References of "Legrand, Nicolas"
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See detailUltrasonic roll bite measurements in cold rolling - roll stress and deformation
Carretta, Yves; Hunter, Andrew; Boman, Romain ULiege et al

in Journal of Materials Processing Technology (2017), 249

In cold rolling of thin metal strip, contact conditions between the work rolls and the strip are of great importance: roll deformations and their effect on strip thickness variation may lead to strip ... [more ▼]

In cold rolling of thin metal strip, contact conditions between the work rolls and the strip are of great importance: roll deformations and their effect on strip thickness variation may lead to strip flatness defects and thickness inhomogeneity. To control the process, several online measurements are usually carried out such as the rolling load, forward slip and strip tensions at each stand. Shape defects of the strip are usually evaluated after the last stand of a rolling mill thanks to a flatness measuring roll. However, none of these measurements is made within the roll bite itself due to the harsh conditions taking place in that area. This paper presents a sensor capable of monitoring roll deformations as well as roll radial stresses in situ and in real time. The sensor emits ultrasonic pulses that reflect from the roll surface. The time-of-flight (ToF) of the pulses is recorded during the testing. The sensor system was incorporated into a work roll and tested on a pilot rolling mill. Measurements were taken as steel strips were rolled under different strip elongation. Roll deformation and radial stresses obtained from the experimental data are in good agreement with numerical results computed with a cold rolling model developed in non-linear Finite Element software. [less ▲]

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See detailNumerical modelling of micro-plasto-hydrodynamic lubrication in plane strip drawing
Carretta, Yves ULiege; Bech, Jakob; Legrand, Nicolas et al

in Tribology International (2017), 110

This paper presents a new finite element model capable of predicting the onset of micro-plasto-hydrodynamic (MPH) lubrication and the amount of lubricant escaping from surface pockets in metal forming ... [more ▼]

This paper presents a new finite element model capable of predicting the onset of micro-plasto-hydrodynamic (MPH) lubrication and the amount of lubricant escaping from surface pockets in metal forming. The present approach is divided in two steps. First, a simulation at the macroscopic level is conducted. Then, a second simulation highlighting microscopic liquid lubrication mechanisms is achieved using boundary conditions provided by the first model. These fluid-structure interaction computations are made possible through the use of the Arbitrary Lagrangian Eulerian (ALE) formalism. The developed methodology is validated by comparison to experimental measurements conducted in plane strip drawing. The effect of physical parameters like the drawing speed, the die angle and the strip thickness reduction is investigated. The numerical results show good agreement with experiments. [less ▲]

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See detailUltrasonic roll bite measurements in cold rolling: Contact length and strip thickness
Carretta, Yves; Hunter, Andrew; Boman, Romain ULiege et al

in Proceedings of the Institution of Mechanical Engineers - Part J - Journal of Engineering Tribology (2017)

In cold rolling of thin metal strip, contact conditions between the work rolls and the strip are of great importance: roll deformations and their effect on strip thickness variation may lead to strip ... [more ▼]

In cold rolling of thin metal strip, contact conditions between the work rolls and the strip are of great importance: roll deformations and their effect on strip thickness variation may lead to strip flatness defects and thickness inhomogeneity. To control the process, online process measurements are usually carried out; such as the rolling load, forward slip and strip tensions at each stand. Shape defects of the strip are usually evaluated after the last stand of a rolling mill thanks to a flatness measuring roll. However, none of these measurements is made within the roll bite itself due to the harsh conditions taking place in that area. This paper presents a sensor capable of monitoring strip thickness variations as well as roll bite length in situ and in real time. The sensor emits ultrasonic pulses that reflect from the interface between the roll and the strip. Both the time-of-flight of the pulses and the reflection coefficient (the ratio of the amplitude of the reflected signal to that of the incident signal) are recorded. The sensor system was incorporated into a work roll and tested on a pilot rolling mill. Measurements were taken as steel strips were rolled under several lubrication conditions. Strip thickness variation and roll-bite length obtained from the experimental data agree well with numerical results computed with a cold rolling model in the mixed lubrication regime. [less ▲]

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See detailNumerical modelling of microscopic lubricant flow in sheet metal forming. Application to plane strip drawing
Carretta, Yves; Bech, Jacob; Legrand, Nicolas et al

in International Journal for Numerical Methods in Engineering (2017)

This paper presents a numerical investigation of microscopic lubricant flows from the cavities to the plateaus of the surface roughness of metal sheets during forming processes. This phenomenon, called ... [more ▼]

This paper presents a numerical investigation of microscopic lubricant flows from the cavities to the plateaus of the surface roughness of metal sheets during forming processes. This phenomenon, called micro-plastohydrodynamic lubrication, was observed experimentally in various situations such as compression sliding tests, strip drawing and cold rolling. It leads to local friction drop and wear reduction. It is therefore critical to achieve a good understanding of this phenomenon. As to move towards that goal, a multiscale fluid–structure interaction model is developed to model lubricant flows at the microscopic scale. These simulations are made possible through the use of the Arbitrary Lagrangian Eulerian (ALE) formalism. In this paper, this methodology is used to study plane strip drawing. The numerical model is able to predict the onset of lubricant escape and the amount of lubricant flowing on the plateaus. Numerical results exhibit good agreement with experimental measurements. [less ▲]

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See detailComplementary approaches for the numerical simulation of the Micro- Plasto-Hydrodynamic Lubrication regime
Hubert, Cédric; Dubois, André; Dubar, Laurent et al

in Key Engineering Materials [=KEM] (2015), 651-653

This paper presents recent investigations in the field of lubricant escapes from asperities. This phenomenon, named Micro Plasto Hydrodynamic Lubrication (MPHL), induces friction variation during metal ... [more ▼]

This paper presents recent investigations in the field of lubricant escapes from asperities. This phenomenon, named Micro Plasto Hydrodynamic Lubrication (MPHL), induces friction variation during metal forming processes. A better understanding of MPH lubrication would lead to a better management of friction, which is a central element in most sheet metal forming processes. To fulfil that goal, experiments were conducted in plane strip drawing using a transparent upper tool in order to observe lubricant flow around macroscopic pyramidal cavities. These experiments were then numerically reproduced with two complementary Finite Element models. The numerical results are discussed in this paper and show good agreement with experimental measurements. [less ▲]

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See detailMicro-plasto-hydrodynamic lubrication: a fundamental mechanism in cold rolling
Laugier, Maxime; Boman, Romain ULiege; Legrand, Nicolas et al

in Advanced Materials Research (2014), 966-967

Micro Plasto-Hydrodynamic (MPH) lubrication is a general mechanism in metal forming that consists in a re-lubrication of tool-piece solid contacts by an outflow of lubricant from pressurized “pockets” ... [more ▼]

Micro Plasto-Hydrodynamic (MPH) lubrication is a general mechanism in metal forming that consists in a re-lubrication of tool-piece solid contacts by an outflow of lubricant from pressurized “pockets” promoted by the plastic deformation. MPH lubrication is one of the main sources of friction variation (e.g. uncontrolled friction) in metal forming processes like strip drawing or cold rolling. This paper presents experimental results giving evidence of the MPH lubrication mechanism in cold rolling and a new lubrication model that predicts for strip drawing conditions MPH lubrication initiation and lubricant extension along the solid contacts initially in boundary condition. This MPH model could be implemented in a cold rolling model soon to help in high strength steels developments on cold rolling mills. [less ▲]

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See detailNumerical simulations of asperity crushing using boundary conditions encountered in cold-rolling
Carretta, Yves ULiege; Boman, Romain ULiege; Legrand, Nicolas et al

in Key Engineering Materials [=KEM] (2013), 554-557

Asperity flattening has a huge influence on friction and wear in metal forming processes. Nevertheless, phenomena that occur at the microscopic scale are still not well understood. Since no experiment can ... [more ▼]

Asperity flattening has a huge influence on friction and wear in metal forming processes. Nevertheless, phenomena that occur at the microscopic scale are still not well understood. Since no experiment can be easily performed in real forming conditions, numerical models are essential to achieve a better knowledge of what happens in these contact regions. In this paper, two finite elements models are presented. The first one represents the flattening of a serrated asperity field in plane-strain conditions. The results are compared to the experiments published by Sutcliffe [1]. The second one is a tri-dimensional asperity model flattened by a rigid plane. The boundary conditions applied to this model correspond to the ones encountered in a real cold-rolling case. The results are compared to the relative contact area computed by a strip rolling model using the analytical laws proposed by Wilson & Sheu [2] and Marsault [3]. [less ▲]

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See detailThree-dimensional Modelling of Asperity Crushing
Carretta, Yves ULiege; Boman, Romain ULiege; Legrand, Nicolas et al

Conference (2012, October)

Asperity flattening has a huge influence on friction and wear in metal forming processes. Nevertheless, phenomena that occur at the microscopic scale are still not well understood. Since no experiment can ... [more ▼]

Asperity flattening has a huge influence on friction and wear in metal forming processes. Nevertheless, phenomena that occur at the microscopic scale are still not well understood. Since no experiment can be easily performed in real forming conditions, numerical models are essential to achieve a better knowledge of what happens in these contact regions. In this paper, a threedimensional model of a rough strip flattened by a rigid rough tool is presented. The boundary conditions applied to this model correspond to the ones encountered in a real cold-rolling case. The results are compared to experimental measurements from the pilot mill of ArcelorMittal Maizières R&D. [less ▲]

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See detailArbitrary Lagrangian Eulerian Modelling of Tension Levelling
Boman, Romain ULiege; Parrico, Anthony; Legrand, Nicolas et al

in Matériaux et Techniques (2012, October), 100(Hors série 2012), 40-42

This paper presents a two-dimensional model of tension levelling using the Arbitrary Lagrangian Eulerian (ALE) approach. During the simulation, the ALE mesh remains globally fixed along the rolling ... [more ▼]

This paper presents a two-dimensional model of tension levelling using the Arbitrary Lagrangian Eulerian (ALE) approach. During the simulation, the ALE mesh remains globally fixed along the rolling direction. Therefore, the required number of finite elements is much smaller than in the Lagrangian case and smaller CPU times are obtained for the same accuracy on the results. The ALE model is first validated against a classical equivalent Lagrangian model. Then, both sets of numerical results are compared to experimental measurements from the pilot mill of ArcelorMittal Maizières R&D. [less ▲]

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See detailMixed Lubrication Regime in Cold Strip Rolling
Carretta, Yves ULiege; Boman, Romain ULiege; Legrand, Nicolas et al

in 2nd Annual ArcelorMittal CFD and Thermomechanics Days 2012 (2012, January)

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See detailMETALUB – A Slab Method Software for the Numerical Simulation of Mixed Lubrication Regime in Cold Strip Rolling
Carretta, Yves ULiege; Boman, Romain ULiege; Stephany, Antoine et al

in Proceedings of the Institution of Mechanical Engineers - Part J - Journal of Engineering Tribology (2011), 225(9), 894-904

A cold rolling model taking into account mixed lubrication regime has been developed and included into a simulation software named MetaLub. The main objective is to enhance the performances of rolling ... [more ▼]

A cold rolling model taking into account mixed lubrication regime has been developed and included into a simulation software named MetaLub. The main objective is to enhance the performances of rolling mills from a lubrication point of view. It means that lubricant rheology but also roll diameters and roughness, etc., can be optimised to improve stability and efficiency of the rolling tool. The main features of MetaLub, are briefly presented in this paper. Then, two studies of the influence of rolling speed and negative forward slip are discussed. The obtained numerical results are presented and compared to some experimental data from literature and from ArcelorMittal facilities in order to validate the model and to show its capacity to understand and help to improve industrial rolling conditions. [less ▲]

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See detailThermomechanical simulation of roll forming process based on the coupling of two independent solvers
Carretta, Yves ULiege; Boman, Romain ULiege; Stephany, Antoine et al

in Proceedings of the IV International Conference on Computational Methods for Coupled Problems in Science and Engineering COUPLED PROBLEMS 2011 (2011, June)

This paper deals with an industrial application of a coupling procedure involving two different computer programs : MetaLub and ThermRoll. The first one models the mechanical phenomena occurring in the ... [more ▼]

This paper deals with an industrial application of a coupling procedure involving two different computer programs : MetaLub and ThermRoll. The first one models the mechanical phenomena occurring in the roll-bite during cold rolling such as elasto-plastic strip strains, elastic-roll deformations, asperity flattening and lubricant flow. The second one uses the previous results to compute the steady-state temperature field of the work-roll and the strip. These two codes are briefly described and a model of an industrial stand demonstrates the importance of the thermomechanical coupling in order to get a better understanding of the process. [less ▲]

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See detailNumerical Simulations of Asperity Crushing - Application to Cold Rolling
Carretta, Yves ULiege; Legrand, Nicolas; Laugier, Maxime et al

in Proceedings of ESAFORM : Belfast, 27-29th april 2011 (2011)

Asperity flattening has a huge influence on friction and wear in metal forming processes. Nevertheless, phenomena that occur at the microscopic scale are still not well understood. Since no experiments ... [more ▼]

Asperity flattening has a huge influence on friction and wear in metal forming processes. Nevertheless, phenomena that occur at the microscopic scale are still not well understood. Since no experiments can be easily performed in real forming conditions, numerical models are essential to achieve a better knowledge of what happens in these contact regions. In this paper, two finite elements models are presented. The first one represents the flattening of a serrated asperity field in plane strain conditions. The results are compared to the experiments conducted by Sutcliffe [1]. The second one is a tri-dimensional asperity model flattened by a rigid plane. The boundary conditions applied to this model correspond to the ones encountered in a real cold rolling case. The results are compared to the relative contact area computed by a strip rolling model using the analytical laws proposed by Wilson & Sheu [2] and Marsault [3]. [less ▲]

Detailed reference viewed: 40 (10 ULiège)
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See detailMetalub – A Slab Method software for the numerical simulation of mixed lubrication regime. Application to cold rolling
Carretta, Yves ULiege; Stephany, Antoine; Legrand, Nicolas et al

in ICTMP 2010 - International Conference on Tribology in Manufacturing processes (2010)

Detailed reference viewed: 82 (20 ULiège)