Institute of Material Science, Professorship of Mechanics of Materials and Failure Analysis, Department of Mechanical Science and Engineering, Dresden University of Technology, Helmholtzstraße 7, 01069 Dresden, Germany; Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstraße 28, 01277 Dresden, Germany.
Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstraße 28, 01277 Dresden, Germany.
J Mech Behav Biomed Mater. 2022 Feb;126:104871. doi: 10.1016/j.jmbbm.2021.104871. Epub 2021 Oct 6.
Cellular additively manufactured metallic structures for load-bearing scaffolds in the context of bone tissue engineering (BTE) have emerged as promising candidates. Due to many advantages in terms of morphology, stiffness, strength and permeability compared to conventional truss structures, lattices based on triply periodic minimal surfaces (TPMS) have recently attracted increasing interest for this purpose. In addition, the finite element method (FEM) has been proven to be suitable for accurately predicting the deformation behavior as well as the mechanical properties of geometric structures after appropriate parameter validation based on experimental data. Numerous publications have examined many individual aspects, but conceptual design procedures that consider at least the essential requirements for cortical and trabecular bone simultaneously are still rare. Therefore, this paper presents a numerical approach to first determine the actual admissible design spaces for a choice of TPMS based lattices with respect to key parameters and then weight them with respect to further benefit parameters. The admissible design spaces are limited by pore size, strut size and volume fraction, and the subsequent weighting is based on Young's modulus, cell size and surface area. Additively manufactured beta-Ti-42Nb with a strain stiffness of 60.5GPa is assumed as material. In total, the procedure considers twelve lattice types, consisting of six different TPMS, each as network solid and as sheet solid. The method is used for concrete prediction of suitable TPMS based lattices for cortical bone and trabecular bone. For cortical bone a lattice based on the Schwarz Primitive sheet solid with 67.572μm pore size, 0.5445 volume fraction and 18.758GPa Young's modulus shows to be the best choice. For trabecular bone a lattice based on the Schoen Gyroid network solid with 401.39μm pore size, 0.3 volume fraction and 4.6835GPa Young's modulus is the identified lattice. Finally, a model for a long bone scaffold is generated from these two lattices using functional grading methods in terms of volume fraction, cell size and TPMS type. In particular, the presented procedure allows an efficient estimation for a likely suitable biometric TPMS-based scaffolds. In addition to medical applications, however, the method can also be transferred to numerous other applications in mechanical, civil and electrical engineering.
细胞增材制造的金属结构作为骨组织工程 (BTE) 中的承重支架，已经成为有前途的候选材料。与传统桁架结构相比，基于三重周期性极小曲面 (TPMS) 的晶格在形态、刚度、强度和渗透性方面具有许多优势，因此最近越来越受到关注。此外，有限元方法 (FEM) 已被证明适合于在基于实验数据进行适当参数验证后，准确预测几何结构的变形行为和力学性能。许多出版物已经研究了许多单独的方面，但同时考虑皮质骨和松质骨基本要求的概念设计程序仍然很少。因此，本文提出了一种数值方法，首先确定基于 TPMS 的晶格在关键参数方面的实际可接受设计空间，然后根据进一步的受益参数对其进行加权。可接受的设计空间受到孔径、支柱尺寸和体积分数的限制，随后的加权基于杨氏模量、细胞尺寸和表面积。假设使用应变刚度为 60.5GPa 的增材制造β-Ti-42Nb 作为材料。总共考虑了 12 种晶格类型，包括 6 种不同的 TPMS，每种晶格都有网络固体和片状固体。该方法用于预测皮质骨和松质骨用合适的基于 TPMS 的晶格。对于皮质骨，孔径为 67.572μm、体积分数为 0.5445、杨氏模量为 18.758GPa 的 Schwarz Primitive 片层固体晶格是最佳选择。对于松质骨，孔径为 401.39μm、体积分数为 0.3、杨氏模量为 4.6835GPa 的 Schoen Gyroid 网络晶格是最合适的晶格。最后，使用体积分数、细胞尺寸和 TPMS 类型的功能梯度方法，从这两种晶格生成长骨支架模型。特别是，所提出的方法允许对可能合适的生物计量学基于 TPMS 的支架进行高效估计。然而，该方法不仅可以应用于医疗应用，还可以应用于机械、土木和电气工程中的许多其他应用。
