Effects of Half-Face Helmets on Motorcyclist Head Injuries: A Finite Element Simulation Study with Experimental Validation

Motorcyclists frequently sustain severe head injuries in traffic accidents, particularly in Southeast Asian nations where the use of half-face helmets remains widespread. This study investigates the effects of impact speed and impact location on the severity of head injuries, including potential traumatic brain injury. Numerical simulations were conducted using the Vietnamese-Total Human Model for Safety (V-THUMS) alongside a validated finite element model of a half-face helmet to perform comprehensive numerical simulations. Experimental validation of the helmet model was achieved through drop tests conducted at the Quatest 3 Center. A comparative analysis of simulated and experimental acceleration, time histories demonstrated comparable response characteristics, with a minimal deviation of 3.1% in peak acceleration, confirming the reliability of the finite element model. The helmeted V-THUMS head was subjected to impact at four locations, including: forehead, occipital, temple, and vertex, across speeds ranging from 2 to 8 m/s. The Head Injury Criterion (HIC), peak linear acceleration (PLA), and strain energy absorbed by the helmet foam were calculated to elucidate the injury mechanisms. The results indicate that the helmet foam layer absorbs approximately 84.1% of the total strain energy, significantly mitigating impact severity. Wearing a helmet significantly reduces the HIC value by up to 74.8% compared to unhelmeted scenarios and effectively prevents critical head accelerations that may lead to brain injury. However, impacts exceeding 8 m/s markedly diminish the protective capacity of the helmet, decreasing it considerably, presenting an escalated risk of severe or fatal injury. These findings not only clarify the protective performance of half-face helmets under diverse impact conditions but also provide practical insights for helmet design improvements and the revision of safety standards aimed at enhancing head protection in real-world motorcycle collisions.