密质骨各向异性性质的力学实验及细观分析

目的 研究牛股骨密质骨的微观结构特征与其力学行为间的关系。方法 对牛股骨密质骨纵向和横向试样分别进行压缩实验；对破坏后的纵向和横向试样进行断裂路径、断裂表面微结构特征观察；基于复合材料细观力学的理论，分析密质骨中骨单元方向对骨纵向和横向弹性模量及断裂极限强度的影响。结果 纵向试样的压缩弹性模量和断裂极限强度均明显大于横向试样的压缩弹性模量和断裂极限强度；纵向试样的断裂路径与加载方向近似为0°，且比较平直，而横向试样的断裂路径与加载方向近似为45°，且比较曲折；纵向试样断面中存在许多与加载方向平行的条状结构，断面较为光滑，而横向试样断面存在许多圆弧形凹坑或凸起，断面较为粗糙。结论 牛股骨密质骨具有各向异性的力学性质，其各向异性力学性质与骨单元方向密切相关。
Objective To investigate the relationship between microstructure characteristics and its mechanical behavior. Methods The compression experiments on longitudinal and transverse specimens of the cortical bone from bovine femoral bone were conducted. The fracture routes of longitudinal and transverse specimens and microstructural features of fractured surfaces were observed. The effects of osteon orientation on elastic modulus and ultimate fracture strength of the bone were analyzed based on the theory of composite micromechanics. Results The compressive elastic modulus and ultimate fracture strength of longitudinal specimens were significantly greater than those of transverse specimens. The fracture routes of longitudinal specimens were along their loading direction (0°) and relatively flat, while the fracture routes of transverse specimens were relatively zigzagging, being approximately 45° with their loading direction. There were many striped structures on fractured surfaces of longitudinal specimens and the fractured surfaces were relatively smooth, while there were many annular concave and convex structures on fractured surfaces of transverse specimens and the fractured surfaces were relatively rough. Conclusions The bovine femoral bone had anisotropic mechanical properties, and its anisotropic mechanical properties were closely related to the orientation of osteons.