References of "Boman, Romain"
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See detailPreoperative Brain Image Update with FEM- and XFEM-based Biomechanical Model
Vigneron, Lara; Boman, Romain ULg; Robe, Pierre et al

in 7th World Congress on Computational Mechanics (2006, July)

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See detailSpringback and Twist Prediction of Roll Formed Parts
Bui, Quoc Viet; Boman, Romain ULg; Papeleux, Luc ULg et al

in Santos, Abel D.; Barata da Rocha, A. (Eds.) Proceedings of the IDDRG 2006 International Deep Drawing Research Group, Drawing the things to come, Trends and Advances in Sheet Metal Forming (2006, June)

In the construction market, Roll Forming is the reference forming process. Numerous parts are achieved in such a way: purlins, steeldecks or suspended ceiling parts are examples of it. Roll Forming is ... [more ▼]

In the construction market, Roll Forming is the reference forming process. Numerous parts are achieved in such a way: purlins, steeldecks or suspended ceiling parts are examples of it. Roll Forming is also more and more used in the automotive industry, as it constitutes a good alternative to forming for High Strength Steels. Among the major requirements to obtain a defect-free product are outlined: the accurate geometry of the part, the taking into account of the springback as well as the prediction of twist. Furthermore, the roll forming operation could be only the first forming operation: the part could be curved or locally deep drawn afterwards. FE codes could allow fulfilling these requirements. However, they need significant advances in terms of material model description and numerical development. This paper presents the work done in order to predict the geometry and the behaviour of a roll formed part: First the material is characterized in complex strain paths in order to identify elaborated microstructural model like Teodosiu’s one. This model is able to take into account Bauschinger effect, orthogonal strain paths, isotropic/kinematic hardening. The METAFOR code is then used to have a better understanding of the mechanics of the deformation of the strip during the forming process. Several experimental campaigns were performed on the I-R&D ARCELOR roll forming machine to define a strong database in order to validate the numerical results. The geometry of machine as well as the shape of the channels inside and outside the RF machine were measured. Some experiments were even carried out in order to generate defects like twist in the roll formed profile. [less ▲]

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See detailA 3D Arbitrary Lagrangian Eulerian Formulation for the Numerical Simulation of Forming Processes. Application to cold roll forming and metal cutting
Boman, Romain ULg; Papeleux, Luc ULg; BUI, Q. V. et al

in Mota Soares, C. A. (Ed.) Proceedings of ECCM 2006, III European Conference on Computational Mechanics, Solids, Structures and Coupled Problems in Engineering (2006, June)

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See detailAn ALE Model for Numerical Simulation of Cold Roll Forming Process
Boman, Romain ULg; Papeleux, Luc ULg; Viet, B. Q. et al

in AIP Conference Proceedings (2005, August 05), 778

In this paper, the Arbitrary Lagrangian Eulerian formalism is used to compute the steady state of a 3D U-shaped cold roll forming process. Compared to the Lagrangian case, this method allows the use of a ... [more ▼]

In this paper, the Arbitrary Lagrangian Eulerian formalism is used to compute the steady state of a 3D U-shaped cold roll forming process. Compared to the Lagrangian case, this method allows the use of a refined mesh near the tools, leading to an accurate representation of the bending of the sheet with a limited computational time. The main problem of this kind of simulation is the rezoning of the nodes on the free surfaces of the sheet. A modified iterative isoparametric smoother is used to manage this geometrically complex and CPU expensive task. [less ▲]

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See detailALE simulations using Metafor
Boman, Romain ULg

Scientific conference (2005, May)

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See detailNumerical Simulation of Cold Roll Forming Process
Bui, Quoc Viet; Papeleux, Luc ULg; Boman, Romain ULg et al

in Banabic, Dorel (Ed.) Proceedings of the 8th ESAFORM Conference on Material Forming (2005, April)

Cold roll-forming process of a U profile is modelled and simulated. The simulation is based on a 3D finite element analysis with the help of the home made Metafor code. The prediction on dimensions and ... [more ▼]

Cold roll-forming process of a U profile is modelled and simulated. The simulation is based on a 3D finite element analysis with the help of the home made Metafor code. The prediction on dimensions and deformed shape of the cold roll-formed sheet is in good agreement with the experimental results. Parametric study on roll forming parameters, such as the yield limit and the hardening property of materials, and the distance between stations is performed. [less ▲]

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See detailNumerical simulation of tribological devices used as a set of benchmarks for comparing contact algorithms
Chabrand, Patrick; Dubois, Frédéric; Graillet, Denis et al

in Finite Elements in Analysis & Design (2005), 41(6), 637-665

The aim of the present study was to carry out a numerical comparison of different frictional contact algorithms. Therefore three different contact algorithms (Lemke, penalty and Augmented Lagrangian) have ... [more ▼]

The aim of the present study was to carry out a numerical comparison of different frictional contact algorithms. Therefore three different contact algorithms (Lemke, penalty and Augmented Lagrangian) have been implemented into two. finite element codes. The correct implementation and behavior of these contact algorithms has been investigated by modeling four different tribological devices. It is shown that all these different methodologies lead to extremely similar results. Besides these four applications have been carefully described and detailed in such a way that the presented tests can be reproduced. The authors wish that they could serve as a benchmark set in order to allow comparison with other finite element software including frictional contact capabilities. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailArchitecture de Metafor - code EF orienté objet
Boman, Romain ULg

Scientific conference (2005, February)

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See detailFinite Element Simulation of Lubricated Contact in Rolling using the Arbitrary Lagrangian-Eulerian Formulation
Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Computer Methods in Applied Mechanics and Engineering (2004), 193(39-41), 4323-4353

In this paper, the lubrication problem in numerical simulation of forming processes is considered. Two efficient convection algorithms are presented in order to update the value stored at the Gauss points ... [more ▼]

In this paper, the lubrication problem in numerical simulation of forming processes is considered. Two efficient convection algorithms are presented in order to update the value stored at the Gauss points during the Eulerian step of an arbitrary Lagrangian Eulerian computation in solid mechanics. They are based on the finite volume method and on the streamline upwind Petrov Galerkin method. After enumerating the difficulties encountered when trying to solve the lubrication problem with the finite element method, a generalization of the formulation introduced by Liu [Simulation of Ring Rolling Process by Arbitrary Lagrangian Eulerian Finite Element Method, vol. 20, p. 225; ASME Winter Meeting, Dallas, Tx, 1990, Int. J. Numer. Methods Engrg. 36 (1993) 855; Numerical Methods in Industrial Forming Processes, Valbonne, France, 1992, p. 731] for the thin film hydrodynamic lubrication regime is presented. This method is then applied to a strip rolling simulation, using the arbitrary Lagrangian Eulerian formalism. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailCompléments de C++
Boman, Romain ULg

Scientific conference (2003, November)

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See detailHuman-Visual-System-Based Fusion of Multimodality 3D Neuroimagery using Brain-Shift-Compensating Finite-Element-Based Deformable Models
Verly, Jacques ULg; Vigneron, Lara; Petitjean, Nicolas et al

in Proceedings of SPIE (2003, February), 5029

Our goal is to fuse multimodality imagery to enhance image-guided neurosurgery. Images that need to be fused must be registered. Registration becomes a challenge when the imaged object deforms between the ... [more ▼]

Our goal is to fuse multimodality imagery to enhance image-guided neurosurgery. Images that need to be fused must be registered. Registration becomes a challenge when the imaged object deforms between the times the images to be fused are taken. This is the case when “brain-shift” occurs. We begin by describing our strategy for nonrigid registration via finite-element methods. Then, we independently discuss an image fusion strategy based on a model of the human visual system. We illustrate the operation of many components of the registration system and the operation of the fusion system. [less ▲]

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See detailSimulation of metal forming processes : Numerical aspects of contact and friction
Boman, Romain ULg

Scientific conference (2003, January)

During this presentation, two numerical methods for managing contact in large stresses/strains problems are described: the Lagrange Multipliers method (available in Cast3M - FE code used in LaCaN) and the ... [more ▼]

During this presentation, two numerical methods for managing contact in large stresses/strains problems are described: the Lagrange Multipliers method (available in Cast3M - FE code used in LaCaN) and the penalty method (available in Metafor - FE code used at LTAS-MCT - University of Liège). Contact algorithms can be divided into three steps. The first one - the contact search - is purely geometric and answers the question: which nodes are currently in contact. Main problems and their solutions are discussed. The computation of the normal force is the second step. Non-penetration conditions are applied on the contact nodes. Finally, during the third step, a tangent force due to friction is applied when the nodes are sticking or sliding. Methods are compared in details in the case of metal forming processes. The penalty method seems to be more efficient when a large number of contact nodes are involved during the simulation. The system to be solved is smaller, the convergence is faster and curved analytical surfaces can be easily used for the tools. However, a good penalty coefficient can sometimes be hard to find. As a conclusion, numerical examples coming from Metafor are presented including skin-pass simulation, hydroforming of a tube and blade loss in a aeronautic engine. [less ▲]

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See detailNumerical Simulation of Lubricated Contact in Rolling Processes
Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Journal of Materials Processing Technology (2002), 125-126

In this paper, the lubrication problem in numerical simulation of rolling process is presented. In this case, the recent and complex model of Marsault for the solution of the mixed lubrication regime has ... [more ▼]

In this paper, the lubrication problem in numerical simulation of rolling process is presented. In this case, the recent and complex model of Marsault for the solution of the mixed lubrication regime has been implemented and tested. This model requires the use of the finite difference method to work properly. We will discuss the advantages and the difficulties encountered when trying to solve the same problem with the finite element method in a general frame. Finally, a finite element formulation for the solution of the time-dependent Reynolds' equation coupled with the deformation of the workpiece is proposed. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailNumerical Simulation of Lubricated Contact between Solids in Metal Forming Processes using the Arbitrary Lagrangian Eulerian Formulation
Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Simulation of Material Processing: Theory, Methods and Application: Proceedings of the 7th International Conference NUMIFORM 2001 (2001, June)

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See detailArbitrary Lagrangian Eulerian Method for the Simulation of Lubricated Contact between Solids in Metal Forming Processes
Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Pietryk, Maciej; Kusiak, Jan; Majta, Janusz (Eds.) et al Metal Forming 2000 (2000, September)

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