Inspection frequency of hoisting ropes based on load dependent endurance prediction
The operational manner of Koepe hoisting installations leads to dynamic loading of the ropes. ln the simple case of hoisting goods, the process of degradation of the rope is by fatigue owing to these dynamic loads. During each hoisting cycle the dynamic load reaches once its highest and lowest value. The tensions in the running rope depend on calculable static and dynamic loads and on other incalculable loads. Researches and test results in the DMT-Institüt für Förderung und Transport have shown that the highest stressed cross sections in the ropes are the acceleration areas. The dynamic load of the ropes leads to fatigue failures of both the inner and outer wires. For such ropes fatigue curves were developed. The calculation of the stresses in the rope and fatigue curves according to research and test results make the estimation of the rope life time possible. Non-destructive testing supervises the damage development. The inspection frequency is so that the point of discarding the rope is clearly determined and deviations of the normal damage development are recognised early enough to prevent unsafe operation.
Author(s): W. Spas, D. Fuchs & F. Langebrake