Japanese accident statistics show that despite the decreasing trend of the overall traffic fatalities, more than 1,000 pedestrians are still killed annually in Japan. One way to develop further understanding of real-world pedestrian accidents is to reconstruct a variety of accident scenarios dynamically using computational models. Some of the past studies done by the authors' group have used a simplified vehicle model to investigate pedestrian lower limb injuries. However, loadings to the upper body also need to be reproduced to predict damage to the full body of a pedestrian. As a step toward this goal, this study aimed to develop a simplified vehicle model capable of reproducing pedestrian full-body kinematics and pelvis and lower limb injury measures.
The simplified vehicle model was comprised of four parts: windshield, hood, bumper and lower part of the bumper. Several different models were developed using different combinations of geometric and stiffness representation. A unique model called a multi-layer model developed in this study represented each of the hood and the windshield with a stack of the panel representing the entire area of these components, while applying localized stiffness characteristics and contact definition with a particular pedestrian body region that contacts with the layer represented by the stiffness characteristics. These models were made to collide with the human FE model, and pelvis and lower limb injury measures and full-body kinematics were compared with those from the simplified vehicle models.
The results of the comparisons showed that the multi-layer model provided a more realistic contact interaction between the pedestrian body and the vehicle by eliminating the gap between adjacent panels due to geometric division of a large vehicle body panel.