Research On Protection Of Child-pedestrian Head Injury In Vehicle-pedestrian Collisions

In car to pedestrian accidents, pedestrians are the most vulnerable road users due to short of protection measures, which lead to high frequency accidents on pedestrians. Pedestrians under 15 years old are one of the groups taking part in accidents. Children accounts for 18percents of the whold people but involved in one third of the pedestrian accidents. Statictical results show that head is the most frequently injured body of the children in the accidents, and usally the main cause leads to death.The purpose of the paper is to study the relationship between the change of bonnet structural and material with the child head-form`s HIC value and intruasion. Study on influence of vehicle front structural dimension to child head injury paramenters in real world is performed based on real accident reconstructions and many corresponding improvement measures are put forwards.Child finite element head-form from ARUP Company is employed to develop the simulation model of head-form impacting with the bonnet based on the EURO-NCAP testing regulation, and validation is performed base on the literature. The relationship between the change of bonnet structural and material with the child head-form acceleration and intrusion is studied.Three real accidents involved 3children are reconstructed to understand the child head kinimatics response, and injury paramenters closely related with child head injury ara analylised such as linear head acceleration, HIC value, head angular velocity and acceleration and relative impact velocity and so on.Among the three reconstructions, the 7-year-old child accident model is employed as the reference model for paramenter study. The range of vehilcle front stuctrure dimensions is defined by referring to statistical data. Orthogonal array is applied to determine the testing points. Drawing trendline picture and relative error analysis are employed to help to study the influence and importance of front structures of passenger car on child pedestrian head injuries, and the results are copmpare with the adult pedestrian.The study results show that decreasing the thickness of the bonnet without hard points underneath can improve the protection effective to the head, but to the zones with hard points underneath and near the fenders decreasing the thickness of bonnet may get an opposite result.The protective effect of alluninium bonnet is better than the steel bonnet. Increasing easily deformable and energy asorbing structrures can improve the protective effect of the impact zones near the edge of bonnet effectively. The head impact conditions are greatly variable according to the change of child weight, height and the car front structures. The passenger car front structural paramenters are more prominent to the child head injury than to the adult`s. Increasing the heigh of bonnet edge appropriately can get a better protective effect for both child and adult pedestrians.This study provides an effective approach and simulation method for research on injury biomechanics and development of protection measures for child pedestrian head. The simulation conlusions can be used as a reference to vehicle safety design.