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Bob Svendsen - One of the best experts on this subject based on the ideXlab platform.

  • modeling and finite element simulation of Loading Path dependent hardening in sheet metals during forming
    International Journal of Plasticity, 2014
    Co-Authors: Till Clausmeyer, Alper Guner, Ahmet Erman Tekkaya, Vladislav Levkovitch, Bob Svendsen
    Abstract:

    Abstract A recent material model considering the evolution of plastic anisotropy in interstitial free steels is validated for the forming process of the channel die, a complex part. In the model the evolution of the intra-granular microstructure is represented by tensor-valued internal variables. The model accounts for the cross hardening behavior observed in rheological tests of interstitial free steels. A novel cross hardening indicator which is directly derived from the constitutive model is proposed. This cross hardening indicator is a quantitative measure for the occurrence of cross hardening in the forming process of complex parts. A correlation between the occurrence of cross hardening and larger values of the stored (elastic) energy is observed. The influence of cross hardening on the forming process is investigated, in particular, the drawing forces and the geometric deviations due to springback. The influence of cross hardening on the forming process of the channel die geometry is small. The influence of cross hardening on the more complex S-Rail geometry is larger due to larger plastic deformation and more severe Loading Path changes. The concept of the proposed transient hardening indicator should be applicable to other models for the evolution of plastic anisotropy. A possible use of the cross hardening indicator would be the efficient choice of the material model in the context of sheet metal forming simulations.

  • on the modeling of hardening in metals during non proportional Loading
    International Journal of Plasticity, 2008
    Co-Authors: J Wang, Vladislav Levkovitch, Bob Svendsen, F Reusch, J Huetink, M Van Riel
    Abstract:

    The purpose of the current work is the formulation and initial application of a phenomenological model for hardening effects in metals subject to non-proportional Loading histories characterized by one or more Loading-Path changes. This model is closely related to the incremental model of Teodosiu and Hu [Teodosiu, C., Hu, Z., 1995. Evolution of the intragranular microstructure at moderate and large strains: modelling and computational significance. In: Shen, S.F., Dawson, P.R. (Eds.), Simulation of Materials Processing: Theory, Methods and Applications. Balkema, Rotterdam, pp. 173–182; Teodosiu, C., Hu, Z., 1998. Microstructure in the continuum modelling of plastic anisotropy. In: Proceedings of 19th Riso International Symposium on Material’s Science: Modelling of Structure and Mechanics of Materials from Microscale to Product. Riso National Laboratory, Roskilde, Denmark, pp. 149–168]. Like their model, the current model captures in particular hardening stagnation after a load reversal as well as cross-hardening after orthogonal Loading-Path changes. On the other hand, the two models predict qualitatively different behavior during Loading-Path changes which take place purely in the inelastic range. Such is the case for example during orthogonal Loading-Path changes from uniaxial tension to simple shear without release, or during monotonic simple shear, or during deep-drawing. As shown by the experimental results reported on in the current work for the mild steel DC06, significant cross-hardening can occur during continuous orthogonal Loading-Path changes. Beyond this, the current model accounts in an approximate way for the possible effects of texture development on the material behavior with the help of the plastic spin. After investigating the behavior of the current model for various ideal two-stage Loading histories (e.g., tension-shear), the current work ends with a comparison of standard combined hardening and current approaches in the context of the simulation of internal stress development and residual stresses during deep-drawing and the resultant springback after ring-splitting

Pierre-olivier Bouchard - One of the best experts on this subject based on the ideXlab platform.

  • A new finite element approach for modelling ductile damage void nucleation and growth—analysis of Loading Path effect on damage mechanisms
    Modelling and Simulation in Materials Science and Engineering, 2014
    Co-Authors: Emile Roux, Modesar Shakoor, Marc Bernacki, Pierre-olivier Bouchard
    Abstract:

    A two-dimensional finite element (FE) model is presented to model the nucleation and void growth stages in ductile damage phenomena on the microstructure scale. This model is based on a level-set (LS) method coupled with an advanced re-meshing strategy. Both nucleation modes (interface debonding and inclusion fracture) are modelled through the introduction of micro-voids according to stress-based criteria. The LS method and mesh adaptation are used to accommodate the topology modification of the microstructure and to model multiple void nucleation and growth for different Loading Paths. The enhanced FE model is adopted to analyse the key features of the damage mechanisms on the micro-scale. The effects of inclusion orientation and of a complex Loading Path on nucleation and void growth are addressed. Good agreement is found with available experimental and numerical data found in the literature. The results exhibit that the Loading Path is a key point in damage growth. The proposed FE framework is an efficient technique to study damage phenomena on both simple and realistic microstructures. In the future, such an approach can be used to calibrate macroscopic ductile damage models for a complex Loading Path.

  • a new finite element approach for modelling ductile damage void nucleation and growth analysis of Loading Path effect on damage mechanisms
    Modelling and Simulation in Materials Science and Engineering, 2014
    Co-Authors: Emile Roux, Modesar Shakoor, Marc Bernacki, Pierre-olivier Bouchard
    Abstract:

    A two-dimensional finite element (FE) model is presented to model the nucleation and void growth stages in ductile damage phenomena on the microstructure scale. This model is based on a level-set (LS) method coupled with an advanced re-meshing strategy. Both nucleation modes (interface debonding and inclusion fracture) are modelled through the introduction of micro-voids according to stress-based criteria. The LS method and mesh adaptation are used to accommodate the topology modification of the microstructure and to model multiple void nucleation and growth for different Loading Paths. The enhanced FE model is adopted to analyse the key features of the damage mechanisms on the micro-scale. The effects of inclusion orientation and of a complex Loading Path on nucleation and void growth are addressed. Good agreement is found with available experimental and numerical data found in the literature. The results exhibit that the Loading Path is a key point in damage growth. The proposed FE framework is an efficient technique to study damage phenomena on both simple and realistic microstructures. In the future, such an approach can be used to calibrate macroscopic ductile damage models for a complex Loading Path.

Suzanne Degallaix - One of the best experts on this subject based on the ideXlab platform.

  • Yield Surface and Complex Loading Path Simulation of a Duplex Stainless Steel Using a Bi-Phase Polycrystalline Model
    Materials Science Forum, 2008
    Co-Authors: Pierre Evrard, Véronique Aubin, Suzanne Degallaix, Djimedo Kondo
    Abstract:

    In order to model the elasto-viscoplastic behaviour of an austenitic-ferritic stainless steel, the model initially developed by Cailletaud-Pilvin [1] [2] and used for modeling single-phase polycrystalline steel is extended in order to take into account the bi-phased character of a duplex steel. Two concentration laws and two local constitutive laws, based on the crystallographic slips and the dislocation densities, are thus simultaneously considered. The model parameters are identified by an inverse method. Simple tests among which tension test at constant strain rate and at different strain rates and uniaxial tension-compression test are used during the identification step. The predictive capabilities of the polycrystalline model are tested for non-proportional Loading Paths. It is shown that the model reproduces the over-hardening experimentally observed for this kind of Loading Paths. Then, yield surfaces are simulated during a uniaxial tension-compression test: it is shown that the distortion (i.e. plastic anisotropy induced by Loading Path) is correctly described.

  • Load History in Fatigue: Effect of Strain Amplitude and Loading Path
    Journal of ASTM International, 2004
    Co-Authors: Véronique Aubin, Philippe Quaegebeur, Suzanne Degallaix
    Abstract:

    The low-cycle fatigue behavior of a duplex stainless steel, 60 % a - 40 % y, is studied under tension-compression/torsion Loading at room temperature and under strain control. It is shown that the duplex stainless steel has an isotropic behavior under cyclic proportional Loading. The Loading Path induces an extra-hardening on cyclic hardening of duplex stainless steel but lower than that on austenitic stainless steels. The effect of Loading history is studied in terms of strain amplitude, mean strain, and Loading Path. It is shown that only histories in strain amplitude and Loading Path have an effect on the stabilized stress.

  • Cyclic plasticity of a duplex stainless steel under non-proportional Loading
    Material Sciences and Engineering, 2003
    Co-Authors: Véronique Aubin, Philippe Quaegebeur, Suzanne Degallaix
    Abstract:

    The low-cycle fatigue behavior of a duplex stainless steel, 60 % ferrite - 40 % austenite, is studied under tension-compression/torsion Loading at room temperature. The influences of Loading direction and Loading Path are analyzed. It is shown that the duplex stainless steel has an isotropic behavior under tension-torsion Loading in monotonic as well as in cyclic conditions. The Loading Path induces an over-hardening on cyclic hardening of duplex stainless steel, but lower than the one on austenitic stainless steels. The effect of Loading history is studied in terms of strain amplitude, mean strain and Loading Path. It is shown that only histories in strain amplitude and Loading Path have a small effect on the stabilized stress.

J Llorca - One of the best experts on this subject based on the ideXlab platform.

  • influence of the Loading Path on the strength of fiber reinforced composites subjected to transverse compression and shear
    International Journal of Solids and Structures, 2008
    Co-Authors: Essam Totry, Carlos Gonzalez, J Llorca
    Abstract:

    The influence of the Loading Path on the failure locus of a composite lamina subjected to transverse compression and out-of-plane shear is analyzed through computational micromechanics. This is carried out using the finite element simulation of a representative volume element of the microstructure, which takes into account explicitly fiber and matrix spatial distribution within the lamina. In addition, the actual failure mechanisms (plastic deformation of the matrix and interface decohesion) are included in the simulations through the corresponding constitutive models. Two different interface strength values were chosen to explore the limiting cases of composites with strong or weak interfaces. It was found that failure locus was independent of the Loading Path for the three cases analyzed (pseudo-radial, compression followed by shear and shear followed by compression) in the composites with strong and weak interfaces. This result was attributed to the fact that the dominant failure mechanism in each material was the same in transverse compression and in shear. Failure is also controlled by the same mechanisms under a combination of both stresses and the failure locus depended mainly on the magnitude of the stresses that trigger fracture rather than in the Loading Path to reach the critical condition.

Laurent Daudeville - One of the best experts on this subject based on the ideXlab platform.

  • triaxial behaviour of concrete under high stresses influence of the Loading Path on compaction and limit states
    Cement and Concrete Research, 2008
    Co-Authors: T Gabet, Yann Malecot, Laurent Daudeville
    Abstract:

    The aim of this study is to characterize the behaviour of concrete under high triaxial Loading at levels of confinement and axial stress of the order of the GigaPascal. This study is carried out within a more general scope of understanding concrete behaviour under impact. The studied concrete has properties as close as possible to those used in current construction projects. A triaxial press of high capacity is used to characterize the triaxial behaviour of concrete according to various Loading Paths. Hydrostatic, triaxial, proportional and oedometric tests are performed and show the influence of the Loading Path on the compaction process. The triaxial and proportional tests show the existence of strain limit states, defining a limit states threshold independent from the Loading Path.

  • Triaxial behaviour of concrete under high stresses: Influence of the Loading Path on compaction and limit states
    Cement and Concrete Research, 2008
    Co-Authors: T Gabet, Yann Malecot, Laurent Daudeville
    Abstract:

    The aim of this study is to characterize the behaviour of concrete under high triaxial Loading at levels of confinement and axial stress of the order of the GigaPascal. This study is carried out within a more general scope of understanding concrete behaviour under impact. The studied concrete has properties as close as possible to those used in current construction projects. A triaxial press of high capacity is used to characterize the triaxial behaviour of concrete according to various Loading Paths. Hydrostatic, triaxial, proportional and oedometric tests are performed and show the influence of the Loading Path on the compaction process. The triaxial and proportional tests show the existence of strain limit states, defining a limit states threshold independent from the Loading Path. © 2007 Elsevier Ltd. All rights reserved.