Bending-Tension Fatigue The Influence of Fluctuating Load on the Safety of Ropes in Bending

This paper describes the development of an experimental rig to simulate the bending-tension action of a rope cycling over a sheave with tension fluctuations in phase with small bending length motions. Results are presented showing that increasing bending motions and increasing tensile load range can both lead to significant reductions in fatigue life. It is shown that at low bending lengths and low load amplitudes, the endurance in tension-tension and bending-over-sheaves fatigue modes, respectively, limit life. However despite the severe life reductions imposed by bending fatigue, the damage tends to be restricted so that moving the position of the rope can redistribute the fatigue damage thereby restoring longevity.