Head boundary conditions in pedestrian crashes with passenger cars: six-degrees-of-freedom post-mortem human subject responses

Abstract

In pedestrian–vehicle crashes, head injuries cause death and long-term disability. Thus, understanding the head kinematics is vital. Head rotation data are scarce, and the influence of individual anthropometry, upper body and arm kinematics on head kinematics is poorly understood. This paper investigates the influence of anthropometry, upper body and arm kinematics on head linear and angular kinematics, providing novel six-degrees-of-freedom data from pedestrian–vehicle-crash experiments. Five similarly positioned subjects were struck by a mid-size sedan at 40 km/h. Three-dimensional translation and three-dimensional rotation of the head, spine and shoulders were compared. Head kinematics differed considerably among the subjects. Variations in anthropometry changed pelvic sliding towards the windshield. Arm responses altered head impact velocity and head rotation. The results have implications for future experiments, evaluation of human models and the design of pedestrian safety systems. Head injury risk can be moderated by reducing head rotation before head impact, and by reducing pelvic sliding.