Publications

2001

• Strain localization in two-phase materials and polycrystals: Quantitative experimental investigations and modeling attempts
  
  • Bornert Michel
  • Doumalin Pascal
  • Crépin Jérôme
  • Soppa Ewa
  , 2001.
• Estimations affine et au second ordre du comportement non linéaire des composites et polycristaux
  
  • Bornert Michel
  , 2001.
• Grammar-guided genetic programming and dimensional consistency: application to non-parametric identification in mechanics
  
  • Ratle Alain
  • Sebag Michèle
  Applied Soft Computing, Elsevier, 2001, 1 (1), pp.105-118. Although genetic programming has often successfully been applied to non-parametric modeling, it is frequently impaired by the huge size of the search space explored. Domain knowledge is a powerful way to trim out the size of the space, by restricting the search to a priori relevant models. A most natural domain knowledge in scientific modeling is known as dimensional analysis, stipulating that the models must be consistent with regards to the variable measurement units. In this paper, it is shown that dimensional analysis can automatically be expressed as a context free grammar. Dimensionally-aware GP is thus achieved by employing the dimensional grammar within the grammar-guided GP framework first investigated by Gruau [On using syntactic constraints with genetic programming, in: P. Angeline, K.E. Kinnear Jr. (Eds.), Advances in Genetic Programming II, MIT Press, Cambridge, MA, 1996, pp. 377–394.]. However, grammar-guided genetic programming encounters severe difficulties when it involves a complex grammar, which might explain why this approach has not been widely used so far. The drawback is blamed on the initialization step, which hardly constructs a sufficiently diversified initial population, thus hindering the success of evolution. This limitation is addressed by a new CFG compliant initialization procedure. The approach is validated on two problems related to the identification of mechanical properties of materials. (10.1016/S1568-4946(01)00009-6)
  DOI : 10.1016/S1568-4946(01)00009-6
• Non-destructive evaluation of a limit of acceptable damage for leather products
  
  • Luong Minh-Phong
  , 2001, pp.358-367.
• Thermomechanical approach of contact-wear phenomena
  
  • Stolz Claude
  , 2001, pp.183-186.
• Modelling the Electromagnetic Forces Distribution in a Three Dimensional G.M.A.W. Weld Pool
  
  • Roger F.
  • Coiffier J. C.
  • Dang Van K.
  , 2001. No abstract provided
• Avoiding the bloat with stochastic grammar-guided genetic programming
  
  • Ratle Alain
  • Sebag Michèle
  , 2002, pp.255-266. The application of Genetic Programming to the discovery of empirical laws is often impaired by the huge size of the search space, and consequently by the computer resources needed. In many cases, the extreme demand for memory and CPU is due to the massive growth of non-coding segments, the introns. The paper presents a new program evolution framework which combines distribution-based evolution in the PBIL spirit, with grammar-based genetic programming; the information is stored as a probability distribution on the grammar rules, rather than in a population. Experiments on a real-world like problem show that this approach gives a practical solution to the problem of introns growth. (10.1007/3-540-46033-0_21)
  DOI : 10.1007/3-540-46033-0_21
• Cinétique de fissuration de revêtements sur un substrat ductile : application à des dépôts de tungstène PVD déposés sur un acier
  
  • Ganne T.
  • Crépin Jérôme
  • Zaoui A.
  • Serror S.
  , 2001. No abstract provided
• Une formulation symétrique pour le couplage entre éléments finis et éléments de frontière
  
  • Mouhoubi Saïda
  • Bonnet Marc
  • Ulmet Laurent
  , 2001, 11 (2-4), pp.627-634. Cet article présente une procédure, basée sur les équations intégrales variationnelles symétriques régularisées en élasticité tridimensionnelle, permettant de construire la matrice de rigidité d'un super-élément. Celle-ci ne porte que sur les déplacements nodaux à la frontière du domaine définissant le super-élément, supposé élastique et sans force de volume. Cette technique a été implantée dans l'environnement CAST3M, y compris dans le cas où le domaine élastique contient une fissure. Trois exemples numériques tridimensionnels sont présentés: cavité sphérique pressurisée en milieu infini élastoplastique, assemblage, cylindre avec fissure. (10.3166/reef.11.277-289)
  DOI : 10.3166/reef.11.277-289
• Application du contrôle optimal à l'identification d'un chargement thermique
  
  • Delattre Benoît
  • Ivaldi Damien
  • Stolz Claude
  , 2001, 11 (2-4), pp.165-172. La détermination du champ de température sur certaines pièces d'un moteur est obtenue par la résolution d'un problème inverse. Une alternative aux méthodes expérimentales coûteuses utilisées aujourd'hui est la méthode du contrôle optimal qui permet d'estimer le champ de température à partir de quantités mesurées sur pièce. Différents tests préfigurent des possibilités de prédiction et de fiabilité de la méthode. (10.3166/reef.11.393-404)
  DOI : 10.3166/reef.11.393-404
• Solid-fluid phase transformation within grain boundaries during compaction by pressure solution
  
  • Ghoussoub Joumana
  • Leroy Yves
  Journal of the Mechanics and Physics of Solids, Elsevier, 2001, 49 (10), pp.2385-2430. The overall compaction of porous rocks due to intergranular pressure solution (IPS) results from the dissolution of minerals within contact regions and the diffusive transport through the grain boundary of the dissolved species towards the fluid-filled pore space. The grain boundary structure can be imagined to be composed of dry contact zones, thin fluid films and fluid-filled cavities. The connectiveness and tortuosity of this structure determine the effective diffusivity of grain contacts and thus the potential of porous rock to compact by the action of IPS. The evolution in time of the grain-boundary structure, and thus of the effective diffusivity, is discussed here with the help of two 2D initial- and boundary-value problems which are solved by analytical and numerical means. The evolution of the solid–fluid interfaces within the grain boundary is governed by a phase transformation between the non-hydrostatically stressed elastic solid and the trapped fluid assumed in mechanical equilibrium. The characteristic time is provided by a linear kinetic law. The evolution of the structure away from a state of thermodynamic equilibrium during a loading normal to the grain boundary is found to occur in two steps. The first one consists of a diffuse morphology evolution in time and results in an enhancement of any initial stress concentration. The second step is characterized by a rapid and localized dissolution in the region of stress concentration. The latency period prior to localization is governed by the magnitude of the non-hydrostatic remote stress as well as the microstructural geometric factor responsible for the initial stress concentration at the solid–fluid interface. The localized dissolution is shown to provide a mechanism for the fluid to penetrate a previously dry contact region by marginal dissolution and thus to create a fluid film. However, the newly formed thin fluid layer is found to be unstable pointing to a possible repeated reorganization or dynamic evolution of the grain boundary internal structure during the action of IPS. (10.1016/S0022-5096(01)00012-6)
  DOI : 10.1016/S0022-5096(01)00012-6
• Affaissement en surface lors du creusement d'un souterrain
  
  • Bérest Pierre
  • Ghoreychi Mehdi
  • Habib Pierre
  Revue française de Géotechnique, edp sciences, 2001, 92, pp.41-47. L’affaissement à long terme de la surface du sol au-dessus d’un tunnel est comparé à l’affaissement instantané au moment du creusement dans le cadre de l’élasticité linéaire. Les résultats numériques montrent, sur des exemples vraisemblables, que si des déplacements importants sont décelés en surface, il s’agit très probablement de déformations irréversibles. (10.1051/geotech/2000092041)
  DOI : 10.1051/geotech/2000092041
• sur les mécanismes de la plasticité et de l'endommagement
  
  • Berveiller M.
  • Bretheau T.
  • Fougères R.
  • Gautier E.
  • Maire E.
  , 2001, pp.203-249.
• Inductive Logic Programming
  
  • Rouveirol Céline
  • Sebag Michèle
  , 2001, 2157. (10.1007/3-540-44797-0)
  DOI : 10.1007/3-540-44797-0
• Etude thermodynamique de l'évolution sous chargement dynamique de structures délaminées
  
  • Pradeilles-Duval Rachel Marie
  Comptes rendus de l’Académie des sciences. Série IIb, Mécanique, Elsevier, 2001, 329, pp.535-540. On considère un assemblage de plaques modélisant une structure stratifiée se délaminant. La propagation du délaminage est caractérisée par la transformation d'une plaque en deux autres. On examine dans le cadre du formalisme hamiltonien l'influence d'un chargement dynamique sur une telle structure, d'un point de vue thermodynamique. L'étude du taux de restitution associé à la propagation de la fissure, considérée comme une source de chaleur localisée sur le front de délaminage, est discutée. (10.1016/S1620-7742(01)01364-2)
  DOI : 10.1016/S1620-7742(01)01364-2
• X-ray computed tomography of sugar crystals flow in silo
  
  • Luong M. P.
  , 2001, pp.403-407. No abstract provided
• Exploiting complete or partial geometrical symmetry in Symmetric Galerkin BEM
  
  • Bonnet Marc
  , 2001, pp.527-534. No abstract provided
• Creep of argillites under small mechanical loading
  
  • Bérest Pierre
  • Charpentier Jean-Pierre
  • Valès Frédéric
  , 2001. Study of rocks under small (typically s = 0.1 MPa) mechanical loading is of great importance both for a better understanding of geological deformation features and for the analysis of rock mass behavior at large distance from underground openings. A very small amount of experimental data is available. Very long-term tests are required, as the creep rates induced by such small mechanical loading are exceedingly small (10 ­13 to 10-12s-1). Accurate displacement measurements and a thorough control of both hygrometry and temperature must be used. We used high resolution displacements sensors, whose resolution is 10-9m, designed for purpose by P.A.Blum from IPG Paris. The creep test system were set in a 20-m deep gallery where hygrometry is close to 100%PHs suburbs ; and in a 200-m deep salt mine where hygrometry is 54+/-2% RH . In both sites daily temperature fluctuations are smaller than a few hundredth of a Celsius degree, allowing for quite constant ambient conditions during several month long tests, the observed displacement-versus-time curves can be corrected from the thermoelastic effects. Creep of salt samples was measured in the 200-m deep mine ; transient creep, steady-state creep and the effcts of stress drop were observed during a 18-month long test. The measured steady-state creep rates (10-12s-1) are much faster than the values extrapolated from standard tests performed under larger mechanical loading. Argillite creep was measured in the 20-m deep gallery. High hygrometry conditions result in relatively fast clay swelling. In this context, argillite creep rate, which is slower than swelling rate by one order of magnitude, is difficult to identify
• Storage of tritiated water in salt caverns
  
  • Bérest Pierre
  • Brouard Benoit
  , 2001.
• A new approach for Hardening Rate Measurements in HCP Materials and Applications in Mechanical Modelling
  
  • Philippe Marie-Jeanne
  • Crépin Jérôme
  • Lecomte J.S.
  , 2001.
• Dynamique des systèmes de solides rigides avec liaisons unilatérales ou frottement
  
  • Ballard Patrick
  , 2001.
• Some aspects of dynamic testing with wave-guides
  
  • Gary G.
  , 2001.
• Intelligent design of woven composites
  
  • Zarka Joseph
  • Doux Thierry
  , 2001. (10.1016/S0167-6636(02)00259-4)
  DOI : 10.1016/S0167-6636(02)00259-4
• Étude modale d'une clarinette
  
  • Facchinetti Matteo Luca
  • Constantinescu Andrei
  • Boutillon Xavier
  , 2001. Ce travail est une contribution à la compréhension de la dynamique d’une clarinette en conditions de jeu. On propose une modélisation complète de l’instrument, en éléments finis fluides et solides, dont on analyse les modes propres réels : les résultats sont comparés avec des mesures expérimentales, par interférométrie holographique, en validant ainsi le modèle numérique.
• Boundary element based formulations for crack shape sensitivity analysis
  
  • Bonnet Marc
  Engineering Analysis with Boundary Elements, Elsevier, 2001, 25, pp.347-362. The present paper addresses several BIE-based or BIE-oriented formulations for sensitivity analysis of integral functionals with respect to the geometrical shape of a crack. Functionals defined in terms of integrals over the external boundary of a cracked body and involving the solution of a frequency-domain boundary-value elastodynamic problem are considered, but the ideas presented in this paper are applicable, with the appropriate modifications, to other kinds of linear field equations as well. Both direct differentiation and adjoint problem techniques are addressed, with recourse to either collocation or symmetric Galerkin BIE formulations. After a review of some basic concepts about shape sensitivity and material differentiation, the derivative integral equations for the elastodynamic crack problem are discussed in connection with both collocation and symmetric Galerkin BIE formulations. Building upon these results, the direct differentiation and the adjoint solution approaches are then developed. In particular, the adjoint solution approach is presented in three different forms compatible with boundary element method (BEM) analysis of crack problems, based on the discretized collocation BEM equations, the symmetric Galerkin BEM equations and the direct and adjoint stress intensity factors, respectively. The paper closes with a few comments. (10.1016/S0955-7997(01)00025-X)
  DOI : 10.1016/S0955-7997(01)00025-X