Enhanced impact energy absorption and failure characteristics of novel fully thermoplastic and hybrid composite bicycle helmet shells

Current research realize to develop a safer, lighter and higher energy absorbing fully thermoplastic (polypropylene fibres and acrylic Elium resin) and hybrid composite helmets (polypropylene/carbon hybrid and Elium resin) and perform the CPSC 1203 certification tests on different anvils. The failure and energy absorption mechanisms were studied and compared with widely used polycarbonate helmets (PC/EPS) and the composite shells manufactured with epoxy resin. The fully thermoplastic and hybrid composite shells have shown up to 65% of absorbed energy while the polycarbonate shells have absorbed a maximum of 13% of the absorbed energy. The usage of composite shells has lead to minimal energy transfer to the foam which is directly attached to the human head and provided improved safety. The high-speed camera has shown clear deformation of the thermoplastic composite shell owing to the ductile behaviour while the catastrophic failure with significant cracks was observed in the Epoxy-based composite shell. Considering the head injury criteria, the PC/EPS helmet showed the highest fatality rate (6%) when impacted on the flat anvil. The usage of fully thermoplastic and hybrid composite shell reduces the probability of critical and fatal injury by around 40% and 60% respectively when compared to PC/EPS configuration.