Publications

2005

• Fluid structure interaction problems in large deformation
  
  • Le Tallec Patrick
  • Gerbeau Jean-Frédéric
  • Hauret Patrice
  • Vidrascu Marina
  Comptes Rendus. Mécanique, Académie des sciences (Paris), 2005, 333, pp.910-922. The present article deals with the simulation of fluid structure interaction problems in large deformation, and discusses two aspects of their numerical solution: (i) the derivation of energy conserving time integration schemes in presence of fluid structure coupling, moving grids, and nonlinear kinematic constraints such as incompressibility and contact, (ii) the introduction of adequate preconditioners efficiently chaining local fluid and structure solvers. Solutions are proposed, analyzed and tested using nonlinear energy correcting terms, and added mass based Dirichlet Neumann preconditioners. Numerical applications include nonlinear impact problems in elastodynamics and blood flows predictions within flexible arteries.
• Kinetics of martensitic phase transitions: lattice model
  
  • Truskinovsky Lev
  • Vainchtein Anna
  SIAM Journal on Applied Mathematics, Society for Industrial and Applied Mathematics, 2005, 66, pp.533-553. Martensitic phase transitions are often modeled by mixed-type hyperbolic-elliptic systems. Such systems lead to ill-posed initial-value problems unless they are supplemented by an additional kinetic relation. In this paper we explicitly compute an appropriate closing relation by replacing the continuum model with its natural discrete prototype. The procedure can be viewed as either regularization by discretization or a physically motivated account of underlying discrete microstructure. We model phase boundaries by traveling wave solutions of a fully inertial discrete model for a bi-stable lattice with harmonic long-range interactions. Although the microscopic model is Hamiltonian, it generates macroscopic dissipation which can be specified in the form of a relation between the velocity of the discontinuity and the conjugate configurational force. This kinetic relation respects entropy inequality but is not a consequence of the usual Rankine--Hugoniot jump conditions. According to the constructed solution, the dissipation at the macrolevel is due to the induced radiation of lattice waves carrying energy away from the propagating front. We show that sufficiently strong nonlocality of the lattice model may be responsible for the multivaluedness of the kinetic relation and can quantitatively affect kinetics in the near-sonic region. Direct numerical simulations of the transient dynamics suggest stability of at least some of the computed traveling waves. (10.1137/040616942)
  DOI : 10.1137/040616942
• Du quasi-statique au dynamique rapide avec un unique moyen d'essai
  
  • Gary Gérard
  , 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
• Evaluation précise des procédures de linéarisation en homogénéisation non linéaire
  
  • Rekik Amna
  • Bornert Michel
  • Auslender F.
  • Zaoui André
  , 2005.
• 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
• Small-inclusion asymptotic for inverse problems in acoustics
  
  • Bonnet Marc
  , 2005.
• Small-obstacle expansion in 3-d inverse scattering
  
  • Bonnet Marc
  , 2005.
• 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.
• 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
• Inverse problems in elasticity
  
  • Bonnet Marc
  • Constantinescu Andrei
  Inverse Problems, IOP Publishing, 2005, 21, pp.R1-R50. This review is devoted to some inverse problems arising in the context of linear elasticity, namely the identification of distributions of elastic moduli, model parameters or buried objects such as cracks. These inverse problems are considered mainly for three-dimensional elastic media under equilibrium or dynamical conditions, and also for thin elastic plates. The main goal is to overview some recent results, in an effort to bridge the gap between studies of a mathematical nature and problems defined from engineering practice. Accordingly, emphasis is given to formulations and solution techniques which are well suited to general-purpose numerical methods for solving elasticity problems on complex configurations, in particular the finite element method and the boundary element method. An underlying thread of the discussion is the fact that useful tools for the formulation, analysis and solution of inverse problems arising in linear elasticity, namely the reciprocity gap and the error in constitutive equation, stem from variational and virtual work principles, i.e., fundamental principles governing the mechanics of deformable solid continua. In addition, the virtual work principle is shown to be instrumental for establishing computationally efficient formulae for parameter or geometrical sensitivity, based on the adjoint solution method. Sensitivity formulae are presented for various situations, especially in connection with contact mechanics, cavity and crack shape perturbations, thus enriching the already extensive known repertoire of such results. Finally, the concept of topological derivative and its implementation for the identification of cavities or inclusions are expounded. (10.1088/0266-5611/21/2/R01)
  DOI : 10.1088/0266-5611/21/2/R01
• Fast multipole method applied to the coupling of elastostatic BEM with FEM
  
  • Margonari M.
  • Bonnet Marc
  Computers & Structures, Elsevier, 2005, 83, pp.700-717. BEM–FEM coupling is desirable for three-dimensional problems involving specific features such as (i) large or unbounded media with linear constitutive properties, (ii) cracks, (iii) critical parts of complex geometry requiring accurate stress analyses. However, for cases with a BEM discretization involving a large number NBEM of degrees of freedom, setting up the BEM contribution to the coupled problem using conventional techniques is an expensive $O(NBEM^{2})$ task. Moreover, the fully-populated BEM block entails a $O(NBEM^{2})$ storage requirement and a $O(NBEM^{3})$ contribution to the solution time via usual direct solvers. To overcome these pitfalls, the BEM contribution is formulated using the fast multipole method (FMM) and the coupled equations are solved by means of an iterative GMRES solver. Both the storage requirements and the solution times are found to be close to O(NBEM). A preconditioner based on the sparse approximate inverse of the BEM block is shown to improve the convergence of the GMRES solver. Numerical examples involving NBEM = O(10^5 − 10^6) unknowns, run on a PC computer, are presented; they include the Eshelby inclusion (as a validation example), a many-inclusion configuration, and a dam structure. (10.1016/j.compstruc.2004.09.007)
  DOI : 10.1016/j.compstruc.2004.09.007
• Numerical approach in thermomechanical fatigue
  
  • Charkaluk Eric
  • Constantinescu Andrei
  • Thomas Jean-Jacques
  , 2005. This paper presents a global approach of thermomechanical design in the automotive industry based on four different aspects: the loading definition, the modelling of the constitutive law and of the damage and a failure criterion. This approach is applied on cylinder heads and on exhaust manifolds submitted to transient thermal loading and permits to predict the cracked area as well as the lifetime. The main hypothesis and the different aspects are detailed and results on automotive parts are presented.
• 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.
• 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
• 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.
• Mechanics and Materials: some aspects and trends of current research
  
  • Zaoui A.
  , 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.
• 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.
• 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
• 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
• 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
• 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.