Department of Mechanical and Manufacturing Engineering, Atlantic Technological University, Ash Lane, Sligo, F91 YW50, Ireland; Centre for Precision Engineering Material and Manufacturing Research (PEM Research Centre), Atlantic Technological University, Ash Lane, Sligo, F91 YW50, Ireland; Centre for Mathematical Modelling and Intelligent Systems for Health and Environment (MISHE), Atlantic Technological University, Ash Lane, F91 YW50 Sligo, Ireland.
Department of Mechanical and Manufacturing Engineering, Atlantic Technological University, Ash Lane, Sligo, F91 YW50, Ireland; Centre for Precision Engineering Material and Manufacturing Research (PEM Research Centre), Atlantic Technological University, Ash Lane, Sligo, F91 YW50, Ireland.
J Mech Behav Biomed Mater. 2024 Dec;160:106757. doi: 10.1016/j.jmbbm.2024.106757. Epub 2024 Sep 30.
Currently, cutting-edge Additive Manufacturing techniques, such as Selective Laser Melting (SLM) and Electron Beam Melting (EBM), offer manufacturers a valuable avenue, especially in biomedical devices. These techniques produce intricate porous structures that draw inspiration from nature, boast biocompatibility, and effectively counter the adverse issues tied to solid implants, including stress shielding, cortical hypertrophy, and micromotions. Within the domain of such porous structures, Triply Periodic Minimal Surface (TPMS) configurations, specifically the Gyroid, Diamond, and Primitive designs, exhibit exceptional performance due to their bioinspired forms and remarkable mechanical and fatigue properties, outshining other porous counterparts. Consequently, they emerge as strong contenders for biomedical implants. However, assessing the mechanical properties and manufacturability of TPMS structures within the appropriate ranges of pore size, unit cell size, and porosity tailored for biomedical applications remains paramount. This study aims to scrutinize the mechanical behavior of Gyroid, Diamond, and Primitive structures in solid and sheet network iterations within the morphological parameter ranges suitable for tasks like cell seeding, vascularization, and osseointegration. A comparison with the mechanical characteristics of host bones is also undertaken. The methodology revolves around Finite Element Method (FEM) analysis. The six structures are originally modeled with unit cell sizes of 1, 1.5, 2, and 2.5 mm, and porosity levels ranging from 50% to 85%. Subsequently, mechanical properties, such as elasticity modulus and yield strength, are quantified through numerical analysis. The results underscore that implementing TPMS designs enables unit cell sizes between 1 and 2.5 mm, facilitating pore sizes within the suitable range of approximately 300-1500 μm for biomedical implants. Elasticity modulus spans from 1.5 to 33.8 GPa, while yield strength ranges around 20-304.5 MPa across the 50%-85% porosity spectrum. Generally, altering the unit cell size exhibits minimal impact on mechanical properties within the range above; however, it's noteworthy that smaller porosities correspond to heightened defects in additively manufactured structures. Thus, for an acceptable pore size range of 500-1000 μm and a minimum wall thickness of 150 μm, a prudent choice would involve adopting a 2.5 mm unit cell size.
目前，先进的增材制造技术，如选择性激光熔化（SLM）和电子束熔化（EBM），为制造商提供了一个有价值的途径，特别是在生物医学设备领域。这些技术可以制造出从自然界中汲取灵感的复杂多孔结构，具有生物相容性，并有效地解决了与实心植入物相关的负面问题，如应力屏蔽、皮质肥大和微动。在这些多孔结构中，三重周期性极小曲面（TPMS）结构，特别是胞元形状为 gyroid、diamond 和 primitive 的结构，由于其仿生形式和出色的机械和疲劳性能而表现出色，优于其他多孔结构。因此，它们成为生物医学植入物的有力竞争者。然而，评估 TPMS 结构在适合生物医学应用的孔径、胞元尺寸和孔隙率范围内的机械性能和可制造性仍然至关重要。本研究旨在研究 gyroid、diamond 和 primitive 结构在实心和板状网络迭代中的力学行为，这些结构的形态参数范围适合细胞播种、血管化和骨整合等任务。还与宿主骨骼的机械特性进行了比较。该研究方法围绕有限元法（FEM）分析展开。最初，使用胞元尺寸为 1、1.5、2 和 2.5mm 的六种结构进行建模，孔隙率范围为 50%至 85%。然后，通过数值分析量化了弹性模量和屈服强度等机械性能。研究结果表明，采用 TPMS 设计可以实现 1 至 2.5mm 的胞元尺寸，为生物医学植入物提供了 300-1500μm 左右的合适孔径范围。弹性模量范围为 1.5 至 33.8GPa，屈服强度范围为 20 至 304.5MPa，适用于 50%-85%的孔隙率范围。一般来说，在上述范围内改变胞元尺寸对力学性能的影响很小；然而，值得注意的是，较小的孔隙率对应于增材制造结构中的更高缺陷。因此，对于可接受的孔径范围为 500-1000μm 和最小壁厚度为 150μm，明智的选择是采用 2.5mm 的胞元尺寸。
