Effects of hybridization and hybrid fibre dispersion on the mechanical properties of woven flax-carbon epoxy at low carbon fibre volume fractions

Natural and synthetic fibers are increasingly being used as reinforcements in various applications. While the latter is popular for its generally superior mechanical properties, natural fibers are eco-friendly, cheap and have good vibro-acoustic properties. As more businesses are investing in green and sustainable technologies, natural fibers have been gaining attention in recent years and are already being used in various applications such as car interior, sporting equipment, etc. To date, their applications have been limited to those not requiring very demanding mechanical performance. In this paper, mechanical performance enhancement of natural fiber composites through hybridization with carbon fibers was benchmarked against one of the strongest and stiffest natural fibres, flax, through various interlayer flax-carbon hybrids at low carbon fibre volume fractions. Besides strength and stiffness characterization of hybrid laminates, this work investigates the effects of interlaminar hybrid fiber dispersion on tensile performance. The results suggested that morphology of mating hybrid plies might affect stiffness in woven fabrics. Hybrid laminates with single carbon plies interspersed with flax plies displayed lower tensile stiffness due to absence of nesting of the stiffer woven carbon plies and architectural crimp mismatch between flax and carbon woven fabrics. Comparisons with rule of hybrid mixture predictions showed reasonably good agreement in hybrid laminates exhibiting linear behavior, but significant over-predictions in highly dispersed laminates due to large deviations from linearity.