关键词: 行人—车辆碰撞, 行人保护, 腿部, 有限元, 前保险杠, 泡沫材料, 车体前端造型

Abstract:  In pedestrian-car impact, front bumper materials, the vehicle sculpt, package and layout play a key role in pedestrian
leg protection. The stress and injury mechanism of the leg was analyzed and the test procedure specified in Euro NCAP (New
Car Assessment Programme) was simulated using large-scale nonlinear dynamic finite element program LS-DYNA 3D. The FE
(Finite Element) model was validated by comparing CAE (Computer Aided Engineering) and test results. The influence of foam
on the tibia acceleration, bending angle and shearing distance of the lower leg form was investigated by altering the x-direction
thickness, density, and z-direction mounting position of the foam. The influence of parameters on the sum of axis forces and bending
moment of the upper leg form was investigated by altering the bonnet lead edge (BLE) height, bumper lead, stiffness of hood and
x-direction mounting position of upper radiator beam. The results indicate that the stiffness property of EPP foam is more beneficial
for pedestrian protection among three types of foam (EPP, STRAND, PU). When the x-direction thickness, density, and z-direction
mounting position of the foam are changed, the trend of the the tibia acceleration is complex without clear pattern, while the trend of
the bending angle and shear distance are fairly constant and monotonic. The hood stiffness is less important to the upper leg injury,
while the other factors have significant effects.

Key words: pedestrian-car impact, pedestrian protection, leg, finite element, front bumper, foam material, vehicle front sculpt