Lifetime of running ropes stressed by fluctuating tension and bending cycles

Lifetime of ropes stressed by bending cycles or by tension-tension cycles has been investigated very well. There are formulas for the calculation of the expected number of load cycles. In the case of combining both kinds of stresses a calculation model exists too. This model defines an equivalent rope load, so that the combined load cycles can be reduced to a single bending cycle. But this model is valid for a certain load range only. Recently the author has presented a theoretical model of the total fatigue behaviour of running ropes which may be loaded by various dynamic stresses. In the following this model will be adapted to the case of fluctuating tension and bending cycles. This adapted model is valid for the whole load range. By comparison the adapted model with the existing calculation model, the new lifetime equation could be given in numbers.

Author(s): Briem, U.