摘要
通过三维数字图像相关(3D-DIC)方法研究预腐蚀2024-T4铝合金在三种不同最大应力水平和应力比下的疲劳开裂行为。通过应变场演化直观地显示裂纹萌生和扩展的时空特征,并通过扫描电镜观测关键损伤区域的断裂微观形貌。结果表明:试样边缘的局部腐蚀促进了疲劳裂纹萌生,影响了裂纹的形核位置,并引起材料氢脆现象;疲劳裂纹扩展方向与加载方向呈60°~68°角,表明疲劳裂纹扩展可以用KⅠ/KⅡ混合模式来描述;预腐蚀铝合金疲劳失效存在单裂纹断裂、多裂纹联合、多裂纹竞争和多裂纹平行扩展4种典型的失效模式。
The fatigue cracking behavior in pre-corroded AA2024-T4 associated with three different levels of maximum stresses and stress ratios via three-dimensional digital image correlation(3 D-DIC) was investigated. The spatial-temporal characteristic of crack initiation and propagation was visually displayed through strain field evolution, while the fracture morphology of determined key damage regions was further examined. Experimental results show that localized corrosion penetrated in the edges of specimens promotes fatigue crack initiation and affects crack nucleation location, accompanied with hydrogen embrittlement. Identified crack orientations(range 60°-68° from the loading direction) reveal that the early growth of fatigue crack can be described by KⅠ/KⅡ-mixed mode. Four typical failure modes(single crack fracture, multi-crack coalescence, multi-crack competition and multi-crack parallel growth) are observed and discussed.
作者
宋海鹏
刘长春
SONG Haipeng;LIU Changchun(Sino-European Institute of Aviation Engineering,Civil Aviation University of China,Tianjin 300300,China)
出处
《航空材料学报》
EI
CAS
CSCD
北大核心
2020年第2期43-52,共10页
Journal of Aeronautical Materials
基金
国家自然科学基金面上项目(11972364)
国家自然科学基金青年项目(11502285)
中央高校基本科研业务费项目中国民航大学专项项目(3122014H006)。
关键词
2024-T4铝合金
预腐蚀
疲劳
数字图像相关
断口分析
2424-T4 aluminum alloy
pre-corrosion
crack propagation
digital image correlation
fractographic analysis
