Ce livre est dédié à l'identification des paramètres de lois de comportement élastoplastiques ani... more Ce livre est dédié à l'identification des paramètres de lois de comportement élastoplastiques anisotropes en vue de leur utilisation pour la simulation numérique du procédé d'emboutissage de tôles métalliques. Les stratégies d'identification inverse sont basées sur les réponses d'essais expérimentaux inhomogènes et sur le couplage d'une méthode d'optimisation et de la simulation numérique par éléments finis pour coïncider la réponse calculée par le modèle de comportement et la réponse expérimentale correspondante. Les paramètres identifiés sont les coefficients d'anisotropie et les paramètres d'écrouissage pour différentes lois de comportement. Dans ces modèles élastoplastiques anisotropes, l'écrouissage est isotrope et les potentiels plastiques associé et non associé sont considérés. Dans cette identification, les essais de traction simple hors-axes et l'essai de traction plane inhomogène sont utilisés. Une Technique spécifique d'analyse de sensibilité paramétrique est developpée pour analyser l'influence de la variation des paramètres de comportement identifiés sur la réponse des essais. Cette technique est mise en oeuvre sur des exemples pratiques.
The identification of welded tubes properties considering the weld bead and Heat Affected Zone (H... more The identification of welded tubes properties considering the weld bead and Heat Affected Zone (HAZ) is important for reliable and accurate finite element simulation of tubular plastic forming processes such as tube hydroforming and rotary draw bending processes. Therefore, a simplified method is proposed to extract the weld bead and HAZ properties. Full size standard tensile specimens cut from the welded tube and comprising the weld parallel to the load direction are extended to failure. Mechanical properties obtained from uniaxial tensile test are correlated with the microhardness data measured across the welded specimen and by using the rule of mixtures; the constitutive model parameters of weld bead and HAZ regions are identified. Accuracy of the proposed method is assessed by comparing finite element simulation predictions to experimental measurements obtained from two mechanical tests: the first one is the uniaxial tensile test performed on specimens comprising the weld line perpendicular to the loading direction and the second test is the free bulge hydroforming test achieved on seamed tubular samples. This investigation has shown that the presented method is practical in use and sufficiently accurate to extract the weld metal properties of seamed tubes."
The objective of this study is the validation of an inverse identification method using tube
hy... more The objective of this study is the validation of an inverse identification method using tube
hydroforming in square cross-section die. This work is divided in two steps: Firstly, a hybrid
experimental-numerical method using free bulge tests and a suitable finite element model were
developed to identify tubular material parameters. Secondly, tubular samples were hydroformed
against square-cross sectional die. The tests were carried out by means of a new home-designed and
manufactured bulge forming machine. Two kind of tubes made of low carbon steel S235 and
aluminum alloy AA6063-O are hydroformed. Finite element model was build to validate the inverse
identification procedure for both materials, experimental thicknesses along the profile of cross
sectional hydroformed parts are measured and compared with the numerical ones. It was proven by
analyzing the obtained results that the tube thickness distribution along the profile in the square
cross-sectional die hydroforming is sensitive to the identified material parameters. It was shown a
good correlation between experimental measurement and predicted results.
"This paper deals with an inverse approach strategy to determine the constitutive parameters of t... more "This paper deals with an inverse approach strategy to determine the constitutive parameters of tubular
materials made of low carbon steel S235 and aluminum alloy AA6063-O. For this purpose, a new selfdesigned
bulge forming machine is manufactured to perform tubular bulge tests. Additionally, tensile
tests are carried out on specimens cut from the tube to measure the Lankford anisotropy coefficients.
The proposed inverse identification method is developed to identify efficiently the flow stress parameters
considering material anisotropy effects. This method is made up of an optimization algorithm that connects
experimental free bulge test results and finite element analysis. The comparison between predicted
results and experimental data is performed to assess the proposed approach. It is shown that this identification
strategy provides appropriate flow stress relationship which can be used to predict accurate
plastic deformation behavior during the tube hydroforming process.
2013 Elsevier Ltd. All rights reserved."
"The objective of this paper is to determine the behaviour parameters
of hydroformed tubular mat... more "The objective of this paper is to determine the behaviour parameters
of hydroformed tubular materials of annealed 25CrMo4 steel seamless tubes.
An inverse identification procedure has been developed to determine the flow
stress parameters from experimental free bulge and simple tensile tests. Two
inverse identification strategies are proposed. In the first one, the tubular
material behaviour is assumed isotropic, and then the parameters of the
effective stress-strain relationship are derived from experimental bulge height
versus the forming pressure. In the second one, the planar anisotropy of Hill’48
yield criterion is considered. Firstly, the simple tensile test is used to fit the
isotropic strain hardening law. Secondly, the anisotropic parameter is identified
by inverse technique from the experimental bulge test. The obtained results are
compared with experimental measurements to validate the proposed strategies.
It is proven that inverse identification methods could be a better alternative to
analytical methods for flow stress parameters determination. Moreover, the
anisotropy parameter has shown a large effect on the hydroformed tube
responses, particularly on the wall thickness. Consequently, this material
anisotropy should be considered within the flow stress identification of tube
bulge tests."
The paper describes a new method for the identification of the flow stress curves of anisotropic ... more The paper describes a new method for the identification of the flow stress curves of anisotropic sheet metals using a hydraulic bulge tests through circular and elliptical dies. This method is based on analytical model using the membrane equilibrium equation and experimental data involving the measurement of only polar deflection and applied hydraulic pressure. Four hydraulic bulge tests are used for the identification of flow stress parameters and anisotropy coefficients of Hill48 yield criterion. A sensitivity analysis of material parameters is carried out by FEA of hydraulic bulge tests. This identification procedure is applied on low carbon steel DC04 used for sheet metal forming. The obtained results are used for numerical simulation of plane tensile test to validation the proposed method. It is shown a good agreement between predicted and experimental results.
Dans ce papier, nous proposons une méthode pour la caractérisation du comportement mécanique des ... more Dans ce papier, nous proposons une méthode pour la caractérisation du comportement mécanique des joints soudés par induction à haute fréquence pour des
tubes ronds en acier doux S235JR. Cette technique de caractérisation est basée sur la réponse à la traction simple des éprouvettes comportant le cordon de soudure, sur des
mesures de microdureté et sur la règle des mélanges. Les paramètres du comportement du cordon de soudure et de la zone affectée thermiquement sont obtenus en identifiant la
réponse expérimentale de l’essai de traction simple de l’éprouvette soudée à l’expression du modèle d’écrouissage calculé par la règle des mélanges. La simulation
numérique par éléments finis permet d’évaluer la pertinence de l’approche proposée et de valider les hypothèses admises pour cette méthode. Les résultats numériques et
expérimentaux sont alors comparés. Les résultats obtenus montrent l’utilité et la performance de cette méthode pour déterminer le comportement plastique des tubes
soudés
Keywords:Tube Soudé, Zone Affectée Thermiquement, Règle des mélanges, Traction simple, Microdureté.
Nous proposons d’étudier l’effet des paramètres
d’écrouissage et d’anisotropie sur l’hydroformag... more Nous proposons d’étudier l’effet des paramètres
d’écrouissage et d’anisotropie sur l’hydroformage des tubes
minces en expansion libre par la méthode des éléments finis
(MEF). Les résultats obtenus montrent l’influence de ces
paramètres sur la hauteur et l’épaisseur au pôle en fonction de
la pression appliquée. Une analyse de sensibilité de la déformée
par rapport à ces paramètres révèle que la loi d’écrouissage
joue un rôle important dans le comportement des tubes hydroformés
Ce livre est dédié à l'identification des paramètres de lois de comportement élastoplastiques ani... more Ce livre est dédié à l'identification des paramètres de lois de comportement élastoplastiques anisotropes en vue de leur utilisation pour la simulation numérique du procédé d'emboutissage de tôles métalliques. Les stratégies d'identification inverse sont basées sur les réponses d'essais expérimentaux inhomogènes et sur le couplage d'une méthode d'optimisation et de la simulation numérique par éléments finis pour coïncider la réponse calculée par le modèle de comportement et la réponse expérimentale correspondante. Les paramètres identifiés sont les coefficients d'anisotropie et les paramètres d'écrouissage pour différentes lois de comportement. Dans ces modèles élastoplastiques anisotropes, l'écrouissage est isotrope et les potentiels plastiques associé et non associé sont considérés. Dans cette identification, les essais de traction simple hors-axes et l'essai de traction plane inhomogène sont utilisés. Une Technique spécifique d'analyse de sensibilité paramétrique est developpée pour analyser l'influence de la variation des paramètres de comportement identifiés sur la réponse des essais. Cette technique est mise en oeuvre sur des exemples pratiques.
The identification of welded tubes properties considering the weld bead and Heat Affected Zone (H... more The identification of welded tubes properties considering the weld bead and Heat Affected Zone (HAZ) is important for reliable and accurate finite element simulation of tubular plastic forming processes such as tube hydroforming and rotary draw bending processes. Therefore, a simplified method is proposed to extract the weld bead and HAZ properties. Full size standard tensile specimens cut from the welded tube and comprising the weld parallel to the load direction are extended to failure. Mechanical properties obtained from uniaxial tensile test are correlated with the microhardness data measured across the welded specimen and by using the rule of mixtures; the constitutive model parameters of weld bead and HAZ regions are identified. Accuracy of the proposed method is assessed by comparing finite element simulation predictions to experimental measurements obtained from two mechanical tests: the first one is the uniaxial tensile test performed on specimens comprising the weld line perpendicular to the loading direction and the second test is the free bulge hydroforming test achieved on seamed tubular samples. This investigation has shown that the presented method is practical in use and sufficiently accurate to extract the weld metal properties of seamed tubes."
The objective of this study is the validation of an inverse identification method using tube
hy... more The objective of this study is the validation of an inverse identification method using tube
hydroforming in square cross-section die. This work is divided in two steps: Firstly, a hybrid
experimental-numerical method using free bulge tests and a suitable finite element model were
developed to identify tubular material parameters. Secondly, tubular samples were hydroformed
against square-cross sectional die. The tests were carried out by means of a new home-designed and
manufactured bulge forming machine. Two kind of tubes made of low carbon steel S235 and
aluminum alloy AA6063-O are hydroformed. Finite element model was build to validate the inverse
identification procedure for both materials, experimental thicknesses along the profile of cross
sectional hydroformed parts are measured and compared with the numerical ones. It was proven by
analyzing the obtained results that the tube thickness distribution along the profile in the square
cross-sectional die hydroforming is sensitive to the identified material parameters. It was shown a
good correlation between experimental measurement and predicted results.
"This paper deals with an inverse approach strategy to determine the constitutive parameters of t... more "This paper deals with an inverse approach strategy to determine the constitutive parameters of tubular
materials made of low carbon steel S235 and aluminum alloy AA6063-O. For this purpose, a new selfdesigned
bulge forming machine is manufactured to perform tubular bulge tests. Additionally, tensile
tests are carried out on specimens cut from the tube to measure the Lankford anisotropy coefficients.
The proposed inverse identification method is developed to identify efficiently the flow stress parameters
considering material anisotropy effects. This method is made up of an optimization algorithm that connects
experimental free bulge test results and finite element analysis. The comparison between predicted
results and experimental data is performed to assess the proposed approach. It is shown that this identification
strategy provides appropriate flow stress relationship which can be used to predict accurate
plastic deformation behavior during the tube hydroforming process.
2013 Elsevier Ltd. All rights reserved."
"The objective of this paper is to determine the behaviour parameters
of hydroformed tubular mat... more "The objective of this paper is to determine the behaviour parameters
of hydroformed tubular materials of annealed 25CrMo4 steel seamless tubes.
An inverse identification procedure has been developed to determine the flow
stress parameters from experimental free bulge and simple tensile tests. Two
inverse identification strategies are proposed. In the first one, the tubular
material behaviour is assumed isotropic, and then the parameters of the
effective stress-strain relationship are derived from experimental bulge height
versus the forming pressure. In the second one, the planar anisotropy of Hill’48
yield criterion is considered. Firstly, the simple tensile test is used to fit the
isotropic strain hardening law. Secondly, the anisotropic parameter is identified
by inverse technique from the experimental bulge test. The obtained results are
compared with experimental measurements to validate the proposed strategies.
It is proven that inverse identification methods could be a better alternative to
analytical methods for flow stress parameters determination. Moreover, the
anisotropy parameter has shown a large effect on the hydroformed tube
responses, particularly on the wall thickness. Consequently, this material
anisotropy should be considered within the flow stress identification of tube
bulge tests."
The paper describes a new method for the identification of the flow stress curves of anisotropic ... more The paper describes a new method for the identification of the flow stress curves of anisotropic sheet metals using a hydraulic bulge tests through circular and elliptical dies. This method is based on analytical model using the membrane equilibrium equation and experimental data involving the measurement of only polar deflection and applied hydraulic pressure. Four hydraulic bulge tests are used for the identification of flow stress parameters and anisotropy coefficients of Hill48 yield criterion. A sensitivity analysis of material parameters is carried out by FEA of hydraulic bulge tests. This identification procedure is applied on low carbon steel DC04 used for sheet metal forming. The obtained results are used for numerical simulation of plane tensile test to validation the proposed method. It is shown a good agreement between predicted and experimental results.
Dans ce papier, nous proposons une méthode pour la caractérisation du comportement mécanique des ... more Dans ce papier, nous proposons une méthode pour la caractérisation du comportement mécanique des joints soudés par induction à haute fréquence pour des
tubes ronds en acier doux S235JR. Cette technique de caractérisation est basée sur la réponse à la traction simple des éprouvettes comportant le cordon de soudure, sur des
mesures de microdureté et sur la règle des mélanges. Les paramètres du comportement du cordon de soudure et de la zone affectée thermiquement sont obtenus en identifiant la
réponse expérimentale de l’essai de traction simple de l’éprouvette soudée à l’expression du modèle d’écrouissage calculé par la règle des mélanges. La simulation
numérique par éléments finis permet d’évaluer la pertinence de l’approche proposée et de valider les hypothèses admises pour cette méthode. Les résultats numériques et
expérimentaux sont alors comparés. Les résultats obtenus montrent l’utilité et la performance de cette méthode pour déterminer le comportement plastique des tubes
soudés
Keywords:Tube Soudé, Zone Affectée Thermiquement, Règle des mélanges, Traction simple, Microdureté.
Nous proposons d’étudier l’effet des paramètres
d’écrouissage et d’anisotropie sur l’hydroformag... more Nous proposons d’étudier l’effet des paramètres
d’écrouissage et d’anisotropie sur l’hydroformage des tubes
minces en expansion libre par la méthode des éléments finis
(MEF). Les résultats obtenus montrent l’influence de ces
paramètres sur la hauteur et l’épaisseur au pôle en fonction de
la pression appliquée. Une analyse de sensibilité de la déformée
par rapport à ces paramètres révèle que la loi d’écrouissage
joue un rôle important dans le comportement des tubes hydroformés
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hydroforming in square cross-section die. This work is divided in two steps: Firstly, a hybrid
experimental-numerical method using free bulge tests and a suitable finite element model were
developed to identify tubular material parameters. Secondly, tubular samples were hydroformed
against square-cross sectional die. The tests were carried out by means of a new home-designed and
manufactured bulge forming machine. Two kind of tubes made of low carbon steel S235 and
aluminum alloy AA6063-O are hydroformed. Finite element model was build to validate the inverse
identification procedure for both materials, experimental thicknesses along the profile of cross
sectional hydroformed parts are measured and compared with the numerical ones. It was proven by
analyzing the obtained results that the tube thickness distribution along the profile in the square
cross-sectional die hydroforming is sensitive to the identified material parameters. It was shown a
good correlation between experimental measurement and predicted results.
materials made of low carbon steel S235 and aluminum alloy AA6063-O. For this purpose, a new selfdesigned
bulge forming machine is manufactured to perform tubular bulge tests. Additionally, tensile
tests are carried out on specimens cut from the tube to measure the Lankford anisotropy coefficients.
The proposed inverse identification method is developed to identify efficiently the flow stress parameters
considering material anisotropy effects. This method is made up of an optimization algorithm that connects
experimental free bulge test results and finite element analysis. The comparison between predicted
results and experimental data is performed to assess the proposed approach. It is shown that this identification
strategy provides appropriate flow stress relationship which can be used to predict accurate
plastic deformation behavior during the tube hydroforming process.
2013 Elsevier Ltd. All rights reserved."
of hydroformed tubular materials of annealed 25CrMo4 steel seamless tubes.
An inverse identification procedure has been developed to determine the flow
stress parameters from experimental free bulge and simple tensile tests. Two
inverse identification strategies are proposed. In the first one, the tubular
material behaviour is assumed isotropic, and then the parameters of the
effective stress-strain relationship are derived from experimental bulge height
versus the forming pressure. In the second one, the planar anisotropy of Hill’48
yield criterion is considered. Firstly, the simple tensile test is used to fit the
isotropic strain hardening law. Secondly, the anisotropic parameter is identified
by inverse technique from the experimental bulge test. The obtained results are
compared with experimental measurements to validate the proposed strategies.
It is proven that inverse identification methods could be a better alternative to
analytical methods for flow stress parameters determination. Moreover, the
anisotropy parameter has shown a large effect on the hydroformed tube
responses, particularly on the wall thickness. Consequently, this material
anisotropy should be considered within the flow stress identification of tube
bulge tests."
Talks
tubes ronds en acier doux S235JR. Cette technique de caractérisation est basée sur la réponse à la traction simple des éprouvettes comportant le cordon de soudure, sur des
mesures de microdureté et sur la règle des mélanges. Les paramètres du comportement du cordon de soudure et de la zone affectée thermiquement sont obtenus en identifiant la
réponse expérimentale de l’essai de traction simple de l’éprouvette soudée à l’expression du modèle d’écrouissage calculé par la règle des mélanges. La simulation
numérique par éléments finis permet d’évaluer la pertinence de l’approche proposée et de valider les hypothèses admises pour cette méthode. Les résultats numériques et
expérimentaux sont alors comparés. Les résultats obtenus montrent l’utilité et la performance de cette méthode pour déterminer le comportement plastique des tubes
soudés
Keywords:Tube Soudé, Zone Affectée Thermiquement, Règle des mélanges, Traction simple, Microdureté.
d’écrouissage et d’anisotropie sur l’hydroformage des tubes
minces en expansion libre par la méthode des éléments finis
(MEF). Les résultats obtenus montrent l’influence de ces
paramètres sur la hauteur et l’épaisseur au pôle en fonction de
la pression appliquée. Une analyse de sensibilité de la déformée
par rapport à ces paramètres révèle que la loi d’écrouissage
joue un rôle important dans le comportement des tubes hydroformés
Teaching Documents
hydroforming in square cross-section die. This work is divided in two steps: Firstly, a hybrid
experimental-numerical method using free bulge tests and a suitable finite element model were
developed to identify tubular material parameters. Secondly, tubular samples were hydroformed
against square-cross sectional die. The tests were carried out by means of a new home-designed and
manufactured bulge forming machine. Two kind of tubes made of low carbon steel S235 and
aluminum alloy AA6063-O are hydroformed. Finite element model was build to validate the inverse
identification procedure for both materials, experimental thicknesses along the profile of cross
sectional hydroformed parts are measured and compared with the numerical ones. It was proven by
analyzing the obtained results that the tube thickness distribution along the profile in the square
cross-sectional die hydroforming is sensitive to the identified material parameters. It was shown a
good correlation between experimental measurement and predicted results.
materials made of low carbon steel S235 and aluminum alloy AA6063-O. For this purpose, a new selfdesigned
bulge forming machine is manufactured to perform tubular bulge tests. Additionally, tensile
tests are carried out on specimens cut from the tube to measure the Lankford anisotropy coefficients.
The proposed inverse identification method is developed to identify efficiently the flow stress parameters
considering material anisotropy effects. This method is made up of an optimization algorithm that connects
experimental free bulge test results and finite element analysis. The comparison between predicted
results and experimental data is performed to assess the proposed approach. It is shown that this identification
strategy provides appropriate flow stress relationship which can be used to predict accurate
plastic deformation behavior during the tube hydroforming process.
2013 Elsevier Ltd. All rights reserved."
of hydroformed tubular materials of annealed 25CrMo4 steel seamless tubes.
An inverse identification procedure has been developed to determine the flow
stress parameters from experimental free bulge and simple tensile tests. Two
inverse identification strategies are proposed. In the first one, the tubular
material behaviour is assumed isotropic, and then the parameters of the
effective stress-strain relationship are derived from experimental bulge height
versus the forming pressure. In the second one, the planar anisotropy of Hill’48
yield criterion is considered. Firstly, the simple tensile test is used to fit the
isotropic strain hardening law. Secondly, the anisotropic parameter is identified
by inverse technique from the experimental bulge test. The obtained results are
compared with experimental measurements to validate the proposed strategies.
It is proven that inverse identification methods could be a better alternative to
analytical methods for flow stress parameters determination. Moreover, the
anisotropy parameter has shown a large effect on the hydroformed tube
responses, particularly on the wall thickness. Consequently, this material
anisotropy should be considered within the flow stress identification of tube
bulge tests."
tubes ronds en acier doux S235JR. Cette technique de caractérisation est basée sur la réponse à la traction simple des éprouvettes comportant le cordon de soudure, sur des
mesures de microdureté et sur la règle des mélanges. Les paramètres du comportement du cordon de soudure et de la zone affectée thermiquement sont obtenus en identifiant la
réponse expérimentale de l’essai de traction simple de l’éprouvette soudée à l’expression du modèle d’écrouissage calculé par la règle des mélanges. La simulation
numérique par éléments finis permet d’évaluer la pertinence de l’approche proposée et de valider les hypothèses admises pour cette méthode. Les résultats numériques et
expérimentaux sont alors comparés. Les résultats obtenus montrent l’utilité et la performance de cette méthode pour déterminer le comportement plastique des tubes
soudés
Keywords:Tube Soudé, Zone Affectée Thermiquement, Règle des mélanges, Traction simple, Microdureté.
d’écrouissage et d’anisotropie sur l’hydroformage des tubes
minces en expansion libre par la méthode des éléments finis
(MEF). Les résultats obtenus montrent l’influence de ces
paramètres sur la hauteur et l’épaisseur au pôle en fonction de
la pression appliquée. Une analyse de sensibilité de la déformée
par rapport à ces paramètres révèle que la loi d’écrouissage
joue un rôle important dans le comportement des tubes hydroformés