Implant Research Core, Drexel University School of Biomedical Engineering, Science, and Health Systems, Philadelphia, PA, USA.
Implant Research Core, Drexel University School of Biomedical Engineering, Science, and Health Systems, Philadelphia, PA, USA.
J Mech Behav Biomed Mater. 2022 Sep;133:105345. doi: 10.1016/j.jmbbm.2022.105345. Epub 2022 Jun 29.
Additively manufactured structures designed from triply periodic minimal surfaces (TPMSs) have been receiving attention for their potential uses in the medical, aerospace, and automobile industries. Understanding how these complex geometries can be designed to achieve particular architectural and mechanical properties is essential for tuning their function to certain applications. In this study, we created design tools for visualizing the interplay between TPMS design parameters and resulting architecture and aimed to validate a model of the relationship between structure architecture and Young's modulus. A custom MATLAB script was written to analyze structural properties for families of Schoen gyroid and Schwarz diamond structures, and a numerical homogenization scheme was performed to predict the effective Young's moduli of the structures based on their architecture. Our modeling methods were validated experimentally with polyetheretherketone (PEEK) structures created using material extrusion additive manufacturing. The architectural characteristics of the structures were determined using micro-computed tomography, and compression testing was performed to determine yield strength and Young's modulus. Two different initial build orientations were tested to determine the behavior both perpendicular and parallel to the layer deposition direction (referred to as z-direction and xy-direction, respectively). The z-direction Young's modulus ranged from 289.7 to 557.5 MPa and yield strength ranged from 10.12 to 20.3 MPa. For the xy-direction, Young's modulus ranged from 133.8 to 416.4 MPa and yield strength ranged from 3.8 to 12.2 MPa. For each initial build orientation, the mechanical properties were found to decrease with increasing porosity, and failure occurred due to both strut bending and interlayer debonding. The mechanical properties predicted by the modeling agreed with the values found for z-direction samples (difference 2-11%) but less so for xy-direction samples (difference 27-62%) due to weak interlayer bonding and print path irregularities. Ultimately, the findings presented here provide better understanding of the range of properties achievable for additive manufacturing of PEEK and encouraging results for a TPMS architecture-property model.
基于三次周期性极小曲面（TPMS）设计的增材制造结构因其在医疗、航空航天和汽车行业的潜在应用而受到关注。了解如何设计这些复杂的几何形状以获得特定的建筑和机械性能对于将其功能调整到特定的应用至关重要。在这项研究中，我们创建了用于可视化 TPMS 设计参数与所得结构之间相互作用的设计工具，并旨在验证结构架构与杨氏模量之间关系的模型。编写了一个定制的 MATLAB 脚本，用于分析 Schoen 回转体和 Schwarz 菱形结构族的结构特性，并进行了数值均匀化方案，以根据其结构预测结构的有效杨氏模量。我们的建模方法通过使用材料挤出增材制造创建的聚醚醚酮（PEEK）结构进行了实验验证。使用微计算机断层扫描确定了结构的建筑特征，并进行了压缩测试以确定屈服强度和杨氏模量。测试了两种不同的初始构建方向，以确定垂直和平行于层沉积方向（分别称为 z 方向和 xy 方向）的行为。z 方向的杨氏模量范围为 289.7 至 557.5 MPa，屈服强度范围为 10.12 至 20.3 MPa。对于 xy 方向，杨氏模量范围为 133.8 至 416.4 MPa，屈服强度范围为 3.8 至 12.2 MPa。对于每个初始构建方向，发现机械性能随孔隙率的增加而降低，失效是由于支杆弯曲和层间脱粘引起的。建模预测的机械性能与 z 方向样品的测量值相符（差异 2-11％），但与 xy 方向样品的测量值相差较大（差异 27-62％），原因是层间结合较弱且打印路径不规则。最终，这里提出的研究结果提供了对 PEEK 增材制造可实现的性能范围的更好理解，并为 TPMS 架构-性能模型提供了令人鼓舞的结果。
