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| Registros recuperados: 131 | |
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| Boisseau, Amelie; Davies, Peter; Thiebaud, Frederic. |
| Composite material components will be an essential part of ocean energy recovery devices, and their long term durability in sea water must be guaranteed. Despite extensive experience for boat structures and wind turbines few data exist to design structures subjected to a combination of mechanical loads and sea water immersion. This paper presents the first results from an experimental study, performed jointly with fibre manufacturers, and a resin supplier, to fill this gap. The experimental study is completed by numerical modelling to simulate the coupling between water absorption and mechanical behaviour. Sea water ageing is shown to result in a drop in quasi-static mechanical properties and a change in flexural mode from compression to tension at longer... |
| Tipo: Text |
Palavras-chave: Composite material; Sea water ageing; Failure mechanism; Flexure; Tidal turbine. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00085/19578/17220.pdf |
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| Baley, Christophe; Gomina, Moussa; Breard, Joel; Bourmaud, Alain; Davies, Peter. |
| Flax fibres are a promising reinforcement in the development of biocomposites and are finding new applications in transport structures. However, there is a perceived problem with plant fibres related to the variability of the properties of these natural materials. This paper describes the factors which affect variability, from plant growth conditions to fibre sampling and testing. A large number of test results are presented (characterization of elementary fibres, bundles, assemblies of bundles, and unidirectional composites), and it is shown that provided fibre supply is carefully controlled, characterization procedures are appropriate, and manufacturing processes are optimal then excellent composite properties can be achieved with low variability. |
| Tipo: Text |
Palavras-chave: Flax fibre; Composite; Variability; Mechanical properties. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00593/70488/68656.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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| 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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| Davies, Peter; Arhant, Mael; Le Gac, Pierre Yves; Le Gall, Maelenn; Kemlin, Guillaume. |
| There are more than a thousand species of bamboo and some of these contain large amounts of fibres with attractive properties. However, the extraction of the fibres without damaging them is difficult, requiring energy and special equipment. One solution is to use the bamboo in the form of thin strips taken from fibre-rich regions of the plant, as done by the Cobratex company in an innovative process. These contain the fibres but they are protected from damage and keep their alignment. This paper presents the results from a study of bamboo strips, alone and in an infused composite. The influence of seawater immersion is investigated. The composite weight gain is high, around 25 %, but most of the water is in the natural canals of the wood. The influence of... |
| Tipo: Text |
Palavras-chave: Bamboo; Density; Mechanical properties; Wet aging. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00593/70534/68681.pdf |
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| Baley, Christophe; Kervoelen, Antoine; Lan, Marine; Cartie, Denis; Le Duigou, Antoine; Bourmaud, Alain; Davies, Peter. |
| Automated fibre placement (AFP) has been used to manufacture flax/polypropylene biocomposites for the first time. This required preparation of tape with a calibrated width from impregnated fibre sheets. The unidirectional tapes showed polymer-rich zones on the surface. During manufacture the polypropylene (PP) is melted locally with a laser. A consolidation step in a hot press is then required to reduce void content. The flax fibres, composed of polysaccharides, have limited thermal resistance so optimization of the thermal cycle is necessary, but subsequent characterization of mechanical behaviour showed no evidence of property loss in spite of an additional melting cycle. AFP appears to be a promising manufacturing method for biocomposites. |
| Tipo: Text |
Palavras-chave: Structural composites; AFP; Biocomposites; Flax; PP. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00307/41800/41009.pdf |
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| 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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| Lechat, C.; Bunsell, A. R.; Davies, Peter. |
| Ropes made of twisted polyester (PET) yarns have been replacing traditional steel ropes and chains as mooring lines for offshore platforms in deep-sea environments. In order to optimise rope manufacture and the design of mooring systems, a thorough understanding of the material's mechanical behaviour is necessary. Besides PET, other materials can also be considered such as PEN, as it also a polyester similar to PET but stiffer. This paper presents a study and comparison of PET and PEN fibres' mechanical behaviour, based on experiments carried out on single filaments. Both fibres show similar non-linear tensile behaviour, with an evolution of modulus in four steps. The same microstructural model is proposed for both fibres, based on microfibrils aligned... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00029/14062/11316.pdf |
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| Le Duigou, Antoine; Davies, Peter; Baley, Christophe. |
| The influence of wet aging on the behaviour of flax/epoxy micro-composites composed of single flax fibres embedded in epoxy micro-droplets has been studied. Interfacial shear strength has been examined by debonding the micro-droplets. The apparent interfacial shear strength decreases with immersion time in water, dropping rapidly during the first 15 min of immersion then stabilizing. Drying samples after short immersion periods allows recovery of properties, indicating a plasticization mechanism. For longer immersion times irreversible degradation is observed. Scanning electron microscopy reveals fibre surface peeling, indicating that an internal interface within the fibre is weaker than the fibre/matrix interface after aging. A simple descriptive model... |
| Tipo: Text |
Palavras-chave: Flax fibres; Environmental degradation; Fibre/matrix bond. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00137/24829/23101.pdf |
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| Davies, Peter; Germain, Gregory; Gaurier, Benoit; Boisseau, Amelie; Perreux, Dominique. |
| The long term reliability of tidal turbines is critical if these structures are to be cost-effective. Optimised design requires a combination of material durability models and structural analyses. Composites are a natural choice for turbine blades but there are few data available to predict material behaviour under coupled environmental and cycling loading. This paper addresses this problem, by introducing a multi-level framework for turbine blade qualification. At the material scale static and cyclic tests have been performed, both in air and in seawater. The influence of ageing in seawater on fatigue performance is then quantified and much lower fatigue lives are measured after ageing. At a higher level flume tank tests have been performed on three-blade... |
| Tipo: Text |
Palavras-chave: Composite; Fatigue; Ageing; Tidal turbine; Flume tank; Finite-element model. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00079/19053/20068.pdf |
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| Chevillotte, Yoan; Marco, Yann; Bles, Guilhem; Devos, Karel; Keryer, Mathieu; Arhant, Mael; Davies, Peter. |
| 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 oil and gas 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. In this paper yarn-on-yarn abrasion testing is used first to evaluate a new yarn coating. Significant lifetime enhancement was noted, so fatigue testing of ropes was then performed. Results confirm that excellent fatigue... |
| Tipo: Text |
Palavras-chave: Fatigue; Rope; Nylon; Mooring; Water; Floating wind turbine. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00607/71884/70609.pdf |
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| 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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| Le Duigou, Antoine; Bourmaud, Alain; Davies, Peter; Baley, Christophe. |
| Innovation in sailing yacht design must include current environmental concerns such as resource depletion and waste management. Indeed most of the materials used today are petro-based and cannot offer viable end of life treatment. Fully biodegradable natural fibre reinforced biopolymers are being increasingly studied as they offer high specific stiffness and low environmental footprint. However, their ageing mechanisms are still not well understood. The present article gives information on 2 years natural seawater aging effect on injection-molded Flax/PLA biocomposite. Biocomposites suffer from relatively high moisture absorption which is controlled by the vegetal fibres. Simple rules of mixtures allow the determination of weight gain for flax fibres which... |
| Tipo: Text |
Palavras-chave: Natural fibre composites; Seawater ageing; Damage mechanism. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00211/32191/30681.pdf |
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| Le Gall, Maelenn; Davies, Peter; Martin, Nicolas; Baley, Christophe. |
| Density is one of the fundamental properties of fibres which reinforce polymer matrix composites, and is used both to estimate composite weight and to evaluate fibre content for property predictions. For traditional composites, reinforced by glass or carbon fibres, unique density values are well known for a particular fibre grade and provide reliable fibre content estimations and composite property predictions. However, this is not the case for natural fibres. This paper first reviews published density values for flax (Linum usitatissimum L.) fibres and describes the limitations of techniques used to measure fibre density. Significant variations in published densities are found, which can be related to the measurement method. New data quantify the... |
| Tipo: Text |
Palavras-chave: Density; Flax; Archimedes; Pycnometer; Volume fraction; Tensile modulus. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00427/53875/55082.pdf |
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| 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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| 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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| 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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| Registros recuperados: 131 | |
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