Maire L.,MINES ParisTech |
Scholtes B.,MINES ParisTech |
Moussa C.,MINES ParisTech |
Bozzolo N.,MINES ParisTech |
And 3 more authors.
Materials and Design | Year: 2017
This paper describes a level set framework for the full field modeling of dynamic and post-dynamic recrystallization in a 3D polycrystalline material with an accurate description of grains topology at large deformation and application to 304L austenitic stainless steel. Topological evolutions are simulated based on a kinetic law linking the velocity of the boundaries to the thermodynamic driving forces. Recrystallization is modeled by coupling a level set approach to phenomenological laws describing strain hardening mechanism and nucleation criteria. Although the proposed formalism does not consider crystal plasticity because of its computational costs, it enables to reach outstanding dynamic recrystallization computations in a front-capturing finite element framework comparatively to the state of art. © 2017 Elsevier Ltd
Wey E.,TRANSVALOR S.A. |
Schroedter-Homscheidt M.,German Aerospace Center
Energy Procedia | Year: 2013
In order to assess the potential electricity production of a solar plant, industry usually uses long term time series of irradiation data. In addition to this, it is possible to obtain from long term satellite images a statistical description of the clouds in the zone of interest. As the clouds are one of the main influencing parameters to the solar irradiation, this additional information can be very valuable to understand location-dependent characteristics when selecting a solar generator's location and to decide on the type of technology most appropriate for the site. The APOLLO (AVHRR Processing scheme Over cLouds Land and Ocean, originally developed for the AVHRR instrument) methodology delivers cloud mask, cloud classification, cloud optical depth, and cloud top temperature as cloud physical parameters for all MSG (Meteosat Second Generation) SEVIRI (Spinning Enhanced Visible and InfraRed Imager) pixels with a temporal resolution of 15 minutes during daytime since 1st February 2004. Based on a long term result of APOLLO at a given point, we introduce a new use of this data, the APOLLO Cloud Product Statistics, to determine the typical cloud situations and spatio-temporal patterns at the location of interest. Together with state of the art solar irradiation estimations, these statistical results can be used to determine several important factors for the choice of the best suited solar technology to use. In the main section, the statistics at the pixel location and in a 49×49 pixel zone around the point are described for a one year time series. Examples of the use of these statistical results are presented to better understand the type of sky patterns at the location. © 2013 The Authors.
Cao T.-S.,MINES ParisTech |
Maire E.,CNRS Laboratory for Materials: Engineering and Science |
Verdu C.,CNRS Laboratory for Materials: Engineering and Science |
Bobadilla C.,ArcelorMittal |
And 3 more authors.
Computational Materials Science | Year: 2014
The present paper deals with the identification of the parameters of a generalized GTN model and the characterization of ductile damage for a high carbon steel by both X-ray micro-tomography and "macroscopic" mechanical tests. First, in situ X-ray micro-tomography tensile tests are performed and the results are used for the modeling of ductile damage mechanisms (voids nucleation, growth and coalescence) using analytical formulations. Interrupted in situ SEM tensile test is also carried out to examine the microstructure evolution. The damage process during in situ X-ray micro-tomography tensile tests is the result of continuous nucleation of small voids and significant growth of large voids; whereas the coalescence takes place locally. In addition, tomography results combined with the results of macroscopic mechanical tests at different loading configurations are used to identify the Gurson-Tvergaard-Needleman model extended for shear loading by Xue (2008). It proved necessary to propose an improvement to account for the influence of the stress triaxiality level on the nucleation formulation of the GTN model. This new formulation is then identified via experimental tests. The results show that, with the parameters obtained from both microstructure measurements and macroscopic considerations, the modified GTN model can reproduce quite accurately the experimental results for different loading configurations. © 2013 Elsevier B.V. All rights reserved.
Agency: European Commission | Branch: FP7 | Program: CP | Phase: SPA.2010.1.1-01 | Award Amount: 3.18M | Year: 2011
The project ENDORSE aims at a user-driven development of downstream services in renewable energies by exploiting the GMES Core Services (MACC, SAFER and Geoland 2) together with other EO/in-situ data and modelling. It addresses regional services promoting the energy use from sun, wind, and biomass, electricity grid management and building engineering through daylighting in buildings. The consortium has teamed with relevant users to stimulate the development of sustainable and transferable downstream services. ENDORSE will 1) develop and validate pre-market downstream services in collaboration with well-defined end-users by performing R&D activities; 2) assess the conditions for self-sustainability of these services through surveys and workshops with end-users; 3) disseminate the achievements of the project to foster the use of Core Services data and other EO data by the renewable energies community; 4) stimulate the market of downstream services in renewable energies towards the end-users community, and the development of such services by SMEs and other service-oriented companies by demonstrating precursors with documented conditions of sustainability. The expected major outcomes of ENDORSE are 1) scientific advances in assessment of surface air temperature and solar radiation, and data fusion; 2) a set of validated and documented innovative methods exploiting Core Services data and other EO data; 3) a portfolio of pre-market services, serving as precursors and examples of best practices for similar downstream services (other regions, other providers), with documented conditions of sustainability; 4) a stimulation of the renewable energies community towards exploitation of Core Services data and other EO data; 5) a stimulation of the service industry towards development of downstream services; 6) feedbacks to Core Services on their data, and as a whole to GMES and GEOSS on the exploitation of EO data in renewable energies area.
Jaouen O.,Transvalor S.A. |
Costes F.,Transvalor S.A. |
Francois G.,Transvalor S.A.
Proceedings of the 6th International Congress on the Science and Technology of Steelmaking, ICS 2015 | Year: 2015
It is well known now that the ingot defects like hot tears or cracks are rooted at the first beginning of the solid shell birth. Damages result from the competition between hydrostatic pressure within the turbulent flow of the liquid zone and the solidifying skin under tensile stresses and strains state. In addition, the thermal energy extracted from the cast product by the mold has huge impact of the thickness of the shell. It depends on the air gap growth issued from the shrinkage of the solidifying metal together with the deformation of the mold components. Numerically speaking, the method able at taking all that phenomena into account through an accurate way is a fluid/structure model. Indeed, a standard CFD method does not represent the solid behavior, so that the stresses, strains, air gap evolution due to the shrinkage of the shell are not reachable. In that paper, a new 3D fluid/structure model involving the turbulent fluid flow and the solid constitutive equation is described. The management of the dedicated "liquid time step" allowing high velocity motion into the liquid phase of the alloy coupled with the "solid time step" dealing with the solid phase and the corresponding slow motion, is described. An application on an ingot casting process taken into account the coupling with the deformation of the mold is presented. Moreover, based on that model, it is shown that the segregation within the ingot is tracked. In addition, the top powder is accounted as deformable body following the shrinkage of the top surface of the ingot. The exothermic reaction is considered as well in order to estimate its impact on the cooling time and the final quality of the cast product.
De Micheli P.,TRANSVALOR S.A. |
Perchat E.,TRANSVALOR S.A. |
Ducloux R.,TRANSVALOR S.A. |
Digonnet H.,MINES ParisTech |
Fourment L.,MINES ParisTech
Key Engineering Materials | Year: 2013
Improvements in parallel computing and adaptive remeshing have permitted to simulate a wide range of metal forming processes within few hours or days on modern multi-core workstations. However, they do not tackle the issues encountered in incremental forming processes, making them very challenging. Multi-mesh methods opens very interesting doors in this domain, making possible to take advantage of adaptive remeshing techniques (optimizing the ratio precision/cost) without its usual drawbacks (loss of information and diffusion issues). We present in this article a fully parallel Dual-Mesh implementation in the commercial FEA software FORGE®, compatible with a wide range of other FEM facilities. Speed-up larger than 4 are common for incremental forming simulations, and speed-up larger than 10 can be reached in favorable cases. Parallel efficiency is the same than for our standard computations (>80% for more than 2000 nodes per core). Copyright © 2013 Trans Tech Publications Ltd.
Francois G.,TRANSVALOR S.A. |
Ville L.,TRANSVALOR S.A. |
Silva L.,MINES ParisTech |
Vincent M.,MINES ParisTech
Key Engineering Materials | Year: 2013
In this paper, we present an innovative adaptive meshing method developed in the injection simulation software Rem3D®. This method generates a full optimized mesh with a high accuracy for strong flow/heat/rheology coupling as well for complex interface evolutions, and with a reduced number of nodes. Results show good agreement with analytical solutions, as well as for full industrial process experiments. Copyright © 2013 Trans Tech Publications Ltd.
Scholtes B.,French National Center for Scientific Research |
Scholtes B.,Transvalor S.A. |
Shakoor M.,French National Center for Scientific Research |
Settefrati A.,Transvalor S.A. |
And 3 more authors.
Computational Materials Science | Year: 2015
Recently a new numerical model devoted to the full field modeling of microstructural evolutions at the polycrystal scale has been proposed and validated . The latter is based on a level set description of interfaces in a finite element framework. Firstly introduced to model 2D and 3D primary recrystallization with nucleaction [1,2], it has then been extended to consider the grain growth stage [3,4]. The ability of this approach to model the Zener pinning phenomenon without any assumption concerning the shape of second phase particles was also demonstrated . This model has nevertheless an elevated computational cost and requires many numerical parameters whose calibration is not straightforward. In the present paper, some major improvements of the model which address these two points are discussed. A comparative study is also provided in order to illustrate the gains achieved in terms of computational efficiency and robustness. © 2015 Elsevier B.V.
Sartori A.,Muraro Spa |
Lasne P.,Transvalor S.A. |
Gabrielli M.,Enginsoft Spa
Metallurgia Italiana | Year: 2014
The "secret" of an efficient Ring rolling production process is the ability of the ring rolling machine to maintain centered the ring, and drive the growt in height and diameter, avoiding non-round shapes and defects. In the real process, this work is done directly from the numerical control acting on the mandrel, cones and on the centering rolls (position and force), starting from a definition of the lamination curves, defined in the software by the operator. The machine try to respect this program, monitoring the shape of the ring, by some laser measuring system and load sensors, correcting the kinematic of the tools. In the last years several approaches have been used to simulate this process, always with the limit that the lamination curves must be inserted manually from the user and cannot change during the simulation. This paper is a summary of the work made by Muraro Spa, together with Transvalor S.A., the developer of FEM software Forge® and Enginsoft Spa, competence center on production process simulation. The aim of this work was to develop an interface able to read, in real-time during the calculation, the position of some virtual sensors (virtual laser measuring), pass informations like position, but also loads and others, to an external routine, able to calculate corrections of the kinematic of all the tools and write back these corrections in Forge. During the simulation, this approach allows to correct step-by-step the lamination curve. The logic in the simulation external black-box and in the program driving the piloting of the press is the same, so this guarantees that the results obtained with this new approach in the simulation are close to the real one. Next step of the work will be to extend the application of this interface to other models of special machines, but also to different kind of presses normally used to deform metallic (an non-metallic) materials.
Durin A.,CNRS Nantes Thermocinetique Lab |
Chenot J.-L.,TRANSVALOR S.A. |
Haudin J.-M.,MINES ParisTech |
Boyard N.,CNRS Nantes Thermocinetique Lab |
Bailleul J.-L.,CNRS Nantes Thermocinetique Lab
European Polymer Journal | Year: 2015
In this paper, a general numerical method to simulate polymer crystallization under various conditions is proposed. This method is first validated comparing its predictions with well-validated analytical models in infinite volumes. Then, it is compared to Billon et al. validated model for thin films, without or in presence of transcrystallinity on the films surfaces. It is also compared with Chenot et al. model for thin films, proposed in a conference in 2005 and never yet compared with other methods. Finally, it is also compared with an extension of this model for the transcrystalline case. These models are valid for general nucleation cases (not only sporadic or instantaneous), and can be used for any thermal conditions. All the numerical and analytical results are consistent, except in a case which is shown to be out of the validity domain of the transcrystalline case extension of Chenot et al. model. © 2015 Elsevier Ltd. All rights reserved.