快速高仿真人骨有限元几何建模—–基于Mimics、Geomagic及Ansys软件的应用

综合运用Mimics、Geomagic及Ansys软件, 探讨快速、高度仿真、具有通用性意义的不同类型人骨的有限元建模方法. 采集长骨(股骨)30例、不规则骨(胸椎)10例及扁骨(骨盆)10例的薄层CT扫描数据, 在Mimics中进行图像编辑及三维重建. 实验分设3组, 分别为传统方法组、改良方法组及快速建模组. 快速建模组由Geomagic进行模型网格简化, 在Mimics中进行体积恢复, 运用Ansys命令流进行快速网格划分, 在Mimics中赋予材料属性后进行最简单的有限元分析. 比较3组的建模时间、仿真程度, 并进行统计分析. 结果发现: (1)快速建模组具有建模时间少、仿真程度高及网格质量高等显著优势; 统计分析表明, 快速建模组与其他2组具有显著性差异. (2)在Geomagic中进行模型简化的主要参数“Target Edge Length”为2.0mm(规则骨), 1.5~ 1.8mm(不规则骨); 模型体积/简化网格数为1.50±0.92(股骨)、2.86±0.84(骨盆)、0.36±0.05(胸椎). (3)可以通过Geomagic处理后模型体积/原模型体积的立方根或者二者的回归函数来进行体积恢复. 研究结果表明, 基于逆向工程软件Geomagic的人骨有限元建模方法具有快速、高仿真、高成功率及通用性等优势, 推广价值较高.

Fast geometrical modeling of orthopedic structures with high efficiency and accuracy for finite element modeling: Based on integratedapplication of Mimics,Geomagic and Ansys

Through integrated application of Mimics, Geomagic and Ansys, the finite element modeling method of bones with fast and high simulation was investigated. CT scan data was collected from typical human bones which included 30 cases of long bones (femur), 10 cases of irregular bones (thoracic vertebra), and 10 cases of flat bones (pelvis). The image and three-dimensional reconstruction were edited in Mimics. The experiments were divided into three groups including traditional method, improved method and fast modeling method. In the fast modeling group, mesh was simplified in Geomagic and volume was restored in Mimics. Furthermore, meshing by command stream was analyzed in Ansys and assigned with material attributes in Mimics. The similarity between the three-dimensional model and the original model was evaluated, according to the 0 to 10 rating scale. The modeling time and similarity of the three groups were measured. The results show that the fast modeling group has the advantage of less modeling time, significantly higher similarity and mesh quality compared with traditional method and improved method group. The main parameter “Target Edge Length” of model simplification in Geomagic is 2.0 mm (regular bones) or 1.5-1.8 mm (irregular bones). The model volume/simplified meshes are 1.50±0.92 (femur), 2.86±0.84 (pelvis), 0.36±0.05 (thoracic vertebra). The model volume can be restored by the cube root of the volume ratio before and after Geomagic processing, or by the regression function. The fast high simulation finite element modeling method is more efficient and produces higher meshing quality