Study On Reconstructing Traffic Injury Manners And Mechanisms By Finite Element Approach

Objective To develop the human lower extremity FE model by the virtopsy3D reconstruction and hexahedron mesh generation methods, and to simulate the injury process of lower extremity by explicit dynamic FE methods. Explore the primary pelvis, femur, lower extremity injury mechanisms and manners by the forms of mechanics index trendencies, pictures and animations from the view of force-deformation-injury. Improve the quality and accuracy of forensic investigation by the FE reconstruction and eventually provide new thoughts, reliable technological ways and visualization biomechanical evidence for the forensic practices.Methods Based on the external skin and internal organ injury detail scan data from MSCT and MRI, reconstruct the3D geometry of injury area by the combination utilization of virtopsy3D reconstruction and FE modelling methods, and determine the force postion, direction and degree combined with the forensic investigation results. Develop the FE models of human pelvis, femur and lower extremity by using Mimics, Ansys and ICEM software, and verify the validity of models by comparisons between simulation results and literature test data. In the real case basis, load different initial conditions to simulate the possible accident scenes by using explicit dynamic FE system Ls-Dyna and Ls-PrePost, and work out the injury biomechanical response in terms of distributions and trendencies of stress and strain. And further research on the injury mechanism the forms of mechanics index trendencies, pictures and animations.Results Based on CT scanning data of the victim, the real human geometry-based FE model of pelvis, femur and lower extremity were developed through a series of3D reconstruction, grid mesh, material property attribution and validity verification. By loading different initial injury conditions, the FE simulation results truly represented the stress distributions of pelvis under vertical gravity force and various magnitudes of lateral forces. The FE model simulated the characteristic segmental long bone fractures by wheel running over, compared with the bumper fracture of femur and tibia by direct collision. Explored the different injury features of knee under different velocities, directions and collision sites and found that the features of direct impact bone fracture is similar to the realistic injuries. Conclusion The combination utilization of3D Virtopsy and FE modeling and analysis methods can truly reconstruct the human injury response processes, accurately analyze the injury manners and conclude the injury mechanism. It does also make the forensic experts more effectively to investigate the human injury and provide new biomechanical evidence to the court.