OBJECTIVETo explore the relationship between the collision parameters of vehicle and the pedestrian thorax injury by establishing the chest simulation models in car-pedestrian collision at different velocities and angles.

METHODS87 cases of vehicle-to-pedestrian accidents, with detailed injury information and determined vehicle impact parameters, were included. The severity of injury was scaled in line with the Abbreviated Injury Scale (AIS). The chest biomechanical response parameters and change characteristics were obtained by using Hyperworks and LS-DYNA computing. Simulation analysis was applied to compare the characteristics of injuries.

RESULTSWhen impact velocities at 25, 40 and 55 km/h, respectively, 1) the maximum values of thorax velocity criterion (VC) were for 0.29, 0.83 and 2.58 m/s; and at the same collision velocity, the thorax VC from the impact on pedestrian's front was successively greater than on his back and on his side; 2) the maximum values of peak stress on ribs were 154, 177 and 209 MPa; and at the same velocity, peak stress values on ribs from the impact on pedestrian's side were greater than on his front and his back.

CONCLUSIONThere is a positive correlation between the severity and risk of thorax injury and the collision velocity and angle of car-thorax crashes. At the same velocity, it is of greater damage risk when the soft tissue of thorax under a front impact; and there is also a greater risk of ribs fracture under a side impact of the thorax. This result is of vital significance for diagnosis and protection of thorax collision injuries.