Publications

2003

• Testing with SHPB from quasi-static to dynamic strain rates
  
  • Ohtman R.
  • Bussac M. N.
  • Collet P.
  • Gary G.
  Journal de Physique IV Proceedings, EDP Sciences, 2003, 110, pp.397-404. We have developed a new method for separating dispersive waves in elastic and viscoelastic rods from three-point strain and one-point velocity measurements. Stress, strain, displacement and velocity, which were supposed to be homogenous in a rod section, were therefore determined at any point ofthe bar. This method is based on the assumption of a one dimensional and single mode dispersive wave propagation. This method was used in the frequency domain and took into account wave dispersion. It was shown to be stable with respect to noise. The measuring time is increased considerably. Subsequently, the maximum strain which can be measured in a material tested with a classical SHPB (Split Hopkinson Pressure Bar) set-up is also increased and is no more limited by the length of the bars. The method was used to evaluate the rate sensitivity ofaluminum honeycomb over a wide range ofstrain-rates (from 10 -2 to 1000 s -1). (10.1051/jp4:20020726)
  DOI : 10.1051/jp4:20020726
• Bearing capacity of strip footings with horizontal confinement
  
  • Salençon Jean
  Comptes rendus de l’Académie des sciences. Série IIb, Mécanique, Elsevier, 2003, 331, pp.319-324. For a strip footing under axial loading, the bearing capacity is influenced by the presence of rigid walls confining the foundation soil. This problem is investigated within the framework of the theory of yield design, considering both a perfectly rough and a frictionless contact condition at the interfaces with the walls in the case of a purely cohesive soil. Upper bounds for the correction factor to be applied to the classical value of the bearing capacity are determined, as functions of the non-dimensional geometric parameter of the problem, through the kinematic approach, implementing virtual velocity fields inspired from the solution to the problem of inverted extrusion. In the perfectly rough case, it appears that the new upper bound is a significant improvement of those already available. A very simple relationship is established, which derives the upper bound for the frictionless walls from the upper bound for the rough walls. A general conclusion of the analysis is that, for the values of the geometric parameter that are likely to be encountered in practice, the increase in the bearing capacity due to the presence of the rigid walls remains very small. (10.1016/S1631-0721(03)00071-8)
  DOI : 10.1016/S1631-0721(03)00071-8
• Creep of polycrystalline anorthite and diopside
  
  • Dimanov Alexandre
  • Lavie Marie-Pierre
  • Ingrin Jannick
  • Dresen Georg
  • Jaoul Olivier
  Journal of Geophysical Research : Solid Earth, American Geophysical Union, 2003, 108 (B1), pp.doi:10.10292002JB001815. (10.1029/2002JB001815)
  DOI : 10.1029/2002JB001815
• Génie parasismique : aspects dynamiques et vibratoires en génie civil
  
  • Luong Minh-Phong
  , 2003, pp.3 tomes. Actes du colloque AFPS 2003. Plus de 160 communications ont été présentées, réparties selon les thèmes suivants : - Géosciences (vol. 1) : sismologie générale et aléa déterministe ; mouvements sismiques pour l'ingénieur ; effets de site classiques ; interaction sol-structure et effet de site "urbains" ; géotechnique parasismique (sols, fondations et ouvrages). - Dynamique des structures et conception (vol. 2) : méthodes d'analyse et de modélisation (analyse simplifiée et indicateurs de nocivité, méthodes spécifiques) ; expérimentation ; constructions métalliques ; équipements industriels et structures particulières ; ponts. - Gestion de l'existant et du risque (vol. 3) : diagnostic et renforcement de l'existant ; existant nucléaire ; méthode d'estimation de la vulnérabilité à grande échelle ; scénarios et vulnérabilité urbaine ; aspects socio-économiques ; vers un nouveau zonage sismique de la France. - Benchmark Camus (vol. 3).
• Linear stability analysis in fluid-structure interaction with transpiration. Part II: Numerical analysis and applications
  
  • Fernández Miguel Angel
  • Le Tallec Patrick
  Computer Methods in Applied Mechanics and Engineering, Elsevier, 2003, 192 (43), pp.4837-4873. This paper constitutes the numerical counterpart of the mathematical framework introduced in Part I. We address the problem of flutter analysis of a coupled fluid-structure system involving an incompressible Newtonian fluid and a reduced structure. We use the Linearization Principle approach developed in Part I, particularly suited for fluid-structure problems involving moving boundaries. Thus, the stability analysis is reduced to the computation of the leftmost eigenvalues of a coupled eigenproblem of minimal complexity. This eigenproblem involves the linearized incompressible Navier-Stokes equations and those of a reduced linear structure. The coupling is realized through specific transpiration interface conditions. The eigenproblem is discretized using a finite element approximation and its smallest real part eigenvalues are computed by combining a generalized Cayley transform and an implicit restarted Arnoldi method. Finally, we report three numerical experiments : a structure immersed in a fluid at rest, a cantilever pipe conveying a fluid flow and a rectangular bridge deck profile under wind effects. The numerical results are compared to former approaches and experimental data. The quality of these numerical results is very satisfactory and promising. (10.1016/j.cma.2003.08.001)
  DOI : 10.1016/j.cma.2003.08.001
• Identification de failles sismiques par une fonctionnelle de réciprocité généralisée
  
  • Bui Huy Duong
  • Constantinescu Andrei
  • Maigre Hubert
  , 2003, 1, pp.13-20.
• Microstructure influence on the damage initiation in unirradiated zirconium alloys
  
  • Elbachiri K.
  • Crépin Jérôme
  • Rebeyrolle V.
  • Bretheau T.
  , 2003. No abstract provided
• Identification de lois de comportement cristallines à partir du couplage EBSD/microextensometrie/Eléments Finis. Application au zirconium grade 702
  
  • Dexet M.
  • Crépin Jérôme
  • Gélébart L.
  , 2003. No abstract provided
• Contribution du fluage à froid et de l'hydrogène à la fissuration anormale du Ti 6246 sous chargement cyclique à fort Kmax
  
  • Doquet V.
  • Mignot F.
  • Sarrazin-Baudoux C.
  , 2003. No abstract provided
• Couplage EBSD - micro-extensométrie et identification de lois cristallines
  
  • Roos A.
  • Hoc T.
  • Gélébart L.
  • Crépin Jérôme
  • Bornert Michel
  • Bretheau T.
  , 2003. No abstract provided
• Thermomechanical properties of polycarbonate under dynamic loading
  
  • Lerch V.
  • Gary G.
  • Hervé P.
  Journal de Physique IV Proceedings, EDP Sciences, 2003, 110, pp.159-164. In the present study, dynamic compression tests have been performed on polycarbonate (PC) specimen for strain rates in the range of 500 to 2000s -1 and on aluminum for a strain rate around 1300s -1 using a Split Hopkinson Pressure Bar (SHPB). Temperature measurement has been carried out using a fast response infrared optical pyrometer which is able to measure the surface temperature rise of a specimen during the tests. The temperature data shows that the mechanical work is not completely converted into heat. It implies the existence of a stored energy within the material and possibly a subsequent delay for the conversion of mechanical work into heat. (10.1051/jp4:20020687)
  DOI : 10.1051/jp4:20020687
• Statistical and Numerical analysis of the nonlinear behaviour of a porous materials with a heterogeneous distribution of pores
  
  • Bilger Nicolas
  • Bornert Michel
  • Auslender François
  • Michel Jean-Claude
  • Moulinec Hervé
  • Suquet Pierre
  • Zaoui André
  , 2003. The yield stress of a ductile 2D porous material with a heterogeneous distribution of pores is investigated by means of a numerical tool based on the Fast Fourier Transform. Random distributions of circular voids, with a uniform or variable pore size and with overlapping or clearly separated pores, are compared, for a same overall porosity, to microstructures obtained as the intersection of the previous ones with a boolean scheme with a larger characteristic size. For pure shear and even more under purely hydrostatic load, the numerical simulations show that the pore distribution has a strong effect on the yield stress, with the so-called “Hashin Composite Cylinders Assemblage” being the hardest microstructure and the connected clusters the softest, while disconnected clusters lead to intermediate responses. An image analysis tool for the statistical characterization of the pore distribution is then proposed. It is based on the distribution function of the distance function, the width of which increases with the presence of clusters. An additional analysis allows one to distinguish microstructures with connected clusters from those with disconnected ones.
• Ondes adhérence-glissement-décollement sous contact unilatéral frottant
  
  • Oueslati Abdelbacet
  • Nguyen Quoc Son
  • Baillet Laurent
  Comptes Rendus. Mécanique, Académie des sciences (Paris), 2003, 331 (2), pp.133-140. Il s'agit d'une étude numérique sur la réponse dynamique d'un système de deux cylindres coaxiaux, en rotation relative avec contact unilatéral frottant suivant la loi de Coulomb. On complète les résultats semi-analytiques antérieurs obtenus dans Moirot, Nguyen, C. R. Acad. Sci. Paris Sér. IIb 328 (2000) 663–669, sur les ondes adhérence–glissement en simulant par le calcul numérique la transition dynamique du système à partir d'un état initial quelconque vers la propagation d'une onde de surface. Le cas des ondes adhérence–glissement–décollement est examiné. (10.1016/S1631-0721(02)00009-8)
  DOI : 10.1016/S1631-0721(02)00009-8
• A computational basis for elastodynamic cavity identification in a semi-infinite solid
  
  • Nintcheu Fata Sylvain
  • Guzina Bojan B
  • Bonnet Marc
  Computational Mechanics, Springer Verlag, 2003, 32, pp.370-380. The focus of this paper is a computational platform for the non-intrusive, active seismic imaging of subterranean openings by means of an elastodynamic boundary integral equation (BIE) method. On simulating the ground response to steady-state seismic excitation as that of a uniform, semi-infinite elastic solid, solution to the 3D inverse scattering problem is contrived as a task of minimizing the misfit between experimental observations and BIE predictions of the surface ground motion. The forward elastodynamic solution revolves around the use of the half-space Greenrsquos functions, which analytically incorporate the traction-free boundary condition at the ground surface and thus allow the discretization and imaging effort to be focused on the surface of a hidden cavity. For a rigorous approach to the gradient-based minimization employed to resolve the cavity, sensitivities of the trial boundary element model with respect to (geometric) void parameters are evaluated using an adjoint field approach. Details of the computational treatment, including the regularized (i.e. Cauchy principal value-free) boundary integral equations for the primary and adjoint problem, the necessary evaluation of surface displacement gradients and their implementation into a parallel code, are highlighted. Through a suite of numerical examples involving the identification of an ellipsoidal cavity, a parametric study is presented which illustrates the importance of several key parameters on the imaging procedure including the prior information, ldquomeasurementrdquo noise, and the amount of experimental input. (10.1007/s00466-003-0494-4)
  DOI : 10.1007/s00466-003-0494-4
• Stability and bifurcation with moving discontinuities
  
  • Stolz Claude
  • Pradeilles-Duval Rachel-Marie
  , 2003, pp.261-268. The propagation of moving surface inside a body is analysed in the framework of thermodynamics, when the moving surface is associated with an irreversible change of mechanical properties. The thermodynamical force associated to the propagation has the form of an energy release rate. Quasistatic rate boundary value problem is given when the propagation of the interface is governed by a normality rule. Extension to generalised media to study delamination is also investigated. (10.1007/0-387-26261-X_26)
  DOI : 10.1007/0-387-26261-X_26
• Modélisation du comportement dynamique d'une courroie de distribution
  
  • Bourgeois M.
  • Thomas J.-J.
  • Stolz Claude
  , 2003, pp.189-196 (tome 2). No abstract provided
• Méthode numérique pour l'identification de cavités enterrées à l'aide de données élastodynamiques
  
  • Bonnet Marc
  • Guzina Bojan B
  • Nintcheu Fata Sylvain
  , 2003, 1, pp.209-216.
• Investigation of hydrogen and creep contributions to the abnormal fatigue cracking of Ti6246 at high Kmax
  
  • Mignot Frédéric
  • Doquet Véronique
  • Sarrazin-Baudoux Christine
  • Petit Jean
  • Raimbault Louis
  , 2003.
• Activation of diffuse discontinuities and folding of sedimentary layers
  
  • Guiton Martin
  • Leroy Yves
  • Sassi William
  Journal of Geophysical Research : Solid Earth, American Geophysical Union, 2003, 108 (B4), pp.1-20. Folding of sedimentary layers is often accommodated by the opening or sliding of inherited and new discontinuities which are assumed here to be diffuse so that a continuum description applies at the fold scale. The rock rheology is then described with an elastoplasticity model for which the permanent deformation is of simple shear (sliding) or dilation (opening) with respect to specific orientations of the new or inherited diffuse discontinuities. To illustrate the relation between folding and activation of diffuse discontinuities, a three-dimensional layer under compression in the two horizontal directions and sustaining the overburden lithostatic pressure is studied. Cylindrical buckling occurs either before (elastic) or after the diffuse discontinuities have been activated. If buckling is elastic, inherited vertical discontinuities, striking obliquely to the fold geometrical axes, are activated in a sliding mode in the outer arc, leading to a rotation of the principal stress directions. Opening is then detected across new vertical planes striking obliquely to the fold axis. The activation of inherited or new vertical discontinuities can be suppressed if sliding takes place along weak bedding interfaces. Alternatively, early and homogeneous layer-parallel shortening, marked by a reverse fault mode, drastically reduces the critical buckling load compared to the Euler load and modifies the final geometry of buckling which is then more of a circular dome shape. The switching in buckling mode results in the fold limbs in a change from the early reverse fault to a strike-slip fault sliding and to opening across diffuse planes oriented consistently with the final circular structure. (10.1029/2002JB001770)
  DOI : 10.1029/2002JB001770
• A study of cellular structures under impact loading
  
  • Abdennadher Salim
  • Zhao Han
  • Othman Ramzi
  , 2003. This paper presents the effect of inertia of cellular structures under impact loading. Experimental results under static and dynamic loading will be presented for square tubes made of a rate quasi-insensitive material (brass), the dynamic results being obtained using modified split Hopkinson pressure bar technique. The numeric simulation under Ls-dyna of those tests giving similar results will be also presented. Presented experimental, numeric results show that the inertia effect is a dominant factor responsible for the enhancement of crushing strength of cellular structures. (10.1051/jp4:20020733)
  DOI : 10.1051/jp4:20020733
• Transmissibilité vibratoire d'un matériau de recyclage
  
  • Luong M. P.
  • Eytard J. C.
  • Khay M.
  • Vinceslas G.
  • Papachristou D.
  , 2003, pp.349-356 (tome 1). No abstract provided
• Simulation of stage I fatigue crack gowth in a polycrystal through coupled FEM and discrete dislocation dynamics
  
  • Bertolino Graciela
  • Doquet Véronique
  • Sauzay Maxime
  , 2003. An attempt to model the variability of short crack development in high-cycle fatigue is made by coupling finite element computations of the stresses ahead of a microcrack in a polycrystal with simulations of crack growth along slip planes based on discrete dislocations dynamics. The model predicts a large scatter in growth rates related to the crystallographic disorientations along the crack path. It also describes qualitatively the influence of the mean grain size and the fact that overloads may suppress the endurance limit by allowing arrested cracks to cross the grain boundaries.
• Explicit kinetic relation from `first principles
  
  • Truskinovsky L.
  • Vainchtein A.
  , 2003.
• Combined experimental and modelling approaches to the micromechanics of polycrystals and composites
  
  • Bornert Michel
  • Crépin Jérôme
  • Zaoui André
  , 2003.
• Mobility of lattice defects: discrete and continuum approaches
  
  • Kresse Olga
  • Truskinovsky Lev
  Journal of the Mechanics and Physics of Solids, Elsevier, 2003, 51, pp.1305-1332. In this paper, we study a highly idealized model of a moving lattice defect allowing for an explicit, “first principles” computation of a functional relation between the macroscopic configurational force and the velocity of the defect. The discrete model is purely conservative and contains information only about elasticities of the constitutive elements. The apparent dissipation is due to the presence of microinstabilities and the nonlinearity-induced tunneling of the energy from long to short wavelengths. This type of “radiative damping” is believed to be generic and accounting for a considerable fraction of inelastic irreversibility associated with fracture, plasticity and phase transitions. The paper contains direct comparison of the exact lattice solution with various continuum and quasicontinuum approximations. Despite its simplicity, the model can be used directly for the description of dynamic phase transitions in thin films. (10.1016/S0022-5096(03)00019-X)
  DOI : 10.1016/S0022-5096(03)00019-X