后牙复合树脂粘接桥三维有限元建模方案研究与分析

建模和网格划分是粘接桥生物力学分析的难点.本文以基于STL数据的网格实体建模代替传统的曲面实体建模,提高了模型的几何相似性;重建三角面片间的拓扑关系,便于了模型的更改及布尔运算;牙周组织与纤维的正向设计及其合理简化,降低了工作量,减少了网格数量;基于STL数据拆分法的有限元网格划分,提高了单元质量.通过有限元计算取得了与理论推导和临床观察相一致的结果,证明了建模方法的有效性.

复合树脂粘结桥支架优化设计研究

以基于STL的网格实体建模方法,设计了修复体、基牙、牙周膜、骨皮质,骨松质和牙槽骨的三维几何模型.借助有限元分析,将力学模型简化为弯扭变形,确定了初步支架设计方案.同时通过施加真实口腔载荷,对支架结构进行了进一步的验证和优化,得到基于传统支架的改良设计方案Ⅱ-M和创新支架设计方案Ⅲ-M.计算表明较纯树脂粘接桥,对危险域里的应力值,方案Ⅱ-M能平均降低22.50%,方案Ⅲ-M则可达到37.80%.证明优化后的支架加强效果明显,对修复体能起到很好的保护作用.

Objective:To analysis through the mouth atlanto-axial vertebral anterior plate fixation in finite element for the development of the segmental anterior fixation surgery and to provide the reference of inner plant im-provement. Methods:One case, male, 36 years old, 64 kg weight was randomly selected from January 2014 to our hospital to check no-skull - atlanto-axial vertebral disease . It was scanned by 0. 625 mm thin layer, Image data were rebuilted in the Mimics 16. 01 software, Pro/ENGINEER 4. 0 software was used to rebuilt atlanto-axial vertebral anterior plate, After reconstruction of steel screw 3 d model according to the classic through the mouth , the model was imported into Mimics 16. 01 and the model surface was meshed and material was assigned, The mod-el was forced 80 N vertical loading, the surface was applied 15 nm torque, to simulat three motion state example, forward bends, stretch, side-bending, The stress and deformation of screw and rod were measured. Results: At-lanto-axial vertebral three-dimensional reconstruction model were divided into 14 514 individual grid, 7 257 nodes, the model was loaded, The stress of upper screw root in bend was biggest (62. 34 ±5. 52) Mpa (F=73. 23, P<0. 05, the difference was statistically significant). A screw of the root and the top, lateral stress was the largest, respectively were (78. 42 ± 5. 5. 14) Mpa (F=112. 32, P<0. 05);(95. 48 ± 7. 12 Mpa (F=62. 32, P<0. 05), the difference was statistical significance; Under three different motion state and a screw root stress, Upper screw root stress in bending forward was greater than the lower (forward bends, stretch and lateral bending state , t value were 12. 2, 9. 23, 22. 98, P<0. 05, differences were statistically significant), and in the lateral current screw root stress was greater than the upper; In the same movement state, the top was greater than the root, the differences were statistically significant (forward bends, stretch and lateral bending state after t value were 23. 14, 22. 01, 8. 13, P<0. 05). Conclusions: Through the mouth atlanto-axial vertebra fixed system stress distribution wad more reasonable, could withstand normal atlanto-axial after vertebral motion bearing stress, but the postoperative patients should reduce the proneness and lateral movement, and to the risk of fatigue fracture fixation system.

有限元分析在足部生物力学研究中的应用现状

1943年Courantz首先提出有限元分析(finite element analysis,FEA)的概念,其基本思想是用较简单的问题代替复杂问题然后求解.初FEA主要应用于飞机结构的静力和动力学特性分析.

Mimics V10.0软件STL模块与FEA模块在医学三维重建中的关系

目的 就STL模块与FEA模块在膝关节三维重建中的关系进行探讨,以便用Mimics V10.0软件获得更好的有限元分析预处理文件.方法 利用GE Lightspeed 16排螺旋CT的薄层扫描技术,基于1.25 mm 层厚,85 层人体膝关节的连续断层图像,Mimics 直接读入Dicom 格式原始图像,运用阈值选取技术、三维区域增长技术、空洞填充技术,去除冗余数据,三维重建后获得左膝关节STL三维实体模型,再经面网格优化后的模型可保存为后缀名是.lis 的Ansys有限元分析预处理文件,能直接导入Ansys 有限元分析软件生成三维有限元模型.结果 获得了图像质量更好的左膝关节FEA预处理模型,经面网格优化后的FEA预处理文件可直接导入Ansys有限元软件,进一步行运动生物力学分析.结论 Mimics 软件中FEA模块的面网格优化作用使STL三维模型的图像质量进一步提高,为后续的人体骨骼系统运动生物力学有限元分析的开展提供了可能.