References of "Lecomte-Beckers, Jacqueline"
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See detailA pendulum test as a tool to evaluate viscous friction parameters in the equine fetlock joint
Noble, Prisca ULg; Lumay, Geoffroy ULg; Coninx, Marc ULg et al

Poster (2010, April)

This study describes an equine fetlock joint pendulum test, and investigates the influence of post mortem time and intra-articular lipid solvent on the viscous frictional response. Fresh equine digits ... [more ▼]

This study describes an equine fetlock joint pendulum test, and investigates the influence of post mortem time and intra-articular lipid solvent on the viscous frictional response. Fresh equine digits (control group 1 (n = 6); lipid solvent group 2 (n = 6)) were mounted in a pendulum tribometer. Assuming that pendular joint damping could be modelled by a harmonic oscillator fluid damping (HOFD), damping time (t), viscous damping coefficient (c ) and friction coefficient (µ) were then followed for 5 hours under experimental conditions (400 N; 20 °C). In all experiments, pendular joint damping was found to follow an exponential decay function (R² = 0.99714), which confirms that joint damping is fluid. The evolution of t, c and µ was found to be significantly (P <0.05) different in the two groups. Indeed, t decreased and c and µ increased more rapidly and strongly in the group 2. It was concluded that pendular joint damping can be modelled by an HOFD model. The influence of post mortem time on results suggests that, ideally, joint mechanical properties should only be tested on fresh cadavers at the same post mortem time. Finally, the addition of lipid solvent was found to be responsible for upper viscous friction parameters and for a reduced damping time, which suggests that articular lubricating ability was compromised. This equine pendulum test could be used to test the efficacy of various bio-lubricant treatments. [less ▲]

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See detailAn equine joint friction test model using a cartilage-on-cartilage arrangement.
Noble, Prisca ULg; Collin, Bernard ULg; Lecomte-Beckers, Jacqueline ULg et al

in Veterinary Journal (2010)

This study describes an equine joint friction test using a cartilage-on-cartilage arrangement and investigates the influence of age and load on the frictional response. Osteochondral plugs were extracted ... [more ▼]

This study describes an equine joint friction test using a cartilage-on-cartilage arrangement and investigates the influence of age and load on the frictional response. Osteochondral plugs were extracted from equine shoulder joints (2-5 years, n=12; 10-14 years, n=15), and mounted in a pin-on-disc tribometer. The frictional response was then measured under constant conditions (2N; 20 degrees C; 5 mm/s), and with increasing load (2N, 5N, 10N). In all experiments, the friction coefficient of young cartilage was significantly (P<0.001) smaller than obtained from old cartilage, while the application of a greater load resulted in a significant (P<0.001) decrease in friction coefficient only in old cartilage. It was concluded that cartilage ageing was responsible for an increase in friction coefficient under these experimental conditions. Moreover, where young cartilage lubrication remained stable, cartilage ageing may have been responsible for lubrication regime change. The cartilage-on-cartilage model could be used to better understand lubrication regime disturbances in healthy and diseased equine joints, and to test the efficacy of various bio-lubricant treatments. [less ▲]

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See detailFissuration de dépôts durs à base de Ni et de Co en Laser Cladding
Montrieux, Henri-Michel ULg; Lecomte-Beckers, Jacqueline ULg

Report (2010)

Le rapport concerne l'étude de la fissuration de dépôts durs en Ni-Cr-Fe-B-Si réalisés par Laser Cladding. Il est montré que la fissuration est provoquée par la présence de contraintes mécaniques ... [more ▼]

Le rapport concerne l'étude de la fissuration de dépôts durs en Ni-Cr-Fe-B-Si réalisés par Laser Cladding. Il est montré que la fissuration est provoquée par la présence de contraintes mécaniques résiduelles d'origine thermique et on se trouve face à un phénomène de fissuration à froid. Le travail comporte également la comparaison de 4 nuances de poudre différentes utilisées en Laser Cladding au niveau du coefficient de dilatation thermique et des microstructures. La présence de composés céramiques (borure ou carbure) de nature pro-eutectique a pour effet de diminuer le coefficient de dilatation mais d'augmenter la fragilité. Le rôle du coefficient de dilatation thermique dans la fissuration semble être moins important que la nature de la microstructure en elle-même. Le choix de nuances présentant une structure hypo-eutectique et une haute dureté semble être pertinent en ce qui concerne l'établissement d'un compromis entre la dureté et la résilience de ces matériaux particuliers. [less ▲]

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See detailL'articulation synoviale : un systeme tribologique parfait
Noble, Prisca ULg; Collin, Bernard ULg; Lecomte-Beckers, Jacqueline ULg et al

in Annales de Médecine Vétérinaire (2010), 154(2), 83-93

The synovial joint, by load bearing and by minimal wear and minimal friction conferring, is considered as a perfect tribological system. During these last years, researchs in articular biomechanics have ... [more ▼]

The synovial joint, by load bearing and by minimal wear and minimal friction conferring, is considered as a perfect tribological system. During these last years, researchs in articular biomechanics have been performed to study how the joint friction coefficient, a dimensionless measure which represents the ratio between the frictional force on the normal force, was close to zero. Today, there is still no consensual explanation and the articular prosthesis partially imitates the biological mechanics. This review describes the composition and the general properties of the synovial joint components. Additionally, different theorical models, on the tribology of the articular triplex cartilage-synovial fluid-cartilage, are explained. [less ▲]

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See detailFriction coefficients evaluation for steel thixoforging
Pierret, Jean-Christophe ULg; Rassili, Ahmed ULg; Vaneetveld, Grégory ULg et al

in Proceedings of The 13th Esaform Conference on Material Forming (2010) - semi-solid processing (2010)

Since the first works on thixoforming, lot of studies have been performed all over the world and the behaviour of the globular semi-solid slurry is now quite well understood. This knowledge had lead to an ... [more ▼]

Since the first works on thixoforming, lot of studies have been performed all over the world and the behaviour of the globular semi-solid slurry is now quite well understood. This knowledge had lead to an industrialisation of the technology for low melting point alloys as aluminium or magnesium. For high melting point alloys as steel, this industrialisation is still a wish but seems closer each year. In the aim of this development of the process, it is important to be able to accurately represent the behaviour of the slurry during thixoforming. In this goal, lot of constitutive models has been proposed during the last years. However, until now there isn’t any study about the friction in the case of thixoforming. This knowledge is needed as friction has an important effect on the flow of the slurry during the shaping. The aim of this work is so to propose a quantification of the friction coefficients for the thixoforming technology thanks to experiments on a dedicated tool and comparison with simulations run on the finite elements code Forge2008©. The friction law is a Coulomb limited Tresca one. [less ▲]

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See detailMaterials for advanced power engineering 2010 : Proceedings of the 9th Liège conference
Lecomte-Beckers, Jacqueline ULg; Contrepois, Quentin ULg; Kuhn, F. et al

Book published by Schriften des Forschungszentrum Julich, Reihe energietechnik/Energy Technology Forschungszentrum Julich (2010)

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See detailBenefits of thixoforging hot-crack-sensitive aluminium alloys at high solid fraction
Vaneetveld, Grégory ULg; Rassili, Ahmed ULg; Pierret, Jean-Christophe ULg et al

in International Journal of Material Forming (2010), 2

Detailed reference viewed: 47 (19 ULg)
See detailIdentification of Suitable Steels : Chapter 3
Rassili, Ahmed ULg; Robelet, Marc; Lecomte-Beckers, Jacqueline ULg

in Rassili, Ahmed; Atkinson, Helen (Eds.) Thixoforming steels (2010)

A range of steels is normally industrially available. The question here is to identify those which are most suitable for thixoforming and to adapt the composition to maximise the chances of success. In ... [more ▼]

A range of steels is normally industrially available. The question here is to identify those which are most suitable for thixoforming and to adapt the composition to maximise the chances of success. In this chapter, the influence of alloying elements on the solidus and liquidus temperatures and on the thixoforming window is identified. Some case studies for low and medium carbon steels are given. Thermophysical properties are important for processing and some information is given on the characterisation of these. High carbon chromium steels are another class of steels which are potentially of use. The effect of modifying the Mn and Si content of such steels is described. Thermodynamic prediction is a powerful tool and results from such studies are given. There is then an analysis of the influence of micro-segregation, which results from the original hot rolling, and its interaction with heating speed during the reheating for thixoforming. [less ▲]

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See detailStudy of Carbon Fibre-Reinforced Magnesium Composites (Introduction to interfacial phenomenon)
Montrieux, Henri-Michel ULg; Lecomte-Beckers, Jacqueline ULg

Conference (2009, November 06)

Composite materials are known to combine interesting properties of different materials. This research concerns magnesium alloys reinforced by carbon fibres weaves. Such a material can theoretically ... [more ▼]

Composite materials are known to combine interesting properties of different materials. This research concerns magnesium alloys reinforced by carbon fibres weaves. Such a material can theoretically exhibit a yield strength/density ratio around 500 compared to ~200 for Ti6Al4V and ~125 for Al2024-T6. This composite is thought to be especially promising for aeronautics if interaction between fibres and magnesium can be controlled and optimized. The strategy studied to enhance interaction between matrix and fibres consists in covering a thin layer of carbide former metal (Zr, Ti) by PVD as a primary treatment of carbon weaves. This intermediate product can then be heated up between 300-700°C in an argon atmosphere in order to form stable carbides. The wetability of treated weaves by liquid magnesium is potentially higher because carbides are not fully covalent (partially metallic) and so they can have more interface interaction with liquid metals. Further crystal lattice parameters of particular carbides can be close to the ones of metal crystal lattices and interface energy can consequently be reduced when they form carbide-metal bonds. Furthermore magnesium is known for its high oxygen attraction and is able to reduce a lot metallic oxides. It is a key fact because liquid magnesium easy wets its oxide in certain conditions. [less ▲]

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See detailDépôt Laser de poudre à base Fe-C-Mn-Cr et WC/W2C
Montrieux, Henri-Michel ULg; Lecomte-Beckers, Jacqueline ULg

Report (2009)

Le présent rapport concerne l'analyse de dépôts réalisés par Laser Cladding. Ces dépôts sont composés d'une matrice en acier au carbone contenant 13 wt.% de Mn et 14 wt.% de Cr et de granules sphéroïdales ... [more ▼]

Le présent rapport concerne l'analyse de dépôts réalisés par Laser Cladding. Ces dépôts sont composés d'une matrice en acier au carbone contenant 13 wt.% de Mn et 14 wt.% de Cr et de granules sphéroïdales dures à base de WC/W2C métastable. Le rapport met en évidence le phénomène de décomposition du carbure de tungstène. Le carbure décomposé libère du tungstène dans la matrice métallique et provoque la précipitation localisée d'intermétallique Fe-W qui ont une tendance fragilisante. La matrice métallique d'une composition proche de l'acier Hadfield ne semble pas durcir de manière conséquente lors de chocs. La formation de martensite semble donc écartée dans ces conditions. [less ▲]

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See detailRapid prototyping
Verlee, Bruno; Dormal, Thierry ULg; Clarinval, Anne-Marie et al

Conference (2009, February 25)

In opposition to traditional machining in which part is manufactured by material removal, rapid prototyping techniques allow parts manufacturing by material addition. The part is built layer-by-layer and ... [more ▼]

In opposition to traditional machining in which part is manufactured by material removal, rapid prototyping techniques allow parts manufacturing by material addition. The part is built layer-by-layer and the sum of all layers creates the part. Currently, several techniques exist. They use different kind of materials (metals, ceramics, polymers) and technologies (laser melting, laser polymerising, 3D-printing, cladding, ...). Some of these techniques can deal with nanometric particles. In the case of which a near net shape part is built and must be sintered after shaping, the addition of nano-particles can be useful for sintering by increasing specific surface and reactivity of the batch or by improving the properties of the material. An overview about techniques of rapid prototyping allowing the processing of nanomaterials will be discussed. Tests have been done using Optoform process. This process uses a laser to polymerize a paste made of photo-curable resin loaded with powdered material. Nano-particles can be added and stabilized in the paste. In this presentation, the results obtained with both systems Al2O3 + nano Zr02 and SiC + Nano SiC will be discussed. [less ▲]

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