Thoracic And Abdominal Injury Analysis Based On Finite Element Model Of A 6-Year-Old Pediatric Occupant

The traffic accidents data showed that thoracoabdominal injury was the second cause of child death after brain injury. Therefore, the profound understanding of pediatric thoracoabdominal injury mechanism is of great importance to improve the design of vehicle safety and reduce pediatric thoracoabdominal injury. Cadaver experiment is the most important way to investigate the thoracoabdominal injury mechanism, however, its application is restricted because of ethical reasons. With the development of the finite element theory and computer technology in recent years,pediatric chest and abdomen finite element (FE) models with real anatomy structures is another important method to investigate thoracoabdominal impact biomechanical responses and its injury mechanism.Based on CT data of a 6-year-old child, combined with reverse engineering and preprocessor module of finite element technology, FE models of soft tissues of thorax and abdomen, such as muscles, fat and skin tissues, were constructed. The whole FE model included the thoracic and lumbar spine, rib, rib cartilage, sternum, clavicle,scapula, intervertebral disc, diaphragm, trachea, blood vessels, oesophagus, heart,lung, stomach, liver, spleen, kidney and muscle, fat and skin tissue.The pediatric cadaver thorax and abdomen impact experiments were reconstructed using the developed thorax and abdomen FE model. Simulation results ,such as thoracic and abdominal impact force-displacement curve, the viscous criterion(VC) ,were calculated. The detailed FE model was validated by comparing the simulation results and the cadaver experiment results. The injuries of rib and internal organs, such as heart, were deeply analyzed using their plastic strain and the first principal strain, and the injuries predicted by simulation were in accordance with the cadaver results.Based on the validated thorax finite element (FE) model, the FE models with equivalent muscles was developed respectively, and the effect of muscle bio fidelity on thoracic injury was analyzed by reconstructing pediatric cadaver thorax impact experiments. The simulation results showed that the correlation coefficient between cadaver corridor and FE model with real muscles was greater than that between cadaver corridor and FE model with equivalent muscles. As a conclusion, FE models with real geometric muscles can accurately reflect the biomechanical response of thorax during the impact.Simulation experiments were performed using the 6-year-old finite element model to investigate the protection effects of child restraint system on pediatric thoracoabdominal injury. The results of the 6-year-old pediatric thoracoabdominal compression and internal organ injury showed that the forward-facing child safety seats could provide better protection for the 6-year-old child. However, the child should stop to use child safety seats when his shoulder is higher than the seat belt hole of child seat, because the spine will be oppressed by the stretch of safety belts due to rapid deceleration.Obese FE models with different Body Mass Index (BMIs) of 16.8kg/m2 and 18.4kg/m2 were constructed on the basis of verified child FE model, and the effect of obesity on pediatric occupant injury risk was investigated. The simulation results showed that subcutaneous adipose tissue was not like foam which can protect the internal organs,while the increasing fat made the injury of some internal organ more severe.