Impact Overlaps on Occupant Lower Limb Injuries under Car Frontal Crash

The lower extremity is one of the most difficult parts to protect in a car collision. The purpose of this paper is to determine the injury characteristics of the lower extremities under frontal collisions with different overlaps. The test device for human occupant restraint (THOR) 50th finite element model was used to conduct three collision simulations based on the actual load environment. Then the kinematic responses of the lower extremity like axial force/moment of the femur, and tibial index in frontal collision were compared to analyse the relationship between lower extremity injury and collision overlaps. Results show that the kinematics of the occupant's lower limbs is sensitive to collision overlap rates. As the collision overlap increased, the amplitude of lower limb displacement would decrease. The most serious femoral injury occurred in the 25 % overlap frontal collision. Especially in the left middle femur, the peak axial force reaches 3.2 kN and the peak bending moment reaches 108 Nm. In a full-frontal collision, the risk of femoral injury is serious, which may relate the great vehicle acceleration. The tibia index is not significantly different in frontal collisions with overlap rates. This study can provide a reference for the study of lower extremity injury mechanism during frontal collision.