Fatigue of improved polyamide mooring ropes for floating wind turbines

Yoan Chevillotte (1) , Yann Marco (1) , Guilhem Bles (1) , Karel Devos (2) , Mathieu Keryer (3) , Maël Arhant (4) , Peter Davies (4)

1 IRDL - Institut de Recherche Dupuy de Lôme
2 Bexco
3 Naval Energies
4 IFREMER - Institut Français de Recherche pour l'Exploitation de la Mer

This paper describes a study of the fatigue characterization of polyamide mooring ropes for floating wind turbines. Under some conditions polyester ropes, which are favoured for offshore oil and gas platform station-keeping, are too stiff for wind turbine moorings, and polyamide may be a suitable alternative. While early studies on fatigue of braided nylon ropes showed very short lifetimes some recent results have indicated that it is possible to significantly enhance lifetime by modifying rope construction and improving fibre coatings. In this paper yarn-on-yarn abrasion testing is used first to evaluate a new yarn coating. Significant lifetime enhancement was noted, so fatigue testing of ropes was then performed. Results confirm that excellent fatigue lifetimes can be achieved, superior to those for steel chain. Finally, failed yarn and rope samples were examined by microscopy, in order to improve understanding of the fatigue mechanisms leading to failure.

Keywords: Rope; Nylon; Fatigue; Floating wind turbine; Mooring; Water

Domains: Engineering Sciences [physics]; Materials and structures in mechanics [physics.class-ph]

Yoan Chevillotte, Yann Marco, Guilhem Bles, Karel Devos, Mathieu Keryer, et al.. Fatigue of improved polyamide mooring ropes for floating wind turbines. Ocean Engineering, 2020, 199, pp.107011-1 - 107011-9. ⟨10.1016/j.oceaneng.2020.107011⟩. ⟨hal-02493828⟩