https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sun, 14 Jun 2026 03:15:46 GMT 2026-06-14T03:15:46Z http://hdl.handle.net/10985/9478 Procédé élaboration d'un alliage de titane, alliage et prothèse ainsi obtenus LAHEURTE, Pascal; PRIMA, Frederic; GLORIANT, Thierry; ELMAY, Wafa; EBERHARDT, André; PATOOR, Etienne Selon un procédé de traitement thermomécanique d'un alliage de titane comportant entre 23 et 27% de niobium en proportion atomique, entre 0 et 10% de zirconium, et entre 0 et 1% d'oxygène, d'azote et/ou de silicium, on procède aux étapes suivantes : a) une montée d'un échantillon de l'alliage à une température supérieure à 900°C ; b) une trempe rapide ; c) une déformation à froid sévère ; d) un traitement de vieillissement à une température comprise entre 200 et 600°C, la durée du traitement de vieillissement étant comprise entre 10 secondes et 10 minutes. Alliage obtenu par ce procédé et prothèses réalisées dans un tel alliage. Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10985/9478 2014-01-01T00:00:00Z LAHEURTE, Pascal PRIMA, Frederic GLORIANT, Thierry ELMAY, Wafa EBERHARDT, André PATOOR, Etienne Selon un procédé de traitement thermomécanique d'un alliage de titane comportant entre 23 et 27% de niobium en proportion atomique, entre 0 et 10% de zirconium, et entre 0 et 1% d'oxygène, d'azote et/ou de silicium, on procède aux étapes suivantes : a) une montée d'un échantillon de l'alliage à une température supérieure à 900°C ; b) une trempe rapide ; c) une déformation à froid sévère ; d) un traitement de vieillissement à une température comprise entre 200 et 600°C, la durée du traitement de vieillissement étant comprise entre 10 secondes et 10 minutes. Alliage obtenu par ce procédé et prothèses réalisées dans un tel alliage. http://hdl.handle.net/10985/7800 Estimation of the electron beam-induced specimen heating and the emitted X-rays spatial resolution by Kossel microdiffraction in a scanning electron microscope BOUSCAUD, Denis; PATOOR, Etienne; BERVEILLER, Sophie; PESCI, Raphaël A Kossel microdiffraction experimental setup has been developed inside a Scanning Electron Micro-scope for crystallographic orientation, strain and stress determination at a micrometer scale. This paper reports an estimation of copper and germanium specimens heating due to the electron beam bombardment. The temperature rise is calculated from precise lattice parameters measurement considering different currents induced in the specimens. The spatial resolution of the technique is then deduced. Lien vers la version éditeur: http://www.sciencedirect.com/science/article/pii/S0304399112000307 Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/7800 2012-01-01T00:00:00Z BOUSCAUD, Denis PATOOR, Etienne BERVEILLER, Sophie PESCI, Raphaël A Kossel microdiffraction experimental setup has been developed inside a Scanning Electron Micro-scope for crystallographic orientation, strain and stress determination at a micrometer scale. This paper reports an estimation of copper and germanium specimens heating due to the electron beam bombardment. The temperature rise is calculated from precise lattice parameters measurement considering different currents induced in the specimens. The spatial resolution of the technique is then deduced. http://hdl.handle.net/10985/8513 Application of Laguerre based adaptive predictive control to Shape Memory Alloy (SMA) actuators KANNAN, S.; PATOOR, Etienne; GIRAUD-AUDINE, Christophe This paper discusses the use of an existing adaptive predictive controller to control some Shape Memory Alloy (SMA) linear actuators. The model consists in a truncated linear combination of Laguerre filters identified online. The controller stability is studied in details. It is proven that the tracking error is asymptotically stable under some conditions on the modelling error. Moreover, the tracking error converge toward zero for step references, even if the identified model is inaccurate. Experimentalcresults obtained on two different kind of actuator validate the proposed control. They also show that it is robust with regard to input constraints. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/8513 2013-01-01T00:00:00Z KANNAN, S. PATOOR, Etienne GIRAUD-AUDINE, Christophe This paper discusses the use of an existing adaptive predictive controller to control some Shape Memory Alloy (SMA) linear actuators. The model consists in a truncated linear combination of Laguerre filters identified online. The controller stability is studied in details. It is proven that the tracking error is asymptotically stable under some conditions on the modelling error. Moreover, the tracking error converge toward zero for step references, even if the identified model is inaccurate. Experimentalcresults obtained on two different kind of actuator validate the proposed control. They also show that it is robust with regard to input constraints. http://hdl.handle.net/10985/10100 A finite-element based numerical tool for Ni47Ti44Nb9 SMA structures design application to tightening rings PIOTROWSKI, Boris; BEN ZINEB, Tarak; EBERHARDT, André; PATOOR, Etienne This paper deals with the design of Ni47Ti44Nb9 Shape Memory Alloy (SMA) tightening components. The tightening of an SMA ring on an elastic pipe is analyzed using the finite element code ABAQUS® and a UMAT subroutine developed in our group to model the specific behavior of Ni47Ti44Nb9 SMA. Main features of the thermomechanical model implemented in this UMAT routine are briefly recalled. Numerical predictions are validated using experimental tightening pressures obtained on a test bed developed in this work. The validation strategy is documented and the results for different ring thicknesses are presented. This finite element tool is then applied to a parametric study of the influence of ridges on the tightening pressure. Eventually, geometrical defects like out of roundness are considered. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/10100 2012-01-01T00:00:00Z PIOTROWSKI, Boris BEN ZINEB, Tarak EBERHARDT, André PATOOR, Etienne This paper deals with the design of Ni47Ti44Nb9 Shape Memory Alloy (SMA) tightening components. The tightening of an SMA ring on an elastic pipe is analyzed using the finite element code ABAQUS® and a UMAT subroutine developed in our group to model the specific behavior of Ni47Ti44Nb9 SMA. Main features of the thermomechanical model implemented in this UMAT routine are briefly recalled. Numerical predictions are validated using experimental tightening pressures obtained on a test bed developed in this work. The validation strategy is documented and the results for different ring thicknesses are presented. This finite element tool is then applied to a parametric study of the influence of ridges on the tightening pressure. Eventually, geometrical defects like out of roundness are considered. http://hdl.handle.net/10985/10324 Inter- and Intragranular Stress Determination with Kossel Microdiffraction in a Scanning Electron Microscope INAL, Karim; PATOOR, Etienne; LECOMTE, Jean-Sébastien; EBERHARDT, André; BERVEILLER, Sophie; PESCI, Raphaël A Kossel microdiffraction experimental set up is under development inside a Scanning Electron Microscope (SEM) in order to determine the crystallographic orientation as well as the inter- and intragranular strains and stresses on the micron scale, using a one cubic micrometer spot. The experimental Kossel line patterns are obtained by way of a CCD camera and are then fully indexed using a home-made simulation program. The so-determined orientation is compared with Electron Back-Scattered Diffraction (EBSD) results, and in-situ tests are performed inside the SEM using a tensile/compressive machine. The aim is to verify a 50MPa stress sensitivity for this technique and to take advantage from this microscope environment to associate microstructure observations (slip lines, particle decohesion, crack initiation) with determined stress analyses. Sun, 01 Jan 2006 00:00:00 GMT http://hdl.handle.net/10985/10324 2006-01-01T00:00:00Z INAL, Karim PATOOR, Etienne LECOMTE, Jean-Sébastien EBERHARDT, André BERVEILLER, Sophie PESCI, Raphaël A Kossel microdiffraction experimental set up is under development inside a Scanning Electron Microscope (SEM) in order to determine the crystallographic orientation as well as the inter- and intragranular strains and stresses on the micron scale, using a one cubic micrometer spot. The experimental Kossel line patterns are obtained by way of a CCD camera and are then fully indexed using a home-made simulation program. The so-determined orientation is compared with Electron Back-Scattered Diffraction (EBSD) results, and in-situ tests are performed inside the SEM using a tensile/compressive machine. The aim is to verify a 50MPa stress sensitivity for this technique and to take advantage from this microscope environment to associate microstructure observations (slip lines, particle decohesion, crack initiation) with determined stress analyses. http://hdl.handle.net/10985/9869 Advances in martensitic transformations in Cu-based shape memory alloys achieved by in situ neutron and synchrotron X-ray diffraction methods MALARD, Benoît; SITTNER, Petr; PATOOR, Etienne; BERVEILLER, Sophie This article deals with the application of several X-ray and neutron diffraction methods to investigate the mechanics of a stress induced martensitic transformation in Cu-based shape memory alloy polycrystals. It puts experimental results obtained by two different research groups on different length scales into context with the mechanics of stress induced martensitic transformation in polycrystalline environment. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/9869 2012-01-01T00:00:00Z MALARD, Benoît SITTNER, Petr PATOOR, Etienne BERVEILLER, Sophie This article deals with the application of several X-ray and neutron diffraction methods to investigate the mechanics of a stress induced martensitic transformation in Cu-based shape memory alloy polycrystals. It puts experimental results obtained by two different research groups on different length scales into context with the mechanics of stress induced martensitic transformation in polycrystalline environment. http://hdl.handle.net/10985/10575 Identification and interpretation of material parameters of a shape memory alloy (SMA) model PIOTROWSKI, Boris; CHEMISKY, Yves; MERAGHNI, Fodil; ECHCHORFI, Rachid; BOURGEOIS, Nadine; PATOOR, Etienne The thermomechanical behavior of Shape Memory Alloys (SMAs) is described by many micromechanical and phenomenological models. The first ones have material parameters whose physical meaning is based on the crystallography of the phase transformation related to the studied alloy. In contrast, phenomenological models often have material parameters whose physical meaning is not obvious and that makes them difficult to identify, some of which are based on mathematical considerations. In this paper, we propose to use the formulation of the phenomenological model of Chemisky et al., and to consider the particular case of a superelastic SMA. In this case, the constitutive equation should be easily expressed analytically through the strain tensor as a function of applied load direction and material parameters. The behavior is then characterized by a complete and proportional loading. This analytical model contains 7 material parameters, 1 related to the elasticity and 6 to the phase transformation. Based on several isothermal tensile tests at various temperatures, material parameters of this model are identified using the Levenberg-Marquardt algorithm and an analytical calculation of the sensitivity matrix. Their physical meaning and their influence on the thermomechanical behavior of the studied alloy are highlighted and discussed. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/10575 2013-01-01T00:00:00Z PIOTROWSKI, Boris CHEMISKY, Yves MERAGHNI, Fodil ECHCHORFI, Rachid BOURGEOIS, Nadine PATOOR, Etienne The thermomechanical behavior of Shape Memory Alloys (SMAs) is described by many micromechanical and phenomenological models. The first ones have material parameters whose physical meaning is based on the crystallography of the phase transformation related to the studied alloy. In contrast, phenomenological models often have material parameters whose physical meaning is not obvious and that makes them difficult to identify, some of which are based on mathematical considerations. In this paper, we propose to use the formulation of the phenomenological model of Chemisky et al., and to consider the particular case of a superelastic SMA. In this case, the constitutive equation should be easily expressed analytically through the strain tensor as a function of applied load direction and material parameters. The behavior is then characterized by a complete and proportional loading. This analytical model contains 7 material parameters, 1 related to the elasticity and 6 to the phase transformation. Based on several isothermal tensile tests at various temperatures, material parameters of this model are identified using the Levenberg-Marquardt algorithm and an analytical calculation of the sensitivity matrix. Their physical meaning and their influence on the thermomechanical behavior of the studied alloy are highlighted and discussed. http://hdl.handle.net/10985/10837 Identification of Model Parameter for the Simulation of SMA Structures Using Full Field Measurements CHEMISKY, Yves; MERAGHNI, Fodil; BOURGEOIS, Nadine; CORNELL, Stephen; ECHCHORFI, Rachid; PATOOR, Etienne With the design of new devices with complex geometry and to take advantage of their large recoverable strains, shape memory alloys components (SMA) are increasingly subjected to multiaxial loadings. The development process of SMA devices requires the prediction of their thermomechanical response, where the calibration of the material parameters for the numerical model is an important step. In this work, the parameters of a phenomenological model are extracted from multiaxial and heterogeneous tests carried out on specimens with the same thermomechanical loading history. Finite element analysis enables the computation of numerical strain fields using a thermodynamical constitutive model for shape memory alloys previously implemented in a finite element code. The strain fields computed numerically are compared with experimental ones obtained by DIC to find the model parameters which best matches experimental measurements using a newly developed parallelized mixed genetic/gradient-based optimization algorithm. These numerical simulations are carried out in parallel in a supercomputer to reduce the time necessary to identify the set of identified parameters. The major features of this new algorithm is its ability to identify material parameters of the thermomechanical behavior of shape memory alloys from full-field measurements for various loading conditions (different temperatures, multiaxial behavior, heterogeneous test configurations). It is demonstrated that model parameters for the simulation of SMA structures are thus obtained based on a reduced number of heterogeneous tests at different temperatures. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10837 2015-01-01T00:00:00Z CHEMISKY, Yves MERAGHNI, Fodil BOURGEOIS, Nadine CORNELL, Stephen ECHCHORFI, Rachid PATOOR, Etienne With the design of new devices with complex geometry and to take advantage of their large recoverable strains, shape memory alloys components (SMA) are increasingly subjected to multiaxial loadings. The development process of SMA devices requires the prediction of their thermomechanical response, where the calibration of the material parameters for the numerical model is an important step. In this work, the parameters of a phenomenological model are extracted from multiaxial and heterogeneous tests carried out on specimens with the same thermomechanical loading history. Finite element analysis enables the computation of numerical strain fields using a thermodynamical constitutive model for shape memory alloys previously implemented in a finite element code. The strain fields computed numerically are compared with experimental ones obtained by DIC to find the model parameters which best matches experimental measurements using a newly developed parallelized mixed genetic/gradient-based optimization algorithm. These numerical simulations are carried out in parallel in a supercomputer to reduce the time necessary to identify the set of identified parameters. The major features of this new algorithm is its ability to identify material parameters of the thermomechanical behavior of shape memory alloys from full-field measurements for various loading conditions (different temperatures, multiaxial behavior, heterogeneous test configurations). It is demonstrated that model parameters for the simulation of SMA structures are thus obtained based on a reduced number of heterogeneous tests at different temperatures. http://hdl.handle.net/10985/9969 Analysis of the deformation paths and thermomechanical parameter identification of a shape memory alloy using digital image correlation over heterogeneous tests CHEMISKY, Yves; MERAGHNI, Fodil; BOURGEOIS, Nadine; CORNELL, Stephen; ECHCHORFI, Rachid; PATOOR, Etienne With the design of new devices with complex geometry and to take advantage of their large recoverable strains, shape memory alloys components (SMA) are increasingly subjected to multiaxial loadings. The development process of SMA devices requires the prediction of their thermomechanical response, for which the calibration of the material parameters for the numerical model is an important step. In this work, the parameters of a phenomenological model are extracted from tests performed on specimens with non-uniform geometry, which induce heterogeneous strain fields carried out on specimens with the same thermomechanical loading history. The digital image correlation technique is employed to measure the strain fields on the surface of the specimen and to analyze the strain paths of chosen points. Finite element analysis enables the computation of numerical strain fields using a thermodynamical constitutive model for shape memory alloys previously implemented in a finite element code. The strain fields computed numerically are compared with experimental ones obtained by DIC to find the model parameters which best match experimental measurements using a newly developed parallelized mixed genetic/gradient-based optimization algorithm. These numerical simulations are carried out in parallel using a supercomputer to reduce the time necessary to identify the set of model parameters. The major features of this new algorithm is its ability to identify the material parameters which describe the thermomechanical behavior of shape memory alloys from full-field measurements for various loading conditions (different temperatures, multiaxial behavior, heterogeneous test configurations). It is demonstrated that model parameters for the simulation of SMA structures are thus obtained based on a reduced number of heterogeneous tests at different temperatures. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/9969 2015-01-01T00:00:00Z CHEMISKY, Yves MERAGHNI, Fodil BOURGEOIS, Nadine CORNELL, Stephen ECHCHORFI, Rachid PATOOR, Etienne With the design of new devices with complex geometry and to take advantage of their large recoverable strains, shape memory alloys components (SMA) are increasingly subjected to multiaxial loadings. The development process of SMA devices requires the prediction of their thermomechanical response, for which the calibration of the material parameters for the numerical model is an important step. In this work, the parameters of a phenomenological model are extracted from tests performed on specimens with non-uniform geometry, which induce heterogeneous strain fields carried out on specimens with the same thermomechanical loading history. The digital image correlation technique is employed to measure the strain fields on the surface of the specimen and to analyze the strain paths of chosen points. Finite element analysis enables the computation of numerical strain fields using a thermodynamical constitutive model for shape memory alloys previously implemented in a finite element code. The strain fields computed numerically are compared with experimental ones obtained by DIC to find the model parameters which best match experimental measurements using a newly developed parallelized mixed genetic/gradient-based optimization algorithm. These numerical simulations are carried out in parallel using a supercomputer to reduce the time necessary to identify the set of model parameters. The major features of this new algorithm is its ability to identify the material parameters which describe the thermomechanical behavior of shape memory alloys from full-field measurements for various loading conditions (different temperatures, multiaxial behavior, heterogeneous test configurations). It is demonstrated that model parameters for the simulation of SMA structures are thus obtained based on a reduced number of heterogeneous tests at different temperatures. http://hdl.handle.net/10985/9970 Phase Transformation of Anisotropic Shape Memory Alloys: Theory and Validation in Superelasticity CHATZIATHANASIOU, Dimitris; CHEMISKY, Yves; MERAGHNI, Fodil; CHATZIGEORGIOU, George; PATOOR, Etienne In the present study, a new transformation criterion that includes the effect of tension–compression asymmetry and texture-induced anisotropy is proposed and combined with a thermodynamical model to describe the thermomechanical behavior of polycrystalline shape memory alloys. An altered Prager criterion has been developed, introducing a general transformation of the axes in the stress space. A convexity analysis of such criterion is included along with an identification strategy aimed at extracting the model parameters related to tension–compression asymmetry and anisotropy. These are identified from a numerical simulation of an SMA polycrystal, using a self-consistent micromechanical model previously developed by Patoor et al. (J Phys IV 6(C1):277–292, 1996) for several loading cases on isotropic, rolled, and drawn textures. Transformation surfaces in the stress and transformation strain spaces are obtained and compared with those predicted by the micromechanical model. The good agreement obtained between the macroscopic and the microscopic polycrystalline simulations states that the proposed criterion and transformation strain evolution equation can capture phenomenologically the effects of texture on anisotropy and asymmetry in SMAs. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/9970 2015-01-01T00:00:00Z CHATZIATHANASIOU, Dimitris CHEMISKY, Yves MERAGHNI, Fodil CHATZIGEORGIOU, George PATOOR, Etienne In the present study, a new transformation criterion that includes the effect of tension–compression asymmetry and texture-induced anisotropy is proposed and combined with a thermodynamical model to describe the thermomechanical behavior of polycrystalline shape memory alloys. An altered Prager criterion has been developed, introducing a general transformation of the axes in the stress space. A convexity analysis of such criterion is included along with an identification strategy aimed at extracting the model parameters related to tension–compression asymmetry and anisotropy. These are identified from a numerical simulation of an SMA polycrystal, using a self-consistent micromechanical model previously developed by Patoor et al. (J Phys IV 6(C1):277–292, 1996) for several loading cases on isotropic, rolled, and drawn textures. Transformation surfaces in the stress and transformation strain spaces are obtained and compared with those predicted by the micromechanical model. The good agreement obtained between the macroscopic and the microscopic polycrystalline simulations states that the proposed criterion and transformation strain evolution equation can capture phenomenologically the effects of texture on anisotropy and asymmetry in SMAs.