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| Registros recuperados: 131 | |
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| Davies, Peter; Bunsell, A. R.; Chailleux, Emmanuel. |
| Poly(p-phenylene benzobisoxazole) (PBO) fibres are finding increasing applications on account of their exceptional stiffness and strength. This article presents results from tests on single PBO filaments, to characterize their intrinsic behaviour under quasi-static and cyclic tensile loading. Scanning electron microscopy is used to show the fibrillation mechanism leading to failure. Results are compared to data for polyester, aramid and high modulus polyethylene fibres. PBO fibres show shorter fatigue lifetimes than the other fibres when maximum stress is expressed as a percentage of quasi-static break load, but the absolute stress values applied are much higher for an equivalent lifetime. |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00016/12688/9625.pdf |
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| Deroine, Morgan; Le Duigou, Antoine; Corre, Yves-marie; Le Gac, Pierre-yves; Davies, Peter; Cesar, Guy; Bruzaud, Stephane. |
| Pollution of nature by plastics is a major environmental problem and the challenge for the future is to manage the lifetime of polymers better. The aim of this study is to establish a baseline on degradation mechanism and degradation kinetics for lifetime prediction of polylactide (PLA) in a marine environment. The ageing of PLA was accelerated by raising temperature in distilled water, filtered and renewed seawater and natural seawater. Samples were immersed in distilled water for six months at different temperatures (25, 30, 40 and 50°C) in order to evaluate the influence of temperature on PLA degradation kinetics and to predict lifetime. Then, samples were immersed in seawater both in the laboratory and at sea, in order to compare the effects of... |
| Tipo: Text |
Palavras-chave: PLA; Accelerated ageing; Hydrothermal ageing; Degradation. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00173/28376/26689.pdf |
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| Loaec, Henri; Morandeau, Fabien; Meillat, Marc; Davies, Peter. |
| There are different approaches to selectivity, including increasing cod-end mesh size, square mesh panels and rigid grids. Selectivity grids have traditionally been produced to be as rigid as possible to maintain spacing but this can result in heavy, expensive grids, handling problems and brittleness. This paper presents an alternative approach using flexible polyurethane polymers to produce lightweight inexpensive grids with much improved damage tolerance and ease of handling, which also possess interesting selectivity characteristics. The material selection, design and development tests are described first, then preliminary sea trial results are presented. A flexible grid with a 20 mm spacing between bars performed successfully and enabled a reduction in... |
| Tipo: Text |
Palavras-chave: Damage resistance; Polyurethane; Nephrops; Grid; Size selection; By catch; Selectivity. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1690.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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| Arhant, Mael; Briancon, Christophe; Burtin, Christian; Davies, Peter. |
| The composite materials used at sea are today nearly all based on thermoset resins (polyester, epoxy). However, there is an increasing number of thermoplastic matrix polymers available on the market (PP, PA, PPS, PEEK…), which offer possibilities for forming by local heating, attractive mechanical properties and the potential for end of life recycling. The aim of this study was to design, manufacture and test thermoplastic composite pressure vessels for 4500 meter depth, in order to establish a technical, economic and ecological assessment of the use of these materials to replace traditional composites underwater. First, finite element calculations have been carried out to optimize the stacking sequence with respect to the external pressure and buckling... |
| Tipo: Text |
Palavras-chave: Thermoplastic; Polyamide; Carbon fibres; Buckling; Implosion. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00476/58742/61268.pdf |
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| Perrot, Y; Davies, Peter; Kerboul, Andre; Baley, C. |
| Delays between lamination of structures and secondary bonding are common in boatbuilding. This paper presents results from an experimental study of the influence of manufacturing procedure on the bond strength of unidirectional glass fibre reinforced polyester composites. Continuously laminated panels are taken as the reference and compared with panels overlaminated after delays of one week with and without peel ply protection. A standard polyester and low styrene DCPD formulation were tested. ILSS testing is shown not to be sensitive to the procedure but crack propagation tests show very large differences in mode I fracture energy. A small drop in fracture energy is measured for a delay of one week between lamination of the first and second halves of the... |
| Tipo: Text |
Palavras-chave: Mode I; ILSS; Peel ply; Lamination procedure; Low styrene content resins; Glass/polyester composites. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4557.pdf |
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| Davies, Peter; Baley, C; Loaec, Henri; Grohens, Y. |
| This paper presents results from a study of the influence of surface preparation on the mechanical performance of overlaminated polyester composites. Panels of 16 woven glass plies have been prepared in two halves by hand lay-up. After the first 8 plies were laminated the surface was either protected by a peel ply or left in air. The overlamination of the second half of the composite thickness was completed after different periods and interlaminar shear, flexure and mode I fracture specimens were tested. The results enabled the influence of the delay and the surface condition to be related to mechanical performance. Surfaces protected with peel plies show very low G(Ic) propagation energy release rates. Results are compared to those from continuous... |
| Tipo: Text |
Palavras-chave: Mode I; Woven; Peel ply; Glass/polyester; Overlamination; Interlaminar. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-1034.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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| Deroine, Morgan; Le Duigou, Antoine; Corre, Yves-marie; Le Gac, Pierre-yves; Davies, Peter; Cesar, Guy; Bruzaud, Stephane. |
| The aim of this study is to establish a baseline for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) lifetime prediction in a marine environment, by means of mechanical and physico-chemical characterization of specimens immersed in continuously renewed and filtered natural seawater in the laboratory at different temperatures (4, 25 and 40°C). Samples were also aged at sea in Lorient harbour in order to compare laboratory and natural degradation mechanisms and kinetics. Due to its morphology, hydrolysis of PHBV in natural seawater is quite slow, and samples were observed to undergo preferentially an enzymatic surface degradation. Increasing the aging temperature in the laboratory promotes the water uptake and causes hydrolysis. As two degradation... |
| Tipo: Text |
Palavras-chave: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate); Accelerated ageing; Hydrothermal degradation; Seawater. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00188/29972/28425.pdf |
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| Davies, Peter; Le Gac, Pierre-yves; Le Gall, Maelenn. |
| A new matrix resin was recently introduced for composite materials, based on acrylic resin chemistry allowing standard room temperature infusion techniques to be used to produce recyclable thermoplastic composites. This is a significant advance, particularly for more environmentally-friendly production of large marine structures such as boats. However, for such applications it is essential to demonstrate that composites produced with these resins resist sea water exposure in service. This paper presents results from a wet aging study of unreinforced acrylic and glass and carbon fibre reinforced acrylic composites. It is shown that the acrylic matrix resin is very stable in seawater, showing lower property losses after seawater aging than those of a... |
| Tipo: Text |
Palavras-chave: Acrylic; Thermoplastic; Infusion; Seawater; Immersion. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00347/45815/45541.pdf |
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| Cognard, J; Creac' Hcadec, R; Sohier, L; Davies, Peter. |
| This paper describes a study in which the shear behavior of a structural epoxy adhesive has been measured using the standard thick adherend shear test (TAST) specimen and a modified Arcan test A. numerical study of the TAST test taking into account the nonlinear behavior of the adhesive and the finite deformations of the adhesive joint, shows that there is a localization of plastic zones close to the adhesive-substrate interface near the free edge of the adhesive. Experimental tests carried out with steel and aluminum substrates and with various adhesives also show that failure initiates in this region. These edge effects in the TAST fixture can lead to an incorrect analysis of the behavior of the adhesive (for instance, underestimation of the shear stress... |
| Tipo: Text |
Palavras-chave: Adhesive testing; Mechanical properties of adhesives; Stress distribution; Epoxy/epoxides. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4646.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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| Maurin, R; Davies, Peter; Baral, N; Baley, C. |
| In this study the transverse modulus of three high modulus (M40, M46 and K63712) carbon fibres has first been measured directly by nano-indentation measurements. Transverse tensile tests on unidirectional epoxy composites were then performed, and the comparison was made between transverse fibre properties from indentation and those needed to obtain the measured transverse composite modulus using micromechanics expressions. The latter tended to underestimate values from indentation, by up to 36%, and reasons for this are discussed. Values of transverse fibre modulus determined by both methods decrease as longitudinal fibre modulus increases. |
| Tipo: Text |
Palavras-chave: Transverse tensile; Nano indentation; Epoxy; Carbon fibre. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4502.pdf |
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| Maurin, Romain; Baley, Christophe; Cartie, Denis D. R.; Davies, Peter. |
| This paper describes results from tests to examine the influence of through-thickness pinning on in-plane shear behaviour, measured by tensile loading of +/- 45A degrees specimens. Samples were produced by both aeronautical and marine manufacturing processes. As few previous studies have investigated pinning of marine composites these were also subjected to out-of-plane shear delamination tests. For both carbon/epoxy laminates the pins reduce the apparent in-plane shear modulus and strength. Pins modify the strain field measured by full-field image analysis, and slow damage development. A new damage mechanism, transverse pin cracking, was observed. |
| Tipo: Text |
Palavras-chave: Z-pinning; Shear; Mode II; Damage; Acoustic emission. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00113/22390/20186.pdf |
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| Le Gac, Pierre Yves; Roux, Gerard; Verdu, Jacques; Davies, Peter; Fayolle, Bruno. |
| Thermal oxidation in air at atmospheric pressure, in the 80-140°C temperature range and in oxygen at 100°C in the 0.02-3 MPa pressure range, of unvulcanized, unstabilized, unfilled polychloroprene (CR) has been characterized using FTIR and chlorine concentration measurement. The kinetic analysis was focused on double bond consumption. A mechanistic scheme involving unimolecular and bimolecular hydroperoxide decomposition, oxygen addition to alkyl radicals, hydrogen abstraction on allylic methylenes, alkyl and peroxyl additions to double bonds and terminations involving alkyl and peroxy radicals was elaborated. The corresponding rate constants were partly extracted from the literature and partly determined from experimental data using the kinetic model... |
| Tipo: Text |
Palavras-chave: Polychloroprene; Oxidation; Radical chain; Kinetics. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00199/31010/29413.pdf |
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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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| Ilioni, Alin; Le Gac, Pierre-yves; Badulescu, Claudiu; Thévenet, David; Davies, Peter. |
| This article describes an approach to predict the behaviour of an epoxy adhesive in bulk form in a marine environment. First, the material, the experimental conditions and the predictive framework are described. Then the experimental results are presented, which indicate that the effects on yield stress of either a uniform water profile or elevated testing temperature can be shown to be equivalent when plotted versus T-Tg. Moreover, a discussion of these results shows how they can be used to predict changes in the mechanical properties of the adhesive. Prediction results for yield stress are in good agreement when they are compared with experimental results for the case of a water profile gradient, in order to evaluate the relevance and limitations of the... |
| Tipo: Text |
Palavras-chave: Epoxide; Water ageing; Glass transition temperature; Mechanical properties of adhesives; Plasticisation. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00419/53052/54052.pdf |
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| Davies, Peter; Verbouwe, W.. |
| Basalt fibres offer potential for use in marine structures, but few data exist to evaluate the influence of seawater immersion on their mechanical behaviour. This paper provides the results from a study in which basalt fibre reinforced epoxy composites were aged in natural seawater at different temperatures. Tests were performed under quasi-static and cyclic loading, first in the as-received state then after saturation in natural seawater. Results are compared to those for an E-glass reinforced composite with the same epoxy matrix. They indicate similar mechanical performance for both materials after seawater saturation. |
| Tipo: Text |
Palavras-chave: Seawater; Aging; Fatigue; Basalt fibre; Epoxy; Unidirectional; Flexure. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00392/50385/51111.pdf |
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| Ghoreishi, S; Messager, T; Cartraud, P; Davies, Peter. |
| In the field of cable modeling, many models have been proposed to describe the mechanical behavior of simple straight strands under axial loading, and the predictions of these models have been compared to experimental data when available. However, the validity domain of these models has not been evaluated yet because the experimental results reported in the literature are very limited. This problem is addressed here, the results from nine linear elastic models of a 6 + 1 wire single layered strand (simple straight strand) subjected to static axial loads being compared with values from 3D finite element modeling. The analytical models are shown to give satisfactory estimations of the elastic stiffness constants for lay angles below 20 degrees. (C) 2007... |
| Tipo: Text |
Palavras-chave: Finite element; Analytical model; Wire; Strand; Cable. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-4206.pdf |
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| Registros recuperados: 131 | |
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