References of "Boman, Romain"
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See detailDévelopper du code avec une équipe de "non-geeks" à l'ULg
Boman, Romain ULg

Speech/Talk (2016)

Cette présentation a été faite aux "Geeks Anonymes" de l'Université de Liège le 17 juin 2016. J'y présente les techniques de développement de logiciels vers lesquelles notre groupe de recherche a convergé ... [more ▼]

Cette présentation a été faite aux "Geeks Anonymes" de l'Université de Liège le 17 juin 2016. J'y présente les techniques de développement de logiciels vers lesquelles notre groupe de recherche a convergé après 20 ans de pratique. En particulier, je détaille les compromis qui ont dû être trouvés pour aider les thésards et ingénieurs de recherche peu à l'aise avec l'informatique. [less ▲]

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See detailTwo novel ways to impose free-slip boundary conditions in fluid-structure interaction problems using the Particle Finite Element Method
Cerquaglia, Marco Lucio ULg; Deliège, Geoffrey ULg; Boman, Romain ULg et al

Conference (2016, June 09)

As well known, the imposition of boundary conditions is, in many cases, the trickiest part in solving differential problems, both from a physical and numerical standpoint. This work focuses on the way ... [more ▼]

As well known, the imposition of boundary conditions is, in many cases, the trickiest part in solving differential problems, both from a physical and numerical standpoint. This work focuses on the way boundary conditions are accounted for in the solution of fluid-structure interaction problems using the Particle Finite Element Method (PFEM). In particular, the PFEM traditionally employs no-slip conditions on the fluid-solid interfaces. Our aim is twofold. On the one hand, we demonstrate that, in the framework of the PFEM, the no-slip hypothesis is too strong in some cases, leading to erroneous physical results, and that a free-slip condition is to be preferred instead; we therefore propose two novel ways to impose free-slip conditions, devoting special attention to generality, simplicity and robustness. On the other hand, we show how the use of free-slip boundary conditions can also be beneficial with regards to two major problems arising from the remeshing procedure employed by the PFEM: the violation of the mass conservation principle and the introduction of spurious pressure oscillations. [less ▲]

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See detailLagrangian and arbitrary Lagrangian Eulerian simulations of complex roll-forming processes
Crutzen, Yanick ULg; Boman, Romain ULg; Papeleux, Luc ULg et al

in Comptes Rendus Mécanique (2016), 344(4-5), 251-266

The Arbitrary Lagrangian Eulerian (ALE) formalism is a breakthrough technique in the numerical simulation of the continuous-type roll-forming process. In contrast to the classical Lagrangian approach, the ... [more ▼]

The Arbitrary Lagrangian Eulerian (ALE) formalism is a breakthrough technique in the numerical simulation of the continuous-type roll-forming process. In contrast to the classical Lagrangian approach, the ALE formalism can compute the hopefully stationary state for the entire mill length with definitely effortless set-up tasks thanks to a nearly-stationary mesh. In this paper, advantages of ALE and Lagrangian formalisms are extensively discussed for simulating such continuous-type processes. Through a highly complex industrial application, the ease of use of ALE modelling is illustrated with the in-house code METAFOR. ALE and Lagrangian results are in good agreement with each other. [less ▲]

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See detailMesh Management Methods in Finite Element Simulations of Orthodontic Tooth Movement
Mengoni, Marlène ULg; Ponthot, Jean-Philippe ULg; Boman, Romain ULg

in Medical Engineering & Physics (2016), 38(2), 140-147

In finite element simulations of orthodontic tooth movement, one of the challenges is to represent long term tooth movement. Large deformation of the periodontal ligament and large tooth displacment due ... [more ▼]

In finite element simulations of orthodontic tooth movement, one of the challenges is to represent long term tooth movement. Large deformation of the periodontal ligament and large tooth displacment due to bone remodelling lead to large distortions of the finite element mesh when a Lagrangian formalism is used. We propose in this work to use an Arbitrary Lagrangian Eulerian (ALE) formalism to delay remeshing operations. A large tooth displacement is obtained including effect of remodelling without the need of remeshing steps but keeping a good-quality mesh. Very large deformations in soft tissues such as the periodontal ligament is obtained using a combination of the ALE formalism used continuously and a remeshing algorithm used when needed. This work demonstrates that the ALE formalism is a very efficient way to delay remeshing operations. [less ▲]

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See detailComparison of residual stresses on long rolled profiles measured by X-ray diffraction, ring core and the sectioning methods and simulated by FE method
Bouffioux, Chantal ULg; Pesci, Raphaël; Boman, Romain ULg et al

in Thin-Walled Structures (2016), 104

Sheet piles are produced by hot rolling, a cooling step and, if required, by a straightening operation. Numerical simulations indicate that the stress field is almost homogeneous through the thickness ... [more ▼]

Sheet piles are produced by hot rolling, a cooling step and, if required, by a straightening operation. Numerical simulations indicate that the stress field is almost homogeneous through the thickness, justifying the comparison of X-ray diffraction, ring core and the sectioning methods applied after the cooling step and after the straightening process. The equipment, the steps of the experimental procedures and the results are detailed, showing the limits, the specificities and the advantages of each method. Moreover, the amplitude and the distribution of the stresses along the width of the sections present good agreement with results of numerical simulations. [less ▲]

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See detail3D numerical models using a fluid or a solid formulation of FSW processes with non-cylindrical pin
Bussetta, Philippe; Dialmi, Narges; Chiumenti, Michele et al

in Advanced Modeling and Simulation in Engineering Sciences (2015), 2(27),

Friction Stir Welding (FSW) process is a relatively recent welding process (patented in 1991). FSW is a solid-state joining process during which materials to be joined are not melted. During the FSW ... [more ▼]

Friction Stir Welding (FSW) process is a relatively recent welding process (patented in 1991). FSW is a solid-state joining process during which materials to be joined are not melted. During the FSW process, the behavior of the material is at the interface between solid mechanics and fluid mechanics. In this paper, a 3D numerical model of the FSW process with a non-cylindrical tool based on a solid formulation is compared to another one based on a fluid formulation. Both models use advanced numerical techniques such as the Arbitrary Lagrangian Eulerian (ALE) formulation, remeshing or the Orthogonal Sub-Grid Scale method (OSS). It is shown that these two formulations essentially deliver the same results. [less ▲]

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See detailFinite element modelling of composite structures under crushing load
Chiu, Louis N.S.; Falzon, Brian G.; Boman, Romain ULg et al

in Composite Structures (2015), 131

This paper details the theory and implementation of a composite damage model, addressing damage within a ply (intralaminar) and delamination (interlaminar), developed for the simulation of the crushing of ... [more ▼]

This paper details the theory and implementation of a composite damage model, addressing damage within a ply (intralaminar) and delamination (interlaminar), developed for the simulation of the crushing of laminated composite structures. It includes a more accurate determination of the characteristic length to achieve mesh objectivity in capturing intralaminar damage consisting of matrix cracking and fibre failure, a load-history dependent material response, an isotropic hardening nonlinear matrix response, as well as a more physically-based interactive matrix damage mechanism. The developed damage model requires a set of material parameters obtained from a combination of standard and non-standard material characterisation tests. The fidelity of the model mitigates the need to manipulate, or “calibrate”, the input data to achieve good agreement with experimental results. This intralaminar damage model was implemented as a VUMAT subroutine, and used in conjunction with an existing interlaminar damage model, in Abaqus/Explicit. This approach was validated through the simulation of the crushing of a cross-ply composite tube with a tulip-shaped trigger, loaded in uniaxial compression. Despite the complexity of the chosen geometry, excellent correlation was achieved with experimental results. [less ▲]

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See detailLagrangian and Arbitrary Lagrangian Eulerian Simulations of Complex Roll Forming Processes
Crutzen, Yanick ULg; Boman, Romain ULg; Papeleux, Luc ULg et al

Conference (2015, July)

Finite element simulation of the roll forming process is regarded as an essential tool for the early design and optimization stages of a roll forming mill. However, such simulations are generally ... [more ▼]

Finite element simulation of the roll forming process is regarded as an essential tool for the early design and optimization stages of a roll forming mill. However, such simulations are generally incredibly time-consuming, limited to some simple cases and to the pre-cut forming method. In contrast to the classical Lagrangian approach, the Arbitrary Lagrangian Eulerian (ALE) formalism, which consists in decoupling the motion of the material and the mesh, can simulate the continuous process for the entire roll forming line at reasonable CPU cost by using a nearly-stationary mesh. In this work, the numerical results are compared to some experimental data on a U-channel in order to validate both Lagrangian and ALE models using our in-house code METAFOR. Furthermore, advantages of the ALE formalism are highlighted with the simulation of a tubular rocker panel on a 16-stand forming mill, which is a real industrial mill. [less ▲]

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See detailComparison of fracture prediction models on sheet metal blanking simulations
Canales Cardenas, Cristian ULg; Boman, Romain ULg; Bussetta et al

Conference (2015, July)

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See detailA Low-Cost Digital Image Correlation Technique for Characterising the Shear Deformation of Fabrics for Draping Studies
Pierce, R. S.; Falzon, B. G.; Thompson, M. C. et al

in Strain (2015), 51(3), 180-189

A novel digital image correlation (DIC) technique has been developed to track changes in textile yarn orientations during shear characterisation experiments, requiring only low-cost digital imaging ... [more ▼]

A novel digital image correlation (DIC) technique has been developed to track changes in textile yarn orientations during shear characterisation experiments, requiring only low-cost digital imaging equipment. Fabric shear angles and effective yarn strains are calculated and visualised using this new DIC technique for bias extension testing of an aerospace grade, carbon-fibre reinforcement material with a plain weave architecture. The DIC results are validated by direct measurement, and the use of a wide bias extension sample is evaluated against a more commonly used narrow sample. Wide samples exhibit a shear angle range 25% greater than narrow samples and peak loads which are 10 times higher. This is primarily due to excessive yarn slippage in the narrow samples; hence, the wide sample configuration is recommended for characterisation of shear properties which are required for accurate modelling of textile draping [less ▲]

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See detailSimulations lagrangienne et arbitraire lagrangienne eulérienne du procédé de profilage
Crutzen, Yanick ULg; Boman, Romain ULg; Papeleux, Luc ULg et al

in Actes du 12e Colloque National en Calcul des Structures (2015, May)

L’application du formalisme Arbitraire Lagrangien Eulérien (ALE) à la simulation numérique du procédé de profilage permet de calculer l’état espéré stationnaire du procédé de type continu en modélisant de ... [more ▼]

L’application du formalisme Arbitraire Lagrangien Eulérien (ALE) à la simulation numérique du procédé de profilage permet de calculer l’état espéré stationnaire du procédé de type continu en modélisant de manière efficace l’intégralité de la ligne grâce à un maillage quasi-Eulérien. Ce type de simulation sera comparé à l’approche classique en formalisme Lagrangien dans le cadre d’une application industrielle de profilage. Les performances de la parallélisation de l’algorithme ALE seront analysées dans l’état actuel des développements du code de calcul METAFOR. [less ▲]

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See detailNumerical prediction of resulting rollover shapes and sheared edges after blanking process
Canales Cardenas, Cristian ULg; Boman, Romain ULg; Bussetta, Philippe et al

Conference (2015, April)

Over the years, the simulation of manufacturing processes has introduced several numerical challenges for researchers in computational mechanics. In particular, the numerical modeling of sheet metal ... [more ▼]

Over the years, the simulation of manufacturing processes has introduced several numerical challenges for researchers in computational mechanics. In particular, the numerical modeling of sheet metal blanking process involves different numerical issues that must be carefully treated: a large and highly localized deformation in the shearing zone prior to fracture, complex contact interactions between the tools and the metallic sheet and finally, the ductile failure phenomenon. Despite that this process is one of the most widely used cutting techniques for mass production, the process parameters are normally set by empirical evidence due to the physical complexity resulting from the extreme amount of shearing involved. In addition, the strain-rate dependent behavior of the material must be taken into account due to high punch velocities encountered in practice. Thus, an accurate numerical tool is extremely desirable to optimize the setting parameters of this technique and will lead to a better understanding of the process. [less ▲]

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See detailOn some drawbacks and possible improvements of a Lagrangian finite element approach for simulating incompressible flows
Cerquaglia, Marco Lucio ULg; Deliège, Geoffrey ULg; Boman, Romain ULg et al

in Oñate, E.; Bischoff, M.; Owen, D.R.J. (Eds.) et al Proceedings of the IV International Conference on Particle-Based Methods – Fundamentals and Applications (2015)

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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 detailEfficient 3D transfer operators based on numerical integration
Bussetta, Philippe ULg; Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in International Journal for Numerical Methods in Engineering (2015), 102(3-4), 892-929

This paper deals with data transfer between two meshes as it happens in a finite element context when a remeshing has to be performed. We propose a finite-volume-based data transfer method for an ... [more ▼]

This paper deals with data transfer between two meshes as it happens in a finite element context when a remeshing has to be performed. We propose a finite-volume-based data transfer method for an efficient remeshing of three-dimensional solid mechanics problems. The originality of this transfer method stems from a linear reconstruction of the fields to be transferred on an auxiliary finite volume mesh, a fast computation of the transfer operator and the application to the complete remeshing of 3D problems. This procedure is applicable to both nodal values and discrete fields defined at quadrature points. In addition, a data transfer method using mortar elements is presented. The main improvement made to this second method comes from a fast computation of mortar elements. These two data transfer methods are compared with the simplest transfer method, which consists of a classical interpolation. After some academic examples, we present 2D forging and 3D friction stir welding applications. [less ▲]

Detailed reference viewed: 64 (10 ULg)