References of "Ponthot, Jean-Philippe"
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See detailFree-slip boundary conditions for simulating free-surface incompressible flows through the Particle Finite Element Method
Cerquaglia, Marco Lucio ULg; Deliège, Geoffrey ULg; Boman, Romain ULg et al

in International Journal for Numerical Methods in Engineering (in press)

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See detailPreliminary assessment of the possibilities of the Particle Finite Element Method in the numerical simulation of bird impact on aeronautical structures
Cerquaglia, Marco Lucio ULg; Deliège, Geoffrey ULg; Boman, Romain ULg et al

in Procedia Engineering (in press)

As well known, in the analysis of bird impact events the bird is often reduced, even experimentally, to a surrogate projectile modeled as a weakly compressible fluid (typically a mixture of water and air ... [more ▼]

As well known, in the analysis of bird impact events the bird is often reduced, even experimentally, to a surrogate projectile modeled as a weakly compressible fluid (typically a mixture of water and air). From a numerical standpoint, the presence of a free surface and the strong interaction with the aircraft structures represent a limit for traditional computational fluid dynamics methods based on an Eulerian grid. On the other hand, classical Lagrangian methods cannot cope with the extremely large deformations experienced by the projectile during the impact. The Particle Finite Element Method (PFEM) is a Lagrangian particle method that can account for very large deformations, preserving the robustness and generality of the finite element method, and thus owning a key advantage over other approaches, e.g. Smoothed Particle Hydrodynamics (SPH), usually cursed with consistency and stability issues. To assess the possibilities of the method in the context of bird impact, theoretical analyses are initially performed based on the impact of a water jet on a rigid surface. Then, the influence of the geometry of a more realistic projectile is analyzed and the capability of the method to take into account separation and fragmentation is highlighted. [less ▲]

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

in Tribology International (in press)

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 detailNumerical Methods
Agelet de Saracibar, Carlos; Boman, Romain ULg; Bussetta, Philippe et al

in Schmitz, Georg; Prahl, Ulrich (Eds.) Handbook of Software Solutions for ICME, (2017)

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See detailApplication of Uncoupled Damage Models to Predict Ductile Fracture in Sheet Metal Blanking
Canales Cardenas, Cristian ULg; Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Key Engineering Materials (2016), 725

The use of uncoupled damage models has been widely used over the years for the prediction of ductile fracture in engineering applications. Nevertheless, its applicability in the prediction of failure has ... [more ▼]

The use of uncoupled damage models has been widely used over the years for the prediction of ductile fracture in engineering applications. Nevertheless, its applicability in the prediction of failure has been shown to be limited in the wide range of loading conditions encountered in different manufacturing processes. In order to enhance the formulation of former damage models, the Lode angle has been recently used to characterize the stress states along with the stress triaxiality. This new family of damage models has been demonstrated to give excellent results when proportional loading paths are considered, but its efficiency in more complex applications still need further analysis. To this end, a comparative study of former and recently developed uncoupled damage models is performed in this work. The identification of material parameters is done considering simple mechanical tests under different conditions. Then, the models are used to predict the onset and propagation of cracks during blanking, where numerical predictions are compared with experimental results. Finally, the selected damage models presented a remarkable overall performance in the range of clearances under study. [less ▲]

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See detailDEM modeling of ball mills with experimental validation: influence of contact parameters on charge motion and power draw
Boemer, Dominik ULg; Ponthot, Jean-Philippe ULg

in Computational Particle Mechanics (2016), 4(1), 53-67

Discrete element method simulations of a 1:5-scale laboratory ball mill are presented in this paper to study the influence of the contact parameters on the charge motion and the power draw. The position ... [more ▼]

Discrete element method simulations of a 1:5-scale laboratory ball mill are presented in this paper to study the influence of the contact parameters on the charge motion and the power draw. The position density limit is introduced as an efficient mathematical tool to describe and to compare the macroscopic charge motion in different scenarios, i.a. with different values of the contact parameters. While the charge motion and the power draw are relatively insensitive to the stiffness and the damping coefficient of the linear spring-slider-damper contact law, the coefficient of friction has a strong influence since it controls the sliding propensity of the charge. Based on the experimental calibration and validation by charge motion photographs and power draw measurements, the descriptive and predictive capabilities of the position density limit and the discrete element method are demonstrated, i.e. the real position of the charge is precisely delimited by the respective position density limit and the power draw can be predicted with an accuracy of about 5 %. [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 detailNumerical Simulations of a Two Roll Round Bar Straightener
Flipon, Baptiste; Lawrjaniec, Didier; Papeleux, Luc ULg et al

in AIP Conference Proceedings 1769, 120001 (2016); (2016, April 28)

A 2-roll bar straightener is a finishing process applied after the rolling operation of round steel bars. During the straightening, the bar rotation is induced by the two rotating rolls. It also undergoes ... [more ▼]

A 2-roll bar straightener is a finishing process applied after the rolling operation of round steel bars. During the straightening, the bar rotation is induced by the two rotating rolls. It also undergoes an alternate bending in such a way that the bar section is finally deformed uniformly. The purpose of this process is to correct the curvature defaults of the rolled bar. Indeed, the bar must be straight before being sent to the client and a straightened uniform surface layer is appreciated. With the apparition of new grades and also new diameters of steel round bars, it becomes essential to better understand the straightening process in order to (i) have a better knowledge of what the round bar undergoes during the process, (ii) precisely understand the straightening process, the effect of each component and the process parameters. [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 detailA numerical study of hypoelastic and hyperelastic large strain viscoplastic Perzyna type models
Careglio, Claudio; Canales Cardenas, Cristian ULg; García Garino, Carlos et al

in Acta Mechanica (2016)

For the case ofmetalswith large viscoplastic strains, it is necessary to define appropriate constitutive models in order to obtain reliable results from the simulations. In this paper, two large strain ... [more ▼]

For the case ofmetalswith large viscoplastic strains, it is necessary to define appropriate constitutive models in order to obtain reliable results from the simulations. In this paper, two large strain viscoplastic Perzyna type models are considered. The first constitutive model has been proposed by Ponthot, and the elastic response is based on hypoelasticity. In this case, the kinematics of the constitutive model is based on the additive decomposition of the rate deformation tensor. The second constitutive model has been proposed by García Garino et al., and the elastic response is based on hyperelasticity. In this case, the kinematics of the constitutive model is based on the multiplicative decomposition of the deformation gradient tensor. In both cases, the resultant numerical models have been implemented in updated Lagrangian formulation. In this work, global and local numerical results of the mechanical response of both constitutive models are analyzed and discussed. To this end, numerical experiments are performed and different parameters of the constitutive models are tested in order to study the sensitivity of the resultant algorithms. In particular, the evolution of the reaction forces, the effective plastic strain, the deformed shapes and the sensitivity of the numerical results to the finite element mesh discretization have been compared and analyzed. The obtained results show that both models have a very good agreement and represent very well the characteristic of the viscoplastic constitutive model. [less ▲]

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See detailPrediction of the mechanical response of canine humerus to three-point bending using subject-specific finite element modelling
Laurent, Cédric; Böhme, Béatrice ULg; Mengoni, Marlène ULg et al

in Proceedings of the Institution of Mechanical Engineers - Part H - Journal of Engineering in Medicine (2016), 230

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See detailTwo 3D thermomechanical numerical models of friction stir welding processes with a trigonal pin
Bussetta, Philippe; Feulvarch, Eric; Tongne, Amèvi et al

in Numerical Heat Transfer : Part A. Applications (2016), 70(9), 995-1008

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See detailNumerical prediction of ductile failure in the blanking process by means of uncoupled and coupled phenomenological damage models
Canales Cardenas, Cristian ULg; Ponthot, Jean-Philippe ULg

in MATEC Web of Conferences (2016)

Fracture prediction in blanking has gained great attention due to increasing requirements of high-quality products. In this work, the predictive capabilities of different uncoupled and coupled damage ... [more ▼]

Fracture prediction in blanking has gained great attention due to increasing requirements of high-quality products. In this work, the predictive capabilities of different uncoupled and coupled damage models, recently implemented in a fully implicit homemade FE code, for blanking process are compared. Some advanced models considered here include damage sensitivity to both triaxiality and Lode angle in their formulation. The material characterization is based on the history of internal variables during loading, where different mechanical tests are considered. Finally, numerical and experimental results are compared for a wide range of different geometries of blanking. [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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