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Registros recuperados: 116
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3D Modeling of the Elastic-Plastic Behavior of Thin Aeronautical Adhesive Films Suited for a Wide Range of Tensile/Compression-Shear Loads ArchiMer
Maurice, Julien; Creac'Hcadec, Romain; Cognard, Jean-yves; Davies, Peter; Meirinhos, Georges; Mahdi, Stephane.
Adhesive bonding is an interesting structural assembling technique for weight saving in modern commercial aircraft, in which the use of composites materials is increasing. In order to meet both optimization and respect of safety conception constraints, the development of accurate numerical strategies is required. Thus, improvement in the experimental characterization and in the design of reliable numerical tools for bonded assemblies is necessary. This paper presents the characterization of the elastic-plastic behaviour of four aeronautical adhesive films, consisting of two epoxy-based resins supported by two types of carrier. The characterization over a wide range of monotonic proportional tensile-shear loads is performed using a modified Arcan test...
Tipo: Text Palavras-chave: Aeronautical; Mechanical properties of adhesives; Numerical modeling.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00142/25317/26067.pdf
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A modified Arcan test to analyze the behavior of composites and their assemblies under out-of-plane loadings ArchiMer
Cognard, J. Y.; Sohier, L.; Davies, Peter.
Composite materials are a key element in weight reduction strategies, so the analysis of the mechanical behavior of assemblies of composite modules is of great importance. Failure initiation in bonded assemblies involving composites is often associated with crack initiation in the adhesive or delamination of the composite plies close to the adhesive joint, caused by interlaminar or through-thickness stresses. Thus, the analysis of the behavior of composites and their assemblies under out-of-plane loadings is necessary in order to optimize such structures. However, few experimental devices are proposed in the literature and they often require thick composite specimens which are not representative of most industrial applications. This paper describes the use...
Tipo: Text Palavras-chave: Laminates; Adhesion; Stress concentrations; Mechanical testing.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00026/13740/11039.pdf
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A multi-scale study of the interface between natural fibres and a biopolymer ArchiMer
Le Duigou, Antoine; Baley, Christophe; Grohens, Yves; Davies, Peter; Cognard, Jean Yves; Creach Cadec, Romain; Sohier, Laurent.
A significant recent development in the composite field is the appearance of biocomposites (biopolymers reinforced by plant fibres) which combine mechanical performance and low environmental impacts. However, to replace conventional composites a significant effort is needed to understand their mechanical behaviour under complex loading (both in-plane and out-of-plane). The interfacial behaviour (fibre/matrix) of these materials also requires particular attention in order to optimize mechanical properties. With this aim modified Arcan, transverse tension and microdroplet debonding tests have been performed on flax reinforced PLLA biocomposites, as very few data of this type are available. The out-of-plane tensile and tensile-shear properties of these...
Tipo: Text Palavras-chave: A natural fibre composites; B interfacial properties; B out-of-plane properties; B microbond test.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00197/30857/29222.pdf
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A non-linear viscoelastic viscoplastic model for the behaviour of polyester fibres ArchiMer
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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A preliminary evaluation of matricaria maritimum fibres for polymer reinforcement ArchiMer
Davies, Peter; Bourmaud, A.; Pajot, A.; Baley, C..
This short communication describes results from a preliminary characterization of the dimensions and mechanical properties of matricaria maritimum fibres. The aim is to develop a complementary industrial application of these plants, which are grown along the coast mainly for pharmaceutical use. The fibres are shown to be of small diameter, 5-10 mu m, and tubular in form. Nano-indentation on fibres and tensile tests on fibre bundles provide an indication of the mechanical behaviour of these fibres, which are similar to those of sisal (leaf fibre) and miscanthus (grass fibre), and may be interesting for reinforcement of polymer matrix composites.
Tipo: Text Palavras-chave: Natural fibre; Nano-indentation; Tensile properties.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00042/15369/12790.pdf
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A review of synthetic fiber moorings for marine energy applications ArchiMer
Davies, Peter; Weller, Sam D.; Johanning, Lars; Banfield, Stephen J..
Many marine renewable energy (MRE) conversion systems including wave, floating wind, Ocean Thermal Energy Conversion (OTEC) and some tidal energy devices, are moored in place. The choice of mooring system is critical as it directly affects installation, energy take-off, and long term reliability, and hence has a significant influence on costs. Installation has been estimated to account for 27% of lifetime cost for a tidal turbine [1]. This is an area where the other marine industries, notably offshore oil and gas, have extensive experience, but the high energy regions in which MRE devices are deployed pose particular installation difficulties and operating conditions. There has been a strong movement towards replacing steel with synthetic fiber ropes...
Tipo: Text
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00251/36220/34771.pdf
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A status report on delamination resistance testing of polymer-matrix composites ArchiMer
Brunner, A; Blackman, B; Davies, Peter.
The development of fracture mechanics test methods for the determination of delamination resistance or fracture toughness of fiber-reinforced, polymer-matrix composites is an active area of research. The emphasis in this review is on standardisation of test methods. Recent developments leading towards new standardized test procedures will be presented, complementing and updating earlier reviews. (c) 2007 Elsevier Ltd. All rights reserved.
Tipo: Text Palavras-chave: Review; Standards; Test procedure; Polymer matrix composites; Delamination resistance; Fracture toughness.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-3950.pdf
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A study of the non-linear behaviour of adhesively-bonded composite assemblies ArchiMer
Cognard, Jean Yves; Davies, Peter; Sohier, S; Creac' Hcadec, R.
The objective of this study is to define a reliable tool for dimensioning of adhesively bonded assemblies, particularly for marine and underwater applications. This paper presents experimental and numerical results, which describe the non-linear behaviour of an adhesive in a bonded assembly for various loadings. A modified Arcan fixture, well-suited for the study of the behaviour of bonded metal-metal assemblies, was developed in order to focus on the analysis of the behaviour of the adhesive in thin films. The edge effects are minimised by using an appropriate design of the substrates so that experimental results give reliable data. To analyze the kinematics of the deformation of the adhesive joint non-contact extensometry techniques were employed. Thus,...
Tipo: Text Palavras-chave: Non linear behaviour; Finite element; Arcan fixture; Marine structures; Composite; Adhesion.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-2079.pdf
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A viscoelastic-viscoplastic model to describe creep and strain rate effects on the mechanical behaviour of adhesively-bonded assemblies ArchiMer
Ilioni, Alin; Badulescu, C.; Carrere, N.; Davies, Peter; Thevenet, D..
Most of the adhesives used in the marine industry are polymers with a mechanical behaviour which is strongly influenced by the strain rate. Therefore, it is important to predict with accuracy their viscous behaviour. To describe their mechanical behaviour in a bonded joint, a viscoelastic-viscoplastic constitutive law is proposed here. The viscous effects on the elastic behaviour is described using a spectral distribution, which divides the viscous strain as the sum of the strains of several viscous mechanisms, each of them with a different characteristic time and weight. The viscoplastic component of the model permits a better description of the strong non-linear behaviour of the adhesives. The parameters of the constitutive law are obtained using an...
Tipo: Text Palavras-chave: Epoxides; Mechanical properties of adhesives; Creep / mechanical relaxation.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00415/52651/53507.pdf
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Accelerated ageing and lifetime prediction of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in distilled water ArchiMer
Deroine, Morgan; Le Duigou, Antoine; Corre, Yves-marie; Le Gac, Pierre-yves; Davies, Peter; Cesar, Guy; Bruzaud, Stephane.
Accelerated ageing was performed in distilled water at different temperatures (25, 30, 40 and 50°C) on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), which is a biodegradable biopolymer, in order to estimate its lifetime in aqueous environment. In a first part, degradation mechanisms were followed by gravimetry, tensile tests and steric exclusion chromatography. Both immersion and relative humidity have been examined. In a second part, the strain at break was used as an indicator for lifetime prediction with an Arrhenius extrapolation. The study revealed the presence of only one irreversible degradation mechanism, i.e. hydrolytic degradation, which is temperature dependant. So, within the approach assumptions, the lifetime in distilled water of PHBV...
Tipo: Text Palavras-chave: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate); Accelerated ageing; Hydrothermal degradation; Lifetime prediction.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00203/31396/29785.pdf
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Accelerated ageing of polylactide in aqueous environments: Comparative study between distilled water and seawater ArchiMer
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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Accelerated ageing of polyurethanes for marine applications ArchiMer
Davies, Peter; Evrard, Guy.
Polyurethanes are frequently used in underwater applications. They are required to resist the marine environment over long periods of immersion but the multiplicity of resin formulations makes material selection difficult. Accelerated tests are essential to guarantee long term integrity. This paper presents results from an experimental study in which polyurethane samples of two hardnesses, 40 and 90 Shore A, have been subjected to immersion in artificial sea water for periods up to two years at temperatures from 50 to 100 degrees C. In parallel samples have been immersed at sea in the Brest Estuary for up to five years. Mechanical properties have been measured on tensile specimens after ageing. The accelerated test results and FTIR analysis indicate that...
Tipo: Text Palavras-chave: Accelerated test; Sea water; Ageing; Marine; Polyurethane.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2822.pdf
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An empirical model to predict the lifetime of braided HMPE handling ropes under cyclic bend over sheave (CBOS) loading ArchiMer
Davies, Peter; Francois, M; Lacotte, Nicolas; Vu, Thanh Do; Durville, Damien.
Repeated bending over sheaves is one of the main causes of failure of synthetic fibre ropes used in marine operations. There are few published results available and even fewer models allowing lifetime to be estimated. A large new set of data from cyclic bend over sheave (CBOS) tests on 250 kN break load braided HMPE synthetic ropes is presented first, both tests to failure and interrupted tests followed by residual strength measurements. These data are analysed in order to propose an empirical lifetime model. This is identified using constant load tests, then evaluated for variable load sequences. A methodology to include rope lifetime prediction in handling system design is then discussed.
Tipo: Text Palavras-chave: Fibre rope; Bending; Sheave; Abrasion; Fatigue.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00251/36215/34775.pdf
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An experimental study of water diffusion in carbon/epoxy composites under static tensile stress ArchiMer
Humeau, Corentin; Davies, Peter; Jacquemin, Frederic.
The coupling between tensile stress and water diffusion in composites represents a major issue in many marine applications. Even if these two behaviours are well documented as separate subjects, there are still very few data on fully coupled mechanisms. The aim of this study is to understand what governs the coupled behaviour, by investigating the water diffusion in carbon/epoxy. The coupling is first evaluated on neat resin samples to characterise the matrix behaviour. Then the study focuses on composites with two types of woven fibre orientation: one at ±45°, in order to understand the coupling effects on materials loaded away from the reinforcement direction and another quasi-isotropic to obtain properties along the fibres. For each material the same...
Tipo: Text Palavras-chave: Composite; Moisture diffusion; Static tensile stress; Coupled behaviour.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00416/52788/53687.pdf
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Analyse du cycle de vie d’un biocomposite ArchiMer
Le Duigou, A.; Davies, Peter; Baley, C..
In addition to the impact on climate change resulting from the use of non renewable resources [1], the depletion of existing fossil fuel sources is inevitable. A major change of strategy is required. This article presents an analysis of a Flax fibre/PLLA biocomposite life cycle compared to common glass fibre reinforced polyester composites from manufacturing to mechanical design and end-of-life. Environmental impacts have been assessed by Standardized method called Life Cycle Analysis (ISO 14044). Flax fibre/PLLA biocomposites manufactured by film stacking have, for similar mass, tensile modulus close to that of Glass/Polyester. Besides being compostable at end of life, biocomposites have been proved to be recyclable which makes it possible to keep the...
Tipo: Text Palavras-chave: Biocomposites; Fibres végétales; Recyclage; Analyse de cycle de vie; Biocomposites; Vegetal fibres; Recycling; Life cycle analysis.
Ano: 2010 URL: https://archimer.ifremer.fr/doc/00480/59149/61778.pdf
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Analysis of the Influence of Hydrostatic Stress on the Behaviour of an Adhesive in a Bonded Assembly ArchiMer
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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Analysis of the moisture effect on the mechanical behaviour of an adhesively bonded joint under proportional multi-axial loads ArchiMer
Arnaud, N.; Creac'Hcadec, R.; Cognard, J. Y.; Davies, Peter; Le Gac, Pierre-yves.
The objective of the study is to identify the 3D behaviour of an adhesive in an assembly, and to take into account the effect of ageing in a marine environment. To that end, three different tests were employed. Gravimetric analyses were used to determine the water diffusion kinetics in the adhesive. Bulk tensile tests were performed to highlight the effects of humid ageing on the adhesive behaviour. Modified Arcan tests were performed for several ageing times to obtain the experimental database which was necessary to identify constitutive models. A Mahnken-Schlimmer type model was determined for the unaged state according to a procedure developed in a previous study. This identification used inverse techniques. It was based on the unaged modified Arcan...
Tipo: Text Palavras-chave: Water resistance; Arcan test; Ageing; Epoxides; Finite-element stress analysis; Durability.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00277/38788/37557.pdf
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Analysis of the nonlinear behavior of adhesives in bonded assemblies - Comparison of TAST and Arcan tests ArchiMer
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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Analytical modeling of synthetic fiber ropes. Part II: A linear elastic model for 1+6 fibrous structures ArchiMer
Ghoreishi, Seyed Reza; Davies, Peter; Cartraud, Patrice; Messager, Tanguy.
In part I of this study it was shown that, to model synthetic fiber ropes, two scale transition models can be used in sequence. The first model (continuum model) has been presented in the part I and the present paper examines the behavior of a fibrous structure consisting of 6 helicoidal strands around a central core (1 + 6 structure). An analytical model will be presented which enables the global elastic behavior of such a cable under tension-torsion loading to be predicted. In this model, first, the core and the strands are described as Kirchhoff-Love beams and then the traction-torsion coupling behavior is taken into account for both of them. By modeling the contact conditions between the strands and the core, with certain assumptions, it is possible to...
Tipo: Text Palavras-chave: Testing; Analytical model; Aramid; Wire; Simple strand; Fiber rope.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2596.pdf
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Analytical modeling of synthetic fiber ropes subjected to axial loads. Part I: A new continuum model for multilayered fibrous structures ArchiMer
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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