Journal of Forensic Biomechanics

Abstrait

A Novel Strategy for Mitigation of Oblique Impacts in Bicycle Helmets

Emily Bliven, Alexandra Rouhier, Stanley Tsai, Rémy Willinger, Nicolas Bourdet, Caroline Deck, Steven M Madey and Michael Bottlang

A principal cause of traumatic brain injury is rotational head acceleration, which can induce brain injury even in absence of a direct impact to the head. A bicycle fall typically leads to an oblique impact of the head that induces rotational head acceleration. To mitigate this rotational head acceleration, a novel bicycle helmet concept has been developed that employs a collapsible cellular structure. This study quantified the efficacy of this technology in comparison to traditional bicycle helmets made of rigid Expanded Polystyrene (EPS). Prototype helmets  with the Cellular structure (CELL) and standard EPS helmets (CONTROL) were subjected to oblique impacts in vertical drop tests onto angled anvils. Helmets were tested at impact speeds of 4.8 m/s and 6.2 m/s and at impact angles of 30°, 45°, and 60°. Linear and rotational headform acceleration and neck loads of an anthropometric head-neck surrogate were recorded and peak axonal strain was estimated from headform kinematics. CELL helmets significantly reduced rotational acceleration and associated axonal strain in all tests compared to CONTROL helmets, with reductions ranging from 34%-73% for rotational acceleration and 63%-85% for axonal strain. Results demonstrate the potential of the novel bicycle helmet strategy to reduce rotational head acceleration and axonal strain associated with brain injury risk.