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
• 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
• Mechanical behaviour of polymer nanocomposites: a discrete simulation approach
  
  • Chabert E.
  • Gauthier R.
  • Dendievel R.
  • Chazeau Laurent
  • Cavaille J. Y.
  , 2003. No abstract provided
• 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
• Ondes de surface sous contact unilatéral et frottement de Coulomb
  
  • Nguyen Q. S.
  • Oueslati A.
  , 2003, pp.353-360 (tome 2). No abstract provided
• Identification of behavior by inverse method performed on local deformation, Dislocations plasticity and metal forming
  
  • Hoc T.
  • Crépin Jérôme
  • Zaoui A.
  , 2003, pp.433-435. No abstract provided
• Analyse fréquentielle de la fatigue des structures
  
  • Moumni Ziad
  • Maitournam Habibou
  • Dang Van Ky
  , 2003, pp.191-198.
• An estimate of maximum ground surface motion
  
  • Pecker Alain
  Comptes Rendus. Mécanique, Académie des sciences (Paris), 2003, 331, pp.661-666. The increasing need for probability seismic hazard assessment (PSHA) of critical facilities sometimes leads to unrealistic earthquake scenarios with very high induced ground motions. From a physical standpoint these high motions cannot exist because of the limiting resistance capacity of the soil strata through which the seismic waves travel. A simple analytical model is proposed to estimate a bound to the maximum ground surface acceleration that any soil deposit can transfer. (10.1016/j.crme.2003.08.001)
  DOI : 10.1016/j.crme.2003.08.001
• Influence de la microstructure dans l'initiation de l'endommagement des alliages de zirconium non irradies
  
  • Elbachiri K.
  • Crépin Jérôme
  • Rebeyrolle V.
  • Bretheau T.
  , 2003. No abstract provided
• Influence de la microstructure des alliages de zirconium sur leur sensibilité a la vitesse de déformation et a la température
  
  • Elbachiri K.
  • Crépin Jérôme
  • Rebeyrolle V.
  • Bretheau T.
  , 2003. No abstract provided
• Growth and cellular differentiation: a physical-biochemical conundrum? The example of the hand
  
  • Schwartz Laurent H
  • Maitournam Habibou
  • Stolz C.
  • Steayert J. M.
  • Ho Ba Tho Marie-Christine
  • Halphen Bernard
  Medical Hypotheses, Elsevier, 2003, 61, pp.45-51. Currently, the predominant hypothesis explains cellular differentiation as an essentially genetic intracellular process. The goal of this paper is to suggest that cell growth and differentiation may be, simply, the result of physical and chemical constraints. Bone growth occurs at the level of cartilage conjunction (growth plate) in a zone of lesser constrain. It appears that this growth also induces muscle, tendon, nerve and skin elongation. This cartilage growth by itself seems to explain the elongation of the hand. Growth stops at puberty likely because of feed-back from an increasing muscle load. The ossification (that is differentiation of cartilage into bone) appears to result from the shear stress induced. The study of bone age, obtained by X-ray picture of the hand, shows that ossification of epiphyses is very precise both in time and space. Computer modelization suggests that this ossification occurs where shear stress is greatest. The cartilage which does not ossify (joint, nose, larynx, ear, bronchus, etc.) is not exposed to high shear. Shear stress induces the secretion of extracellular matrix and a change of the biochemical environment of the cell. Precipitation of calcium phosphate, as in ossification, seems related to the alkalosis induced by shear stress. To speak in more general terms, loss of cellular differentiation, as occurs with cancer, can result from a change in the physical–chemical environments. (10.1016/S0306-9877(03)00102-6)
  DOI : 10.1016/S0306-9877(03)00102-6
• Explicit Kinetic Relation from “First Principles”
  
  • Truskinovsky L.
  • Vainchtein A.
  , 2003. We study a fully inertial discrete model of a martensitic phase transition which takes into account interactions of first and second nearest neighbors. Although the model is Hamiltonian at the microscale, it generates a nontrivial macroscopic relation between the velocity of the martensitic phase boundary and the conjugate configurational force. The apparent dissipation is due to the induced radiation of lattice waves carrying energy away from the front. (10.1007/0-387-26261-X_5)
  DOI : 10.1007/0-387-26261-X_5
• Distribution inter et intra-granulaire des déformations élastiques dans un acier charge élastiquement: analyse par diffraction et homogénéisation
  
  • Castelnau O.
  • Letouze N.
  • Crépin Jérôme
  • Caldemaison D.
  • Ceretti M.
  • Brenner R.
  , 2003. No abstract provided
• A shakedown analysis in hardening plasticity
  
  • Nguyen Quoc Son
  Journal of the Mechanics and Physics of Solids, Elsevier, 2003, 51, pp.101-125. The extension of classical shakedown theorems for hardening plasticity is interesting from both theoretical and practical aspects of the theory of plasticity. This problem has been much discussed in the literature. In particular, the model of generalized standard materials gives a convenient framework to derive appropriate results for common models of plasticity with strain-hardening. This paper gives a comprehensive presentation of the subject, in particular on general results which can be obtained in this framework. The extension of the static shakedown theorem to hardening plasticity is presented at first. It leads by min-max duality to the definition of dual static and kinematic safety coefficients in hardening plasticity. Dual static and kinematic approaches are discussed for common models of isotropic hardening, of limited or unlimited kinematic hardening. The kinematic approach also suggests for these models the introduction of a relaxed kinematic coefficient following a method due to Koiter. Some models for soils such as the Cam-clay model are discussed in the same spirit for applications in geomechanics. In particular, new appropriate results concerning the variational expressions of the dual kinematic coefficients are obtained. (10.1016/S0022-5096(02)00058-3)
  DOI : 10.1016/S0022-5096(02)00058-3
• Mechanical constraints on the chronology of fracture activation in folded Devonian sandstone of the western Moroccan Anti-Atlas
  
  • Guiton M. L. E.
  • Sassi W.
  • Leroy Y. M.
  • Gauthier B. D. M.
  Journal of Structural Geology, Elsevier, 2003, 25, pp.1317-1330. The three-dimensional meter-scale fracture networks, observed on exposed folds between the towns of Tata and Akka, western Moroccan Anti-Atlas, consist mostly of planar discontinuities, which are sub-perpendicular to the bedding and partitioned in three main sets. The chronology of their activation is proposed in five stages since the Hercynian orogeny. Stage 1 predates folding and involves the horizontal compression of the Emsian sandstone. It involves fracture set I, composed of systematic joints parallel to the direction of compression. Stages 2–4 correspond to the folding and are marked in the outer-arc by the activation of fracture set II, composed mainly of joints parallel to the fold axial plane. Stage 5 is a regional shear event during which sets I and III, separated by an angle close to 60°, are activated in a conjugate manner. To throw light on the recurrent difficulty in discriminating between activation of inherited and new fractures, an elasto-plastic model is used to construct a stress path in the pervasively fractured medium idealized as a continuum. Each fracture set obeys the Mohr–Coulomb criterion truncated in tension to describe both sliding and opening activations. Finite-element simulations of a simple buckling event accounting for the field fracture sets are presented. It is shown that set I cannot be generated by folding and thus does belong to stage 1. Set II is activated at a later stage of folding than expected from the field interpretation. Set III cannot be activated during stage 2, confirming its role in stage 5. The advantages and limitations of the proposed modeling are finally discussed. (10.1016/S0191-8141(02)00155-4)
  DOI : 10.1016/S0191-8141(02)00155-4
• Caractérisation de la répartition de la déformation dans les matériaux hétérogènes
  
  • Doumalin Pascal
  • Bornert Michel
  • Crépin Jérôme
  Mechanics & Industry, EDP Sciences, 2003, 4, pp.607-617. On présente une méthode originale de caractérisation de la répartition de la déformation dans les matériaux hétérogènes, basée sur l'adaptation des techniques statistiques de caractérisation morphologique par covariance à 2 points aux champs locaux de déformation mesurés par microextensométrie MEB. Elle permet de montrer que le comportement mécanique n'est pas uniquement la conséquence d'interactions très locales entre grains ou domaines de phases voisins, mais résulte aussi de phénomènes à plus grande portée. (10.1016/j.mecind.2003.09.002)
  DOI : 10.1016/j.mecind.2003.09.002