References of "Ponthot, Jean-Philippe"
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See detailFinite element simulation of canine humeral condylar fractures
D'Otreppe, Vinciane ULg; Böhme, Béatrice; Balligand, Marc ULg et al

Conference (2011, July 04)

Humeral condylar fractures are common in dogs. Different types of fractures (lateral, medial, bicondylar) may occur, depending on the age of the dog and the position of its elbow during the impact. The ... [more ▼]

Humeral condylar fractures are common in dogs. Different types of fractures (lateral, medial, bicondylar) may occur, depending on the age of the dog and the position of its elbow during the impact. The goal of this work is to understand the effects of bone posture and skeletal development on canine humeral fractures by means of the finite element method. Four distinct finite element simulations were performed, corresponding to an immature and a mature dog elbow, respectively in extension and flexion. To create the finite element models, subject-specific finite element meshes were extracted from the CT-data. Appropriate material properties were used for cortical bone, trabecular bone and cartilage. The modified Mohr-Coulomb failure criterion was implemented to take account for strength asymmetry. Lateral humeral fractures are obtained for both the young and adult dog elbow, in extension and flexion. This is in agreement with clinical observations, in which lateral condylar fractures are most common. [less ▲]

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See detailDamage and Fracture of Materials Submitted to High Strain Rates. A Thermomechanically Implicit Coupled Approach with Element Erosion
Jeunechamps, Pierre-Paul; Boman, Romain ULg; Papeleux, Luc ULg et al

in Proceedings of the 3rd International Conference on Impact Loading of Lightweight Structures (2011, June 28)

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See detailComparison of Data Transfer Methods between two different meshes
Bussetta, Philippe ULg; Ponthot, Jean-Philippe ULg

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

Many problems solved with the finite element method require more than one mesh (i.e. one specific mesh for each Physic or a remeshing is needed). The Data Transfer Method used, has a great importance in ... [more ▼]

Many problems solved with the finite element method require more than one mesh (i.e. one specific mesh for each Physic or a remeshing is needed). The Data Transfer Method used, has a great importance in the capacity to solve the problem and in the reliability of the solution. In general, the data is composed of two kinds of fields (defined thanks to the nodal values or at the integration points). In this paper, the more used Data Transfer Method is compared with the Data Transfer Methods based on a Weak Form (using Mortar Element or Finite Volume). [less ▲]

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See detailThermomechanical simulation of roll forming process based on the coupling of two independent solvers
Carretta, Yves ULg; Boman, Romain ULg; 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 detailComparaison des outils bibliographiques et bibliométriques Web of Science et Scopus : rapport du groupe de réflexion mis en place par la Bibliothèque Interuniversitaire de la Communauté française de Belgique (BICfB)
Lerinckx, Dominique; Baguet, Muriel; Renaville, François ULg et al

Report (2011)

Depuis 2002, l'ensemble des membres de la BICfB souscrivent au Web of Science (WoS) de Thomson Reuters, plus précisément aux sous-bases Science Citation Index (SCI), Social Sciences Citation Index (SCCI ... [more ▼]

Depuis 2002, l'ensemble des membres de la BICfB souscrivent au Web of Science (WoS) de Thomson Reuters, plus précisément aux sous-bases Science Citation Index (SCI), Social Sciences Citation Index (SCCI) et Arts and Humanities Citation Index (A&HCI). Web of Science, partie du Web of Knowledge (WoK), est une base de données bibliographiques et d'analyse de citations renommée, au départ unique en son genre. Avec le Journal Citation Reports (JCR), elle est également beaucoup utilisée comme base de référence dans l'évaluation des chercheurs et de la recherche. En 2004, deux ressources concurrentes ont vu le jour. Il s'agit de Google Scholar (gratuit mais n'offrant pas autant de fonctionnalités) et de Scopus, un produit Elsevier. Aussi, lors de l'Assemblée générale de la BICfB du 4 mai 2010, les institutions ont décidé de constituer un groupe de réflexion interuniversitaire composé de membres issus des conseils ou administrations de la recherche, de bibliothèques et de représentants du F.R.S.-FNRS afin de comparer en profondeur ces outils. Ce rapport, présenté lors de l'AG du 7 juin 2011 de la BICfB, est le fruit du travail du groupe de réflexion. [less ▲]

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See detailGenerating smooth surface meshes from labelled medical datasets
D'Otreppe, Vinciane ULg; Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Nithiarasu, Perumal; Löhner, Rainald; van Loon, Raoul (Eds.) et al CMBE11: 2nd International Conference on Computational & Mathematical Biomedical Engineering, 30 March - 1 April, 2011, Washington D.C. U.S.A. (2011, March 30)

In this article, an innovative procedure to create high quality triangular meshes from medical scans is proposed. The approach is based on an enhanced Marching Tetrahedra algorithm that extracts a ... [more ▼]

In this article, an innovative procedure to create high quality triangular meshes from medical scans is proposed. The approach is based on an enhanced Marching Tetrahedra algorithm that extracts a consistent multiple region surface mesh from a labelled volume data set; coupled with a surface reconstruction method to avoid typical staircase artifacts. Mesh smoothing and decimation algorithms are also revised to conform to the multiple material nature of the system as well as to adhere to the underlying volume data. The proposed method is well suited for subsequent volume mesh generation and finite element simulations. [less ▲]

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See detailContinuous Roll Forming Simulation using Arbitrary Lagrangian Eulerian Formalism
Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Key Engineering Materials [=KEM] (2011), 473

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See detailApplication of the Arbitrary Lagrangian Eulerian Formalism to Stationary Roll Forming Simulations
Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Advanced Materials Research (2011), 189-193

Due to the length of the mill, accurate modelling of stationary solution of continuous cold roll forming by the finite element method using the classical Lagrangian formulation usually requires a very ... [more ▼]

Due to the length of the mill, accurate modelling of stationary solution of continuous cold roll forming by the finite element method using the classical Lagrangian formulation usually requires a very large mesh leading to huge CPU times. In order to model industrial forming lines including many tools in a reasonable time, the sheet has to be shortened or the element size has to be increased leading to inaccurate results. On top of this, applying loads and boundary conditions on this smaller sheet is usually more difficult than in the continuous case. Moreover, transient dynamic vibrations, which are unnecessarily computed, may appear when the sheet hits each tool, decreasing the convergence rate of the numerical simulation. Beside this classical Lagrangian approach, an alternative method is given by the Arbitrary Lagrangian Eulerian (ALE) formalism which consists in decoupling the motion of the material and the mesh. Starting from an initial guess of the sheet geometry between the rolls, the numerical simulation is performed until the stationary state is reached with a mesh, the nodes of which are fixed in the rolling direction but are free to move on perpendicular plane, following the geometrical boundary of the sheet. The whole forming line can then be modelled using a limited number of brick and contact elements because the mesh is only refined near the tools where bending and contact occur. In this paper, ALE results are compared to previous Lagrangian simulations and experimental measurement on a U-channel, including springback. [less ▲]

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See detailAdvances in Metal Forming Simulation of using Arbitrary Lagrangian Eulerian Formalism
Ponthot, Jean-Philippe ULg; Boman, Romain ULg

in Khan, Akhtar; Meredith, C.; Farrokh, B. (Eds.) Macro to Nano-scale Inelastic Deformation and Failure of Materials & Multi-scale Modeling : Proceedings of PLASTICITY'11, Seventeenth International Symposium on Plasticity and its Current Applications (2011, January)

Accurate modelling of stationary solution of continuous cold roll forming by the finite element method using the classical Lagrangian formulation usually requires a very large mesh leading to huge CPU ... [more ▼]

Accurate modelling of stationary solution of continuous cold roll forming by the finite element method using the classical Lagrangian formulation usually requires a very large mesh leading to huge CPU times. An alternative method is given by the Arbitrary Lagrangian Eulerian (ALE) formalism which consists in decoupling the motion of the material and the mesh. Starting from an initial guess of the sheet geometry between the rolls, the numerical simulation is performed until the stationary state is reached with a mesh. In this paper, ALE results are compared to previous Lagrangian simulations and experimental measurement on a U-channel, including springback [less ▲]

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See detailA non-linear homogeneous model for bone-like materials under compressive load.
Mengoni, Marlène ULg; Voide, Romain; Toye, Dominique ULg et al

in Nithiarasu, P.; Löhner, R.; van Loon, R. (Eds.) et al Conference Proceedings - 2nd International Conference on Computational & Mathematical Biomedical Engineering (2011)

Using morphological data provided by computed tomography, finite element (FE) models can be used to compute the mechanical response of bone and bone-like materials without describing the complex local ... [more ▼]

Using morphological data provided by computed tomography, finite element (FE) models can be used to compute the mechanical response of bone and bone-like materials without describing the complex local microarchitecture. A constitutive law is here developed and proposed for this purpose. It captures the non-linear structural behavior of bone-like materials through the use of fabric tensors. It also allows for irreversible strains using a plastic material model, allowing hardening of the yield parameters. These characteristics are expressed in a constitutive law based on the anisotropic continuum damage theory coupled with isotropic elastoplasticity in a finite strains framework. This law is implemented into Metafor, a non-linear FE software. Simulations of cylindrical samples undergoing stepwise compression are presented. [less ▲]

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See detailOn the periodontal ligament representation in orthodontic tooth movement modelisation
Mengoni, Marlène ULg; Ponthot, Jean-Philippe ULg

Conference (2011)

Orthodontic tooth movement (OTM) is the result of bone remodeling at the interface with the periodontal ligament (PDL) around a mechanically loaded tooth in response to a biomechanical stimulus. Modeling ... [more ▼]

Orthodontic tooth movement (OTM) is the result of bone remodeling at the interface with the periodontal ligament (PDL) around a mechanically loaded tooth in response to a biomechanical stimulus. Modeling of the PDL therefore plays an important role in the process of modeling OTM. However when producing a finite element model from clinical computer tomography data, the PDL cannot be segmented and its geometry is approximated by many authors from the root geometry. The aim of this study is to propose alternatives to a geometrical representation of the PDL using either simple spring elements between the teeth and alveolar bone or bilateral sticking contact conditions. Results consist in a comparison of the hydrostatic and Von-Mises stresses in the bone along the root as well as the strain energy used in a bone remodeling algorithm when a 1N force is applied to a single rooted tooth crown. While both models can well represent the pressure (hydrostatic stress) transfer from the tooth to the bone, the bilateral sticking contact conditions show better results to transfer the shear stress as well as the strain energy. [less ▲]

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See detailNumerical Simulations of Asperity Crushing - Application to Cold Rolling
Carretta, Yves ULg; 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 ▲]

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See detailNUMERICAL SIMULATIONS OF THIXOFORMING PROCESSES: DEVELOPMENT AND COMPARISON OF SEVERAL SEMI-SOLID CONSTITUTIVE LAWS
Koeune, Roxane ULg; Ponthot, Jean-Philippe ULg

(2011)

ABSTRACT This paper deals with the development, and the comparison, of several constitutive laws in the frame of the simulation of thixoforming processes. The comparison is based on the simulation of a ... [more ▼]

ABSTRACT This paper deals with the development, and the comparison, of several constitutive laws in the frame of the simulation of thixoforming processes. The comparison is based on the simulation of a simple academic test that is well representative of the thixotropic behavior: a simple shear test, with shear-rate step-up and step-down. [less ▲]

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See detailMultiple material mesh generation for biomedical applications
D'Otreppe, Vinciane ULg; Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Proceedings of the 9th belgian day on biomedical engineering (2010, November 26)

The finite element method is commonly used in biomedical applications for the simulation of the behaviour of biological structures. However, extracting finite element meshes from medical images is still ... [more ▼]

The finite element method is commonly used in biomedical applications for the simulation of the behaviour of biological structures. However, extracting finite element meshes from medical images is still very challenging. We propose an innovative system to create accurate multiple domain tetrahedral meshes from medical images. Our approach is based on an enhanced Marching Tetrahedra algorithm that extracts the boundary surfaces delimiting the different material domains in an integrated manner. Moreover, a surface reconstruction method is employed to ensure that the resulting mesh is a smooth and accurate surface representation of the original sampled structure. Mesh smoothing and decimation algorithms are also revised to conform to the multiple material nature of the system as well as to adhere to the underlying volume data. [less ▲]

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See detailMultiple Material Mesh Generation For Biomedical Applications
D'Otreppe, Vinciane ULg; Boman, Romain ULg; Ponthot, Jean-Philippe ULg

Poster (2010, November 26)

The finite element (FE) method is commonly used in biomedical applications for the simulation of the behaviour of biological structures. A key component in FE simulation is the creation of a finite ... [more ▼]

The finite element (FE) method is commonly used in biomedical applications for the simulation of the behaviour of biological structures. A key component in FE simulation is the creation of a finite element mesh. In medical applications, the meshes should be directly generated from the medical scans. Moreover, biological structures are usually composed of several inner regions that need to be separately segmented, labelled and meshed to be able to apply different material properties in the finite element model. A procedure to create surface meshes from a multi-valued volume data sets is proposed. Following properties are guaranteed: (1) The generated mesh consists of a set of non manifold triangle meshes that separate each connected component in the labelled data set. These interface meshes join each other consistently along their boundaries, i.e., no T junctions nor gaps may appear. (2) The surface mesh is a geometrically accurate representation of the data represented in the medical scans. However, it is not be tainted by the typical aliasing and staircase artifacts that are due to the discrete nature of the voxels. [less ▲]

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See detailEnhanced FEM-based Modeling of Brain Shift Deformation in Image-Guided Neurosurgery
Vigneron, Lara M.; Boman, Romain ULg; Ponthot, Jean-Philippe ULg et al

in Journal of Computational & Applied Mathematics (2010), 234

We consider the problem of improving outcomes for neurosurgery patients by enhancing intraoperative navigation and guidance. Current navigation systems do not accurately account for intraoperative brain ... [more ▼]

We consider the problem of improving outcomes for neurosurgery patients by enhancing intraoperative navigation and guidance. Current navigation systems do not accurately account for intraoperative brain deformation. We focus on the brain shift deformation that occurs just after the opening of the skull and dura. The heart of our system is a nonrigid registration technique using a biomechanical model. We specifically work on two axes: the representation of the structures in the biomechanical model and the evaluation of the surface landmark displacement fields between intraoperative MR images. Using the modified Hausdorff distance as an image similarity measure, we demonstrate that our approach significantly improves the alignment of the intraoperative images. ' 2009 Elsevier B.V. All rights reserved. [less ▲]

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