基于CT图像的长管骨有限元材料属性研究及实验验证

目的探讨经酒精处理的新鲜人体长管骨个性化材料属性定义的方法,以及骨骼材料数目对有限元结果的影响。方法利用断层扫描CT图片,在Mimics中建立股骨干三维实体模型,然后导入Hypermesh中分割成皮质骨、松质骨以及骨髓;根据相关经验公式分别赋于皮质骨和松质骨的材料参数,设置5组材料数目的不同仿真组;在Abaqus中进行线弹性阶段的压缩实验仿真,并进行体外验证实验。结果端部位移在0～1 mm时,松质骨材料数目为1种,皮质骨材料数目大于10种的整体力-位移有限元仿真结果与实测数据平均相对误差在10%左右;骨干的测量点变形量的有限元结果与实测数据相对误差为14.6%。在小位移下0～0.5 mm时1,种皮质骨材料的整体力-位移的仿真结果与实测数据误差为2.83%。结论 (1)利用CT图片灰度值,可以精确定义骨骼各成份的材料属性;(2)皮质骨材料数目设定对有限元仿真结果影响较大,将皮质骨设定10种即可满足有限元分析需要;(3)小变形时,1种材料的皮质骨就能满足分析要求。

Study and verification test on finite element materials properties of the long bone based on CT images

Objective To discuss the method for defining personalized materials properties of the fresh human long bone with alcohol treatment and the effect from the number of bone materials on finite element results.Methods Based on images from CT scans,a three-dimensional solid model of the long bone was established in Mimics,which was then classified into the cortical bone,cancellous bone and marrow in Hypermesh.Based on relevant empirical formulas,material parameters of the cortical bone and cancellous bone were given,respectively,and 5 finite element analysis(FEA) models with different numbers of materials were set up.The simulation for linear elasticity of the compression was carried out in Abaqus and the results were validated by in vitro verification test.Results Under the end displacement ranging from 0 to 1 mm,the average relative error between the simulation results and the experimental data for holistic force-displacement was about 10%,when the materials number was defined as 1 kind of the cancellous bone and over 10 kinds of the cortical bone.And the average relative error between the simulation results and the experimental data for the deformation of the measurement points was 14.6%.The error of holistic force-displacement for 1 kind of the cortical bone was 2.83% when the end displacement ranged from 0 to 0.5 mm.Conclusions(1) Using the gray value of CT scans,materials properties of the main component of the bone could be defined accurately.(2) The simulation result was greatly affected by the material number of the cortical bone,and defining 10 kinds of the cortical bone could satisfy the FEA need.(3) The FEA model with 1 kind of the cortical bone also could satisfy the need of analysis under small deformation.