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| Registros recuperados: 131 | |
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| Weller, S.d.; Davies, Peter; Vickers, A. W.; Johanning, L.. |
| The utilisation of synthetic mooring ropes for marine renewable energy (MRE) devices is a recent occurrence. Despite current use in the offshore 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 different initial... |
| Tipo: Text |
Palavras-chave: Synthetic mooring line; Nylon 6; Parallel-strand rope; Load history; Operational performance. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00186/29677/35798.pdf |
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| Martin, Nicolas; Davies, Peter; Baley, Christophe. |
| This paper presents results from an experimental study of three types of non-woven preforms (needlepunched, spunlaced and mat manufactured using a paper-making process) intended as composite reinforcement. These are potentially very attractive for transport applications. First, the influence of processing on elementary fiber tensile properties is shown to be limited. Then the preforms are evaluated in polypropylene matrix composites and mechanical properties are determined. The structure of non-woven reinforcements is strongly dependent on the manufacturing route. By varying the fiber content it is shown that the most efficient reinforcement for flax fibers is the mat produced by paper processing. The new spunlaced reinforced composites are shown to have... |
| Tipo: Text |
Palavras-chave: Flax fibers; Non-wovens; Composite materials; Polypropylene. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00307/41798/41241.pdf |
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| Davies, Peter; Morvan, C; Sire, O; Baley, C. |
| This paper presents results from a study of fibres extracted from Zostera marina eel-grass collected from the Baltic coast. This species of sea-grass is shown to contain small diameter (around 5 mu m) fibres composed of similar to 57% cellulose, similar to 38% of non-cellulosic polysaccharides (mainly xylan) and similar to 5% of residual matter so-called Klason lignin. This composition is quite different to that of commonly used terrestrial fibres. Single fibre stiffness values up to 28 GPa were measured. This stiffness combined with a low density could provide an attractive reinforcement for composite materials, and may be particularly suitable for use in bio-degradable structures. |
| Tipo: Text |
Palavras-chave: Xylan; Tension; Mechanical behaviour; IR spectroscopy; Sea grass; Fibre. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2607.pdf |
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| Baral, N; Guezenoc, H; Davies, Peter; Baley, C. |
| This paper presents test results from mode I interlaminar fracture and transverse tensile tests on unidirectional carbon/epoxy composites used in racing yacht construction. Fibre modulus has been varied from 380 to 640 GPa. PAN fibre reinforced composite properties, delamination resistance (G(Ie) and G(Ip)) and transverse strain to failure, decrease as fibre modulus increases. Composites based on the highest modulus pitch fibres show higher transverse failure strains than the highest modulus PAN fibre composites. A distinct failure mechanism, crack propagation within the fibres, was observed for the pitch based reinforcement. The transverse tensile tests allowed transverse fibre modulus to be estimated as 11.5 GPa for the PAN and 9 GPa for the pitch... |
| Tipo: Text |
Palavras-chave: Carbon fibre; Fracture; Deformation; Delamination; Composite materials. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-3723.pdf |
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| Chevillotte, Yoan; Marco, Yann; Davies, Peter; Bles, Guilhem; Arhant, Mael. |
| 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 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 [1]. The fatigue results presented here for ropes from a different supplier, confirm this result. In order to develop an accelerated evaluation of the fatigue performance, heat build-up tests have been performed, and promising first... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00441/55263/56757.pdf |
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| Davies, Peter; O'Hear, Nick. |
| Traditionally synthetic fiber ropes based on nylon and polyester fibers have been widely used in the marine industry. In recent years, as the offshore petroleum industry has moved to depths beyond 1000 meters, these have attracted more attention for both mooring and deep sea handling, and high performance ropes (high modulus polyethylenes (HMPE), aramids) are also being studied. Ocean energy converters will also require mooring systems with long term reliability. Following pioneering work by Petrobras large polyester fiber ropes are now being used in station keeping of floating platforms off Brazil and in the Gulf of Mexico [1]. This application followed extensive development projects and sea trials, and has resulted in a large database of tensile... |
| Tipo: Text |
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| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-7327.pdf |
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| Lan, Marine; Cartie, Denis; Davies, Peter; Baley, Christophe. |
| Automated fibre placement (AFP) enables the trajectory of unidirectional composite tape to be optimized, but laying down complex shapes with this technology can result in the introduction of defects. The aim of this experimental study is to investigate the influence of gaps and overlaps on the microstructure and tensile properties of carbon-epoxy laminates. First, a comparison between a hand-layup and AFP layup, draped and cured under the same conditions, shows equivalent microstructures and tensile properties. This provides the reference values for the study. Then, gap and overlap embedded defects (more or less severe) are introduced during manufacturing, on two cross-ply layups [(0°/(90°)5/0°] and [(90°/0°)2/90°]. Autoclave cure without a caul plate... |
| Tipo: Text |
Palavras-chave: Carbon fibre; Defects; Mechanical properties; Automated fibre placement (AR). |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00275/38609/37138.pdf |
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| Deroine, Morgan; Cesar, Guy; Le Duigou, Antoine; Davies, Peter; Bruzaud, Stephane. |
| In this study, natural degradation and biodegradation of poly(3-hydroxybuyrate-co-3-hydroxyvalerate) (PHBV) films were followed in different marine environments. First of all, ageing of PHBV films was investigated in natural seawater for 180 days and degradation was followed by means of weight loss measurements, scanning electron microscopy (SEM), differential scanning calorimetry and steric exclusion chromatography. In a second part, biodegradation tests were performed on PHBV powder, by following carbon dioxide (CO2) release(,) to highlight the PHBV bioassimilation of marine microorganisms. Three different marine environments were considered for biodegradation tests: a solid inoculum with foreshore sand, a solid-liquid inoculum with sand and seawater and... |
| Tipo: Text |
Palavras-chave: PHBV; Natural ageing; Degradation; Biodegradation; Seawater. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00296/40735/42020.pdf |
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| Martin, Nicolas; Davies, Peter; Baley, Christophe. |
| The industrial production of flax fibers yields two fibrous products: scutched fibers are valuable for their length, fineness and cleanness, while tows are entangled, impure and are low-priced. There is a need for technical data to compare these two kinds of fibers beyond the difference of appearance, and to assess their potential as composite material reinforcements. In this work, we have compared the properties of scutched flax and flax tows from the same batch. The morphology was first assessed by measuring the length, cleanness and fineness of fiber bundles. The tensile properties of single fibers and of unidirectionally reinforced epoxy composites were then measured. The results show that the morphology of flax tows is different from but close to the... |
| Tipo: Text |
Palavras-chave: Flax fibers; Scutching; Flax by-products; Composite materials. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00203/31403/41240.pdf |
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| Lechat, Céline; Bunsell, A; Davies, Peter; Piant, A. |
| Polyethylene naphthalate (PEN) fibres possess a higher initial stiffness than that of polyethylene terephthalate (PET) fibres and this makes them an attractive competitor for use in mooring ropes and other applications for which a low compliance would be an advantage. The two types of fibres have been characterised and compared in tension, creep and fatigue and found to behave in very similar ways. Failure of both fibres results in similar fracture morphologies although under high cyclic loading a new failure process has been observed for the PEN fibres which combines step by step crack propagation and final failure normal to the fibre axis. In the light of this observation, similar fracture behaviour has also been identified in PET fibres and which, until... |
| Tipo: Text |
Palavras-chave: Fibres; Polyethylene terephthalate; Polyethylene naphthalate; Mechanical behaviour. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1731.pdf |
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| Davies, Peter; Choqueuse, Dominique; Bourbouze, G.. |
| Although X-radiography has been widely used in studies of damage in composite materials, micro-tomography has received less attention, due to the high cost and limited availability of equipment. However, micro-tomographic analysis is a powerful tool, allowing 3D images of sections through sandwich materials to be obtained without specimen preparation. Four examples from a recent study are presented here, which show how micro-tomography can provide unique information on the quality of honeycomb sandwich structures, information on damage mechanisms and internal details of through thickness reinforcement in pinned foam cores. |
| Tipo: Text |
Palavras-chave: Inspection; Adhesive; Meniscus; Pins; Damage. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00029/14061/11311.pdf |
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| Humeau, Corentin; Davies, Peter; Le Gac, Pierre Yves; Jacquemin, Frédéric. |
| Polyamide fibres are known to be sensitive to water, and this has limited their marine applications. However, their low stiffness and high strength could be attractive for shallow water mooring line ropes, particularly for floating wind turbines. Such applications require the influence of water on mechanical behaviour to be fully understood, and this paper presents results describing how water affects static and creep response of polyamide 6 fibre yarns. First, the effect of water on fibre Tg is quantified, then tensile behaviour is examined. Finally, a model based on Schapery’s non-linear creep analysis is identified for different humidity conditions. The results show that while moisture has a small effect on short-term tensile behaviour, long term... |
| Tipo: Text |
Palavras-chave: Aging; Moisture; Fibre; Creep; Viscoelastic model. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00460/57190/59251.pdf |
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| Humeau, Corentin; Davies, Peter; Smeets, P.; Engels, T. A. P.; Govaert, L. E.; Vlasblom, M.; Jacquemin, F. |
| In order to predict the lifetime of fibre rope mooring lines it is essential to be able to predict their behaviour under tension fatigue. Creep failure is known to be a major contributor to fatigue in synthetic fibres and models to predict creep failure are well-established. We show that expansion of such models to varying loading conditions allows the prediction of the fatigue performance. However, it is difficult to design tests to quantify the fatigue performance for HMPE ropes since often premature failure occurs due to external abrasion and viscous heating due to too high testing frequencies or amplitudes. This paper presents a testing methodology which allows tensile fatigue lifetime to be evaluated by testing at higher temperature to avoid premature... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00416/52785/53684.pdf |
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| Cognard, Jean Yves; Davies, Peter; Gineste, B; Sohier, L. |
| This study is concerned with improving performance of composite structures through the use of adhesive bonding, particularly for marine and underwater applications. Some preliminary results from tests on simple composite/composite assemblies are given first. Difficulty in modelling the failure of even these simple joints highlighted the need for more reliable constituent input data. The first objective was to define an experimental methodology enabling the adhesives of interest to be characterised up to failure. A metal metal assembly was considered, in order to concentrate on the analysis of the behaviour of thin adhesive films. The aims were to characterise the adhesive, analyse its non-linear behaviour, and study the influence of parameters such as film... |
| Tipo: Text |
Palavras-chave: Finite element analysis; Adhesion. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-765.pdf |
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| Vu, Thanh Do; Durville, Damien; Davies, Peter. |
| A finite element approach to the mechanical behaviour of braided ropes at the scale of their internal components is proposed in this paper. The ropes considered are composed of a few tens of textile yarns, twisted into strands, which are then braided together. The approach aims at determining the mechanical equilibrium of such structures, viewed as assemblies of yarns undergoing large displacements and developing contact-friction interactions. To solve this equilibrium within a quasi-static framework, and using an implicit solution scheme, each yarn of the rope is represented by a finite strain beam model, and special emphasis is put on the detection and modelling of contact-friction interactions between yarns. The approach is used first to determine the... |
| Tipo: Text |
Palavras-chave: Braided rope; Finite element simulation; Contact-friction; Textile structures; Tensile properties. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00245/35647/34160.pdf |
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| Davies, Peter; Durville, Damien; Vu, Thanh Do. |
| Twist may be introduced accidentally into braided ropes during operations at sea, and it is important to know how this will affect both rope integrity and safety coefficients. This paper describes the use of simulation tools to evaluate how twisting can change the tensile properties of braided ropes. The case of a 300 kN break load 12 strand braided HMPE rope is examined. An original numerical modelling approach is presented, and results are compared with results from tensile tests performed on ropes with different levels of twist. A drop in strength of around 4% per turn per meter, and an increase in elongation, were observed as the number of turns per meter increased, corresponding to progressive removal of the load-bearing capacity of half the braided... |
| Tipo: Text |
Palavras-chave: Torsion; Rope; Braid; Numerical model. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00346/45696/45354.pdf |
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| Registros recuperados: 131 | |
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