Low-cycle tensile fatigue performance of a wire rope strand with an internal flaw in varied position and direction

Taking into account the effects of mean stress, elastic-plasticity and nonlinear contact, the finite element model of the tensile fatigue performance of an internal flawed wire rope strand is built by using the local stress strain method in the present study. A mesh model of the strand with a high-precision feature is established through a block-based method and refinement in the flaw region. The strand with a flaw is investigated to explore its fatigue life distribution, and the effects of the flaw’s position and direction on the strand’s fatigue and bearing performances are analyzed. The numerical results demonstrate that the low-cycle fatigue life zone occurs at the interwire contact region of the intact wire rope strand, while is located at the flaw region of the wire rope strand with an internally flawed wire. The minimum fatigue life of the wire rope strand decreases due to the occurrence of the internal flaw. Moreover, as the internal flaw’s direction angle decreases, the strand’s minimum fatigue life is reduced, and the internal flaw with the major axis perpendicular to the strand axis is the most dangerous. The internal flaw in the outer wire has a more severe influence on the fatigue property of the wire rope strand than a core wire flaw with the same dimension and direction. The wire rope strand is more prone to stress yielding due to the internal flaw, and the effect is getting more significant as the internal flaw’s direction angle decreases.