Abstract
The paper presented here concerns with the bumper system design optimization for legform impact. Not only lower leg impact but also vehicle to dummy collision were simulate to answer the question whether the optimized body structure for the sub-system impact is also optimal for real pedestrian impact. Parametric analysis of bumper system under lower leg impact was performed. Modifications in bumper system, which required minimum package space to meet lower leg impact limits were designed. Besides the bumper absorber, the spoiler stiffener was designed not only for keeping the bend angle and the share displacement under limit value, but also for tibia acceleration reduction in this study. It was proved that properly designed stiffness of the lower stiffener and its relative position to the rest of the bumper significantly influenced both distribution of legform impact energy absorbed by bumper itself and spoiler (lower stiffener) and tibia acceleration. The effect of design changes, leading to improvement in the lower leg impact, on the total kinematics and loading on the pedestrian was investigated. Vehicle-to-dummy collisions ware simulated to investigate the dummy responses to impact with all bumper modifications examined in previous stage. Based of simulation results, it was possible to conclude, that the optimization objective for the front panel defined as: the lower legform under limit plus reduction of package space were not in contrary to requirements on pedestrian kinematics to reduce its injury risk.
Keywords - Pedestrian protection, legform, bumper design, impact energy absorption, FEM simulation