Wear Evolution in a Stranded Rope Subjected to Cyclic Bending

Wire ropes, due to their construction, combine two very interesting properties: high axial strength and flexibility in bending. However, the assemblage of wires to form flexible ropes results in the sliding of contacting wires and the creation of wear scars, which can act as stress risers and reduce the fatigue life of ropes. Therefore, in order to understand the fatigue behavior of wire ropes, the degradation that occurs between the wires and the strands has to be studied first. In this study, after identifying the main wear patterns for a polymer-covered stranded rope, the wear evolution along the number of cycles and the effect of the sheave diameter in the preferential wear sites were analyzed. The tests were carried out in a custom-made Bending over Sheave (BoS) fatigue test bench and short segments of the rope were analyzed by Scanning Electron Microscope (SEM) and confocal imaging profilometry in order to characterize the wear scars. The worn volume and the wear scar depth were selected as the most suitable parameters to characterize the wear behavior of wires. In addition, the importance of the polymeric cover and sheave diameter was proved: a reduction of the sheave diameter results in a bigger wear rate (μm³/cycle).