Tensile–bending fatigue properties of a 7-wire steel strand considering wear

This study investigated the tensile–bending fatigue performance of a 7-wire steel strand. To this end, 13 specimens were tested under different conditions, followed by a fatigue performance evaluation process for strand tension–bending accounting for wear, combining a critical plane method, an Archard correction model, the Miner’s cumulative damage theory, the UMESHMOTION subroutine, an adaptive mesh technology, a multi-scale finite element model (MSFEM), etc. The results showed that the tension–bending fatigue life gradually decreased from 794524 to 12481, with increasing deflection angle, axial tensile force, and axial stress amplitude. For most specimens, cracks originated at the upper edge of the midspan, which corresponded to the point of maximum bending stress amplitude. However, in a few cases, the wear of the middle and lower edge wires primarily contributed to failure. The MSFEM analysis results, indicating the crack-initiation locations and service life, agree with the experimental results. The crack-initiation lives accounted for approximately 90% of the fatigue life (fracture of the first wire). In the early stage of loading, when N < 500, the contact pressure between the steel wires or between the steel wires and the fixture was the highest, exhibiting the most drastic changes and rapid increases in wear. Beyond this value, the changes in contact pressure plateaued.