Thoracoabdominal injury analysis of a 6-year-old pedestrian finite element model in vehicle-pedestrian collisions

A holistic human body finite element model of a 6-year-old pedestrian was completed by integrating the skin, soft tissues and joint ligaments, based on the component models of a 6-year-old child. The complete model was verified by comparing to available cadaveric test data. Then it was used to simulate collisions of midsize car/SUV-paediatric pedestrian at different collision speeds, in order to study the effects of collision speed, and vehicle type on kinematic/biomechanical responses of paediatric chest and abdomen, and to predict the injuries of bones and internal organs according to compression/viscous criterion and strain. Simulation results showed that the number of rib fractures increased with the increase of collision speed in collision simulations of midsize car-paediatric pedestrian, but no rib fracture appeared in simulations of SUV-paediatric pedestrian impact. Maximum values of chest/abdomen/thigh impact forces, maximum deformation/VCmax of paediatric chest and abdomen, and maximum first principal strain of internal organs were proportional to collision speed. Predicted paediatric chest and abdominal injuries, obtained from the midsize car-pedestrian simulations, were found to be consistent when compression/viscous criterion and first principal strain were used as a yardstick for injury assessment. Additionally, compression/viscous criteria had some limitations on the prediction of rib fracture in SUV-pedestrian collision simulations.