Development and impact characterization of acrylic thermoplastic composite bicycle helmet shell with improved safety and performance

Abstract

Fiber-reinforced composites are increasingly used as an outer shell of sporting helmets as an alternative to conventional thermoplastic shells like Acrylonitrile butadiene styrene (ABS), Polyurethane (PU), and polycarbonate (PC) for improved protection. The current research presents a detailed study to manufacture novel woven carbon/Elium® (WEL) thermoplastic composite helmets and investigate the details based on the impact tests following the industrial safety certification criteria (CPSC 1203 helmet certification) tests on the flat, curb-stone, and the hemispherical anvils. The effect of thermoplastic Elium® resin toughened thermoplastic Elium® IM, and Epoxy resin is investigated to understand the benefits offered by the thermoplastic variants in terms of safety, energy absorption, and the impact failure mechanisms. Post-failed Carbon/Elium® thermoplastic composite shells have shown more ductile and less catastrophic damage as opposed to the Carbon/Epoxy composite shell damage. The impact damage mechanisms as observed from the in-situ high-speed camera images have shown more deformation-dominated failure mechanisms for the composite shells manufactured with Elium® and toughened Elium® resin. Carbon/Epoxy composite shells have shown lower energy absorption and the nature of the failure was more catastrophic and more cracks were noticed on the inner side of the foam which is directly attached to the human head. In case of an impact on a flat anvil, the PC shell configuration has shown a critical injury rate of 28.7% and a fatality rate of 6%. With the manufactured Carbon/Elium® composite helmets, the chances of critical and fatal injury rates are reduced to 16.7% and 3% respectively.