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Author: Trung Kien Nguyen Publisher: ISBN: Category : Languages : fr Pages : 0
Book Description
Ce travail de recherche présente la modélisation du comportement mécanique des matériaux granulaires cohésifs par une approche multi-échelle en combinant la méthode des éléments finis (FEM) et la méthode des éléments discrets (DEM). A l'échelle microscopique, la DEM est utilisé pour modéliser un assemblage granulaire alors qu'à l'échelle macroscopique, la solution numérique est obtenue par la FEM. Afin de faire un pont entre l'échelle micro et macroscopique, un Volume Elementaire Représentative (VER) est considéré dans lequel la contrainte suite à une déformation imposée résulte d'un calcul numérique de type DEM. Par cette manière, la loi numérique constitutive est déterminé par la modélisation de la microstructure, et par conséquent prenant en compte les natures des matériaux granulaires. Après avoir achevé à construire la loi numérique, on propose d'étudier les propriétés de cette loi incrémentale en terme des enveloppes de réponse Gudehus, et des analyses en bande de cisaillement. Cet étude nous permet d'avoir une vision générale sur cette nouvelle loi. Dans cette contribution numérique multi-échelle, en implémentant la loi numérique DEM dans un code de calcul par éléments finis, un outil numérique est obtenu et utilisé à simuler des essais menés au laboratoire. Des résultats obtenus produisant la localisation de la déformation en bandes de cisaillement seront analysés et discutés.
Author: Trung Kien Nguyen Publisher: ISBN: Category : Languages : fr Pages : 0
Book Description
Ce travail de recherche présente la modélisation du comportement mécanique des matériaux granulaires cohésifs par une approche multi-échelle en combinant la méthode des éléments finis (FEM) et la méthode des éléments discrets (DEM). A l'échelle microscopique, la DEM est utilisé pour modéliser un assemblage granulaire alors qu'à l'échelle macroscopique, la solution numérique est obtenue par la FEM. Afin de faire un pont entre l'échelle micro et macroscopique, un Volume Elementaire Représentative (VER) est considéré dans lequel la contrainte suite à une déformation imposée résulte d'un calcul numérique de type DEM. Par cette manière, la loi numérique constitutive est déterminé par la modélisation de la microstructure, et par conséquent prenant en compte les natures des matériaux granulaires. Après avoir achevé à construire la loi numérique, on propose d'étudier les propriétés de cette loi incrémentale en terme des enveloppes de réponse Gudehus, et des analyses en bande de cisaillement. Cet étude nous permet d'avoir une vision générale sur cette nouvelle loi. Dans cette contribution numérique multi-échelle, en implémentant la loi numérique DEM dans un code de calcul par éléments finis, un outil numérique est obtenu et utilisé à simuler des essais menés au laboratoire. Des résultats obtenus produisant la localisation de la déformation en bandes de cisaillement seront analysés et discutés.
Author: Nicolas Gland Publisher: ISBN: Category : Languages : en Pages : 294
Book Description
The understanding of structural and mechanical properties of granular assemblies remains an open issue. The numerical modelling of granular media, using the Molecular Dynamic approach, brings some answers to critical problems. At first, we are studying the effects of mixture parameters on the degree of order and on the stress distribution in theses arrangements of grains. Next, we are interested in the acoustic properties of these media, which are very nonlinear in comparison to continuous elastic solids; ours simulations serve to clarify the deficiencies of Effective Medium Theory, which only partially account for the dependency of elastic moduli with pressure. We show that relaxation of grains, following an infinitesimal deformation is an essential component of the shear modulus. There is clearly a need for an alternative formulation and the traditional elasto-plastic approach is faced with new theories. If, the numerical simulation led in this study, which measure the response function of granular media (stress field generated by a point force), shows an elastic scaling, it also accounts for important relaxation process. The deformation mechanisms of granular materials were also study by simulating bixial compression tests, which reproduce qualitatively well the classical mechanicals data (stress peak, compaction/dilatancy transition), and also localization of the deformation; while at low pressure, grains rotations accommodate the deformation, at high pressure, the mobilization of friction is more pronounced. Finally, we propose a probabilistic model of damage of granular rocks, which predicts a dependency of damage both with the cementation heterogeneity and with the sample size. These predictions are confirmed by simulations, which also highlight two successive damage behaviours, diffuse at first and then concentrated in clusters.
Author: Mohamed Satee El Hosri Publisher: ISBN: Category : Languages : fr Pages : 203
Book Description
Le module de cisaillement (ou d'Young) et le coefficient d'amortissement sont les paramètres fondamentaux pour étudier le comportement du sol sous des effets sismiques et des forces vibratoires. Essais au laboratoire. Influence des divers paramètres sur le modèle initial et l'amortissement. Résultats des mesures. Influence de la vitesse de déformation sur la résistance des matériaux
Author: Etienne Guyon Publisher: MIT Press ISBN: 026204370X Category : Technology & Engineering Languages : en Pages : 270
Book Description
Explaining the science contained in a simple assembly of grains—the most abundant form of matter present on Earth. Granular media—composed of vast amounts of grains, consolidated or not—constitute the most abundant form of solid matter on Earth. Granular materials assemble in disordered configurations scientists often liken to a bag of marbles. Made of macroscopic particles rather than molecules, they defy the standard scheme of classification in terms of solid, liquid, and gas. Granular materials provide a model relevant to various domains of research, including engineering, physics, and biology. William Blake famously wished “To See a World in a Grain of Sand”; in this book, pioneering researchers in granular matter explain the science hidden behind simple grains, shedding light on collective behavior in disordered settings in general. The authors begin by describing the single grain with its different origins, shapes, and sizes, then examine grains in piled or stacked form. They explain the packing fraction of granular media, a crucial issue that bears on the properties displayed in practical applications; explore small-scale deformations in piles of disordered grains, with particular attention to friction; and present theories of various modes of disorder. Along the way, they discuss such concepts as force chains, arching effects, wet grains, sticky contacts, and inertial effects. Drawing on recent numerical simulations as well as classical concepts developed in physics and mechanics, the book offers an accessible introduction to a rapidly developing field.
Author: Linda Strande Publisher: IWA Publishing ISBN: 1780404735 Category : Technology & Engineering Languages : en Pages : 428
Book Description
It is estimated that literally billions of residents in urban and peri-urban areas of Africa, Asia, and Latin America are served by onsite sanitation systems (e.g. various types of latrines and septic tanks). Until recently, the management of faecal sludge from these onsite systems has been grossly neglected, partially as a result of them being considered temporary solutions until sewer-based systems could be implemented. However, the perception of onsite or decentralized sanitation technologies for urban areas is gradually changing, and is increasingly being considered as long-term, sustainable options in urban areas, especially in low- and middle-income countries that lack sewer infrastructures. This is the first book dedicated to faecal sludge management. It compiles the current state of knowledge of the rapidly evolving field of faecal sludge management, and presents an integrated approach that includes technology, management, and planning based on Sandecs 20 years of experience in the field. Faecal Sludge Management: Systems Approach for Implementation and Operation addresses the organization of the entire faecal sludge management service chain, from the collection and transport of sludge, and the current state of knowledge of treatment options, to the final end use or disposal of treated sludge. The book also presents important factors to consider when evaluating and upscaling new treatment technology options. The book is designed for undergraduate and graduate students, and engineers and practitioners in the field who have some basic knowledge of environmental and/or wastewater engineering.
Author: Jacques Duran Publisher: Springer Science & Business Media ISBN: 1461204992 Category : Science Languages : en Pages : 227
Book Description
This introductory text develops the fundamental physics of the behavior of granular materials. It covers the basic properties of flow, friction, and fluidization of uniform granular materials; discusses mixing and segregation of heterogeneous materials (the famous "brazil-nut problem"); and concludes with an introduction to numerical models. The presentation begins with simple experiments and uses their results to build concepts and theorems about materials whose behavior is often quite counter-intuitive; presenting in a unified way the background needed to understand current work in the field. Developed for students at the University of Paris, the text will be suitable for advanced undergraduates and beginning graduates; while also being of interest to researchers and engineers just entering the field.
Author: Soil Science Society of America Publisher: ASA-CSSA-SSSA ISBN: 9780891188513 Category : Technology & Engineering Languages : en Pages : 96
Book Description
More than 1800 terms are included in this revised glossary. Subject matter includes soil physics, soil chemistry, soil biology and biochemistry, pedology, soil and water management and conservation, forest and range soils, nutrient management and soil and plant analysis, mineralogy, wetland soils, and soils and environmental quality. Two appendices on tabular information and designations for soil horizons and layers also are included.
Author: Trung Kien Nguyen
Author: Trung Kien Nguyen
Author: Nicolas Gland
Author: Mohamed Satee El Hosri
Author: Philippe Claudin
Author: Etienne Guyon
Author: Linda Strande
Author: Jacques Duran
Author: 
Author: Soil Science Society of America
Author: Elisabeth Bouchaud