Abstract
In Japan, as we have many cases of traffic accidents involving children on the school-commuting roads, some local governments require the students to wear helmets designed for bicycle rider due to no standard product of helmets for pedestrians. Because the effectiveness of their currently wearing helmets is not proved, it is necessary to develop a safety standard applying to pedestrian helmets. However, the correlation between pedestrians' walking posture and head injuries, and also between protective effect of helmet and injuries without skull fractures, such as subdural hematomas, has not been clearly resolved. The purpose of this study is to analyze these issues and propose a safety standard. A pedestrian-vehicle collision simulation was conducted using the multi-body dynamics analysis software “MADYMO”. The walking posture of a pedestrian and the head protection with or without a helmet were alternately analyzed to investigate the effects on crash behavior and head injury. Injury risk due to skull fracture was evaluated by Head Injury Criteria based on translational acceleration of the head, and injury risk due to subdural hematoma was evaluated by the change range of angular velocity of the head. This study has shown that the risk of injury suffered from traffic accidents depends on not only the velocity of the vehicle but also the walking posture. Therefore, it is necessary to consider the whole- body behavior when evaluating the performance of pedestrian helmets. Another study has resulted that the helmet suppresses the head bounce following the collision, and reduces the change range of head angular velocity. However, the transition of the angular velocity with the change in collision velocity has been different compared to the analysis data without the helmet. Therefore, it is necessary to consider not only translational acceleration but also angular velocity of the head in the performance evaluation of helmets.
