References of "Habraken, Anne"
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See detailStrategy of material parameters identification for non linear mechanical behavior: sensitivity of FE computation
Bouvier, Salima; Alves, L.; Habraken, Anne ULg

in Cueto, Elías; Francisco, Chinesta (Eds.) Proceedings of the 10th International ESAFORM Conference on Material Forming (2007)

The purpose of the present work is to analyze several aspects related to the connection between the constitutive models, their identification and the FEM predictions. Several issues are addressed: the ... [more ▼]

The purpose of the present work is to analyze several aspects related to the connection between the constitutive models, their identification and the FEM predictions. Several issues are addressed: the experimental data base that should be used in the identification procedure, the choice of the mechanical tests involved (monotonous and/or non-proportional loading, homogeneous or heterogeneous tests...), the identification strategies (direct or inverse FE optimization, simultaneous or sequential material parameters identification...). Besides its obvious interest, such study aim to find a good balance between the number and the type of relevant involved mechanical tests in material behavior characterization. This is an important issue for industrial applications. [less ▲]

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See detailComparisons of FEM approaches modelling the metal plastic behaviour
Habraken, Anne ULg; Gerday, Anne-Françoise ULg; Diouf, B. et al

in Cueto, Elías; Chinesta, Francisco (Eds.) Proceedings of the 10th ESAFORM Conference on Material Forming (2007)

Simple phenomenological laws (e.g. classical Hill 1948 quadratic law) are compared to more complex laws based on crystal plasticity through various numerical simulations: mechanical tests of ECAE ... [more ▼]

Simple phenomenological laws (e.g. classical Hill 1948 quadratic law) are compared to more complex laws based on crystal plasticity through various numerical simulations: mechanical tests of ECAE materials, nanoindentation of titanium alloys and copper, and large strain torsion of copper bars. Taking into consideration the complexity of the investigated processes, the numerical results present rather good agreements with experimental observations. [less ▲]

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See detailInverse modelling of nanoindentation tests to identify Ti-555 behaviour
Gerday, Anne-Françoise ULg; Clement, N.; Jacques, P. J. et al

in Proceedings of the 11th world conference on titanium (2007)

Nanoindentation is commonly used to probe local plastic properties of materials [1-4]. From these nanoindentation tests, finite element (FE) modeling is currently used to identify material data. The ... [more ▼]

Nanoindentation is commonly used to probe local plastic properties of materials [1-4]. From these nanoindentation tests, finite element (FE) modeling is currently used to identify material data. The general ambition of this research is to extract the material parameters representative of the response of a new generation of Ti alloy, called Ti-555, in order to perform simulations on representative microscopic cells and guide the optimization of the alloy. In this paper, the identification of the flow parameters of the -phase of this alloy, using a microscopic crystal plasticity-based constitutive law is described. The nanoindentation tests are performed using a pyramidal Berkovich diamond indenter and the different slip systems of the b.c.c. -phase are supposed to be activated with identical critical shear stresses. The FE nanoindentation force-displacement curves obtained with the microscopic constitutive law are compared to the experimental ones. The influence of the orientation of the grains is also analysed. A previous sensivity analysis on different parameters with different constitutive laws and materials has shown a great influence of different parameters on the nanoindentation results but almost no influence of other parameters [5-6]. [less ▲]

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See detailDevelopment of an inverse method for identification of materials parameters in the single point incremental sheet forming process
Bouffioux, Chantal ULg; Henrard, Christophe ULg; Gu, Jun et al

in Tisza, M. (Ed.) Proceedings of the IDDRG 2007 International Conference (2007)

The purpose of this article is to develop an inverse method for adjusting the material parameters during single point incremental forming. The main idea consists in simulating tests performed on the same ... [more ▼]

The purpose of this article is to develop an inverse method for adjusting the material parameters during single point incremental forming. The main idea consists in simulating tests performed on the same machine as the one used for the process itself. This reduces the costs of the equipment since no specific and costly standard test equipment is needed. Moreover, it has the advantage that the material parameters are fitted for a heterogeneous stress and strain state occurring during the real process. Before using the inverse method, the numerical results must be compared with the experimental ones. Several boundary conditions will be tested. [less ▲]

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See detailMicro and macro investigation on the hardening of a titanium alloy
Lelotte, Thomas; Rossi, Barbara ULg; Habraken, Anne ULg

in 11th World conference on titanium: Ti 2007, Kyoto 3-7 June 2007 (2007)

This paper presents the experimental and numerical tests made on the Titanium based alloy Ti6A14V to identify its yield locus and the hardening behaviour. A bi-axial experimental equipment has been used ... [more ▼]

This paper presents the experimental and numerical tests made on the Titanium based alloy Ti6A14V to identify its yield locus and the hardening behaviour. A bi-axial experimental equipment has been used to perform cyclic shear tests, simple shear tests and successive simple shear tests and plane-strain tests. Coupled with classical tensile tests, these tests enable to identify the yield locus and the hardening model. Teodosiu and Hu’s hardening law and isotropic Swift type hardening and kinematic Armstrong Frederick hardening models have been investigated. [less ▲]

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See detailModelling the vertical centrifugal casting of large bimetallic rolling mills
Studer, Léo ULg; Habraken, Anne ULg; Pirotton, Michel ULg et al

in Onate, E.; Papadrakis, M.; Schrefler, B. (Eds.) Proceedings of the Conference of Computational Methods for Coupled Problems in Science and Engineering 2 (2007)

In order to take into account the dynamical effects of molten metal during solidification, we want to interface a metal solidification solver with a flow dynamics solver.

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See detailStudy of axes rotation during simple shear tests on aluminium sheets
Duchene, Laurent ULg; Diouf, B.; Lelotte, T. et al

in César de Sa, J. M. A.; Santos, Abel D. (Eds.) Proceedings of the 9th International Conference NUMIFORM 2007 (2007)

In order to model accurately the anisotropic material behavior during finite element simulations, a precise description of the material yield locus is required. Beside the shape (linked to the material ... [more ▼]

In order to model accurately the anisotropic material behavior during finite element simulations, a precise description of the material yield locus is required. Beside the shape (linked to the material model used), the size (related to the isotropic hardening) and the position (kinematic hardening) of the yield locus, its orientation is of particular interest when large rotations of the material are encountered during the simulations. This paper proposes three distinct methods for the determination of the material yield locus rotation: a method based on the Constant Symmetric Local Velocity Gradient (CSLVG), a corotational method and a method based on the Mandel spin. These methods are compared during simple shear tests of an aluminum sheet. [less ▲]

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See detailPlane strain test for metal sheet characterization
Flores, Paulo; Bonnet, Félix; Habraken, Anne ULg

in Key Engineering Materials [=KEM] (2007), 344

This article shows the influence of a plane strain test specimen geometry on the measurable strain field and the influence of free edge effects over the stress computation. The experimental strain field ... [more ▼]

This article shows the influence of a plane strain test specimen geometry on the measurable strain field and the influence of free edge effects over the stress computation. The experimental strain field distribution is measured over the whole deformable zone of a plane strain test specimen by an optical strain gauge. The chosen material is the DC06 IF steel of 0.8 mm thickness. The stress field is computed for several geometries at different strain levels by a Finite Element (FE) commercial code (Samcef ®). The results show that the stress field is sensitive to the specimen’s geometry and also to the tested material (strain field behavior is independent of material) and, based on results, an optimal specimen geometry is proposed in order to minimized the stress computation error. [less ▲]

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See detailMultiscale Approaches
Duchene, Laurent ULg; Habraken, Anne ULg

in Chinesta, F.; Cueto, E. (Eds.) Advances in Material Forming - Esaform 10 years on (2007)

This paper presents a review of the main families of multiscale models. A first group of models is interested in an accurate modelling of the texture induced anisotropy of the material during numerical ... [more ▼]

This paper presents a review of the main families of multiscale models. A first group of models is interested in an accurate modelling of the texture induced anisotropy of the material during numerical simulations. The differences between the proposed models are mainly due to different choices concerning the necessary compromise between the importance of the microscopic roots of the model and the maximum admissible computation time. The length scale of the investigated process is also an important parameter. The second group of micro-macro models is based on an analysis of the dislocation densities linked to the plastic deformations. A discussion concerning the past evolution, the recent achievements and the future trends concerning multiscale models is also provided. [less ▲]

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See detailLength changes and texture prediction during free end torsion test of copper bars with FEM and remeshing techniques
Duchene, Laurent ULg; El Houdaigui, Fouad; Habraken, Anne ULg

in International Journal of Plasticity (2007), 23(8), 1417-1438

FEM numerical simulations of the experimental free end torsion tests [Toth, L.S., Jonas, J.J., Daniel, D., Bailey, J.A., 1992. Texture development and length changes in copper bars subjected to free end ... [more ▼]

FEM numerical simulations of the experimental free end torsion tests [Toth, L.S., Jonas, J.J., Daniel, D., Bailey, J.A., 1992. Texture development and length changes in copper bars subjected to free end torsion. Textures Microstruct. 19, 245–262] of copper cylindrical bars were analysed in the present study. The self-made Finite Element (FE) code LAGAMINE was used to compute numerical prediction of the Swift effect, i.e. the lengthening of the cylinder during the torsion. The material behaviour was represented by an interpolation law [Habraken, A.M., Ducheˆne, L., 2004. Anisotropic elasto-plastic finite element analysis using a stress–strain interpolation method based on a polycrystalline model. Int. J. Plasticity 20 (8–9), 1525–1560] linked with a Taylor polycrystal plasticity model either based on a strain rate insensitive or a visco-plastic crystal plasticity model. The influence of texture evolution was analysed. A torsion dedicated remeshing technique was developed to allow very large strain simulations. Predicted axial lengthening and predicted textures were compared to experimental measurements. A good agreement was obtained for shear strain up to 2.0. The Swift effect related angular shift of the pole figure maxima from symmetrical orientations was reproduced correctly. [less ▲]

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See detailFinite element study of the effect of some local defects on the risk of transverse cracking in continuous casting of steel slabs
Pascon, Frédéric ULg; Habraken, Anne ULg

in Computer Methods in Applied Mechanics & Engineering (2007), 196

This paper introduces a numerical 2.5D model of continuous casting of steel slabs. This model is based on the finite element method and it has been applied to the study of some local defects in a ... [more ▼]

This paper introduces a numerical 2.5D model of continuous casting of steel slabs. This model is based on the finite element method and it has been applied to the study of some local defects in a continuous caster, such as partial blockage of nozzles (leading to a local reduction of secondary cooling rate), locking or misalignment of rolls. The purpose of the study was the evaluation of the effect of such defects on the risk of transverse cracking during bending and unbending operations. To do so, the simulation at macro-scale of the complete process has been first performed in standard conditions to get reference values and then each defect has been introduced. Defining two indexes (indicators) of the risk of transverse cracking, it has been possible to classify the defects in terms of risk increase, helping steel producers to focus on the most critical problems. [less ▲]

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See detailModel Identification and FE Simulations Effect of Different Yield Loci and Hardening Laws in Sheet Forming
Flores, Paulo; Duchene, Laurent ULg; Bouffioux, Chantal ULg et al

in International Journal of Plasticity (2007), 23(3), 420-449

The bi-axial experimental equipment [Flores, P., Rondia, E., Habraken, A.M., 2005a. Development of an experimental equipment for the identification of constitutive laws (Special Issue). International ... [more ▼]

The bi-axial experimental equipment [Flores, P., Rondia, E., Habraken, A.M., 2005a. Development of an experimental equipment for the identification of constitutive laws (Special Issue). International Journal of Forming Processes] developed by Flores enables to perform Bauschinger shear tests and successive or simultaneous simple shear tests and plane strain tests. Flores investigates the material behavior with the help of classical tensile tests and the ones performed in his bi-axial machine in order to identify the yield locus and the hardening model. With tests performed on one steel grade, the methods applied to identify classical yield surfaces such as [Hill, R., 1948. A theory of the yielding and plastic flow of anisotropic materials. Proceedings of the Royal Society of London A 193, 281–297; Hosford, W.F., 1979. On yield loci of anisotropic cubic metals. In: Proceedings of the 7th North American Metalworking Conf. (NMRC), SME, Dearborn, MI, pp. 191–197] ones as well as isotropic Swift type hardening, kinematic Armstrong–Frederick or Teodosiu and Hu hardening models are explained. Comparison with the Taylor–Bishop–Hill yield locus is also provided. The effect of both yield locus and hardening model choices is presented for two applications: plane strain tensile test and Single Point Incremental Forming (SPIF). [less ▲]

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See detailStudy of a 2024 aluminium rod produced by Rotary Forging
Habraken, Anne ULg; Bouffioux, Chantal ULg; Carton, Marc ULg et al

in Journal of Materials Processing Technology (2007), 184

An investigation of the rotary forging process of a 2024 aluminium rod is summarised. Some dispersion in mechanical properties and chemical composition of the base material is permitted. Samples of two ... [more ▼]

An investigation of the rotary forging process of a 2024 aluminium rod is summarised. Some dispersion in mechanical properties and chemical composition of the base material is permitted. Samples of two material batches were selected: one just stays near the upper limit of tolerance and the other has mean properties. Tensile and compression tests confirm the different mechanical behaviours and allow the identification of constitutive laws parameters. Optical metallography after T3 and T10 thermal treatments and differential thermal analysis provide the grain size and precipitation characteristics of each material batch, which explain their different mechanical behaviours. The industrial rod studied is usually forged in two operations: a first forging process, then a T10 thermal treatment followed by a second forging step. Industrial practise shows that manufacturing the rod with one forging step fails. FEM simulations of the process coupled with a fracture criterion confirm the advantage of a two-step process compared to a single forging step. [less ▲]

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See detailCorrecting tensile test results of ECAE-deformed aluminium
Poortmans, Stijn; Boubakar, Diouf; Habraken, Anne ULg et al

in Scripta Materialia (2007), 56(9), 749-752

Performing tensile tests on ECAE material reveals a long post-uniform elongation. In order to calculate correct true stress–true strain diagrams, three different approaches are used: measurements of the ... [more ▼]

Performing tensile tests on ECAE material reveals a long post-uniform elongation. In order to calculate correct true stress–true strain diagrams, three different approaches are used: measurements of the actual sample geometry, a neck evolution model proposed by Segal [V.M. Segal, S Ferrasse, F. Alford, Mater. Sci. Eng. A442 (2006) 321–326] and an inverse modelling method by finite element (FE) simulations. [less ▲]

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See detailNumerical study to identify the material parameters of a damage model
Schwartz, Renée ULg; Castagne, Sylvie; Habraken, Anne ULg

in Computer Methods in Materials Science (2007), 7(2), 237-242

In the continuous casting (CC) process, transversal cracks happen. This type of macroscopic damage is due to the process loading in the bending and unbending area of the CC line. In order to study this ... [more ▼]

In the continuous casting (CC) process, transversal cracks happen. This type of macroscopic damage is due to the process loading in the bending and unbending area of the CC line. In order to study this damage, a 2D model was developed. It simulates the intergranular crack at the mesoscopic level. Already validated for a microalloyed steel with C level < 0.1 wt%, this model must be extended to peritectic and stainless steels. The first step is to identify the model parameters for these grades. The type and the quantity of hot tensile tests required to identify a single set of parameters for the damage law must be determined. So, simulations of hot tensile tests of notched samples are needed. The computed stress and strain histories are applied on the representative mesoscopic cell and the moment of rupture is determined in function of the input parameters. Thanks to inverse modelling, the parameters of the damage law are adapted in order to get one single set of parameters with only two different geometries of notch. [less ▲]

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See detailValidation of a new finite element for incremental forming simulation using a dynamic explicit approach
Henrard, Christophe ULg; Bouffioux, Chantal ULg; Duchene, Laurent ULg et al

in Key Engineering Materials [=KEM] (2007), 344

A new method for modeling the contact between the tool and the metal sheet for the incremental forming process was developed based on a dynamic explicit time integration scheme. The main advantage of this ... [more ▼]

A new method for modeling the contact between the tool and the metal sheet for the incremental forming process was developed based on a dynamic explicit time integration scheme. The main advantage of this method is that it uses the actual contact location instead of fixed positions, e.g. integration or nodal points. The purpose of this article is to compare the efficiency of the new method, as far as accuracy and computation time are concerned, with finite element simulations using a classic static implicit approach. In addition, a sensitivity analysis of the mesh density will show that bigger elements can be used with the new method compared to those used in classic simulations. [less ▲]

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See detailA damage constitutive law for steel elevated temperature. Identification of the parameters
Castagne, Sylvie; Talamona, D.; Habraken, Anne ULg

in International Journal of Material Processing (2007), (1), 23-43

This paper presents a methodology of damage analysis at elevated temperature using the finite element method. Both the model and the methodology to identify parameters are summarized. The mechanical ... [more ▼]

This paper presents a methodology of damage analysis at elevated temperature using the finite element method. Both the model and the methodology to identify parameters are summarized. The mechanical properties are established using compression tests at elevated temperature. An elasto-visco-plastic model depending on temperature is identified. A metallographic analysis is used to determine the original size and morphology of the austenitic grains. The experimental damage analyses consist in acoustic tests in order to determine the apparition of the first crack during compression. Finite element simulations of these experiments allow the determination of the damage parameters using a reverse method. [less ▲]

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See detailSpringback and Twist Prediction of Roll Formed Parts
Bui, Quoc Viet; Boman, Romain ULg; Papeleux, Luc ULg et al

in Santos, Abel D.; Barata da Rocha, A. (Eds.) Proceedings of the IDDRG 2006 International Deep Drawing Research Group, Drawing the things to come, Trends and Advances in Sheet Metal Forming (2006, June)

In the construction market, Roll Forming is the reference forming process. Numerous parts are achieved in such a way: purlins, steeldecks or suspended ceiling parts are examples of it. Roll Forming is ... [more ▼]

In the construction market, Roll Forming is the reference forming process. Numerous parts are achieved in such a way: purlins, steeldecks or suspended ceiling parts are examples of it. Roll Forming is also more and more used in the automotive industry, as it constitutes a good alternative to forming for High Strength Steels. Among the major requirements to obtain a defect-free product are outlined: the accurate geometry of the part, the taking into account of the springback as well as the prediction of twist. Furthermore, the roll forming operation could be only the first forming operation: the part could be curved or locally deep drawn afterwards. FE codes could allow fulfilling these requirements. However, they need significant advances in terms of material model description and numerical development. This paper presents the work done in order to predict the geometry and the behaviour of a roll formed part: First the material is characterized in complex strain paths in order to identify elaborated microstructural model like Teodosiu’s one. This model is able to take into account Bauschinger effect, orthogonal strain paths, isotropic/kinematic hardening. The METAFOR code is then used to have a better understanding of the mechanics of the deformation of the strip during the forming process. Several experimental campaigns were performed on the I-R&D ARCELOR roll forming machine to define a strong database in order to validate the numerical results. The geometry of machine as well as the shape of the channels inside and outside the RF machine were measured. Some experiments were even carried out in order to generate defects like twist in the roll formed profile. [less ▲]

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See detailFinite element simulations of nanoindentation in beta metastable Ti alloys
Gerday, Anne-Françoise ULg; Clement, N.; Jacques, P. J. et al

in Juster, Neal; Rosochowski, Andrzej (Eds.) Proceedings of the 9th International ESAFORM Conference on Material Forming (2006)

Nanoindentation is a versatile tool to probe local plastic properties of materials. Finite element (FE) modelling is currently used to identify material data from nanoindentation tests [1-4]. The general ... [more ▼]

Nanoindentation is a versatile tool to probe local plastic properties of materials. Finite element (FE) modelling is currently used to identify material data from nanoindentation tests [1-4]. The general ambition of this research is to extract the material parameters describing the response of a new Ti alloy, called Ti-555, in order to perform simulations on representative microscopic cells and guide the optimisation of this alloy. In this paper, the first steps of the identification of the macroscopic flow parameters of the β-phase are described. The nanoindentation tests using a pyramidal Berkovich diamond indenter are performed in the β-phase. The FEM results with different parameters of an isotropic and anisotropic elasto-plastic (EP) constitutive law are analyzed and the predicted shapes are compared to the final shape of the indented material. The FE results very much depend on physical model choices, and cannot rely on an automatic identification approach. [less ▲]

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See detailOut-of-plane displacement derivative measurement: comparison of results obtained by a shearographic interferometer using the separation of the polarization states and the finite element method
Rosso, Vanessa; Zhang, Lihong ULg; Michel, Fabrice ULg et al

in Mathieu, P. (Ed.) Proceedings of Photonics North Conference 2006 (2006)

An original experimental setup for shearography with metrological applications is presented herein. The simplicity and the efficiency of the setup are provided by a shearing device, a prism that separates ... [more ▼]

An original experimental setup for shearography with metrological applications is presented herein. The simplicity and the efficiency of the setup are provided by a shearing device, a prism that separates the TE and TM polarization modes with a coating and a thin glass plate attached on its face. The temporal phase shifting method is applied through the use of a liquid crystal variable retarder. The use of this shearing device enables an in-line and almost-common path configuration for the shearing interferometer, a path that leads to high stability of the interferometer and a low sensitivity to external disturbances. In order to prove the efficiency and the accuracy of this speckle shearing interferometer, the out-of-plane displacement derivative relative to the shearing interferometry direction of a centrally loaded steel plate has been measured by the shearographic interferometer and then compared with the out-of-plane displacement derivative computed from the displacement field provided by the finite element method. The results are in good agreement. [less ▲]

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