| Traumatic Brain Injury(TBI)is a common and serious public health problem worldwide.Closed head impact injury is the most common type of traumatic brain injury in traffic accidents,with millions of deaths per year.personnel resulting in casualties.The research on the biomechanics of craniocerebral injury can analyze the mechanical response of the human head when it is subjected to external loads,and understand the quantitative relationship between the degree of craniocerebral injury and the load conditions,so as to provide theoretical support for improving vehicle collision safety regulations and improving the safety performance of automobiles.Reduce the casualty rate of people in traffic accidents.However,due to ethical constraints,the study of human craniocerebral injury has certain limitations,and the use of animal finite element models combined with animal experiments to study the biomechanics of craniocerebral injury has become one of the alternatives.In this paper,a finite element model of the rat head was established and verified according to the literature and experiments.The verified model was used to carry out research on the influencing factors of closed craniocerebral injury.The specific research contents are as follows:using medical image extraction software to analyze The computerized tomography and nuclear magnetic resonance image data of the head were extracted from the three-dimensional point cloud,the geometric model of the rat head was established by using the reverse engineering software,and the rat head was meshed by the general finite element pre-processing software;through the reference The literature is used for material definition and brain-brain contact interface setting.The model includes the head,neck and body boundaries composed of skin,skull,and spine,as well as 27 brain anatomical structures including cortex,cerebellum,ventricles,brainstem,olfactory bulb,corpus callosum,hippocampus,thalamus,hypothalamus,and internal capsule.Referring to the relevant literature on dynamic cortical displacement test,cranial relative displacement test,and control cortical impact test,the corresponding simulation conditions were established;the closed head impact test was carried out,and the corresponding simulation conditions were established,and the finite element simulation results were compared with the experimental results.The results are compared,and the finite element model is verified qualitatively and quantitatively.The finite element simulation results are in good agreement with the experimental results,which proves the reliability of the finite element model.Orthogonal experimental design and analysis of variance were used to study the influencing factors of closed head impact injury in rats.Taking impact speed,rat weight and helmet material as test factors,a three-factor three-level orthogonal table was constructed to arrange finite element simulation,and the maximum principal strain and equivalent stress of cerebral cortex and skull were taken as test indicators,and determined by multi-factor analysis of variance.The impact of factors on the indicators clarifies the primary and secondary sequence of factors that affect the degree of craniocerebral injury.The results showed that the important factors affecting the maximum principal strain and equivalent stress of the cerebral cortex and the maximum principal strain and equivalent stress of the skull were impact velocity and weight,respectively,while the material of the helmet only had a significant impact on the equivalent stress.Therefore,the choice of helmet material may not affect brain tissue damage,but it will affect skull fractures.This study developed and validated a closed head impact injury model in rats,and studied the influencing factors of closed head impact injury from a mechanical point of view,which has reference significance for the study of closed head impact injury. |
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