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102 results on '"Département recherche et développements (R'

1. Utilisation du Dilatomètre Marchetti DMT pour l'étude de la stabilité des loess sur la LGV Nord : Application à l'évaluation du potentiel de liquéfaction

Author: Centre d'enseignement et de recherche en mécanique des sols (ENPC-CERMES) ; LCPC - Institut Navier - École des Ponts ParisTech (ENPC), Géotechnique ; Centre d'enseignement et de recherche en mécanique des sols (ENPC-CERMES) ; LCPC - Institut Navier - École des Ponts ParisTech (ENPC) - LCPC - Institut Navier - École des Ponts ParisTech (ENPC) - Laboratoire Navier (NAVIER) ; CNRS - École des Ponts ParisTech (ENPC) - IFSTTAR - Université Paris Est (UPE) - CNRS - IFSTTAR - Université Paris Est (UPE) - Department of geotechnical engineering (DGE) ; University of Tongji Shangaï - University of Tongji Shangaï - Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China ; affiliation inconnue - affiliation inconnue - State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China ; affiliation inconnue, Département recherche et développements (R&D - SNCF) ; SNCF, Département recherche et développements ; SNCF, Messen, Younès Hamza, Karam, Jean Paul, Cui, Yu-Jun, Terpereau, Jean Marc, Marchadier, Gilles, Centre d'enseignement et de recherche en mécanique des sols (ENPC-CERMES) ; LCPC - Institut Navier - École des Ponts ParisTech (ENPC), Géotechnique ; Centre d'enseignement et de recherche en mécanique des sols (ENPC-CERMES) ; LCPC - Institut Navier - École des Ponts ParisTech (ENPC) - LCPC - Institut Navier - École des Ponts ParisTech (ENPC) - Laboratoire Navier (NAVIER) ; CNRS - École des Ponts ParisTech (ENPC) - IFSTTAR - Université Paris Est (UPE) - CNRS - IFSTTAR - Université Paris Est (UPE) - Department of geotechnical engineering (DGE) ; University of Tongji Shangaï - University of Tongji Shangaï - Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China ; affiliation inconnue - affiliation inconnue - State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China ; affiliation inconnue, Département recherche et développements (R&D - SNCF) ; SNCF, Département recherche et développements ; SNCF, Messen, Younès Hamza, Karam, Jean Paul, Cui, Yu-Jun, Terpereau, Jean Marc, and Marchadier, Gilles
Abstract: Lors du passage du TGV sur la ligne Nord entre Paris et Lille, des cavités de tailles différentes ont été observées sur la plateforme et à proximité de la ligne. Certaines de ces cavités sont dues à l'effondrement de galeries souterraines de la première guerre mondiale. Les autres avaient des raisons méconnues à l'époque. Le sol en cause est le loess, très poreux sur certaines profondeurs (n=48%) et caractérisé par sa cimentation naturelle. Ce loess peut se liquéfier sous chargement cyclique lié au passage du train (Cui et al., 2003). La liquéfaction des sols est un phénomène qui est souvent observé lors des séismes. Elle n'a pas été jusqu'à présent observée sous des sollicitations ferroviaires. L'objectif est d'étudier le risque de liquéfaction du loess à partir de l'essai in-situ du Dilatomètre Marchetti DMT. Cet essai est connu pour sa sensibilité aux paramètres affectant la résistance à la liquéfaction des sols, entre autres, la cimentation. L'application de la "méthode simplifiée" à l'essai DMT à travers les formules existantes dans la littérature, a permis de démontrer le potentiel de liquéfaction du sol étudié. Cependant, ces corrélations ont été développées pour des sables saturés non cimentés, il serait donc intéressant d'établir des formules mieux adaptées au loess tout en tenant compte de la cimentation, afin d'obtenir un facteur de sécurité plus représentatif. A l'issue de cette étude, il est alors proposé de réaliser des essais triaxiaux cycliques qui permettront par la suite de déterminer la résistance à la liquéfaction du loess et de proposer une corrélation adéquate pour ce type de sol.

2. Procédé, dispositif et système de détection de défaut(s) d'un pantographe d'un véhicule en mouvement sur une voie ferrée

Author: Rivero , Alain, Paindavoine , Michel, Bruneau , Xavier, Département recherche et développements ( R&D - SNCF ), SNCF, Laboratoire d'Etude de l'Apprentissage et du Développement [Dijon] ( LEAD ), Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Globalsensing Technologies ( GST ), Département recherche et développements (R&D - SNCF), Laboratoire d'Etude de l'Apprentissage et du Développement [Dijon] (LEAD), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Globalsensing Technologies (GST), and université de Bourgogne, LEAD
Subjects: [SPI]Engineering Sciences [physics], [ INFO ] Computer Science [cs], [SPI] Engineering Sciences [physics], Système de détection de défaut, [ SPI ] Engineering Sciences [physics], [INFO]Computer Science [cs], [INFO] Computer Science [cs], Pantographe
Published: 2017

3. Optimization of a stabilized X-FEM formulation for frictional cracks

Author: Anthony Gravouil, Marie-Christine Baietto, T. M. L. Nguyen-Tajan, B. Trollé, Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] ( LaMCoS ), Institut National des Sciences Appliquées de Lyon ( INSA Lyon ), Université de Lyon-Institut National des Sciences Appliquées ( INSA ) -Université de Lyon-Institut National des Sciences Appliquées ( INSA ) -Centre National de la Recherche Scientifique ( CNRS ), Mécanique Multiéchelle pour les solides ( MIMESIS ), Université de Lyon-Institut National des Sciences Appliquées ( INSA ) -Université de Lyon-Institut National des Sciences Appliquées ( INSA ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut National des Sciences Appliquées de Lyon ( INSA Lyon ), Département recherche et développements ( R&D - SNCF ), SNCF, Mécanique Multiéchelle pour les solides (MIMESIS), Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] (LaMCoS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), and Département recherche et développements (R&D - SNCF)
Subjects: LBB condition, Optimization, Applied Mathematics, General Engineering, Geometry, X-FEM, Solver, [PHYS.MECA.SOLID]Physics [physics]/Mechanics [physics]/Mechanics of the solides [physics.class-ph], Computer Graphics and Computer-Aided Design, Finite element method, Nonlinear system, Operator (computer programming), Rate of convergence, [ SPI.MECA.SOLID ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of the solides [physics.class-ph], Applied mathematics, A priori and a posteriori, Polygon mesh, Boundary value problem, [SPI.MECA.SOLID]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of the solides [physics.class-ph], ComputingMilieux_MISCELLANEOUS, [ PHYS.MECA.SOLID ] Physics [physics]/Mechanics [physics]/Mechanics of the solides [physics.class-ph], Analysis, Frictional contact algorithm, Mathematics
Abstract: International audience; An efficient stabilized nonlinear LATIN solver dedicated to frictional cracks in the X-FEM framework is proposed. The performance of such a solver has already been emphasized in detail in a previous paper of Gravouil et al. [Stabilized global–local X-FEM for 3D non-planar frictional crack using relevant meshes, Int. J. Numer. Methods Eng. 88 (2011)1449–1475] Here, an optimization of the search direction of the LATIN solver is proposed. Intrinsic a priori formulas are proposed independently on the friction coefficient, the finite element mesh, the geometry and the boundary conditions. About one hundred thousand of calculations have been carried out in order to show the existence of a unique set of parameters ensuring the optimal convergence rate. The number of iterations required to reach the given level of accuracy is plotted versus two numerical parameters introduced, the search direction k and the stabilization operator . A considerable decrease in the number of iterations and thus in the computing time is obtained, an important condition to carry out with a maximum efficiency of 3D simulations.
Published: 2012
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4. Le rôle de l'expérience dans les contextes de changement du travail. Actes du séminaire Âges et Travail, mai 2010

Author: Volkoff , Serge, Delgoulet , Catherine, Meyer-Durat , Laurence, Chassaing , Karine, Gaudart , Corinne, Uzan-Chomat , Sylvette, Caroly , Sandrine, Alber , Alex, Guillemot , Danièle, Tirilly , Ghislaine, Beuchet , Cyril, Wolff , Loup, Zunigo , Xavier, Thévenet , Maurice, Cau-Bareille , Dominique, Duchet-Suchaux , Pascale, Centre de recherches sur l'expérience, l’âge et les populations au travail (Gis CREAPT), Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université (HESAM)-HESAM Université (HESAM), Laboratoire Adaptations Travail Individu (LATI - EA 4469), Université Paris Descartes - Paris 5 (UPD5), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA)), Laboratoire de l'intégration, du matériau au système (IMS), Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université Sciences et Technologies - Bordeaux 1, Université Paris Diderot - Paris 7 (UPD7), Pacte, Laboratoire de sciences sociales (PACTE), Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Joseph Fourier - Grenoble 1 (UJF)-Sciences Po Grenoble - Institut d'études politiques de Grenoble (IEPG)-Centre National de la Recherche Scientifique (CNRS), Centre d'études de l'emploi (CEE), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.)-Ministère du Travail, de l'Emploi et de la Santé, Laboratoire de sociologie quantitative (LSQ), Centre de Recherche en Économie et STatistique (CREST), Département recherche et développements (R&D - SNCF), SNCF, Centre de Recherche en Économie et Statistique (CREST), Ecole Nationale de la Statistique et de l'Analyse de l'Information [Bruz] (ENSAI)-École polytechnique (X)-École Nationale de la Statistique et de l'Administration Économique (ENSAE Paris)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL), Laboratoire interdisciplinaire de recherche en sciences de l'action (LIRSA), Chercheur indépendant, Créapt-CEE, Centre de recherches sur l'expérience, l’âge et les populations au travail (CREAPT), Laboratoire interdisciplinaire pour la sociologie économique (LISE), Centre National de la Recherche Scientifique (CNRS)-Conservatoire National des Arts et Métiers [CNAM] (CNAM)-Centre National de la Recherche Scientifique (CNRS)-Conservatoire National des Arts et Métiers [CNAM] (CNAM), Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Pacte, Laboratoire de sciences sociales, Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Joseph Fourier - Grenoble 1 (UJF)-Sciences Po Grenoble - Institut d'études politiques de Grenoble (IEPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Ecole Nationale de la Statistique et de l'Analyse de l'Information [Bruz] (ENSAI)-École polytechnique (X)-École Nationale de la Statistique et de l'Administration Économique (ENSAE ParisTech )-Centre National de la Recherche Scientifique (CNRS), CREAPT, Centre d'études de l'emploi ( CEE ), Ministère de l'Éducation nationale, de l’Enseignement supérieur et de la Recherche ( M.E.N.E.S.R. ) -Ministère du Travail, de l'Emploi et de la Santé-Ministère de l'Éducation nationale, de l’Enseignement supérieur et de la Recherche ( M.E.N.E.S.R. ) -Ministère du Travail, de l'Emploi et de la Santé, LATI, Laboratoire Adaptations Travail Individu ( LATI - EA 4469 ), Université Paris Descartes - Paris 5 ( UPD5 ) -Université Paris Descartes - Paris 5 ( UPD5 ), Université de Haute-Alsace (UHA) Mulhouse - Colmar ( Université de Haute-Alsace (UHA) ), COGNITIQUE, Laboratoire de l'intégration, du matériau au système ( IMS ), Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique ( CNRS ) -Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique ( CNRS ), Centre de recherches sur l'expérience, l’âge et les populations au travail ( CREAPT ), Laboratoire interdisciplinaire pour la sociologie économique ( LISE ), Conservatoire National des Arts et Métiers [CNAM] ( CNAM ) -Centre National de la Recherche Scientifique ( CNRS ) -Conservatoire National des Arts et Métiers [CNAM] ( CNAM ) -Centre National de la Recherche Scientifique ( CNRS ), Université Paris Diderot - Paris 7 ( UPD7 ), Université Pierre Mendès France - Grenoble 2 ( UPMF ) -Université Joseph Fourier - Grenoble 1 ( UJF ) -Sciences Po Grenoble - Institut d'études politiques de Grenoble ( IEPG ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ), Ministère de l'Éducation nationale, de l’Enseignement supérieur et de la Recherche ( M.E.N.E.S.R. ) -Ministère du Travail, de l'Emploi et de la Santé, Travailleurs et organisations, Laboratoire de sociologie quantitative ( LSQ ), Centre de Recherche en Économie et STatistique (CREST)-Centre de Recherche en Économie et STatistique (CREST), Département recherche et développements ( R&D - SNCF ), Centre de Recherche en Économie et Statistique ( CREST ), Ecole Nationale de la Statistique et de l'Analyse de l'Information [Bruz] ( ENSAI ) -École polytechnique ( X ) -École Nationale de la Statistique et de l'Administration Économique ( ENSAE ParisTech ), École normale supérieure - Paris ( ENS Paris ), Conservatoire National des Arts et Métiers - Paris ( CNAM Paris ), Conservatoire National des Arts et Métiers [CNAM] ( CNAM ), Institut d'études du travail de Lyon ( I.E.T.L ), Université Lumière - Lyon 2 ( UL2 ) -Université Lumière - Lyon 2 ( UL2 ), Prévention-santé-sécurité, and La poste
Subjects: [SHS.SOCIO]Humanities and Social Sciences/Sociology, savoirs professionnels, [SHS.GESTION]Humanities and Social Sciences/Business administration, [ SHS.SOCIO ] Humanities and Social Sciences/Sociology, organisation du travail, [ SHS.GESTION ] Humanities and Social Sciences/Business administration, [SHS.GENRE]Humanities and Social Sciences/Gender studies, [ SHS.GENRE ] Humanities and Social Sciences/Gender studies
Abstract: Ce rapport reprend in extenso les interventions et discussions du séminaire annuel du Créapt, édition 2010, dont le thème général était : "Le rôle de l'expérience dans les contextes de changement du travail". Comme à chacune de ses sessions, ce séminaire rassemble des chercheurs de différentes disciplines, des praticiens, des étudiants autour d'une dizaine d'exposés-débats destinés à approfondir un aspect des relations entre l'âge, l'expérience, la santé, et le travail. Le thème choisi pour l'édition 2010 avait sa raison d'être au regard du débat social, à cause d'une confrontation délicate entre la proportion croissante de salariés expérimentés et la volonté affirmée de réorganiser sans cesse les entreprises. Cette question sociale rejoint une question scientifique, celle d'une compréhension des modes d'élaboration de l'expérience au travail, et des ressources qu'elle apporte, avec une difficulté à saisir si, et dans quelle mesure, les transformations dans les systèmes de production favorisent ou restreignent cet apport de ressources. Le cadre théorique de la réflexion est donné par un exposé introductif, qui reprend un ensemble d'acceptions de l'expérience d'une part, des changements d'autre part, et présente des modèles d'analyse qui correspondent à ces différentes acceptions, avant d'expliquer, à partir d'études spécifiques, comment le lien expérience/changement a pu être abordé dans plusieurs recherches, menées sur des terrains très divers.
Published: 2013

5. A benchmark for particle shape dependence

Author: Gaël Combe, Cécile Nouguier-Lehon, Émilien Azéma, Krzysztof Szarf, Baptiste Saint-Cyr, Marie Chaze, Farhang Radjaï, Pascal Villard, Jean-Yves Delenne, Vincent Richefeu, Philippe Sornay, Charles Voivret, null CEGEO Group, Laboratoire sols, solides, structures - risques [Grenoble] (3SR), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), GéoMécanique, Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS), Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Laboratoire des Combustibles Uranium (LCU), Service d'Analyses, d'Elaboration, d'Expérientations et d'Examens des combustibles (SA3E), Département d'Etudes des Combustibles (DEC), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département recherche et développements (R&D - SNCF), SNCF, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Laboratoire sols, solides, structures - risques [Grenoble] ( 3S-R ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut National Polytechnique de Grenoble ( INPG ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ), Laboratoire de Tribologie et Dynamique des Systèmes ( LTDS ), École Centrale de Lyon ( ECL ), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État ( ENTPE ) -Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique ( CNRS ), Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Ingénierie des Agro-polymères et Technologies Émergentes ( IATE ), Centre de Coopération Internationale en Recherche Agronomique pour le Développement ( CIRAD ) -Institut National de la Recherche Agronomique ( INRA ) -Université Montpellier 2 - Sciences et Techniques ( UM2 ) -Centre international d'études supérieures en sciences agronomiques ( Montpellier SupAgro ) -Université de Montpellier ( UM ) -Institut national d’études supérieures agronomiques de Montpellier ( Montpellier SupAgro ), Laboratoire des Combustibles Uranium ( LCU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), Département recherche et développements ( R&D - SNCF ), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne (ENISE)-Centre National de la Recherche Scientifique (CNRS), and Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)
Subjects: Materials science, 02 engineering and technology, [SPI.MECA.MSMECA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Materials and structures in mechanics [physics.class-ph], Atomic packing factor, Granular material, 01 natural sciences, Shape parameter, Contact force, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], Molecular dynamics, Shape Dependence, 0103 physical sciences, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [ PHYS.MECA.MSMECA ] Physics [physics]/Mechanics [physics]/Materials and structures in mechanics [physics.class-ph], 010308 nuclear & particles physics, Shear Test, Numerical analysis, Random close pack, Molecular Dynamic, Mechanics, [PHYS.MECA.MSMECA]Physics [physics]/Mechanics [physics]/Materials and structures in mechanics [physics.class-ph], 021001 nanoscience & nanotechnology, [ SPI.MECA.MSMECA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Materials and structures in mechanics [physics.class-ph], Polygones, Contact Dynamic, PACS: 45.70.-n, 81.05.Rm, 61.43.Hv, Classical mechanics, [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], Clumps, Direct shear test, 0210 nano-technology, Granular Media
Abstract: International audience; Particle shape is a major parameter for the space-filling and strength properties of granular materials. For a systematic investigation of shape effect, a numerical benchmark test was set up within a collaborative group using different numerical methods and particles of various shape characteristics such as elongation, angularity and nonconvexity. Extensive 2D shear simulations were performed in this framework and the shear strength and packing fraction were compared for different shapes.We show that the results may be analyzed in terms of a low-order shape parameter h describing the degree of distortion from a perfectly circular shape. In particular, the shear strength is an increasing function of h with nearly the same trend for all shapes, the differences being of second order compared to h. We also observe a nontrivial behavior of packing fraction which, for all our simulated shapes, increases with h from the random close packing fraction for disks, reaches a peak considerably higher than that for disks, and subsequently declines as h is further increased. Finally, the analysis of contact forces for the same value of h leads to very similar statistics regardless of our specific particle shapes.
Published: 2013
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6. Comparison of dynamic models for a DC railway electrical network including an AC/DC bi-directional power station

Author: N’guessan Kouassi, Christophe Saudemont, Tony Letrouve, Bruno Francois, Nicolas Navarro, Khaled Almaksour, Youssef Krim, Benoit Robyns, Lionel Taunay, Laboratoire d’Électrotechnique et d’Électronique de Puissance - ULR 2697 (L2EP), Centrale Lille-Université de Lille-Arts et Métiers Sciences et Technologies, HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Université Félix Houphouët-Boigny (UFHB), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL), Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Centrale Lille, L2EP - Équipe Réseaux, Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Arts et Métiers Sciences et Technologies, Département recherche et développements (R&D - SNCF), and SNCF
Subjects: Numerical Analysis, General Computer Science, Power station, Computer science, Applied Mathematics, [SPI.NRJ]Engineering Sciences [physics]/Electric power, Automotive engineering, Theoretical Computer Science, law.invention, Regenerative brake, Real-time simulation, law, Modeling and Simulation, Electrical network, Inverter, Train, Electric power, ComputingMilieux_MISCELLANEOUS, Efficient energy use
Abstract: To face environmental issues, SNCF, the French railway, has chosen to improve the energy efficiency of its electrical power system by investigating solutions for regenerative braking. With the contribution of Railenium, a research and test center in railway activities, they aim to recover the braking energy by setting up a reversible inverter in the DC substation ”Massena”. The issue is to test, implement and compare various control solutions to increase the energy efficiency with minimum impacts on the railway operation. In this paper, a simulation model for studying a reversible power substation is addressed by considering AC and DC equivalent electrical sources. The proposed model provides a reliable tool for analyzing the behavior of the railway electrical network during specially braking mode. In order to validate this model, its simulation results are compared with the ones obtained from Esmeralda, the SNCF professional software. A first configuration is led without the inverter and gives certified Esmeralda results and validates the proposed model despite some gaps in powers and voltages due to differences in input data and models. A second comparison with inverter is presented to highlight the main difference between the proposed model and Esmeralda. In addition, laboratory experimental activities are put forward to investigate the proposed model by using power-hardware-in-the-loop simulations. Finally, a simulation test under MATLAB software with fifty train’s traffic is presented to estimate the energy saving thanks to the installed inverter. For this latter case study, the system sent back to the national AC grid around 6.9% of the total energy consumed by all trains.
Published: 2021
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7. Particle shape dependence in 2D granular media

Author: Krzysztof Szarf, Emilien Azéma, C. Nouguier-Lehon, Vincent Richefeu, Jean-Yves Delenne, Pascal Villard, Charles Voivret, Gaël Combe, Philippe Sornay, B. Saint-Cyr, Cegeo, Farhang Radjai, Marie Chaze, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire sols, solides, structures - risques [Grenoble] ( 3S-R ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut National Polytechnique de Grenoble ( INPG ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ), Département recherche et développements ( R&D - SNCF ), SNCF, École Centrale de Lyon ( ECL ), Université de Lyon, Laboratoire Sols, Solides, Structures ( 3S ), Université Joseph Fourier - Grenoble 1 ( UJF ), Laboratoire des Combustibles Uranium ( LCU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), Laboratoire de Tribologie et Dynamique des Systèmes ( LTDS-ENSMSE ), École des Mines de Saint-Étienne ( Mines Saint-Étienne MSE ), Institut Mines-Télécom [Paris]-Institut Mines-Télécom [Paris]-École Centrale de Lyon ( ECL ), Université de Lyon-Université de Lyon-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique ( CNRS ), Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire sols, solides, structures - risques [Grenoble] (3SR), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), École Centrale de Lyon (ECL), Laboratoire Sols, Solides, Structures (3S), Université Joseph Fourier - Grenoble 1 (UJF), Laboratoire des Combustibles Uranium (LCU), Service d'Analyses, d'Elaboration, d'Expérientations et d'Examens des combustibles (SA3E), Département d'Etudes des Combustibles (DEC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Société Nationale des Chemins de Fer Français (SNCF), Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Université de Lyon (COMUE), French government, Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), and Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne (ENISE)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, ASSEMBLIES, FOS: Physical sciences, General Physics and Astronomy, ELLIPSOIDS, Condensed Matter - Soft Condensed Matter, Granular material, Atomic packing factor, 01 natural sciences, Convexity, Shape parameter, 010305 fluids & plasmas, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [SPI]Engineering Sciences [physics], Distortion, [SDV.IDA]Life Sciences [q-bio]/Food engineering, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], 0103 physical sciences, particle shape, granular matter, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, shear strength, 010306 general physics, packing fraction, Random close pack, friction mobilization, Mechanics, PACKINGS, Condensed Matter::Soft Condensed Matter, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Soft Condensed Matter (cond-mat.soft), Particle, Shear strength (discontinuity)
Abstract: Particle shape is a key to the space-filling and strength properties of granular matter. We consider a shape parameter $\eta$ describing the degree of distortion from a perfectly spherical shape. Encompassing most specific shape characteristics such as elongation, angularity and nonconvexity, $\eta$ is a low-order but generic parameter that we used in a numerical benchmark test for a systematic investigation of shape-dependence in sheared granular packings composed of particles of different shapes. We find that the shear strength is an increasing function of $\eta$ with nearly the same trend for all shapes, the differences appearing thus to be of second order compared to $\eta$. We also observe a nontrivial behavior of packing fraction which, for all our simulated shapes, increases with $\eta$ from the random close packing fraction for disks, reaches a peak considerably higher than that for disks, and subsequently declines as $\eta$ is further increased. These findings suggest that a low-order description of particle shape accounts for the principal trends of packing fraction and shear strength. Hence, the effect of second-order shape parameters may be investigated by considering different shapes at the same level of $\eta$., Comment: 5 pages, 8 figures
Published: 2012
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8. Stability, deformation and variability of granular fills composed of polyhedral particles

Author: Farhang Radjai, Gilles Saussine, Pierre Breul, Juan Carlos Quezada, Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Département recherche et développements ( R&D - SNCF ), SNCF, Laboratoire de micromécanique et intégrité des structures ( MIST ), Institut de Radioprotection et de Sûreté Nucléaire ( IRSN ) -Centre National de la Recherche Scientifique ( CNRS ), Physique et Mécanique des Milieux Granulaires ( PMMG ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), Laboratoire de micromécanique et intégrité des structures (MIST), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Centre National de la Recherche Scientifique (CNRS), Physique et Mécanique des Milieux Granulaires (PMMG), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: polyhedral particles, Mechanical equilibrium, Materials science, fluctuations, Strong interaction, 0211 other engineering and technologies, 02 engineering and technology, Deformation (meteorology), Granular material, 01 natural sciences, law.invention, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], law, 0103 physical sciences, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], granular matter, Contact dynamics, shear strength, 010306 general physics, 021101 geological & geomatics engineering, Mechanics, Aspect ratio (image), Classical mechanics, Coulomb friction, transient deformation, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], contact dynamics, Particle, Shear strength (discontinuity)
Abstract: International audience; By means of extensive contact dynamics simulations, we investigate the mechanical equilibrium and deformation of a granular material composed of irregular polyhedral particles confined between two horizontal frictional planes. We show that, as a consequence of mobilized wall-particle friction force at the top and bottom boundaries, the transient deformation induced by a constant vertical load is controlled by the aspect ratio (thickness over width) of the packing as well as the stress ratio. The transient deformation declines considerably for increasingly smaller aspect ratios and grows with the stress ratio. From the simulation data for a large number of independent configurations, we find that sample-to-sample fluctuations of the deformation have a broad distribution and they scale with the average deformation. We also analyze the evolution of particle connectivity during settlement and with the applied force. The face-face and edge-face contacts between polyhedral particles concentrate strong force chains with a growing proportion as a function of the applied force.
Published: 2012
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9. Décomposition de Domaine dans la simulation par Éléments Discrets en utilisant le calcul parallèle à mémoire partagée pour des applications ferroviaires

Author: Thi Minh Phuong Hoang, Gilles Saussine, David Dureisseix, Pierre Alart, Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Département recherche et développements ( R&D - SNCF ), SNCF, Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] ( LaMCoS ), Institut National des Sciences Appliquées de Lyon ( INSA Lyon ), Université de Lyon-Institut National des Sciences Appliquées ( INSA ) -Université de Lyon-Institut National des Sciences Appliquées ( INSA ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] (LaMCoS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [ SPI.MECA ] Engineering Sciences [physics]/Mechanics [physics.med-ph], [SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph]
Abstract: National audience; See http://hal.archives-ouvertes.fr/docs/00/59/27/28/ANNEX/r_FM15Z0J4.pdf
Published: 2011

10. Particle assembling methods

Author: Voivret , Charles, Radjai , Farhang, Delenne , Jean-Yves, Département recherche et développements ( R&D - SNCF ), SNCF, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), F. Radjai et F. Dubois, Département recherche et développements (R&D - SNCF), Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], Condensed Matter::Soft Condensed Matter, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], granular matter
Abstract: International audience; The rheology of granular materials is largely dominated by geometrical constraints arising from steric exclusions and involving particle shapes and size distributions. This prevailing role of geometry permits one to simplify sometimes the dynamics in favor of a better description of the geometry or/and higher numerical efficiency. For example, a dense granular packing may be efficiently constructed by replacing the equations of dynamics by simple displacement rules satisfying the geometrical constraints. Such purely geometrical procedures can be much simpler and numerically faster than more realistic procedures employed in dynamic methods and quasistatic methods. The issue of the assembling methods is to construct configurations of particles as close as possible to a state of mechanical equilibrium with built-in packing properties. This can be, for example, a target packing fraction for a given particle size distribution. In the same way, the average connectivity of the particles (coordination number) and the anisotropy of the contact network are basic geometrical properties that control the mechanical response of a packing and may be built into a packing by an appropriate method. The homogeneity of the particle assembly in terms of packing fraction and connectivity is another important property which depends on the assembling rules. In this chapter, several basic assembling methods by simple geometrical rules will be introduced. As there is a close link between the particle size distribution (PSD) and texture of a granular packing, \index{particle size distribution} we also present a method for the generation of PSD and we discuss in detail their statistical representativity and influence on the packing properties.
Published: 2011

11. Rheology of granular materials composed of nonconvex particles

Author: Charles Voivret, Jean-Yves Delenne, Baptiste Saint-Cyr, Philippe Sornay, Farhang Radjai, Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Combustibles Uranium (LCU), Service d'Analyses, d'Elaboration, d'Expérientations et d'Examens des combustibles (SA3E), Département d'Etudes des Combustibles (DEC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Département recherche et développements (R&D - SNCF), SNCF, Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Ingénierie des Agro-polymères et Technologies Émergentes ( IATE ), Centre de Coopération Internationale en Recherche Agronomique pour le Développement ( CIRAD ) -Institut National de la Recherche Agronomique ( INRA ) -Université Montpellier 2 - Sciences et Techniques ( UM2 ) -Centre international d'études supérieures en sciences agronomiques ( Montpellier SupAgro ) -Université de Montpellier ( UM ) -Institut national d’études supérieures agronomiques de Montpellier ( Montpellier SupAgro ), Département recherche et développements ( R&D - SNCF ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire des Combustibles Uranium ( LCU ), and Commissariat à l'énergie atomique et aux énergies alternatives ( CEA )
Subjects: Materials science, Isotropy, Mechanics, Granular material, Atomic packing factor, 01 natural sciences, 010305 fluids & plasmas, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], Rheology, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], 0103 physical sciences, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Shear strength, Particle, Contact dynamics, 010306 general physics, Anisotropy, ComputingMilieux_MISCELLANEOUS
Abstract: International audience; By means of contact dynamics simulations, we investigate the shear strength and internal structure of granular materials composed of two-dimensional nonconvex aggregates. We find that the packing fraction first grows as the nonconvexity is increased but declines at higher nonconvexity. This unmonotonic dependence reflects the competing effects of pore size reduction between convex borders of aggregates and gain in porosity at the nonconvex borders that are captured in a simple model fitting nicely the simulation data both in the isotropic and sheared packings. On the other hand, the internal angle of friction increases linearly with nonconvexity and saturates to a value independent of nonconvexity. We show that fabric anisotropy, force anisotropy, and friction mobilization, all enhanced by multiple contacts between aggregates, govern the observed increase of shear strength and its saturation with increasing nonconvexity. The main effect of interlocking is to dislocate frictional dissipation from the locked double and triple contacts between aggregates to the simple contacts between clusters of aggregates. This self-organization of particle motions allows the packing to keep a constant shear strength at high nonconvexity.
Published: 2011
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12. Periodic boundary conditions

Author: Radjai , Farhang, Voivret , Charles, Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), SNCF, F. Radjai et F. Dubois, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), and Département recherche et développements ( R&D - SNCF )
Subjects: [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], contact dynamics, granular matter, discrete element method, periodic boundary conditions
Abstract: International audience; In this chapter, we present a method for the prescription of periodic boundary conditions in DEM simulations of granular materials. This method is similar in practice to that of Parrinello and Rahman, but since the particle interactions are dissipative in a granular system, the equations of motion for collective dynamic variables can not be based on a Hamiltonian. We consider in detail the particular kinematics of periodic systems, the equations of dynamics and time-stepping schemes for MD-DEM and CD-DEM.
Published: 2011

13. Force Transmission in Cohesive Granular Media

Author: Radjai, Farhang, Topin, Vincent, Richefeu, Vincent, Voivret, Charles, Delenne, Jean-Yves, Azéma, Emilien, El Youssoufi, Moulay Saïd, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de micromécanique et intégrité des structures ( MIST ), Institut de Radioprotection et de Sûreté Nucléaire ( IRSN ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire sols, solides, structures - risques [Grenoble] ( 3S-R ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut National Polytechnique de Grenoble ( INPG ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ), Département recherche et développements ( R&D - SNCF ), SNCF, J. D. Goddard, J. T. Jenkins et P. Giovine, Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de micromécanique et intégrité des structures (MIST), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire sols, solides, structures - risques [Grenoble] (3SR), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), and Département recherche et développements (R&D - SNCF)
Subjects: [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], Condensed Matter::Soft Condensed Matter, granular materials, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], force transmission
Abstract: We use numerical simulations to investigate force and stress transmission in cohesive granular media covering a wide class of materials encountered in nature and industrial processing. The cohesion results either from capillary bridges between particles or from the presence of a solid binding matrix filling fully or partially the interstitial space. The liquid bonding is treated by implementing a capillary force law within a debonding distance between particles and simulated by the discrete element method. The solid binding matrix is treated by means of the Lattice Element Method (LEM) based on a lattice-type discretization of the particles and matrix. Our data indicate that the exponential fall-off of strong compressive forces is a generic feature of both cohesive and noncohesive granular media both for liquid and solid bonding. The tensile forces exhibit a similar decreasing exponential distribution, suggesting that this form basically reflects granular disorder. This is consistent with the finding that not only the contact forces but also the stress components in the bulk of the particles and matrix, accessible from LEM simulations in the case of solid bonding, show an exponential fall-off. We also find that the distribution of weak compressive forces is sensitive to packing anisotropy, particle shape and particle size distribution. In the case of wet packings, we analyze the self-equilibrated forces induced by liquid bonds and show that the positive and negative particle pressures form a bi-percolating structure.
Published: 2010

14. Conditions aux limites périodiques

Author: Radjai , Farhang, Voivret , Charles, Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), SNCF, F. Radjai et F. Dubois, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), and Département recherche et développements ( R&D - SNCF )
Subjects: [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], modélisation discrète, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], matériaux granulaires, conditions aux limites périodiques, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], dynamique moléculaire, dynamique des contacts
Abstract: National audience; 1.1.Introduction.................................. 11 1.2.Lacinématique ................................ 13 1.2.1.Périodicitéenposition......................... 13 1.2.2.Coordonnéesréduites ......................... 14 1.2.3.Périodicitéenvitesse.......................... 15 1.2.4.Tenseurmétrique............................ 16 1.2.5.Transformationsmodulaires...................... 17 1.3.Ladynamique................................. 18 1.3.1.Degrésdelibertécollectifs ...................... 18 1.3.2.Degrésdelibertédesparticules.................... 20 1.4.Schémasd'intégration ............................ 22 1.4.1.DynamiquedesContacts ....................... 22 1.4.2.DynamiqueMoléculaire........................ 24 1.4.3.Précautionsdemiseenœuvre..................... 27 1.5.Conclusion .................................. 28 1.6.Bibliographie ................................. 29
Published: 2010

15. Force transmission in highly polydisperse granular media

Author: Voivret, Charles, Delenne, Jean-Yves, Radjai, Farhang, El Youssoufi, Moulay Saïd, Département recherche et développements (R&D - SNCF), SNCF, Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Physique et Mécanique des Milieux Granulaires (PMMG), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements ( R&D - SNCF ), Ingénierie des Agro-polymères et Technologies Émergentes ( IATE ), Centre de Coopération Internationale en Recherche Agronomique pour le Développement ( CIRAD ) -Université de Montpellier ( UM ) -Université Montpellier 2 - Sciences et Techniques ( UM2 ) -Institut national d’études supérieures agronomiques de Montpellier ( Montpellier SupAgro ) -Institut National de la Recherche Agronomique ( INRA ) -Centre international d'études supérieures en sciences agronomiques ( Montpellier SupAgro ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Physique et Mécanique des Milieux Granulaires ( PMMG ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)
Subjects: [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2009

16. Effect of shape nonconvexity on the shear strength of granular media

Author: Saint-Cyr, Baptiste, Voivret, Charles, Delenne, Jean-Yves, Radjai, Farhang, Sornay, Philippe, Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), SNCF, Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Combustibles Uranium (LCU), Service d'Analyses, d'Elaboration, d'Expérientations et d'Examens des combustibles (SA3E), Département d'Etudes des Combustibles (DEC), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Département recherche et développements ( R&D - SNCF ), Ingénierie des Agro-polymères et Technologies Émergentes ( IATE ), Centre de Coopération Internationale en Recherche Agronomique pour le Développement ( CIRAD ) -Université de Montpellier ( UM ) -Université Montpellier 2 - Sciences et Techniques ( UM2 ) -Institut national d’études supérieures agronomiques de Montpellier ( Montpellier SupAgro ) -Institut National de la Recherche Agronomique ( INRA ) -Centre international d'études supérieures en sciences agronomiques ( Montpellier SupAgro ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire des Combustibles Uranium ( LCU ), and Commissariat à l'énergie atomique et aux énergies alternatives ( CEA )
Subjects: [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2009

17. Quasistatic rheology, force transmission and fabric properties of a packing of irregular polyhedral particles

Author: Farhang Radjai, Emilien Azéma, Gilles Saussine, Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Physique et Mécanique des Milieux Granulaires ( PMMG ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Département recherche et développements ( R&D - SNCF ), SNCF, LMGC SNCF, Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Physique et Mécanique des Milieux Granulaires (PMMG), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Département recherche et développements (R&D - SNCF)
Subjects: polyhedral particles, Materials science, granular materials, 0211 other engineering and technologies, FOS: Physical sciences, Geometry, 02 engineering and technology, Physics - Classical Physics, Granular material, Atomic packing factor, 01 natural sciences, Contact force, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], 0103 physical sciences, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Shear stress, contact dynamics method, General Materials Science, shear strength, Force chain, 010306 general physics, Anisotropy, Instrumentation, 021101 geological & geomatics engineering, Shearing (physics), Classical Physics (physics.class-ph), force chain, Condensed Matter::Soft Condensed Matter, Sphere packing, Mechanics of Materials, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], granular fabric
Abstract: International audience; By means of contact dynamics simulations, we investigate a dense packing composed of polyhedral particles under quasistatic shearing. The effect of particle shape is analyzed by comparing the polyhedra packing with a packing of similar characteristics except for the spherical shape of the particles. The polyhedra packing shows higher shear stress and dilatancy but similar stress-dilatancy relation compared to the sphere packing. A harmonic approximation of granular fabric is presented in terms of branch vectors (connecting particle centers) and contact force components along and perpendicular to the branch vectors. It is found that the origin of enhanced shear strength of the polyhedra packing lies in its higher force anisotropy with respect to the sphere packing which has a higher fabric anisotropy. Various contact types (face-vertex, face-face, etc) contribute differently to force transmission and fabric anisotropy. In particular, most face-face contacts belong to strong force chains along the major principal stress direction whereas vertex-face contacts are correlated with weak forces and oriented on average along the minor principal stress direction in steady shearing.
Published: 2009
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18. Multiscale Force Networks in Highly Polydisperse Granular Media

Author: Jean-Yves Delenne, Farhang Radjai, M. S. El Youssoufi, Charles Voivret, Département recherche et développements ( R&D - SNCF ), SNCF, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Département recherche et développements (R&D - SNCF), Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, fabric anisotropy, Strong interaction, 0211 other engineering and technologies, General Physics and Astronomy, 02 engineering and technology, Weak interaction, Granular material, 01 natural sciences, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], 0103 physical sciences, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Cohesion (geology), granular matter, force distribution, Contact dynamics, shear strength, 010306 general physics, Anisotropy, 021101 geological & geomatics engineering, polydspersity, Mechanics, Simple shear, Condensed Matter::Soft Condensed Matter, Classical mechanics, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Particle size, contact anisotropy
Abstract: International audience; We investigate highly polydisperse packings subjected to simple shear by contact dynamics simula- tions. A major unsolved issue is how granular texture and force chains depend on the size polydispersity and how far they influence the shear strength. The numerical treatment was made possible by ensuring the statistical representativity of particle size classes. An unexpected finding is that the internal friction angle is independent of polydispersity. We show that this behavior is related to two mechanisms underlying the stability of force chains: (i) The class of largest particles captures strong force chains, and (ii) these chains are equilibrated by weak forces carried by increasingly smaller particles as the size span broadens. In the presence of adhesion between particles, the Coulomb cohesion increases with size polydispersity as a result of enhanced force anisotropy.
Published: 2009
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19. Vibrational dynamics of 3D granular media composed with polyhedral grains

Author: Azéma , Emilien, Radjai , Farhang, Peyroux , Robert, Dubois , Frédéric, Saussine , Gilles, Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Réseaux, Moyens Informatiques, Calcul Scientifique (Remics), Département recherche et développements (R&D - SNCF), SNCF, Projet Ecos Nord, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Réseaux, Moyens Informatiques, Calcul Scientifique ( Remics ), and Département recherche et développements ( R&D - SNCF )
Subjects: vibrations, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], Contact Dynamic, granular, polyedric particles, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph]
Abstract: National audience; By means of tree-dimensional contact dynamics simulations, we analyze the vibrational dynamics of a confined granular layer in response to harmonic forcing. The sample is composed of polyedric grains with a shape derived from digitalized ballast. The system involves a jammed state separating passive (loading) and active (unloading) states. We show that an approximate expression of the packing resistance force as a function of the displacement of the free retaining wall from the jamming position provides a good description of the dynamics. We study in detail the scaling of displacements and velocities with loading parameters. In particular, we find that, for a wide range of frequencies, the data collapse by scaling the displacements with the inverse square of frequency, the inverse of the force amplitude and the square of gravity. We show that the mean compaction rate increases linearly with frequency up to a characteristic frequency of 10 Hz and then it declines in inverse proportion to frequency.
Published: 2008

20. Dinámica vibracional de un medio granular 3D compuesto de partículas poliédricas

Author: Emilien Azéma, Farhang Radjai, Robert Peyroux, Frédéric Dubois, Gilles Saussine, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Réseaux, Moyens Informatiques, Calcul Scientifique ( Remics ), Département recherche et développements ( R&D - SNCF ), SNCF, Projet Ecos Nord, Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Réseaux, Moyens Informatiques, Calcul Scientifique (Remics), and Département recherche et développements (R&D - SNCF)
Subjects: [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], vibrations, Contact Dynamic, granular, polyedric particles, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph]
Abstract: National audience; By means of tree-dimensional contact dynamics simulations, we analyze the vibrational dynamics of a confined granular layer in response to harmonic forcing. The sample is composed of polyedric grains with a shape derived from digitalized ballast. The system involves a jammed state separating passive (loading) and active (unloading) states. We show that an approximate expression of the packing resistance force as a function of the displacement of the free retaining wall from the jamming position provides a good description of the dynamics. We study in detail the scaling of displacements and velocities with loading parameters. In particular, we find that, for a wide range of frequencies, the data collapse by scaling the displacements with the inverse square of frequency, the inverse of the force amplitude and the square of gravity. We show that the mean compaction rate increases linearly with frequency up to a characteristic frequency of 10 Hz and then it declines in inverse proportion to frequency.
Published: 2008

21. Short-time dynamics of a packing of polyhedral grains under horizontal vibrations

Author: Gilles Saussine, Robert Peyroux, Vincent Richefeu, Emilien Azéma, Farhang Radjai, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), ThermoMécanique des Matériaux ( ThM2 ), Département recherche et développements ( R&D - SNCF ), SNCF, Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), ThermoMécanique des Matériaux (ThM2), and Département recherche et développements (R&D - SNCF)
Subjects: Models, Molecular, Time Factors, Materials science, Polymers, Biophysics, FOS: Physical sciences, Physics - Classical Physics, Granular material, Vibration, 01 natural sciences, 010305 fluids & plasmas, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], 0103 physical sciences, horizontal vibration, Computer Simulation, General Materials Science, Contact dynamics, compaction, Particle Size, polyhedral, 010306 general physics, Scaling, Anharmonicity, Classical Physics (physics.class-ph), Surfaces and Interfaces, General Chemistry, Mechanics, Particle displacement, Amplitude, Classical mechanics, granular, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], dynamique, Nanoparticles, Particle, ratcheting, Biotechnology
Abstract: International audience; We analyze the dynamics of a 3D granular packing composed of particles of irregular polyhedral shape confined inside a rectangular box with a retaining wall sub jected to horizontal harmonic forcing. The simulations are performed by means of the contact dynamics method for a broad set of loading parameters. We explore the vibrational dynamics of the packing, the evolution of solid fraction and the scaling of dy- namics with the loading parameters. We show that the motion of the retaining wall is strongly anharmonic as a result of jamming and grain rearrangements. It is found that the mean particle displacement scales with inverse square of frequency, the inverse of the force amplitude and the square of gravity. The short- time compaction rate grows in proportion to frequency up to a characteristic frequency, corresponding to collective particle rearrangements between equilibrium states, and then it declines in inverse proportion to frequency.
Published: 2008
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22. Dynamique d'un milieu granulaire soumis à des vibrations horizontales - Simulations numériques 3D

Author: Azéma, Emilien, Radjai, Farhang, Peyroux, Robert, Saussine, Gilles, Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Physique et Mécanique des Milieux Granulaires (PMMG), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), SNCF, Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Physique et Mécanique des Milieux Granulaires ( PMMG ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), and Département recherche et développements ( R&D - SNCF )
Subjects: [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], dynamic, granular, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], vibrational, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], polyhedric
Abstract: The tamping operation on railway ballast is an example where the vibrations are used to restore the initial geometry of the track distorted as a result of ballast settlement. By means of tree-dimensional contact dynamics simulations, we analyze the vibrational dynamics of a confined granular layer in response to harmonic forcing. The sample is composed of polyedric grains with a shape derived from digitalized ballast. The system involves a jammed state separating passive (loading) and active (unloading) states. We show that an approximate expression of the packing resistance force as a function of the displacement of the free retaining wall from the jamming position provides a good description of the dynamics. We study in detail the scaling of displacements and velocities with loading parameters. In particular, we find that, for a wide range of frequencies, the data collapse by scaling the displacements with the inverse square of frequency, the inverse of the force amplitude and the square of gravity. We show that the mean compaction rate increases linearly with frequency up to a characteristic frequency of 10 Hz and then it declines in inverse proportion to frequency.
Published: 2007

23. Space-filling properties of polydisperse granular media

Author: Charles Voivret, Farhang Radjai, Jean-Yves Delenne, M. S. El Youssoufi, Département recherche et développements (R&D - SNCF), SNCF, Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Physique et Mécanique des Milieux Granulaires (PMMG), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements ( R&D - SNCF ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Ingénierie des Agro-polymères et Technologies Émergentes ( IATE ), Centre de Coopération Internationale en Recherche Agronomique pour le Développement ( CIRAD ) -Institut National de la Recherche Agronomique ( INRA ) -Université Montpellier 2 - Sciences et Techniques ( UM2 ) -Centre international d'études supérieures en sciences agronomiques ( Montpellier SupAgro ) -Université de Montpellier ( UM ) -Institut national d’études supérieures agronomiques de Montpellier ( Montpellier SupAgro ), Physique et Mécanique des Milieux Granulaires ( PMMG ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)
Subjects: Uniform distribution (continuous), Materials science, Particle number, Dispersity, Geometry, Granular material, 01 natural sciences, 010305 fluids & plasmas, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], 0103 physical sciences, Particle, Particle size, Statistical physics, 010306 general physics, Anisotropy, Porous medium, ComputingMilieux_MISCELLANEOUS
Abstract: We present a systematic investigation of the morphology and space-filling properties of polydisperse densely packed granular media in two dimensions. A numerical procedure is introduced to generate collections of circular particles with size distributions of variable shape and span constrained by explicit criteria of statistical representativity. We characterize the domain of statistically accessible distribution parameters for a bounded number of particles. This particle generation procedure is used with two different deposition protocols in order to build large close-packed samples of prescribed polydispersity. We find that the solid fraction is a strongly nonlinear function of the size span, and the highest levels of solid fraction occur for the uniform distribution by volume fractions. As the span is increased, a transition occurs from a regime of topological disorder where the packing properties are governed by particle connectivity to a regime of metric disorder where pore-filling small particles prevail. The polydispersity manifests itself in the first regime through the variability of local coordination numbers. We observe a continuous decrease of the number of particles with four contacts and the growth of two populations of particles with three and five contacts. In the second regime, radial distribution functions show that the material is homogeneous beyond only a few average particle diameters. We also show that the packing orientational order is linked with fabric anisotropy and it declines with size span.
Published: 2007
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24. Transmission des forces dans un milieu compos\'e de grains non sph\'eriques

Author: Azéma, Emilien, Radjai, Farhang, Peyroux, Robert, Saussine, Gilles, Physique et Mécanique des Milieux Granulaires ( PMMG ), Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Département recherche et développements ( R&D - SNCF ), SNCF, Physique et Mécanique des Milieux Granulaires (PMMG), Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Département recherche et développements (R&D - SNCF)
Subjects: [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], Condensed Matter::Soft Condensed Matter, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Physics - Classical Physics
Abstract: We perform a detailed analysis of the contact force network in a dense confined packing of pentagonal particles simulated by means of the contact dynamics method. The effect of particle shape is evidenced by comparing the data from pentagon packing and from a packing with identical characteristics except for the circular shape of the particles. A counterintuitive finding of this work is that, under steady shearing, the pentagon packing develops a lower structural anisotropy than the disk packing. We show that this weakness is compensated by a higher force anisotropy, leading to enhanced shear strength of the pentagon packing. We revisit ''strong" and ''weak" force networks in the pentagon packing, but our simulation data provide also evidence for a large class of ''very weak" forces carried mainly by vertex-to-edge contacts. The strong force chains are mostly composed of edge-to-edge contacts with a marked zig-zag aspect and a decreasing exponential probability distribution as in a disk packing.
Published: 2007

25. Force transmission in a packing of pentagonal particles

Author: Robert Peyroux, Farhang Radjai, Emilien Azéma, Gilles Saussine, Laboratoire de Mécanique et Génie Civil ( LMGC ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Physique et Mécanique des Milieux Granulaires ( PMMG ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Département recherche et développements ( R&D - SNCF ), SNCF, Laboratoire de Mécanique et Génie Civil (LMGC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Physique et Mécanique des Milieux Granulaires (PMMG), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Département recherche et développements (R&D - SNCF)
Subjects: Materials science, Strong interaction, FOS: Physical sciences, Physics - Classical Physics, Atomic packing factor, 01 natural sciences, 010305 fluids & plasmas, Contact force, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], 0103 physical sciences, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Contact dynamics, 010306 general physics, Anisotropy, Shearing (physics), Condensed matter physics, Classical Physics (physics.class-ph), force transmission, Pentagon, Condensed Matter::Soft Condensed Matter, polygon, Zigzag, [ PHYS.MECA.MEMA ] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [ SPI.MECA.MEMA ] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Granular, texture
Abstract: Publié dans Physical Review E; International audience; We perform a detailed analysis of the contact force network in a dense confined packing of pentagonal particles simulated by means of the contact dynamics method. The effect of particle shape is evidenced by comparing the data from pentagon packing and from a packing with identical characteristics except for the circular shape of the particles. A counterintuitive finding of this work is that, under steady shearing, the pentagon packing develops a lower structural anisotropy than the disk packing. We show that this weakness is compensated by a higher force anisotropy, leading to enhanced shear strength of the pentagon packing. We revisit ''strong" and ''weak" force networks in the pentagon packing, but our simulation data provide also evidence for a large class of ''very weak" forces carried mainly by vertex-to-edge contacts. The strong force chains are mostly composed of edge-to-edge contacts with a marked zig-zag aspect and a decreasing exponential probability distribution as in a disk packing.
Published: 2007
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26. Application of dynamic programming to optimal energy management of grid-independent hybrid railcars

Author: Marco Sorrentino, Kréhi Serge Agbli, Daniel Hissel, Frédéric Chauvet, Tony Letrouve, Università degli Studi di Salerno (UNISA), Clean Horizon Consulting (Clean Horizon), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), and SNCF
Subjects: dynamic programming, Battery (electricity), energy management, Computer science, Energy management, degree of hybridization, 020209 energy, Mechanical Engineering, [SPI.NRJ]Engineering Sciences [physics]/Electric power, 020302 automobile design & engineering, Control engineering, railcar hybridization, 02 engineering and technology, Train transportation, Grid, energetic macroscopic representation, [SPI.AUTO]Engineering Sciences [physics]/Automatic, Dynamic programming, 0203 mechanical engineering, [PHYS.MECA.THER]Physics [physics]/Mechanics [physics]/Thermics [physics.class-ph], 0202 electrical engineering, electronic engineering, information engineering, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Energetic macroscopic representation
Abstract: International audience
Published: 2020
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27. Sizing method by optimization with energy management – Application to electrical hybrid train

Author: Marie Poline, Laurent Gerbaud, Ali Castaing, Frédéric Chauvet, Julien Pouget, Laboratoire de Génie Electrique de Grenoble (G2ELab), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), G2Elab-Modèles, Méthodes et Méthodologies Appliqués au Génie Electrique (G2Elab-MAGE), Laboratoire de Génie Electrique de Grenoble (G2ELab ), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), SNCF : Innovation & Recherche, SNCF, and Département recherche et développements (R&D - SNCF)
Subjects: energy management, Computer science, Energy management, 020209 energy, Mechanical Engineering, [SPI.NRJ]Engineering Sciences [physics]/Electric power, 020208 electrical & electronic engineering, 02 engineering and technology, Condensed Matter Physics, SQP, 7. Clean energy, Automotive engineering, Sizing, electric hybrid train, Electronic, Optical and Magnetic Materials, sizing, Mechanics of Materials, 0202 electrical engineering, electronic engineering, information engineering, Electrical and Electronic Engineering, optimization
Abstract: WOS:000470074400013; International audience; In France, most of the trains are electrical and some are fed by 1500V DC voltage. When a train is travelling, the power consumption creates a voltage drop. Therefore, below a certain limit, the train has to slow down its speed. This limitation prevents the increase of traffic in some area which needs an electric reinforcement. This paper proposes to use embedded storage systems to support the voltage of the catenary. The main issue is: how to size such an energy storage system? In this way, several aspects (e.g.: the energy management strategy) have to be taken into account. The paper deals with an optimization-based sizing method for the embedded energy storage systems. The proposed method takes into account the energy management strategy in the sizing by optimization. A comparison is made between the use of batteries or supercapacitors.
Published: 2019
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28. Simultaneous optimization of sizing and energy management—Application to hybrid train

Author: Marie Poline, Julien Pouget, Frédéric Chauvet, Laurent Gerbaud, Laboratoire de Génie Electrique de Grenoble (G2ELab), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), G2Elab-Modèles, Méthodes et Méthodologies Appliqués au Génie Electrique (G2Elab-MAGE), Laboratoire de Génie Electrique de Grenoble (G2ELab ), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), SNCF : Innovation & Recherche, SNCF, and Département recherche et développements (R&D - SNCF)
Subjects: Mathematical optimization, Optimization problem, General Computer Science, Computer science, Energy management, Determinist algorithm, 010103 numerical & computational mathematics, 02 engineering and technology, Hybrid diesel train, 7. Clean energy, 01 natural sciences, Theoretical Computer Science, Co-Optimization, 0202 electrical engineering, electronic engineering, information engineering, 0101 mathematics, Sizing, Sequential quadratic programming, Numerical Analysis, Applied Mathematics, [SPI.NRJ]Engineering Sciences [physics]/Electric power, Power (physics), Dynamic programming, Modeling and Simulation, 020201 artificial intelligence & image processing, Embodied energy, Energy (signal processing)
Abstract: WOS:000458127000025; International audience; The increasing railway traffic and the environmental issue demand to find new solutions to provide energy to autonomous train (train with embedded energy sources such as diesel power supply). Using hybrid diesel train with embedded storage elements is an interesting technical solution but this kind of multisource system presents new scientific and methodology challenges. Thus, in the paper, the problematic focus on the design and the energy management of the different sources for this system. Moreover, these two fields are linked to each other. Indeed, there is a strong influence of the sizing on the energy management but the reverse is also true. The paper deals with a new optimization approach to perform the design of both the hybrid sources sizing and their energy management. The multi-sources system is represented by a power flow model and the energy management strategy is based on a frequency approach and on dynamic programming. This direct optimization problem is solved by the Sequential Quadratic Programming (SQP) algorithm. Thus, in the paper, this optimization approach is applied to a real railway study case. A comparison is made between two cases with different energy management methods.
Published: 2019
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29. X-ray CT analysis of the evolution of ballast grain morphology along a Micro-Deval test: key role of the asperity scale

Author: Gaël Combe, Ivan Deiros Quintanilla, Fabrice Emeriault, Charles Voivret, Jean-Francois Ferellec, Laboratoire sols, solides, structures - risques [Grenoble] (3SR ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), GéoMécanique, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Département recherche et développements (R&D - SNCF), and SNCF
Subjects: Ballast, Materials science, [SPI.GCIV.GEOTECH]Engineering Sciences [physics]/Civil Engineering/Géotechnique, 0211 other engineering and technologies, Scalar (physics), General Physics and Astronomy, Geometry, 02 engineering and technology, Surface finish, Edge (geometry), Tracking (particle physics), Track (rail transport), 01 natural sciences, Mechanics of Materials, 0103 physical sciences, General Materials Science, 010306 general physics, Asperity (geotechnical engineering), ComputingMilieux_MISCELLANEOUS, Smoothing, 021101 geological & geomatics engineering
Abstract: Ballast grains in railway tracks progressively wear due to the efforts exerted by the continuous passage of trains and the periodic maintenance operations. The initial sharp edges and vertices of the grains tend to become smoother and the surface texture is removed. This change in morphology plays a key role on the proper behaviour of the ballast layer and, consequently, on the frequency maintenance required on the track. The object of this paper is to improve the understanding of the wear process by tracking the morphology of a sample of grains submitted to an accelerated ageing using the Micro-Deval standard test. To this goal, X-ray Computed Tomography is used to scan a sample of grains at different states of wear and the resulting images are compared using 3D image analysis. A description of morphology evolution at different scales is provided using scalar parameters and spherical harmonic analysis, proving that the general form is not significantly changed during a standard Micro-Deval test. Thus a detailed analysis at the asperity level is performed, showing the key role of the edge broadening and vertex smoothing phenomena on ballast wear.
Published: 2019
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30. Numerical study of particle dispersion emitted from train brakes in underground station

Author: Durand, Antoine, Mehel, Amine, Murzyn, Frédéric, PUECH, Samuel, LARRARTE, Frédérique, Cadic, Ifsttar, Département recherche et développements (R&D - SNCF), SNCF, École Supérieure des Techniques Aéronautiques et de Construction Automobile (ESTACA), Eau et Environnement (IFSTTAR/GERS/EE), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-PRES Université Nantes Angers Le Mans (UNAM), and RP2-E18137 CIFRE - ESTACA via sncf (M. Durand) (01/03/2018 - 31/12/2099)
Subjects: [SPI]Engineering Sciences [physics], STATION SOUTERRAINE, DISPERSION, FREINAGE, [SPI] Engineering Sciences [physics], PARTICULE, POLLUTION ATMOSPHERIQUE, TRAIN
Abstract: Air pollution has become a major issue since it is responsible for several adverse health effects. Among pollutants, exposure to particle matter (PM) including ultrafine (UFP) and nanoparticles has been defined as particularly hazardous. It was shown that PM exposure increases the risks of cardiovascular and respiratory diseases. Particles size is strongly linked to their dangerousness. The smaller they are, the higher their deposition rate and their ability to penetrate respiratory and blood system are. Former studies carried out in underground train stations across the world revealed that particle concentration rates can reach higher levels than outdoor.Thus, commuting is one of the main contribution to daily personal exposure to particulate pollutants This work aims to increase our knowledge about particle dynamics issued from trains brake discs in the context of an underground station. Then, the influence of the flow surrounding a train passing a station at low speed is investigated. To assess the particle dynamics for these three specific size ranges, three-dimensional numerical simulations are conducted using the commercial code Fluent 19.2. The Eulerian-Lagrangian approach is used allowing a fine tracking of particles in the flow around the rolling stock. The turbulent mean flow is computed using Unsteady Reynolds-Averaged Navier-Stokes (URANS) through the RNG k-µ turbulence model. Particles dispersion from disks brakes to the station is computed with the Discrete Phase Model. Our methodology is described in the first part of this paper, followed by the results of flow computation. Train-induced flow influence on brake particle dispersion is discussed in the third section. This paper ends with our conclusions about regions of interested highlighted by the present study and perspective for further studies to assess properly particle dispersion in underground stations., La pollution de l'air est devenue un problème majeur puisqu'elle est responsable de plusieurs effets néfastes sur la santé. Parmi les polluants, l'exposition aux particules (PM), y compris les particules ultrafines (UFP) et les nanoparticules, a été définie comme particulièrement dangereuse. Il a été démontré que l'exposition aux particules augmente les risques de maladies cardiovasculaires et respiratoires. La taille des particules est fortement liée à leur dangerosité. Plus ils sont petits, plus leur taux de dépôt et leur capacité à pénétrer les voies respiratoires et le système sanguin sont élevés. Des études antérieures menées dans des gares souterraines à travers le monde ont révélé que les taux de concentration de particules peuvent atteindre des niveaux plus élevés qu'à l'extérieur, de sorte que les trajets domicile-travail constituent l'une des principales contributions à l'exposition quotidienne des personnes aux particules polluantes. Ensuite, l'influence de l'écoulement autour d'un train qui passe à faible vitesse devant une gare est étudiée. Pour évaluer la dynamique des particules pour ces trois plages de tailles spécifiques, des simulations numériques tridimensionnelles sont effectuées à l'aide du code commercial Fluent 19.2. L'approche eulérienne-lagrangienne permet un suivi fin des particules dans le flux autour du matériel roulant. Le débit moyen turbulent est calculé à l'aide du modèle de turbulence Unsteady Reynolds-Averaged Navier-Stokes (URANS) à l'aide du modèle RNG k-µ. La dispersion des particules des freins à disque vers la station est calculée à l'aide du modèle de phase discrète. Notre méthodologie est décrite dans la première partie de ce document, suivie des résultats du calcul des flux. L'influence du débit induit par le train sur la dispersion des particules de freinage est abordée dans la troisième section. Le présent document se termine par nos conclusions sur les régions d'intérêt mises en évidence par la présente étude et les perspectives d'autres études visant à évaluer correctement la dispersion des particules dans les stations souterraines.
Published: 2019

31. IEEE VTS Motor Vehicles Challenge 2019 – Energy Management of a dual-mode locomotive

Author: Frédéric Chauvet, Tony Letrouve, Walter Lhomme, Loic Boulon, Florian Tournez, Alain Bouscayrol, Samir Jemei, Laboratoire d’Électrotechnique et d’Électronique de Puissance - ULR 2697 (L2EP), Centrale Lille-Université de Lille-Arts et Métiers Sciences et Technologies, HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Département recherche et développements (R&D - SNCF), SNCF, Centrale Lille-Haute Etude d'Ingénieurs-Université de Lille-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Computer science, business.industry, Energy management, 020208 electrical & electronic engineering, [SPI.NRJ]Engineering Sciences [physics]/Electric power, 020302 automobile design & engineering, 02 engineering and technology, Propulsion, 7. Clean energy, Automotive engineering, Energy storage, [SPI.AUTO]Engineering Sciences [physics]/Automatic, Software, 0203 mechanical engineering, 0202 electrical engineering, electronic engineering, information engineering, [PHYS.MECA.THER]Physics [physics]/Mechanics [physics]/Thermics [physics.class-ph], Pantograph, Electricity, Session (computer science), [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], business, Overhead line
Abstract: International audience; After the success of the first two international IEEE VTS Motor Vehicles Challenges launched in 2016 at Hangzhou, China, and in 2017 at Belfort, France during the IEEE Vehicle Power and Propulsion Conference (VPPC), this paper proposes the technical framework of the third challenge. For the edition of 2019 the challenge is focused on a dual-mode locomotive. The locomotive is powered either from a DC overhead line through a pantograph or using an on-board fuel cell with battery and supercapacitors. By taking into account the operational costs the challenge issue is to propose an Energy Management Strategy (EMS) to minimize the consumption of the electricity network and hydrogen; and to increase the lifetime of the fuel cell and energy storage system. The locomotive model will be provided to the participants using Matlab-Simulink software. Both industrial and academic teams are welcomed to propose their own EMS. The participants with top scoring will be invited to present their results in a special session at the 2019 IEEE VPPC.
Published: 2018

32. Optimal sizing method with energy management \textendash application to electric hybrid train

Author: Poline, Marie, Gerbaud, Laurent, Pouget, Julien, Chauvet, Frédéric, Castaing, Ali, Chadebec, Olivier, Laboratoire de Génie Electrique de Grenoble (G2ELab), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), SNCF : Innovation & Recherche, SNCF, and Département recherche et développements (R&D - SNCF)
Subjects: [SPI.NRJ]Engineering Sciences [physics]/Electric power, ComputingMilieux_MISCELLANEOUS, [SPI.NRJ] Engineering Sciences [physics]/Electric power
Abstract: International audience
Published: 2018

33. Guided Machine Learning for power grid segmentation

Author: Antoine Marot, Benjamin Donnot, Sami Tazi, Patrick Panciatici, Donnot, Benjamin, Département recherche et développements (R&D - SNCF), and SNCF
Subjects: FOS: Computer and information sciences, Computer science, 020209 energy, Machine Learning (stat.ML), 02 engineering and technology, Machine learning, computer.software_genre, Statistics - Applications, [STAT.AP] Statistics [stat]/Applications [stat.AP], Statistics - Machine Learning, 0202 electrical engineering, electronic engineering, information engineering, Segmentation, Applications (stat.AP), Cluster analysis, [STAT.AP]Statistics [stat]/Applications [stat.AP], business.industry, [SPI.NRJ]Engineering Sciences [physics]/Electric power, AC power, Grid, Control room, Visualization, Task analysis, Graph (abstract data type), Artificial intelligence, business, computer, [SPI.NRJ] Engineering Sciences [physics]/Electric power
Abstract: International audience; The segmentation of large scale power grids into zones is crucial for control room operators when managing the grid complexity near real time. In this paper we propose a new method in two steps which is able to automatically do this segmentation, while taking into account the real timecontext, in order to help them handle shifting dynamics. Our method relies on a ”guided” machine learning approach. As a first step, we define and compute a task specific ”Influence Graph” in a guided manner. We indeed simulate on a grid state chosen interventions, representative of our task of interest (managing active power flows in our case). For visualization and interpretation, we then build a higher representation of the gridrelevant to this task by applying the graph community detection algorithm Infomap on this Influence Graph. To illustrate ourmethod and demonstrate its practical interest, we apply it on commonly used systems, the IEEE-14 and IEEE-118. We show promising and original interpretable results, especially on the previously well studied RTS-96 system for grid segmentation. We eventually share initial investigation and results on a large- scale system, the French power grid, whose segmentation had a surprising resemblance with RTE’s historical partitioning
Published: 2018

34. Étude expérimentale du contact électrique roue/rail

Author: Loete, Florent, Kaza, Guy-Leon, Testé, Philippe, Landfried, Romaric, Houzé, Frédéric, Chollet, Hugues, Lorang, Xavier, Laboratoire Génie électrique et électronique de Paris (GeePs), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Heuristique et Diagnostic des Systèmes Complexes [Compiègne] (Heudiasyc), Université de Technologie de Compiègne (UTC)-Centre National de la Recherche Scientifique (CNRS), Génie des Réseaux de Transport Terrestres et Informatique Avancée (IFSTTAR/COSYS/GRETTIA), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Communauté Université Paris-Est, Département recherche et développements (R&D - SNCF), and SNCF
Subjects: [SPI]Engineering Sciences [physics], ComputingMilieux_MISCELLANEOUS
Abstract: National audience
Published: 2017

35. Waves, modes and properties with a major impact on dynamic pantograph-catenary interaction

Author: Olivier Vo Van, Jean-Pierre Massat, Etienne Balmes, Laboratoire Procédés et Ingénierie en Mécanique et Matériaux (PIMM), Conservatoire National des Arts et Métiers [CNAM] (CNAM)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), Département recherche et développements (R&D - SNCF), SNCF, Laboratoire de Mécanique des Systèmes et des Procédés (LMSP), Centre National de la Recherche Scientifique (CNRS), Arts et Métiers ParisTech, HESAM Université (HESAM), Laboratoire de mécanique des sols, structures et matériaux (MSSMat), CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and SDTools
Subjects: Engineering, Matériaux [Sciences de l'ingénieur], Acoustics and Ultrasonics, Wave propagation, wave propagation, 02 engineering and technology, Contact force, [SPI.MAT]Engineering Sciences [physics]/Materials, Design objective, catenary geometry, 0203 mechanical engineering, Catenary, 0202 electrical engineering, electronic engineering, information engineering, Parametric statistics, business.industry, Mécanique [Sciences de l'ingénieur], Mechanical Engineering, 020208 electrical & electronic engineering, Structural engineering, Mechanics, [SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph], Condensed Matter Physics, frequency coincidences, Element model, Pantograph-catenary dynamics, 020303 mechanical engineering & transports, Mechanics of Materials, Drop tests, Pantograph, business
Abstract: International audience; Understanding the dynamic behavior of the pantograph-catenary system is crucial for design improvement, but many factors inuence the contact force, which is the main design objective. To give a proper un-derstanding of dynamic characteristics, the paper uses a combination of mass drop tests on a catenary, analytic models and parametric _nite element model simulations allowing a ne analysis of the inuence of train speed. The _rst contributor to contact force variations is the geometry of the catenary under gravity loading. This parameter is however shown to be insu_cient to explain higher frequency e_ects. The second contributor is the propagation of waves in the contact and messenger wires. The inuence of wave dis-persion is _rst demonstrated, which emphasizes the importance of considering the bending sti_ness. Wave compensation by droppers and reections at the mast are then shown to be important. Characteristic times associated with wave group velocities are _nally used to explain the series of harmonic contributions visible in spectra in the catenary and pantograph frames. Finally, modes are shown to play a role particularly when their frequencies coincide with other contributions. The notion of mode groups, associated wave velocities and relevant design variables are discussed. Several observations pave the way for future work on catenarydesign.
Published: 2017
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36. Introduction of variability into pantograph–catenary dynamic simulations

Author: Olivier Vo Van, Christophe Laurent, Jean-Pierre Massat, Etienne Balmes, Laboratoire Procédés et Ingénierie en Mécanique et Matériaux (PIMM), Conservatoire National des Arts et Métiers [CNAM] (CNAM)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), Département recherche et développements (R&D - SNCF), SNCF, and Vibrateam
Subjects: Pantograph–catenary interaction, 0209 industrial biotechnology, Engineering, 02 engineering and technology, Coincidence, Mécanique: Vibrations [Sciences de l'ingénieur], 020901 industrial engineering & automation, 0203 mechanical engineering, Catenary, medicine, Variability, Safety, Risk, Reliability and Quality, Electrical impedance, Dimensioning, Simulation, business.industry, Mechanical Engineering, [SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph], Stiffness, Sobol sequence, Structural engineering, Dynamic simulation, 020303 mechanical engineering & transports, Automotive Engineering, Pantograph, medicine.symptom, business
Abstract: In railways, electrical current is generally collected by the train through a complex coupledmechanical system composed of a pantograph and a catenary. Dynamic phenomena that occur duringtheir interaction are still not fully understood. Furthermore, the system behaviour is sensitive to numerousparameters and thus highly variable. The first contribution of this thesis is a detailed analysis of thepantograph-catenary dynamic interaction separating phenomena due to the dynamic response of the pantographto the catenary geometry from wave propagations, reflections and transmissions that occur in thecatenary. The coincidence of frequencies or characteristic times is then shown to explain most variationsin the quantities of interest. Moreover, droppers surrounding the mast have been shown to be particularlyimportant in dynamic interaction. Ratio of wire impedances and sum of wave velocities also appeared tobe dimensioning quantities for catenary design. The second contribution was to reduce epistemic uncertaintylinked with model parameters such as catenary damping, contact stiffness and element size. Thefinal contribution was to use the model in a configuration with random parameters. An initial step was tostatistically characterise physical catenary parameters using available measurements. From this randommodel, ranking of uncertainties using Sobol indices on static and dynamic criteria was shown to be possible.An absence of correlation between geometric and dynamic criteria was also found, which has notableimplications for maintenance policies. The high number of sensitivity studies also gave the occasion tohighlight the maturity of simulation tool and propose directions for further work on design, maintenance orcertification of pantographs and catenaries.
Published: 2014
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37. XFEM Crack Propagation Under Rolling Contact Fatigue

Author: B. Trollé, Anthony Gravouil, S.H. Mai, Marie-Christine Baietto, T.M.L. Nguyen-Tajan, Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] (LaMCoS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), SNCF : Innovation & Recherche, SNCF, Mécanique Multiéchelle pour les solides (MIMESIS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Département recherche et développements (R&D - SNCF), Afzali, and M and Lefebvre
Subjects: Keynotes: Fatigue crack growth simulation, Engineering, Cost efficiency, XFEM, business.industry, Rolling-sliding contact fatigue of rails, Fracture mechanics, General Medicine, Structural engineering, Track (rail transport), Grinding, Fatigue crack growth simulation, [SPI]Engineering Sciences [physics], Software, Residual stress, Dynamical simulation, business, Engineering(all), Extended finite element method
Abstract: 5th Fatigue Design Conference, Cetim, Senlis, FRANCE, NOV 27-28, 2013; International audience; To assure the security, heavy monitoring and maintenance procedures for the fatigue of rails are set up by infrastructure managers. In order to go towards a more cost efficient railway system, it is essential to optimize the maintenance of rails: frequency of monitoring, rail replacement strategy, grinding policy... To progress in this area, a numerical modeling tool has been developed thanks to a long-term collaboration between railway organizations (SNCF, RFF, RATP), rail producer (Tata Steel) and research institutes and universities (INRETS, LMS, MECAMIX, INSA) within the IDR2 consortium (Initiative for Development and for Research on Rail). This modelling starts with a dynamical simulation of the vehicle rolling on a track, from which the cyclic mechanical state of the rail is calculated by means of a 3D finite element simulation and an original and time-cost efficient direct stationary algorithm. Finally, a fatigue analysis of the rail is performed with the Dang Van criterion. The modeling tool has been recently completed with the simulation of the crack propagation in the rails. A two-scale frictional contact fatigue crack model developed within the X-FEM framework is used to solve the crack problem. Using this approach, contact and friction between the crack faces is taken into account in the simulation. Realistic residual stresses, coming from dedicated software developed by SNCF are introduced in the propagation simulation via projection of the asymptotic mechanical fields. 2D Crack growth is performed taking into account the residual stresses. The results highlight their influence on the crack growth rate. Finally 3D preliminary results are introduced.
Published: 2013
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38. Use of a bituminous mixture layer in high-speed line trackbeds

Author: Diego Ramirez Cardona, Hervé Di Benedetto, Cédric Sauzéat, Gilles Saussine, Nicolas Calon, Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS), École Nationale des Travaux Publics de l'État (ENTPE), École Nationale des Travaux Publics de l'État (ENTPE)-Ministère de l'Ecologie, du Développement Durable, des Transports et du Logement, SNCF Direction de l'ingénierie, Division Expertise - Recherche - Innovation (IG.LG.ERI), Département recherche et développements (R&D - SNCF), and SNCF
Subjects: Optimal design, Engineering, business.industry, Constitutive equation, 0211 other engineering and technologies, Modulus, 020101 civil engineering, 02 engineering and technology, Building and Construction, Structural engineering, Viscoelasticity, Dashpot, 0201 civil engineering, [SPI.GCIV]Engineering Sciences [physics]/Civil Engineering, Asphalt, 021105 building & construction, Line (geometry), General Materials Science, Composite material, business, Layer (electronics), ComputingMilieux_MISCELLANEOUS, Civil and Structural Engineering
Abstract: Feedback on the use of a sub-ballast bituminous layer in a ballasted high-speed line (HSL) is evaluated in this paper. Conclusions are drawn on the relation between the thermo-viscoelastic behaviour of bituminous materials and the improvement in maintenance needs observed on the studied HSL. The case study is a 3 km long experimental zone of the French East-European high-speed line (EE HSL) built with a bituminous mixture sub-ballast layer. In service since 2007, the EE HSL test section has required fewer maintenance operations compared to adjacent sections with conventional structure. Thermo-viscoelastic properties of a bituminous mixture were characterized to understand and explain the contribution of a bituminous sub-ballast layer to the track behaviour. Improved 3D complex modulus tests were performed on laboratory-compacted cylindrical specimens using sinusoidal loading. A constitutive model, called 2S2P1D (2 Springs, 2 Parabolic, 1 Dashpot), developed in the LTDS/ENTPE Laboratory, University of Lyon, was used to simulate the linear viscoelastic (LVE) behaviour of the tested material. The results were analysed in the light of the working conditions and typical loadings of the EE HSL. The results of this study contribute to the definition of an optimal design method for ballasted HSL tracks with bituminous sub-ballast layers.
Published: 2016
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39. Numerical Study of Railway Track Dynamics : Case of a Transition Zone

Author: ARLAUD, Elodie, COSTA D'AGUIAR, Sofia, BALMES, Etienne, FAUSSURIER, Guillaume, Laboratoire Procédés et Ingénierie en Mécanique et Matériaux (PIMM), Conservatoire National des Arts et Métiers [CNAM] (CNAM)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), Département recherche et développements (R&D - SNCF), and SNCF
Subjects: Mécanique: Vibrations [Sciences de l'ingénieur], [SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph]
Abstract: International audience; The main objective of this paper is to present an innovative numerical tool to represent the track and platform dynamic behavior under passing trains. Dynavoie is currently being developed for engineering purposes at SNCF. It is specifically designed to correctly reproduce the track and platform dynamic behaviors in the time domain. This model is based on the Finite Element Method (FEM), adapted to the railway track using model reduction techniques. Taking advantage of the periodicity of the track introduced by the regular sleeper spacing, one or several basic slices containing all the geometric properties of the structure can be identified. Static and periodic responses of these slices are computed. Then, reduction is performed using these deformations.Thus the number of degrees of freedom of the model is highly reduced. This reduction induces a decrease in computation time with limited accuracy loss in the representation of track dynamics. The methodology will be further described in this paper. The second novelty of this work is to use this model to analyze the dynamic behavior of a transition zone located in a French high speed line.
Published: 2016

40. Reverse engineering of a railcar prototype via energetic macroscopic representation approach

Author: Frédéric Chauvet, Kréhi Serge Agbli, Daniel Hissel, Marco Sorrentino, Julien Pouget, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Salerno (UNISA), Département recherche et développements (R&D - SNCF), and SNCF
Subjects: Reverse engineering, Engineering, Energetic macroscopic representation, Railcar, Regenerable braking, Powertrain, Multiphysics modelling, Hybridization analysis, 020209 energy, Complex system, Energy Engineering and Power Technology, 02 engineering and technology, Propulsion, computer.software_genre, 7. Clean energy, Traction motor, [SPI.AUTO]Engineering Sciences [physics]/Automatic, Consistency (database systems), Component (UML), 0202 electrical engineering, electronic engineering, information engineering, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Simulation, Renewable Energy, Sustainability and the Environment, business.industry, 020208 electrical & electronic engineering, [SPI.NRJ]Engineering Sciences [physics]/Electric power, Control engineering, Energy consumption, Fuel Technology, Nuclear Energy and Engineering, [PHYS.MECA.THER]Physics [physics]/Mechanics [physics]/Thermics [physics.class-ph], business, computer
Abstract: International audience; Energetic Macroscopic Representation (EMR) modelling approach is proposed to perform model-based reverse-engineering of a new railcar range, having six propulsion units, each consisting of a diesel engine and a traction motor. Particularly, EMR intrinsic features were exploited to perform phenomenological structuration of power flows, thus allowing proper and comprehensive modelling of complex systems, such as the under-study railcar. Based on some prospective real trips, selected in such a way as to enable realistic evaluation of effective railcar effort, EMR-based prediction of railcar energy consumption is performed. Furthermore, physical consistency of each powertrain component operation was carefully verified. The suitability of EMR approach was thus proven effective to perform reverse-engineering of known specifications and available experimental data, with the final aim of reconstructing a high fidelity computational tool that meets computational burden requirements for subsequent model-based tasks deployment. Finally, specific simulation analyses were performed to evaluate the potential benefits attainable through electric hybridization of the original powertrain.
Published: 2016

41. Track-bed mechanical behaviour under the impact of train at different speeds

Author: Tongwei Zhang, Yu-Jun Cui, Sofia Costa D’Aguiar, Matheus Peixoto De Oliveira, Nicolas Calon, Francisco Lamas-Lopez, Laboratoire Navier (navier umr 8205), École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), SNCF, SNCF : Innovation & Recherche, and Département recherche et développements (R&D - SNCF)
Subjects: Track bed, Engineering, business.industry, Capacitive sensing, Acoustics, 0211 other engineering and technologies, 020101 civil engineering, Ranging, 02 engineering and technology, Geotechnical Engineering and Engineering Geology, Accelerometer, 0201 civil engineering, [SPI]Engineering Sciences [physics], Amplitude, Lateral earth pressure, 11. Sustainability, Range (statistics), Train, business, Simulation, 021101 geological & geomatics engineering, Civil and Structural Engineering
Abstract: International audience; This paper aims to study the influence of train speed on the mechanical behaviour of track-bed materials based on field data recorded at a representative site of the conventional French network. Capacitive accelerometers soil pressure gauges were installed in track-bed layers. The Intercity train was selected to perform this study as it is the most frequent train running on this site. In total, 1790 records corresponding to Intercity train passages were taken into account, with train speeds ranging from 60 to 200 km/h. The vertical strains of different layers were estimated by integrating the signals of accelerometers installed at different depths. It is observed that when train speed increased in the considered range, the traffic loadings, in terms of dynamic stress transmitted to track-bed materials, were amplified about 10%. However, the vertical strains of track-bed materials were also amplified by 2 in the same range of speeds. These amplifications appear mainly in shallower layers. The stress strain amplitude ratios for all the recorded trains were calculated to analyse the evolution of resilient moduli (M-r) of track-bed materials. It is found that Mr of interlayer soil decreased by approximately 25% when train speed increased from 60 to 200 km/h. (C) 2016 The Japanese Geotechnical Society. Production hosting by Elsevier B.V.
Published: 2016
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42. Study of nonlinear behaviors and modal reductions for friction destabilized systems. Application to an elastic layer

Author: Andréa Loyer, Olivier Chiello, Xavier Lorang, Jean-Jacques Sinou, Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS), Laboratoire Transport et Environnement (IFSTTAR/LTE), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université de Lyon, Département recherche et développements (R&D - SNCF), and SNCF
Subjects: Engineering, Acoustics and Ultrasonics, Discretization, [MATH.MATH-DS]Mathematics [math]/Dynamical Systems [math.DS], reduction, 02 engineering and technology, [SPI.MECA.SOLID]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Solid mechanics [physics.class-ph], 01 natural sciences, law.invention, [PHYS.MECA.STRU]Physics [physics]/Mechanics [physics]/Structural mechanics [physics.class-ph], 0203 mechanical engineering, law, Control theory, [PHYS.MECA.SOLID]Physics [physics]/Mechanics [physics]/Solid mechanics [physics.class-ph], 0103 physical sciences, Disc brake, 010301 acoustics, [PHYS.MECA.VIBR]Physics [physics]/Mechanics [physics]/Vibrations [physics.class-ph], Noise (signal processing), business.industry, Mechanical Engineering, structural dynamic, [SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph], [SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph], Condensed Matter Physics, Finite element method, friction-induced vibration, Nonlinear system, 020303 mechanical engineering & transports, Modal, [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], Mechanics of Materials, Transient (oscillation), business, Reduction (mathematics)
Abstract: International audience; As noise reduction tends to be part of environmental directives, predicting squeal noise generated by disc brakes is an important industrial issue. It involves both the transient and stationary nonlinear dynamics of self-excited systems with frictional contact. Time simulation of the phenomenon is an attractive option for reducing experiment costs. However, since such computations using full finite element models of industrial disc brake systems is time-consuming, model reduction has to be performed. In this paper, both the transient and stationary nonlinear behaviors of the friction destabilized system and the effect of dynamical reduction on the nonlinear response of a simple friction destabilized system are carried out. The first part provides a description of the general modeling retained for friction destabilized systems. Then, discretization and solving processes for the stability analysis and the temporal evolution are presented. The third part presents an analysis of a sliding elastic layer for different operating conditions, in order to better understand the nonlinear behavior of such systems. Finally, spatial model reduction is performed with different kinds of reduction bases in order to analyze the different effects of modal reductions. This clearly shows the necessity of including static modes in the reduction basis and that nonlinear interactions between unstable modes are very difficult to represent with reduced bases. Finally, the proposed model and the associated studies are intended to be the benchmark cases for future comparison.
Published: 2012
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43. Cranial reconstruction after a post-craniotomy empyema

Author: T. Bron, Y. Riah, C. Dellavolpe, D. Casanova, Y. Reynier, J.-F. Chabas, J.-M. Kaya, Khrestchatisky, Michel, Département recherche et développements (R&D - SNCF), SNCF, Neurobiologie des interactions cellulaires et neurophysiopathologie - NICN (NICN), Centre National de la Recherche Scientifique (CNRS)-Université de la Méditerranée - Aix-Marseille 2, Institut de génétique humaine (IGH), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Université de la Méditerranée - Aix-Marseille 2-Centre National de la Recherche Scientifique (CNRS)
Subjects: Adult, medicine.medical_specialty, MESH: Empyema, Serratus anterior muscle, medicine.medical_treatment, MESH: Brain Diseases, MESH: Craniotomy, MESH: Bone Substitutes, Free flap, Surgical Flaps, 03 medical and health sciences, 0302 clinical medicine, Scapula, medicine, Humans, Surgical Wound Infection, [SDV.NEU] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], MESH: Surgical Wound Infection, Empyema, Craniotomy, Brain Diseases, MESH: Humans, business.industry, Skull, MESH: Adult, MESH: Surgical Flaps, Plastic Surgery Procedures, medicine.disease, Cranioplasty, 3. Good health, Surgery, medicine.anatomical_structure, 030220 oncology & carcinogenesis, Bone Substitutes, MESH: Reconstructive Surgical Procedures, MESH: Skull, [SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], Female, Osteitis, business, MESH: Female, 030217 neurology & neurosurgery
Abstract: International audience; This article presents a case report of a cranioplasty performed after a post-craniotomy empyema with osteitis. The skull reconstruction was performed using a bioceramic implant and a combined muscular free flap of latissimus dorsi and serratus anterior. This procedure not only provided coverage of a wide skull defect but also allowed the filling of the intracranial dead space. Clinically, we observed an improvement of the patient's preoperative neurological status with a near-complete correction of her right hemiparaesis and phasic disorders. Eight months after the cranioplasty, (1) no recurrence of infection was noticed; (2) no distortion of the skull was noticeable and (3) the patient again experienced a normal social life. Using computed tomography (CT) scan images, we observed a re-expansion of the left cerebral hemisphere without any dead space or extradural collection. The only observable sequelae were a temporoparietal alopecia (10 cm x 4 cm) and a winging of the scapula, induced by the skin graft and the removal of the lower-third of the serratus anterior muscle, respectively. The use of a muscular free flap associated with a customised biomaterial allows a single-stage reconstruction of extensive skull defect (120 cm(2)) in a previously infected area.
Published: 2009
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44. Stochastic heterogeneous material modeling for granular material. Application to wave propagation in ballasted railway track

Author: Régis Cottereau, Lucio Abreu Corrêa, Juan Carlos Quezada, Aguiar, Sofia Costa D., Charles Voivret, Laboratoire de mécanique des sols, structures et matériaux (MSSMat), CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), SNCF, and CSMA
Subjects: Wave propagation, Heterogeneous medium, [PHYS.MECA]Physics [physics]/Mechanics [physics], Ballasted railway track
Abstract: International audience; In this work we consider the description of a granular material as an heterogeneous linear continuum medium and the wave propagation in this continuum medium. The purpose of this modeling is to represent the equivalent stress field obtained in a discrete granular model through a continuum stochastic field of mechanical proprieties. One model was build in a finite element method to identify this continuum stochastic proprieties. We applied this approach in a ballasted railway track. The dynamic equations are solved using a Spectral Element approach using one probabilistic model.
Published: 2015

45. Squeal Complex Eigenvalue Analysis, Advanced Damping Models and Error Control

Author: VERMOT DES ROCHES, Guillaume, CHIELLO, Olivier, BALMES, Etienne, LORANG, Xavier, SDTools, Laboratoire d'Acoustique Environnementale (IFSTTAR/AME/LAE), PRES Université Nantes Angers Le Mans (UNAM)-Université de Lyon-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Arts et Métiers ParisTech, HESAM Université (HESAM), Département recherche et développements (R&D - SNCF), and SNCF
Subjects: [SPI.OTHER]Engineering Sciences [physics]/Other, squeal, damping, reduction, COMPLEX MODES, Mécanique: Vibrations [Sciences de l'ingénieur], REDUCTION, BRUIT, SQUEAL, complex modes, robust design, FREIN, ROBUST DESIGN, DAMPING, CRISSEMENT
Abstract: Eurobrake 2015 - Europe's braking technology conference and exhibition, DRESDEN, ALLEMAGNE, 04-/05/2015 - 06/05/2015; Estimation of brake systems stability related to noise emission is part of the industry state-of-the-art for brake design. Improved assessment of stability would allow better NVH performance from early design stages thus reducing costs related to late redesign and testing. The prediction capability however remains challenged due to the complexity of brake noise phenomena. In particular, integration and resolution of complex systems with damping is a difficult task that is commonly overlooked. This paper proposes two ideas to improve stability estimation. From the solver side, a convergence indicator is proposed to quantify the convergence of the complex eigenvalues for subspace based methods. The error obtained can be directly used to enhance the computation subspace and a priori enhancement is suggested. From the modelling side, a damping strategy based on sub-assembly modal damping ratios is proposed allowing direct exploitation of test measurements or refined sub-assembly simulations for damping estimation. Sub-assembly damping can thus be accounted for at the system level including all possible effects like joint dissipation or composite materials.
Published: 2015

46. Experimental study and modelling of overheating of electrical catenary-pantograph interface for trains supplied with power in station

Author: Bausseron, Thomas, Baucour, Philippe, Glises, Raynal, Chamagne, Didier, Verschelde, Sylvain, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), and SNCF
Subjects: [SPI.NRJ]Engineering Sciences [physics]/Electric power, [PHYS.MECA.THER]Physics [physics]/Mechanics [physics]/Thermics [physics.class-ph], [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], [SPI.AUTO]Engineering Sciences [physics]/Automatic
Abstract: International audience; For railroads and trains, there have been many incidents involving catenary overheating at the contact with the pantograph when a train is supplied with power while standing still. The overheating of the catenary-pantograph interface can sometimes cause the contact wire to break. In order to anticipate the occurrence of such costly problems, the FEMTO-ST Institute has carried out theoretical and experimental studies in collaboration with the French National Railway Company (SNCF) to better understand this phenomenon. First, a 2D transient electrical model was developed for the contact wire. This allows the current distribution in the wire to be estimated to obtain an accurate measure of the internal heat generation. The heat produced by the interface was considered and split between the catenary and pantograph with an analytical model. Finally, the heat transfer equation for the wire under particular boundary conditions was solved for the entire finite difference network based on Euler’s implicit method. The transient modelling results of the wire heating were compared with earlier experimental values, and a parametric study was performed.
Published: 2015

47. Heat Modeling of the Catenary’s Contact Wire During the Electrical Power Supply of Trains in Station

Author: Raynal Glises, Thomas Bausseron, Didier Chamagne, Philippe Baucour, Sylvain Verschelde, Département recherche et développements (R&D - SNCF), SNCF, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Convection, Engineering, business.industry, Thermal resistance, [SPI.NRJ]Engineering Sciences [physics]/Electric power, Mechanical engineering, Thermal conduction, [SPI.AUTO]Engineering Sciences [physics]/Automatic, Heat flux, Catenary, Heat exchanger, [PHYS.MECA.THER]Physics [physics]/Mechanics [physics]/Thermics [physics.class-ph], Pantograph, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], business, Overheating (electricity)
Abstract: International audience; The overheating problem of the railroad catenary at the contact with the pantograph when the train is stopped and electrically fed is responsible of many incidents. This paper describes an experimental study and a numerical model of a catenary/pantograph system used during the preconditioning of the train. Several incidents of wire breakage have highlighted the importance of the catenary/pantograph heating problem, in those incidents the contact wire had melted and broke itself. The experimental setups consists of estimating the contact’s thermal resistance and area in order to calculate which part of the interface heat flux go throught the catenary’s contact wire and which part go throught the pantograph’s collector strip. The numerical model is based on several phenomena as heat conduction into the wires, heat exchange with ambiance through convection, Joule effects and heat flux from the interface.
Published: 2014

48. Fatigue design of railway wheels: a probabilistic approach

Author: Roux, Clément, Lorang, Xavier, Maitournam, Habibou, NGUYEN TAJAN, Mac Lan, Département recherche et développements (R&D - SNCF), SNCF, Laboratoire de mécanique des solides (LMS), École polytechnique (X)-MINES ParisTech - École nationale supérieure des mines de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: railway wheels, [SPI]Engineering Sciences [physics], probabilistic method, multiaxial high-cycle fatigue, damage accumulation, fatigue design
Abstract: International audience; This paper deals with a method to evaluate and optimize the design of railway wheels subjected to multiparameter variable fatigue loading. The fatigue loads are statistically evaluated from in-service measurements. Representative realistic loading paths are built from the knowledge of the influence of various factors (such as train speed and track curvature). Using these paths, the method combines finite element computations and the fatigue equivalence method for damage evaluation in the structure. An extension of the Dang Van fatigue criterion in the high-cycle fatigue finite life domain associated with a damage accumulation law is adopted. The probability of failure of the structure is directly obtained from the interference between a local fatigue equivalent stress and fatigue strength distributions (based on the stress-strength interference approach). The result is useful for the optimization during the design stage or the validation of the fatigue strength of structures.
Published: 2014
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49. Predicting the settlement of coarse granular materials under vertical loading

Author: Juan Carlos Quezada, Farhang Radjai, Pierre Breul, Gilles Saussine, SNCF, Département recherche et développements (R&D - SNCF), Institut Pascal (IP), SIGMA Clermont (SIGMA Clermont)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Physique et Mécanique des Milieux Divisés (PMMD), Laboratoire de Mécanique et Génie Civil (LMGC), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Multidisciplinary, Settlement (structural), Computer science, Compaction, Atomic packing factor, Granular material, Article, Vibration, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Relaxation (physics), Geotechnical engineering, Intensity (heat transfer), Simulation, Parametric statistics
Abstract: Granular materials are widely used in industrial processes despite their complex and poorly understood mechanical behaviour both in static and dynamic regimes. A prototypical example is the settlement and compaction of a granular bed under vibrational loading. The elementary mechanisms of this process are still unclear and there is presently no established theory or methodology to predict the settlement and its statistical variability. By means of a parametric study, carried out on a full-scale track and a critical analysis of density relaxation laws, we introduce a novel settlement model in coarse granular materials under cyclic loading. Our extensive experimental data indicate that the settlement process is governed by three independent parameters strongly correlated with the vibration intensity and initial packing fraction. We show that the mean settlement is well predicted by the model with its parameter values extracted from experimental data.
Published: 2014
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50. 2D fatigue crack propagation in rails taking into account actual plastic stresses

Author: Anthony Gravouil, Benoît Trollé, Si Hai Mai, Marie-Christine Baietto, Benoit Prabel, Mécanique Multiéchelle pour les solides (MIMESIS), Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] (LaMCoS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Département recherche et développements (R&D - SNCF), SNCF, Laboratoire d'études de DYNamique (DYN), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CEA- Saclay (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Rolling contact fatigue, 02 engineering and technology, X-FEM, Fatigue crack propagation, Crack closure, Residual stresses, [SPI]Engineering Sciences [physics], 0203 mechanical engineering, Residual stress, General Materials Science, Stress intensity factor, Stress concentration, business.industry, Crack propagation, Mechanical Engineering, Fracture mechanics, Structural engineering, 021001 nanoscience & nanotechnology, Frictional cracks, Axle, 020303 mechanical engineering & transports, Mechanics of Materials, 0210 nano-technology, business
Abstract: International audience; Due to increase axle loads, repeated passages of the wheels, rolling contact fatigue cracks initiate in the surface or subsurface of the rails. These defects can propagate and lead to the rail failure. A two-scale frictional contact fatigue crack model developed within the X-FEM framework is used to address the cracked rail problem, calculate the stress intensity factors, perform crack propagation and fatigue life prediction. Actual plastic stresses, quantified through a dedicated software developed by SNCF within the consortium IDR2, are taken into account in the propagation simulation via projection of the asymptotic mechanical fields. The effects of those actual plastic stresses are investigated on the crack growth path and rate. Interactions between multiple cracks of a network are also analyzed.
Published: 2014
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