Investigation of the injury threshold of knee ligaments by the parametric study of car–pedestrian impact conditions

Abstract

Pedestrian safety is a serious global problem that needs to be addressed by drivers, vehicle manufacturers and researchers. Since the first European Committee directive for pedestrian safety was published, vehicle suppliers have implemented pedestrian protection requirements to automobile structures at the design level. As to the development of current automobile front-end structures, a question arises about pedestrian safety: are there existing injury criteria for the new generation of cars? Most previous injury thresholds for knee ligaments were principally based on isolated sub-segment tests with contrived loading conditions, and rarely took the entire front-end shape of the car model into account to simulate realistic pedestrian loading conditions. Hence, the current study aims to investigate injury thresholds of primary knee ligament injuries in car–pedestrian impact environments as well as to evaluate the previous criteria proposed by isolated sub-segment tests. The entire front-end shape of a car model was employed. A parametric study of various pedestrian loading conditions was implemented by finite element simulations regarding three influencing factors: impact heights, locations of impact and impact velocities. Finally, the injury thresholds associated with primary knee ligament injuries of pedestrians were defined with the dominant injury mechanisms: combined lateral bending and shearing effects. These thresholds are also well correlated with the previous criteria defined by isolated lower limb tests.