Abstract
The purpose of this study is to examine the mechanism of head rotation and the effects of cyclist helmets on the reduction of brain injury risk in A-pillar impact in car-to-cyclist collisions. Finite element analyses where a car model collided with a helmeted and unhelmeted human model placed on a bicycle model were performed. In this simulation, the occipital region of head impacted on the A-pillar. Although the helmet can reduce impact force, angular velocities of the head and moments of force applied to the head remained high because of direct contact of the occipital region of head to the A-pillar and bottoming out of the helmet liner. It was found that there are some cases that helmets cannot reduce brain injury risk in A-pillar impacts
