This work is devoted to the application of the micromechanical Gurson-Tvergaard-Needleman (GTN) m... more This work is devoted to the application of the micromechanical Gurson-Tvergaard-Needleman (GTN) model to study the ductile tearing of 12NiCr6 steel. GTN model is widely used to describe the three stages of ductile tearing: nucleation, growth and the coalescence of micro-voids. A new approach based on the identification of the GTN damage model coupled or not with hardening laws using inverse analysis. After identification, the obtained results show a good agreement between the experimental curve tensile test of an axisymetric notched bar (AN2) and those numerically obtained for GTN model coupled with the hardening laws. In order to validate the identified GTN parameters, a simulation of tear test is conducted on 12 NiCr6 steel CT specimen. The numerical results are compared with experimental results found in the literature and a good agreement is obtained. This identification procedure is more accurate than when the damage parameters are identified independently of the hardening laws. Citation: Hadj Miloud, M., Zidane, I., Mendas, M., Coupled identification of the hardening behavior laws and Gurson-Tvergaard-Needleman damage parameters-Validation on tear test of 12NiCr6 CT specimen, Frattura ed Integrità Strutturale, 49 (2019) 630-642.
L’utilisation de procedes de mise en forme de toles minces (emboutissage, hydroformage, formage i... more L’utilisation de procedes de mise en forme de toles minces (emboutissage, hydroformage, formage incremental, …) est tres repandue dans l’industrie. L’amelioration de la prediction des outils de simulation numerique passe par une identification precise de la loi de comportement et des limites de formabilite du materiau constituant la tole. Pour cela, il est souhaitable d’etudier le comportement des toles minces sous des etats de chargements proches de ceux rencontres dans le procede de mise en forme. A cet effet, l’essai de traction biaxial dans le plan de la tole a ete retenu parmi d’autres techniques de sollicitations biaxiales. Dans cette etude, un banc d’essais de traction biaxiale est developpe avec pour objectif d’identifier, a partir d’un meme essai rheologique, la loi de comportement et les limites de formabilite du materiau etudie sous sollicitations statiques ou dynamiques. Ce dispositif experimental est compose de quatre verins hydrauliques disposes horizontalement. La capacite de chaque verin est de 50kN, la vitesse de deplacement sur chaque axe peut atteindre 2m/s. Le pilotage permet d’imposer des rapports de biaxialite lineaires et non-lineaires. Ces essais biaxiaux sont realises sur une eprouvette plane dite « eprouvette cruciforme ». La geometrie optimale de celle-ci est definie a partir d’une etude parametrique realisee sur differentes formes d’eprouvettes cruciformes issues de la litterature. La difficulte principale dans la definition de cette geometrie est de s’assurer de l’apparition de la striction localisee au centre de l’eprouvette afin de maitriser le chemin de deformation impose par le deplacement des verins. Au cours de l’essai, la zone centrale de l’eprouvette est filmee et une technique de correlation d’image est ensuite utilisee en post-traitement pour obtenir le champ de deformation dans l’eprouvette. Par la suite, la procedure experimentale et la geometrie de l’eprouvette sont validees a partir d’une campagne d’essais realisee sur un alliage d’aluminium AA2017. Une procedure specifique de detection de l’apparition de la striction localisee pour cette forme d’eprouvette est definie. Une campagne experimentale est menee sur une tole en alliage d’aluminium AA5086. La courbe limite de formage (CLF) experimentale de cette tole est etablie a partir de la procedure definie precedemment. Enfin, les courbes forces/deplacements experimentales sont utilisees afin d’identifier une loi de comportement par methode inverse a partir d’un modele elements finis (EF) de l’essai biaxial. L’interet d’integrer une grandeur locale dans la procedure d’identification de la loi rheologique est presente. La loi de comportement identifiee est ensuite implementee dans le modele EF de l’essai de traction biaxial afin de determiner la CLF numerique du materiau etudie. Les CLF experimentale et numerique definies a partir de l’essai de traction biaxial sont comparees a celle obtenue sur le meme materiau par un dispositif d’essais de type Marciniak.
Journal of Materials Research and Technology, 2021
Abstract Lamellar cast irons are known as heterogeneous materials. Their overall hardness is dete... more Abstract Lamellar cast irons are known as heterogeneous materials. Their overall hardness is determined by the microhardness of their microstructure contents. This study pertains to extend the indentation size effect (ISE) analyses to these heterogeneous materials. Additionally to macrohardness tests, Vickers microindentation tests were carried out on two cast irons with fully pearlitic matrix. Tensile models for pearlitic steel with both Tabor's law and Taylor's model were introduced in the ISE analyses. Microhardness expressions of the pearlitic phase within these irons were thus obtained. The obtained expressions indicate that the tensile model and the concept of geometrically necessary dislocations (GNDs) can be used to predict the ISE of the pearlitic matrix. For this pearlitic phase, it is shown that the summation of the stresses, associated with the GNDs and SSDs, is more adequate than to consider only one work-hardening stress generated by the two types of dislocations density in the ISE study.
Purpose After more than a century of agreement with the postulate of non-slip condition (adhesion... more Purpose After more than a century of agreement with the postulate of non-slip condition (adhesion to the wall), the study of fluid-solid boundary conditions has shown renewed interest over the past two decades. Although numerous studies have not yet been arrived to a complete description of slip phenomena, however, it appears that the influence of wetting and/or surface roughness results in a weak interaction between fluid and solid; thus, the presence of the slip phenomenon is observed at the fluid-solid interface. The purpose of this paper is to highlight the presence of the slip phenomenon at the lubricated piston skirt-cylinder contact. Design/methodology/approach For this proposal, a modified Reynolds equation and operating characteristics are determined by taking into account the slip conditions at the interface between oil-film and entire cylinder surface. Findings The findings indicate that the operating characteristics are strongly influenced when the slip conditions are ta...
International Journal of Automotive and Mechanical Engineering, 2019
The piston material choice is a major factor in the design stages of internal combustion engines ... more The piston material choice is a major factor in the design stages of internal combustion engines for its importance to improving the durability and the operation reliability during the piston life cycle. Indeed, even as many researches have been conducted for a long time to improve the piston performances in the diesel engine, considerable numbers of piston damages still significantly occur. This research work is an assessment by the finite element method (FEM) of a set of piston materials for the purpose of being used in a direct injection diesel engine. The main objective is to predict stresses concentrations and the clearance between the piston and the cylinder (to avoid metal-metal adhesion) from thermomechanical solicitations. The stresses and deformations are evaluated in a 3D piston model by using ABAQUS software. A first assessment step is performed in heat convection/conduction modes to determine the temperature distribution. Then, this last one is coupled to the pressure f...
A two-dimensional finite element analysis has been performed to investigate hydromechanical and c... more A two-dimensional finite element analysis has been performed to investigate hydromechanical and conventional deep drawing processes. The effects of the fluid structure interaction on the material formability, the strain and the thickness distributions are investigated. Large plastic deformation is observed in the plank at the bottom and the corner of the punch. Plastic deformation distribution results show a difference between the hydromechanical deep drawing process and the conventional deep drawing which is due to the friction effect. This latter represents one of the major features of the hydromechanical deep drawing process. Concerning the formability of the blank, the obtained results show that the hydromechanical deep drawing process gives a better formability than the conventional deep drawing process.
Dans les procédés de mise en forme " classiques " de type emboutissage, la formabilité ... more Dans les procédés de mise en forme " classiques " de type emboutissage, la formabilité des matériaux est déterminée à partir des " courbes limites de formage " (CLF) obtenues à ce jour à partir d'essais statiques. Il apparaît aujourd'hui nécessaire de proposer de nouveaux moyens d'essais permettant de caractériser ces CLF dans des gammes de vitesses et de température adaptées aux nouveaux procédés de mise en forme actuellement développés dans l'industrie automobile ou aéronautique (hydroformage, formage incrémental, électrohydroformage, magnéto-formage, ...). Pour étudier la formabilité de tôles minces, des moyens d'essais dits " classique " sont actuellement disponibles (essai de Marciniak, essai de Nakazima, ...). Toutefois, ces dispositifs expérimentaux présentent un certain nombre d'inconvénients : l'étude de la formabilité est généralement dépendante des phénomènes de frottement se développant à l'interface éprouvett...
In innovative industrial processes such as hydroforming or incremental forming, strain rates up t... more In innovative industrial processes such as hydroforming or incremental forming, strain rates up to 500s-1 can be reached. As a result, experimental setups allowing to obtain large deformations from static to intermediate strain rate levels have to be developed to predict the formability limits of sheet metal materials. The proposed experimental device is a servo-hydraulic testing machine provided with four independent dynamic actuators allowing biaxial tensile tests on cruciform specimen. The main difficulty to define an appropriate cruciform specimen shape is to force the onset of necking in the central region. In this paper, different specimens used in previous studies are numerically investigated through FE simulations. A modified cruciform specimen shape is then proposed and the best set of geometrical dimensions is defined from a parametric study. Finally, the efficiency of the proposed specimen shape is validated by experiments. Numerical and experimental results, i.e., the strain level in the specimen and the onset of necking are compared and discussed to boundary conditions corresponding to an equi-biaxial tensile test.
Le recours a la simulation numerique, pour optimiser les differents procedes de mise en forme des... more Le recours a la simulation numerique, pour optimiser les differents procedes de mise en forme des toles metalliques, necessite une connaissance precise de leur comportement elasto-viscoplastique et de leur limite de formabilite. Le principal objectif de ce travail est de developper une nouvelle technique experimentale capable d'atteindre ces caracteristiques intrinseques du materiau, grâce a l'utilisation d'une geometrie d'eprouvette dediee. Ce dispositif doit etre capable de caracteriser le comportement des toles dans une gamme de vitesses allant du quasi-statique a l'intermediaire, afin de s'approcher au mieux des niveaux de vitesses de deformation reellement rencontres au cours des operations de mise en forme. Le dispositif repose sur l'utilisation d'une machine d'essai servo-hydraulique comportant quatre verins independants et dont le mouvement permet la realisation d'essais de traction biaxiale sur eprouvettes cruciformes. La principale difficulte reside dans le choix de la forme de l'eprouvette cruciforme qui, a ce jour, n'est pas du tout standardisee. Pour notre application, il est necessaire d'observer l'apparition de la striction au centre de l'eprouvette afin de relier directement la valeur du chemin des deformations au centre a celle du rapport des vitesses des verins sur les deux axes perpendiculaires. Cette contrainte permet d'obtenir une courbe limite de formage (CLF) complete en faisant simplement varier le rapport des vitesses des verins sur les deux axes. Une telle eprouvette a ete optimisee et validee numeriquement, puis experimentalement. L'application d'une methode rigoureuse pour detecter l'apparition de la striction, associee a une mesure des deformations par correlation d'images obtenues a l'aide d'une camera rapide, permet de tracer experimentalement les CLF recherchees. La methode est validee pour un alliage d'aluminium 5086. L'identification des parametres constitutifs de la loi d'ecrouissage et du critere de plasticite est realisee par analyse inverse grâce a l'utilisation d'une mesure de champ locale.
ABSTRACT In hydrodynamic lubrication, the slip conditions have been studied previously from the m... more ABSTRACT In hydrodynamic lubrication, the slip conditions have been studied previously from the model of the slip length and the wall shear stress, but recently, in the literature on the slip at the interface fluid–solid, it has been shown that many questions will remain unsolved for long time to come. In fact, the modeling of the back-flow near the wall was not really taken into account. In this paper, we propose a more rigorous writing of the Reynolds equation (modified), taking into account the phenomena of slip and back-flow at wall. Subsequently, this equation is applied to the case of an inclined pad bearing and the results show that there is a significant influence of those phenomena on the operating characteristics.
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
This work is devoted to the application of the micromechanical Gurson-Tvergaard-Needleman (GTN) m... more This work is devoted to the application of the micromechanical Gurson-Tvergaard-Needleman (GTN) model to study the ductile tearing of 12NiCr6 steel. GTN model is widely used to describe the three stages of ductile tearing: nucleation, growth and the coalescence of micro-voids. A new approach based on the identification of the GTN damage model coupled or not with hardening laws using inverse analysis. After identification, the obtained results show a good agreement between the experimental curve tensile test of an axisymetric notched bar (AN2) and those numerically obtained for GTN model coupled with the hardening laws. In order to validate the identified GTN parameters, a simulation of tear test is conducted on 12 NiCr6 steel CT specimen. The numerical results are compared with experimental results found in the literature and a good agreement is obtained. This identification procedure is more accurate than when the damage parameters are identified independently of the hardening laws.
This work is devoted to the application of the micromechanical Gurson-Tvergaard-Needleman (GTN) m... more This work is devoted to the application of the micromechanical Gurson-Tvergaard-Needleman (GTN) model to study the ductile tearing of 12NiCr6 steel. GTN model is widely used to describe the three stages of ductile tearing: nucleation, growth and the coalescence of micro-voids. A new approach based on the identification of the GTN damage model coupled or not with hardening laws using inverse analysis. After identification, the obtained results show a good agreement between the experimental curve tensile test of an axisymetric notched bar (AN2) and those numerically obtained for GTN model coupled with the hardening laws. In order to validate the identified GTN parameters, a simulation of tear test is conducted on 12 NiCr6 steel CT specimen. The numerical results are compared with experimental results found in the literature and a good agreement is obtained. This identification procedure is more accurate than when the damage parameters are identified independently of the hardening laws. Citation: Hadj Miloud, M., Zidane, I., Mendas, M., Coupled identification of the hardening behavior laws and Gurson-Tvergaard-Needleman damage parameters-Validation on tear test of 12NiCr6 CT specimen, Frattura ed Integrità Strutturale, 49 (2019) 630-642.
L’utilisation de procedes de mise en forme de toles minces (emboutissage, hydroformage, formage i... more L’utilisation de procedes de mise en forme de toles minces (emboutissage, hydroformage, formage incremental, …) est tres repandue dans l’industrie. L’amelioration de la prediction des outils de simulation numerique passe par une identification precise de la loi de comportement et des limites de formabilite du materiau constituant la tole. Pour cela, il est souhaitable d’etudier le comportement des toles minces sous des etats de chargements proches de ceux rencontres dans le procede de mise en forme. A cet effet, l’essai de traction biaxial dans le plan de la tole a ete retenu parmi d’autres techniques de sollicitations biaxiales. Dans cette etude, un banc d’essais de traction biaxiale est developpe avec pour objectif d’identifier, a partir d’un meme essai rheologique, la loi de comportement et les limites de formabilite du materiau etudie sous sollicitations statiques ou dynamiques. Ce dispositif experimental est compose de quatre verins hydrauliques disposes horizontalement. La capacite de chaque verin est de 50kN, la vitesse de deplacement sur chaque axe peut atteindre 2m/s. Le pilotage permet d’imposer des rapports de biaxialite lineaires et non-lineaires. Ces essais biaxiaux sont realises sur une eprouvette plane dite « eprouvette cruciforme ». La geometrie optimale de celle-ci est definie a partir d’une etude parametrique realisee sur differentes formes d’eprouvettes cruciformes issues de la litterature. La difficulte principale dans la definition de cette geometrie est de s’assurer de l’apparition de la striction localisee au centre de l’eprouvette afin de maitriser le chemin de deformation impose par le deplacement des verins. Au cours de l’essai, la zone centrale de l’eprouvette est filmee et une technique de correlation d’image est ensuite utilisee en post-traitement pour obtenir le champ de deformation dans l’eprouvette. Par la suite, la procedure experimentale et la geometrie de l’eprouvette sont validees a partir d’une campagne d’essais realisee sur un alliage d’aluminium AA2017. Une procedure specifique de detection de l’apparition de la striction localisee pour cette forme d’eprouvette est definie. Une campagne experimentale est menee sur une tole en alliage d’aluminium AA5086. La courbe limite de formage (CLF) experimentale de cette tole est etablie a partir de la procedure definie precedemment. Enfin, les courbes forces/deplacements experimentales sont utilisees afin d’identifier une loi de comportement par methode inverse a partir d’un modele elements finis (EF) de l’essai biaxial. L’interet d’integrer une grandeur locale dans la procedure d’identification de la loi rheologique est presente. La loi de comportement identifiee est ensuite implementee dans le modele EF de l’essai de traction biaxial afin de determiner la CLF numerique du materiau etudie. Les CLF experimentale et numerique definies a partir de l’essai de traction biaxial sont comparees a celle obtenue sur le meme materiau par un dispositif d’essais de type Marciniak.
Journal of Materials Research and Technology, 2021
Abstract Lamellar cast irons are known as heterogeneous materials. Their overall hardness is dete... more Abstract Lamellar cast irons are known as heterogeneous materials. Their overall hardness is determined by the microhardness of their microstructure contents. This study pertains to extend the indentation size effect (ISE) analyses to these heterogeneous materials. Additionally to macrohardness tests, Vickers microindentation tests were carried out on two cast irons with fully pearlitic matrix. Tensile models for pearlitic steel with both Tabor's law and Taylor's model were introduced in the ISE analyses. Microhardness expressions of the pearlitic phase within these irons were thus obtained. The obtained expressions indicate that the tensile model and the concept of geometrically necessary dislocations (GNDs) can be used to predict the ISE of the pearlitic matrix. For this pearlitic phase, it is shown that the summation of the stresses, associated with the GNDs and SSDs, is more adequate than to consider only one work-hardening stress generated by the two types of dislocations density in the ISE study.
Purpose After more than a century of agreement with the postulate of non-slip condition (adhesion... more Purpose After more than a century of agreement with the postulate of non-slip condition (adhesion to the wall), the study of fluid-solid boundary conditions has shown renewed interest over the past two decades. Although numerous studies have not yet been arrived to a complete description of slip phenomena, however, it appears that the influence of wetting and/or surface roughness results in a weak interaction between fluid and solid; thus, the presence of the slip phenomenon is observed at the fluid-solid interface. The purpose of this paper is to highlight the presence of the slip phenomenon at the lubricated piston skirt-cylinder contact. Design/methodology/approach For this proposal, a modified Reynolds equation and operating characteristics are determined by taking into account the slip conditions at the interface between oil-film and entire cylinder surface. Findings The findings indicate that the operating characteristics are strongly influenced when the slip conditions are ta...
International Journal of Automotive and Mechanical Engineering, 2019
The piston material choice is a major factor in the design stages of internal combustion engines ... more The piston material choice is a major factor in the design stages of internal combustion engines for its importance to improving the durability and the operation reliability during the piston life cycle. Indeed, even as many researches have been conducted for a long time to improve the piston performances in the diesel engine, considerable numbers of piston damages still significantly occur. This research work is an assessment by the finite element method (FEM) of a set of piston materials for the purpose of being used in a direct injection diesel engine. The main objective is to predict stresses concentrations and the clearance between the piston and the cylinder (to avoid metal-metal adhesion) from thermomechanical solicitations. The stresses and deformations are evaluated in a 3D piston model by using ABAQUS software. A first assessment step is performed in heat convection/conduction modes to determine the temperature distribution. Then, this last one is coupled to the pressure f...
A two-dimensional finite element analysis has been performed to investigate hydromechanical and c... more A two-dimensional finite element analysis has been performed to investigate hydromechanical and conventional deep drawing processes. The effects of the fluid structure interaction on the material formability, the strain and the thickness distributions are investigated. Large plastic deformation is observed in the plank at the bottom and the corner of the punch. Plastic deformation distribution results show a difference between the hydromechanical deep drawing process and the conventional deep drawing which is due to the friction effect. This latter represents one of the major features of the hydromechanical deep drawing process. Concerning the formability of the blank, the obtained results show that the hydromechanical deep drawing process gives a better formability than the conventional deep drawing process.
Dans les procédés de mise en forme " classiques " de type emboutissage, la formabilité ... more Dans les procédés de mise en forme " classiques " de type emboutissage, la formabilité des matériaux est déterminée à partir des " courbes limites de formage " (CLF) obtenues à ce jour à partir d'essais statiques. Il apparaît aujourd'hui nécessaire de proposer de nouveaux moyens d'essais permettant de caractériser ces CLF dans des gammes de vitesses et de température adaptées aux nouveaux procédés de mise en forme actuellement développés dans l'industrie automobile ou aéronautique (hydroformage, formage incrémental, électrohydroformage, magnéto-formage, ...). Pour étudier la formabilité de tôles minces, des moyens d'essais dits " classique " sont actuellement disponibles (essai de Marciniak, essai de Nakazima, ...). Toutefois, ces dispositifs expérimentaux présentent un certain nombre d'inconvénients : l'étude de la formabilité est généralement dépendante des phénomènes de frottement se développant à l'interface éprouvett...
In innovative industrial processes such as hydroforming or incremental forming, strain rates up t... more In innovative industrial processes such as hydroforming or incremental forming, strain rates up to 500s-1 can be reached. As a result, experimental setups allowing to obtain large deformations from static to intermediate strain rate levels have to be developed to predict the formability limits of sheet metal materials. The proposed experimental device is a servo-hydraulic testing machine provided with four independent dynamic actuators allowing biaxial tensile tests on cruciform specimen. The main difficulty to define an appropriate cruciform specimen shape is to force the onset of necking in the central region. In this paper, different specimens used in previous studies are numerically investigated through FE simulations. A modified cruciform specimen shape is then proposed and the best set of geometrical dimensions is defined from a parametric study. Finally, the efficiency of the proposed specimen shape is validated by experiments. Numerical and experimental results, i.e., the strain level in the specimen and the onset of necking are compared and discussed to boundary conditions corresponding to an equi-biaxial tensile test.
Le recours a la simulation numerique, pour optimiser les differents procedes de mise en forme des... more Le recours a la simulation numerique, pour optimiser les differents procedes de mise en forme des toles metalliques, necessite une connaissance precise de leur comportement elasto-viscoplastique et de leur limite de formabilite. Le principal objectif de ce travail est de developper une nouvelle technique experimentale capable d'atteindre ces caracteristiques intrinseques du materiau, grâce a l'utilisation d'une geometrie d'eprouvette dediee. Ce dispositif doit etre capable de caracteriser le comportement des toles dans une gamme de vitesses allant du quasi-statique a l'intermediaire, afin de s'approcher au mieux des niveaux de vitesses de deformation reellement rencontres au cours des operations de mise en forme. Le dispositif repose sur l'utilisation d'une machine d'essai servo-hydraulique comportant quatre verins independants et dont le mouvement permet la realisation d'essais de traction biaxiale sur eprouvettes cruciformes. La principale difficulte reside dans le choix de la forme de l'eprouvette cruciforme qui, a ce jour, n'est pas du tout standardisee. Pour notre application, il est necessaire d'observer l'apparition de la striction au centre de l'eprouvette afin de relier directement la valeur du chemin des deformations au centre a celle du rapport des vitesses des verins sur les deux axes perpendiculaires. Cette contrainte permet d'obtenir une courbe limite de formage (CLF) complete en faisant simplement varier le rapport des vitesses des verins sur les deux axes. Une telle eprouvette a ete optimisee et validee numeriquement, puis experimentalement. L'application d'une methode rigoureuse pour detecter l'apparition de la striction, associee a une mesure des deformations par correlation d'images obtenues a l'aide d'une camera rapide, permet de tracer experimentalement les CLF recherchees. La methode est validee pour un alliage d'aluminium 5086. L'identification des parametres constitutifs de la loi d'ecrouissage et du critere de plasticite est realisee par analyse inverse grâce a l'utilisation d'une mesure de champ locale.
ABSTRACT In hydrodynamic lubrication, the slip conditions have been studied previously from the m... more ABSTRACT In hydrodynamic lubrication, the slip conditions have been studied previously from the model of the slip length and the wall shear stress, but recently, in the literature on the slip at the interface fluid–solid, it has been shown that many questions will remain unsolved for long time to come. In fact, the modeling of the back-flow near the wall was not really taken into account. In this paper, we propose a more rigorous writing of the Reynolds equation (modified), taking into account the phenomena of slip and back-flow at wall. Subsequently, this equation is applied to the case of an inclined pad bearing and the results show that there is a significant influence of those phenomena on the operating characteristics.
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
This work is devoted to the application of the micromechanical Gurson-Tvergaard-Needleman (GTN) m... more This work is devoted to the application of the micromechanical Gurson-Tvergaard-Needleman (GTN) model to study the ductile tearing of 12NiCr6 steel. GTN model is widely used to describe the three stages of ductile tearing: nucleation, growth and the coalescence of micro-voids. A new approach based on the identification of the GTN damage model coupled or not with hardening laws using inverse analysis. After identification, the obtained results show a good agreement between the experimental curve tensile test of an axisymetric notched bar (AN2) and those numerically obtained for GTN model coupled with the hardening laws. In order to validate the identified GTN parameters, a simulation of tear test is conducted on 12 NiCr6 steel CT specimen. The numerical results are compared with experimental results found in the literature and a good agreement is obtained. This identification procedure is more accurate than when the damage parameters are identified independently of the hardening laws.
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2019 by Ibrahim Zidane
Papers by Ibrahim Zidane