Full-Scale Fiber Deepwater Mooring Ropes: Advancing the Knowledge of Spliced Systems

摘要

This paper reports on the results of an investigation into thernstiffness behaviour of polyester ropes in the size range 600 torn1,000 tonne. Both quasi-static and dynamic stiffness datarnhave been presented. Effects of dynamic stiffness have beenrnquantified for a wide range of loading conditions under bothrnsinusoidal and stochastic loading. It has been demonstratedrnthat for the test conditions used and the associated analysisrntechniques employed, strain amplitude does exist as a variable.rnHowever, for stochastic loading its effect is sufficiently smallrnthat it could be neglected when considering dynamic stiffnessrnbehaviour for mooring design under low strain amplitudes uprnto 0.3%. (Strain amplitudes around 0.25% are relevant for tautrnmoorings of typical floaters in 1,500 m harsh environmentrnwater depth). At higher strain amplitudes, around 0.6% therneffect should not be ignored. It should also be noted thatrnmaterial and construction effects affect dynamic modulus.rnTherefore, for some materials and constructions at higherrnstrain amplitudes of 0.6%, it may be possible to ignore thernstrain amplitude dependence. For a broad comparison, all thernmaterials and constructions reported herein fall within arnrelatively narrow axial stiffness band for a given set of testrnconditions. This generic data will be useful for mooringrnsystem designers enabling preliminary designs to bernconducted with confidence. To ensure the correct stiffnessrnvalues are determined, detailed engineering should be basedrnon test data generated on full scale rope and at loadingrnconditions representative of the actual mooring.