Fatigue Curves for Polyester Moorings - A State-of-the-Art Review

Banfield, S.J.; Versavel, T.; Snell, R.O.; Ahilan, R.V.

doi:10.4043/12175-ms

Cited by 13 publications

(12 citation statements)

References 6 publications

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“…Synthetic ropes do not suer from corrosion problems and possess greater tension fatigue (e.g. Figure 2), out-ofplane loading and torsion performance than steel components [22,6,10,23]. Since 2001 several steel component failures have resulted in major permanent mooring incidents [24].…”

Section: Synthetic Ropes As Mooring System Componentsmentioning

confidence: 99%

Synthetic mooring ropes for marine renewable energy applications

et al. 2015

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Synthetic mooring ropes have a proven track record of use in harsh operating conditions over the past two decades. As one of the main users of ropes for permanent mooring systems, the oil and gas industry has opted for these components because they possess performance characteristics and economies of scale which are in many respects superior to steel components. Given this accrued experience, it is unsurprising that several marine renewable energy (MRE) device developers have utilised synthetic ropes, motivated by the need to specify economical, reliable and durable mooring systems. Whilst these components are potentially an enabling technology for the MRE sector, this is a new eld of application which can feature highly dynamic mooring tensions and consequently existing certication practices may not be directly applicable. Based on the expertise of the authors, this paper provides a state-of-the-art overview of synthetic ropes in the context of MRE mooring systems, including key information about aspects of specication (performance attributes, classication and testing) as well as application (installation, degradation, maintenance, inspection and decommissioning). It is the intention of this review to provide valuable insight for device developers who are considering using ropes in the specication of t for purpose mooring systems.

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Section: Synthetic Ropes As Mooring System Componentsmentioning

confidence: 99%

Synthetic mooring ropes for marine renewable energy applications

et al. 2015

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“…Whilst ultimate strength and axial sti ness have been quanti ed for the loading regimes and rope constructions relevant for large, slow-moving equipment (e.g. [2,5,6]), material and structural damping are usually not reported. As part of a dedicated component testing program involving the collaboration of L'Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) and the University of Exeter, as part of a MERiFIC (Marine Energy in Far Peripheral and Island Communities) consortium, the axial sti ness and the damping of several parallel-stranded nylon 6 rope samples are quanti ed in the context of the operational mooring loads that could be experienced by MRE devices.…”

Section: Introductionmentioning

confidence: 99%

Synthetic rope responses in the context of load history: Operational performance

et al. 2014

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The utilisation of synthetic mooring ropes for marine renewable energy (MRE) devices is a recent occurrence. Despite current use in the o shore industry, MRE mooring components are typically subjected to highly dynamic loads, necessitating the detailed characterisation of operational and long-term component performance for lifecycle analysis and operations management. To address the uncertainties associated with synthetic mooring components in this application, tension experiments have been conducted on nylon 6 parallel-stranded rope samples at IFREMER, France and the University of Exeter, UK under the consortium MERiFIC (Marine Energy in Far Peripheral and Island Communities). Measurements are reported from harmonic loading tests with di erent initial bedding-in levels used to investigate the in uence of load history on the immediate dynamic properties of the rope. Two irregular load regimes were also applied based on mooring tensions recorded by the South West Mooring Test Facility (SWMTF). Datasets are provided to facilitate the development of rope modelling tools. For the load regimes studied it was found that the operational performance of the rope is strongly in uenced by the instantaneous load-strain characteristic. This study provides unique insight into the sti ness and damping properties of synthetic rope in the context of loading regimes relevant to MRE devices.

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“…4 from [20]: The significant load range applied to the rope during the transit period was found to be 5%. Eq.…”

Section: Modelling Of the Load Experienced By The Polyester Line Durimentioning

confidence: 99%

Abrasion process between a fibre mooring line and a corroded steel element during the transit and commissioning of a marine renewable energy device

Herduin

Banfield²,

Weller

et al. 2016

Engineering Failure Analysis

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SummaryThis paper brings together two experiences from TTI (Tension Technology International) and the UoE (University of Exeter) and aims to quantify the damage that could be experienced by fibre mooring lines during the transit and commissioning phase of Marine Renewable Energy (MRE) devices.1. While deploying a new prototype of anchoring system for a MRE device, UoE experienced the failure of a new polyester mooring line during transit to site (90 minute duration). A thorough visual inspection supported by Scanning Electron Macroscopy (SEM) analysis and tensile test have established the physical conditions of the fibre rope before its failure.2. Wear testing led by TTI has investigated and established a relation between the degree of abrasion sustained and the residual strength of Dyneema ® fibre ropes. The ropes were submitted to friction forces via cycling over a roller and a fairlead with different abrasive surfaces (from 7.6 to 254.3μm). Negligible wear occurred with the low roughness surfaces and very high wear at the higher roughness surfaces.The load experienced by the polyester line during the deployment of the anchoring system was simulated with the software OrcaFlex TM . Dynamic modelling using representative conditions indicates that the polyester mooring line was loaded between 3 and 20% of its Minimum Breaking Load (MBL) which is well below the design load of the rope. IntroductionTo date there are only a few MRE designs which have achieved a pre-commercial development status. Experience in deploying such devices and specific guidance are missing. The approach of designers is thus conservative and based on the offshore oil and gas industry and anecdotal evidence [4].The use of synthetic fibre ropes for mooring systems has seen a sudden rise in marine applications over the last two decades [5] albeit mainly for deep water mooring [6]. Experience and feedback from the use of polyester ropes for MRE device moorings is still limited in terms of publications produced. This paper focuses on the commissioning phases of MRE devices, with a specific focus on the deployment of a novel anchoring system. Handling, lifting and rigging of mooring lines could result in damage during transport or installation as discussed in [7] and [8]. The strength of a rope will inevitably degrade from mishandling. Several research programs have been carried out to investigate the abrasion and twisting damage by rope manufacturers for towing systems. For example incorrect handling during transport could cause significant damage to the rope due to abrasion and the application of sudden high loads is one of the most severe conditions that a rope can experience [9].Certification standards and specific test methods have been developed to test the abrasion resistance of yarns [10] - [11]. The abrasion mechanism was described in [12] as a sequence of fibre peeling induced by surface shear forces. However the abrasion resistance of a fibre rope is not determined by standards and knowledge is only based on empirical test data.The exte...

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Fatigue Curves for Polyester Moorings - A State-of-the-Art Review

Cited by 13 publications

References 6 publications

Synthetic mooring ropes for marine renewable energy applications

Synthetic mooring ropes for marine renewable energy applications

Synthetic rope responses in the context of load history: Operational performance

Abrasion process between a fibre mooring line and a corroded steel element during the transit and commissioning of a marine renewable energy device

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