Publications

2012

• Stick-slip waves between elastic and rigid half-spaces
  
  • Bui Huy Duong
  • Oueslati Abdelbacet
  Journal of Applied Mathematics and Mechanics, Elsevier, 2012, 76 (5), pp.pages 611-620. The construction of an analytic solution of the problem of stick-slip waves crossing the interface between an elastic half-space and a tigid one under unilateral contact and Coulomb friction is considered. The method of solution is based on the analytic continuation method of Radok's complex potentials within the framework of steady elastodynamic problems. The governing equations combined with the boundary conditions are reduced to a Riemann-Hilbert problem with discontinuous coefficient, and closed-form expressions of the solution are derived. It is found that the existence of solutions depends on the additional velocity, which is related to the longitudinal elongation. If this velocity is ignored, there is no solution, if not, it is possible to construct weakly singular solutions satisfying all stick-slip conditions except over a narrow zone where the waves exhibit a crack-like behaviour. (10.1016/j.jappmathmech.2012.11.003)
  DOI : 10.1016/j.jappmathmech.2012.11.003
• Boiling Crisis as a Critical Phenomenon
  
  • Lloveras Pol
  • Salvat-Pujol Frederick
  • Truskinovsky Lev
  • Vives Eduard
  Physical Review Letters, American Physical Society, 2012, pp.215701. We present the first experimental study of intermittency and avalanche distribution during a boiling crisis. To understand the emergence of power law statistics we propose a simple spin model capturing the measured critical exponent. The model suggests that behind the critical heat flux is a percolation phenomenon involving drying-rewetting competition close to the hot surface. (10.1103/PhysRevLett.108.215701)
  DOI : 10.1103/PhysRevLett.108.215701
• Apparent and effective mechanical properties of linear matrix-inclusion random composites: Improved bounds for the effective behavior
  
  • Salmi Moncef
  • Auslender François
  • Bornert Michel
  • Fogli Michel
  International Journal of Solids and Structures, Elsevier, 2012, 49 (10), pp.1195-1211. This paper is devoted to the derivation of improved bounds for the effective behavior of linear elastic matrix-inclusion composites based on a strategy which is inspired by both the works of Huet (1990) and Danielsson et al. (2007). As shown by the former author, the effective properties of random linear composites can be bounded by ensemble averages of their apparent elastic moduli defined on square (or cubic) volume elements (VEs) and computed with either affine displacement Boundary Conditions (BC) or uniform traction BC. However, in the case of a large contrast of the constituents, the discrepancy between the upper and lower bounds remains significant, even for large values of the VE size. This occurs because the contribution to the total potential (or complementary) energy of the particles (or pores) which intersect the edges of the VE becomes unphysically very large when uniform BC are directly applied to the particles. To avoid such limitations, we considerer non-square (or non-cubic) VEs consisting in simply connex assemblages of cells, each cell being composed of an inclusion surrounded by the matrix, thus forbidding any direct application of BC to the particles. Such VEs are generated by extending the scheme proposed by Danielsson et al. (2007) in the context of periodic random microstructures to fully random microstructures. By applying the classical energy bounding theorems to the non-square VEs, new bounds for the effective behavior are derived. Their application to a two-phase composite composed of an isotropic matrix and aligned identical fibers randomly distributed in the transverse plane leads to sharper bounds which converge quickly with the VE size, even for infinite contrasts. © 2012 Elsevier Ltd. All rights reserved. (10.1016/j.ijsolstr.2012.01.018)
  DOI : 10.1016/j.ijsolstr.2012.01.018
• An adaptive algorithm for cohesive zone model and arbitrary crack propagation
  
  • Chiaruttini Vincent
  • Geoffroy Dominique
  • Riolo Vincent
  • Bonnet Marc
  Revue Européenne de Mécanique Numérique/European Journal of Computational Mechanics, Hermès / Paris : Lavoisier, 2012, 21, pp.208-218. This paper presents an approach to the numerical simulation of crack propagation with cohesive models for the case of structures subjected to mixed mode loadings. The evolution of the crack path is followed by using an adaptive method: with the help of a macroscopic branching criterion based on the calculation of an energetic integral, the evolving crack path is remeshed as the crack evolves in the simulation. Special attention is paid to the unknown fields transfer approach that is crucial for the success of the computational treatment. This approach has been implemented in the finite element code Z-Set (jointly developed by Onera and Ecole des Mines) and is tested on two examples, one featuring a straight crack path and the other involving a complex crack propagation under critical monotonous loading monotonous. (10.1080/17797179.2012.744544)
  DOI : 10.1080/17797179.2012.744544
• Solving dynamic contact problems with local refinement in space and time
  
  • Hager Corinna I
  • Hauret Patrice
  • Le Tallec Patrick
  • Wohlmuth Barbara I
  Computer Methods in Applied Mechanics and Engineering, Elsevier, 2012, 201, pp.25 - 41. Frictional dynamic contact problems with complex geometries are a challenging task from the compu tational as well as from the analytical point of view since they generally involve space and time multi scale aspects. To be able to reduce the complexity of this kind of contact problem, we employ a non conforming domain decomposition method in space, consisting of a coarse global mesh not resolving the local struc ture and an overlapping fine patch for the contact computation. This leads to several benefits: First, we resolve the details of the surface only where it is needed, i.e., in the vicinity of the actual contact zone. Second, the subproblems can be discretized independently of each other which enables us to choose a much finer time scale on the contact zone than on the coarse domain. Here, we propose a set of interface conditions that yield optimal a priori error estimates on the fine meshed subdomain without any artificial dissipation. Further, we develop an efficient iterative solution scheme for the coupled problem that is robust with respect to jumps in the material parameters. Several complex numerical examples illustrate the performance of the new scheme. (10.1016/j.cma.2011.09.006)
  DOI : 10.1016/j.cma.2011.09.006
• Plasticity of Formable All-metal Sandwich Sheets: Virtual Experiments and Constitutive Modeling
  
  • Besse C.
  • Mohr Dirk
  International Journal of Solids and Structures, Elsevier, 2012, 49 (19-20), pp.2863-2880. The mechanical behavior of a metallic sandwich sheet material composed of two flat face sheets and two bi-directionally corrugated core layers is analyzed in detail. The manufacturing of the sandwich material is simulated to obtain a detailed unit cell model which accounts for the non-uniform thickness distribution and residual stresses associated with the stamping of the core layers. Virtual experiments are performed by subjecting the unit cell model to various combinations of bi-axial in-plane loading including the special cases of uniaxial tension, uniaxial compression, equi-biaxial tension and shear. The results demonstrate that the core structure's contribution to the in-plane load carrying capacity of the sandwich sheet material is similar to that of the face sheets. The numerical results are also used to identify the effective yield surface and hardening response of both the core layer and the face sheets. An anisotropic yield function with linear pressure dependency is proposed to approximate the equal-plastic work surfaces for the core structure and face sheets. Furthermore, a new two-surface model with non-linear interpolation based on plastic work density is presented to describe the observed combined isotropic-distortional hardening of the core structure (10.1016/j.ijsolstr.2012.04.032)
  DOI : 10.1016/j.ijsolstr.2012.04.032
• Anisotropic Plasticity Model Coupled with Lode Angle Dependent Strain-Induced Transformation Kinetics Law
  
  • Beese A.M.
  • Mohr Dirk
  Journal of the Mechanics and Physics of Solids, Elsevier, 2012, pp.1922-1940.
• Nonlinear dynamics of a rotating shaft with a breathing crack
  
  • El Arem Saber
  • Nguyen Quoc Son
  Annals of Solid and Structural Mechanics, Springer Berlin Heidelberg, 2012, 3, pp.1-14. In this paper, the effects of a breathing crack on the vibratory characteristics of a rotating shaft are investigated. A new, simple and robust model composed of two rigid bars connected with a nonlinear flexural spring is proposed. The nonlinear spring, located at the cracked transverse section position, concentrates the global stiffness of the cracked shaft. The breathing mechanism of the crack is described by a more realistic periodic variation of the global stiffness depending not only but substantially on the system vibratory response. It is based on an energy formulation of the problem of 3D elasticity with unilateral contact conditions on the crack lips. A possible partial opening and closing of the crack is considered which makes the approach more appropriate for deep cracks modeling. The harmonic balance method, direct time-integration schemes and nonlinear dynamics tools are used to characterize the global dynamics of the system. The effects of the crack depth and rotating frequency have been meticulously examined and it was found that the cracked shaft never exhibits chaotic or quasi-periodic vibratory response. (10.1007/s12356-011-0025-5)
  DOI : 10.1007/s12356-011-0025-5
• Mechanical Behavior of Salt VII
  
  • Berest Pierre
  • Mehdi Ghoreychi
  • Hadj Hassen Faouzi
  • Michel Tijani
  , 2012, pp.492.
• Infrared thermovision of damage in brittle geomaterials
  
  • Luong Minh-Phong
  • Emami Tabrizi Mehrdad
  • Eytard Jean-Christophe
  • Maiolino Siegfried
  , 2012, pp.1-6. This paper aims to illustrate the use of infrared thermography as a non-destructive and non-contact technique to observe the phenomenological manifestation of damage in brittle geomaterials under unconfined compression. It allows records and observations in real time of heat patterns produced by the dissipation of energy generated by plasticity. The experimental results show that this technique, which couples mechanical and thermal energy, can be used for illustrating the onset of damage mechanism by stress concentration in weakness zones.
• Modèles, systèmes d'information et gestion viable De l'environnement (MOTIVE) d'IRSTEA
  
  • Rapaport Alain
  • Auger Pierre
  • Gensel Jérôme
  • Labiod Houda
  • Sebag Michèle
  , 2012.
• Full field investigation of salt deformation at room temperature: cooperation of crystal plasticity and grain sliding
  
  • Bourcier Mathieu
  • Dimanov Alexandre
  • Héripré Eva
  • Raphanel Jean
  • Bornert Michel
  • Desbois Guillaume
  , 2012. We observed with optical and scanning electron microscopy halite samples during uniaxial compression. Surface displacement fields were retrieved from digital images taken at different loading stages thanks to digital image correlation (DIC) techniques, on the basis of which we could 1) compute global and local strain fields, 2) identify two co-operational deformation mechanisms. The latter were 1) crystal slip plasticity (CSP), as evidenced by the occurrence of slip lines and computed discrete intracrystalline slip bands at the grain surfaces, 2) interfacial micro-cracking and grain boundary sliding (GBS), as evidenced by the computed relative interfacial displacements. The heterogeneities of the strain fields at the aggregate and at the grain scale, and the local contributions of each mechanism were clearly related to the microstructure, i.e. the relative crystallographic orientations of neighboring grains and the interfacial orientations with respect to the principal stress.
• Perfectly Matched Layer with Mixed Spectral Elements for the Propagation of Linearized Water Waves
  
  • Cohen Gary
  • Imperiale Sébastien
  Communications in Computational Physics, Global Science Press, 2012, 11 (2), pp.285-302. After setting a mixed formulation for the propagation of linearized water waves problem, we define its spectral element approximation. Then, in order to take into account unbounded domains, we construct absorbing perfectly matched layer for the problem. We approximate these perfectly matched layer by mixed spectral elements and show their stability using the 'frozen coefficient' technique. Finally, numerical results will prove the efficiency of the perfectly matched layer compared to classical absorbing boundary conditions. (10.4208/cicp.201109.261110s)
  DOI : 10.4208/cicp.201109.261110s
• Error estimates for 1D asymptotic models in coaxial cables with non-homogeneous cross-section
  
  • Imperiale Sébastien
  • Joly Patrick
  Advances in Applied Mechanics, New York ; London ; Paris [etc] : Academic Press, 2012, xx. This paper is the first contribution towards the rigorous justification of asymptotic 1D models for the time-domain simulation of the propagation of electromagnetic waves in coaxial cables. Our general objective is to derive error estimates between the "exact" solution of the full 3D model and the "approximate" solution of the 1D model known as the Telegraphist's equation. (10.4208/aamm.12-12S06)
  DOI : 10.4208/aamm.12-12S06
• Experiments and Modeling of Iron-Particle-Filled Magnetorheological Elastomers
  
  • Danas Kostas
  • Kankanala Sunny
  • Triantafyllidis Nicolas
  Journal of the Mechanics and Physics of Solids, Elsevier, 2012, 60, pp.120 - 138.
• Experiments and Modeling of Anisotropic Aluminum Extrusions under Multi-axial Loading - Part I: Plasticity
  
  • Dunand M.
  • Maertens A.
  • Luo Meng
  • Mohr Dirk
  International Journal of Plasticity, Elsevier, 2012, pp.34-49.
• From Discrete Visco-Elasticity to Continuum Rate-Independent Plasticity: Rigorous Results
  
  • Mielke A.
  • Truskinovsky Lev
  Archive for Rational Mechanics and Analysis, Springer Verlag, 2012, 203, pp.577-619. We show that continuum models for ideal plasticity can be obtained as a rigorous mathematical limit starting from a discrete microscopic model describing a visco-elastic crystal lattice with quenched disorder. The constitutive structure changes as a result of two concurrent limiting procedures: the vanishing-viscosity limit and the discrete-to-continuum limit. In the course of these limits a non-convex elastic problem transforms into a convex elastic problem while the quadratic rate-dependent dissipation of visco-elastic lattice transforms into a singular rate-independent dissipation of an ideally plastic solid. In order to emphasize our ideas we employ in our proofs the simplest prototypical system mimicking the phenomenology of transformational plasticity in shape-memory alloys. The approach, however, is sufficiently general that it can be used for similar reductions in the cases of more general plasticity and damage models. (10.1007/s00205-011-0460-9)
  DOI : 10.1007/s00205-011-0460-9
• Reciprocity gap method
  
  • Andrieux Stéphane
  • Bui Hui Duong
  • Constantinescu Andrei
  , 2012, pp.368-378. (10.1002/9781118578469.ch13)
  DOI : 10.1002/9781118578469.ch13
• Cyclic behaviour of structures under thermomechanical loadings: Application to exhaust manifolds
  
  • Benoit À La Guillaume Aurélie
  • Maitournam Habibou
  • Rémy Luc
  • Oger F.
  International Journal of Fatigue, Elsevier, 2012, 38, pp.65-74. A structure subjected to thermomechanical cyclic loadings may exhibit various cyclic behaviours: perfect elasticity, elastic shakedown, plastic shakedown and ratchetting. The quantitative characterization of these different asymptotic states is addressed in this paper, in the context of the Generalized Standard Materials (GSM). Criteria are established to identify them and capture the trend line of their evolution, in the context of numerical simulation. The definitions are extended to the case of temperature dependent mechanical properties. Simple strain paths are first considered to illustrate the relevancy of the proposition. Finally, as an application, the example of an exhaust manifold subjected to a classical thermomechanical fatigue test is analyzed. (10.1016/j.ijfatigue.2011.11.012)
  DOI : 10.1016/j.ijfatigue.2011.11.012
• Macroscopic plasticity modeling of anisotropic aluminum extrusions using a Reduced Texture Methodology
  
  • Rousselier Gilles
  • Luo Meng
  • Mohr Dirk
  International Journal of Plasticity, Elsevier, 2012, 30-31, pp.144-165. This paper deals with the modeling of the plasticity of extruded aluminum 6260-T6 at the macroscopic level. The model is based on the framework of classical polycrystalline plasticity. A Reduced Texture Methodology (RTM) is used to provide the computational efficiency needed for industrial applications. The RTM approach involves a significant reduction of the number of representative crystallographic orientations. Furthermore, a special hybrid experimental-numerical procedure is used to identify all model parameters (including texture) from mechanical experiments. The experimental program includes uniaxial tensile experiments for different material orientations. Due to the heterogeneity in texture and grain size along the thickness direction of the 2 mm thick extruded material, specimens of full- and reduced thickness are prepared. Uniaxial compression-tension experiments are completed with the help of an anti-buckling device. The mechanical response of full-thickness specimens is modeled using 12 crystallographic orientations. Only eight distinct grain orientations are required to obtain satisfactory predictions for the reduced-thickness specimens with the same set of hardening parameters. The models describe well the stress-strain curves and Lankford ratios for all directions. It is found that the computed reduced textures are in good agreement with EBSD measurements. The 8-grain model is also validated for non-proportional loading paths in the space of tension and shear. Simulations of punch experiments are performed to further validate the model and to demonstrate the computational efficiency of the RTM based polycrystalline plasticity model in structural applications. (10.1016/j.ijplas.2011.10.004)
  DOI : 10.1016/j.ijplas.2011.10.004
• Audio, visual, and audio-visual egocentric distance perception by moving participants in virtual environments
  
  • Rébillat Marc
  • Boutillon Xavier
  • Corteel Étienne
  • Katz Brian F. G.
  ACM Transactions on Applied Perception, Association for Computing Machinery, 2012, 9 (4), pp.19 (p. 1-17). A study on audio, visual, and audio-visual egocentric distance perception by moving participants in virtual environments is presented. Audio-visual rendering is provided using tracked passive visual stereoscopy and acoustic wave fi eld synthesis (WFS). Distances are estimated using indirect blind-walking (triangulation) under each rendering condition. Experimental results show that distances perceived in the virtual environment are accurately estimated or overestimated for rendered distances closer than the position of the audio-visual rendering system and underestimated for distances farther. Interestingly, participants perceived each virtual object at a modality-independent distance when using the audio modality, the visual modality, or the combination of both. Results show WFS capable of synthesizing perceptually meaningful sound fields in terms of distance. Dynamic audio-visual cues were used by participants when estimating the distances in the virtual world. Moving may have provided participants with a better visual distance perception of close distances than if they were static. No correlation between the feeling of presence and the visual distance underestimation has been found. To explain the observed perceptual distance compression, it is proposed that, due to con flicting distance cues, the audio-visual rendering system physically anchors the virtual world to the real world. Virtual objects are thus attracted by the physical audio-visual rendering system. (10.1145/2355598.2355602)
  DOI : 10.1145/2355598.2355602
• An energy-preserving muscle tissue model: formulation and compatible discretizations
  
  • Chapelle Dominique
  • Le Tallec Patrick
  • Moireau Philippe
  • Sorine Michel
  International Journal for Multiscale Computational Engineering, Begell House, 2012, 10 (2), pp.189-211. In this paper we propose a muscle tissue model -- valid for striated muscles in general, and for the myocardium in particular -- based on a multi-scale physiological description. This model extends and refines an earlier-proposed formulation by allowing to account for all major energy exchanges and balances, from the chemical activity coupled with oxygen supply to the production of actual mechanical work, namely, the biological function of the tissue. We thus perform a thorough analysis of the energy mechanisms prevailing at the various scales, and we proceed to propose a complete discretization strategy -- in time and space -- respecting the same balance laws. This will be crucial in future works to adequately model the many important physiological -- normal and pathological -- phenomena associated with these energy considerations. (10.1615/IntJMultCompEng.2011002360)
  DOI : 10.1615/IntJMultCompEng.2011002360
• Application of the multi-level time-harmonic fast multipole BEM to 3-D visco-elastodynamics
  
  • Grasso Eva
  • Chaillat Stéphanie
  • Bonnet Marc
  • Semblat Jean-François
  Engineering Analysis with Boundary Elements, Elsevier, 2012, 36, pp.744-758. This article extends previous work by the authors on the single- and multi-domain time-harmonic elastodynamic multi-level fast multipole BEM formulations to the case of weakly dissipative viscoelastic media. The underlying boundary integral equation and fast multipole formulations are formally identical to that of elastodynamics, except that the wavenumbers are complex-valued due to attenuation. Attention is focused on evaluating the multipole decomposition of the viscoelastodynamic fundamental solution. A damping-dependent modification of the selection rule for the multipole truncation parameter, required by the presence of complex wavenumbers, is proposed. It is empirically adjusted so as to maintain a constant accuracy over the damping range of interest in the approximation of the fundamental solution, and validated on numerical tests focusing on the evaluation of the latter. The proposed modification is then assessed on 3D single-region and multi-region visco-elastodynamic examples for which exact solutions are known. Finally, the multi-region formulation is applied to the problem of a wave propagating in a semi-infinite medium with a lossy semi-spherical inclusion (seismic wave in alluvial basin). These examples involve problem sizes of up to about $3\,10^{5}$ boundary unknowns. (10.1016/j.enganabound.2011.11.015)
  DOI : 10.1016/j.enganabound.2011.11.015
• Modelling radiation effects on the fracture process in simplified nuclear glass.
  
  • Kieu Le-Hai
  • Delaye Jean-Marc
  • Stolz Claude
  Key Engineering Materials, Trans Tech Publications, 2012, 488-489, pp.154-157.
• Experiments and Modeling of Anisotropic Aluminum Extrusions under Multi-axial Loading - Part II: Fracture
  
  • Dunand M.
  • Luo Meng
  • Mohr Dirk
  International Journal of Plasticity, Elsevier, 2012, pp.36-58.