Al-Barqawi Mohammad O, Church Benjamin, Thevamaran Mythili, Thoma Dan J, Rahman Adeeb
Department of Civil and Environmental Engineering, University of Wisconsin, Milwaukee, WI 53211, USA.
Department of Material Science and Engineering, University of Wisconsin, Milwaukee, WI 53211, USA.
Materials (Basel). 2022 May 11;15(10):3447. doi: 10.3390/ma15103447.
The availability of additive manufacturing enables the fabrication of cellular bone tissue engineering scaffolds with a wide range of structural and architectural possibilities. The purpose of bone tissue engineering scaffolds is to repair critical size bone defects due to extreme traumas, tumors, or infections. This research study presented the experimental validation and evaluation of the bending properties of optimized bone scaffolds with an elastic modulus that is equivalent to the young's modulus of the cortical bone. The specimens were manufactured using laser powder bed fusion technology. The morphological properties of the manufactured specimens were evaluated using both dry weighing and Archimedes techniques, and minor variations in the relative densities were observed in comparison with the computer-aided design files. The bending modulus of the cubic and diagonal scaffolds were experimentally investigated using a three-point bending test, and the results were found to agree with the numerical findings. A higher bending modulus was observed in the diagonal scaffold design. The diagonal scaffold was substantially tougher, with considerably higher energy absorption before fracture. The shear modulus of the diagonal scaffold was observed to be significantly higher than the cubic scaffold. Due to bending, the pores at the top side of the diagonal scaffold were heavily compressed compared to the cubic scaffold due to the extensive plastic deformation occurring in diagonal scaffolds and the rapid fracture of struts in the tension side of the cubic scaffold. The failure in struts in tension showed signs of ductility as necking was observed in fractured struts. Moreover, the fractured surface was observed to be rough and dull as opposed to being smooth and bright like in brittle fractures. Dimple fracture was observed using scanning electron microscopy as a result of microvoids emerging in places of high localized plastic deformation. Finally, a comparison of the mechanical properties of the studied BTE scaffolds with the cortical bone properties under longitudinal and transverse loading was investigated. In conclusion, we showed the capabilities of finite element analysis and additive manufacturing in designing and manufacturing promising scaffold designs that can replace bone segments in the human body.
增材制造技术的出现使得制造具有广泛结构和构造可能性的细胞骨组织工程支架成为可能。骨组织工程支架的目的是修复因极端创伤、肿瘤或感染导致的临界尺寸骨缺损。本研究对弹性模量与皮质骨杨氏模量相当的优化骨支架的弯曲性能进行了实验验证和评估。标本采用激光粉末床熔融技术制造。使用干重法和阿基米德技术对制造标本的形态特性进行了评估，与计算机辅助设计文件相比，观察到相对密度存在微小差异。使用三点弯曲试验对立方和对角支架的弯曲模量进行了实验研究，结果与数值计算结果相符。在对角支架设计中观察到更高的弯曲模量。对角支架明显更坚韧，在断裂前具有更高的能量吸收。观察到对角支架的剪切模量明显高于立方支架。由于弯曲，对角支架顶部的孔隙与立方支架相比被严重压缩，这是由于对角支架中发生了广泛的塑性变形以及立方支架拉伸侧支柱的快速断裂。支柱在拉伸时的失效表现出延性迹象，因为在断裂支柱中观察到了颈缩。此外，观察到断裂表面粗糙且无光泽，与脆性断裂时的光滑明亮表面相反。使用扫描电子显微镜观察到由于在高局部塑性变形部位出现微孔而导致的韧窝断裂。最后，研究了所研究的骨组织工程支架在纵向和横向加载下的力学性能与皮质骨性能的比较。总之，我们展示了有限元分析和增材制造在设计和制造有前景的支架设计方面的能力，这些支架设计可以替代人体中的骨段。
