Tianjin Key Laboratory for Control Theory & Applications in Complicated Industry Systems, School of Mechanical Engineering, Tianjin University of Technology, Tianjin 300384, PR China.
Mater Sci Eng C Mater Biol Appl. 2013 May 1;33(4):2317-22. doi: 10.1016/j.msec.2013.01.054. Epub 2013 Feb 1.
It is significant to investigate the depth-dependent mechanical behaviors of articular cartilage under rolling load since considerable rolling occurs for cartilage joint in activities of daily living. In this study, the rolling experiments of articular cartilage were conducted by applying an optimized digital image correlation (DIC) technique for the first time and the depth-dependent normal strain and shear strain of cartilage were analyzed. It is found that the normal strain and shear strain values of different layers increase firstly and then decrease with rolling time, and they increase with increasing compressive strains. The normal strain and shear strain values decrease along cartilage depth with constant compressive strain. The normal strain values of different normalized depth decrease with increasing rolling rates. The shear strain values of superficial layer and middle layer decrease; however there are no major changes for the shear strain values of deep layer with increasing rolling rates. The normal strain values with different rolling time increase with increasing rolling numbers and the 30.6% increase in initial normal strain is observed from 1st to 99th cycle. The fitting relationship of the normal strain and normalized depth was obtained considering the effects of compressive strain and rolling rate and the fitting curves agree with the experimental results for cartilage very well.
研究关节软骨在滚动载荷下的深度相关力学行为具有重要意义，因为在日常生活活动中，软骨关节会发生大量滚动。本研究首次应用优化的数字图像相关（DIC）技术对关节软骨进行了滚动实验，并分析了软骨的深度相关法向应变和切向应变。结果发现，不同层的法向应变和切向应变值随滚动时间先增加后减小，且随压缩应变的增加而增加。在恒定压缩应变下，法向应变和切向应变值沿软骨深度减小。不同归一化深度的法向应变值随滚动速率的增加而减小。表层和中层的切向应变值减小，而深层的切向应变值随滚动速率的增加没有明显变化。不同滚动时间的法向应变值随滚动次数的增加而增加，从第 1 到第 99 个循环，初始法向应变增加了 30.6%。考虑压缩应变和滚动速率的影响，获得了法向应变与归一化深度的拟合关系，拟合曲线与软骨的实验结果非常吻合。
