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Eric Maire - One of the best experts on this subject based on the ideXlab platform.

  • Characterization and modeling of void nucleation by Interface Decohesion in dual phase steels
    Scripta Materialia, 2010
    Co-Authors: Caroline Landron, Eric Maire, Olivier Bouaziz, Jérôme Adrien
    Abstract:

    In situ tensile tests have been carried out during X-ray microtomography imaging of dual phase steels. Void nucleation has been quantified as a function of strain and triaxiality using the obtained three-dimensional images. The Argon criterion of Decohesion has been used in a model for nucleation in the case where martensite plays the role of inclusions. This criterion has been modified to include the local stress field and the effect of kinematic hardening present in such a heterogeneous material.

  • Characterization and modeling of void nucleation by Interface Decohesion in dual phase steels
    Scripta Materialia, 2010
    Co-Authors: Caroline Landron, Eric Maire, Olivier Bouaziz, Jérôme Adrien
    Abstract:

    International audienceIn situ tensile tests have been carried out during X-ray microtomography imaging of dual phase steels. Void nucleation has been quantified as a function of strain and triaxiality using the obtained three-dimensional images. The Argon criterion of Decohesion has been used in a model for nucleation in the case where martensite plays the role of inclusions. This criterion has been modified to include the local stress field and the effect of kinematic hardening present in such a heterogeneous material

  • Damage initiation and growth in metals. Comparison between modelling and tomography experiments
    Journal of the Mechanics and Physics of Solids, 2005
    Co-Authors: Eric Maire, Laurent Babout, Cyril Bordreuil, Jean-claude Boyer
    Abstract:

    Abstract Damage in heterogeneous model materials was measured using high-resolution X-ray absorption tomography. The material consisted of an aluminium matrix containing 1% and 4% of spherical ceramic particles acting as nucleation sites for an Interface Decohesion mechanism of damage. The damage initiation stage was quantified using the global population of particles in the 4% material. A strain path change experiment was then applied to the 1% material. The sample was first deformed in tension in order to create elongated cavities and then compressed at 45 ∘ to rotate and close these cavities. The results of a model based on the Rice and Tracey approach accounting for the presence of particles inside the cavities and calculating their rotation with assuming a linear hardening plastic behaviour of the matrix were compared with the observations. The model was modified to account for the damage initiation phase. It was shown to give a good global prediction of the void volume fraction provided that the physical, mechanical and morphological information are corresponding in the experimental and the model cases. The cavity rotation experiment was also shown to compare well with the calculation although only one cavity was sufficiently opened after compression to allow the comparison.

  • on the competition between particle fracture and particle Decohesion in metal matrix composites
    Acta Materialia, 2004
    Co-Authors: Laurent Babout, Eric Maire, Yves Bréchet, Roger Fougères
    Abstract:

    A simple model for describing the competition between Interface Decohesion and particle cracking as the elementary damage nucleation mechanisms in heterogeneous materials is proposed. It allows to rationalise the influence of the plastic behaviour of the ductile matrix and of the interfacial strength. The model is applied to analyse the dominant damage mechanisms in model composites with aluminium alloys matrix and spherical zirconia/silica reinforcement.

  • Damage initiation in model metallic materials: X-ray tomography and modelling
    Acta Materialia, 2004
    Co-Authors: Laurent Babout, Eric Maire, Roger Fougères
    Abstract:

    Effects of matrix elastoplastic properties and reinforcement volume fraction on damage initiation in model heterogeneous metals have been studied using in situ tensile tests coupled with high resolution X-ray tomography. The materials consisted in two kinds of aluminium matrices (commercially pure Al and Al2124 alloy) reinforced by 4 volp.c. or 20 volp.c. of spherical hard ceramic particles. The main damage mechanisms were found to change from particle/matrix Interface Decohesion to particle cracking as the matrix got harder. Quantitative analyses of experimental observations have been performed using the three dimensional images. These measurements were linked to a Weibull statistic based on different local mechanical quantities (stress, strain or energy) calculated by Finite Element in the particle or at the particle/matrix Interface. The results obtained for particle cracking confirmed that this damage mechanism is intrinsic to the chosen ceramic reinforcement and the theoretical approach allowed to determine mechanical parameters such as the particle critical stress.

Thomas Pardoen - One of the best experts on this subject based on the ideXlab platform.

  • Damage and fracture of dual-phase steels: Influence of martensite volume fraction
    Materials Science and Engineering: A, 2015
    Co-Authors: Qingquan Lai, Yves Bréchet, Olivier Bouaziz, Mohamed Gouné, L. Brassart, Marc Verdier, Guillaume Parry, Astrid Perlade, Thomas Pardoen
    Abstract:

    The influence of the martensite volume fraction (Vm) on the damage and fracture behavior of dual-phase steels was studied by combining experiments and micromechanical modeling. A transition in the dominating damage mechanism is observed when varying Vm. Martensite fracture dominates the void nucleation process at high Vm, while Interface Decohesion prevails at low Vm. Damage accumulation accelerates when Vm increases, resulting in a decrease of the fracture strain. Brittle fracture areas are observed in uniaxial tensile specimens for a sufficiently high Vm. The damage mechanisms and evolution are rationalized using a micromechanical analysis based on periodic finite element cell calculations. The results show that Vm is a key factor for controlling the balance between strength and fracture resistance.

  • Damage and fracture of dual-phase steels: Influence of martensite volume fraction
    Materials Science and Engineering: A, 2015
    Co-Authors: Qingquan Lai, Yves Bréchet, Olivier Bouaziz, Mohamed Gouné, L. Brassart, Marc Verdier, Guillaume Parry, Astrid Perlade, Thomas Pardoen
    Abstract:

    International audienceThe influence of the martensite volume fraction (Vm) on the damage and fracture behavior of dual-phase steels was studied by combining experiments and micromechanical modeling. A transition in the dominating damage mechanism is observed when varying Vm. Martensite fracture dominates the void nucleation process at high Vm, while Interface Decohesion prevails at low Vm. Damage accumulation accelerates when Vm increases, resulting in a decrease of the fracture strain. Brittle fracture areas are observed in uniaxial tensile specimens for a sufficiently high Vm. The damage mechanisms and evolution are rationalized using a micromechanical analysis based on periodic finite element cell calculations. The results show that Vm is a key factor for controlling the balance between strength and fracture resistance

  • Ductile fracture initiated by Interface nucleation in two-phase elastoplastic systems
    Engineering Fracture Mechanics, 2013
    Co-Authors: Kumar Yerra Sampath, Yves Bréchet, Guilhem Martin, M. Véron, Jean-denis Mithieux, Laurent Delannay, Thomas Pardoen
    Abstract:

    Dual-phase materials often show damage nucleation along the Interface between the two phases followed by void growth and coalescence. This failure mechanism is investigated using a microstructure model with both phases deforming plastically according to a physics- based hardening law. The Interface is modeled as a cohesive zone whose constitutive behavior is described by a bi-linear traction–separation law. The Interface is specified with a weak site where damage first initiates representing the presence of a small particle sitting along the Interface. A parametric study is conducted through finite element unit cell calculations to examine the effect of the morphological and rheological factors on the complete ductile damage process. The mismatch of phase properties influences the local stress triaxiality evolution, which, in turn, significantly affects damage nucleation and Interface Decohesion involving possible crack arrest. The strength contrast appears to be more critical than the phase morphology in defining the ductility of typical two-phase metallic systems. The nucleation strain decreases by a factor of 10 when the imposed overall stress triaxiality increases from 0.67 to 2.0.

  • Micromechanics of room and high temperature fracture in 6xxx Al alloys
    Progress in Materials Science, 2007
    Co-Authors: Denis Lassance, Francis Delannay, Damien Fabrègue, Thomas Pardoen
    Abstract:

    The micromechanics of ductile fracture has made enormous progress in recent years. This approach, which was mostly developed in the context of structural integrity analysis, is becoming a key tool for materials scientists to optimize materials fracture properties and forming operations. Micromechanical models allow quantitatively linking fracture properties, microstructure features at multiple lengths scales, and manufacturing conditions. After briefly reviewing the state of the art, this paper illustrates the application of the micromechanics-based methodology by presenting the results of an investigation on the damage resistance of 6xxx Al produced by extrusion. The presence of coarse, elongated, particles is the key microstructural feature affecting the fracture behaviour of 6xxx Al. The detrimental elongated beta-type particles are transformed into rounded alpha-type particles by heat treatment. In situ tensile tests revealed that, at ambient temperature, the alpha particles and the beta particles oriented with the long axis perpendicular to the main loading direction undergo Interface Decohesion, while the beta particles oriented perpendicular to the loading direction break into several fragments. At high temperatures, only Interface Decohesion is observed. Uniaxial tensile tests on notched and smooth round bars were performed on two different alloys, at different temperatures ranging between 20 degrees C and 600 degrees C, under different loading rates, while systematically varying the content in beta versus alpha particles. The ductility increases with decreasing amount of P beta particles, increasing temperature and strain rates, and decreasing stress triaxiality. A viscoplastic extension of the Gurson model has been developed for capturing the complex hierarchy of damage mechanisms, coupled with viscoplastic and stress state effects. Three populations of voids are modelled while accounting for the different void nucleation mechanisms leading to different initial void aspect ratio. Proper modelling of the initial void aspect ratio and of its evolution with void growth was the key to predict the effect of the beta -> alpha conversion on ductility. The void coalescence criterion takes into account the presence of secondary voids resulting from particle fragmentation. The characteristics of particles entering the model were all measured experimentally. The temperature and rate dependent flow properties of the matrix material have been obtained by inverse modelling. The only fitting parameters are the critical stresses for void nucleation. The model is validated by comparing the predictions to the experimental data involving different relative proportion of alpha and beta particles, temperature, loading rate and stress triaxiality. This type of model opens the path for an "alloy by design" strategy which relates end-use properties to upstream manufacturing operations. (C) 2006 Elsevier Ltd. All rights reserved.

Jérôme Adrien - One of the best experts on this subject based on the ideXlab platform.

Olivier Bouaziz - One of the best experts on this subject based on the ideXlab platform.

  • Damage and fracture of dual-phase steels: Influence of martensite volume fraction
    Materials Science and Engineering: A, 2015
    Co-Authors: Qingquan Lai, Yves Bréchet, Olivier Bouaziz, Mohamed Gouné, L. Brassart, Marc Verdier, Guillaume Parry, Astrid Perlade, Thomas Pardoen
    Abstract:

    The influence of the martensite volume fraction (Vm) on the damage and fracture behavior of dual-phase steels was studied by combining experiments and micromechanical modeling. A transition in the dominating damage mechanism is observed when varying Vm. Martensite fracture dominates the void nucleation process at high Vm, while Interface Decohesion prevails at low Vm. Damage accumulation accelerates when Vm increases, resulting in a decrease of the fracture strain. Brittle fracture areas are observed in uniaxial tensile specimens for a sufficiently high Vm. The damage mechanisms and evolution are rationalized using a micromechanical analysis based on periodic finite element cell calculations. The results show that Vm is a key factor for controlling the balance between strength and fracture resistance.

  • Damage and fracture of dual-phase steels: Influence of martensite volume fraction
    Materials Science and Engineering: A, 2015
    Co-Authors: Qingquan Lai, Yves Bréchet, Olivier Bouaziz, Mohamed Gouné, L. Brassart, Marc Verdier, Guillaume Parry, Astrid Perlade, Thomas Pardoen
    Abstract:

    International audienceThe influence of the martensite volume fraction (Vm) on the damage and fracture behavior of dual-phase steels was studied by combining experiments and micromechanical modeling. A transition in the dominating damage mechanism is observed when varying Vm. Martensite fracture dominates the void nucleation process at high Vm, while Interface Decohesion prevails at low Vm. Damage accumulation accelerates when Vm increases, resulting in a decrease of the fracture strain. Brittle fracture areas are observed in uniaxial tensile specimens for a sufficiently high Vm. The damage mechanisms and evolution are rationalized using a micromechanical analysis based on periodic finite element cell calculations. The results show that Vm is a key factor for controlling the balance between strength and fracture resistance

  • Characterization and modeling of void nucleation by Interface Decohesion in dual phase steels
    Scripta Materialia, 2010
    Co-Authors: Caroline Landron, Eric Maire, Olivier Bouaziz, Jérôme Adrien
    Abstract:

    International audienceIn situ tensile tests have been carried out during X-ray microtomography imaging of dual phase steels. Void nucleation has been quantified as a function of strain and triaxiality using the obtained three-dimensional images. The Argon criterion of Decohesion has been used in a model for nucleation in the case where martensite plays the role of inclusions. This criterion has been modified to include the local stress field and the effect of kinematic hardening present in such a heterogeneous material

  • Characterization and modeling of void nucleation by Interface Decohesion in dual phase steels
    Scripta Materialia, 2010
    Co-Authors: Caroline Landron, Eric Maire, Olivier Bouaziz, Jérôme Adrien
    Abstract:

    In situ tensile tests have been carried out during X-ray microtomography imaging of dual phase steels. Void nucleation has been quantified as a function of strain and triaxiality using the obtained three-dimensional images. The Argon criterion of Decohesion has been used in a model for nucleation in the case where martensite plays the role of inclusions. This criterion has been modified to include the local stress field and the effect of kinematic hardening present in such a heterogeneous material.

Mica Grujicic - One of the best experts on this subject based on the ideXlab platform.

  • Effect of martensitic transformation in Ti–15 at % V β-phase particles on lamellar boundary Decohesion in γ-TiAl Part I Derivation of Interface Decohesion potentials
    Journal of Materials Science, 1998
    Co-Authors: Mica Grujicic
    Abstract:

    Molecular statics atomistic simulations of the Ti–15 at% V body-centred cubic (bcc) β-phase–γ-TiAl Interface and γ–γ lamellar boundary Decohesion processes have been carried out to determine the corresponding Decohesion potentials. The potentials are subsequently related to the dislocation structure of the Interface–boundary. Atomic interactions have been represented using the appropriate embedded atom method (EAM) interatomic potential functions. The results obtained show that the Decohesion potential functions are quite complex because they have to account for the instabilities that occur under some modes of Interface Decohesion and for the periodic character of the interfacial shear. Lastly, the use of Decohesion potentials to derive constitutive relations for continuum-type interfacial elements and their implementation in the finite element method are presented. © 1998 Kluwer Academic Publishers

  • effect of martensitic transformation in ti 15 at v β phase particles on lamellar boundary Decohesion in γ tial part i derivation of Interface Decohesion potentials
    Journal of Materials Science, 1998
    Co-Authors: Mica Grujicic, S G Lai
    Abstract:

    Molecular statics atomistic simulations of the Ti–15 at% V body-centred cubic (bcc) β-phase–γ-TiAl Interface and γ–γ lamellar boundary Decohesion processes have been carried out to determine the corresponding Decohesion potentials. The potentials are subsequently related to the dislocation structure of the Interface–boundary. Atomic interactions have been represented using the appropriate embedded atom method (EAM) interatomic potential functions. The results obtained show that the Decohesion potential functions are quite complex because they have to account for the instabilities that occur under some modes of Interface Decohesion and for the periodic character of the interfacial shear. Lastly, the use of Decohesion potentials to derive constitutive relations for continuum-type interfacial elements and their implementation in the finite element method are presented. © 1998 Kluwer Academic Publishers

  • Optimization of 316 stainless steel/alumina functionally graded material for reduction of damage induced by thermal residual stresses
    Materials Science and Engineering: A, 1998
    Co-Authors: Mica Grujicic, Huijuan Zhao
    Abstract:

    Abstract Development of material damage due to the thermal residual stresses in a 316 stainless steel/Al2O3 functionally graded material [FGM] model system during cooling from the processing temperature (900°C) has been analyzed using the commercial finite element package ABAQUS. Specifically, the effect of the material concentration profile of a 316 stainless steel/Al2O3 graded layer between the pure 316 stainless steel and pure Al2O3 regions on redistribution and reduction of thermal residual stresses and material damage has been investigated. For each condition of the interlayer material concentration profile analyzed, the stress and damage reductions have been quantified by comparing the magnitudes of specific stress components and damage parameters (Interface Decohesion, porosity, loss of materials stiffness, etc.) with their counterparts in the nongraded (sharp Interface) 316 stainless steel/Al2O3 case. An optimization analysis of the concentration profile showed that the maximum stress and damage reductions are achieved for nonlinear material concentration profiles represented by the material concentration exponent p=4. In this concentration profile the largest gradient in the material properties is located in the metallic portions of the graded region characterized by the lower values of the Young's modulus and higher plasticity.