Article (Scientific journals)
Numerical simulations of asperity crushing using boundary conditions encountered in cold-rolling
Carretta, Yves; Boman, Romain; Legrand, Nicolas et al.
2013In Key Engineering Materials, 554-557, p. 850-857
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].
Peer Reviewed verified by ORBi
Paper published in a book (Scientific congresses and symposiums)
Mixed Lubrication Regime in Cold Strip Rolling
Carretta, Yves; Boman, Romain; Legrand, Nicolas et al.
2012In 2nd Annual ArcelorMittal CFD and Thermomechanics Days 2012
Unpublished conference/Abstract (Scientific congresses and symposiums)
Three-dimensional Modelling of Asperity Crushing
Carretta, Yves; Boman, Romain; Legrand, Nicolas et al.
2012Journées Annuelles de la SF2M 2012
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.
Article (Scientific journals)
Complementary approaches for the numerical simulation of the Micro- Plasto-Hydrodynamic Lubrication regime
Hubert, Cédric; Dubois, André; Dubar, Laurent et al.
2015In Key Engineering Materials, 651-653, p. 492-497
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.
Peer Reviewed verified by ORBi
Doctoral thesis (Dissertations and theses)
Modélisation des conditions d’apparition du micro-hydrodynamisme via la méthode des éléments finis dans la perspective d’intégrer ce phénomène dans un modèle numérique de laminage à froid.
Carretta, Yves
2014
This dissertation presents a finite element numerical model able to predict the occurrence of Micro-Plasto-Hydrodynamic (MPH) lubrication. This phenomenon, which was first introduced by Mizuno and Okamoto, appears in the mixed lubrication regime. It consists in lubricant flows at the microscopic scale leading to a lubrication of the tool-piece solid contacts and therefore to a local friction drop. For instance, Laugier et al. have observed a friction decrease while rolling High Strength Steels for different strip thickness reductions. The only physical explanation to this trend is the MPH lubrication. Despite the huge influence of MPH lubrication on friction in metal forming processes, only a few numerical models can be found in the literature. Moreover, these models rely on several restrictive assumptions which prevent them from delivering predictive results. This work consists in the development of the first finite element model capable of predicting the appearance of the MPH lubrication. This model is used to numerically reproduce the experiments of Bech who studied this phenomenon, in plane strip drawing, by observing the behaviour of macroscopic pyramidal lubricant cavities through a transparent die. In the proposed approach, plane strip drawing is modelled in 2D with Metafor, an in-house nonlinear FE code. This model allows us to compare the lubricant pressure to the solid-solid contact pressure profile between the upper die and the strip material. Once the lubricant pressure exceeds the solid-to-solid contact pressure, the condition allowing a lubricant flow from the pocket to the neighbouring plateaus is fulfilled. The presented FE model is able to predict backward and forward escapes of the lubricant from the pocket. As in the experiments of Bech, several parametric studies have been carried out. The numerical results show that the model reproduces the trends observed experimentally.
Article (Scientific journals)
Numerical modelling of micro-plasto-hydrodynamic lubrication in plane strip drawing
Carretta, Yves; Bech, Jakob; Legrand, Nicolas et al.
2017In Tribology International, 110, p. 378-391
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.
Peer Reviewed verified by ORBi
Paper published in a book (Scientific congresses and symposiums)
Thermomechanical simulation of roll forming process based on the coupling of two independent solvers
Carretta, Yves; Boman, Romain; Stephany, Antoine et al.
2011In Proceedings of the IV International Conference on Computational Methods for Coupled Problems in Science and Engineering COUPLED PROBLEMS 2011
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.
Peer reviewed
Article (Scientific journals)
METALUB – A Slab Method Software for the Numerical Simulation of Mixed Lubrication Regime in Cold Strip Rolling
Carretta, Yves; Boman, Romain; Stephany, Antoine et al.
2011In Proceedings of the Institution of Mechanical Engineers. Part J, Journal of Engineering Tribology, 225 (9), p. 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 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.
Peer Reviewed verified by ORBi
Paper published in a book (Scientific congresses and symposiums)
Metalub – A Slab Method software for the numerical simulation of mixed lubrication regime. Application to cold rolling
Carretta, Yves; Stephany, Antoine; Legrand, Nicolas et al.
2010In ICTMP 2010 - International Conference on Tribology in Manufacturing processes
Peer reviewed
Article (Scientific journals)
Micro-plasto-hydrodynamic lubrication: a fundamental mechanism in cold rolling
Laugier, Maxime; Boman, Romain; Legrand, Nicolas et al.
2014In Advanced Materials Research, 966-967, p. 228-241
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.
Peer reviewed
Paper published in a book (Scientific congresses and symposiums)
Numerical Simulations of Asperity Crushing - Application to Cold Rolling
Carretta, Yves; Legrand, Nicolas; Laugier, Maxime et al.
2011In Proceedings of ESAFORM : Belfast, 27-29th april 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 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].
Peer reviewed