This study investigates the impact response of gyroid lattice structures as liner-absorbing pads for motorcycle helmets. An experimental drop test analysis was conducted on a commercial helmet, utilising its overall dimensions to develop a numerically modelled helmet. The impact performance was then validated, demonstrating good agreement between the experimental and numerical acceleration histories. After, the helmet liner was then segmented into four impact regions (i.e., Impact Liner: Rear, Frontal, Superior, and Lateral) and coupled into a biomechanical head model (THUMS male detached head), where an oblique impact was conducted at 7 m/s, and the helmet responses were evaluated through brain damage levels. A transversely anisotropic crushable foam was used to analyse sensitivity and identify the most influential parameters influencing brain damage levels. This led to a numerical optimisation process that resulted in the development of an idealised helmet liner. Finally, the gyroid lattice structure was integrated into the liner to optimise the thickness for oblique impact conditions in all impact liner regions. The results demonstrated a significant reduction in brain damage across all impact regions, with improvements of 1% to 28% in Lateral and frontal areas, respectively, highlighting the potential of lattice structures to enhance motorcyclist safety. The methodology proposed here can support future developments in the use of lightweight lattice structures as helmet liners.
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