6岁儿童头部有限元模型的构建与验证

Development and Validation of a 6-Year-Old Child Finite Element Head Model

借助6岁儿童医用头部CT扫描图片,通过图像分析处理,提取几何参数,重构生成三维几何模型。对几何模型进行有限元前处理,构建了一个6岁儿童头部有限元模型。模型中包含颅骨、骨缝、脑脊液、大脑、小脑、脑干、脑室等各个器官,共有44 886个节点,11 675个壳单元,37 482个六面体单元。.各器官材料属性采用来自参考文献的数据。仿真分析计算中,力加载时窗为11 ms时,模型的CPU计算时长低于1 h。采用Nahum尸体实验数据与仿真结果进行对比。仿真分析结果显示:成人头部撞击时撞击压与对撞压的形成规律同样适用于儿童头部碰撞。在7 900 N力作用下,尸体头部撞击侧最大压应力为140 kPa,对撞侧最大压应力为-60 kPa,而儿童头部的值分别为220.2 kPa和-135.2 kPa;在HIC值均为775的作用下,成人头部撞击侧和对撞侧最大压应力分别为140 kPa和-60 kPa,而儿童头部的值分别为160 kPa和-89 kPa。这表明,在相同作用力或HIC值下与成人相比,儿童头部更容易受到损伤。

In this work a three-dimensional finite element （FE） human head model of a six-year old child was developed. Geometrical data of the FE head model were extracted from a set of medical CT scan images of a six- year old child. Finite element meshes were created from the geometric data through the FE preprocessor. The child head model included 44 886 nodes, 11 675 shell elements and 37 482 solid elements. The model included skulls, sutures, CSF, cerebrum, cerebellum, and brainstem. Material properties of the child head model were obtained from biomechanical literature. It took less than one hour CPU time for an 11 ms analysis in a workstation. Since there were no experimental test data of child head impact in the literature, Nahum＇ s data were used for impact response comparison. Simulation results showed that the development of coup-contrecoup pressure during impact is suitable to be used in the analysis for the child head. The value of coup and contra-coup stresses were respectively 140 kPa and - 60 kPa on the force of 7900 N and HIC value of 775 in the cadaver experiment. Under the same impact condition, the values of coup and contra-coup pressure were 220.2 kPa and -135.2 kPa and 160 kPa and -89 kPa, respectively. These data showed that child head was more vulnerable to the injury than adult head.