Publications

2001

• 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
• 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
• 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.
• Increasing the maximum strain measured with the elastic and viscoelastic Hopkinson bars
  
  • Othman Ramzi
  • Bussac Marie-Noëlle
  • Collet Pierre
  • Gary Gérard
  , 2001.
• Tomographie aux rayons X de l'écoulement du sucre en poudre ensilé
  
  • Luong M. P.
  , 2001. No abstract provided
• Moving discontinuities: applications to fracture and wear
  
  • Stolz Claude
  , 2001.
• Caractérisation de l'écrouissage dans des monocristaux de Zirconium
  
  • Lecomte J. S.
  • Crépin Jérôme
  • Philippe Marie-Jeanne
  , 2001.
• 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.
• Evolution de la pression dans une caverne remplie de fluide
  
  • Bérest P.
  • Brouard B.
  • Bergues J.
  • Durup G.
  , 2001, pp.96. No abstract provided
• Un exemple d'onde stick-slip
  
  • Moirot F.
  • Nguyen Q. S.
  , 2001, pp.229-236. 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
• Exploiting partial or complete geometrical symmetry in boundary integral equation formulations of elastodynamic problems
  
  • Bonnet Marc
  , 2001, pp.253-270. Procedures based on group representation theory, allowing the exploitation of geometrical symmetry in symmetric Galerkin BEM formulations of 3D elastodynamic problems, are developed. They are applicable for both commutative and noncommutative finite symmetry groups and to partial geometrical symmetry, where the boundary has two disconnected components, one of which is symmetric. (10.1007/978-3-642-56288-4_18)
  DOI : 10.1007/978-3-642-56288-4_18
• 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
• Branch crack development from the flank of a fatigue crack propagating in mode II
  
  • Doquet Véronique
  • Frelat Joël
  Fatigue and Fracture of Engineering Materials and Structures, Wiley-Blackwell, 2001, 24 (3), pp.207-214. The propagation of fatigue cracks in mode II often leads to the development of a branch starting from a crack flank, some distance behind the tip and not to the expected bifurcation at the crack tip. This type of branch is suggested to initiate by decohesion along a secondary slip plane and to grow in mode I due to the tensile component of the mode II stress field. Finite element calculations are performed to evaluate the stress intensity factors for the main crack and the branch as a function of the position of the latter. It is shown that the branch has a substantial shielding effect on the main crack and generates contact forces along its flanks. The simultaneous and competitive growth of the main crack and the branch in fatigue is simulated step by step using kinetic data for mode II and mode I obtained for a maraging steel. (10.1046/j.1460-2695.2001.00384.x)
  DOI : 10.1046/j.1460-2695.2001.00384.x
• Changement d'échelle: motivation et méthodologie
  
  • Zaoui A.
  , 2001, pp.19-39.
• Approche expérimentale de l'homogénisation
  
  • Bretheau T.
  , 2001, pp.147-169.
• Approches par les potentiels
  
  • Bornert Michel
  • Suquet P.
  , 2001, pp.45-90.
• Plasticité: approches en champ moyen
  
  • Zaoui A.
  , 2001, pp.17-44.
• Grain-size-sensitive flow and shear-stress enhancement at the brittle-ductile transition of the continental crust
  
  • Gueydan Frédéric
  • Leroy Yves
  • Jolivet Laurent
  International Journal of Earth Sciences, Springer Verlag, 2001, 90 (1), pp.181-196. Localized shear zones along low-angle normal faults have been identified in regions of extension at the brittle–ductile transition of the continental crust. The possibility of the strain localizing at a depth of 10 km is interpreted here as a consequence of an increase in the equivalent shear stress applied to the flow of the lower crust. This enhancement of the flow stress is seen as a prerequisite for the triggering of brittle deformation mechanisms leading to strain localization. The lower crust rheology used to examine this stress increase is strain-rate, temperature and grain-size dependent, due to the coupling of dislocation and diffusion creep. The model structure proposed consists of a top layer, the upper crust, gliding rigidly above a bottom layer, the lower crust, which deforms in simple shear. During a short time interval (1400 years), the equivalent shear stress is found to increase by a factor of up to 3 (67 MPa for anorthite and 17 MPa for quartz). For anorthite, this stress could explain the activation of a Mohr-Coulomb failure with a friction coefficient of 0.2, which is reasonable at the depth of 10 km. Dislocation creep is activated during a rapid change in the prescribed velocity, whereas diffusion creep dominates if the velocity is held constant, highlighting the importance of grain-size sensitivity for lower crustal rheology. (10.1007/s005310000160)
  DOI : 10.1007/s005310000160
• Utilisation de symétries géométriques totales ou partielles dans la méthode des éléments de frontière
  
  • Bonnet Marc
  , 2001, pp.659-666. No abstract provided
• Observation infrarouge de l'endommagement des cordes de tennis
  
  • Luong M. P.
  , 2001. No abstract provided
• On a predictive macroscopic contact-sliding wear model based on micromechanical considerations
  
  • Dragon-Louiset Marta
  International Journal of Solids and Structures, Elsevier, 2001, 38, pp.1625-1639. A model for the mild wear of two contacting solids and an analytical example are proposed in this article. The model includes the presence of an interface made of damaged materials, fluid and wear debris. It consists in a wear criterion, an interface law and complementary relations deduced from the mass conservation. A thermodynamical analysis provides energy-release rates associated with the evolution of the surfaces in contact and the mass fluxes due to wear. They are used as characteristic quantities in the formulation of the wear criterion and wear velocities. Given that the physics of the interface modify the global contact conditions, micromechanical considerations are developed and result in an interface law, modeling its evolution with an internal parameter: the volume fraction of wear debris. The relation between this parameter and wear velocities is obtained with the mass conservation equation, which completes the model and allows to apply it in a numerical simulation. As an example, a problem of a rigid punch sliding on an elastic worn-out half-plane is treated by means of integral equations, accounting on the presence of an interface according to the previous modeling. Stresses and strains are obtained analytically, as asymptotic expansion fields. (10.1016/S0020-7683(00)00065-2)
  DOI : 10.1016/S0020-7683(00)00065-2
• Modélisation micromécanique de la phase lamellaire des alliages TiAl
  
  • Gélébart Lionel
  • Bretheau Thierry
  • Crépin Jérôme
  • Bornert Michel
  , 2001.