Mendu Kavya, Kataruka Amrita, Puthuvelil Jasmine, Akono Ange-Therese
Department of Civil and Environmental Engineering, University of Illinois at Urbana Champaign.
Department of Civil and Environmental Engineering, University of Illinois at Urbana Champaign; Department of Mechanical Science and Engineering, University of Illinois at Urbana Champaign;
J Vis Exp. 2017 Nov 30(129):56488. doi: 10.3791/56488.
Bone is a complex hierarchical material with five distinct levels of organization. Factors like aging and diseases like osteoporosis increase the fragility of bone, making it fracture-prone. Owing to the large socio-economic impact of bone fracture in our society, there is a need for novel ways to assess the mechanical performance of each hierarchical level of bone. Although stiffness and strength can be probed at all scales - nano-, micro-, meso-, and macroscopic - fracture assessment has so far been confined to macroscopic testing. This limitation restricts our understanding of bone fracture and constrains the scope of laboratory and clinical studies. In this research, we investigate the fracture resistance of bone from the microscopic to the mesoscopic length scales using micro scratch tests combined with nonlinear fracture mechanics. The tests are performed in the short longitudinal orientation on bovine cortical bone specimens. A meticulous experimental protocol is developed and a large number (102) of tests are conducted to assess the fracture toughness of cortical bone specimens while accounting for the heterogeneity associated with bone microstructure.
骨骼是一种具有五个不同组织层次的复杂分级材料。衰老等因素以及骨质疏松症等疾病会增加骨骼的脆性，使其易于骨折。由于骨折在我们社会中具有巨大的社会经济影响，因此需要新的方法来评估骨骼各个分级层次的力学性能。尽管刚度和强度可以在所有尺度——纳米、微观、细观和宏观——上进行探测，但迄今为止，骨折评估仅限于宏观测试。这种局限性限制了我们对骨折的理解，并制约了实验室和临床研究的范围。在这项研究中，我们使用微划痕试验结合非线性断裂力学，从微观到细观长度尺度研究骨骼的抗断裂性。试验在牛皮质骨标本的短纵向取向上进行。制定了详细的实验方案，并进行了大量（102次）试验，以评估皮质骨标本的断裂韧性，同时考虑与骨微观结构相关的异质性。
