Department of Materials Engineering, University of British Columbia, Vancouver, BC, Canada; Centre for Aging SMART, Vancouver, BC, V5Z 1M9, Canada.
School of Materials Science and Physics, China University of Mining and Technology, Xuzhou 221116, China.
J Mech Behav Biomed Mater. 2024 Dec;160:106752. doi: 10.1016/j.jmbbm.2024.106752. Epub 2024 Sep 19.
With the increasing applications of additive manufacturing in orthopaedic implants and numerous designs of porous structures available, there is a strong need and opportunity to optimize the structure designs for improved bone integration. Here we created a unique group of sheet structures based on triply periodic minimal surface (TPMS) by varying the iso-value and systematically examined how iso-value influences the mechanical performance of sheet diamond TPMS structures compared to the Octet truss structure. Four iso-values (C) 0, 0.25, 0.5, and 0.75 were designed for sheet Diamond (OSD) TPMS with varying porosity, and Ti6Al4V powder bed fusion was used to produce the porous structures. Compressive tests revealed that iso-value C significantly affected mechanical performance, and interestingly, the impact was porosity-dependent. At high relative density (>0.25), OSD0 (C = 0) displayed the highest elastic modulus and yield strength, whereas at low relative density (<0.25), OSD0.5 showed the highest among all OSD structures. Regarding failure mechanisms, OSD0, OSD0.25, and OSD0.75 showed a mixed domination of stretching and bending, while OSD0.5 was predominantly stretching-dominated. Finite Element Analysis (FEA) found that local yielding initiated at cell nodes upon loading, followed by surface bending and the formation of single or multiple shear bands near the cell nodes. This work demonstrated the feasibility of improving the mechanical performance of porous TPMS structures by simple adjustments in their governing trigonometric functions, serving as a starting point to customize porous structures for specific applications.
随着增材制造在骨科植入物中的应用越来越广泛，以及可用的多孔结构设计种类繁多，人们强烈需要并有机遇优化结构设计以提高骨整合。在这里，我们通过改变等效应值创建了一组基于三重周期性极小曲面（TPMS）的独特片状结构，并系统地研究了等效应值如何影响片状钻石 TPMS 结构与八面体桁架结构的机械性能。我们设计了四个等效应值（C）0、0.25、0.5 和 0.75，用于具有不同孔隙率的片状钻石（OSD）TPMS，并用钛 6 铝 4 钒粉末床熔合来生产多孔结构。压缩试验表明，等效应值 C 显著影响机械性能，而且有趣的是，这种影响是依赖于孔隙率的。在相对密度较高（>0.25）时，OSD0（C=0）表现出最高的弹性模量和屈服强度，而在相对密度较低时（<0.25），OSD0.5 在所有 OSD 结构中表现出最高的性能。关于失效机制，OSD0、OSD0.25 和 OSD0.75 表现出拉伸和弯曲的混合主导，而 OSD0.5 则主要是拉伸主导。有限元分析（FEA）发现，在加载时，细胞节点处首先发生局部屈服，然后是表面弯曲，以及在细胞节点附近形成单个或多个剪切带。这项工作证明了通过简单调整其控制三角函数来改善多孔 TPMS 结构机械性能的可行性，为根据特定应用定制多孔结构提供了一个起点。
