摘要
采用数字图像相关方法(DIC)研究了TC4ELI合金在相同载荷幅、高低载荷比(0.7,0.1)下疲劳裂纹扩展时裂尖塑性变形的演变。结果表明:0.7高载荷比下合金的棘轮应变和裂尖单调塑性变形程度更大,应变累积更快;0.1低载荷比下的等效应变幅更大,循环塑性变形更明显。高载荷比下的棘轮应变与等效应变幅梯度均比低载荷比下大,裂尖应变更集中。裂尖塑性区尺寸与应力强度因子呈幂函数关系。高载荷比下单调塑性区尺寸与最大应力强度因子间的指数较大,单调塑性变形对裂纹扩展起主导作用,该主导作用随裂纹长度或裂纹扩展速率的增加而增强;低载荷比下循环塑性区尺寸与应力强度因子幅间的指数较大,循环塑性变形对裂纹扩展起主导作用,该主导作用随裂纹长度或裂纹扩展速率的增加而减弱。
The evolution of plastic deformation at the crack tip during fatigue crack propagation of TC4ELI alloy under the same load amplitude and high and low load ratios(0.7,0.1)was investigated by digital image correlation(DIC)method.The results show that the ratchet strain of the alloy and the degree of monotonic plastic deformation at the crack tip under 0.7 high load ratio were larger,and the strain accumulation was faster.The equivalent strain amplitude under 0.1 low load ratio was larger and the cyclic plastic deformation was more obvious.The ratchet strain and the gradient of equivalent strain amplitude under the high load ratio were both larger than those under the low load ratio,and the strain at the crack tip was more concentrated.The size of the plastic zone at the crack tip had a power function relationship with the stress intensity factor.Under the high load ratio,the index between the size of the monotonic plastic zone and the maximum stress intensity factor was relatively large,indicating that monotonic plastic deformation played a dominant role in crack propagation the dominant role was strengthened with the increase of crack length or crack propagation rate.Under the low load ratio,the index between the size of the cyclic plastic zone and the amplitude of the stress intensity factor was relatively large,indicating that cyclic plastic deformation played a dominant role in crack propagation;the dominant role was weakened with the increase of crack length or crack propagation rate.
作者
赵询
李建
孙涛
全世超
朱建国
ZHAO Xun;LI Jian;SUN Tao;QUAN Shichao;ZHU Jianguo(Institute of Structural Health Monitoring,Faculty of Civil Engineering and Mechanics,Jiangsu University,Zhenjiang 212013,China)
出处
《机械工程材料》
北大核心
2025年第7期16-22,共7页
Materials For Mechanical Engineering
基金
中国博士后基金面上项目(2020M681496)
国家自然科学基金资助项目(52105149)
江苏省研究生科研与实践创新计划项目(KYCX24-3924)。
关键词
数字图像相关
载荷比
疲劳裂纹扩展
裂尖应变场
塑性区尺寸
digital image correlation
load ratio
fatigue crack propagation
crack tip strain field
plastic zone size
