Tensile and compressive damaged response in Flax fibre reinforced epoxy composites

Multiscale characterization of the textile preform made of natural fibers is an indispensable way to understand and assess the mechanical properties and behavior of composite. In this study, a multiscale experimental characterization is performed on three-dimensional (3D) warp interlock woven fabrics made of flax fiber on the fiber (micro), roving (meso), and fabric (macro) scales. The mechanical tensile properties of the flax fiber were determined by using the impregnated fiber bundle test. The effect of the twist was considered in the back-calculation of the fiber stiffness to reveal the calculation limits of the rule of mixture. Tensile tests on dry rovings were carried out while considering different twist levels to determine the optimal amount of twist required to weave the flax roving into a 3D warp interlock. Finally, at fabric-scale, six different 3D warp interlock architectures were woven to understand the role of the architecture of binding rovings on the mechanical properties of the dry 3D fabric. The results reveal the importance of considering the properties of the fiber and roving at these scales to determine the more adequate raw material for weaving. Further, the characterization of the 3D woven structures shows the preponderant role of the binding roving on their structural and mechanical properties. Fibers 2020, 8, 15 2 of 14composites. These works showed that the architecture of the reinforcement has a preponderant role on the mechanical properties of the composite.Generally, 3D architectures can be obtained by combining multi-layers of stacked 2D fabric with a through-the-thickness fiber reinforcement, introduced using stitching, z-pining, or tufting technologies [10][11][12]. Another technology is the 3D warp interlock weaving, in which multi-layers of in-plane yarns are bound together by a group of binding warp yarns according to a specific architecture (light blue in Figure 1) [13]. Consequently, in 3D warp interlock weaving, a thick structure is formed without degradation to the in-plane fibers that results from needle insertion through-the-thickness in the stitching and tufting techniques. Moreover, the fiber reinforcement through-the-thickness direction is inserted during the weaving and no further steps are required.ibers 2020, 8,15 2 o

Section: Fiber Characterizationsupporting

confidence: 92%

Development and Multiscale Characterization of 3D Warp Interlock Flax Fabrics with Different Woven Architectures for Composite Applications

Lansiaux

Soulat

Boussu

et al. 2020

“…All the curves exhibited a significant non-linear behavior at low strains, which needs to be ascribed to the presence of flax fibers and seems only to be emphasized by the ductile PP. Many authors have pointed out this behavior [33,34] that seems to represent a peculiarity of natural fibers, as it has been reported to occur not only in flax [35,36] but also in wood [37] and hemp [38]. Recent studies tried to provide explanations for this behavior, and several mechanisms have been proposed, including cellulose microfibrils reorientation, shear strain-induced crystallization of the amorphous paracrystalline components and degree of ellipticity of the fiber's cross-section [38,39].…”

Section: Quasi-static Flexural Behaviourmentioning

confidence: 98%

Quasi-Static and Low-Velocity Impact Behavior of Intraply Hybrid Flax/Basalt Composites

Sarasini

Tirillò

Ferrante

et al. 2019

In an attempt to increase the low-velocity impact response of natural fiber composites, a new hybrid intraply woven fabric based on flax and basalt fibers has been used to manufacture laminates with both thermoplastic and thermoset matrices. The matrix type (epoxy or polypropylene (PP) with or without a maleated coupling agent) significantly affected the absorbed energy and the damage mechanisms. The absorbed energy at perforation for PP-based composites was 90% and 50% higher than that of epoxy and compatibilized PP composites, respectively. The hybrid fiber architecture counteracted the influence of low transverse strength of flax fibers on impact response, irrespective of the matrix type. In thermoplastic laminates, the matrix plasticization delayed the onset of major damage during impact and allowed a better balance of quasi-static properties, energy absorption, peak force, and perforation energy compared to epoxy-based composites.

“…Research into flax fibre reinforced epoxy composites [6] suggests that while flax may be considered one of the strongest natural fibre replacements for synthetic fibres, data on the transverse, shear, and compressive response of flax reinforced components is limited. The study found that delamination and fibre breakage is most prevalent in shear failure; while defibrillation and fibre cracking is presents under tensile loading.…”

Section: Introductionmentioning

confidence: 99%

Effects of Hybridisation on the Low Velocity Falling Weight Impact and Flexural Properties of Flax-Carbon/Epoxy Hybrid Composites

Chapman

Dhakal

2019

The trend of research and adoption of natural plant-based fibre reinforced composites is increasing, with traditional synthetic fibres such as carbon and glass experiencing restrictions placed on their manufacture and use by legislative bodies due to their environmental impact through the entire product life cycle. Finding suitable alternatives to lightweight and high-performance synthetic composites will be of benefit to the automotive, marine and aerospace industries. This paper investigates the low-velocity impact (LVI) and flexural properties and damage characteristics of flax-carbon/epoxy hybrid composites to be used in structural lightweight applications. LVI, for example, is analogous to several real-life situations, such as damage during manufacture, feasibly due to human error such as the dropping of tools and mishandling of the finished product, debris strikes of aircraft flight, or even the collision of a vessel with another. Carbon fibre has been hybridised with flax fibres to achieve enhanced impact and flexural performance. The failure mechanisms of woven flax and flax-carbon epoxy hybrid composites have been further analysed using Scanning Electron Microscopy (SEM). It was observed from the experimental results that carbon fibre hybridisation has a significant effect on the impact and flexural properties and their damage modes. The results obtained from this study exhibited that the flexural strength and modulus of plain flax/epoxy composite increase significantly from 95.66 MPa to 425.87 MPa and 4.78 GPa to 17.90 GPa, respectively, with carbon fibre hybridisation. This significant improvement in flexural properties would provide designers with important information to make informed decisions during material selection for lightweight structural applications.