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| Registros recuperados: 131 | |
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| Davies, Peter; Arhant, Mael. |
| The recent introduction of liquid acrylic thermoplastic matrix resins which can impregnate fibre reinforcements using traditional infusion moulding offers significant potential for future composite structures in marine applications, such as marine energy devices. However, to date very few results are available to evaluate the long term durability of these composites in a marine environment. This paper describes results from a series of cyclic loading tests on glass and carbon fibre reinforced acrylic composites under both tension and four point flexural loading. Tests were performed before and after aging in natural seawater. The results were compared to results for a glass/epoxy used today in marine structures, and show a lower loss of both static and... |
| Tipo: Text |
Palavras-chave: Acrylic; Fatigue; Immersion; Seawater. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00444/55596/57249.pdf |
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| Le Gac, Pierre-yves; Davies, Peter; Choqueuse, Dominique. |
| Polymers and composites are very attractive for underwater applications, but it is essential to evaluate their long term behaviour in sea water if structural integrity of offshore structures is to be guaranteed. Accelerated test procedures are frequently required, and this paper will present three examples showing how the durability of polymers, in the form of fibres, matrix resins in fibre reinforced composites for structural elements, and thermal insulation coatings of flow-lines, have been evaluated for offshore use. The influence of the ageing medium, temperature, and hydrostatic pressure will be discussed first, then an example of the application of ageing test results to predict long term behavior of the thermal insulation coating of a flowline will... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00199/30978/29356.pdf |
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| Tarfaoui, Mostapha; Gning, P.b.; Davies, Peter; Collombet, F. |
| The impact behavior of composite materials has been extensively studied but interest has been centered on flat plates. For underwater applications, thick composite cylinders are employed and several questions must be addressed concerning the influence of accidental impact. The aim of this work is to study the dynamic response of tubular structures. Such structures find many applications but the damage upon impact is not taken into account during their dimensioning. However, at the time of their handling or in service the damage introduced by accidental impact can compromise their capacity to fulfill their function. The cylinders are thick and consist of epoxy matrix and glass fiber reinforcement. After having observed the nature of the damage related to... |
| Tipo: Text |
Palavras-chave: Size effect; Scale effect; Damage; Impact; Filament winding. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2458.pdf |
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| Davies, Peter; Reaud, Yvan; Dussud, Loic; Woerther, Patrice. |
| This paper describes the mechanical behaviour of ropes used for deep sea oceanographic operations. First the requirements of deep sea handling ropes are presented. Two high performance fibres are commonly used, aramid co-polymer and high modulus polyethylene (HMPE), and these are then compared. Results from tests on single fibres and 50 ton break load braided ropes are presented, which show that the initial stiffness of a new HMPE rope increases with load level in a bedding-in process resulting from both molecular alignment and construction reorientation. The aramid rope is less sensitive to this effect and shows a high stiffness from first loading. Measurements made at sea on oceanographic ropes of both materials using an elastic recoil method are... |
| Tipo: Text |
Palavras-chave: Fibre rope; Deep sea coring; Stiffness; Aramid; HMPE. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00054/16573/14068.pdf |
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| Davies, Peter; Sohier, L.; Cognard, J. -y.; Bourmaud, A.; Choqueuse, Dominique; Rinnert, Emmanuel; Creac'Hcadec, R.. |
| While the geometry of aerospace assemblies is carefully controlled, for many industrial applications such as marine structures bond line thickness can vary significantly. In this study epoxy adhesive joints of different thicknesses between aluminium substrates have been characterized using physico-chemical analyses (differential scanning calorimetry, DSC; dynamic mechanical analysis, DMA; spectroscopy), nano-indentation and mechanical testing. Thermal analyses indicated no influence of thickness on structure. Nano-indentation revealed no evidence of an interphase at the metal/epoxy interface, nor any change in modulus for different thicknesses, though Raman spectroscopy suggested there may be slight variations in composition close to the substrates.... |
| Tipo: Text |
Palavras-chave: Arcan; Mechanical properties; Aluminium; Epoxy. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6638.pdf |
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| Le Gac, Pierre-yves; Arhant, Mael; Le Gall, Maelenn; Davies, Peter. |
| This paper considers the effect of water content on mechanical properties of polyamide 6 when used in a humid environment. First an experimental section presents the tensile behavior of polyamide with different amounts of water, with and without a through-thickness water gradient. Water profiles are introduced by immersion in sea water at 25 °C. The effect of testing temperature is also investigated in order to consider the influence of macromolecular chain mobility on the mechanical behavior. Then, in a second section, modelling of yield stress is proposed based on physical considerations. This can be used for life time prediction of PA6 in humid environment when plasticization is the main degradation mechanism. |
| Tipo: Text |
Palavras-chave: Yield stress; Water; Polyamide; Plasticization; Prediction. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00371/48208/48321.pdf |
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| Sar, B. E.; Freour, S.; Davies, Peter; Jacquemin, Frederic. |
| A thermodynamical approach, based on the definition of the chemical potential of water, is used in order to establish a model coupling the diffusion of moisture to the mechanical behaviour of a polymer. The model takes into account the evolution, occurring during the diffusion process, of both the density of the polymer and its maximum moisture absorption capacity. The approach developed is applied to symmetric loading cases, in terms of relative humidity and external pressure. The model, established in the present work, provides the water content profiles through the thickness of the polymer throughout the transient phase of the diffusion process. The numerical results obtained show the significant effect of an external pressure on the kinetics of... |
| Tipo: Text |
Palavras-chave: Hygromechanical coupling; Moisture absorption; Thermodynamical approach. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19932/17755.pdf |
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| Floreani, Christophe; Robert, Colin; Alam, Parvez; Davies, Peter; Ó. Brádaigh, Conchúr M.. |
| Powder epoxy composites have several advantages for the processing of large composite structures, including low exotherm, viscosity and material cost, as well as the ability to carry out separate melting and curing operations. This work studies the mode I and mixed-mode toughness, as well as the in-plane mechanical properties of unidirectional stitched glass and carbon fibre reinforced powder epoxy composites. The interlaminar fracture toughness is studied in pure mode I by performing Double Cantilever Beam tests and at 25% mode II, 50% mode II and 75% mode II by performing Mixed Mode Bending testing according to the ASTM D5528-13 test standard. The tensile and compressive properties are comparable to that of standard epoxy composites but both the mode I... |
| Tipo: Text |
Palavras-chave: Toughened composites; Fracture toughness; Delamination. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00692/80371/83488.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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| Davies, Peter; Riou, Luc; Mazeas, Florence; Warnier, Philippe. |
| A study of thermoplastic matrix composites has been performed to investigate their use in underwater applications such as oceanography, submarine, and sub-sea offshore structures. This article first presents six candidate materials. Results from simple mechanical and seawater aging screening tests on flat specimens are then described. Glass/epoxy and carbon/epoxy composites are used as reference materials. Two materials emerged from this process, glass/PEI and carbon/PEEK. Cylinders of both were manufactured and subjected to hydrostatic pressure tests, and results are compared to those for glass/epoxy and carbon/epoxy cylinders of similar geometry. The carbon/PEEK material appeared most promising. It resisted pressures in excess of 90 MPa and was retained... |
| Tipo: Text |
Palavras-chave: Damage tolerance; Glass/PEI; Carbon/PEEK; Aging; Hydrostatic pressure; Cylinder. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-1037.pdf |
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| Chailleux, Emmanuel; Davies, Peter. |
| In this study the macroscopic analysis proposed by Schapery has been applied to model the non-linear viscoelastic and viscoplastic behaviour of polyester fibres. First, a special non-contact extensometry method has been developed in order to measure the fibre response without affecting the behaviour of these extremely anisotropic fibres. An accelerated identification method has then been developed. This enables a unique and independent set of parameters to be determined, which separate the reversible and non-reversible mechanisms responsible for measured strains. The model prediction for an arbitrary loading sequence corresponds closely to the measured strains. The model has been applied here at the yarn level but can equally well be used to predict rope... |
| Tipo: Text |
Palavras-chave: Viscoplastic; Viscoelastic; Polyester; Non linear; Model; Fibre. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-794.pdf |
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| Le Duigou, Antoine; Pillin, Isabelle; Bourmaud, Alain; Davies, Peter; Baley, Christophe. |
| The biocompostability of natural fibre-reinforced biopolymers, also known as biocomposites, makes them an attractive alternative to glass fibre-reinforced petrochemical polymers. The aim of this work is to study the capacity of flax/PLLA (poly(L-lactide)) biocomposite (20% and 30% fibres by weight) to be recycled. Mechanical properties were evaluated initially, and shown to be similar to those of glass/PP and superior to hemp/PP and sisal/PP composites. Then after repeated injection cycles tensile properties were shown to be conserved until the third cycle. Matrix degradation and fibre aspect ratio were followed using molecular weight measurements, thermal and rheological analyses, image analysis of sections and SEM fractography. These techniques revealed... |
| Tipo: Text |
Palavras-chave: Mechanical properties; Recycling; Flax fibres; PLLA. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6360.pdf |
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| Le Gac, Pierre-yves; Arhant, Mael; Davies, Peter; Muhr, Alan. |
| Natural rubber has been successfully used in a marine environment for many years. However, most applications involve low dynamic loadings. Due to the emergence of marine energy recovery, wave and tidal energy converters are being developed. In some such devices, rubbers are subjected to severe cyclic loadings, very different from their previous use in air or water. Such rubbers must therefore be qualified for long-term use in sea water with high fatigue loading. This paper presents a study using a new fatigue machine that allows the fatigue behaviour of rubber in sea water to be compared to that in air. The results show that the benefit of non-relaxing conditions on fatigue lifetime of natural rubber can be significantly reduced when it is used in sea... |
| Tipo: Text |
Palavras-chave: Natural Rubber; Water; Fatigue; Stabilisation. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00211/32240/32195.pdf |
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| Derombise, Guillaume; Van Schoors, Laetitia Vouyovitch; Davies, Peter. |
| Technora fibres are high performance aramid fibres which have been used in ropes and protective clothing for many years. They are also now being proposed as geotextiles for soil reinforcement. However, there is a lack of experience on the long-term behaviour of Technora fibres in an alkaline environment (lime-treated ground.). Consequently, aging studies have been performed under different conditions (deionised water, pH9 and pH11). Hydrolytic degradation has been evaluated by FTIR, viscometry, TGA, density measurements, SEM, and by tensile measurements. Some chain degradation and finish rearrangements have been highlighted, but Technora fibres retain their mechanical properties for all the conditions considered here. |
| Tipo: Text |
Palavras-chave: Aramids; Fibres; Technora; Hydrolysis; Long-term behaviour. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00002/11289/8052.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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| Choqueuse, Dominique; Davies, Peter; Perreux, Dominique; Sohier, L; Cognard, Jean Yves. |
| Ultra Deep offshore oil exploitation (down to 3000 meters depth) presents new challenges to offshore engineering and operating companies. Flow assurance and particularly the selection of insulation materials to be applied to pipe lines are of primary importance, and are the focus of much industry interest for deepwater applications. Polymeric and composite materials, particularly syntactic foams, are now widely used for this application, so the understanding of their behavior under extreme conditions is essential. These materials, applied as a thick coating (up to 10-15 cm), are subjected in service to: - high hydrostatic compression (up to 30 MPa) - severe thermal gradients (from 4°C at the outer surface to 150°C at the inner wall), and to high bending... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00039/15071/12632.pdf |
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| Baral, N.; Cartie, D. D. R.; Partridge, I. K.; Baley, C.; Davies, Peter. |
| This paper presents results from a test developed to simulate the water impact (slamming) loading of sandwich boat structures. A weighted elastomer ball is dropped from increasing heights onto rigidly supported panels until damage is detected. Results from this test indicate that honeycomb core sandwich panels, the most widely used material for racing yacht hulls, start to damage due to core crushing at impact energies around 550 J. Sandwich panels of the same areal weight and with the same carbon/epoxy facings but using a novel foam core reinforced in the thickness direction with pultruded carbon fibre pins, do not show signs of damage until above 1200 J impact energy. This suggests that these will offer significantly improved resistance to wave impact.... |
| Tipo: Text |
Palavras-chave: Honeycomb; Three-dimensional reinforcement; Impact behaviour; Mechanical testing. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00002/11311/7840.pdf |
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| Registros recuperados: 131 | |
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