarck et al., 2002). ...
Cannabis sativa, sometimes known as industrial hemp, is frequently used for manufacturing of high-cellulose bast (highly fibrous) fibers. The need for environmental conservation, combined with the beneficial characteristics of these fibers like their low thickness, high definite forte, and toughness prompts a strong interest in their utilization. Additionally, a great deal of effort has been put into developing novel materials thus improves the mechanical performance through surface modifications. Hemp fibers' most promising uses involve hybridization or as reinforcement in polymeric composites. However, more research is required to enhance their properties and broaden the scope of their uses. In the context of long-lasting applications and the ability to consistently reproduce the desired qualities of these composites, one significant concern is the biodegradability aspect, which requires careful consideration. This review offers a comprehensive examination of the existing body of research on hemp fibers, encompassing aspects such as the mechanical as well as chemical properties of hemp fibers, surface enhancements, hybrid composite materials, and both current and prospective applications.
... Chemical composition and properties of single hemp fibreFig. 3. HF structure: (a) a section through the middle of the HF stem[44], (b) the morphology of the HF bundle[45], and (c) a simplified representation of the fundamental HF[6] ...
Fibres have long been used as an additive in the fabrication of building elements and
materials. A combination of natural and synthetic fibres has shown promise in
preliminary research and testing, with the added benefit of greatly improved strengths
of the composites. Compared to traditional reinforcement bars, natural fibre
reinforcement's ratio of fibre required is significantly lower, making it more beneficial
in terms of energy and economic values. Recent research has focused on the feasibility
of using both natural and synthetic fibres as reinforcement in concrete and other
construction materials. Thus, the purpose of this research is to investigate the
feasibility of using hemp fibre at various percentages (0%, 0.2%, 0.4%, 0.6%, and 0.8%)
as an additive in lightweight foamed concrete to enhance mechanical properties. Three
LFC densities namely 500, 900 and 1300 kg/m3 were fabricated and tested. Axial
compressive strength, flexural strength, splitting tensile strength, and ultrasonic pulse
velocity were the four mechanical parameters that were assessed. The findings
demonstrated that adding 0.4-0.6% of HF to LFC produced the best results for
ultrasonic pulse velocity, compressive strength, flexural strength, and splitting tensile
strength. The HF is essential in assisting to stop the spread of cracks in the plastic state
of the cement matrix after the load was applied.
... Yaygın olarak keten kumaş olarak bilinen yaklaşık 4500 yıl önce keten kumaş bulunduğu Taş Devrinden beri dikkat çekmiştir (11). Keten lifi dünyanın birçok ılıman ve subtropikal bölgesinde doğal olarak yetişen Linum usitatissimum'un sapından gelir (33,34). Fransa, Rusya, Kanada, Belçika ve Çin'de lif ve yağ için keten yetiştirilmektedir. ...
Uzay, Havacılık ve Otomotiv Endüstrileri yakıt tasarrufunu arttırmak amaçlı hafif
bileşenlerin geliştirilmesi yönünde sürekli çalışmalar yürütmektedir. Termoplastik
matrisli kompozitler ağırlık azaltma, geri dönüşebilirlik, özgül mukavemet, korozyon direnci artırma, maliyet düşürücü ve tasarımın çok yönlü açısını belirgin hale getirmek
için araştırmalar yürütülmektedir (1). Doğal Lifler biyolojik olarak parçalanabilmeleri, doğada bol olmaları ve düşük maliyetleri sayesinde bu malzemelerin kapsamını genişletmekle
kalmaz aynı zamanda petrol bazlı ürünlere olan bağımlılığı da azaltır. Bu yazımızda doğal
liflerin özellikleri konusunda kapsamlı bir son teknolojiden bahsedeceğiz. Ağırlıklı olarak
bitki lifleri ve bunların kompozit takviye olarak kullanımı, ardından mühendislik mimari
ürün üretmek için kullanılan tekstil teknolojilerinden bahsedeceğiz (1). Ayrıca herhangi
bir spesifik ürün geliştirme için kesin malzeme ve sürecin seçimini sağlamak için yaygın
olarak bulunan termoplastik matrislerin özelliklerini ve kompozit üretim tekniklerini de
kapsar. Son olarak doğal elyaf takviyeli termoplastik kompozitlerin mekanik özellikleri
gözden geçirilmiş ve ele alınması gereken temel zorluklar vurgulanmıştır.
... Cross-section of hemp fibre, reprinted from Hindawi[36] under the Creative Commons Attribution License. ...
The automotive and aerospace industries are in continuous struggle towards the development of lightweight components to improve fuel efficiency. Thermoplastic matrix composites offer distinct advantages in terms of weight reduction, recyclability, specific strength, corrosion resistance, cost-efficiency, and design versatility. Natural fibres owing to their biodegradability, abundance in nature, and low cost not only expand the scope of these materials but also curtail the dependency on petroleum-based products. This review presents a comprehensive state of the art in natural fibres properties; mainly plant fibres, and their use as composite reinforcement followed by the textile technologies used to fabricate the engineered architectures. The review also covers the properties of commonly available thermoplastic matrices and the composite fabrication techniques to enable the selection of the precise material and process for any specific product development. Finally, the mechanical properties of natural fibre reinforced thermoplastic composites are reviewed and the key challenges that need to be dealt with are highlighted.
... Since lumen of the natural fiber bundle is hollow over its length, thermal conductivity of the lumen region is equivalent to the air. Thus for the lumen region, thermal conductivity of 0.026 W/mK was substituted in the micromechanical models during the computation [16]. Therefore with the boundary conditions shown in Fig. 2.1A and B and the thermal conductivity of the polymer and lumen, longitudinal (k cII ) and transverse thermal conductivity (k c ⟘ ) of the natural fiber can be estimated. ...
... As the number of lumens increased in the fiber bundle, characteristics of the biocomposite changed from anisotropy to isotropy [19]. In his study, Zheng also found that k cII and k c ⟘ along the longitudinal and transverse directions were identical for the hemp fiber bundle with 106 number of lumens (taken based on the count in the microstructure of the hemp fiber bundle) [16]. Thus it is clear ...
... Schematic of 2D square-shaped RVE with single fiber bundle embedded in the polymer matrix: (A) boundary condition for kcII and (B) boundary condition for kc ⟘[16].Rule of mixture modelsVoigt model (upper bound)-longitudinal thermal conductivity parallel to the fiber cell/axis (k cII )k cII = k fII v f + k m v m + k v + v vReuss model (lower bound)-transverse thermal conductivity perpendicular to the fiber cell/axis (k c ⟘ Arithmetic mean for mixed orientation k c = k cII ε + k c ⟘ (1 − ε) ε is the fitting factor used as weightage for relative contribution from the longitudinal and perpendicular cells to the fiber axis.v f , v m and v v are volume fractions of fiber, matrix and void in the composite.Halpin-Tsai model (for longitudinal and transverse thermal conductivity) , k f = k fII or k f ⟘ ε is a geometric fitting factor-usually two times the longitudinal aspect ratio for k c = k cII and k f = k fII and two times the transverse aspect ratio for k c = k c ⟘ and k f = k f ⟘ . ...
Mechanical and thermal properties of biocomposite reinforced with natural fibers have been determined traditionally from the experimental testing methods. This process is labor intensive, expensive and time-consuming. Hence, with the advancement of computational tools, modeling and analysis of the composites have become feasible. Finite element method (FEM) is a common tool used for the prediction of mechanical and thermal properties of the biocomposite. FEM-based computational analysis is relatively new and has great scope for research. Micromechanical, macromechanical and mesoscale analyses of finite-element models were used for the prediction of strength and stiffness of biocomposites. For thermal analysis, studies involve determining the thermal conductivity and analyzing the cure kinetics of the biocomposite. Hence, this chapter focuses on the various computational models used for predicting the mechanical and thermal properties of the biocomposite.
... Hemp fiber has a multi-celled structure, which can be seen as a composite material with numerous lumens side by side ( Figure 1b) [18,28,37]. A typical elementary fiber structure of hemp fiber is shown in Figure 1c. ...
... The retting processing for up to three weeks did not affect the tensile strength of the hemp fibers. [42]), (b) cross-section morphology of the hemp fiber bundle [37], and (c) schematic depiction of hemp elementary fiber (adapted from [38]). ...
Industrial hemp (Cannabis sativa) is one of the most available and widely produced bast fibers with high cellulose content. Interest in these fibers is warranted due to environmental protection challenges as well as their inherent properties such as low density, high specific strength, and stiffness. In addition, advanced research and progress have gone into increasing their mechanical performance through surface treatments and in the development of new materials. The most promising application for hemp fibers is as reinforcement in polymeric composites or through hybridization. Nonetheless, more research is needed to improve their properties and expand their range of applications. The biodegradability issue is one problem that must be addressed when considering long life-cycle applications as the reproducibility of these composites’ final properties. This review is a comprehensive literature review on hemp fibers. It includes hemp fibers’ chemical and mechanical properties, surface modifications, hybrid composites, as well as current and future applications.
... These properties are used in this paper as an input for the FE model constituted for determining the stresses and strains for the specific failure load and life as determined by experiments. The behavior of the natural fiber composites was predicted frequently in the literature using FE modeling [35][36][37][38][39][40] for determining micromechanical properties (strength, failure, deformation, and damage) [41][42][43], macro shape deformation (fracture and stress-strain) [44][45][46][47] and thermal conductivity [48,49]. The representative volume element model was considerably reported in the literature along with the multi-scale homogenization-based constitutive method. ...
The objectives of present work include finding the low-cost alternative of environmentally-unsafe carbon fiber composites and disposing of the waste cow-dung productively. An inexpensive way to treat cow-dung fibers using the waste glass powder and Poly Vinyl Alcohol (PVA) adhesive is reported. The treatment has increased the bending cyclic fatigue strength (CFS) of cow-dung fiber reinforced epoxy composite (CDFRC). It was found that CFS of CDFRC was comparable to carbon fiber reinforced epoxy composite (CFREC). A finite element (FE) model using the numerical homogenization technique was constituted to predict the elastic properties of treated/untreated CDFRC. Further, the predicted elastic properties were used as an input for the macro-mechanical FE model constituted using transient analysis module of ANSYS. The macro model was used to calculate the stresses and deformations at different load ratios (R) for the corresponding lives of the CDFRC. The stress-strain-life relations for treated/ untreated CDFRC were established. The reasons for increased CFS were identified collectively with the help of scanning electron microscopy (SEM) micrographs, FE results, and statistical analysis. Finally, the effect of natural weathering on untreated and treated CDFRCs was evaluated. The treated CDFRCs have shown higher resistance to natural weathering.
... However, the microstructure of natural fibers consists of a solid region and lumen, which strongly affects the thermal properties of NFRPC. To overcome this issue a 2D RVE model was created [18]. Fig. 9.8 shows the 2D model of the NFRPC. ...
Natural fibers, which are abundantly available in nature, and natural fiber-reinforced polymeric products have been widely used in nonload-bearing structures in recent years. Human error and accuracy of the results from the testing machine make the experimental evaluation of the properties of natural fiber-reinforced composites less realistic with a high degree of variation in the measured properties. Evaluation of the mechanical, thermal, and other properties of natural fibers and natural fiber-reinforced polymer composites using finite element analysis helps to overcome these limitations. Due to the complicated structures in different length scales it is essential to use a homogenized computational method to evaluate the relationship between micro- and macrostructural behavior. The representative volume element method is the most efficient homogenization-based multiscale finite element model and it represents the relevant features of natural fiber in a uniform microstructure. This chapter addresses the introduction of finite element analysis, basic steps, and an overview of the modeling/simulation procedure for natural fiber-reinforced polymer composites.
... The transverse thermal conductivity of NF obtained from FEA was in accordance with that calculated from Hasselman-Johnson's model. 70 Zheng 67 investigated the effect of thermal property of the solid region phase and lumen on the equivalent anisotropic thermal property of the NF bundle. The relationship between the thermal conductivities of the solid region phase, lumen and the NF bundle was established through polynomial fitting on the FEA results. ...
... The flax fiber was modeled as a linear isotropic elastic material and the PP resin was modeled as a non-linear plastic material. 78 In addition, the defects of flax fibers and interface between fiber bundles were modeled as a Evaluating the transverse thermal conductivity of fiber considering the influence of lumens Zheng 67 Natural fiber 2D RVE of the cross-section of fiber bundle ...
Finite element method has been widely applied in modeling natural fibers and natural fiber reinforced composites. This paper is a comprehensive review of finite element models of natural fibers and natural fiber reinforced composites, focusing on the micromechanical properties (strength, deformation, failure, and damage), thermal properties (thermal conductivity), and macro shape deformation (stress–strain and fracture). Representative volume element model is the most popular homogenization-based multi-scale constitutive method used in the finite element method to investigate the effect of microstructures on the mechanical and thermal properties of natural fibers and natural fiber reinforced composites. The representative volume element models of natural fibers and natural fiber reinforced composites at various length scales are discussed, including two types of geometrical modeling methods, the computer-based modeling method and the image-based modeling method. Their modeling efficiency and accuracy are also discussed.
