Kunststoffummantelte Drahtseile: experimentelle, numerische und analytische Untersuchungen zur Lebensdauer

Abstract

Plastic-coated wire ropes are characterised by a significantly longer lifetime than conventional wire ropes. The criteria for changing damaged conventional wire ropes are defined in standards for the corresponding design structure of the rope and the rope drive. There are no standards for coated ropes. Similar to the standards for the determination of discard state, theoretical methods for the estimation of lifetime do not have any approaches for plastic-coated wire ropes. This paper presents the experimental, numerical and analytical studies on the damage behaviour of the wire rope with additional plastic coating for an established rope construction as well as their consideration in the analytical lifetime estimation. Experimental bending fatigue tests were used to determine the lifetime at different D/d-ratios and loads. The stresses on the rope wires, in particular the compressive stress when running over sheaves, were investigated using the finite-element-method (FEM). The load case of a running wire rope during the roll-over of a sheave was simulated using the experimentally used parameters. The focus here was on the change in the distribution of the compressive stress in the outer wires of the rope construction as a result of the coating. Based on the findings on the distribution of compressive stress in coated ropes from the FE-simulations and the results of the bending fatigue tests, the reduction of the compressive stress was integrated into an estimation method. Bending fatigue tests were performed with three rope variants. The lifetime of the conventional wire ropes was compared with the lifetime of the plastic-coated ropes in order to experimentally determine the influence of the coating on the increase in lifetime due to achievable bending cycles. The numerical results of the compressive stress could be integrated into the analytical approach of the lifetime estimation and were validated by the test data. The paper shows that an additional plastic coating of the wire rope generates a considerable increase in lifetime. In practical use, this can significantly increase the economic efficiency of applications.