References of "Ben Bettaieb, Mohamed"
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See detailApplication of an Advanced GTN Model
Fansi, Joseph; Habraken, Anne ULg; Balan, Tudor et al

Conference (2012)

The present contribution consists of implementing an advanced GTN damage model as a "User Material subroutine" in the Abaqus FE code. This damage model is based on specific nucleation and growth laws.This ... [more ▼]

The present contribution consists of implementing an advanced GTN damage model as a "User Material subroutine" in the Abaqus FE code. This damage model is based on specific nucleation and growth laws.This model is applied to the prediction of the damage evolution and the stress state in notched specimens made of dual phase steel. By comparing numerical predictions with experimental results based on high-resolution X-ray absorption tomography, the numericalapproach was improved and validated [less ▲]

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See detailAveraging properties for periodic homogenization and large deformation
Ben Bettaieb, Mohamed ULg; Débordes, Olivier; Dogui, Abdelwaheb et al

in International Journal for Multiscale Computational Engineering (2012)

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See detailNumerical modeling of damage evolution of DP steels on the basis of X-ray tomography measurements
Ben Bettaieb, Mohamed ULg; Lemoine, Xavier; Bouaziz, O. et al

in Mechanics of Materials (2011), 43(3), 139-156

In order to couple the damage evolution and the stress state of DP steel grades, a new advanced GTN (Gurson-Tvergaard-Needleman) model was developed and implemented into a finite element code. This model ... [more ▼]

In order to couple the damage evolution and the stress state of DP steel grades, a new advanced GTN (Gurson-Tvergaard-Needleman) model was developed and implemented into a finite element code. This model is an extension of the original one. It takes into account the plastic anisotropy and the mixed (isotropic+ kinematic) hardening of the matrix. Two different methods to compute the void volume fraction were developed and used within the constitutive equations. The first method is new and allows the accurate modeling of the observations of damage initiation and growth in DP steels measured using high-resolution X-ray absorption tomography (Bouaziz et al., 2008; Maire et al., 2008). The second method is classic and assumes the additive decomposition of the total void volume fraction into a nucleation and a growth part. A parametric study is carried out to assess the effect of the kinematic hardening on some mechanical parameters such as the equivalent plastic strain, the triaxiality and the porosity. The numerical predictions are favorably compared to the experimental results. [less ▲]

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See detailMaterial behavior of the hexagonal alpha phase of a titanium alloy identified from nanoindentation tests
Gerday, Anne-Françoise ULg; Ben Bettaieb, Mohamed ULg; Duchene, Laurent ULg et al

in European Journal of Mechanics A : Solids (2011), 30

This article focuses on the numerical modeling of nanoindentation tests performed on the hexagonal a phase of Ti-5553 alloy in order to identify its mechanical behavior. The main goal consists in ... [more ▼]

This article focuses on the numerical modeling of nanoindentation tests performed on the hexagonal a phase of Ti-5553 alloy in order to identify its mechanical behavior. The main goal consists in determining the relative strength of the slip modes in the a phase of Ti-5553. This work was performed using an elastoviscoplastic crystal plasticity-based constitutive law. The difficulties in determining the slip systems that can be activated and their corresponding critical resolved shear stresses (CRSS) are discussed. Numerical predictions are compared to experimental nanoindentation curves. [less ▲]

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See detailNotched Specimens Fracture Prediction with an Advanced GTN Model
Fansi Tchonko, Joseph ULg; Ben Bettaieb, Mohamed ULg; Balan, Tudor et al

in Key Engineering Materials [=KEM] (2011), 488-489

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See detailA finite element analysis of the bending and the bendability of metallic sheets
Ben Bettaieb, Mohamed ULg; Lemoine, Xavier; Bouaziz, O. et al

in International Journal of Material Forming (2011), 4(3), 283-297

The main objective of this paper is to study the bendability of metallic sheets by using the finite element method. In this aim, two variants of an advanced Gurson-Tvergaard-Needleman model [1, 2] are ... [more ▼]

The main objective of this paper is to study the bendability of metallic sheets by using the finite element method. In this aim, two variants of an advanced Gurson-Tvergaard-Needleman model [1, 2] are implemented in the home made FE code LAGAMINE [3, 4] and coupled with the Thomason model to predict the coalescence of voids. This advanced model is an extension of the original one to take into account of the plastic anisotropy and the mixed (isotropic + kinematic) hardening of the matrix. The difference between the two variants is related to the modeling of the damage evolution. As the advanced model is used to study the bending process, its yield function is slightly modified in order to take into account the loadings with negative triaxiality ratios. These present implementations are used to simulate the pure bending process and to predict the bendability of dual phase (DP) steel. The combined effect of an initial geometrical imperfection and damage evolution on the bendability is also studied. [less ▲]

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See detailOn the numerical integration of an advanced Gurson model
Ben Bettaieb, Mohamed ULg; Lemoine, Xavier; Duchene, Laurent ULg et al

in International Journal for Numerical Methods in Engineering (2011), 85(8), 1049-1072

This article is focused on a new extended version of Gurson's model (J. Eng. Mater. Technol. 1977; 99:2–15), its numerical integration scheme and its consistent tangent matrix being within an FE code ... [more ▼]

This article is focused on a new extended version of Gurson's model (J. Eng. Mater. Technol. 1977; 99:2–15), its numerical integration scheme and its consistent tangent matrix being within an FE code. First, this new advanced Gurson model is proposed, which is an extension of the original to take into account plastic anisotropy and mixed (isotropic+kinematic) hardening. In this paper, only the growth phase of cavities is considered (the nucleation of new voids is ignored). Second, a new numerical algorithm for the integration of this new Gurson model is presented. The algorithm is implicit in all variables and is unconditionally stable. This algorithm is generic and could be used for other anisotropic yield functions and other hardening laws. Third, the consistent tangent matrix is computed in an explicit way by exact linearization of the constitutive equations. To check its efficiency and robustness, the proposed integration algorithm is compared, under some simplified assumptions and choices, with the algorithms of Aravas (Int. J. Numer. Meth. Engng 1987; 24:1395–1416) and Kojic (Int. J. Numer. Meth. Engng 2002; 53(12):2701–2720). The performance of the developed consistent modulus, compared to other techniques for the computation of the tangent matrix is assessed. The paper ends with numerical simulations of tensile tests on homogeneous and notched specimens. [less ▲]

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See detailInvestigation of the Efficiency of the Ti555 Compared with TA6V Alloy in the Case of an Aeronautic Application
Ben Bettaieb, Mohamed ULg; Van Hoof, T.; Zhang, Lihong ULg et al

in Proceedings of the 12th World Conference on Titanium (2011)

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See detailInvestigation of the efficiency of the Ti555 compared with TA6V alloy in the case of an aeronautic application
Ben Bettaieb, Mohamed ULg; Van Hoof, T.; Zhang, Lihong ULg et al

in The 12th World Conference on Titanium Ti-2011 (2011)

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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 detailSimulation of bending process of hardening metallic sheets using damage model. Part II: Numerical investigations
Ben Bettaieb, Mohamed ULg; Lemoine, Xavier; Duchene, Laurent ULg et al

in Materials Science & Engineering : A (2010), 528(1), 442-448

In the first part of this paper, the theoretical aspects and the algorithmic developments related to the construction of the PBST (Pure Bending Simulation Tool) were provided. In this second part, this ... [more ▼]

In the first part of this paper, the theoretical aspects and the algorithmic developments related to the construction of the PBST (Pure Bending Simulation Tool) were provided. In this second part, this tool is used to simulate the pure bending process. The sensitivity of the bendability prediction to certain mechanical properties and phenomena (such as initial porosity and hardening parameters) is investigated by means of a parametric study. The efficiency and the performance of this tool (in terms of accuracy and computation time) compared to the FE method are shown through various numerical simulations. [less ▲]

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See detailSimulation of bending process of hardening metallic sheets using damage model. Part I: Theoretical development and numerical implementation.
Ben Bettaieb, Mohamed ULg; Lemoine, Xavier; Duchene, Laurent ULg et al

in Materials Science & Engineering : A (2010), 528(1), 434-441

This paper deals with the pure bending of thin and thick metallic sheets under plane strain condition. Its main objective is to construct an efficient, robust, incremental numerical tool that can be used ... [more ▼]

This paper deals with the pure bending of thin and thick metallic sheets under plane strain condition. Its main objective is to construct an efficient, robust, incremental numerical tool that can be used to simulate the bending process and predict the sheets’ bendability. In this investigation, the material constitutive law describing the mechanical behavior of the sheet is defined by an extended Gurson model. This model generalizes Gurson's original one to account for both plastic anisotropy and mixed (isotropic and kinematic) hardening of the matrix. In this model, only the growth phase of voids was considered (without taking into account nucleation). Here, the extended model was coupled with the kinematics of the pure bending process and with the equilibrium equations, and then implemented in an incremental numerical tool in order to predict the bendability of the sheets studied. This bendability was then verified using two different criteria. Part I of this paper focuses on the constitutive law, fulfillment of the force equilibrium, the thickness evolution and the shift of the neutral fiber, together with a comparison and discussion of the choices made by other authors regarding these parameters. The validation of the model developed in this paper will be carried out in Part II through simulations of the pure bending process. [less ▲]

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See detailEffect of a decrease in sample dimensions on plasticity: application to the micro-forming of nickel
Keller, Clément ULg; Afteni, Mitica; Banu, M. et al

in Steel Research International (2010), 81(9), 1173-1177

The mechanical behavior of polycrystalline nickel is investigated in tension as a function of the dimensions. Experimental tests and finite element simulations with a crystalline plasticity code are ... [more ▼]

The mechanical behavior of polycrystalline nickel is investigated in tension as a function of the dimensions. Experimental tests and finite element simulations with a crystalline plasticity code are carried out for samples with thicknesses ranging between 12.5 μm and 3.2 mm and grain size around 100 μm. Results show three different kinds of behavior depending on the number of grains across the thickness due to the apparition of stress and dislocation density gradients. Bulge tests are then used to study the formability of nickel polycrystals with thickness lower than 400 μm. [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 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 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 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 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 detailStudy of bendability of steel sheets
Ben Bettaieb, Mohamed ULg; Lemoine, Xavier; Duchene, Laurent ULg et al

in Steel Research International (2008), (79/1), 225-232

In the present contribution bending tests are modeled and the bendability of steel sheets is evaluated. Bendability refers to the ratio of the minimum bend radius to the initial sheet thickness at which ... [more ▼]

In the present contribution bending tests are modeled and the bendability of steel sheets is evaluated. Bendability refers to the ratio of the minimum bend radius to the initial sheet thickness at which the bending proc-ess is successfully accomplished [1]. The metallurgic microstructure of the studied sheet consists in two principal phases: a fully dense matrix (which may be itself composed by several metallurgic phases) and spherical voids. For that purpose, the Gurson Tvergaard Needleman law ([2], [3], [4]) is used and significantly modified. The behavior of the fully dense matrix is de-fined by the anisotropic Hill 48 function and the Swift hardening law. The width of the sheet is assumed to be large enough to neglect the transversal strains and the stress component in the thickness direction is also neglected. The bending operation can thus be modelled by a plane strain-plane stress loading. The influence of mechanical pa-rameters such as the initial porosity, the Lankford coefficient and the strain harden-ing exponent on the bendability is studied herein. The failure here is defined by the onset coalescence of neighbour voids and is checked by using Thomason [5], Pardoen [6] and Brunet [7] coalescence models. So the influence of other phenomena (like the shear band development and the localized necking) on the bendability is neglected here. [less ▲]

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