Publications

2003

• Constitutive modelling in plasticity
  
  • Stolz Claude
  , 2003.
• Evaluation non destructive de la performance mécanique du cuir
  
  • Luong Minh-Phong
  , 2003. Cette communication propose l'utilisation de la thermographie infrarouge pour évaluer la performance mécanique du cuir, appelée limite d'endommagement acceptable LEA du matériau cuir, facilement obtenue à partir des essais mécaniques couplés avec une scrutation infrarouge non contact, non destructive et en temps réel.
• Principes variationnels et exploitation de mesures de champs en élasticité
  
  • Bonnet Marc
  • Bui Huy Duong
  • Constantinescu Andrei
  Mechanics & Industry, EDP Sciences, 2003, 4 (6), pp.687-697. Il est parfois nécessaire d'identifier certaines grandeurs ou certains paramètres caractérisant des structures ou des matériaux. Cela passe dans tous les cas par l'exploitation de données expérimentales, et les mesures de champs, par la richesse des informations fournies, sont particulièrement bien adaptées à ces objectifs. Cet article a pour objet de présenter certaines techniques d'inversion particulièrement adaptées à l'exploitation de mesures de champs. L'identification de champs de modules élastiques est choisie comme un problème modèle commode pour l'exposition, mais d'autres problèmes d'identification peuvent être abordés dans le même esprit. On s'efforce en particulier de montrer que l'identification par exploitation de mesures de champs ne doit pas nécessairement se faire par la minimisation de critères de type moindres carrés sur les observations, car le fait de disposer de champs mesurés permet de définir d'autres critères, d'une part adaptés à ce type de données et d'autre part obtenus comme conséquences directes des principes variationnels de l'élasticité. Les critères considérés ici sont principalement l'erreur en relation de comportement et l'écart à la réciprocité. Divers exemples d'illustration, de nature purement numérique pour la plupart, sont présentés. (10.1016/j.mecind.2003.09.011)
  DOI : 10.1016/j.mecind.2003.09.011
• Structure and morphology of [icosahedral Al62Cu25.5Fe12.5]100−x[decagonal Al70Co15Ni15]x alloys, for (0∼3 and 5∼10)
  
  • Lei Yi
  • Calvo-Dahlborg M.
  • Dubois J.M
  • Hei Z
  • Weisbecker P.
  • Dong C.
  Journal of Non-Crystalline Solids, Elsevier, 2003, 330 (1-3), pp.39-49. (10.1016/j.jnoncrysol.2003.08.059)
  DOI : 10.1016/j.jnoncrysol.2003.08.059
• Étude micro-mécanique de l'effet de la présence d'amas d'inclusions sur la transition fragile-ductile d'aciers nucléaires.
  
  • Bilger Nicolas
  , 2003. Résumé non disponible
• Cavity identification using 3-D elastodynamic BEM, shape sensitivity and topological derivative
  
  • Bonnet Marc
  • Guzina Bojan B
  • Nintcheu Fata Sylvain
  , 2003, pp.205-212. The problem of mapping underground cavities from surface, i.e. using non-intrusive seismic measurements, is investigated via a regularized boundary integral equation method. With the ground modeled as a three-dimensional uniform, isotropic elastic half-space, the inverse analysis of seismic waves scattered by a three-dimensional void is formulated as a task of minimizing a cost function involving the misfit between experimental observations and theoretical (i.e forward) predictions. This conventional choice of setting is dictated by the very high computational cost of solving the forward elastodynamic scattering problem, which makes e.g. global search strategies infeasible. For an accurate treatment of the gradient search technique employed to solve the inverse problem, derivatives of the predictive boundary element model with respect to the cavity parameters are evaluated using an adjoint problem approach. Here as in most situations where conventional descent methods (here the quasi-Newton algorithm with BFGS formula) are used, results depend on the choice of initial guess and occasional lack of convergence occurs. This has prompted the authors to investigate the use of topological derivative as a tool for preliminary probing. The topological derivative field is computed via a relatively inexpensive procedure, and appears to yield useful indications as to the topology and approximate location of the cavity system. Numerical examples are included to illustrate the effectiveness of the various steps developed so far. (10.1142/9789812702593_0022)
  DOI : 10.1142/9789812702593_0022
• Détermination de la réponse asymptotique d'une structure anélastique soumise à un chargement thermomécanique cyclique.
  
  • Pommier Benjamin
  , 2003. Dans le cadre du dimensionnement à la fatigue thermomécanique des culasses automobiles, nous proposons une méthode de simulation des structures soumises à des chargements cycliques. Cette méthode, alternative aux méthodes classiques (comme la méthode incrémentale) permet de résoudre des problèmes thermomécaniques cycliques non-linéaires. Il s'agit d'une Méthode Cyclique Directe qui consiste à rechercher directement la solution asymptotique d'une structure anélastique soumise à un chargement thermomécanique périodique, sans suivre l'histoire du chargement. Elle est fondée sur les techniques de grand incrément de temps [Ladevèze et al.], en prenant en compte la périodicité de l'état limite [Nguyen et al.] et la transformation de Fourier. Cette méthode permet des gains de temps importants pour les structures comprenant un grand nombre de degrés de liberté. Un développement de cette méthode dans une version commerciale d'Abaqus, a permis de montrer la faisabilité de cette approche dans le cas de la simulation d'une culasse.
• A discussion of sensitivity analysis for the identification of poroelastic material parameters
  
  • Constantinescu Andrei
  • Lecampion Brice
  , 2003.
• Modelling attemps to predict fretting fatigue life in turbine components
  
  • Arrieta Hernan
  • Wackers Patrick
  • Van Ky Dang
  • Maitournam Habibou
  • Constantinescu Andrei
  , 2004. Wherever two or more turbine components are in tight contact, Fretting-Fatigue becomes a relevant failure mechanism. Despite of on-going research on Fretting Fatigue, life prediction under fretting conditions continues being a challenge. To analytically predict fretting-fatigue life, key driving factors need to be identified and quantified in mechanical terms (stress and strain). Due to the intrinsic characteristics of contact, stress and strain fields around contact areas evolve with the loading history. They, together with material non-linearity and contact conditions need to be taken into account in order to perform a reliable life prediction. The present paper focuses on identifying the driving factors for fretting damage on blade-disk attachment under real engine conditions. Two-dimensional finite element contact calculations were carried out to quantify the influence of the key factors on mechanical quantities (stress and strain). Special attention was paid to material models and surface interaction (friction coefficient and contact conditions) in order to balance computational effort with result’s accuracy. Finally, the multi-axial fatigue criteria developed by Dang Van and co-workers is used to predict failure. For validation purposes life prediction is compared with experimental results.
• Modèles standards généralisés à convexe fixe en endommagement
  
  • Cimetière Alain
  • Halm Damien
  • Marigo Jean-Jacques
  • Molines Estelle
  Comptes Rendus. Mécanique, Académie des sciences (Paris), 2003, 331 (4), pp.291-294. Un cadre thermodynamique d'écriture de modèles d'endommagement est introduit. Obtenu par l'adjonction de variables internes complémentaires, il s'inscrit dans celui des matériaux standards généralisés pour lesquels le domaine convexe des forces thermodynamiques admissibles est indépendant des variables internes. Il en présente ainsi les avantages. Le modèle de Marigo est replacé dans ce cadre et un autre exemple est donné combinant à la fois écrouissage isotrope et cinématique. (10.1016/S1631-0721(03)00057-3)
  DOI : 10.1016/S1631-0721(03)00057-3
• Stability and bifurcation with moving discontinuities
  
  • Stolz Claude
  • Pradeilles-Duval Rachel-Marie
  , 2003, pp.261-268. The propagation of moving surface inside a body is analysed in the framework of thermodynamics, when the moving surface is associated with an irreversible change of mechanical properties. The thermodynamical force associated to the propagation has the form of an energy release rate. Quasistatic rate boundary value problem is given when the propagation of the interface is governed by a normality rule. Extension to generalised media to study delamination is also investigated. (10.1007/0-387-26261-X_26)
  DOI : 10.1007/0-387-26261-X_26
• A study of cellular structures under impact loading
  
  • Abdennadher Salim
  • Zhao Han
  • Othman Ramzi
  , 2003. This paper presents the effect of inertia of cellular structures under impact loading. Experimental results under static and dynamic loading will be presented for square tubes made of a rate quasi-insensitive material (brass), the dynamic results being obtained using modified split Hopkinson pressure bar technique. The numeric simulation under Ls-dyna of those tests giving similar results will be also presented. Presented experimental, numeric results show that the inertia effect is a dominant factor responsible for the enhancement of crushing strength of cellular structures. (10.1051/jp4:20020733)
  DOI : 10.1051/jp4:20020733
• Modélisation du comportement dynamique d'une courroie de distribution
  
  • Bourgeois M.
  • Thomas J.-J.
  • Stolz Claude
  , 2003, pp.189-196 (tome 2). No abstract provided
• Méthode numérique pour l'identification de cavités enterrées à l'aide de données élastodynamiques
  
  • Bonnet Marc
  • Guzina Bojan B
  • Nintcheu Fata Sylvain
  , 2003, 1, pp.209-216.
• Investigation of hydrogen and creep contributions to the abnormal fatigue cracking of Ti6246 at high Kmax
  
  • Mignot Frédéric
  • Doquet Véronique
  • Sarrazin-Baudoux Christine
  • Petit Jean
  • Raimbault Louis
  , 2003.
• Combined experimental and modelling approaches to the micromechanics of polycrystals and composites
  
  • Bornert Michel
  • Crépin Jérôme
  • Zaoui André
  , 2003.
• Explicit kinetic relation from `first principles
  
  • Truskinovsky L.
  • Vainchtein A.
  , 2003.
• Transmissibilité vibratoire d'un matériau de recyclage
  
  • Luong M. P.
  • Eytard J. C.
  • Khay M.
  • Vinceslas G.
  • Papachristou D.
  , 2003, pp.349-356 (tome 1). No abstract provided
• Safety of salt caverns used for underground storage. Blow out ; mechanical instability ; seepage ; cavern abandonment
  
  • Bérest Pierre
  • Brouard Benoît
  Oil & Gas Science and Technology - Revue d'IFP Energies nouvelles, Institut Français du Pétrole (IFP), 2003, 58, pp.361-384. Thousands of salt caverns (100 in France alone) are being used to store hydrocarbons. This is the safest way to store large quantities of hydrocarbons: salt formations are almost perfectly impermeable, and fire or explosion is impossible underground. However, a small number of accidents (blow-out, product seepage, cavern instability) have occurred in the past. Cavern abandonment is also a concern in some cases. This paper describes several accidents and the lessons that have been drawn from them, leading to considerable improvements in storage design and operation. (10.2516/ogst:2003023)
  DOI : 10.2516/ogst:2003023
• Simulation of stage I fatigue crack gowth in a polycrystal through coupled FEM and discrete dislocation dynamics
  
  • Bertolino Graciela
  • Doquet Véronique
  • Sauzay Maxime
  , 2003. An attempt to model the variability of short crack development in high-cycle fatigue is made by coupling finite element computations of the stresses ahead of a microcrack in a polycrystal with simulations of crack growth along slip planes based on discrete dislocations dynamics. The model predicts a large scatter in growth rates related to the crystallographic disorientations along the crack path. It also describes qualitatively the influence of the mean grain size and the fact that overloads may suppress the endurance limit by allowing arrested cracks to cross the grain boundaries.
• Mobility of lattice defects: discrete and continuum approaches
  
  • Kresse Olga
  • Truskinovsky Lev
  Journal of the Mechanics and Physics of Solids, Elsevier, 2003, 51, pp.1305-1332. In this paper, we study a highly idealized model of a moving lattice defect allowing for an explicit, “first principles” computation of a functional relation between the macroscopic configurational force and the velocity of the defect. The discrete model is purely conservative and contains information only about elasticities of the constitutive elements. The apparent dissipation is due to the presence of microinstabilities and the nonlinearity-induced tunneling of the energy from long to short wavelengths. This type of “radiative damping” is believed to be generic and accounting for a considerable fraction of inelastic irreversibility associated with fracture, plasticity and phase transitions. The paper contains direct comparison of the exact lattice solution with various continuum and quasicontinuum approximations. Despite its simplicity, the model can be used directly for the description of dynamic phase transitions in thin films. (10.1016/S0022-5096(03)00019-X)
  DOI : 10.1016/S0022-5096(03)00019-X
• Activation of diffuse discontinuities and folding of sedimentary layers
  
  • Guiton Martin
  • Leroy Yves
  • Sassi William
  Journal of Geophysical Research : Solid Earth, American Geophysical Union, 2003, 108 (B4), pp.1-20. Folding of sedimentary layers is often accommodated by the opening or sliding of inherited and new discontinuities which are assumed here to be diffuse so that a continuum description applies at the fold scale. The rock rheology is then described with an elastoplasticity model for which the permanent deformation is of simple shear (sliding) or dilation (opening) with respect to specific orientations of the new or inherited diffuse discontinuities. To illustrate the relation between folding and activation of diffuse discontinuities, a three-dimensional layer under compression in the two horizontal directions and sustaining the overburden lithostatic pressure is studied. Cylindrical buckling occurs either before (elastic) or after the diffuse discontinuities have been activated. If buckling is elastic, inherited vertical discontinuities, striking obliquely to the fold geometrical axes, are activated in a sliding mode in the outer arc, leading to a rotation of the principal stress directions. Opening is then detected across new vertical planes striking obliquely to the fold axis. The activation of inherited or new vertical discontinuities can be suppressed if sliding takes place along weak bedding interfaces. Alternatively, early and homogeneous layer-parallel shortening, marked by a reverse fault mode, drastically reduces the critical buckling load compared to the Euler load and modifies the final geometry of buckling which is then more of a circular dome shape. The switching in buckling mode results in the fold limbs in a change from the early reverse fault to a strike-slip fault sliding and to opening across diffuse planes oriented consistently with the final circular structure. (10.1029/2002JB001770)
  DOI : 10.1029/2002JB001770
• A computational basis for elastodynamic cavity identification in a semi-infinite solid
  
  • Nintcheu Fata Sylvain
  • Guzina Bojan B
  • Bonnet Marc
  Computational Mechanics, Springer Verlag, 2003, 32, pp.370-380. The focus of this paper is a computational platform for the non-intrusive, active seismic imaging of subterranean openings by means of an elastodynamic boundary integral equation (BIE) method. On simulating the ground response to steady-state seismic excitation as that of a uniform, semi-infinite elastic solid, solution to the 3D inverse scattering problem is contrived as a task of minimizing the misfit between experimental observations and BIE predictions of the surface ground motion. The forward elastodynamic solution revolves around the use of the half-space Greenrsquos functions, which analytically incorporate the traction-free boundary condition at the ground surface and thus allow the discretization and imaging effort to be focused on the surface of a hidden cavity. For a rigorous approach to the gradient-based minimization employed to resolve the cavity, sensitivities of the trial boundary element model with respect to (geometric) void parameters are evaluated using an adjoint field approach. Details of the computational treatment, including the regularized (i.e. Cauchy principal value-free) boundary integral equations for the primary and adjoint problem, the necessary evaluation of surface displacement gradients and their implementation into a parallel code, are highlighted. Through a suite of numerical examples involving the identification of an ellipsoidal cavity, a parametric study is presented which illustrates the importance of several key parameters on the imaging procedure including the prior information, ldquomeasurementrdquo noise, and the amount of experimental input. (10.1007/s00466-003-0494-4)
  DOI : 10.1007/s00466-003-0494-4
• Nonhydrostatic stabilization of an orthorhombic phase of zirconia
  
  • Fadda Giuseppe
  • Truskinowsky Lev
  • Zanzotto Giovanni
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2003, 68 (13). An explicit polynomial strain-energy function for tetragonal-orthorhombic-monoclinic zirconia (ZrO2), calibrated from the conventional hydrostatic p−T phase diagram, is used to study the effects of nonhydrostatic loading on the phase equilibria in this material. Several representative sections of the phase diagram of ZrO2 in temperature and stress space, containing both triple and critical points, are computed. A new orthorhombic structure of ZrO2 is predicted to be the most stable phase for a variety of experimentally accessible shear loads, in a wide range of temperatures and pressures. (10.1103/PhysRevB.68.134106)
  DOI : 10.1103/PhysRevB.68.134106
• Hydrostatic interaction of a wetting fluid and a circular crack in an elastic material
  
  • Feraille Fresnet Adélaïde
  • Bui Huy Duong
  • Ehrlacher Alain
  Mechanics of Materials, Elsevier, 2003, 35, pp.581-586. This paper focuses on a new analytical solution: the one of the hydrostatic-elastic problem for a wetting fluid inside a 3D penny shaped circular crack in an elastic infinite solid loaded in tension at infinity, when the vapor pressure and the variation of liquid mass can be neglected. With the surface tension phenomena, the liquid is near the crack tip and is generally in tension (negative pressure). (10.1016/S0167-6636(02)00281-8)
  DOI : 10.1016/S0167-6636(02)00281-8