Development Of A Three-Year-Old Child Head Finite Element Model And Investigation Of Craniocerebral Injury Responses

The main content of injury biomechanics of child head is to investigate its injury mechanism and tolerance limit,which can provide theoretical support and biomechanical data for developing head protection device and safety system.In recent decades,using the head finite element(FE)model to reconstruct cadaver tests and simulate collision accidents is one of the most important methods to investigate the head injury biomechanics.However,factors,such as the biofidelity of child head model,material properties of craniocerebral tissue and boundary condition setup of simulation experiment,affect the accuracy of child head injury prediction by using head FE models to some extent.This work systematically summarizes the progress of child head FE models from the views of model meshing,element properties,model validation and model application.The detailed FE model of a 3-year-old child head was constructed based on investigation of the developed child head FE model.Deep brain structures,such as the white matter and gray matter of brain tissue,ventricle,hippocampus,diencephalon,and the other tissue,were extracted and created in the FE model.The child head FE model is one of the most detailed FE models nowadays.The developed 3-year-old child head FE model was validated by reconstructing the cadaver test of child head.Design of experiment(DOE)and analysis of variance(ANOVA)was adopted to investigate the effects of brain tissues mechanical parameters on impact responses of child head by using the validated FE model of 3-year-old child head.Statistical analysis results showed that elastic modulus of skull and viscoelastic mechanical parameters of brain tissue had statistically significant effects on impact responses of child head.The loading method that FE heads at different ages impacted with each other was firstly used in this work to obtain the same linear impact load.The head responses of children at different ages were investigated under same impact condition,and the responses were also used to evaluate whether the same HIC is reasonable to assess head injury for all age children in automobile safety regulations.Results showed that the HIC value of 3-year-old child was greater than that of 6-year-old child under the same linear impact loading condition,which indicated that a 3-year-old child head more likely suffered from head injury than a 6-year-old child.Therefore,the smaller HIC value for younger child was suggested in automobile safety regulations.Head rotation was simulated to investigate child head concussion injury critera by using child and adult FE models.Two brain injury predictors of CSDM and MPS was calculated according to simulation results,and the head injury risk curves for the two predictors with different severities were established.Because injury predictors of CSDM and MPS can only be calculated using FE models and cann't be measured in real accidents,the injury indicators of angular velocity and angular acceleration of head rotation which can be easily measure during the impact was firstly suggested for injury threshold to predict the child brain injury under the rotating load.The research can provide a new method to predict brain injury in practice.