OIPEEC Working Group - Offshore applications Proposed programme on tension fatigue

In a number of offshore applications, particularly mooring ropes, a major factor in the degradation of ropes is a fluctuating fatigue component in the tensile load. There are, of course, land-based applications where this is also a consideration, e.g. crane pendant ropes and stays for masts or aerial towers, indeed any application where a rope is fixed and there are no significant bending loads. The greater part of rope fatigue test data relates to Bending-over-Sheaves (BOS) loading and there is little reliable data published on tension-tension (T-T) fatigue. There is no published data on the cumulative effect of tension cycling at different load levels although recent work at Reading University (to be published) indicates that the most
simple application of a Palmgren-Miner hypothesis can be surprisingly accurate. What is being proposed here is a programme to involve a number of institutions in broadening the scope of the work going on at Reading with the aim of obtaining a more extensive set of fatigue data on T-T fatigue and testing the applicability of cumulative damage.

Author: C.R. Chaplin