Assessment of a Safe Bumper System Using a Pedestrian Lower Limb FE Model

Lower limb injuries are common result of car to pedestrian impacts. A reversible bumper system was developed to reduce the risk of such injuries. In order to improve the protective performance of the bumper system, it was necessary to investigate the efficiency of the bumper system at different impact conditions and design configurations.

In this study, the protective performance of the reversible bumper system was assessed by finite element (FE) modeling of lower limb impacts. The FE model of a production car front was developed and validated. The FE model of the reversible bumper system was then developed and replaced the original bumper in the car front model. A human lower limb FE model was used to evaluate the protective performance of the reversible bumper system. The effects of the bumper design parameters on protective performance were investigated by using the statistical method of factorial experiment design.

The injury responses of tibia acceleration, knee bending angle and shearing displacement were measured from the lower limb model. The injuries of knee ligament avulsions and long bone fractures were also obtained from impact simulations. By comparing the protective performance of the reversible bumper system at different impact conditions and design configurations, it was concluded that the bumper protective performance can be improved by reducing bumper stiffness; however, this performance can be impaired in the bumper deploying process by the speed of 2.5 m/s or greater.