Assessing the performance durability of elastomeric moorings: Assembly investigations enhanced by sub-component tests
Le Gac, P-Y
© 2018. This version is available under the CC-BY-NC-ND 4.0 license: https://creativecommons.org/licenses/by-nc-nd/4.0/
Reason for embargo
Currently under an indefinite embargo pending publication by Elsevier. 12 month embargo to be applied on publication
The growing marine renewable energy sector has led to a demand for increasingly compliant mooring systems. In response, several innovative mooring tethers have been proposed demonstrating potential customisation to the stiffness profi le and reduced peak mooring loads. Many of these novel systems utilise materials in a unique application within the challenging marine environment and their long term durability remains to be proven. This paper presents a multifaceted investigation into the durability of a novel polyester mooring tether with an elastomeric core. Laboratory based functionality tests are repeated on tether assemblies following a 6 month sea deployment. Results show a 45% average increase in dynamic axial stiffness. This is supported by high tension laboratory based fatigue endurance tests showing a peak increase in dynamic axial stiffness of 42%. Sub-component material tests on the core elastomer support the assembly tests, separately demonstrating that certain aspects of tether operation lead to increased material sample stiffness. The average increase in material radial compressive stiffness is 22% and 15% as a result of marine ageing and repeated mechanical compression respectively; these are the fi rst results of this type to be published. The performance durability characterisation of the tether establishes the mooring design envelope for long-term deployment. This characterisation is crucial to ensure reliable and effective integration of novel mooring systems into offshore engineering projects.
This work was supported by the Engineering and Physical Sciences Research Council, via a PhD funded through the SuperGen UKCMER programme. Additional funding was provided by the EC through the MARINET FP7 programme which funded access to the IFREMER Materials in a Marine Environment Laboratory for two weeks. The P1 Tether series were developed with assistance from Lankhorst Ropes and HEFCE through the HE Innovation Fund. The P3 and P4 Tether series were developed with Lankhorst Ropes as part of the OPERA Project, funded by the European Union's Horizon 2020 programme under grant agreement No 654.444.
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