Fatigue Behavior Comparison of Inter-Ply and Intra-Ply Hybrid Flax-Carbon Fiber Reinforced Polymer Matrix Composites

Hybridization of natural fiber with synthetic fiber to reinforce polymer matrix composites is an effective way of increasing fatigue strength of composites with substantial amount of bio-based content. Flax is the strongest type of bast natural fiber, possessing excellent mechanical and damping properties. Fatigue properties of flax fiber hybridized with synthetic carbon fiber reinforced polymer matrix composites were studied. Fatigue properties of inter-ply hybrid flax-carbon fiber reinforced composite were compared to intra-ply hybrid flax-carbon fiber reinforced composites through tensile fatigue testing at 70% load of ultimate tensile strength and with a loading frequency of 3 Hz. For similar amount (by mass) of flax and carbon fiber, intra-ply flax-carbon fiber hybrid reinforced composite exhibited a very large increase (>2000%) in fatigue life compared to inter-ply flax-carbon fiber hybrid reinforced composites. Suitable hybridization can produce hybrid composites that are as strong as synthetic fiber composites while containing a high bio-based content of natural fibers.