Letteratura scientifica selezionata sul tema "Volumes élémentaires représentatifs"
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Articoli di riviste sul tema "Volumes élémentaires représentatifs"
Herrmann, H. J., V. Komiwes, P. Mege e Y. Meimon. "Sur le volume élémentaire représentatif de la loi de perte de charge d'Ergun". Oil & Gas Science and Technology 54, n. 5 (settembre 1999): 577–85. http://dx.doi.org/10.2516/ogst:1999049.
Testo completoFauchille, Anne-Laure, Bram van den Eijnden, Kevin Taylor e Peter David Lee. "Détermination de la taille et du nombre d’échantillons devant être analysés en laboratoire pour la caractérisation statistique de la microstructure d’une roche argileuse". Revue Française de Géotechnique, n. 165 (2020): 1. http://dx.doi.org/10.1051/geotech/2020024.
Testo completoTesi sul tema "Volumes élémentaires représentatifs"
Hitti, Karim. "Simulation numérique de Volumes Élémentaires Représentatifs (VERs) complexes : Génération, Résolution et Homogénéisation". Phd thesis, École Nationale Supérieure des Mines de Paris, 2011. http://pastel.archives-ouvertes.fr/pastel-00667428.
Testo completoTran, Quang Vu. "Locally heterogeneous three-dimensional fibrous media : Representative elementary volumes and calculation of acoustic properties". Electronic Thesis or Diss., Université Gustave Eiffel, 2023. http://www.theses.fr/2023UEFL2081.
Testo completoThis thesis explores the complex relationship between the structures, acoustic properties, and manufacturing processes of non-woven fiber materials. Two families of composite fibrous media, derived from recycled textile fibers and recycled PET fibers, were studied, offering a diversity of polydispersity. Through microstructural characterization and numerical homogenization, this research identified key parameters associated with transport and sound absorption properties.The volume-weighted mean diameter Dv and inverse volume weighted mean diameter Div were found to be essential geometric descriptors. They explain acoustic behaviors at different frequencies, revealing that viscous and thermal exchanges occur through the widest channels of the microstructure at low frequencies; while at high frequencies, the acoustic signature is influenced by the entire microstructure, including the smallest constrictions.The original contributions of this research include (1) the development of Representative Elementary Volumes (REVs) for polydisperse fibrous media; (2) solving an optimization problem based on the degree of polydispersity; (3) and proposing an experimental technique to estimate transport properties at high frequencies.In summary, this thesis offers promising perspectives for understanding and optimizing the acoustic properties of polydisperse fibrous media while identifying crucial microstructural descriptors for these complex materials
Kanit, Toufik. "Notion de volume élémentaire représentatif : approche numérique et statistique pour les microstructure [sic] aléatoires". Paris, ENMP, 2003. http://www.theses.fr/2003ENMP1132.
Testo completoLachihab, Adel. "Un modèle numérique pour les composites biphasés matrice-inclusions rigides: Application à la détermination des propriétés élastiques et en fatigue des enrobés bitumineux". Phd thesis, Ecole des Ponts ParisTech, 2004. http://pastel.archives-ouvertes.fr/pastel-00001036.
Testo completoWu, Qier. "Isothermes de désorption de matériaux cimentaires : étude d'un protocole accéléré et estimation du VER". Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10149/document.
Testo completoIn the framework of French radioactive waste management and storage, the durability evaluation and prediction of concrete structures requires the knowledge of desorption isotherm of concrete. The aim of the present study is to develop an accelerated experimental method to obtain desorption isotherm of cementitious materials more quickly and to estimate the Representative Volume Element (RVE) size related to the desorption isotherm of concrete. In order to ensure that experimental results can be statistically considered representative, a great amount of sliced samples of cementitious materials with three different thicknesses (1 mm, 2 mm and 3 mm) have been de-saturated. The effect of slice thickness and the saturation condition on the mass variation kinetics and the desorption isotherms is analyzed. The influence of the aggregate distribution on the water content and the water saturation degree is also analyzed. A method based on statistical analysis of water content and water saturation degree is proposed to estimate the RVE for water desorption experiment of concrete. The evolution of shrinkage with relative humidity is also followed for each material during the water desorption experiment. A protocol of cycle of rapid desaturation-resaturation is applied and shows the existence of hysteresis between desorption and adsorption
Khdir, Younis Khalid. "Non-linear numerical homogenization : application to elasto-plastic materials". Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10023/document.
Testo completoThis PhD dissertation deals with the numerical homogenization of heterogeneous elastic-plastic random media via large volume computations. The dissertation is presented in two main parts. The first part is dedicated to the effective elastic-plastic response of random two-phase composites stretched under uniaxial loading. The second part is focused on the effective yield response of random porous media over a wide range of stress triaxialities. In the first part, we describe a computational homogenization methodology to estimate the effective elastic-plastic response of random two-phase composite media. The method is based on finite element simulations using three-dimensional cubic cells of different size but smaller than the deterministic representative volume element of the microstructure. In the second part, we describe using the finite element method a computational homogenization study of three-dimensional cubic cells in order to estimate the effective yield surface of random porous media containing one or two populations of voids. The representativity of the overall yield surface estimates is examined using cubic cells containing randomly distributed and oriented spheroidal voids. The computational results are compared with some existing Gurson-type yield criteria
El, Moumen Ahmed. "Prévision du comportement des matériaux hétérogènes basée sur l’homogénéisation numérique : modélisation, visualisation et étude morphologique". Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10077/document.
Testo completoThe homogenization is a technique of Micro-Macro passage taking into account the influence of morphological, mechanical and statistical parameters of the representative microstructure of an heterogeneous material. Numerical modeling has contributed significantly to the development of this technique to determine the physical and mechanical properties of bi-and multi-phase heterogenous materials. The main objective of this work is the prediction of the macroscopic elastic and thermal behaviors of heterogeneous materials. The mechanical and thermal behaviors was determined numerically and compared with experimental and analytical results. The variation of the representative volume element (RVE) versus volume fraction and the contrast was analyzed. This study showed the importance of a rigorous determination of the optimal RVE size. Indeed, it must take into account several parameters such as : volume fraction, contrast, type of property and the morphology of the heterogeneity. A new concept of the equivalent morphology was proposed. This concept introduces the equivalence of the elastic and thermal characteristics of a microstructure of heterogeneous materials with complex morphology and those of a microstructure containing spherical particles. This work led us to developement of a comprehensive approach to microstructural design by integrating the real morphology of heterogeneous microstructure phases incorporating at the same time the image visualization, the morphological study and the geometric and numerical modeling
Rozanski, Adrian. "Sur la représentativité, la taille minimale du VER et les propriétés effectives de transport des matériaux composites aléatoires". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10137/document.
Testo completoThe thesis focuses on random composites and some specific features such as: the minimum size of a representative volume element (RVE) and the determination of effective transport properties. The main objective is to formulate a computationally efficient method which would allow for quick determination of effective properties. The effective properties of transport are considered. It is shown that this class of properties can be estimated either by performing calculations over one large sample or by averaging over a sufficient number of smaller microstructure realizations. However, for a given type of microstructure; the size of such smaller realizations can not be smaller than some critical minimum size. It is shown that this critical size of RVE is strongly affected by several parameters. These are: microstructure type, volume fractions of constituents, contrast in mechanical properties of composite phases, number of performed realizations as well as a desired accuracy. Furthermore, two separate types of representativity are introduced: geometrical representativity and representativity with respect to overall transport properties. Therefore, two distinct criteria for the minimum size of RVE are formulated based on the properties of the two-point correlation function. Comparing to other methods proposed in wide literature, the criterion formulated in the thesis gives an advantage: the condition proposed includes microstructure morphology. Therefore, in order to determine the minimum size of RVE none numerical calculations like those of FE are necessary. A validation of proposed methodology is performed on several examples of 2D microstructures
Wali, Abderrahmen. "Analyse expérimentale et modélisation multi-échelle du comportement mécanique de mélanges Polycarbonate/Polypropylène : effet de la morphologie". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10077.
Testo completoThe objective of this work is to perform experimental characterization and to model the mechanical behaviour of immiscible PC/PP blends. A predominantly spherical microstructure, in the most PC / PP blends, reveals low adhesion due to high interfacial tension between two phases which was observed under a scanning electron microscope (SEM). This results in a negative deviation of the mechanical tensile properties accordingly to the % of PP. One of the possible solutions is to add a third component that can improve adhesion between two phases. In this work PP-g-MA was chosen. Despite its low rigidity and brittleness, it has partially improved the mechanical properties of the blends. A multi-scale approach was applied to model the homogenised behaviour of the PC / PP blends using two different types of models. The first one is based on analytical homogenization and the second one will be defined in the context of numerical homogenization. The statistical distribution law for the size of the dispersed phase was determined from the SEM images. This law was applied for representative volume element (RVE) generation. The behaviour of the constituents has been defined as elastoplastic. Initially assumed hypothesis of a perfect interface did not describe the mechanical behaviour of the blends in a satisfactory manner. In order to improve this, a model introducing cohesive surfaces to simulate interfacial damage is developed using traction-separation law. The model is in good agreement with the experimental results. Finally, parametric study was carried out to highlight the effect of the shape, the number and the orientation of dispersed phase on the nonlinear response of blends
Farhat, Faten. "Modélisation multiéchelle du comportement mécanique des gaz shales". Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1I015/document.
Testo completoThe main objective of this thesis is to study the influence of microstructure on the macroscopic mechanical behavior of heterogeneous rocks, particularly Vaca Muerta shale rock. In this context, micromechanical models are developed by well-adapted homogenization techniques. The microstructure of this rock has been extensively studied in order to define the representative elementary volume indispensable for the implementation of a micromechanical approach. The studied material is modeled as a heterogeneous medium, made up, at mesoscale, of a composite matrix in which are dipped different types of inclusions. On a smaller scale, fine grains of calcite and kerogen are immersed in a porous clay matrix. The homogenization of non-linear instantaneous behavior is established in the context of clay matrix elastoplasticity and the progressive debonding of mineral inclusions: the nano-micro transition leads to the strength domain of the porous clay phase where the solid phase is considered to be a cohesive-frictional material that obeys to the classic Drucker-Prager criterion. Hill’s incremental method is used as a homogenization means at micro-meso and meso-macro transitions. Next, the long-term behavior of the studied material is defined in terms of microstructure degradation. Finally, a simplified micomechanical model is developed to study long-term behavior of clayey and shale rocks in the context of clay matrix viscoplasticity. Based on this model, for the industrial application of the thesis, we study the interaction between Vaca Muerta shale rock and spherical grains of proppants
Capitoli di libri sul tema "Volumes élémentaires représentatifs"
LU, Xiaoxin, Julien YVONNET, Fabrice DETREZ e Jinbo BAI. "Modélisation électromécanique non linéaire multi-échelle de nanocomposites graphène-polymère". In Nanocomposites, 167–98. ISTE Group, 2021. http://dx.doi.org/10.51926/iste.9031.ch6.
Testo completo