Publications

2005

• 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
• 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.
• Mechanics and Materials: some aspects and trends of current research
  
  • Zaoui A.
  , 2005.
• 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
• IABEM 2004
  
  • Crouch S. L.
  • Bonnet Marc
  , 2005.
• Inverse acoustic scattering by small-obstacle expansion of cost function
  
  • Guzina B. B.
  • Bonnet Marc
  , 2005. No abstract provided
• A methodology for seismic vulnerability of masonry arch bridge walls
  
  • Rota M.
  • Pecker Alain
  • Bolognini D.
  • Pinho R.
  Journal of Earthquake Engineering, Taylor & Francis, 2005, 9, special issue 2, pp.331-353. Notwithstanding its potential high level, the seismic vulnerability of masonry arch bridges has yet to completely perceived, possibly due to the relatively scarce damage evidence collected after recent eathquakes. The dearth of research studies on this topic is thus one of the main motivations behind the current endeavour, which aims at a better understanding of the dynamic interaction between the arch walls and the filling material of typical masonry arch bridges, and the consequent susceptibility of the latter to out-of-plane collapse mechanisms. Within this framework, a numerical model for the evaluation of the seismic out-of-plane capacity of bridge walls, including the effects of the infill material, is proposed. This methodology can be subdivided into three main components; computation of static earth pressure, eveluation of dynamic soil thrust, assesment of out-of-plane capacity of masonry wall. In addition, a congruent and relatively simple procedure for the estimation of the seismic demand on the arch wall is described. Finally, a parametric study is carried out with a view to appraise the seismic vulnerability associated to typical masonry arch bridge typologies.
• The non-local generalized standard approach: a consistent gradient theory
  
  • Nguyen Quoc Son
  • Andrieux Stephane
  Comptes Rendus. Mécanique, Académie des sciences (Paris), 2005, 333, pp.139-145. In this paper, the generalized standard approach is proposed as a consistent gradient theory to include the gradients of the temperature and of the internal parameter in the set of state variables. This theory is derived from a global point of vue developping the basic ideas of continuum thermodynamics. It leads to the appropriate expressions of the entropy and of the internal energy in terms of the free energy in the case of temperature gradient. The local governing equations of the proposed thermodynamical approach are derived. The formalism of the dissipation potential can be applied in the same spirit as in the classical description from the dissipation analysis. (10.1016/j.crme.2004.09.010)
  DOI : 10.1016/j.crme.2004.09.010
• The Reciprocity Gap Functional for Identifying Defects and Cracks
  
  • Bui Huy Duong
  • Constantinescu Andrei
  • Maigre Hubert
  , 2005, 469, pp.17-54. The recovery of defects and cracks in solids using overdetermined boundary data, both the Dirichlet and the Neumann types, is considered in this paper. A review of the method for solving these inverse problems is given, focusing particularly on linearized inverse problems. It is shown how the reciprocity gap functional can solve nonlinear inverse problems involving identification of cracks and distributed defects in bounded solids. Exact solutions for planar cracks in 3D solids are given for static elasticity, heat diffusion and transient acoustics. (10.1007/3-211-38134-1_2)
  DOI : 10.1007/3-211-38134-1_2
• Prise en compte des contraintes résiduelles de traitement thermique dans la prédiction de la tenue en service des culasses en aluminium
  
  • Comte Frédéric
  • Nguyen-Tajan Thi Mac-Lan
  • Morin Nicolas
  • Maitournam Habibou
  • Moumni Ziad
  Mechanics & Industry, EDP Sciences, 2005, 6, pp.343-348. Cet article porte sur la modélisation des culasses aluminium de moteurs diesel HDI en vue de prédire leur tenue en fatigue polycyclique. Celles-ci, avant d'être frettées, serrées sur le bloc moteur et utilisées en service, subissent un traitement thermique (trempe et revenu) afin d'améliorer leurs propriétés mécaniques. Lors de ce procédé d'importantes contraintes résiduelles sont générées. Leur modélisation est nécessaire pour obtenir des résultats numériques prédictifs. Une première difficulté vient de la modélisation des échanges thermiques. Pour cela, le choix d'une fonction analytique simple pour le coefficient d'échange H = f(Tparoi), suivi de l'optimisation des différents paramètres, a permis de modéliser les courbes de refroidissement. Une fois l'histoire thermique de la culasse modélisée, un calcul mécanique élastoplastique permet de déterminer les contraintes résiduelles. Celles-ci, fortement de traction dans la zone à risque, sont défavorables à la tenue à la fatigue polycyclique de la pièce dans le cas de la trempe à l'eau. La prise en compte de l'état résiduel de fin de traitement thermique dans la filière de dimensionnement à la fatigue polycyclique permet alors de caractériser les zones à risque expérimentalement observées. (10.1051/meca:2005039)
  DOI : 10.1051/meca:2005039
• A kinematic interaction model for a large-diameter shaft foundation. An application to seismic demand assessment of a bridge subject to coupled swaying-rocking excitation.
  
  • Beltrami Carlo
  • Lai Carlo G.
  • Pecker Alain
  Journal of Earthquake Engineering, Taylor & Francis, 2005, 9, special issue 2, pp.355-393. The aim of this paper is to illustrate an analytical model for the assessment of kinematic interaction of large-diameter shaft foundations. The model is derived using recently obtained solutions of soil structure interaction problems of rigid walls and fixed base cylinders subjected to a dynamic excitation. The proposed model constitutes an extension to a deformable base of the elastodynamic solution of a rigid fixed-base cylinder imbedded in a homogeneous or inhomogeneous soil stratum with different lateral boundary conditions. The analytical model has been validated by means of a finite elements code and it has been implemented in a consistent seismic soil-structure-interaction analysis procedure. An application of the model to a long, multispan continuous prestressed concrete viaduct with tall piers has been carried out focusing on the importance of kinematic interaction. The main result is that the foundation input motion is characterised not only by a translational horizontal component which is usually of a reduced amplitude if compared with the free-field ground motion, but also by a rotation component that is responsible for a large seismic demand in the superstructure. The proposed model represents an effective tool to be used in the engineering practice to assess both the seismic actions induced by the ground shaking on the foundation system and the effective input motion of a superstructure founded on massive and large diameter shafts
• An exact inversion formula for determining a planar fault from boundary measurements
  
  • Bui Hui Duong
  • Constantinescu Andrei
  • Maigre H.
  Journal of Inverse and Ill-posed Problems, De Gruyter, 2005, 13 (6), pp.553-565. This paper considers the inverse problem of determining a time-dependent slip fault which releases shear stress elastically. The input data for the inverse problem are the accelerations measured on the free external surface. A new formula for determining explicitly the geometry of the planar fault is proposed. Potential applications to real earthquakes are discussed. (10.1515/156939405775199514)
  DOI : 10.1515/156939405775199514
• Softening trigerred by eclogitization, the first step toward exhumation during continental subduction
  
  • Jolivet Laurent
  • Raimbourg Hugues
  • Labrousse Loïc
  • Avigad Dov
  • Leroy Yves
  • Austrheim Håkon
  • Andersen Torgeir B.
  Earth and Planetary Science Letters, Elsevier, 2005, 237, pp.532-547. Direct observation of peak pressure deformation in exhumed subduction channels is difficult because little evidence of this deformation survives later syn-exhumation deformation. Most ultrahigh-pressure parageneses are found in continental derived metamorphic rocks making continental subduction the best context to observe peak pressure deformation. Whereas many studies have enlightened the main driving parameters of exhumation such as buoyancy forces, low viscosity in the subduction channel, overburden removal by erosion and normal faulting, a basic question is seldom considered: why is a tectonic unit disconnected from the descending lithosphere and why does it start its way towards the surface? This event, seminal to exhumation processes, must involve some deformation and decoupling of the exhumed slice from the descending slab at peak pressure conditions or close to it. Our field observations in the Bergen arc show that Caledonian eclogitization and later amphibolitization of a granulitic terrane was achieved with a consistent component of simple shear compatible with the sense of the Caledonian subduction. Thus, the sequence of deformation preserved in the Bergen Arc documents the decoupling of subducted crustal material from the descending slab at the onset of exhumation. This observation suggests that deformation in the subduction channel is largely controlled by kinematic boundary conditions, i.e. underthrusting of the subducting slab. In this context of simple shear, metamorphic reactions assisted by fracturating, fluid infiltration and ductile deformation lower the resistance of rocks and allow the localisation of shear zones and the decoupling of buoyant tectonic units from the subducting slab. These tectonic units can then be incorporated into the channel circulation and start their upward travel. (10.1016/j.epsl.2005.06.047)
  DOI : 10.1016/j.epsl.2005.06.047
• A constitutive model for the fatigue life prediction of rubber
  
  • Raoult Ida
  • Stolz Claude
  • Bourgeois Myriam
  , 2005.
• Modèles de comportement stabilisé anisotrope pour les élastomères
  
  • Raoult Ida
  • Stolz Claude
  • Bourgeois Myriam
  • Nguyen Thi Mac Lan
  • Thomas Jean Jacques
  , 2005.
• Sensitivity analysis for parameter identification in quasi-static poroelasticity
  
  • Lecampion Brice
  • Constantinescu Andrei
  International Journal for Numerical and Analytical Methods in Geomechanics, Wiley, 2005, 29 (2), pp.163-185. This paper is devoted to the formulation of the direct differentiation method and adjoint state method in quasi‐static linear poroelasticity. We derive the strong and weak formulation of both methods and discuss their solutions using the finite element method. The techniques are illustrated and tested on two numerical examples for the case of isotropic and homogeneous material. The presented formulations can be extended to more complex behaviour in poromechanics. (10.1002/nag.409)
  DOI : 10.1002/nag.409
• Dix ans d'acoustique musicale
  
  • Boutillon Xavier
  • Gilbert Joel
  • Vergez Christophe
  Acoustique et Techniques : trimestriel d'information des professionnels de l'acoustique, Neuilly-sur-Seine : Centre d'information et de documentation sur le bruit, 2005, 42-43, pp.1.
• Extracting constitutive parameters from full-field measurements: a review of identification methods
  
  • Bonnet Marc
  • Grediac Michel
  • Hild François
  • Pagano Stéphane
  • Avril Stéphane
  • Pierron Fabrice
  , 2005.