Pengfei Cui, Jianqiang Zhang, Wanlin Guo

International Journal of Fatigue   ，2025，109042

Abstract: Fatigue crack closure (FCC) and growth (FCG) behavior under variable amplitude loading (VAL) are ubiquitous in engineering structures. With the plasticity-induced cack closure concept, Budiansky and Hutchinson (1978) pioneered the analytical FCC model under plane stress state and constant amplitude loading (CAL) conditions with stress ratio R ≥ 0. Here, we developed the analytical model into three-dimensional (3D) FCC and FCG under VAL, by which the FCG life under CAL as well as VAL can be predicted only based on the FCG data from the standard CAL testing, and free from any empirical parameters. Under CAL, the present model shows that the opening-stress ratio increases with increasing stress ratio and decreases with increasing applied maximum stress and 3D constraint levels, in good agreement with finite element and experimental data from the literature. Validations against one hundred and thirty-three experiments available from the literature, including eight materials and three types of specimens with through-the-thickness and surface cracks, show that the predicted FCG life is within 0.4 to 2.5 times of the experimental results under both CAL and VAL. It is found that the coupling effects of stress ratio, 3D constraint, applied maximum stress and load history on FCC and FCG can be effectively unified by the present theoretical model.

Link: https://www.sciencedirect.com/science/article/abs/pii/S0142112325002397