References of "Lecomte-Beckers, Jacqueline"
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See detailFinit element modelling of an asynchronous motor with one broken rotor bar, comparison with the data recorded on a prototype and material aspects
Guérard, Suzanne ULg; Gyselinck, Johan; Lecomte-Beckers, Jacqueline ULg

in Bulletin Scientifique de l'AIM (Association des Ingénieurs Electriciens sortis de l'Institut Electrotechnique Montefiore) (2005), 1

This work studies the problem of broken rotor bars in cage induction motors. To this aim, an induction machine from WEG Motors was modelled by means of the finite element method. The motor modelled is a ... [more ▼]

This work studies the problem of broken rotor bars in cage induction motors. To this aim, an induction machine from WEG Motors was modelled by means of the finite element method. The motor modelled is a 18.5 kW four-pole induction motor with a straight rotor cage. The field distribution and stator phase currents were computed for a motor without broken rotor bars and for a motor with one broken rotor bar. The computed stator phase currents were compared to the ones recorded on motors respectively no broken rotor bar and with one broken rotor bar. The FE model and an equivalent scheme of the motor permitted to show that the resistance of the rotor cage was higher than expected, considering only the temperature effect on the conductivity of the rotor bars. A metallurgic analysis of the aluminium alloy of two rotor bars revealed the presence of a very high density of silicon and silicon oxide inclusions, as well as the presence of shrinkages and cracks, which have a negative impact on both conductivity and mechanical strength. A corrected value of the rotor bar conductivity was used in the finite element model and led to a good agreement with the experimental results. The field perturbation associated with a broken rotor bar produces a concentration of flux near the bar ahead of the broken one, considering the counterclockwise direction of rotation of the rotor. This flux concentration results in higher current values and hence in higher stresses in the bar ahead of the broken one. [less ▲]

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See detailDetermination of the optimal forging conditions of a Cr-Mo-V high alloy steel through a microstructural, thermophysical and mechanical study
Bouffioux, Chantal ULg; Carton, Marc ULg; Lecomte-Beckers, Jacqueline ULg et al

in Banabic, D. (Ed.) Proceedings of the 8th ESAFORM Conference on Material Forming (Vol. 1) (2005)

The forging process of cylinders requires the knowledge of material recrystallisation conditions to prevent crack appearance. Due to the continuous recrystallisation during forging, very large ... [more ▼]

The forging process of cylinders requires the knowledge of material recrystallisation conditions to prevent crack appearance. Due to the continuous recrystallisation during forging, very large deformations can be applied as the generated dislocations do not yield to hardening but to recrystallisation phenomenon. This paper summarizes the data identification of a FEM recrystallisation model and defines the optimal forging process for one roll. [less ▲]

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See detailStudy of liquid fraction evolution of semi-solid steels for thixoforming
Lecomte-Beckers, Jacqueline ULg; Rassili, Ahmed ULg; Carton, Marc ULg et al

in Proceedings of the 8th ESAFORM Conference on Material Forming (2005)

Major challenge for semi-solid processing includes broadening the range of alloys that can be successfully thixoformed and developing alloys specifically for thixoforming. One important parameter is ... [more ▼]

Major challenge for semi-solid processing includes broadening the range of alloys that can be successfully thixoformed and developing alloys specifically for thixoforming. One important parameter is appropriate solidus-liquidus interval. The wider the solidification interval, the wider the processing window. This study is related to the experimental determination of this critical parameter on eight different steel compositions. This parameter was obtained using Differential Scanning Calorimetry. This technique allows to obtain the solid fraction versus temperature. [less ▲]

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See detailUse of Microscopy for identification of complex MC, M2C, M6C, M7C3 and M23C6 carbides in high speed-steels
Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg

in GIT - Imaging and Microscopy (2005), 2

High-speed steels (HSSJ rofis are useci in front finishing stands of hot strip mils. Good wear resistance and hardness at high temperature are defining features of HSS. Many types of carbides are present ... [more ▼]

High-speed steels (HSSJ rofis are useci in front finishing stands of hot strip mils. Good wear resistance and hardness at high temperature are defining features of HSS. Many types of carbides are present in these alloys, each having different effect upon the final properties of HSS. As a resuit, nature, morphology and amount of these carbides are factors of important concern. Identification and characterisation of HSS carbides are realised with optical microscopy comhined with electron microscopy. [less ▲]

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See detailStudy of the liquid fraction and thermophysical properties of semi-solid steels and application to the simulation of inductive heating for thixoforming
Lecomte-Beckers, Jacqueline ULg; Rassili, Ahmed ULg; Carton, Marc ULg et al

in Bananic, Dorel (Ed.) Advanced Methods in Material Forming (2005)

The thixoforming of steels is so complex that it requires more investigations regarding both the materials and the technical tools dedicated to the elaboration of the process. In this paper we will show ... [more ▼]

The thixoforming of steels is so complex that it requires more investigations regarding both the materials and the technical tools dedicated to the elaboration of the process. In this paper we will show the experimental determination of appropriate solidus-liquidus interval on eight different steel compositions. This critical parameter was obtained using Differential Scanning Calorimetry. The paper also presents the results of thermophysical property determination. These parameters are important for the inductive heating phase of a semi-solid forming (SSF) process. Thanks to the simulations of the inductive heating process, the other main results consist on the developments of the heating techniques that are suitable for the achieving of the sine qua none condition to the semi-solid process, which is the uniform temperature distribution in the reheated billet. [less ▲]

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See detailTitanium alloys
Lecomte-Beckers, Jacqueline ULg

Scientific conference (2004, June)

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See detailMesoscopic model of intergranular cracks in low carbon steel during cooling of continuous casting
Castagne, S.; Pascon, Frédéric ULg; Lecomte-Beckers, Jacqueline ULg et al

in Lamberigts, M. (Ed.) Proceedings of the 2nd international conference of thermomechanical processing of steels (TMP 2004) (2004)

This paper addresses the problem of transverse cracking during the continuous casting of low carbon steel. The damage mechanisms occurring at high temperature during this process are identified and a ... [more ▼]

This paper addresses the problem of transverse cracking during the continuous casting of low carbon steel. The damage mechanisms occurring at high temperature during this process are identified and a numerical approach for the modelling of these phenomena at the grain scale is proposed. Experiments allowing the identification of the model’s parameters are described. Finally, the first results obtained with the model are presented. [less ▲]

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See detailMelting and crystallisation behaviour of multi-component Fe-C-Cr-X alloys : microstructural aspects
Tchuindjang, Jérôme Tchoufack ULg; Lecomte-Beckers, Jacqueline ULg

in Proceedings of the 13th European Microscopy Congress (2004)

Studied materials are of the Fe-C-Cr-X multi-component system where X represents a group of strong carbides formers as Mo, V, or Nb. These alloys are used for wear components. Differential Thermal ... [more ▼]

Studied materials are of the Fe-C-Cr-X multi-component system where X represents a group of strong carbides formers as Mo, V, or Nb. These alloys are used for wear components. Differential Thermal Analysis (DTA) was used to determine the melting and solidification behaviour of these materials. Raw material has a thermomecanical history that involved casting, heat treating and hot forming, which could be investigated by the melting sequence of the DTA trial. [less ▲]

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See detailStructural investigations of HSS rolls for hot strip mill
Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg; Ernst, R. et al

in Proceedings of the 41st Rolling Seminar Processes, Rolled and Coated Product (2004)

High Speed Steel (HSS) cast rolls are used in front finishing stands of hot strip mills (HSM). Good wear resistance and hardness at high temperatures, are defining features of HSS. Previous experience has ... [more ▼]

High Speed Steel (HSS) cast rolls are used in front finishing stands of hot strip mills (HSM). Good wear resistance and hardness at high temperatures, are defining features of HSS. Previous experience has shown that HSS rolls containing mainly hard MC carbides have a high friction coefficient, which is detrimental for the rolling power consumption and for the strip surface quality. On the other hand, HSS rolls containing eutectic rod shaped carbides are brittle and more susceptible to spalling. To overcome these problems, a suitable grade, called HSS7, that gives the best compromise between a low friction coefficient and a high crack propagation and wear resistance was developed. That alloy contains well-dispersed hard VC carbides improving wear, and non-interconnected eutectic carbides of the M2C and M7C3 type, hindering crack propagation. All the metallurgical factors affecting the performance and damage of under rolling condition in front finishing stands are reviewed: wear resistance, friction coefficient, resistance to rolling incident, and oxide film formation. The effect of nature, morphology and amount was for each of the carbides studied and connected to the factor affecting the behaviour of the new grade developed. Different techniques are used such as: differential thermal analysis, optical and electron scanning microscopy and image analysis. A correlation with mechanical properties was also performed. [less ▲]

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See detailStudy of the cooling process of an extruded aluminium profile
Bouffioux, Chantal ULg; Carton, Marc ULg; Lecomte-Beckers, Jacqueline ULg et al

in Gosh, Somnath; Castro, Jose M.; Lee, June K. (Eds.) Proceedings of Materials Processing and Design: Modeling, Simulation and Applications (NUMIFORM 2004) (2004)

The prediction of the final axial stresses and the residual strains of complex extruded aluminium profiles requires a good knowledge of the material behavior and of the industrial process. This paper is ... [more ▼]

The prediction of the final axial stresses and the residual strains of complex extruded aluminium profiles requires a good knowledge of the material behavior and of the industrial process. This paper is focused on the methods required to provide the whole set of data: material ones and process ones. Scanning differential calorimetry, dilatometry and diffusivity tests identify thermophysic material properties and hot tensile tests identify parameters of the elastovisco- plastic Norton-Hoff law. The description of the industrial process and its simulations are described. Then a sensitivity analyzis provides the cooling key parameters causing the undesired final curvature during the industrial process. [less ▲]

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See detailLingopti project: semi-continuous casting process of copper-nickel alloys
Pecquet, Etienne ULg; Volles, Ralf; Lecomte-Beckers, Jacqueline ULg et al

in Proceedings of the 21st International Congress of Theoritical and Applied Mechanics (2004)

The following text deals with casting of copper-nickel alloys. They are high added values materials. The research contains two main parts. Laboratory tests (completed with bibliography) that provide ... [more ▼]

The following text deals with casting of copper-nickel alloys. They are high added values materials. The research contains two main parts. Laboratory tests (completed with bibliography) that provide thermal and mechanical properties of the ingot and the mould but also heat transfer coefficients between the ingot and its environment (mould, air and water). These parameters are required in the second part : development and validation of numerical modelization by the finite element method to optimise the industrial process. [less ▲]

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See detailCharacterisation of thermophysical properties of semi-solid steels for thixoforming
Lecomte-Beckers, Jacqueline ULg; Rassili, Ahmed ULg; Carton, Marc ULg et al

in Proceedings of the 8th International Conference on Semi-Solid Processing of Alloys and Composites (S2P) (2004)

Major challenge for semi-solid processing includes broadening the range of alloys that can be successfully thixoformed and developing alloys specifically for thixoforming. One important parameter is ... [more ▼]

Major challenge for semi-solid processing includes broadening the range of alloys that can be successfully thixoformed and developing alloys specifically for thixoforming. One important parameter is appropriate solidus-liquidus interval. The wider the solidification interval, the wider the processing window. This study is related to the experimental determination of this critical parameter on eight different steel compositions. This parameter was obtained using Differential Scanning Calorimetry. This technique allows to obtain the solid fraction versus temperature. The paper also presents the results of thermophysical properties determination such as thermal diffusivity, heat capacity and thermal conductivity. These properties were measured from room temperature to semi-solid state in one particular steel. The thermal diffusivity was measured using the Laser Flash method and the heat capacity using a DSC calorimeter. The thermal conductivity was obtained by calculation knowing the thermal dilatation measured with a dilatometer. All these measurements were performed for temperatures up to the liquidus. These parameters are difficult to measure but they are important to determine for the conductive heating phase of a semi-solid forming (SSM) process. [less ▲]

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See detailPreparation of BaZrO3 powders by a spray-drying process
Robertz, B.; Boschini, Frédéric ULg; Rulmont, André ULg et al

in Journal of Materials Research (2003), 18(6), 1325-1332

The potential use of barium zirconate for the manufacture of corrosion-resistant substrates emphasizes the need for a simple, inexpensive, and easily scalable process to produce high-quality powders with ... [more ▼]

The potential use of barium zirconate for the manufacture of corrosion-resistant substrates emphasizes the need for a simple, inexpensive, and easily scalable process to produce high-quality powders with well-controlled composition and properties. However, the classical solid-state preparation of barium zirconate leads to an inhomogeneous powder unsuitable for applications in highly corrosive environment. For this paper, the possibility to use the spray-drying technique for the preparation of BaZrO3 powders with a controlled size distribution and morphology was investigated. The influence of the nature and concentration of the precursor solution and the influence of the spray-drying step are discussed on the basis of x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and dilatometric measurements. [less ▲]

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