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| Registros recuperados: 131 | |
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| Le Guen-geffroy, Antoine; Le Gac, Pierre Yves; Habert, B.; Davies, Peter. |
| This paper shows how physical ageing and plasticization processes are coupled in an amine-based epoxy. The study combines several ageing conditions including thermal ageing in the dry state (from 40 to 60 °C), ageing in a humid environment (RH 50% and RH 75%) as well as immersion in seawater at several temperatures from 15 to 40 °C. First results are presented to highlight that the two processes (physical ageing and plasticization) both occur when the epoxy is immersed in water. A step-by-step approach is then used to evaluate how the plasticization process induced by the presence of water is affected by physical ageing and vice versa. It appears that the plasticization process, which leads to a large decrease in maximum stress under tensile loading, is... |
| Tipo: Text |
Palavras-chave: Epoxy; Physical ageing; Water; Plasticization. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00512/62319/66717.pdf |
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| Baral, N; Davies, Peter; Baley, C; Bigourdan, Benoit. |
| This paper presents a study of the delamination resistance Of unidirectional carbon fibre reinforced epoxy composites manufactured from prepreg for racing yacht mast applications. Fibre modulus has been varied from 290 to 640 GPa. Two manufacturing methods, oven cure under vacuum and autoclave, were used to produce samples. Results show that delamination resistance tinder mode I and mixed mode loading decreases as fibre modulus increases. The manufacturing route affects G, values by modifying interlaminar layer geometry but does not change the trend of lower toughness with increasing fibre modulus. For the pitch composites crack propagation is observed within the fibres, in addition to more usual matrix and interface cracking. For the very high modulus... |
| Tipo: Text |
Palavras-chave: Mixed mode; Fracture toughness; Polymers; Carbon fibres; Delamination. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-3772.pdf |
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| Derombise, Guillaume; Van Schoors, Laetitia Vouyovitch; Messou, Marie-fleur; Davies, Peter. |
| Aramid fibers are high-performance materials which have been used in ropes and protective clothing for many years. They are also now being proposed in geo-textiles for ground reinforcement. The influence of the surface finish composition and content has been studied in the field of cables and textiles, but there is no published data concerning the effect of a finish treatment on the hydrolytic degradation. Aramid fibers with different finish contents have been aged in an alkaline environment. The degradation has been identified by FTIR, viscosimetry, TGA, SEM, and tensile tests. For Technora fibers, the presence of finish appears to limit the tensile strength loss of aramid fibers at pH 11 by limiting abrasion, as well as bulk and surface degradation. For... |
| Tipo: Text |
Palavras-chave: Aramids; Fibers; Aging; Finish; Hydrolysis. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00006/11702/8987.pdf |
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| Cognard, Jean-yves; Sohier, Laurent; Davies, Peter; Gineste, Bernard. |
| The objective of this study is to define a reliable tool for dimensioning of adhesively bonded assemblies, particularly for marine and underwater applications. A modified “Arcan” fixture, suited for the study of the behavior of bonded metal-metal assemblies, was developed in order to focus on the analysis of the behavior of the adhesive in thin films. To analyze the kinematics of the deformation of the adhesive joint non-contact extensometry techniques were employed. Thus various characteristics of the non-linear behavior of the adhesive were observed. The first results obtained for mixed assemblies (steel, aluminium, composite substrates) show similar behaviour of the adhesive using the proposed procedure. Furthermore, quality controls by DSC, and studies... |
| Tipo: Text |
Palavras-chave: Ssemblages collés; Modélisation; Essais; Comportement non-linéaire; Composites; Adhesive bonding; Model; Tests; Non linear behaviour; Composite. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00480/59156/61785.pdf |
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| Martin, Nicolas; Mouret, Nicolas; Davies, Peter; Baley, Christophe. |
| The flax quality required for composite applications is not yet well established. Retting is one of the steps that are not well defined for these applications, and is a critical parameter during flax production. In this study, the influence of the degree of retting of flax on the properties of short flax fiber/polypropylene composites has been assessed. First, the degree of retting of gradually retted flax was measured by both qualitative and quantitative experimental techniques. In addition, water sorption studies were performed. Furthermore, tensile tests were carried out on both single fiber and injected composite materials. The microstructure of the composites was analyzed by scanning electron microscopy and X-ray microtomography. Single fiber and... |
| Tipo: Text |
Palavras-chave: Flax fibers; Dew-retting; Composite materials; Polypropylene; Injection molding. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00160/27076/25475.pdf |
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| Le Guen-geffroy, Antoine; Le Gac, Pierre-yves; Diakhate, Malick; Habert, Bertrand; Davies, Peter. |
| Composite propellers are a major new development in the marine transport industry. The use of composite materials in seawater turbines is also of great interest to the marine renewable energy industry. Those systems present similarities being both constantly immersed in seawater, under fatigue loadings, of large dimensions, and they are often designed using Carbon Fibre Reinforced Polymer (CFRP). Previous studies have shown sensitivity of some composite materials to the seawater environment mainly in the quasi-static loading domain. However, investigations now need to be performed on the behaviour of CFRP under seawater environment and fatigue loadings. In this study, CFRP samples were aged in natural seawater until saturation, in order to investigate the... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00441/55262/56756.pdf |
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| Bordes, Melanie; Davies, Peter; Cognard, J. -y.; Sohier, L.; Sauvant-moynot, V.; Galy, J.. |
| This study is concerned with the development of a tool to predict the long term behaviour of adhesively bonded steel joints aged in sea water. First, diffusion kinetics and the mechanisms governing the degradation of mechanical properties of an epoxy adhesive are described. These two sets of data were used in a Coupled finite element (FE) analysis to determine the stress state in double lap shear (DLS) specimens before and after aging. However, subsequent tests on DLS specimens indicated an adhesive and not cohesive failure mode, so this approach could not be used to predict failure in the present case without introducing an interfacial damage parameter. A second approach was therefore employed, in which modified Arcan samples were designed in order to... |
| Tipo: Text |
Palavras-chave: Coupling; Finite element stress analysis; Aging; Durability. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6968.pdf |
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| Ghoreishi, Seyed Reza; Cartraud, Patrice; Davies, Peter; Messager, Tanguy. |
| Synthetic fiber ropes are characterized by a very complex architecture and a hierarchical structure. Considering the fiber rope architecture, to pass from fiber to rope structure behavior, two scale transition models are necessary, used in sequence: one is devoted to an assembly of a large number of twisted components (multilayered), whereas the second is suitable for a structure with a central straight core and six helical wires (1 + 6). The part I of this paper first describes the development of a model for the static behavior of a fibrous structure with a large number of twisted components. Tests were then performed on two different structures subjected to axial loads. Using the model presented here the axial stiffness of the structures has been... |
| Tipo: Text |
Palavras-chave: Testing; Analytical model; Multilayered structures; Aramid; Yarn; Fiber rope. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2595.pdf |
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| Simeone, M; Davies, Peter. |
| In the last two decades, the Finite Element Method has been growing as a powerful tool for the structural analysis of the ship hull, but in nautical construction the use of this method has been related mainly to steel or aluminium hulls. In a metallic structure the material is homogeneous and isotropic and the plate, or the stiffened plate, behaves as an orthotropic plate, which means orthogonally anisotropic with three mutually perpendicular planes of symmetry; on the contrary, when considering a composite hull panel the scheme ought to be different, because there arise two different problems, which ensue from the structural characteristics of the composite sandwich panel. Firstly, the Element Stiffness Matrix must take into account the natural anisotropy... |
| Tipo: Text |
Palavras-chave: Ship technology; Ship design; Ship hulls; Composite materials; Coque en composite; Sandwich; Eléments finis. |
| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/1992/acte-1072.pdf |
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| Perrot, Yves; Baley, C; Grohens, Y; Davies, Peter. |
| Composites based on glass fiber reinforced low styrene emission polyester resins have been widely used over the last 10 years, in order to meet increasingly strict safety regulations, particularly in the pleasure boat industry. Previous studies of their mechanical properties suggested that although these resins are generally more brittle than traditional orthophthalic polyester resins this did not adversely affect the properties commonly used for quality control (short beam shear and tensile failure strength of mat reinforced composites). In the present paper results from a more detailed study of damage behaviour are presented. Tests include fracture toughness (K (Ic) ) tests on resins, fibre/matrix interface energy, detection of composite damage... |
| Tipo: Text |
Palavras-chave: Interface properties; Damage initiation; Styrene emission; Unsaturated polyester; Glass fibers. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2316.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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| Cognard, J. Y.; Creac'Hcadec, R.; Maurice, J.; Davies, Peter; Peleau, Michel; Da Silva, L. F. M.. |
| Generally, adhesives are viscoelastic-plastic materials, for which the development of viscosity and plasticity varies depending on the type of adhesive and the stress state. Various models exist to represent the yield surface, or the so-called elastic limit, taking into account the two stress invariants, hydrostatic stress and von Mises equivalent stress. Moreover, to develop precise pressure-dependent constitutive models, it is necessary to have a large experimental database in order to accurately represent the adhesive strains which are strongly dependent on the tensile-shear loading combination. Under quasi-static loadings, for a given strain rate range viscous effects can be neglected, but only a few experimental results are available to model the... |
| Tipo: Text |
Palavras-chave: Adhesive testing; Non-linear behaviour; Modelling; Hydrostatic stress; Finite element analysis. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00018/12903/10396.pdf |
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| Le Gac, Pierre-yves; Broudin, Morgane; Roux, Gérard; Verdu, Jacques; Davies, Peter; Fayolle, Bruno. |
| Tensile properties and crack propagation properties, especially critical strain energy release rate in mode I, GIC, have been used to investigate fracture properties of elastomers and their relationships with microstructure. These investigations were mainly based on a series of comparisons: first, the behaviour of polychloroprene rubber (CR), undergoing stress hardening due to strain induced crystallization (SIC) and oxidative crosslinking (OCL) was compared with that of chlorinated polyethylene (CPE), which undergoes SIC but not OCL, and with a polyurethane based on hydroxyl terminated polybutadiene (PU) which undergoes OCL but not SIC. Comparisons were also made on CR between fracture behaviour at ambient temperature, where SIC occurs and at 100°C where... |
| Tipo: Text |
Palavras-chave: Fracture; Rubber; Oxidation. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00184/29546/27872.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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| Cartie, D; Davies, Peter; Peleau, Michel; Partridge, I.k.. |
| The use of composites for deep sea applications requires a thorough understanding of the behaviour of these materials. While several studies have examined the influence of pressure on in-plane properties few data are available for the interlaminar fracture behaviour. This paper presents results from such tests performed in a specially designed pressure vessel mounted on a standard test machine, which allows pressures up to 1000 bars (100 MPa) to be applied during mechanical testing. Mode I and Mode 11 tests have been performed on a unidirectional IM7/977-2 carbon/epoxy composite. No effect of pressure was noted on Mode I fracture toughness. A data reduction scheme has been developed for Mode 11 loading and an increase in Glic with increasing pressure was... |
| Tipo: Text |
Palavras-chave: Fracture; Mechanical properties; Fracture toughncss. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1680.pdf |
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| Registros recuperados: 131 | |
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