State Key Lab of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
State Key Lab of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
J Mech Behav Biomed Mater. 2018 Apr;80:119-127. doi: 10.1016/j.jmbbm.2018.01.013. Epub 2018 Jan 12.
A significant requirement for a bone implant is to replicate the functional gradient across the bone to mimic the localization change in stiffness. In this work, continuous functionally graded porous scaffolds (FGPSs) based on the Schwartz diamond unit cell with a wide range of graded volume fraction were manufactured by selective laser melting (SLM). The micro-topology, strut dimension characterization and effect of graded volume fraction on the mechanical properties of SLM-processed FGPSs were systematically investigated. The micro-topology observations indicate that diamond FGPSs with a wide range of graded volume fraction from 7.97% to 19.99% were fabricated without any defects, showing a good geometric reproduction of the original designs. The dimensional characterization demonstrates the capability of SLM in manufacturing titanium diamond FGPSs with the strut size of 483-905µm. The elastic modulus and yield strength of the titanium diamond FGPSs can be tailored in the range of 0.28-0.59GPa and 3.79-17.75MPa respectively by adjusting the graded volume fraction, which are comparable to those of the cancellous bone. The mathematical relationship between the graded porosity and compression properties of a FGPS was revealed. Furthermore, two equations based on the Gibson and Ashby model have been established to predict the modulus and yield strength of SLM-processed diamond FGPSs. Compared to homogeneous diamond porous scaffolds, FGPSs provide a wide range of mutative pore size and porosity, which are potential to be tailored to optimize the pore space for bone tissue growth. The findings provide a basis of new methodologies to design and manufacture superior graded scaffolds for bone implant applications.
对于骨植入物来说，一个重要的要求是复制跨越骨骼的功能梯度，以模拟刚度的定位变化。在这项工作中，通过选择性激光熔化（SLM）制造了基于 Schwartz 菱形单元的具有广泛梯度体积分数的连续功能梯度多孔支架（FGPS）。系统研究了微拓扑、支柱尺寸特征以及梯度体积分数对 SLM 加工 FGPS 力学性能的影响。微拓扑观察表明，制造出了从 7.97%到 19.99%的宽梯度体积分数的无缺陷菱形 FGPS，展示了对原始设计的良好几何复制。尺寸特征表明，SLM 有能力制造出 483-905µm 支柱尺寸的钛菱形 FGPS。通过调整梯度体积分数，可以将钛菱形 FGPS 的弹性模量和屈服强度分别调整到 0.28-0.59GPa 和 3.79-17.75MPa 的范围内，与松质骨相当。揭示了 FGPS 梯度孔隙率与压缩性能之间的数学关系。此外，还建立了基于 Gibson 和 Ashby 模型的两个方程，以预测 SLM 加工的菱形 FGPS 的模量和屈服强度。与均质菱形多孔支架相比，FGPS 提供了广泛的变化孔径和孔隙率，这有可能被定制以优化用于骨组织生长的孔隙空间。这些发现为设计和制造用于骨植入物应用的优质梯度支架提供了新方法的基础。
