Study On Head And Neck Injury Mechanism Based On A Six-year-old Child Whole Body Finite Element Model

Head and neck injury is the most common type of injury in traffic accidents and one of the main cause of death of occupants.In recent decades,great progress has been made in the study of adult injury mechanism in accidents.and constantly through optimizing and adjusting the vehicle body structure,passive safety devices to reduce human's head and neck injury,but the research on children injury is very limited.From the point of physiological structure characteristics,Children are not miniaturized adults,and the structure of skeleton and soft tissue is not fully developed,there are still some differences in anatomical structure compared with adults,Therefore,the damage mechanism and data are not simply a scaling relationship.The whole body finite element model of six-year-old child used in this study is a biomechanical computational model with high biofidelity based on the characteristics of children's physiological structure,which can restore the injury process of children in accidents to the maximum extent.It is of great significance to study the mechanism of injury and improve child injury protection.In order to explore the effect of restraint system misuse on the injury of head and neck for rear occupant of 6-year-old children in frontal impact crashes,the head and neck injuries of the child's finite element model under correct and incorrect use of restraint system were compared and analyzed.The results indicate that the force and moment of neck is minimum when use of booster seat merely,but the maximum intracranial pressure,maximum Von-misses and maximum principal strain is larger than their damage threshold and will cause fatal brain damage in children's head.The only use of adult safety belt will cause more serious damage in children's neck with larger force and moment.Two misuse ways of restraint system aggravated the injuries of head and neck of 6-year-old child.Proper use of restraint system can provide the best protective effect for 6-year-old child's head and neck.In this study,the 6-year-old child whole body finite element model was placed in forward facing child seat and booster respectively,and the protective effects of the two restraint systems on children in frontal collision at different speeds were compared.The results indicate that:When the collision speed is low,there was no significant difference in the damage indexes of intracranial pressure,Von Mises stress,shear stress,neck force,and chest and abdomen compression between the two restraint systems.But with the increase of the collision speed,the protective effect of child restraint system to the children is better than booster.This model was used to carry out side impact experiments.By filling the energy-absorbing foam on the head cushion of the child safety seat wing structure and changing its parameters to studied the protective effect of energy-absorbing foam on children's head.Analysis shows that the foam in the child safety seat can effectively reduce the head injury in the side impact,and the protective effect of the Polyurethane foam is better than that of the Expanded Polystyrene foam.Further studies also show that when designing energy absorbing foam,if it will not affect the comfort of children,the foam can be designed as thick as possible;If the foam will not touch the bottom when collision,its elastic modulus can be designed as smaller as possible.In order to study the mechanism of head and neck injury in children,and to explore the protective effect of restraint system on head and neck injury of children,a 6-year-old child whole body finite element model was used to simulate the frontal and lateral impact tests,The research results have important theoretical significance and application value for further understanding the mechanism of head and neck injury in children,designing and developing better restraint system for children.