Experimental study on effect of additional torsional load on bending fatigue behavior and failure mechanism of steel wire rope

Abstract

Regularly replacing steel wire rope (SWR) is a mandatory measure to ensure the safe operation of the hoisting system. However, in the manual rope replacement process, the torsion accumulated in the used rope will be transmitted to the new one, thereby aggravating the damage of the new rope and shortening its fatigue life. For the sake of exploring the effect of additional torsional load on the fatigue characteristics and damage behavior of SWR, a custom fatigue test apparatus was utilized to perform relevant tests. First, the impact of torsional angle on the torque and elongation of SWR was explored; subsequently, the number and distribution of broken wires were counted, based on which the fatigue life of SWR was predicted; finally, the scanning electron microscope and confocal three-dimensional contour measuring instrument were employed to observe the wear and fracture surface morphology of the steel wire. It is found that both twisting and untwisting boost the elongation of SWR, reduce the endurance of SWR almost linearly. Of the two, twisting has a greater impact on the endurance of SWR. The surfaces of wear scars take on a regular elliptical shape in the case of twisting, and the deflection angle, together with the maximum wear depth grows with the increase of the torsional angle. In contrast, the wear scars are irregular in the case of untwisting, and the deflection angle and the maximum wear depth fall as the torsional angle increases.