Abstract:

A design method of vehicle front-end structure stiffness was proposed based on a multi-body
dynamics model to improve pedestrian lower leg protection. The model was established in Madymo, based on
the crash tests of the leg form impact to car and a FE (finite element) model of the vehicle front-end structure,
according to the geometry and stiffness parameters which were obtained by the finite element analysis on
the collision area. An optimal design was completed by the global response surface method (GRSM). The
optimal objective was the mean square evaluation (MSE) of normalization of three injury criterion (the tibia peak
acceleration, knee bending angle, knee shear displacement) with 4 design variables including the yield forces
and the maximum deformations for the bumper and the auxiliary bumper. The results show that the objective
reduces by 73.9%, the tibia peak acceleration decrease by 50.3% with the knee bending angle decreasing
48.9%. Therefore, the optimization of the vehicle front-end structure stiffness improves the performance of
pedestrian leg protection.

Key words: pedestrian protection, multi-body model, automobile, design of stiffness, optimization