Impact Injury Analysis Based On Thorax FE Model Of A 6-Year-Old Child Occupant

In the traffic accident, children are vulnerable groups, chest injury is the one of more serious injury parts. With the increasing of the use rate of child safety seat, in order to provide theoretical guidance for optimization of child safety seat, it is very important to analyze chest injury and study its injury mechanisms in different collision. But the existing research mainly takes adults as the research object. The model, especially the finite element model of child occupant’s thorax is rare in the world. So developing the finite element model of child occupant thorax with high biological simulation degree is necessary.Because of the existing technical conditions, the data obtained is only the lying posture model, so the study established the child sitting-posture model based the existing 6-year-old child lying-posture model which was constructed by Tianjin University of Science& Technology. And the study used the tracing point method to draw the spinal curve by referring to the evaluation rules of the child restraint system and relevant laws and regulations. The 6-year-old child occupant spinal curve that accorded with anatomical structure was obtained by rotating, scaling and translating. Based on the curve,6-year-old child thorax geometric model was obtained by adjusting thoracic tissues such as vertebral column, rib, sternum, muscle and so on.In order to obtain the finite element model of child occupant’s thorax, mesh the model and connect related parts using Hypermesh and Truegrid. Then assign the model related material parameters, contact and loads. Reconstruct the cadaver experiment using Ls-dyna, the model is available and the method is feasible by comparing the Interface force-Deflection and the scaling result of cadaver experiments.Based on the validated model, the study got different values of thoracic compression as changing the velocities of impactor. When impacting the thorax with higher velocity, the value of thoracic compression standard becomes grater and the probability of the thoracic serious injury is increasing in the front collision. And the probability that ribs fractures is increasing in the side collision. Ribs are easily fractured in the maximal curvature or stress in different impacting position in transverse and longitudinal direction in side impact.Comparing the result of simulation in front and side collision, the soft tissues more easily are caused serious injury in the front collision. And the ribs more easily are caused to fracture in side collision.The analysis of injury mechanism of the child occupant’s thorax in different collision by developing the finite element model of 6-year-old child occupant’s thorax can provide theoretical guidance for optimization of child safety seat and design of more secure devices that protect children. Also it is important to enact the law about how to protect children.