Study On Multiaxial Fretting Fatigue Behaviors Of Steel Wires

The hoisting rope in coal mine,subjected to cyclic tension and torsion,presents tension-torison multiaxial fretting fatigue damage,which accelerates the fatigue fracture of rope wires and thus affects the reliability of steel wire rope.Therefore,it is of great significance to investigate the tension-torison multiaxial fretting fatigue behaviors of steel wires in order to prolong the rope service life and to enhance the steel wire rope reliability.In this paper,a tension-torsion multiaxial fretting fatigue test rig of steel wires was developed.Comparative studies of torsion fretting,tension-tension fretting-fatigue and tension-torsion multiaxial fretting-fatigue behaviors of steel wires were carried out.Tension-torsion multiaxial fretting-fatigue tests of steel wires at simplified crossing angle of 90° and the actual twist crossing angle of 26.2° were carried out.Evolutions of wear profile,wear coefficient and fretting map,and wear mechanisms during tests at distinct crossing angles were presented.Meanwhile,effects of contact load and torsion angle on multiaxial fretting fatigue behaviors were explored.The results show that tension-torsion multiaxial fretting fatigue causes the most severe damage.Top views of wear scars of fatigue wires in the tests at crossing angles of 90° and 26.2° both exhibit irregularly elliptical shapes,and maximum length,width and depth of the wear scar all increase with increasing fatigue cycles.The wear coefficient in the test at crossing angle of 90°shows the increase at first and then stabilizes to a constant value as compared to the decrease at first and then an increase in the case of crossing angle of 26.2°.In cases of crossing angles of 90° and 26.2°,hysteresis loops of tangential force-fretting amplitude both changes from parallelogram to elliptical shape,and fretting is located in the partial slip region and mixed region,respectively;hysteresis loops of torque-torsion angle all present large opening during the whole test in both cases.Wear mechanisms are always adhesive wear,abrasive wear and fatigue wear in both cases.With the increase of the contact load and torsion angle,the relative slip range of contact wire decreases and increases,the coefficient of friction decreases and the acceleration of surface damage.