摘要
采用稳态裂纹扩展和疲劳裂纹扩展的实验,研究了牛皮质骨横向和纵向裂纹扩展的断裂力学行为.沿着两个方向制备了紧凑拉伸(CT)试件.由于试件尺寸的限制,采用数值计算方法确定了裂纹尖端应力强度因子与裂纹长度的关系.在实验中,采用数字图像相关法精确测定裂纹尖端的位置.由于裂纹沿横向扩展时有较大的偏斜,将采用J积分测量其断裂韧性.实验结果表明,在裂纹扩展的一定范围内,皮质骨的断裂韧度随着裂纹不断扩展而增大,即表现出上升的阻力曲线(R-curve)性质.而皮质骨的横向裂纹扩展的断裂韧度要远远大于纵向裂纹扩展的断裂韧度,表现出各向异性的阻力曲线行为.在疲劳裂纹扩展中,纵向疲劳裂纹扩展率要大于横向疲劳裂纹扩展率,这说明皮质骨具有各向异性的疲劳裂纹扩展性质.
The transverse and longitudinal crack propagation behaviors in bovine cortical bone were studied using stable crack growth and fatigue test methods.Twenty five Compact Tension（CT） specimens of cortical bone were prepared in specific directions.In stable crack growth experiment,the ASTM standard is no longer applicable due to the geometry of the CT specimens and anisotropy of the materials.The relationship between the stress intensity factor and crack length was established by means of numerical method.In order to identify the location of crack tip during crack propagation,Digital Image Correlation（DIC） method was used.As the crack deflected largely when propagating in the transverse direction,the transverse fracture toughness was analyzed with J integral.The results show that the fracture toughness of cortical bone increases with crack extension in a certain range,i.e.cortical bone exhibits rising resistance curve（R-curve）.And the fracture toughness in the transverse direction is much higher than that in longitudinal direction,which indicates that the R-curve is anisotropic.The fatigue test shows that fatigue crack propagation behavior in cortical bone is also anisotropic.Crack grow rate in the longitudinal direction is greater than that in transverse direction.It is also found that the fatigue crack growth rate decreases with the increase of stress intensity factor range at the initial stage of crack extension.
出处
《力学学报》
EI
CSCD
北大核心
2010年第6期1164-1171,共8页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家自然科学基金资助项目(10772111)~~
关键词
皮质骨
断裂韧度
疲劳
裂纹扩展速率
各向异性
cortical bone fracture toughness fatigue crack growth rate anisotropy
