Assessment of damage behavior of twisted ropeway ropes in operation

Abstract

Wire ropes naturally build up torque and twist under tension or while running over sheaves. Within operation of rope drives, the twist is massaged through different rope sections and remains in specific areas, changing the ropes basic geometry. This leads to vibration, wear and a reduced rope lifetime. Former research projects could identify a relation between the dimension of twist and the rope bending cycles until failure in laboratory tests, but it was neither possible to predict the expectable amount of twist in an existing installation nor to evaluate how many rotations of a rope in operation will lead to a specific amount of twist. A funded two-years research project dealt with twist initiators, their quantitative effects and the fatiguelife of twisted ropeway-ropes. The project followed three basic topics: • Bending tests on twisted langslay ropes generating additional lifetime factors of Feyrer’s formula • Theoretic investigation on quantity of influences of mechanic twist initiators, using FMEA of relevant parameters. Comparison of rotation theory and measurements on existing ropeways with an innovative rotation sensorsystem. • Rope lay length analysis by filtered magnetoin-ductive rope test signals of almost discarded haulingropes identifying the storage of twist in jigback tramways. The results were combined to a final model allowing to predict rotation and twist storage by design parameters as well as to quantify effects on ropes lifetime.