Xu Shubo, Zhang Sen, Ren Guocheng, Pan Yuefei, Li Jianing
School of Materials Science and Engineering, Shandong Jianzhu University, Jinan 250101, China.
State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
Materials (Basel). 2022 Aug 26;15(17):5896. doi: 10.3390/ma15175896.
In the implantation of porous bone scaffolds, good mechanical properties of the scaffold are a prerequisite for the long-term functionality of the implanted scaffolds, which varies according to the structure and the forming process. In this study, the influence of the forming parameters and structure of the Selective Laser Melting (SLM) process on the mechanical properties of 316L stainless steel bone scaffolds was investigated using finite element simulation combined with experimental methods. The mechanism of the influence of the process parameters and structure on the mechanical properties of bone scaffolds was summarized using static compression finite element numerical simulations, compression experiments, hydrodynamic simulations, forming numerical simulations and SLM forming experiments. The results show that the magnitude of residual stress and the distribution of defects under different process parameters had a strong influence on the microstructure and properties of the scaffold, and the residual stress of the Body-Centered Cube (BCC) structure formed at an energy density of 41.7 J/mm was significantly reduced, with less surface spheroidization and fewer cracks on the melt pool surface. The smallest grain size of 321 nm was obtained at an energy density of 77.4 J/mm, while in terms of mechanical properties, the optimization of the structure resulted in an 8.3% increase in yield strength and a reduction in stress concentration. The predictions of stress, deformation, and forming quality during construction with different process parameters, achieved using finite element analysis, are basically in agreement with the experimental results, indicating that the best process parameters for forming BCC structural supports were determined by using finite element simulation combined with experiments; moreover, the distribution and evolution of residual stresses and defects under different process parameters for constructing BCC structures were obtained.
在多孔骨支架的植入过程中，支架良好的力学性能是植入支架长期发挥功能的前提条件，其力学性能会因结构和成型工艺的不同而有所差异。在本研究中，采用有限元模拟与实验方法相结合的方式，研究了选择性激光熔化（SLM）工艺的成型参数和结构对316L不锈钢骨支架力学性能的影响。通过静态压缩有限元数值模拟、压缩实验、流体动力学模拟、成型数值模拟和SLM成型实验，总结了工艺参数和结构对骨支架力学性能的影响机制。结果表明，不同工艺参数下的残余应力大小和缺陷分布对支架的微观结构和性能有很大影响，在能量密度为41.7 J/mm时形成的体心立方（BCC）结构的残余应力显著降低，熔池表面的球化现象减少，裂纹也较少。在能量密度为77.4 J/mm时获得了最小晶粒尺寸321 nm，而在力学性能方面，结构的优化使屈服强度提高了8.3%，应力集中降低。利用有限元分析对不同工艺参数施工过程中的应力、变形和成型质量进行的预测，与实验结果基本一致，表明采用有限元模拟与实验相结合的方法确定了成型BCC结构支撑的最佳工艺参数；此外，还获得了构建BCC结构时不同工艺参数下残余应力和缺陷的分布及演变情况。
