References of "Gilles, Gaëtan"
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See detailStudy of phase transformations within bimetallic rolling mills
Neira Torres, Ingrid ULg; Lecomte-Beckers, Jacqueline ULg; Tchuindjang, Jérôme Tchoufack ULg et al

Scientific conference (2013, September 10)

With the aim of simulating the cooling behavior after a re-austenitizing stage of bimetallic rolling mills, both materials corresponding to spheroidal graphite iron (core material) and high chrome steel ... [more ▼]

With the aim of simulating the cooling behavior after a re-austenitizing stage of bimetallic rolling mills, both materials corresponding to spheroidal graphite iron (core material) and high chrome steel (shell material) must be characterized through thermo physical and mechanical tests as well as microscopic observations. Dilatometer tests were carried out for both materials in order to determinate thermo physical properties such as thermal expansion coefficient and density. Compression tests were also performed in order to estimate the effect of mechanical stress on martensite phase transformation, especially the nature and the type of martensite and start of transformation temperature. However there are some parameters that are still unknown and that are highly difficult to determinate. Inverse simulations are performed through Lagamine code with the aim of finding an estimated value for these parameters or improved parameters, more accurate than the ones already estimated. [less ▲]

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See detailQUASI-STATIC MECHANICAL BEHAVIOUR OF TI-6AL-4V ALLOY AT ROOM TEMPERATURE
Tuninetti Vásquez, Victor ULg; Gilles, Gaëtan ULg; Milis, Olivier ULg et al

in Complas XII (2013), XII

In order to determine the mechanical behavior of a bulk TA6V alloy, a set of mechanical tests such as shear, compression, tensile monotonic tests, and tensile tests on notched samples are performed. The ... [more ▼]

In order to determine the mechanical behavior of a bulk TA6V alloy, a set of mechanical tests such as shear, compression, tensile monotonic tests, and tensile tests on notched samples are performed. The material is tested at constant strain rate. Full-field optical technique for displacement measurements and strain computation are used for all the experiments. Plastic anisotropy and tension–compression asymmetry are observed. The CPB06 [1] yield criterion adapted for hexagonal close packed (hcp) material is identified. The sensitivity of the material parameters on the identification method as well as the efficiency of the model to predict forces and displacement field are discussed. Validation is done by using Finite Element method (FEM) simulations and 3D Digital Image Correlation (3D-DIC) measurements on specimens with multi-axial stress and strain fields subjected to large deformation. [less ▲]

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See detailExperimental and numerical study of TA6V mechanical behavior under different quasi-static strain paths at room temperature
Gilles, Gaëtan ULg; Habraken, Anne ULg; Cazacu, Oana et al

in AIP Conference Proceedings (2013), 1532

This paper presents an experimental study of the quasi-static mechanical behavior of TA6V titanium alloy. Different monotonic tests were carried out in several orientations in the plane of the sheet in ... [more ▼]

This paper presents an experimental study of the quasi-static mechanical behavior of TA6V titanium alloy. Different monotonic tests were carried out in several orientations in the plane of the sheet in order to characterize the anisotropy and the tension-compression asymmetry exhibited by the material. Initial yielding is modeled by the phenomenological CPB06 criterion and Voce's isotropic hardening is used to describe its evolution. The simulation of a deep-drawing process is performed using the proposed constitutive modeling and compared with experimental data. [less ▲]

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See detailPrediction of residual stresses by FE simulations on bimetallic work rolls during cooling
Neira Torres, Ingrid ULg; Gilles, Gaëtan ULg; Tchuindjang, Jérôme Tchoufack ULg et al

in Computer Methods in Materials Science (2013), 13(1), 84-91

Bimetallic rolls used in the roughing stands of the Hot Strip Mill require mixed properties as a high wear resistance for the shell material and an enhanced toughness for the core material. The bimetallic ... [more ▼]

Bimetallic rolls used in the roughing stands of the Hot Strip Mill require mixed properties as a high wear resistance for the shell material and an enhanced toughness for the core material. The bimetallic roll studied in this paper is obtained from a vertical spin casting process followed by cooling and subsequent heat treatments. Failure of the compound roll sometimes occurs during the cooling stage of the casting route or later during the thermal treatments. It requires to deeply investigate the thermo mechanical metallurgical interactions generated during cooling and heat treatment in order to find the origin of cracks. For this purpose, a thermo metallurgic mechanical finite element model is used. However these numerical simulations require a high amount of mechanical, thermal and metallurgical parameters. In order to determinate these parameters, a study of available data for estimation of mechanical parameters was performed. Thermo physical parameters were obtained by DTA and DSC methods. Metallurgical characterization by inverse numerical method based on available CCT diagrams was performed to determine the TTT diagrams. First cooling numerical simulations are presented, allowing a rough estimate of residual stresses values and the identification of key parameters for predicting accurate residual stresses by sensitivity analysis. [less ▲]

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See detailCompression test for plastic anisotropy characterization using optical full-field dis-placement measurement technique
Tuninetti Vásquez, Victor ULg; Gilles, Gaëtan ULg; Milis, Olivier ULg et al

in Steel Research International (2012)

In this work, a constitutive law, its identification and its validation for TA6V titanium alloy are presented. The material characteri-zation is achieved by quasi-static monotonic tensile and compression ... [more ▼]

In this work, a constitutive law, its identification and its validation for TA6V titanium alloy are presented. The material characteri-zation is achieved by quasi-static monotonic tensile and compression tests at several strain rates and in three orthogonal material orientations. Constitutive model as Johnson-Cook which describes the strain rate sensitivity of the plastic material response is used in order to identify the initial yield locus at a common strain rate (10-3 s-1). The macroscopic orthotropic yield criterion chosen is the well-known CPB06 proposed by Cazacu et al., which describes both the tension/compression asymmetry and the anisotropic behavior of hcp metals and alloys. Voce type isotropic hardening model is used for simplicity reasons. A compression test on ellipsoidal cross-section specimen is selected for validation purpose, where 3 Digital Image Correlation 3D systems are used in order to acquire the evolution of the full field displacement/strain during the test. Coulomb friction coefficient between the dies and the specimen is computed by means of inverse modelling. A good agreement on the prediction of the load as a function of axial displacement of the specimen is found. [less ▲]

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See detailCompression test for metal characterization using digital image correlation and inverse modeling
Tuninetti Vásquez, Victor ULg; Gilles, Gaëtan ULg; Péron-Lührs, Vincent ULg et al

in Procedia IUTAM (2012)

In the case of sheet metal characterization, compression tests at normal direction of the sheet can be done by means of the layer compression test. Circular cylinder specimens are commonly used for ... [more ▼]

In the case of sheet metal characterization, compression tests at normal direction of the sheet can be done by means of the layer compression test. Circular cylinder specimens are commonly used for compression test but the complicated layer alignment is time consuming and may induce a wrong anisotropy characterization. This final goal explains the interest of working on elliptic shape. In this article, an elliptical cylinder specimen is proposed and tested for bulk Titanium alloy. Full-field optical technique (3D Digital Image Correlation) is used for displacement measurements by means of three camera systems (Limess), which allows out-of-plane displacement/strain fields on around 300° of the specimen. The use of this technique easily provides accurate barreling profile used to compute Coulomb friction coefficient by using inverse method. [less ▲]

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See detailExperimental and numerical study of TA-6V mechanical behavior in different monotonic loading conditions at room temperature
Gilles, Gaëtan ULg; Cazacu, Oana; Hammami, Walid ULg et al

in Procedia IUTAM (2012), 3

This paper presents an experimental characterization of the quasi-static mechanical response of a TA-6V titanium alloy in sheet form. Monotonic tests, such as uniaxial tension and compression, plane ... [more ▼]

This paper presents an experimental characterization of the quasi-static mechanical response of a TA-6V titanium alloy in sheet form. Monotonic tests, such as uniaxial tension and compression, plane strain and simple shear, were conducted along several orientations in the plane of the sheet in order to investigate the plastic anisotropy and the tension-compression asymmetry displayed by the material at the macroscopic scale. It was observed a moderate anisotropy in yielding while the anisotropy in r-ratios is very pronounced. Initial yielding is described using criteria that account for both plastic anisotropy and strength differential effects. Comparison between experimental data and FE simulation results illustrates the ability of the model to predict the mechanical response of TA-6V. [less ▲]

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See detailPhenomenological and crystal plasticity approaches to describe the mechanical behaviour of Ti6Al4V titanium alloy
Hammami, Walid ULg; Gilles, Gaëtan ULg; Habraken, Anne ULg et al

in International Journal of Material Forming (2011), 4(2), 205-2015

This paper presents a multiscale study of the quasi-static behaviour of a Ti6Al4V titanium alloy sheet. Tensile and compressive tests were carried out on specimens along several orientations from the ... [more ▼]

This paper presents a multiscale study of the quasi-static behaviour of a Ti6Al4V titanium alloy sheet. Tensile and compressive tests were carried out on specimens along several orientations from the rolling direction in order to characterise the material anisotropy. In parallel, X-Ray diffraction texture measurements were performed before and after deformation in tension. A phenomenological model (CPB06exn) and a multiscale crystal plasticity model (Multisite) were investigated to describe the mechanical behaviour of the tested material. The identification of the material parameters provides good predictions of the plastic anisotropy using both tensile and compressive data. The crystal plasticity model is in good agreement with the experiments in tension but it was observed that some improvements should be done to take into account the tension-compression asymmetry displayed by the material. Moreover both models lead to a good prediction of the Lankford’s coefficients and yield strength. [less ▲]

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See detailExperimental characterization and elasto-plastic modeling of the quasi-static mechanical response of TA-6 V at room temperature
Gilles, Gaëtan ULg; Hammami, Walid ULg; Libertiaux, Vincent ULg et al

in International Journal of Solids & Structures (2011), 48(9), 12771289

The paper presents an experimental study of the quasi-static deformation behavior of a TA-6V in sheet form. To quantify the plastic anisotropy and the tension-compression asymmetry of this material at ... [more ▼]

The paper presents an experimental study of the quasi-static deformation behavior of a TA-6V in sheet form. To quantify the plastic anisotropy and the tension-compression asymmetry of this material at room temperature, monotonic tensile and compressive tests were carried out on specimens cut out along several orientations in the plane of the sheet. It was observed that although the tensile flow stress anisotropy is very mild, the Lankford coefficients’ anisotropy is very pronounced. To describe the observed mechanical response an elastic/plastic approach was used. Yielding was described using a family of yield criteria that account for strength differential effects and allow an improved description of the anisotropy and its evolution through multiple linear transformations. Comparisons between uniaxial monotonic data and FE simulations using the model show a very good agreement. [less ▲]

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See detailExperimental characterization and constitutive modeling of TA6V mechanical behavior in plane strain state at room temperature
Gilles, Gaëtan ULg; Tuninetti Vásquez, Victor ULg; Ben Bettaieb, Mohamed ULg et al

in AIP Conference Proceedings (2011), 1383

This paper presents an experimental and theoretical study of the quasi-static behavior of TA6V titanium alloy in plane strain state. In order to quantify the anisotropy of the material, tests were carried ... [more ▼]

This paper presents an experimental and theoretical study of the quasi-static behavior of TA6V titanium alloy in plane strain state. In order to quantify the anisotropy of the material, tests were carried out at room temperature on specimens cut out from a sheet along three loading directions. The initial yield locus is described by the phenomenological CPB06ex3 criterion and Voce’s type isotropic hardening is used. Finite element simulations are performed and compared with the experiments. [less ▲]

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See detailExperimental investigations of the material behavior of Ti6Al4V titanium alloy
Rossi, Barbara ULg; Gilles, Gaëtan ULg; Zolotas, Eric et al

Report (2011)

Computer models are widely used to support the development of conventional design methods based on expensive full-scale tests or trial and error methods. Nevertheless, in order to accurately model metal ... [more ▼]

Computer models are widely used to support the development of conventional design methods based on expensive full-scale tests or trial and error methods. Nevertheless, in order to accurately model metal forming processes as well as structural behavior of load carrying elements, it is necessary to afford an accurate knowledge of the material properties. Titanium is one of the material for which various industrial sectors such as aerospace or biomedical are showing an increasing interest. This paper presents the experimental tests performed on the titanium based alloy Ti6Al4V to investigate on its mechanical behavior, especially in terms of its anisotropy and hardening. For that purpose, a classical uniaxial and a non-standard biaxial experimental equipments designed by Florès in the Materials and Structures Mechanics Laboratory of the University of Liège have been used to perform tensile, simple shear and cyclic shear tests as well as successive simple shear and plane strain tests, which provide the main contribution of this paper in the form of stress-strain curves. [less ▲]

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See detailAccurate stress computation in plane strain tensile tests for sheet metal using experimental data
Flores, P.; Tuninetti Vásquez, Victor ULg; Gilles, Gaëtan ULg et al

in Journal of Materials Processing Technology (2010), 210

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See detailMaterial parameter identification of Cazacu's model for Ti6Al4V using the simulated annealing algorithm
Gilles, Gaëtan ULg; Habraken, Anne ULg; Duchene, Laurent ULg

in Materials Science Forum (2010), 636-637

Phenomenological yield criteria are generally described by many material parameters. A technique to identify these parameters is required to find the best fit to the results of the mechanical tests. The ... [more ▼]

Phenomenological yield criteria are generally described by many material parameters. A technique to identify these parameters is required to find the best fit to the results of the mechanical tests. The parameter identification by the classical simulated annealing technique is presented in this paper. This algorithm, based on Metropolis’ works [1,2], is a global optimization method that distinguishes between different local optima to reach the global optimum. The anisotropic model used in this study is the one proposed by [3]. To prove the efficiency of the proposed algorithm, the material parameters of Ti6Al4V titanium alloy are identified and compared with those obtained using different identification procedures and the same experimental data. [less ▲]

Detailed reference viewed: 90 (35 ULg)