Finite Element Modeling Of Human Torso And Exploration On Blunt Injury Biomechanism

ObjectiveTo develop the human torso FE model by the virtopsy and3D reconstruction and the finite element methods, and to simulate the injury process of human torso by using the FE methods. The biomechanical response of the model was analyzed to explore the mechanisms of blunt rib cage and liver injuries. The injury process was illustrated by pictures, diagrams and animations to demonstrate the relationship among the force, deformation and damage. Thus provide a new and reliable method and visual evidence for injury investigation in forensic practices.MethodsMDCT images of human torso were obtained and used to develop a3D reconstruction and a finite element model of human torso with the help of finite element modeling software. After validation, the right hypochondrium area of the rib cage model was simulated to sustain frontal impacts by a blunt impactor with velocities of4m/s,6m/s and8m/s, and the distribution of stress and strain of the model was analyzed. Also right hypochondrium of the whole torso model was simulated to be punched by a fist from the frontal, lateral, and rear directions, and in each direction with velocities of4m/s,5m/s,6m/s,7m/s and8m/s. The biomechanical responses of the model were combined with an actual case to explore the mechanism of blunt liver injuries.ResultsA highly anatomically simulated finite element model of human torso consisting of rib cage, liver, thoracic and abdominal organs and soft tissues was developed based on CT scanning data of the victim, which possessed a fine element quality of above0.7. Biomechanical analysis showed that the thoracic cage revealed both local bending and overall deformation after the impact. Stress and strain arose from the initial impact area of the ribs, and then spread along the ribs to both sides, at last concentrated in the posterior side of the ribs and near the sternum. Impacts with velocities of6m/s and8m/s were predicted to cause rib fractures when strain of the ribs beyond the threshold values. Liver rupture was primarily caused by a direct strike of the ribs induced by blunt impact to the abdomen. Among three impact directions, a lateral impact was most likely to cause liver injury with a minimum punch speed of5m/s (the momentum was about2.447kg.m/s). Liver injuries could occur in isolation and were not accompanied by rib fractures due to different material characteristics and injury tolerance.ConclusionThe combination of MDCT and finite element method were capable of establish a highly simulated three-dimensional finite element model of human torso. And the established model could be applicable to analyze biomechanical responses of the different tissues of human torso under blunt forces, and to provide a new method for the forensic identification of human torso injury.