Jin Huijin, Cui Bing, Mao Ling
State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
School of Materials Science and Engineering, Anhui University of Technology, Ma'anshan 243000, China.
Materials (Basel). 2019 Oct 28;12(21):3526. doi: 10.3390/ma12213526.
Under cyclic fatigue load, multiple cracks would significantly deteriorate the service life of the components with respect to the case of a single crack owing to the crack interaction. The present study aims to explore the effect of crack interaction on the fatigue growth behaviour of samples with different crack offset. In this study, fatigue crack growth tests were performed for samples containing a single crack and non-collinear cracks of different crack offset in an aluminum-lithium alloy. It was shown that the two facing non-collinear cracks changed their growth direction when the cracks were overlapped, resulting in load mode transfers from mode I to I + II mixed mode. Then, the interaction behaviour was studied by establishing the finite element models to calculate the stress intensity factor K of samples with different crack offset. The results indicated that the K decreased, largely owing to the shielding effect as the two cracks overlapped, leading to retardation of crack growth in the position of overlap, especially for the specimens with a small crack offset. It was also shown that the interaction effect could change from positive to negative during the process of the multiple cracks' growth, thus leading to the acceleration or deceleration of crack growth rates, suggesting that the influence of interaction on cracks' growth behaviour could vary with the different stages of crack growth.
在循环疲劳载荷作用下，由于裂纹相互作用，与单裂纹情况相比，多个裂纹会显著降低部件的使用寿命。本研究旨在探讨裂纹相互作用对不同裂纹偏移量试样疲劳扩展行为的影响。在本研究中，对含单裂纹以及铝锂合金中不同裂纹偏移量的非共线裂纹的试样进行了疲劳裂纹扩展试验。结果表明，当两个相对的非共线裂纹重叠时，它们会改变扩展方向，导致载荷模式从Ⅰ型转变为Ⅰ + Ⅱ混合型。然后，通过建立有限元模型来计算不同裂纹偏移量试样的应力强度因子K，研究了相互作用行为。结果表明，当两个裂纹重叠时，由于屏蔽效应，K值降低，导致重叠位置处的裂纹扩展受阻，尤其是对于裂纹偏移量较小的试样。研究还表明，在多裂纹扩展过程中，相互作用效应可能从正向变为负向，从而导致裂纹扩展速率的加速或减速，这表明相互作用对裂纹扩展行为的影响可能随裂纹扩展的不同阶段而变化。
