Publications

2005

• Simulations and microstructural effects on macroscopic mechanical behavior and local strain and stress field heterogeneities. Application to zirconium alloys
  
  • Bertolino G.
  • Bilger N.
  • Crépin Jérôme
  • Dexet M.
  • Héripré E.
  , 2005. No abstract provided
• Thermodynamics of rate-independent plasticity
  
  • Puglisi Giuseppe
  • Truskinovsky Lev
  Journal of the Mechanics and Physics of Solids, Elsevier, 2005, 53, pp.655-679. We show that the singular dissipative potential of the phenomenological rate-independent plasticity can be obtained by homogenization of a micro-model with quadratic dissipation. The essential ingredient making this reduction possible is a rugged energy landscape at the micro-scale, generating under external loading a regular cascade of subcritical bifurcations. Such landscape may appear as a result of a sufficiently strong pinning or jamming of defects, leading to elastic micro-metastability. The rate-independent plastic deformation emerges in this description as a continuous succession of infinitesimal viscous events; the limiting procedure presumes the elimination of small time and length scales. We present an explicit example of a simple viscoelastic mass-spring system whose macroscopic dissipative behavior is plastic, rate independent. (10.1016/j.jmps.2004.08.004)
  DOI : 10.1016/j.jmps.2004.08.004
• Identification d'obstacles en acoustique dans des domaines tridimensionnels bornés
  
  • Nemitz Nicolas
  • Bonnet Marc
  , 2005, pp.437-442. Cette communication concerne l’identification d’obstacles dans un domaine acoustique tridimensionnel borné. L’approche présentée repose sur deux ingrédients essentiels. Le premier est l’utilisation d’une méthode d’équations intégrales rapide fondée sur la fast multipole method, grâce à laquelle il est possible d’aborder ce type de problème d’inversion sur des configurations tridimensionnelles bornées de longueurs caractéristiques relativement grandes par rapport à la longueur d’onde acoustique. Le second est le gradient topologique de la function coût associée au problème inverse, permettant de déterminer les zones du domaine acoustique dans lesquelles l’introduction virtuelle d’un obstacle infinitésimal induit une diminution de la fonction coût. Cela permet par exemple de guider le choix de conditions initials pour la mise en oeuvre ultérieure d’un algorithme d’inversion reposant sur l’optimisation de la function coût. Ces deux aspects sont présentés et illustrés sur des exemples numériques. (10.3166/remn.15.307-318)
  DOI : 10.3166/remn.15.307-318
• Evaluation précise des procédures de linéarisation en homogénéisation non linéaire
  
  • Rekik Amna
  • Bornert Michel
  • Auslender F.
  • Zaoui André
  , 2005.
• Small-inclusion asymptotic for inverse problems in acoustics
  
  • Bonnet Marc
  , 2005.
• Small-obstacle expansion in 3-d inverse scattering
  
  • Bonnet Marc
  , 2005.
• Topological sensitivity techniques for 3D elastic and acoustic inverse scattering
  
  • Bonnet Marc
  , 2005. (10.1016/j.cma.2005.10.026)
  DOI : 10.1016/j.cma.2005.10.026
• Multi-scale characterization and modelling of human cortical bone.
  
  • Ho Ba Tho M.C.
  • Stolz Claude
  • Vanleene M.
  • Bensamoun S.
  • Treutenaere J.M.
  • Rey C.
  , 2005.
• Giens 2005
  
  • Allix Olivier
  • Bonnet Marc
  • Grellier Jean-Paul
  • Ohayon Roger
  • Rassineux Alain
  , 2005. Le calcul des structures est un domaine de recherches et d’applications industrielles en perpétuel développement. Son objet est la modélisation et la simulation numérique des comportements, en espace et en temps, des structures interagissant avec un environnement passif ou actif. Du fait de la croissance rapide des performances des ordinateurs, des problèmes autrefois inabordables sont maintenant étudiés : variabilité, problèmes multiphysiques, multiéchelles.</br></br> Tous les deux ans, l’association CSMA organise un colloque national en calcul des structures et la prise en charge de cette septième édition a été confiée au Laboratoire Roberval de Mécanique de l’Université de Technologie de Compiègne.</br></br> Le Comité Scientifique a retenu 180 communications réparties sur quatre sessions parallèles, une session « poster » et une session logiciel. En outre, nous avons invité le groupe pour l'Avancement des Méthodes Numériques de l'Ingénieur (GAMNI), qui présentera ses travaux dédiés à l'optimisation.</br></br> Le Colloque de « Giens » est un événement majeur, quasi incontournable pour la communauté de la mécanique numérique, académique et industrielle, un lieu de rencontre et d’échanges privilégiés entre les chercheurs, jeunes et plus confirmés, et les ingénieurs de l’industrie. Nous souhaitons que cette septième édition du Colloque soit digne des précédentes.</br></br> Le Comité d'Organisation remercie tous les participants et exprime sa gratitude au Comité scientifique et aux membres des institutions, entreprises et organismes de recherche qui ont œuvré au succès de ce septième Colloque.</br></br> Il est possible de consulter la collection <a href="https://hal.science/CSMA2005">CSMA2005</a> correspondante.
• Contraintes résiduelles dans les éprouvettes cylindriques
  
  • Bérest Pierre
  • Vouille Gérard
  Revue française de Géotechnique, edp sciences, 2005, 110, pp.41-50. On attribue fréquemment aux « contraintes résiduelles » ou « contraintes internes » diverses manifestations anormales observées dans les massifs rocheux ou sur des carottes prélevées en profondeur. Pour décrire ces phénomènes on considère une loi de comportement élastique linéaire présentant des « déformations initiales » non compatibles. Les contraintes résiduelles ne dépendent alors que de la forme de l’objet considéré, des paramètres élastiques et du tenseur d’incompatibilité (ou tenseur de Ricci) associé aux déformations initiales. En supposant que ce tenseur est constant dans une petite éprouvette cylindrique prélevée dans le massif rocheux, on établit la forme générale des champs de contrainte résiduelle qui peuvent affecter l’éprouvette. (10.1051/geotech/2005110041)
  DOI : 10.1051/geotech/2005110041
• Modelling's tyre's wear : a local approach
  
  • Delattre Benoit
  • Pradeilles-Duval Rachel-Marie
  • Stolz Claude
  , 2005.
• Proposition of a general yield function in geomechanics
  
  • Maïolino Siegfried
  Comptes Rendus. Mécanique, Académie des sciences (Paris), 2005, 333, pp.279-284. A general smooth and convex yield function is proposed, able to model the particular behavior of geomaterials, particularly rock materials that are characterized by a linear or parabolic Mohr's envelope, and a particular shape in the deviatoric plane. These characteristics are defined by two functions: the equation of the criterion in the meridian plane and the extension ratio, which are integrated in a general equation ensuring convexity and smoothness of the yield function, whatever the characteristic functions. This expression is interesting, because it allows a straightforward development of a constitutive model based on triaxial tests, in extension and compression. It also allows the development of smooth criteria corresponding to the Mohr–Coulomb criterion and the Hœk–Brown criterion, the latter typical of rock mechanics. (10.1016/j.crme.2004.11.008)
  DOI : 10.1016/j.crme.2004.11.008
• El Método Multipolo Rápido para la Aceleración del Método de los Elementos de Contorno en Elastodinámica Isótropa 3D.
  
  • Sanz J. A.
  • Bonnet Marc
  • Saez A.
  , 2005. No abstract provided
• Quasicontinuum modelling of short-wave instabilities in crystal lattices
  
  • Truskinovsky Lev
  • Vainchtein Anna
  Philosophical Magazine, Taylor & Francis, 2005, 85, pp.4055-4065. We propose a hybrid quasicontinuum model which captures both long and short-wave instabilities of crystal lattices and combines the advantages of weakly non-local (higher gradient) and strongly non-local (integral) continuum models. To illustrate the idea, we study the simplest one-dimensional lattice exhibiting commensurate and incommensurate short-wave instabilities. We explicitly compute stability limits of the homogeneous states using both discrete and quasicontinuum models. The new quasicontinuum approximation is shown to be capable of reproducing a detailed structure of the discrete stability diagram. (10.1080/14786430500363270)
  DOI : 10.1080/14786430500363270
• Very slow creep tests on rock samples
  
  • Bérest Pierre
  • Antoine Blum Pierre
  • Pierre Charpentier Jean
  • Gharbi Hakim
  • Valès Frédéric
  International Journal of Rock Mechanics and Mining Sciences, Pergamon and Elsevier, 2005, 42 (4), pp.569-576. Long-term creep tests have been performed on rock-salt and argillite samples under very small uniaxial loadings (σ = 0.02 to 0.1 MPa) . To minimize the effects of temperature variations, testing devices were set in a mine where temperature fluctuations are of the order of one-hundredth of a degree Celsius. The mechanical loading was provided by dead weights. The deformations were measured through special displacement sensors with a resolution of ∆ε = 10-8. Strain rates as small as έ = 7 × 10-13s-1 were measured. These tests allow rock-sample creep to be investigated at very small strain rates. The tests also prove that extrapolation of constitutive laws at very small rates is often incorrect. (10.1016/j.ijrmms.2005.02.003)
  DOI : 10.1016/j.ijrmms.2005.02.003
• Infrared vibrothermography of sand
  
  • Luong Minh-Phong
  , 2005, pp.1-8. The paper introduces infrared thermography as a non-contact and non-destructive technique that conveniently offers the possibility of evaluating the energy-dissipating ability of soil, generally difficult to be determined using traditional techniques. It allows records and observations in real time of heat patterns produced by the dissipation of energy caused by friction between grains. Such dissipative heat occurs when soil is subjected to vibratory loading exceeding the characteristic threshold, and it evidences the distortion mechanism. This energy dissipation mechanism influences the wave propagation, intergranular attenuation, and dispersion through particles contacts. The infrared thermographic technique, which couples mechanical and thermal energy, offers the potential of directly monitoring the stress state of particle rearrangement and predicting the macroscopic mechanical response of soils subjected to cyclic, dynamic or vibratory loading. In addition, infrared thermography evidences the fuse effect of soil, capable to mitigate significantly the earthquake loading on engineering structures.
• Mechanics and Materials: some aspects and trends of current research
  
  • Zaoui A.
  , 2005.
• Experimental investigation of strain, damage and failure of hydrided zirconium alloys with various hydride orientations
  
  • Racine Aude
  • Bornert Michel
  • Sainte Catherine Claude
  • Cappelaere Chantal
  • Caldemaison Daniel
  , 2005.
• Inférence dans les HMM hiérarchiques et factorisés: changement de représentation vers le formalisme des réseaux bayésien
  
  • Gelly Sylvain
  • Bredeche Nicolas
  • Sebag Michèle
  , 2005, pp.pp.35-44. This short paper deals with extending HMM with both hierarchical and factorial features. A new inference algorithm is proposed to deal with such a representation that is based on a representation change towards bayesian network representation formalism.
• Ductile fracture of synthetic anorthite aggregates deformed to large strain in torsion.
  
  • Rybacki Erik
  • Dimanov Alexandre
  • Dresen Georg
  , 2005.
• Étude de stabilité d’un solide sous frottement de glissement par optimisation de la surface de contact
  
  • Lorang Xavier
  • Bonnet Marc
  • Nguyen Qoc Son
  , 2005. On s’intéresse à la dynamique d’un disque élastique en glissement stationnaire par rapport à un solide rigide. Il a été démontré pour le disque en rotation uniforme et pour un coefficient de frottement donné que l’équilibre glissant est instable. L’étude numérique de la stabilité se traduit par la résolution d’un problème aux valeurs propres généralisées. L’objet de cette communication est de présenter une méthode permettant d’évaluer la sensibilité de la valeur propre par rapport à la géométrie de la surface de contact et de définir un algorithme permettant de trouver la surface de contact optimale afin de stabiliser un mode précis. La méthode de calcul de la sensibilité est illustrée sur un exemple simple afin de la valider. Ce travail s’inscrit à long terme dans une optique de réduction du phénomène de crissement des freins à disque.
• Kinematics of syn-eclogite deformation in the Bergen Arcs, Norway, implications for exhumation mechanisms
  
  • Raimbourg Hugues
  • Jolivet Laurent
  • Labrousse Loic
  • Leroy Yves
  • Avigad Dov
  Special Publication - Geological Society of London, 2005, 243, pp.175-192. The northwestern part of Holsnøy island, in the Bergen Arcs, Norway, consists of a granulite-facies protolith partially transformed at depth in eclogite (700 °C, > 19 kbars) and amphibolite (650 °C, 8-10 kbars) facies during the Caledonian orogenesis. Eclogitized zones are mainly planar objects (fractures with parallel reaction bands and cm-to-100 m-scale shear zones). Eclogitic zones are distributed in two sets of orientations and the associated deformation can be described as 'bookshelf tectonics'. The major shear zones strike around N120 and dip to the North, and show consistent top-to-the-NE shear sense throughout the area. In the large-scale kinematic frame of Caledonian NW-dipping slab, eclogitic shear zones are interpreted as the way to detach crustal units from the subducting slab and to prevent their further sinking. As the retrograde amphibolitic deformation pattern is similar to the eclogitic one, the detached crustal units started their way up along these eclogitic shear zones. Radiometric ages of eclogitic and amphibolitic metamorphism and their comparison with the chronology of Caledonian orogenesis show that the deformation recorded on Holsnøy occurred in a convergent context. The mechanism we propose can thus account for the first steps of exhumation during collision. (10.1144/GSL.SP.2005.243.01.13)
  DOI : 10.1144/GSL.SP.2005.243.01.13
• Rheology of synthetic anorthite-diopside aggregates: Implications for ductile shear zones
  
  • Dimanov Alexandre
  • Dresen Georg
  Journal of Geophysical Research : Solid Earth, American Geophysical Union, 2005, 110. We investigated the high‐temperature creep strength of fine‐grained anorthite‐diopside rocks at temperatures ranging from 1323 K to 1523 K and at 300 MPa confining pressure in a Paterson‐type gas‐medium deformation apparatus. Flow stress varied between 20 and 450 MPa resulting in strain rates between 6.1 × 10−7 s−1 and 7.5 × 10−4 s−1. Pure diopside and anorthite samples were hot pressed from crushed natural single crystals and glass powders, respectively. Two‐phase samples were produced by hot isostatic pressing of mechanically mixed powders of anorthite glass with 25, 50 and 75 vol % diopside particles. Arithmetic mean grain size of the anorthite matrix is dAn ≈ 3.5 μm. Three different ranges of diopside particle size were used: dDi < 25 μm, <35 μm, and <45 μm. Water content of as is samples was about 0.05 ± 0.02 wt % H2O, and predried samples contain about 0.004 ± 0.001 wt % H2O. At experimental conditions, as is samples are assumed to be water saturated. Water content of predried samples is about 3 times less than that of starting diopside single crystals. The specimens contain about 1 vol % glass located at fluid inclusions and some multiple grain junctions. Two‐grain boundaries examined by high‐resolution transmission electron microscopy did not show amorphous layers to a resolution of 1 nm. At experimental conditions, pure diopside aggregates are about 2–3 orders of magnitude stronger than pure anorthite samples for as is and predried specimens, respectively. In general, strength of the two‐phase aggregates increases with increasing diopside content but remains between isostress and isostrain rate bounds. Aggregate strengths predicted from continuum mechanics models are in good agreement with the experimental data for dilute diopside particle mixtures and high‐volume fractions, when diopside particles form a load‐bearing framework. At low stresses (<100–200 MPa) the stress exponent is n ≈ 1, suggesting diffusion‐controlled creep. At higher stresses, mechanical data and microstructures suggest that samples deformed in the transition region between diffusion‐controlled creep and dislocation creep. For pure anorthite and diopside aggregates deforming in dislocation creep we estimated stress exponents of n ≈ 3 and n ≈ 5.5, respectively. For the two‐phase aggregates, n is between n ≈ 3 and n ≈ 5, depending on diopside content. At low stresses, deformation microstructures indicate load transfer from a weak anorthite matrix to stronger diopside particles. Creep activation energies for pure diopside and anorthite mixtures range from 286 kJ mol−1 for wet anorthite deformed at low stresses to 691 kJ mol−1 for dry diopside deformed at high stresses. Activation energies of two‐phase mixtures are between or close to those of the end‐members. As is samples have significantly lower activation energies than predried samples. (10.1029/2004JB003431)
  DOI : 10.1029/2004JB003431
• On the Identification of multiscale crystal plasticity models of Titanium Aluminides
  
  • Roos A.
  • Thomas M.
  • Héripré E.
  • Crépin Jérôme
  • Chaboche J. L.
  , 2005. No abstract provided
• Effect of a nonuniform distribution of voids on the plastic response of voided materials: a computational and statistical analysis
  
  • Bilger Nicolas
  • Auslender François
  • Bornert Michel
  • Michel Jean-Claude
  • Moulinec Hervé
  • Suquet Pierre
  • Zaoui André
  International Journal of Solids and Structures, Elsevier, 2005, 42, pp.517-538. This study investigates the overall and local response of porous media composed of a perfectly plastic matrix weakened by stress-free voids. Attention is focused on the specific role played by porosity fluctuations inside a representative volume element. To this end, numerical simulations using the Fast Fourier Transform (FFT) are performed on different classes of microstructure corresponding to different spatial distributions of voids. Three types of microstructures are investigated: random microstructures with no void clustering, microstructures with a connected cluster of voids and microstructures with disconnected void clusters. These numerical simulations show that the porosity fluctuations can have a strong effect on the overall yield surface of porous materials. Random microstructures without clusters and microstructures with a connected cluster are the hardest and the softest configurations, respectively, whereas microstructures with disconnected clusters lead to intermediate responses. At a more local scale, the salient feature of the fields is the tendency for the strain fields to concentrate in specific bands. Finally, an image analysis tool is proposed for the statistical characterization of the porosity distribution. It relies on the distribution of the ‘distance function’, the width of which increases when clusters are present. An additional connectedness analysis allows us to discriminate between clustered microstructures. (10.1016/j.ijsolstr.2004.06.048)
  DOI : 10.1016/j.ijsolstr.2004.06.048