Publications

2000

• Cavités de stockage dans le sel : évaluation de l'étanchéité
  
  • Bérest P.
  , 2000, pp.115-134. No abstract provided
• Experimental investigation and micromechanical modeling of the hot deformation of duplex stainless steels
  
  • Pinna C.
  • Bornert Michel
  • Beynon J. H.
  • Sellars C. M.
  , 2000. No abstract provided
• Caractérisation morphologique 3D des matériaux de structure hétérogènes par microtomographie X et traitement d'image pour la prévision du comportement mécanique
  
  • Bornert Michel
  • Jeulin Dominique
  • Maire E.
  • Moulinec H.
  • Chaix J.-M.
  , 2000. No abstract provided
• Etude expérimentale du comportement à la fissuration des dépôts de tungstène PVD en fonction de leurs épaisseurs
  
  • Ganne T.
  • Crépin Jérôme
  • Zaoui A.
  • Pradeilles-Duval R. M.
  , 2000. No abstract provided
• Finite element simulation of the deformation of b.c.c. aggregates using a crystal plasticity model - local orientation effects
  
  • Arizmendi D.
  • Raphanel J. L.
  , 2000, pp.27-32. No abstract provided
• Full or partial geometrical symmetry in symmetric Galerkin BEM
  
  • Bonnet Marc
  , 2000, pp.57-62. No abstract provided
• Folding and localized faulting in a frictional, cohesive overburden resting over a viscous substratum
  
  • Leroy Y.M.
  • Triantafyllidis N.
  , 2000, pp.109-140.
• Principles for the `intelligent' optimal design of materials and structures
  
  • Zarka Joseph
  , 2000.
• Crack propagation from a pre-existing flaw at a notch root. II: Detailed form of the stress intensity factors at the initial crack tip and conclusion
  
  • Leblond Jean-Baptiste
  • Mouro Pierre
  International Journal of Fracture, Springer Verlag, 2000, 104, pp.225-239. This paper pursues the study of crack kinking from a pre-existing crack emanating from some notch root. It was shown in Part I that the stress intensity factors at the tip of the small initial crack are given by universal (that is, applicable in all situations, whatever the geometry of the body and the loading) formulae; they depend only on the `stress intensity factor of the notch' (the multiplicative coefficient of the singular stress field near the apex of the notch in the absence of the crack), the length of the crack, the aperture angle of the notch and the angle between its bisecting line and the direction of the crack. Here we identify the universal functions of the two angles just mentioned which appear in these formulae, by considering the model problem of an infinite body endowed with a notch with straight boundaries and a straight crack of unit length. The treatment uses Muskhelishvili's complex potentials formalism combined with some conformal mapping. The solution is expressed in the form of an infinite series involving an integral operator, which is evaluated numerically. Application of Goldstein and Salganik's principle of local symmetry then leads to prediction of the kink angle of the crack extension. It is found that although the direction of the crack is closer to that of the bisecting line of the notch after kinking than before it, the kink angle is not large enough for the crack tip to get closer to this line after kinking, except perhaps in some special situations. (10.1023/A:1007637416241)
  DOI : 10.1023/A:1007637416241
• 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.
• Second-order and affine estimates for the behaviour of viscous polycrystals
  
  • Bornert Michel
  • Masson Renaud
  • Ponte-Castañeda P.
  Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik, Wiley-VCH Verlag, 2000, 80, pp.S17-S20. The recently proposed second‐order and affine estimates for the effective behavior of nonlinear heterogeneous materials rely on the same linearization procedure and refer to some “thermoelastic comparison composite”. But both approaches differ in the way the overall nonlinear answer is defined, either through average stress‐strain relations or energy considerations. When combined with the linear self‐consistent model, they provide new tools for the predictions of the behavior of viscoplastic polycrystals (steady state creep). They are compared to each other and to other more classical estimates (incremental and tangent) in the following situations.: a 2D antiplane model problem for which efficient rigorous upper bounds are available, the creep of isotropic aggregates of FCC crystals and HCP crystals with different critical stresses on the basal and prismatic slip systems. (10.1002/zamm.20000801305)
  DOI : 10.1002/zamm.20000801305
• Stability and Nonlinear Solid Mechanics
  
  • Nguyen Quoc Son
  , 2000, pp.416 pages. Although the problem of stability and bifurcation is well understood in Mechanics, very few treatises have been devoted to stability and bifurcation analysis in dissipative media, in particular with regard to present and fundamental problems in Solid Mechanics such as plasticity, fracture and contact mechanics. Stability and Nonlinear Solid Mechanics addresses this lack of material, and proposes to the reader not only a unified presentation of nonlinear problems in Solid Mechanics, but also a complete and unitary analysis on stability and bifurcation problems arising within this framework. Main themes inlude : . elasticity and plasticity problems in small and finite deformation . general concepts of stability and bifurcation and basic results . elastic buckling . plastic buckling of structures . standard dissipative systems obeying maximum dissipation. These themes are developped in 20 chapters and illustrated by various analytical and numerical results. The coverage given here extends beyond the limited boundaries of previous works, resulting in a text of lasting interest and value to postgraduate students, researchers and practitioners working in mechanical, civil and aerospace engineering, as well as materials science.
• Behaviour characterisations of sheet metals, metallic honeycombs and foams at high and medium strain rates
  
  • Zhao H.
  • Gary G.
  Key Engineering Materials, Trans Tech Publications, 2000, 177-180, pp.225-230. This paper deals with dynamic testing and modelling of the metallic materials and soft structural material made of metals such aluminium honeycombs and foams. Tests are performed with the SHPB (Split Hopkinson Pressure Bar) system which is frequently used in a range of strain rates which correspond to those involved in most of civil industrial applications. Improvements of the SHPB were necessary in order to obtain reliable results on soft structural materials. Some experimental results and their modelling for metals as well as for aluminium honeycombs and foams wil1 be presented. (10.4028/www.scientific.net/KEM.177-180.225)
  DOI : 10.4028/www.scientific.net/KEM.177-180.225
• Effets d'un préécrouissage ou d'un surécrouissage cyclique sur la durée de vie en fatigue de divers aciers, à contrainte ou déformation imposée.
  
  • Doquet Véronique
  • Taheri Said
  Revue Française de Mécanique, 2000, 1, pp.27-33.
• Study of the mechanical behaviour of plasma deposited silica films on polycarbonates and steel
  
  • Hofrichter Alfred
  • Constantinescu Andrei
  • Benayoun Stéphane
  • Bulkin Pavel
  • Drévillon Bernard
  Journal of Vacuum Science & Technology A, American Vacuum Society, 2000, 18, pp.2012-2014. In the present study, we deposited amorphous hydrogenated silicon oxide films on polycarbonate, stainless steel, and silicon by plasma enhanced chemical vapor deposition using a low pressure, high density integrated distributed electron cyclotron resonance plasma reactor. Substrate curvature, vibrating slab, and Vickers indentation experiments were used to evaluate the intrinsic stress, the Young modulus of the films, and the composite hardness of the film–substrate system. The indentation experiments were modeled by finite element analysis and the calculated values were compared to experimentally measured hardness values. A reasonable accordance with the experiment was found both for stainless-steel and polycarbonate substrates, indicating that the modeling is valid and may be used to enhance the interpretation of the indentation experiments. The calculations show an important bending of the film in the noncontact region in the case of a Vickers indentation on a coated polycarbonate sample. The analysis of the thus-induced strain distribution in the coating indicates that the measured diagonal might be overestimated and not representative of the real contact area. The calculations indicate that the yield limit of the plasma-deposited silica films is of about 4 GPa. (10.1116/1.582464)
  DOI : 10.1116/1.582464
• An inverse approach to determine the non-linear properties of induction heat-treated steels
  
  • Niclas André
  • Bourgeois Lament
  European Journal of Mechanics - A/Solids, Elsevier, 2000, 19, pp.69-88. The identification of the through-the-thickness variation of the non-linear properties of a steel structure due to a heat treatment by induction is considered. An inverse approach to that problem is proposed, which is based on a 4-point bending test of a heat-treated parallelepipedic bar. It includes a layer-removal method for measuring residual stresses. Precisely, two different inverse methods are described. For a medium carbon steel, an application based on experimental data is performed, which shows the efficiency of our approach and a good agreement between the two methods. (10.1016/S0997-7538(00)00152-2)
  DOI : 10.1016/S0997-7538(00)00152-2
• Stabilité et Mécanique Non linéaire
  
  • Nguyen Quoc Son
  , 2000, pp.461 pages. Stabilité et mécanique non linéaire présente deux aspects fondamentaux de la mécanique non linéaire des solides : l'analyse de réponse statique et l'analyse de stabilité des matériaux et des structures. Il s'agit d'une approche synthétique des notions de base et des principaux résultats concernant l'évolution quasi-statique, la stabilité et la bifurcation des systèmes réversibles ou dissipatifs usuels. Elle concerne par exemple les solides élastiques, élasto-plastiques ou visco-plastiques en petite ou en grande transformation, ces solides étant soumis à des chergements mixtes classiques ou à des conditions de contact unilatéral avec frottement, ou comportant des propagations de fissures internes. L'ouvrage présente les derniers développements de la modélisation des solides en liaison avec les apports de la thermodynamique et de l'analyse convexe. Bon nombre de ces résultats sont issus des travaux de recherche récents du Laboratoire de Mécanique des Solides de l'Ecole Polytechnique. il s'adresse plus particulièrement aux enseignants, aux chercheurs, aux ingénieurs et lecteurs avertis cherchant une approche variationnelle privilégiant l'esprit mécanique. Il fait le lien entre les ouvrages de mécanique de style classique et les traités mathématiques peu adaptés au contexte de la mécanique des solides. Quoc Son Nguyen est directeur de recherche au CNRS et auteur d'une centaine de publications scientifiques. Ses travaux au sein du Laboratoire de Mécanique des Solides (Ecole Polytechnique) portent essentiellement sur la plasticité, la rupture et la stabilité.
• Evaluation of fatigue-ratcheting damage of a pressurized elbow undergoing damage seismic inputs
  
  • Dang Van Ky
  • Moumni Ziad
  Nuclear Engineering and Design, Elsevier, 2000, 176, pp.41-50. We present a simplified method to calculate the plastic ratchet of elbow-shaped pipes submitted to seismic loading and an internal pressure. This method is simplified in the sense that the value of the ratchet is obtained without the use of finite element method (FEM) calculations. Here we derive a formula and use it to evaluate the fatigue-ratcheting damage of an elbow. This approach is applicable to complex plastic response appropriately described by non-linear kinematics hardening, which is more realistic for stainless steel such as 316-L. (10.1016/S0029-5493(99)00229-0)
  DOI : 10.1016/S0029-5493(99)00229-0
• A Concept for Earthquake-Resistant Design of Underground Structures: Stress Response Spectrum
  
  • Kurose Ayumi
  • Bérest Pierre
  , 2000, pp.1043-1049. This paper introduces a method to evaluate the mechanical effects induced in the cross-section of an underground structure, constructed in a medium of great thickness, under earthquake ground motion. Damage observations after large earthquakes (e.g., Kobe, 1995) have shown the cross-sectional vulnerability of underground structures at shallow or great depth. Present earthquake-resistant design standards only suggest calculation methods for structures constructed in a soil laying over a rigid basement and cannot be applied to a structure constructed in a medium of great thickness, such as a tunnel, an underground hydrocarbon storage facility or a nuclear-waste disposal site. Thus, development of a systematic method to evaluate the seismic effects induced in the cross-section of a structure in an unbounded medium is of interest. The approach proposed here is conceptually similar to that used for earthquake response analysis of buildings: using a simple but realistic model of an underground linear structure (a 2D cavity with circular cross-section in an infinite, elastic, linear, homogeneous and isotropic medium) and real earthquake records, we propose a response spectrum more suitable, than the usual velocity or acceleration response spectrum, for analyzing the structural stability of underground construction during earthquakes: the Stress Response Spectrum (SRS), which is defined as the maximum value of the maximum shear stress at the cavity wall during the duration of ground motion. The SRS values are computed by using 21 earthquake motions (provided by the Japan Meteorological Agency) of magnitude higher than 4, which were recorded by the Japan Nuclear Cycle Research Institute (JNC) in a 315-meter deep gallery excavated in an a granodioritic rock mass at the Kamaishi Mine in Iwate, Japan. In light of the numerical analysis, the SRS appears to be a potential tool for the earthquake-response analysis of underground structures. The Stress Response Spectrum will provide engineers with the order of magnitude of mechanical effects in an underground structure for a given earthquake motion; conversely, for a given target SRS, may assist in producing a design earthquake more suitable for analysis of deep underground structures than those currently available.
• Computational and experimental investigations of the local strain field in elastoplastic two-phase materials
  
  • Doumalin Pascal
  • Bornert Michel
  • Soppa Ewa
  , 2000, pp.323-328.
• Dissipation intrinsèque d'un matériau sableux
  
  • Luong M. P.
  , 2000, pp.127-132. No abstract provided
• Simulation expérimentale du risque en génie civil
  
  • Luong M. P.
  , 2000, pp.77-106. No abstract provided
• Micromechanical applications of digital image correlation techniques
  
  • Doumalin P.
  • Bornert Michel
  , 2000, pp.67-74. No abstract provided
• Thermodynamical description of moving discontinuities : application to fracture and wear
  
  • Stolz C.
  , 2000, pp.1463-1468. No abstract provided
• Solid-fluid phase transformation within grain boundaries
  
  • Leroy Yves M
  • Ghoussoub Joumana
  , 2000. 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