References of "Habraken, Anne"
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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 ▲]

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See detailMaterial data identification to model the single point incremental forming process
Bouffioux, Chantal ULg; Pouteau, P.; Duchene, Laurent ULg et al

in International Journal of Material Forming (2010), 3(Suppl. 1), 979-982

In this study, the Single Point Incremental Forming process (SPIF) is applied on a specific aluminium alloy used in the aerospace industry since this technique and material combine a low specific weight ... [more ▼]

In this study, the Single Point Incremental Forming process (SPIF) is applied on a specific aluminium alloy used in the aerospace industry since this technique and material combine a low specific weight, high strength and stiffness properties and high strain levels. To be able to optimize the process, a model and its material parameters are required. It was noticed that a simple isotropic hardening model was not sufficient to provide an accurate tool force prediction [1]. Therefore an elasto-plastic law with a mixed isotropic-kinematic hardening is investigated. The inverse method coupled with the Finite Element (FE) code: "Lagamine" [2] is used to fit the material data of this complex law. In order to validate the model and the material data, a Line test and a Cone test are used. [less ▲]

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See detailMultiscale modelling of back-stress during equal-channel angular pressing
Chen, E.; Duchene, Laurent ULg; Habraken, Anne ULg et al

in Reviews of advanced materials science (2010), 25(1), 23-31

Equal-channel angular pressing (ECAP) is a well known process to produce ultrafinegrained materials. The mechanical properties of these materials, including a compressiontension asymmetry and a transient ... [more ▼]

Equal-channel angular pressing (ECAP) is a well known process to produce ultrafinegrained materials. The mechanical properties of these materials, including a compressiontension asymmetry and a transient hardening saturation in the beginning of the flow curve, largely depend on the evolution of the microstructure during ECAP. Consequently, the backstress induced by the dislocation microstructure exhibits kinematic hardening at the macroscopic scale. In this paper, commercial purity aluminium AA1050 is processed by ECAP route C. Tensile and compression specimens are machined from the post-ECAP samples. The back-stress level is estimated from the different yielding strengths of tensile tests and compression tests. Then two different models, a macroscopic phenomenological Teodosiu-type model and a microscopic dislocation-based multi-layer model, are used to predict the back-stress values. A set of parameters for Teodosiu's model is identified from simple shear tests, Bauschinger tests and orthogonal orthogonal tests. The dislocation-based multi-layer model is based on the Estrin-Tóth dislocation model and Sauzay's intragranular back-stress model. The predicted and experimental back-stresses due to ECAP are compared and critically evaluated. [less ▲]

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See detailComparison of mechanical efficiency of two microstructures of Ti5553 alloy in the case of bolted flanges submitted to tensile loading
Van Hoof, T.; Ben Bettaieb, Mohamed ULg; Lani, F. et al

in Steel Research International (2010), 81(9), 1148-1152

A combination of numerical and experimental methods is used to compare the efficiency of two microstructures of Ti5553 titanium alloy in an industrial test case. The test case consists in two parts of ... [more ▼]

A combination of numerical and experimental methods is used to compare the efficiency of two microstructures of Ti5553 titanium alloy in an industrial test case. The test case consists in two parts of sectors of aircraft engine stators linked together by an Inconel bolt and submitted to tensile loading. The efficiency of these microstructures is evaluated by using finite element (FE) models. The chosen FE models take into account elasto-visco-plastic material behaviors, contact with friction (bolt heads/flanges and flange/flange), and the initial bolt tightening. The parameters of the elasto-visco-plastic (EVP) material law are adjusted from experimental results extracted from tensile tests performed on Inconel, and Ti5553 alloys. Viscous properties are observed at different strain rates. The studied alloy is assumed to be plastically isotropic. In order to compare the fracture resistance of both microstructures, a micro-mechanical (damage based) rupture model ([4]) is used as a FE post-processing step. [less ▲]

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See detailOptimized Remeshing for Incremental Forming Simulation
Rabahallah, François ULg; Bouffioux, Chantal ULg; Duchene, Laurent ULg et al

in Proceedings of the Advances in Materials and Processing Technologies Conference (2010)

This work presents an advanced numerical methodology which aims to improve the simulations of incremental forming processes [3]. A specific numerical treatment is required to optimize the remeshing ... [more ▼]

This work presents an advanced numerical methodology which aims to improve the simulations of incremental forming processes [3]. A specific numerical treatment is required to optimize the remeshing procedure, in order to decrease the simulation CPU time and deals with the strong process nonlinearities. The algorithm remeshing procedure is implemented in the Lagamine FE code [2] developed at the University of Liège. An elastoplastic law is combined with an isotropic kinematic hardening model. The identification procedure for the material parameters determination takes into account a set of mechanical tests (inverse approach). Numerical simulations of the forming of a pyramid part with two wall angles are performed in order to address the robustness of the implementation and the ability of this numerical methodology to predict the force values. Comparisons between measured and predicted force values are performed. [less ▲]

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See detailMultiaxial fatigue damage modeling of Ti6Al4V alloy
Marmi, Abdeljalil ULg; Habraken, Anne ULg; Duchene, Laurent ULg

in Proceedings of the ICMFF9 Conference (2010)

The aim of this study is to present a new multiaxial fatigue model based on phenomenological approach for the proportional loading. The model estimations are compared to the classical Lemaitre-Chaboche [1 ... [more ▼]

The aim of this study is to present a new multiaxial fatigue model based on phenomenological approach for the proportional loading. The model estimations are compared to the classical Lemaitre-Chaboche [1] fatigue model and experimental results. The comparison is done by simulation of SN curves of notched and un-notched forged TA6V samples. To take into account the effect of stress gradient near notch root, the applied loads such as stress amplitude and Von Mises stress are affected by the triaxialty function introduced by Lemaitre [2]. The models enhanced by triaxialty function give correct results for life estimation of notched samples. [less ▲]

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See detailNumerical Modeling of Representative Cells of Ti-5553 Using Periodic Homogenization Technique
Gerday, Anne-Françoise ULg; Ben Bettaieb, Mohamed ULg; Pascon, Frédéric ULg et al

in Oñate, E.; Owen, D. R. J. (Eds.) Computational plasticity X. Fundamentals and applications (2009, September)

This article focuses on the modeling of representative cells of Ti-5553 using the periodic homogenization theory and a microscopic constitutive law.

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See detailCrystal Plasticity Modelling of Monotonic Shear Tests on Pure Titanium
Hammami, Walid ULg; Bouvier, S.; Duchene, Laurent ULg et al

in Oñate, E.; Owen, D. R. J. (Eds.) Computational plasticity X. Fundamentals and applications (2009, September)

This study consists in the modelling of shear tests performed on pure titanium using a polycrystalline model. Numerical and experimental results are presented.

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See detailThe Role of Void Evolution on the bendability of Steel Sheets
Ben Bettaieb, Mohamed ULg; Lemoine, Xavier; Duchene, Laurent ULg et al

in Oñate, E.; Owen, D. R. J. (Eds.) Computational plasticity X. Fundamentals and applications (2009, September)

In the present contribution, an advanced Gurson model is developed and implemented in the Lagamine finite element code[1. This model is used to simulate the bending process and to predict the bendability ... [more ▼]

In the present contribution, an advanced Gurson model is developed and implemented in the Lagamine finite element code[1. This model is used to simulate the bending process and to predict the bendability of the studied sheet. [less ▲]

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See detailEvaluation of different advanced finite element concepts for detailed stress analysis of laminated composite structures
Rah, K.; Van Paepegem, W.; Habraken, Anne ULg et al

in International Journal of Material Forming (2009), volume 2(Supplément 1), 943-947

Despite their high specific stiffness and strength, laminated composite materials, e.g. fibre-reinforced plastic plies stacked at different fibre orientations, are susceptible to damage. Damage can be ... [more ▼]

Despite their high specific stiffness and strength, laminated composite materials, e.g. fibre-reinforced plastic plies stacked at different fibre orientations, are susceptible to damage. Damage can be divided into interalaminar damage and interlaminar damage. Delamination is a typical kind of interlaminar damage which occurs in laminated composite materials, often accompanied with intralaminar damage, and may lead to a catastrophic structural collapse. The first and most crucial step in the prediction of failure of Laminated Composite Structures (LCS) is to accurately determine the stresses, particularly the three transverse stress components, also called the interlaminar stresses. It is proposed in the present paper that the integration of a displacement based solid-shell formulation and partial-hybrid stress formulation will lead to an accurate and robust solid-shell element, suitable for the efficient and detailed interlaminar stress calculation. [less ▲]

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See detailCrystal plasticity prediction of Lankford coefficient using the MULTISITE model: influence of the critical resolved shear stresses
Hammami, Walid ULg; Delannay, Laurent; Duchene, Laurent ULg et al

in International Journal of Material Forming (2009, August), 2(Supplément 1), 65-68

The MULTISITE model [1] is based on polycrystalline plasticity and the underlying hypotheses of the model are (i) that the deformation of each grain is significantly influenced by the interaction with a ... [more ▼]

The MULTISITE model [1] is based on polycrystalline plasticity and the underlying hypotheses of the model are (i) that the deformation of each grain is significantly influenced by the interaction with a limited number of adjacent grains, and (ii) that local strains deviate from their macroscopic average according to specific “relaxation modes”. The LAMEL model [2] is reformulated into the more general elastic-viscoplastic MULTISITE model permitting various relaxation modes. This model has been validated for cubic materials but hexagonal close-packed (HCP) crystals usually demonstrate larger anisotropy than cubic crystals. The model was used to simulate uniaxial tensile tests performed on rolled sheets made of Ti-6Al-4V. The Lankford coefficients (r) calculated in various directions in the plane of the sheet were analysed. In this study, different grain interaction hypotheses were tested. Besides, it appeared that the value of the critical resolved shear stresses (CRSS) of the different slip system families of the HCP metal had significant effects on the results. Their influence as well as the influence of the strain rate sensitivity parameter was examined. [less ▲]

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See detailInterests and limitations of nanoindentation for bulk multiphase material identification: Application to the β phase of Ti-5553
Gerday, Anne-Françoise ULg; Ben Bettaieb, Mohamed ULg; Duchene, Laurent ULg et al

in Acta Materialia (2009), (57), 5186-5195

This paper focuses on the numerical modeling of nanoindentation tests. The first goal of this study is to collect essential material parameters and boundary conditions from the literature and to complete ... [more ▼]

This paper focuses on the numerical modeling of nanoindentation tests. The first goal of this study is to collect essential material parameters and boundary conditions from the literature and to complete the data required to accurately model nanoindentation tests. The second goal of this study consists in validating the material parameters identified from macroscopic tensile tests of the body-centered cubic b phase of Ti-5553, a new generation of titanium alloy. This validation is performed looking at experimental and numerical nanoindentation curves obtained for different grain orientations. [less ▲]

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See detailMultiaxial fatigue damage modelling at Macro scale of Ti6AL4V alloy
Marmi, Abdeljalil ULg; Habraken, Anne ULg; Duchene, Laurent ULg

in International Journal of Fatigue (2009), 31

The Lemaitre and Chaboche fatigue model is investigated in order to predict the fatigue life of tensile samples with and without notches, defining different stress concentration fields. Elastoplastic FE ... [more ▼]

The Lemaitre and Chaboche fatigue model is investigated in order to predict the fatigue life of tensile samples with and without notches, defining different stress concentration fields. Elastoplastic FE simulations based on anisotropic yield locus description were carried out in order to obtain the stress and strain distributions near the notch root. The Lemaitre and Chaboche fatigue model was applied using the point method (local approach) and the gradient method (non-local approach). [less ▲]

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See detailValidation d'un calcul thermique métallurgique
El Bartali, Ahmed ULg; Zhang, Lihong ULg; Studer, Léo ULg et al

in Appolaire, B.; Arbab Chirani, S.; Calloch, S. (Eds.) et al Mécanique et mécanismes des changements de phases (2009)

Les sollicitations thermomécaniques en général, et les traitements thermiques en particulier, constituent un mode de sollicitation rencontré fréquemment dans le milieu industriel. Pour répondre aux ... [more ▼]

Les sollicitations thermomécaniques en général, et les traitements thermiques en particulier, constituent un mode de sollicitation rencontré fréquemment dans le milieu industriel. Pour répondre aux besoins industriels, réduire les coûts et augmenter les cadences de fabrication, éviter les fissurations et les endommagements après le traitement thermique, la simulation numérique est un outil précieux. De fait, dans un procédé de traitement thermique, il y a des aspects thermiques, métallurgiques et mécaniques. Pour effectuer une simulation numérique complète, il faut établir des modèles pour ces différents aspects et identifier leurs paramètres respectifs. En particulier pour l’aspect métallurgique, il faut connaitre la cinétique de transformation du matériau étudié. Cette cinétique est donnée par les courbes de transformations isothermes (TTT, pour Time, Temperature, Transform) ou par les courbes de transformations en refroidissement continu (CCT, pour Continus Cooling Transformation). Ce papier présente une validation du modèle de Kirkaldy (Kirkaldy et al., 1979) pour définir un diagramme TTT et une validation limitée à l’aspect thermique métallurgique d’un modèle éléments finis thermomécanique métallurgique (Habraken et Bourdouxhe, 1992) qui permet de calculer un diagramme CCT à partir de la donnée du diagramme TTT. Les cas de 2 aciers sont considérés, un acier carbone-manganèse et un acier fortement allié. [less ▲]

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See detailModeling the Vertical Spincasting of Large Bimetallic Rolling Mill Rolls
Studer, Léo ULg; Detrembleur, Sylvain ULg; Dewals, Benjamin ULg et al

in Ambrosio, J. (Ed.) Proceedings of the 7th EUROMECH Solid Mechanics Conference (2009)

In order to take into account the dynamic effects of molten metal during solidification, a methodology is presented to interface a metal solidification solver (coupled thermal mechanical metallurgical ... [more ▼]

In order to take into account the dynamic effects of molten metal during solidification, a methodology is presented to interface a metal solidification solver (coupled thermal mechanical metallurgical finite elements solver) with a specifically developed flow dynamics solver. (flow dynamics and thermics finite volume solver) The numerical set of tools is designed to be used for the simulation of bimetallic hot rolling mill rolls vertical spincasting. Modeling the industrial process for these products imply certain specifications on the numerical methods used, mainly due to the size of the geometrical domain, low Rossby & Ekman numbers, and a high Reynolds number. [less ▲]

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See detailStudy of the formability of steels
Ben Bettaieb, Mohamed ULg; Lemoine, X.; Duchene, Laurent ULg et al

in Proceedings of the International ESAFORM Conference 2009 (2009)

In the present contribution, a new advanced Gurson model [1] is developed. This new model is an extension of the initial one, to the plastic anisotropy and the mixed (isotropic+ kinematic) hardening of ... [more ▼]

In the present contribution, a new advanced Gurson model [1] is developed. This new model is an extension of the initial one, to the plastic anisotropy and the mixed (isotropic+ kinematic) hardening of the fully dense matrix. The nucleation and the growth phases are considered by integrating the empirical laws developed by Bouaziz et al. [2] in this new model. These laws, identified on the basis of X-ray microtomography results, display the triaxiality effect on the nucleation and the growth of cavities. This advanced Gurson model is implemented into a finite element code by using an implicit-explicit integration scheme. FE simulations study the behavior of a sample submitted to tensile test and assess the influence of nucleation and growth laws on the formability of this sample. [less ▲]

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See detailModelling compression tests on aluminium produced by equal channel angular extrusion
Poortmans, Stijn; Duchene, Laurent ULg; Habraken, Anne ULg et al

in Acta Materialia (2009)

The main objective of this paper was to characterize the mechanical properties of commercial purity aluminium AA1050 after being submitted to the equal channel angular extrusion (ECAE) process ... [more ▼]

The main objective of this paper was to characterize the mechanical properties of commercial purity aluminium AA1050 after being submitted to the equal channel angular extrusion (ECAE) process. Compression tests on cylindrical samples extracted from ECAE material are extensively described. The influence of ECAE conditions (number of passes, route, etc.) on the mechanical response is assessed. The extraction of the material behaviour from the experimental results is not straightforward because of inhomogeneities occurring during the test. Therefore, an inverse modelling with the finite element method was used to obtain accurate material parameters by optimization. It appeared that an accurate material yield locus (based on texture analysis) is necessary in order to reproduce the anisotropic behaviour of the ECAE material. On the other hand, its hardening behaviour during compression tests was satisfactorily represented by an elastic (near) perfectly plastic model. [less ▲]

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