Diagnosing Vehicle Aggressiveness for Pedestrian Leg Impact and Development of Efficient Front End Energy Management Systems 2010-01-1168

Worldwide involvement in Global Technical Regulation (GTR) discussion shows the increasing importance of pedestrian safety as a global concern. Vehicle front styling plays an important role in vehicle to pedestrian impact. Front styling can change the pedestrian kinematics and injury levels during an impact. Key elements of bumper front are Fascia, Upper & Lower Grille, Hood, spoiler or undertray, bumper beam and height of these components from ground level, determine the vehicle aggressiveness for pedestrian safety.

This paper presents an approach to diagnose the vehicle front aggressiveness for pedestrian leg impact. Eight different vehicle bumper front configurations from ‘minis’ to ‘sedans’ are studied for lower leg impact cases, to understand the bumper stiffness profile (stiffness in upper, middle and lower load path). Numerical models are derived to relate the knee deceleration; knee bending and tibia shear with bumper stiffness profile, through extensive Computer Aided Engineering (CAE) and Design of Experiments (DOE) based numerical studies. The desirable ‘vehicle front stiffness profiles’ are identified for development of efficient pedestrian countermeasures and different front-end energy management solutions are proposed to achieve the same, using thermoplastic materials, commonly used material to design energy absorbers for pedestrian safety.