Determination of fretting parameters of hoisting rope in coalmine and fretting-fatigue behavior of steel wires

Purpose - The objective of this paper is to determine fretting parameters of hoisting rope according to the hoisting parameters in coalmine and to explore the effect of contact load on fretting-fatigue behavior of steel wires. Design/methodology/approach - Based on the mechanical model of hoisting rope in coalmine, the dynamic tension simulation of hoisting rope was performed. Static equations of hoisting rope under tension and torsion and theories of contact mechanics were applied to obtain fretting parameters. Fretting-fatigue tests of steel wires at different contact loads were conducted using a fretting-fatigue test rig. The fretting regime, normalized tangential force and fretting-fatigue life were studied. The morphologies of fretting contact scars and fracture surfaces were observed by scanning electron microscopy and optical microscopy to examine wear and failure mechanisms. Findings - Dynamic tension changes from 0 to 30,900 N. In outer strand layer, contact loads between steel wires in certain wire layers are 60.5 and 38.3 N compared with 378 and 102.7 N between wire layers; relative displacements between wires are 62.5 and 113.2 mu m, respectively. Mixed fretting regimes develop in all cases. Increasing contact load decreases the stabilized relative slip and normalized tangential force, reduces the fretting fatigue life, induces accelerated adhesive wear and fatigue wear and results in rougher fracture surface topographies. In all cases, fretting zone induces crack initiation; crack propagation and rupture zones present brittle cleavage and longitudinal splitting, respectively. Practical implications - This paper presents the systemic study on determination of fretting parameters of hoisting rope according to the hoisting parameters in coalmine and the fretting-fatigue behavior of its internal steel wires. The results of fretting-fatigue tests show that the increase of contact load decreases the stabilized relative slip in mixed fretting regime and normalized tangential force, reduces the fretting fatigue life, induces accelerated adhesive wear and fatigue wear and results in rougher fracture surface topographies. Originality/value - The authors warrant that the paper is original submission and is not being submitted to any other journal. And the research does not involve confidentiality, copyright infringement, leaks and other issues, all the responsibilities that the authors will take.