Feasibility of using Duraform® flex lattice structures and additive manufacturing for optimising bicycle helmet design safety

Bicycle helmets are designed to attenuate forces and accelerations experienced by the head during cycling accidents. An essential element of bicycle helmet design is, therefore, the appropriate manufacturing of energy dissipating components. The focus of this study was to evaluate the feasibility of using elastomeric lattice-based structures (Duraform® Flex), manufactured via a laser sintering (LS) process, as the energy dissipating inner liner of the bicycle helmet. This study is presented in two sections; the optimisation of the LS process capabilities for the manufacture of lattices based structures and an evaluation of the effects of lattice structure density on helmet impact kinematics. Through the fabrication and testing of tensile and compressive specimens, each process parameter (laser power, scanning exposure, build temperature and part orientation) was optimised to maximise compressive strength. The energy dissipating characteristics of helmet lattice structures, made from this optimised material, were evaluated during simulated helmeted headform impact tests. Reduced accelerations and increased pulse durations were reported for decreased lattice structure densities, demonstrating improved energy dissipating characteristics for this novel technique. This study demonstrates that lattice-based inner liners, manufactured via additive manufacturing processes, have exciting potential towards improving bicycle helmet safety