References of "Habraken, Anne"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailNumerical study of the fatigue crack in welded beam-to-column connection using cohesive zone model
Lequesne, Cédric ULg; Plumier, André ULg; Degée, Hervé ULg et al

in Proceedings of the International Conference on Fracture and Damage Mechanics V (2006)

The fatigue behaviour of the welded beam-to-column connections of steel moment resisting frame in seismic area must be evaluated. The cohesive zone model is an efficient solution to study such connections ... [more ▼]

The fatigue behaviour of the welded beam-to-column connections of steel moment resisting frame in seismic area must be evaluated. The cohesive zone model is an efficient solution to study such connections by finite elements. It respects the energetic conservation and avoids numerical issues. A three-dimensional cohesive zone model element has been implemented in the home made finite element code Lagamine [1]. It is coupled with the fatigue continuum damage model of Lemaître and Chaboche [2]. The cohesive parameters are identified by the inverse method applied on a three points bending test modelling. [less ▲]

Detailed reference viewed: 55 (13 ULg)
Full Text
Peer Reviewed
See detailInhomogeneous and anisotropic deformation behavior and strain hardening of ultrafine-grained aluminium by ECAP
Poortmans, Stijn; El Houdaigui, Fouad; Habraken, Anne ULg et al

in Zhu, Y. T.; Langdon, T. G.; Horita, Z. (Eds.) et al Proceedings of the Ultrafine Grained Materials IV Conference (2006)

Hot-rolled AA1050 commercial pure aluminum was deformed by ECAP (Equal Channel Angular Pressing) at room temperature following route BC for 8 passes. Mechanical testing at room temperature on both hot ... [more ▼]

Hot-rolled AA1050 commercial pure aluminum was deformed by ECAP (Equal Channel Angular Pressing) at room temperature following route BC for 8 passes. Mechanical testing at room temperature on both hot-rolled aluminum and aluminum after ECAP consisted of uniaxial tension, axisymmetric compression and shear by torsion. The phenomenological Hill’s criterion identified from texture data accounts for the observed tension-compression asymmetry due to ECAP and predicts torsion yielding close to measurements. FE simulations of the compression tests are performed with a Hill model or a Minty micro-macro model and coupled with an isotropic Voce saturation hardening law. These simulations compute the inhomogeneous behavior due to barreling, the observed sample anisotropy and the force-displacement curve. Comparisons of numerical and experiments results provide a first identification of the hardening parameters and the friction coefficient during compression tests. [less ▲]

Detailed reference viewed: 93 (1 ULg)
Full Text
Peer Reviewed
See detailPrediction of deformation textures in zirconium based on a simplified modelling of grain interaction
Lelotte, Thomas; Delannay, L.; Habraken, Anne ULg

in Khan, A. S. (Ed.) Proceedings of the Plasticity Conference 2006 (2006)

The goal of this study is to apply a “multisite” crystal plasticity model to the prediction of texture evolution in zirconium deformed at high temperature. The model under consideration is an extension of ... [more ▼]

The goal of this study is to apply a “multisite” crystal plasticity model to the prediction of texture evolution in zirconium deformed at high temperature. The model under consideration is an extension of the elastic-viscoplastic “multisite model” proposed by Delannay et al. [2005] which has been adapted to account for a new type of grain interaction (Van Houtte et al. [2005]). Predictions of the model are compared to experimental data. Two forming processes are considered: sheet rolling (Lebensohn et al. [1994]) and the torsion of a cylindrical bar (Sanchez et al. [2001]). [less ▲]

Detailed reference viewed: 15 (0 ULg)
Full Text
Peer Reviewed
See detailAnalysis of speckle patterns for deformation measurements by DIC
Lecompte, David; Sol, H.; Vantomme, J. et al

in Slangen, Pierre; Cerruti, Christine (Eds.) Proceedings of SPIE Vol. 6341 (2006)

Digital Image Correlation (DIC) – also referred to as white light speckle technique – is an optical-numerical full-field measuring technique, which offers the possibility to determine in-plane ... [more ▼]

Digital Image Correlation (DIC) – also referred to as white light speckle technique – is an optical-numerical full-field measuring technique, which offers the possibility to determine in-plane displacement fields at the surface of objects under any kind of loading. For an optimal use of the method, the object of interest has to be covered with a speckle pattern. The present paper studies the efficiency of a random speckle pattern and its influence on the measured in-plane displacements with respect to the subset size. First a randomly sprayed speckle pattern is photographed three times. Each picture is taken with a different zoom, yielding three speckle patterns, which are different by the size of the speckles. Secondly a number of speckle patterns are generated numerically using a given speckle size and image coverage. Subsequently, each speckle pattern image undergoes a numerically controlled deformation, which is measured with digital image correlation software. Both imposed and measured displacements are compared and it is shown that the size of the speckles combined with the size of the used pixel subset, clearly influences the accuracy of the measured displacements. Furthermore it is shown that it is possible to create an optimal speckle pattern when a given subset size is chosen. [less ▲]

Detailed reference viewed: 140 (4 ULg)
Full Text
Peer Reviewed
See detailComparison between homogeneous and heterogeneous field information for plastic material identification
Lecompte, D.; Sol, H.; Vantomme, J. et al

in Grédiac, Michel; Huntley, Jonathan (Eds.) Proceedings of Photomecanics Conference 2006 (2006)

The accuracy of a Finite Element Simulation for plastic deformation strongly depends on the chosen constitutive laws and the value of the material parameters within these laws. The identification of those ... [more ▼]

The accuracy of a Finite Element Simulation for plastic deformation strongly depends on the chosen constitutive laws and the value of the material parameters within these laws. The identification of those mechanical parameters can be done based on homogeneous stress and strain fields such as those obtained in uniaxial tensile tests and simple shear tests performed in different plane material directions. Another way to identify plastic material parameters is by inverse modeling of an experiment exhibiting a heterogeneous stress and strain field. Experimental forces and strains are in this case compared to the simulated ones and it is tried to reduce the difference in a least-squares sense by optimizing the model parameters. The optimization technique used is this case is gradient based, which means that at every iteration a sensitivity calculation has to be performed in order to indicate the direction in which the parameters are to be identified. The basic principle of the inverse modeling procedure as it is used for parameter identification is the generation of a complex and heterogeneous deformation field that contains as much information as possible about the parameters to be identified. One way of obtaining such a non-homogeneous deformation is by altering the geometry of the specimen for a uniaxial test. Another possibility is to make the loading conditions more complex. In this paper both options are actually combined by using a biaxial tensile test on a perforated cruciform specimen. In the present paper, the work hardening of the material is assumed to be isotropic and it is described by a Swift law. The yield locus is modeled by the anisotropic Hill48 criterion. A comparison is made between the identification of the Hill48 parameters based on the one hand on the Lankford coefficients [1] and on the inverse modeling of a biaxial tensile test on the other hand [less ▲]

Detailed reference viewed: 37 (1 ULg)
Full Text
Peer Reviewed
See detailIdentification of yield locus parameters of metals using inverse modeling and full field DIC
Lecompte, D.; Cooreman, S.; Sol, H. et al

in Proceedings of the 7th national congress on theoretical and applied mechanics (2006)

The basic principle of the inverse modeling procedure as it is used for parameter identification is the generation of a complex and heterogeneous deformation field that contains as much information as ... [more ▼]

The basic principle of the inverse modeling procedure as it is used for parameter identification is the generation of a complex and heterogeneous deformation field that contains as much information as possible about the parameters to be identified. One way of obtaining such a non-homogeneous deformation is by making the geometry of the specimen less regular. Another possibility is to make the loading conditions more complex. In this paper both options are actually combined by using the concept of a biaxial tensile test on a perforated cruciform specimen. In the present paper, the work hardening of the material is assumed to be isotropic and it is described by a Swift law. The yield locus is modeled by the anisotropic Hill48 criterion. The optimization technique used is a constrained gradient based Newton-type routine, which means that in every iteration step, a sensitivity calculation has to be performed in order to indicate the direction in which the parameters are to be optimized. The functional to be minimized is a least-squares expression of the discrepancy between the measured and the simulated strain fields at a certain load. The numerical routines as well as the identification results of the different parameters, based on simulated strain fields, are discussed. [less ▲]

Detailed reference viewed: 39 (1 ULg)
Full Text
Peer Reviewed
See detailIdentification of hardening behavior using inverse modeling and image correlation
Lecompte, D.; Cooreman, S.; Sol, H. et al

in Proceedings of the SEM annual conference and exposition 2006 (2006)

The basic principle of an inverse modeling procedure as it is used for parameter identification, is the generation of a complex and heterogeneous deformation field that contains as much information as ... [more ▼]

The basic principle of an inverse modeling procedure as it is used for parameter identification, is the generation of a complex and heterogeneous deformation field that contains as much information as possible about the parameters to be identified. One way of obtaining such a non-homogeneous deformation is by making the geometry of the specimen less regular. Another possibility is to make the loading conditions more complex. In this paper both options are actually combined by using a biaxial tensile test on a cruciform specimen in order to identify the parameters of a Swift isotropic hardening law. The yield criterion is modeled by the isotropic Von Mises criterion. The optimization technique used is a constrained gradient based Newton-type routine, which means that in every iteration step, a sensitivity calculation has to be performed in order to indicate the direction in which the parameters are to be optimized. The functional to be minimized is a least-squares expression of the discrepancy between the measured and the simulated strain fields at a certain load. The numerical routines as well as the identification results, based on simulated strain fields, are discussed. [less ▲]

Detailed reference viewed: 34 (2 ULg)
Full Text
Peer Reviewed
See detailA phenomenological model to simulate mechanical tests on ultrafine-grained aluminium produced by ECAE
Diouf, Boubakar; El Houdaigui, Fouad; Poortmans, S. et al

in Mota Soares, C. A. (Ed.) Proceedings of the III European Conference on Computational Mechanics Solids (ECCM III) (2006)

Results of FEM simulations predicting the mechanical behavior at room temperature of test specimens of ultrafine-grained aluminum produced by ECAE are presented. The constitutive law is either based on a ... [more ▼]

Results of FEM simulations predicting the mechanical behavior at room temperature of test specimens of ultrafine-grained aluminum produced by ECAE are presented. The constitutive law is either based on a Hill model or on the Minty micro-macro model and coupled with an isotropic hardening law and/or kinematic hardening law. The yield locus shape, its size and its position during tension, compression and torsion tests have been studied. Initial texture measurements allow the identification of a constitutive law based on a set of representative crystals and crystal plasticity approach using a Full- Constraint Taylor model. Finite element simulations using the previous constitutive laws are compared with experimental investigations. The results show that applying an initial back stress identified by tensile and compression tests to the yield locus predicts the initial flow stress in torsion test. The Minty micro-macro model coupled with a Voce type hardening model gives a good agreement with experimental results for the prediction of the shape at different stages of deformation of a compressed test specimen. The simulation of tensile tests underline the need of inverse modeling as, due to the test specimen shape, the test is far from being homogeneous. The link between test specimen length and the necking appearance is studied. [less ▲]

Detailed reference viewed: 23 (5 ULg)
Full Text
Peer Reviewed
See detailAn FEM-aided investigation of the deformation during single point incremental forming
He, S.; Van Bael, A.; Van Houtte, P. et al

in Modelling & Simulation in Materials Science & Engineering (2006)

Incremental forming is an innovative and flexible sheet metal forming technology for small batch production and prototyping, which does not require any dedicated die or punch to form a complex shape. This ... [more ▼]

Incremental forming is an innovative and flexible sheet metal forming technology for small batch production and prototyping, which does not require any dedicated die or punch to form a complex shape. This paper investigates the process of single point incremental forming of an aluminium cone both experimentally and numerically. Finite element models are established to simulate the process. The output of the simulation is given in terms of final geometry, the thickness profile of the product and the strain history and distribution during the deformation. Comparison between the simulation results and the experimental data is made. [less ▲]

Detailed reference viewed: 40 (1 ULg)
Full Text
Peer Reviewed
See detailFast method to predict an earing profile based on Lankford coefficients and yield locus
Lelotte, Thomas; Duchene, Laurent ULg; Habraken, Anne ULg

in Mota Soares, C. A. (Ed.) Proceedings of the III European Conference on Computational Mechanics Solids (ECCM III) (2006)

This paper compares three methods to determine the earing profile that appears during the deep-drawing test of a circular steel sheet. Three steel grades will be studied. The first method is an ... [more ▼]

This paper compares three methods to determine the earing profile that appears during the deep-drawing test of a circular steel sheet. Three steel grades will be studied. The first method is an experimental test made by a hydraulic press. The second one is a finite ele-ment method (FEM) deep-drawing simulation using a micro-macro texture based constitutive law. The last one directly determines the general aspect of the earing profile from the yield locus which is computed from the initial texture. The goal of this study is to validate the last approach. So, an earing profile prediction can quickly be obtained just from material’s tex-ture. [less ▲]

Detailed reference viewed: 50 (6 ULg)
Full Text
Peer Reviewed
See detailDevelopment and performance assessment of an improved 8-node mixed type FEM element
Duchene, Laurent ULg; de Montleau, P.; Habraken, Anne ULg

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

Several finite element (FE) simulations were investigated using a recently developed mixed type element: the BWD3D. The main formulation of the element is largely described, with particular focus on the ... [more ▼]

Several finite element (FE) simulations were investigated using a recently developed mixed type element: the BWD3D. The main formulation of the element is largely described, with particular focus on the shear locking treatment. The formulation of the former BLZ3D element is also presented for comparison. The examples investigated in the present study were beam bending, large strain torsion, incremental forming and deep drawing .The numerical results obtained with both elements were compared to experiments. [less ▲]

Detailed reference viewed: 44 (9 ULg)
Full Text
Peer Reviewed
See detailCharacterization of Duplex steel Uranus 76N during deformation and heat treatment
Lecomte-Beckers, Jacqueline ULg; Moureaux, P.; Carton, Marc ULg et al

in Physica Status Solidi A. Applications and Materials Science (2006), 203(15), 3651-3664

Duplex Uranus 76N is characterized by metallography, thermal and mechanical analysis. The investigation shows that the microstructure of such a Duplex strongly depends on the cooling conditions ... [more ▼]

Duplex Uranus 76N is characterized by metallography, thermal and mechanical analysis. The investigation shows that the microstructure of such a Duplex strongly depends on the cooling conditions determining the quantity of austenite formed in the ferrite matrix. Numerical simulations of 76N behavior during the rolling process and service life require the knowledge of the recrystallization state during rolling steps at high temperature, thermal parameters such as dilatation, density, specific heat, thermal diffusivity, thermal conductivity and mechanical constitutive laws. These material parameters are determined and presented in this study. [less ▲]

Detailed reference viewed: 68 (4 ULg)
Full Text
Peer Reviewed
See detailQuality assessment of speckle patterns for digital image correlation
Lecompte, D.; Smits, A.; Bossuyt, Sven et al

in Optics & Lasers in Engineering (2006), 44(11), 1132-1145

Digital image correlation (DIC) is an optical–numerical full-field displacement measuring technique, which is nowadays widely used in the domain of experimental mechanics. The technique is based on a ... [more ▼]

Digital image correlation (DIC) is an optical–numerical full-field displacement measuring technique, which is nowadays widely used in the domain of experimental mechanics. The technique is based on a comparison between pictures taken during loading of an object. For an optimal use of the method, the object of interest has to be covered with painted speckles. In the present paper, a comparison is made between three different speckle patterns originated by the same reference speckle pattern. A method is presented for the determination of the speckle size distribution of the speckle patterns, using image morphology. The images of the speckle patterns are numerically deformed based on a finite element simulation. Subsequently, the displacements are measured with DIC-software and compared to the imposed ones. It is shown that the size of the speckles combined with the size of the used pixel subset clearly influences the accuracy of the measured displacements. [less ▲]

Detailed reference viewed: 164 (1 ULg)
Full Text
Peer Reviewed
See detailA 2.5 D finite element model for bending and straightening in continuous casting of steel slabs
Pascon, Frédéric ULg; Cescotto, Serge ULg; Habraken, Anne ULg

in International Journal for Numerical Methods in Engineering (2006), (68), 125-149

This paper presents a bi-dimensional slice model of the continuous casting process developed to focus on the risk of transverse cracking during bending and straightening of steel slabs. The model is based ... [more ▼]

This paper presents a bi-dimensional slice model of the continuous casting process developed to focus on the risk of transverse cracking during bending and straightening of steel slabs. The model is based on the finite element method and it integrates both thermal and mechanical aspects: temperature evolution, solidification, stress and strain developments. Generalized plain strain conditions are applied in the casting direction, allowing taking account of the extraction force applied to the slab as well as strains in this direction. The model also includes an original solution to counteract the generally wrong modelling of slab bulging with such slice models. The model has been applied to an industrial case of slab casting. Some numerical results illustrate the accuracy of the model compared to results of other models, measurements and observations on the caster. Transverse cracks are predicted to be the most likely to occur at the edge on the upper face, at the end of straightening of the slab. This is due to the combination of low ductility of the material with tensile stress and elongation in the casting direction in the straightening zone. This conclusion has been confirmed by the examination of slabs that present transverse cracks. [less ▲]

Detailed reference viewed: 109 (1 ULg)
Peer Reviewed
See detailCaracterizacion del comportamiento elasto-plastico de placas metalicas
Flores, Paulo; Habraken, Anne ULg

(2006)

Detailed reference viewed: 31 (10 ULg)
Full Text
Peer Reviewed
See detailEffect of FEM choices in the modelling of incremental forming of aluminium sheets
He, S.; Van Bael, A.; Van Houtte, P. et al

in Banabic, D. (Ed.) Proceedings of the 8th ESAFORM Conference on Material Forming (2005)

This paper investigates the process of single point incremental forming of an aluminium cone with a 50-degree wall angle. Finite element (FE) models are established to simulate the process. Different FE ... [more ▼]

This paper investigates the process of single point incremental forming of an aluminium cone with a 50-degree wall angle. Finite element (FE) models are established to simulate the process. Different FE packages have been used. Various aspects associated with the numerical choices as well as the material and process parameters have been studied. The final geometry and the reaction forces are presented as the results of the simulations. Comparison between the simulation results and the experimental data is also made. [less ▲]

Detailed reference viewed: 101 (5 ULg)
Full Text
Peer Reviewed
See detailModelling of semi-continuous casting of cupro-nickel alloys
Pascon, Frédéric ULg; Pecquet, Etienne ULg; Zhang, Lihong ULg et al

in Papadrakakis, M.; Onate, E.; Schrefler, B. (Eds.) Proceedings of the International Conference on Computational Methods for Coupled Problems in Science and Engineering (2005)

This research developed at University of Liege aims to optimize the complete semi-continuous casting process at LBP Company, a producer of copper-nickel alloys (or cupro-nickels). The process consists in ... [more ▼]

This research developed at University of Liege aims to optimize the complete semi-continuous casting process at LBP Company, a producer of copper-nickel alloys (or cupro-nickels). The process consists in vertical casting of 7m long ingots. Some problems recurrently occur during casting process: formation of oscillations (wave length of about 500 mm), unsuitable concave cross-sections or internal cracks. In order to reduce the occurrence of such defects and to better understand their formation, we have been asked to develop a finite element model. The research focuses on two main topics: identification of material properties through laboratory tests and literature survey and the development of the numerical tool. The laboratory tests provide thermal and mechanical properties of the ingot and the mould, as well as heat transfer coefficients between the ingot and its surroundings (mould, air and water). These parameters are required for the numerical simulations of the process. In the second part of the research, numerical calculations have been performed using finite element method. Two types of 2D models have already been studied: horizontal slice and vertical slice. This first choice has been guided by the high coupling between thermal and mechanical aspects of the problem, leading to highly complex systems of equations and subsequent long CPU times. However, due to the limitations of such 2D models, a 3D formulation has then been considered and it is still in progress. [less ▲]

Detailed reference viewed: 69 (7 ULg)
Full Text
Peer Reviewed
See detailExperimental validation of the finite element simulation of the first stroke in single point incremental forming
Watzeels, Ken; Tunckol, Y.; Henrard, Christophe ULg et al

in Banabic, D. (Ed.) Proceedings of the 8th ESAFORM Conference on Material Forming (2005)

Single-point incremental forming (SPIF) is a sheet metal forming technique that has gained particular interest in rapid prototyping and small volume production. The study of the underlying forming ... [more ▼]

Single-point incremental forming (SPIF) is a sheet metal forming technique that has gained particular interest in rapid prototyping and small volume production. The study of the underlying forming mechanisms is supported by new developments in finite element simulations and experimental full field strain measurements. This article aims to describe the possibilities and difficulties encountered during validation of finite element predictions of the incremental forming process. The drawing of a straight line into a metal plate was selected as a first test case for this kind of validation. Results of both finite element simulation and experimental work will be discussed. [less ▲]

Detailed reference viewed: 66 (4 ULg)
Full Text
Peer Reviewed
See detailDevelopment of a contact model adapted to incremental forming
Henrard, Christophe ULg; Bouffioux, Chantal ULg; Godinas, A. et al

in Banabic, D. (Ed.) Proceedings of the 8th ESAFORM Conference on Material Forming (2005)

The objective of this article is to present the development of a new method for taking into account the contact between the tool and the blank during incremental forming. First, the need for such a model ... [more ▼]

The objective of this article is to present the development of a new method for taking into account the contact between the tool and the blank during incremental forming. First, the need for such a model is justified. Then, the basic features of the adapted dynamic explicit scheme are presented, followed by the new algorithms proposed and their programming. Finally, some conclusions and perspectives are drawn. [less ▲]

Detailed reference viewed: 59 (6 ULg)
Full Text
Peer Reviewed
See detailAxes rotation during simple shear test: Measurement and predictions
Lelotte, Thomas; Gerday, Anne-Françoise ULg; Flores, Paulo et al

in Oñate, E.; Owen, D. R. J. (Eds.) Proceedings of the VIII International Conference on Computational Plasticity (COMPLAS VIII) (2005)

For a simple shear test, the finite element (FE) local frame, that stays orthogonal, does not follow the anisotropic material frame. To study this effect, FE simulations have been compared with ... [more ▼]

For a simple shear test, the finite element (FE) local frame, that stays orthogonal, does not follow the anisotropic material frame. To study this effect, FE simulations have been compared with experimental results (optical and texture measurements) and it was shown that it is necessary to take into account the effect of texture updating for local axes rotation. [less ▲]

Detailed reference viewed: 42 (19 ULg)