Experimental and Numerical Study on Crack Propagation of Cracked Plates under Low Cycle Fatigue Loads

The traditional study on fatigue strength for ship structures usually focuses on high cycle fatigue and ignores low cycle fatigue. However, given the recent trend towards large-scale ship development, the stress and deformation experienced by ship structures are becoming increasingly significant, leading to greater attention being paid to low cycle fatigue damage. Therefore, experimental and numerical studies on crack propagation behavior of cracked plates under low cycle fatigue loads were carried out in this paper, in order to explain the fatigue crack propagation mechanism. The effect of the stress ratio and maximum applied load on the crack propagation behavior was investigated by conducting experimental research on the cracked plate of AH32 steel. The experimental results show that an increasing maximum applied load and decreasing stress ratio will shorten the fatigue life of the cracked plate. Meanwhile, based on the finite element method, the distribution of the stress–strain field at the crack tip and the effect of crack closure were evaluated. The influencing factors such as the stress ratio and crack length were considered in numerical studies, which provided a new way to study the low cycle fatigue crack propagation behavior.