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Génération d'un maillage pour éléments finis à partir de fichiers de stéréolithographie – Une interface indépendante des formats CAO Béchet, Eric ; ; in Maranzana, Roland (Ed.) De la CAO géométrique vers une CAO fonctionnelle: special cfao au quebec (2003) Detailed reference viewed: 9 (1 ULg)Adaptive mesh generation for mould filling problems in resin transfer moulding Béchet, Eric ; ; et al in Composites : Part A, Applied Science & Manufacturing (2003), 34(9), 813-834 In injection moulding processes such as Resin Transfer Moulding (RTM) for example, numerical simulations are usually performed on a fixed mesh, on which the numerical algorithm predict the displacement of ... [more ▼] In injection moulding processes such as Resin Transfer Moulding (RTM) for example, numerical simulations are usually performed on a fixed mesh, on which the numerical algorithm predict the displacement of the flow front. Error estimations can be used in the numerical algorithm to optimise the mesh for the finite element analysis. The mesh can be also adapted during mould filling to follow the shape of the moving boundary. However, in order to minimize computer time, it is preferable to optimise the mesh before carrying out the filling calculation. In this paper, these ideas are adapted to 3D shells, which represent the most common type of composite parts manufactured by RTM. An error estimator generally used in planar or solid geometries is extended for curved 3D surfaces in the specific case of RTM calculations. The extension consists of a projection of the solution field in the tangent plane to avoid problems related to the curvature of the part. Some other issues specific to shell geometries are pointed out and the results of a filling simulation made on a real part are presented. Non-isothermal filling simulations are also carried out in a rectangular mould to illustrate the stability conditions that arise from the convective heat transfer problem. Finally, an analytical study of radial injections is carried out to illustrate issues related to four types of different mesh refinement procedures: (1) a constant time step, (2) constant radial density (to allow a regular progression of the flow front at each time step), (3) a constant Courant number (to ensure stable thermal simulations); and (4) finally, a constant interpolation error. (C) 2003 Elsevier Ltd. All rights reserved. [less ▲] Detailed reference viewed: 82 (4 ULg)Generation of a finite element MESH from stereolithography (STL) files Béchet, Eric ; ; in Computer-Aided Design (2002), 34(1), 1-17 The aim of the method proposed here is to show the possibility of generating adaptive surface meshes suitable for the finite element method, directly from an approximated boundary representation of an ... [more ▼] The aim of the method proposed here is to show the possibility of generating adaptive surface meshes suitable for the finite element method, directly from an approximated boundary representation of an object created with CAD software. First, we describe the boundary representation, which is composed of a simple triangulation of the surface of the object. Then we will show how to obtain a conforming size-adapted mesh. The size adaptation is made considering geometrical approximation and with respect to an isotropic size map provided by an error estimator. The mesh can be used "as is" for a finite element computation (with shell elements), or can be used as a surface mesh to initiate a volume meshing algorithm (Delaunay or advancing front). The principle used to generate the mesh is based on the Delaunay method, which is associated with refinement algorithms, and smoothing. Finally, we will show that not using the parametric representation of the geometrical model allows us to override some of the limitations of conventional meshing software that is based on an exact representation of the geometry. (C) 2001 Published by Elsevier Science Ltd. [less ▲] Detailed reference viewed: 164 (14 ULg)Maillage adaptatif appliqué au suivi d'un front d'écoulement et application à la fabrication des composites par injection ; Béchet, Eric ; Scientific conference (2002) Detailed reference viewed: 31 (7 ULg)Génération d'un maillage pour éléments finis à partir de fichiers stéréolithographie (STL) : une interface indépendante des formats de CAO Béchet, Eric ; ; in Revue internationale de CFAO et d'informatique graphique (2002), 17/1-2 The aim of the method proposed here is to show the possibility of generating adaptive surface meshes suitable for the finite element method, directly from an approximated boundary representation of an ... [more ▼] The aim of the method proposed here is to show the possibility of generating adaptive surface meshes suitable for the finite element method, directly from an approximated boundary representation of an object created with CAD software. First, we describe the boundary representation, then we will show how to obtain a conforming sizeadapted mesh. The size adaptation is made considering geometrical approximation and with respect to an isotropic size map provided by an error estimator. The principle used to generate the mesh is based on the Delaunay method. Finally, we will show that not using the parametric representation of the geometrical model allows us to override some of the limitations of conventional meshing software that is based on an exact representation of the geometry. [less ▲] Detailed reference viewed: 162 (23 ULg)Re-meshing algorithms applied to Resin Transfer Moulding simulations. Béchet, Eric ; ; et al Scientific conference (2001, August) Today, there are many finite element simulation software on the market. The main issue when developing a new application of the finite element method is not solving the linear systems that arise from the ... [more ▼] Today, there are many finite element simulation software on the market. The main issue when developing a new application of the finite element method is not solving the linear systems that arise from the numerical approximation, but it is rather to construct the mesh and adapt it to the problem. Mesh generation, in the sense of modelling the geometry constraints, still remains a big problem. In this communication, however, we will not deal with initial mesh generation, but rather about mesh modifications applied to a time evolving problem, namely a mould filling simulation. In injection moulding processes, in particular in resin transfer moulding, the simulations are usually preformed with a fixed mesh at each time step. During the displacement of the resin flow, there are phenomena that occur at the front, such as heat transfer. In order to catch them accurately, it is necessary to follow the front flow with the mesh. This implies to implement a re-meshing algorithm. By using this technique, it will be possible to obtain much better results in less time, compared to fixed mesh strategy. The mesh will need to be anisotropic in the vicinity of the front. The size of the mesh along the front is related to the overall accuracy needed for the simulation. The size of the mesh in the perpendicular direction is related to the time accuracy, as the front is moving forward. Those sizes are not related, thus the need for anisotropic mesh procedures is crucial. The mesh will be evolving in the time. For that purpose, we will keep a background isotropic mesh used as starting point for the refinement at every time step. Then, it will be refined anisotropically. The physical field of solution needs to be projected on the new mesh, each time a re-meshing occur. Finally, some validation is needed, first with the standard simulation procedure (without remeshing), then with experimental data. [less ▲] Detailed reference viewed: 78 (7 ULg)Génération de maillages anisotropes à partir de fichiers stéréolithographie Béchet, Eric ; ; Conference (2001) Detailed reference viewed: 16 (3 ULg)Generation of a F.E.M mesh from stereolithography (STL) files Béchet, Eric ; ; Scientific conference (2000) The aim of the method proposed here is to show the possibility of generating adaptive surface meshes suitable for the finite element method, directly from an approximated boundary representation of an ... [more ▼] The aim of the method proposed here is to show the possibility of generating adaptive surface meshes suitable for the finite element method, directly from an approximated boundary representation of an object coming from a Computer Aided Design software. First, we describe this boundary representation, then, we will show how to obtain a conforming, size adapted, mesh. This size adaptation is made with consideration to the geometrical approximation as well as to the respect of an isotropic or anisotropic map, coming from an error estimator. This mesh can be used “as is” for a finite element computation (with shells elements), or be used as to initiate a volume meshing algorithm (Delaunay or advancing front), for 3D simulation. Finally, we will show than the non use of the parametric representation of the geometrical model allows us to do override some limitations of the traditional meshing software based on an exact representation of the geometry. [less ▲] Detailed reference viewed: 253 (11 ULg)Transformation d'un maillage STL pour les méthodes numériques Béchet, Eric ; ; et al Scientific conference (1999) Detailed reference viewed: 13 (2 ULg) |
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