Publications

2001

• Stability of a quasi-static evolution of a visco-elastic, visco-plastic or elastic-plastic solid
  
  • Abed-Meraim Farid
  • Nguyen Quoc Son
  , 2001, pp.1-14. The problem of stability of a quasi-static evolution of a solid is discussed in the framework of standard plasticity and visco-plasticity. General results concerning the criterion of second variation of energy are presented. Two different approaches are considered to discuss this problem for visco-elastic, visco-plastic or elastic-plastic solids. The first approach is based upon the linearization method and gives the asymptotic stability of the evolution of a visco-elastic solid when the associated dissipation potential is quadratic and positive-definite. The second approach introduces a direct analysis of the evolution in a nonsmooth but convex framework of plasticity and visco-plasticity. (10.1007/978-1-4613-0275-9_1)
  DOI : 10.1007/978-1-4613-0275-9_1
• A Salt-cavern abandonment test
  
  • Bérest Pierre
  • Bergues Jean
  • Brouard Benoît
  • Durup Gerard
  • Guerber Benoît
  International Journal of Rock Mechanics and Mining Sciences, Pergamon and Elsevier, 2001, 38 (3), pp.357-368. Thousands of caverns have been leached out from deep salt formations. They are used for saturated brine production and/or hydrocarbons storage. They will be abandoned some day: the access well will be plugged with cement, isolating a large bubble of saturated brine. The later evolution of such a bubble raises serious concerns for environmental protection; salt creep and brine thermal expansion can lead to brine pressure build-up and rock-mass fracture, then brine seepage can lead to pollution of overlying water-bearing strata. Taking into account salt formation permeability leads to less pessimistic scenarios. An 18-month test has been performed on a deep brine-filled cavern. The objective was to measure the brine equilibrium pressure reached when the cavern is closed. Such an equilibrium is reached when salt mass creep, which leads to cavern shrinkage, balances brine permeation through the cavern wall. This objective was met by imposing different pressure levels and observing whether the pressure increased (or decreased) with respect to time. Data misinterpretation (i.e., a well leak instead of a cavern-proper leak) was precluded by a special monitoring system. The observed equilibrium pressure was significantly smaller than geostatic pressure, alleviating any fracture risk for a sealed and abandoned cavern in this salt formation. (10.1016/S1365-1609(01)00004-1)
  DOI : 10.1016/S1365-1609(01)00004-1
• Life-time prediction of aluminum automotive components under thermo-mechanical cyclic loadings
  
  • Verger Laetitia
  • Charkaluk Eric
  • Constantinescu Andrei
  , 2001.
• Identification of constitutive parameters in engineering problems
  
  • Constantinescu Andrei
  • Lecampion Brice
  • Verger Laetitia
  • Tardieu Nicolas
  , 2001.
• Un outil de la mécanique des matériaux : la micro-extensométrie
  
  • Bretheau Thierry
  • Crépin Jérôme
  • Doumalin Pascal
  • Bornert Michel
  , 2001.
• Action d'une conduite circulaire sur un sol cohérent
  
  • Salençon Jean
  , 2001, 2001-08-31, pp.1311-1314. On s'intéresse à la détermination théorique de la capacité portante d'un sol homogène, isotrope, purement cohérent sur lequel repose une conduite circulaire. Les deux conditions extrêmes de contact à l'interface entre la conduite et le sol (interface lisse sans résistance à la traction et interface totalement adhérente) sont envisagées ce qui permet d'encadrer la solution du problème réel. On a appliqué les méthodes d'approche par l'intérieur statique et d'approche par l'extérieur cinématique de la théorie du calcul à la rupture pour une analyse paramétrique en fonction de la profondeur d'enfoncement de la conduite. Les évaluations par défaut et par excès ainsi obtenues montrent que l'effet de la gravité est purement additif, égal à la simple «poussée d'Archimède» exercée par le sol et améliorent, dans le cas de l'interface lisse, les résultats antérieurs de Mur1l: Wagner & Randolph.
• On the behaviour characterisation of polymeric foams over a large range of strain rates
  
  • Zhao Han
  • Gary Gérard
  , 2001, pp.23-28. The testing and modelling of the mechanical behaviour of some polymeric foams involved in the automotive industry are presented. A variety of current experimental arrangements over a large range of strain rates have been reviewed. Recent improvements of a particularly useful technique for impact loading–the split Hopkinson bar–are presented. A phenomenological model is developed to describe experimental data. Difficulties for 3-dimensional testing and modelling are also discussed.
• Study of the creep behavior of a possible host clayey rock
  
  • Gasc-Barbier M.
  • Chanchole S.
  • Lecampion B.
  • Bérest P.
  • Hoteit N.
  , 2001. No abstract provided
• Fatigue Analysis during One-parametered Loadings
  
  • Zarka Joseph
  • Karaouni Habib
  , 2001.
• Effet de la fréquence et de l'environnement sur la propagation des fissures de fatigue en mode II dans un acier maraging
  
  • Doquet V.
  , 2001. No abstract provided
• Techniques of Infrared Thermography
  
  • Luong M. P.
  , 2001, pp.342-357.
• Etude de systèmes avec surfaces de discontinuités mobiles sous chargement thermomécanique
  
  • Peigney Michaël
  • Stolz C.
  , 2001. No abstract provided
• Application du principe du maximum de vraisemblance à la séparation des ondes dans les barres
  
  • Othman Ramzi
  • Bussac Marie-Noëlle
  • Collet Pierre
  • Gary Gérard
  , 2001.
• θ-Subsumption in a Constraint Satisfaction Perspective
  
  • Maloberti Jérôme
  • Sebag Michèle
  , 2001, 2157, pp.164-178. The covering test intensively used in Inductive Logic Programming, i.e. θ-subsumption, is formally equivalent to a Constraint Satisfaction problem (CSP). This paper presents a general reformulation of θ-subsumption into a binary CSP, and a new θ-subsumption algorithm, termed Django, which combines some main trend CSP heuristics and other heuristics specifically designed for θ-subsumption. Django is evaluated after the CSP standards, shifting from a worst-case complexity perspective to a statistical framework, centered on the notion of Phase Transition (PT). In the PT region lie the hardest on average CSP instances; and this region has been shown of utmost relevance to ILP [4]. Experiments on artificial θ-subsumption problems designed to illustrate the phase transition phenomenon, show that Django is faster by several orders of magnitude than previous θ-subsumption algorithms, within and outside the PT region. (10.1007/3-540-44797-0_14)
  DOI : 10.1007/3-540-44797-0_14
• Experimental and numerical characterisation of in plane deformation in two-phase materials
  
  • Soppa Ewa Anna
  • Doumalin Pascal
  • Binkele Peter
  • Wiesendanger Tobias
  • Bornert Michel
  • Schmauder Siegfried
  Computational Materials Science, Elsevier, 2001, 21 (3), pp.261-275. The aim of the present work consists in the comparison of in-plane strain fields with out-of-plane displacements in micro-areas of an Ag/Ni-composite after a macroscopic compressive deformation of 8.6%. The in-plane deformations in an Ag/Ni-composite have been analysed experimentally with a high resolution object grating technique and numerically using the finite element method. The out-of-plane displacements were measured with an atomic force microscope (AFM). The development of local strain fields in micro-areas at the surface of an Ag/Ni-composite was simulated numerically using the FE-method in plane strain condition. A real cut-out of the microstructure served as input for the calculation. The out-of-plane displacements determined by AFM measurements were used further to correct the in-plane values of strains evaluated by the object grating technique. The roughness on the surface of the sample was characterised by fractal dimensions and compared with the in-plane strains in the same micro-region. (10.1016/S0927-0256(01)00170-7)
  DOI : 10.1016/S0927-0256(01)00170-7
• Evolution de la pression dans une caverne remplie de fluide
  
  • Bérest P.
  • Brouard B.
  • Bergues J.
  • Durup G.
  , 2001, pp.96. No abstract provided
• Back analysis on mechanical behaviour of joints, using a new method based on virtual work principle
  
  • Deng D.
  • Nguyen-Minh D.
  , 2001, pp.915-919. No abstract provided
• Caractérisation de l'écrouissage dans des monocristaux de Zirconium
  
  • Lecomte J. S.
  • Crépin Jérôme
  • Philippe Marie-Jeanne
  , 2001.
• Tomographie aux rayons X de l'écoulement du sucre en poudre ensilé
  
  • Luong M. P.
  , 2001. No abstract provided
• Modification du critère de Gurson par une approche micromécanique
  
  • Bilger Nicolas
  • Auslender François
  • Bornert Michel
  • Masson Renaud
  • Zaoui André
  , 2001.
• Matériaux du nucléaire
  
  • Zaoui A.
  , 2001.
• Some recent advances in symmetric Galerkin boundary element methods and their coupling with finite elements
  
  • Bonnet Marc
  , 2001.
• Modal analysis of a complete clarinet
  
  • Facchinetti Matteo Luca
  • Boutillon Xavier
  • Constantinescu Andrei
  , 2001. A modal computation of a complete clarinet is presented by the association of finite-element models of the reed and of part of the pipe, and a lumped-element model of the rest of the pipe. This is a continuation of an initial work by Pinard and Laine (unpublished reports of the Ecole Polytechnique) on isolated reeds. The eigenmodes of the complete system are computed and the results lead to a discussion of the following points: flexion and torsion modes of the reed, their coupling to the acoustical field, plane wave hypothesis, equivalent volume approximation in the mouthpiece, and alignment of resonance peaks.
• On shakedown theorems in hardening plasticity
  
  • Nguyen Quoc Son
  • Pham Duc Chinh
  Comptes rendus de l’Académie des sciences. Série IIb, Mécanique, Elsevier, 2001, 329, pp.307-314. The model of generalized standard materials gives a convenient framework to extend Koiter's shakedown theorems into hardening plasticity. The extension of the static shakedown theorem (Melan–Koiter's theorem), proposed previously in [5], is considered here. It leads to the definition of safety coefficients in hardening plasticity by duality. Static and kinematic approaches are discussed for the models of isotropic hardening, of linear kinematic hardening (Ziegler–Prager's model) and of limited kinematic hardening. This discussion also leads to an extension of Koiter's kinematic shakedown theorem and to a second kinematic coefficient. (10.1016/S1620-7742(01)01321-6)
  DOI : 10.1016/S1620-7742(01)01321-6
• Moving discontinuities: applications to fracture and wear
  
  • Stolz Claude
  , 2001.