Publications

2000

• Plasticity of zirconium at intermediate temperatures: effect of a small quantity of sulfur
  
  • Ferrer F.
  • Bretheau Th.
  • Crépin Jérôme
  • Barbu A.
  , 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
• Quelques exemples de vibrations et d'instabilité induites par le frottement
  
  • Nguyen Q. S.
  , 2000. No abstract provided
• A critical study of SHPB test on the materials involved in crash problems
  
  • Zhao H.
  • Gary G.
  , 2000. No abstract provided
• 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.
• Brake squeal: a problem of flutter instability of the steady sliding solution ?
  
  • Moirot Franck
  • Son Nguyen Quoc
  Archives of Mechanics, 2000, 4-5, pp.645-662. Brake squeal results from friction-induced vibrations. This phenomena 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.
• 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
• Dynamic testing of fibre polymer matrix composite plates under in-plane compression
  
  • Gary Gérard
  • Zhao H.
  Composites Part A: Applied Science and Manufacturing, Elsevier, 2000, 31, pp.835-840. Experimental investigations of the failure strength of fibre reinforced polymer matrix composite plates under compressive impact loading is presented in this paper. A split Hopkinson pressure bar (SHPB) is used to measure these properties. The specimen being a plate, its cross-sectional area is small compared with the area of the bars and the failure strength is weak. One has to then use low impedance bars made of a viscoelastic material. Subsequent experimental problems, such as dispersion corrections in viscoelastic bars, are analysed. One also has to use a special anti-buckling device to prevent the overall buckling of the specimen. It is shown that the presented SHPB system provides a precise measurement of forces and displacements at both ends of the specimen. A special attention is then given to the analysis of the test, especially in situations where a non-homogeneous state of stress in the specimen in observed. (10.1016/S1359-835X(00)00026-9)
  DOI : 10.1016/S1359-835X(00)00026-9
• A plasticity model for discontinua
  
  • Leroy Yves
  • Sassi William
  , 2000, pp.77-107. This article is concerned with the development and application of a simple continuum theory for rocks that may contain both randomly as well as preferentially oriented plane discontinuity surfaces. The theory stipulates that displacement discontinuities are independently activated on these surfaces as soon as an appropriate yield criterion is fulfilled; these displacement jumps account for the irreversible, ‘plastic’ part of the bulk deformation. In stress space, the critical conditions for the activation of discontinuous slip or opening displacements define an overall yield envelope that could be initially anisotropic, reflecting for example a weakness of certain orientations due to pre-existing joint sets. For the yield conditions studied in this paper, essentially a Coulomb-type friction law and a simple fracture opening condition, the inferred stress-strain response under typical triaxial loading conditions reveals the sensitivity of the two discontinuous deformation modes to the confining pressure. The incipient growth of a geological fold in such a material is modelled as a problem of plate bending. The slip- and opening-modes of deformation are found to be activated typically in the fold intrados and extrados, respectively. Under certain conditions, both modes will be activated simultaneously at the same locality and contribute to the total deformation. Field observations on a well exposed sandstone anticline are reported here, which support this conclusion. The present plasticity model for discontinua can clearly be explored in more detail for realistic distributions of faults and joints taken from field observations. It could also be improved in various ways in its description of the underlying deformation mechanisms. Apart from its interest as a mechanical constitutive model, it can also serve as a point of departure for studies of stress-sensitive, anisotropic permeability distributions in fractured formations. (10.1007/978-3-642-59617-9_5)
  DOI : 10.1007/978-3-642-59617-9_5
• Approche multi-échelle en fatigue polycyclique anisotherme
  
  • Maitournam Habibou
  • Nguyen-Tajan Thi Mac-Lan
  Comptes rendus de l’Académie des sciences. Série IIb, Mécanique, Elsevier, 2000, 328 (5), pp.373-379. Une extension de l'approche macro-méso développée par Dang Van en fatigue isotherme à grand nombre de cycles est proposée dans le cas de structures subissant des chargements cycliques anisothermes et dont les limites de fatigue dépendent de la température. Elle est essentiellement fondée sur l'hypothèse d'adaptation aux échelles macroscopique et mésoscopique. L'utilisation d'une condition locale d'adaptation écrite dans le cas anisotherme conduit à une nouvelle formulation des critères de fatigue. (10.1016/S1620-7742(00)00049-0)
  DOI : 10.1016/S1620-7742(00)00049-0
• The dynamics of discrete mechanical systems with perfect unilateral constraints
  
  • Ballard Patrick
  Archive for Rational Mechanics and Analysis, Springer Verlag, 2000, 154 (3), pp.199-274. The dynamics of discrete mechanical systems with perfect unilateral constraints is formulated in a very general setting. The well-posedness of the resulting evolution problem is studied. It is proved that existence and uniqueness of a maximal solution is ensured provided strong assumptions are made on the regularity of the data: they are supposed to be analytic. Simple examples show that this regularity assumption may not be relaxed. Sufficient conditions to ensure that the maximal solution is defined for all time are supplied. The continuous dependence of the solution on initial conditions is also studied and the numerical computation of the solution is discussed. (10.1007/s002050000105)
  DOI : 10.1007/s002050000105
• La programmation logique inductive à la lumière de la transition de phase
  
  • Giordana Attilio
  • Saitta Lorenza
  • Sebag Michèle
  • Botta Marco
  , 2000, pp.157-172. En logique du premier ordre, le test de couverture correspond à un problème de satisfaction de contraintes. Or, dans le domaine de la satisfaction de contraintes, les problèmes les plus difficiles à résoudre en moyenne se concentrent dans une étroite région, appelée transition de phase, qui marque la transition entre les problèmes presque surement satisfiables, et les problèmes presque surement insatisfiables. Pour étudier la complexité et la faisabilité de la Programmation Logique Inductive (PLI), nous avons généré quelques centaines de problèmes d’apprentissage, situés dans et hors de la transition de phase; ces problèmes ont été soumis à FOIL, SMART+ et G-Net. Ces expérimentations systématiques établissent deux résultats. Tout d’abord, la transition de phase constitue un attracteur pour l’apprentissage, dans le sens où toutes les hypothèses produites appartiennent à cette région. En second lieu, une "zone aveugle de l’apprentissage" apparaît: pour tout problème situé dans cette zone, les systèmes de PLI considérés échouent tous à apprendre quelque hypothèse pertinente que ce soit. Ces résultats sont interprétés, et la discussion conduit à remettre en cause les biais usuels de la PLI.
• On discontinuous stresses at the interface of a bimaterial thermo-elasto-plastic body
  
  • Bui Huy Duong
  • Taheri Said
  • Dang Van Ky
  Advances in Natural Sciences, 2000, 1, pp.79-84.
• Plan/plan sliding contact modelling by the boundary element method
  
  • Serre Ingrid
  • Bonnet Marc
  • Pradeilles-Duval Rachel Marie
  , 2000.
• Hétérogénéité des contraintes au sein d'un matériau lamellaire. Application à un alliage intermétallique TiAl
  
  • Gélébart Lionel
  • Crépin Jérôme
  • Bretheau Thierry
  • Bornert Michel
  , 2000.
• An affine formulation for the prediction of the effective properties of nonlinear composites and polycrystals
  
  • Masson Renaud
  • Bornert Michel
  • Suquet Pierre
  • Zaoui André
  , 2000. Variational approaches for nonlinear elasticity show that Hill's incremental formulation for the prediction of the overall behaviour of heterogeneous materials yields estimates which are too stiff and may even violate rigorous bounds. This paper aims at proposing an alternative `affine' formulation, based on a linear thermoelastic comparison medium, which could yield softer estimates. It is first described for nonlinear elasticity and specified by making use of Hashin±Shtrikman estimates for the linear comparison composite; the associated affine self-consistent predictions are satisfactorily compared with incremental and tangent ones for power-law creeping polycrystals. Comparison is then made with the second-order procedure and some limitations of the affine method are pointed out; explicit comparisons between different procedures are performed for isotropic, two-phase materials. Finally, the affine formulation is extended to history-dependent behaviours; application to the self-consistent modelling of the elastoplastic behaviour of polycrystals shows that it others an improved alternative to Hill's incremental formulation. (10.1016/S0022-5096(99)00071-X)
  DOI : 10.1016/S0022-5096(99)00071-X
• Dynamic testing at high rates of strain
  
  • Gary G.
  , 2000.
• Self-consistent estimates for nonlinear viscoelastic polycrystals: a simplified resolution of the affine formulation adapted to monotonic loading paths
  
  • Brenner Rénald
  • Castelnau Olivier
  • Masson Renaud
  • Bacroix Brigitte
  • Zaoui André
  , 2000, 177-180, pp.153-158. A simplified resolution of the self-consistent model for non-linear viscoelastic polycrystals is presented. The formulation is based on an affine linearization of the constitutive relations as recently proposed by Masson and Zaoui [4], which adapts Hill's conception of self-consistent modelling to nonlinear viscoelastic behaviours. The approximation of the inverse Laplace-Carson transform introduced here, which is believed to be well adapted to monotonic loading paths, makes the resolution of the whole self-consistent problem possible in the direct time space. This results in a largely simplified numerical algorithm. Comparisons with the predictions of a model treating accurately the inverse Laplace-Carson transform are presented, and very good results are obtained for creep of FCC and HCP polycrystals. (10.4028/www.scientific.net/KEM.177-180.153)
  DOI : 10.4028/www.scientific.net/KEM.177-180.153
• An energetic approach in thermomechanical fatigue for silicium molybden cast iron
  
  • Charkaluk E.
  • Constantinescu Andreï
  Materials at High Temperatures, Taylor and Francis, 2000, 17 (3), pp.373-380. The purpose of this paper is to define a low cycle fatigue criterion in order to predict the failure of engineering structures. The major problem in defining a predictive fatigue criterion is that it should be applicable for structures submitted to complex multiaxial thermo-mechanical loadings but should be identifiable from simple experiments on specimens. After a short critical review of the principal criteria used in low cycle fatigue it will be shown that the dissipated energy per cycle permits a correlation of isothermal and anisothermal results obtained on silicon molybdenum cast iron in the case of specimens and also on structures. (10.1179/mht.2000.17.3.001)
  DOI : 10.1179/mht.2000.17.3.001
• 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
• Instabilité du glissement stationnaire : application au crissement des freins
  
  • Moirot F.
  • Nguyen Q. S.
  , 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.
• 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
• Thermodynamical description of running discontinuities: application to wear
  
  • Stolz Claude
  , 2000.