金属生物材料支架的微结构拓扑优化设计及选区激光熔化制造

摘要

The precise design and fabrication of biomaterial scaffolds is necessary to provide a systematic study for bone tissue engineering.Biomaterial scaffolds should have sufficient stiffness and large porosity.These two goals generally contradict since larger porosity results in lower mechanical properties.To seek the microstructure of maximum stiffness with the constraint of volume fraction by topology optimization method,algorithms and programs were built to obtain 2D and 3D optimized microstructure and then they were transferred to CAD models of STL format.Ti scaffolds with 30％ volume fraction were fabricated using a selective laser melting (SLM) technology.The architecture and pore shape in the metallic biomaterial scaffolds were relatively precise reproduced and the minimum mean pore size was 231 μm.The accurate fabrication of intricate microstructure has verified that the SLM process is suitable for fabrication of metallic biomaterial scaffolds.%生物材料支架的精确设计和制造是骨组织工程系统研究的基础.生物材料支架应该同时满足大孔隙率和与骨组织匹配的力学性能要求.这两个目标相互制约,大的孔隙率会降低其力学性能.利用拓扑优化的方法,在体积分数的约束下,寻求刚度最大的最优材料分布微结构.建立算法,得到了不同体积分数的2D和3D最优微结构,并提取3D拓扑优化的结果,然后将其转化为STL格式的CAD模型文件.微结构在三维方向整列成支架结构,通过选区激光熔化方法制造30％(体积分数)的Ti支架样品.从SEM图像看出,支架样品的结构和孔径与CAD模型基本一致,500 μm微结构单元的平均孔径为231 μm.复杂形状金属生物材料支架的精确制造证实了选区激光熔化技术在金属生物医学材料制造中的可行性.