Publications

2000

• Intelligent modelling of woven materials
  
  • Zarka Joseph
  • Doux Thierry
  , 2000.
• Optimal design of a beam with a direct link to CAD
  
  • Zarka J.
  • Hablot J. M.
  , 2000. No abstract provided
• Quelques exemples de vibrations et d'instabilité induites par le frottement
  
  • Nguyen Q. S.
  , 2000. No abstract provided
• Intelligent optimal design of naval structures: is it possible ?
  
  • Zarka J.
  , 2000. No abstract provided
• Percolation mécanique'' : pertinence des modèles classiques en viscoélasticité linéaire et nouvelles approches
  
  • Bornert Michel
  • Aussant F.
  • Zaoui A.
  , 2000. No abstract provided
• On the role of fluids in the cracks of elastic materials
  
  • Feraille Fresnet Adélaïde
  • Bui Huy Duong
  • Ehrlacher Alain
  , 2000, pp.53-64.
• Field Data vs. Theoretical Model to Quantify Drilling Efficiency and Disruption
  
  • Putot Claude
  • Perreau Philippe
  • Constantinescu Andrei
  SPE Drilling and Completion, Society of Petroleum Engineers, 2000, 15, pp.118-124. Mechanical and kinematics data at the bit have been collected during drilling operations and organized to identify optimal drilling efficiency. Transitional conditions towards abnormal behavior have been distinguished. Normal drilling is usually characterized by regular linear relationships between global control variables at the bit, which approximately correspond to an up scaling of a local Mohr Coulomb type failure mechanism of the rock. Most of our experimental data confirm this classical disposition. However, considerable departure from these relationships is noted, especially when there is BHA resonance or when there is partial balling at the bit. The field tests presented here allows us to verify classical theory and to draw up new guidelines for behavior in non- optimal or dangerous, evolving operating conditions, such as those that occur under poor cleaning conditions. The main features of a mechanical structuring model involving transition towards low efficiency conditions are presented, and it is shown how this model confirms our interpretation of field data. The model couples the drillability of rock and the general dynamics of the bit in an original and synthetic way. It makes it possible to understand and test the sensitivity of bit response to variables such as "weight on hook", torque on the drillstring and flow rate of the fluid. (10.2118/50579-MS)
  DOI : 10.2118/50579-MS
• Thermomechanical description of moving discontinuities: Application to wear
  
  • Stolz Claude
  , 2000. The propagation of moving surface inside a body is analysed within the framework of thermomechanical couplings, when the moving surface is associated with an irreversible change of mechanical properties.The moving surface is a surface of heat sources and of entropy production, intensities of which are related to particular energy release rates defined in terms of Hamiltonian gradients. As examples, we analyse the evolution of partial damage in a composite sphere and a model for study the contact wear phenomena between two bodies.
• Resource-bounded relational reasoning: induction and deduction through stochastic matching
  
  • Sebag Michèle
  • Rouveirol Céline
  Machine Learning, Springer Verlag, 2000, 38 (1-2), pp.41-62. One of the obstacles to widely using first-order logic languages is the fact that relational inference is intractable in the worst case. This paper presents an any-time relational inference algorithm: it proceeds by stochastically sampling the inference search space, after this space has been judiciously restricted using strongly-typed logic-like declarations. We present a relational learner producing programs geared to stochastic inference, named STILL, to enforce the potentialities of this framework. STILL handles examples described as definite or constrained clauses, and uses sampling-based heuristics again to achieve any-time learning. Controlling both the construction and the exploitation of logic programs yields robust relational reasoning, where deductive biases are compensated for by inductive biases, and vice versa. (10.1023/A:1007629922420)
  DOI : 10.1023/A:1007629922420
• Tribological and corrosion behaviours of graphite and titanium alloys couple during ring-on-disk tests
  
  • Serre I.
  • Celati N.
  • Pradeilles Duval R. M.
  , 2000, pp.591-596. No abstract provided
• A regularized BIE formulation for thermo-hydro-mechanical analysis of fractured rocks
  
  • Vahida B.
  • Bonnet Marc
  • Pouya A.
  , 2000. No abstract provided
• Instabilité du glissement stationnaire : application au crissement des freins
  
  • Moirot F.
  • Nguyen Q. S.
  , 2000. No abstract provided
• Investigation expérimentale et modélisation micromécanique de la déformation locale à chaud d'aciers biphasés
  
  • Pinna Christophe
  • Bornert Michel
  , 2000.
• Détection et quantification thermique de particularités d'appui et de lésions superficielles chez les marcheurs de grand fond
  
  • Parganin D.
  • Loizeau J.
  • Luong M. P.
  • Genson F.
  , 2000. No abstract provided
• Intelligent optimal design of naval structures: is it possible?
  
  • Zarka Joseph
  , 2000.
• Thermodynamical description of running discontinuities: application to wear
  
  • Stolz Claude
  , 2000.
• On global behaviour of heterogeneous media with mechanical transformation along moving surfaces
  
  • Pradeilles-Duval R. M.
  • Stolz C.
  , 2000. No abstract provided
• Damage mechanism of Ti6AL4V substrats coated by tungsten based PVD layers under single particles impact loading
  
  • Graff G.
  • Stolz C.
  • Pradeilles-Duval R. M.
  • Sainte Catherine M.C.
  • Jomeaux S.
  • Penquer F.
  , 2000. No abstract provided
• Brake squeal: a problem of flutter instability of the steady sliding solution?
  
  • Moirot Franck
  • Nguyen Quoc Son
  Archives of Mechanics, Polish Scientific Publishers Pwn, 2000, 52 (4-5), pp.645-661. Brake squeal results from friction-induced vibrations. This phenomenon is considered here and interpreted as a flutter instability of the steady sliding solution of an elastic solid in unilateral contact with friction with a moving obstacle. A mechanical analysis of the governing equations is given, in particular to obtain the steady sliding solution. The stability analysis of this solution is discussed. A numerical analysis by the finite element method is performed in order to compute the steady sliding solution and to discuss its stability for an automotive disk brake. The validation of the numerical procedure is examined in relation with some analytical results of the literature.
• On the determination of elastic coefficients from indentation experiments
  
  • Tardieu Nicolas
  • Constantinescu Andrei
  Inverse Problems, IOP Publishing, 2000, 16, pp.577-588. The main result of this paper is the extension of the adjoint state method to variational inequalities. This is done for the Signorini contact problem (Kikuchi N and Oden J T 1988 Contact Problems in Elasticity: a Study of Variational Inequalities and Finite Element Methods (Philadelphia: SIAM)) and used for the identification of elastic coefficients from an indentation test. The result is obtained by two independent approaches based on the penalized and respectively, mixed formulations of the direct problem, a Signorini contact problem. An important and astonishing result is that the obtained adjoint problem is a linear problem with Dirichlet boundary conditions. This is expected for problems described with variational equalities (Bui H D 1993 Introduction Aux Problèmes Inverses en Mécanique des Matériaux (Paris: Eyrolles) (Engl. Transl. (Boca Raton, FL: CRC Press)), Lions J L 1968 Contrôle Optimal des Systèmes Gouvernés par des Équations aux Dérivées Partielles (Dunod)), but is a new result for problems described with variational inequalities. As an application, the elastic coefficients of an isotropic body have been identified from the knowledge of a displacement-force curve measured during an indentation test. The efficiency of the method is illustrated on numerical examples for the identification of a bimaterial and a functional gradient material. (10.1088/0266-5611/16/3/303)
  DOI : 10.1088/0266-5611/16/3/303
• On the stability of rate-dependent solids with application to the uniaxial plane strain test
  
  • Nestorović Miroslav
  • Leroy Yves
  • Triantafyllidis Nicolas
  Journal of the Mechanics and Physics of Solids, Elsevier, 2000, 48, pp.1467-1491. The linear stability criterion, proposed for structural models in an earlier paper, is now extended for a general class of elastic–viscoplastic continua. The time-dependent trajectories, whose stability is under investigation, are functions of two characteristic times: the relaxation time of the viscous solid and the rate of the applied loading, with their ratio denoted by T. It is assumed that the loading conditions of the trajectory are not modified by the perturbation. The criterion predicts that a solid is initially unstable if there exists a unit norm perturbation in the velocity field whose time derivative is positive. This condition is equivalent to finding a positive eigenvalue in the self-adjoint part of the operator relating the initial first and second rate of the displacement perturbations. If the dominant eigenvalue is obtained from the non self-adjoint operator, the change in sign of its real part is a sufficient condition for instability. For solids with an associated flow rule, it is shown that the exclusion of instability in a trajectory, in the limit of vanishing T, coincides with stability of the corresponding rate-independent solid in the sense of Hill. The theory is applied to the analysis of a finitely strained rectangular block under uniaxial tension and compression, for different elastic–viscoplastic solids of the von Mises and Drucker–Prager type. (10.1016/S0022-5096(99)00094-0)
  DOI : 10.1016/S0022-5096(99)00094-0
• Évaluation de la biodisponibilité des dermocorticoïdes par thermographie infrarouge différentielle
  
  • Luong Minh Son
  • Luong Minh-Phong
  • Lok Catherine
  • Carmi Esther
  • Chaby Guillaume
  • Viseux Valérie
  Annales de Dermatologie et de Vénéréologie, Elsevier Masson, 2000, 127 (8-9), pp.701-705. Introduction</br> La technique thermographique infrarouge différentielle utilise le rayonnement infrarouge émis par la peau pour détecter, de façon non invasive et sans contact, les températures et leurs variations. Elle permet ainsi d'analyser les propriétés pharmacodynamiques (vasoconstriction) des dermocorticoïdes.</br></br> Matériels et méthodes</br> La carte thermique (thermogramme) cutanée a été enregistrée en temps réel à l'aide d'un système de détection de rayonnement infrarouge. Un test d'application unique sur un temps court, sans occlusion, et un test classique de blanchiment cutané après occlusion ont été réalisés. Un traitement par soustraction d'images a facilité l'analyse thermographique de l'effet des dermocorticoïdes des quatre classes d'activité sur peau saine.</br></br> Résultats</br> Nos résultats montrent, après une application unique sur un temps court, sans occlusion, des différences de température dans les 3 premières heures selon les corticoïdes. Le dermocorticoïde de classe II étudié en crème a provoqué un refroidissement plus intense que les autres dermocorticoïdes. L'effet de blanchiment cutané a été plus marqué pour les dermocorticoïdes de classe I et II et n'a pas été détecté pour celui de la classe IV.</br></br> Discussion</br> La possibilité de soustraire les thermogrammes les uns des autres permet d'exploiter le concept de différentielle d'images. Des différences évolutives de température après application unique, sans occlusion, de dermocorticoïdes sont mises en évidence dès les 3 premières heures. Ceci pourrait correspondre à des différences de puissance alors que le test classique de vasoconstriction n'étudie la blancheur cutanée induite qu'à partir de la 6 e heure. Pour le test de blanchiment cutané, les résultats de cette première étude sont insuffisants pour apporter une interprétation précise qualitative et quantitative. L'intérêt de la technique thermographique infrarouge différentielle est d'être une méthode quantitative, ne nécessitant pas de contact avec la peau, permettant un enregistrement continu en temps réel. Elle est plus sensible que la thermographie infrarouge classique. Elle a permis de réaliser une étude évolutive objective de l'action des dermocorticoïdes.
• Elasticity: Thermodynamic Treatment
  
  • Zaoui André
  • Stolz Claude
  , 2000, pp.2445-2449. The elastic behavior of materials is usually described by direct stress±strain relationships which use the fact that there is a one-to-one connection between the strain and stress tensors $\varepsilon$ and $\sigma$; some mechanical elastic potentials can then be defined so as to express the stress tensor as the derivative of the strain potential with respect to the strain tensor, or conversely the latter as the derivative of the complementary (stress) potential with respect to the former. Nevertheless, these potentials are restricted to specific thermodynamic conditions. This purely mechanical treatment may be generalized and improved by integrating its temperature dependence and by connecting the elastic potentials with the classical thermodynamic functions within a consistent thermodynamic framework. This leads to a more general definition of thermoelasticity (Sect. 1), which can be used for a better understanding of the properties of the elastic moduli (Sect. 2), for a natural definition of rubber elasticity (Sect. 3), and for the prediction of the effective thermal expansion coefficients of heterogeneous materials (Sect. 4). (10.1016/B0-08-043152-6/00436-8)
  DOI : 10.1016/B0-08-043152-6/00436-8
• Identification strategies for recovering material parameters from indentation experiments
  
  • Constantinescu Andrei
  • Tardieu Nicolas
  , 2000, pp.181-190. This chapter describes the progress obtained by the authors on the development of a numerical method for the identification of material parameters from indentation experiments. An indentation experiment is performed by pressing a punch on a material sample and measuring the applied force and the indentation depth. The proposed technique minimizes a least squares cost functional using gradient descent methods. In addition, the adjoint state method is extended to variational inequalities and this permits to compute the gradient of the cost functional with low numerical cost. Using this technique, a series of identifications from indentation experiments have been done and their results are discussed in this chapter. Inverse problem is of practical interest as the indentation test does not demand the creation of complicated specimens and is simple to perform. However, the applications are restricted by the difficult mechanical interpretation of the test. (10.1016/B978-008043693-7/50091-X)
  DOI : 10.1016/B978-008043693-7/50091-X
• Cavités de stockage dans le sel : évaluation de l'étanchéité
  
  • Bérest P.
  , 2000, pp.115-134. No abstract provided