The Injury Study Of A Three-year-old Child Occupant Pelvis In Side Impact

The rapid development of automobile industry has changed the way people travelling and it makes,traffic accident injury as one of the important factors that threaten children's life.Pelvis is one of the most easily injured boby parts of children.Therefore,to investigate the biomechanical response of children's pelvic injury,not only practically necessary but also is novel academically.With the advanced computer technology and the wide application of the finite element method,developing a finite element model of children's pelvis with human-liked anatomical feature provides reliable method for the study of children's pelvic impact biomechanical response.This thesis developed a detailed three-year-old child's pelvis finite element based on medical CT scan data of a three-year-old child,Model geometric data was obtained through CT scan image analysis.Model meshes were generated in combining with reverse engineering and finite element techniques.This model includes skin,fat,muscle and ligament soft tissues and it is validated by reconstructing the pelvic side impact test of children's cadaver.The validated three-year-old child and adult pelvic finite element models were used to investigate the different responses under the influence of different material properties and geometrical structrure for the same loading condition.Results show that stress of children's pelvis is greater than that of adult's pelvis,and maximum strain of children's pelvis is located at the sacroiliac joint under the same impact condition.However,shear stress of adult's pelvis pubic symphysis is greater than that of the children.The influences of cortical bone thickness and impact velocity on children's pelvis impact response were analyzed with the three-year-old children's pelvis finite element model.According to the correlation analysis of pelvic injury,results showed that the thickness of compact bone is sensitive to the contact force,stress and maximum plastic strain.The smaller the thickness of pelvic cortical bone is,the more easily the pelvis is getting damaged.The impact velocity has a significant impact on the response of stress and strain,the contact force,deformation and viscosity index.These results can be used for children's pelvic injury threshold study in a more accurate way.The final part of this thesis is to study the effectiveness of the child safety seat restraint system in side pole impact and mobile deformable barrier side impact.Two design schemes were established to analyze the injury influence of child safety seat restraint system on children's pelvis:(1)without restraint system;(2)with child safety seat.Simulations show that children's pelvic Y-shaped cartilage absorbs most energy and is the first to get damage in side pole impact.The child safety seat restraint system has a certain protective effect for children in the mobile deformable barrier side impact,but children's pelvic part is more seriously getting damaged.