Design of “Lower Stiffener” for Controlling Pedestrian Lower Leg Injuries

Pedestrian protection is becoming an increasingly important aspect in vehicle safety development across the globe. The two primary focus areas are protection to the head and the lower leg of the pedestrian in impacts with motor vehicles. This paper discusses the protection aspects for lower leg in pedestrian impacts.

The pedestrian lower leg injuries are measured in the form of deceleration; bend angle and knee shear as stated in regulations. Careful study indicates that a minimum of two load paths namely the upper load path (to support the femur) and the lower load path (to support tibia) are required to control the above stated injuries. Careful optimization is required to balance the stiffness on both the load paths. This paper further focuses on the component optimization to achieve necessary stiffness along the lower load path for injury control. One of the lower load path usually consists of the bumper, “lower stiffener” and its fixing system. Several iteration were carried out using CAE followed by physical tests with due considerations for design, performance, packaging and manufacturing constraints. The load path was optimized using correlated model and design was signed off successfully through full scale pedestrian lower legform tests