Influence of Surface Wear Defect on Low-Cycle Bending Fatigue Performance of Single-Strand Steel Wire Ropes

To investigate the fatigue life and failure mechanisms of single-strand wire ropes with surface defect (WR-SD) under bending loads, a finite element (FE) analysis model for low-cycle bending fatigue behavior is established based on the constant strain amplitude cyclic loads applied to single-strand WR-SD. Firstly, by comparing with the analytical formula, the optimal length of the FE model for different lay angles is determined, indicating that the prediction results are reasonable when the length of the FE model of single-strand wire ropes is at least 80% of the lay length. Subsequently, using the optimal FE model, the bending fatigue life of WR-SD is estimated, and the influence of the angle between the defect direction and the bending direction is investigated systematically. The simulated results show that under cyclic bending loads, the defective area of the wire rope is damaged first, while the defect-free wire ropes (WR-DF) are damaged first at the interwire contact positions. Surface defects alter the distribution rule of bending fatigue life of single-strand wire ropes, leading to a reduction in overall load-bearing capacity. Different angles between the defective direction and the bending direction could result in symmetric changes in the distribution of fatigue life. The wire rope exhibits the weakest load-bearing capacity at a 45-degree angle, while at 90 degrees, it shows the strongest load-bearing capacity, making it relatively safer for operation.