Strength and healing efficiency of helicoidal carbon fiber reinforced thermoplastic laminates

Bio-inspired helicoidal CFRP laminates have been shown to sustain higher loads than conventional laminates. Such works have focussed on thermoset systems. A first attempt to adopt helicoidal thermoplastic laminates is presented. Not only were higher loads achieved, but the thermoplastic laminates could also be healed effectively with heat and pressure after impact. The high inter-laminar toughness of thermoplastic laminates meant that ply blocking can be exploited to increase ply toughness without suffering detrimental delamination. The optimal helicoidal configuration with ply blocking showed a 52% higher out-of-plane strength than other configurations. Ply blocking minimized fiber damage, and consequently improved healing efficiency. Hence, helicoidal lami-nates with higher levels of ply-blocking that were subjected to impact loads fully recovered their strength and stiffness after healing. Helicoidal laminates with lower level of ply-blocking suffered fiber damage but could still recover their stiffness.