Parameter estimation for synthetic rope models
Weller, SD; Banfield, SJ; Canedo, J
Date: 17 June 2018
Conference paper
Publisher
ASME
Publisher DOI
Abstract
With widespread market penetration in the offshore sector,
synthetic rope materials offer a range of axial compliance that
can be exploited for mooring design, ranging from stiff (e.g. high
modulus polyethylene) to soft (e.g. nylon). For new applications,
such as the marine renewable energy (MRE) sector synthetic
ropes are potentially ...
With widespread market penetration in the offshore sector,
synthetic rope materials offer a range of axial compliance that
can be exploited for mooring design, ranging from stiff (e.g. high
modulus polyethylene) to soft (e.g. nylon). For new applications,
such as the marine renewable energy (MRE) sector synthetic
ropes are potentially an enabling technology due to their load
reduction properties and relative low cost compared to
conventional mooring component materials.
Existing design, test and certification procedures for ropes
were developed for the station keeping of large offshore
equipment. Arrays of small, reactive MRE devices will have an
entirely different set of mooring load cases with the mooring
system potentially an integral part of the power take off system.
Larger devices are also likely to be subjected to complex loading
as MRE deployment sites are typically highly energetic in terms
of wind, wave and/or tidal energy. Consequently devices and
associated subsystems are subjected to dynamic load cases in a
wide range of complex environmental and operating conditions.
Underpinning research is therefore required to understand the
behaviour of synthetic materials subjected to highly dynamic
loading regimes in terms of operational performance and longterm
durability as these factors could have a significant impact
on coupled device performance and availability. At present
conventional mooring analyses is based on the use of simplified
rope characteristics, although several studies including a Joint
Industry Project (Syrope) have investigated these aspects.
However, at present an industry-standard method to account for
the time-varying behaviour of synthetic ropes for offshore
equipment moorings does not exist.
The SynMaRE (Synthetic ropes for Marine Renewable
Energy mooring systems) project aims to develop a time domain
analytical model that can adequately represent the time
dependent and non-trivial behaviour of synthetic ropes. Instead
of being a stand-alone tool, it is intended that the model will be
adopted for incorporation in (or with) commercial mooring
system software allowing the prediction of mooring loads and
device responses to an increased level of accuracy. This paper
will present findings from an initial assessment of parameter
estimation techniques utilising a simplified viscoelastic and
viscoplastic model and validation scenarios based on physical
tension-tension test data featuring load cases relevant to MRE
Engineering
Faculty of Environment, Science and Economy
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