Comparative Analysis of Flax Fiber-Reinforced Composites and Hybrid Configurations for Enhanced Low Energy Impact Performance

In this study, the low energy impact properties of flax/epoxy, glass/epoxy and hybrid flax-glass/epoxy laminates are evaluated for two different stacking sequences: a unidirectional [0] 8 and a cross-ply [0/90] 2s . For flax laminates, the base reinforcement is made of the combination of a unidirectional flax layer and a flax mat layer, where the mat phase consisted of short flax fibers used as a binder for the unidirectional phase. All laminates were tested under uniaxial tension both before and after impact and were molded at a fiber volume fraction of 40%. The results indicate that the specific stiffness of the flax fiber composite is approximately 7% higher than that of the glass fiber composite, regardless of the stacking sequence used. Concerning low-energy impact resistance, the cross-ply laminate demonstrates superior performance with higher impact resistance and less permanent deformation compared to the unidirectional laminate. The study also explores the hybridization of flax and glass fibers, suggesting a promising approach that leverages the synergistic effects of employing two different types of fibers in the composite. The comparison of energy absorption during impact shows that the hybrid fibers/epoxy composite has a higher energy absorption capacity than the glass fiber/epoxy composite. Additionally, hybridization helps mitigate the degradation of tensile properties caused by impact, representing an effective strategy to enhance the mechanical properties of the flax fiber composite post-impact.