Author: Damijan Marcovič
Publisher:
ISBN: 9782110950994
Category :
Languages : fr
Pages : 131
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Book Description
Lors de la conception des structures du génie civil et du génie mécanique il est très important de pouvoir prévoir comportement près de leur état ultime. Or, les matériaux utilisés sont souvent fortement hétérogènes, comme par exemple le béton et les métaux composites, et sont en conséquence difficiles à modéliser en cas de sollicitations extrêmes. Dans ce travail nous proposons une nouvelle stratégie multi échelles adaptée pour ce type des problèmes. Selon l'approche on couple un modèle basé sur la méthode des éléments finis (MEF) à l'échelle de la structure (macro) avec un modèle très fin à l'échelle de la microstructure (micro), lui aussi basé sur la MEF. Cela nous permet de modéliser l'échelle micro beaucoup plus fidèlement que ce qui est possible avec les approches phénoménologiques ou avec des méthodes d'homogénéisation analytique. L'inconvénient principal d'une telle approche étant en général le coût de calcul très élévé, nous considérons trois aspects rendant possible une application aux situations réelles. Premièrement, la formulation variationnelle permet de n'utiliser le modèle fin que dans les parties restreintes de la structure, là où les échelles sont vraiment fortement couplées, tout en gardant un modèle homogénéisé ailleurs. Deuxièment, nous adaptons la MEF sur l'échelle micro en employant l'approche dite structurée, avec laquelle on peut réduire le nombre de degrés de liberté d'une manière importante en gardant la même précision. Le troisième aspect porte sur l'implantation de la méthode dans un code de calcul, adaptée pour des machines parallèles, ce qui nous a permis de lancer les analyses d'une taille comparable à celle des situations réelles. Enfin, nous montrons de quelle manière cette approche peut être utilisée dans l'optimisation de forme des inclusions d'un matériau composite.
Author: Damijan Markovič
Publisher:
ISBN:
Category :
Languages : fr
Pages : 258
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Author: Tao Jiang
Publisher:
ISBN:
Category :
Languages : en
Pages : 120
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Book Description
Cette étude est consacrée à la modélisation micromécanique de comportement inélastique des géomatériaux hétérogènes . Une sorte de roche d'argile dure (argilite) est considérée comme un exemple pour valider la modélisation micromécanique. Un bref aperçu des principales techniques d'homogénéisation pour la modélisation multi-échelles développées de matériaux non-linéaire hétérogènes est présenté dans le premier chapitre. Puis quelques résultats numérique des simulations directes FEM sont donnés dans le deuxième chapitre. Dans le chapitre suivant, l'une des approches les plus couramment utilisée de méthodes d'homogénéisation non-linéaire des matériaux hétérogènes non linéaires, approche incrémentale de Hill, est étudiée et appliquée pour simuler le comportement mécanique de l'argilite avec des divers compositions sur différents parcours de chargement. Compte tenu des certains limites théoriques de l'approche incrémentale, une nouvelle méthode d'homogénéisation nommé analyse des champs avec transformation non-uniforme (NTFA) proposé d'abord par Michel et Suquet est adoptée et développée pour s'adapter aux géomatériaux pression-dépendants dans Chapitre 4. Dans ce chapitre, la formulation et la mise en œuvre numérique de la NTFA pour des matériaux hétérogènes composés d'une matrice pression-dépendante de type Drucker-Prager et une inclusion élastique sont présentés. Ensuite, dans le chapitre six une application plus compliquée est réalisée pour simuler le comportement mécanique de l'argilite afin de valiter de la méthode proposée NTFA.
Author: Adnan Ibrahimbegovic
Publisher: Springer Science & Business Media
ISBN: 9048123305
Category : Computers
Languages : en
Pages : 588
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Book Description
This book offers a recipe for constructing the numerical models for representing the complex nonlinear behavior of structures and their components, represented as deformable solid bodies. Its appeal extends to those interested in linear problems of mechanics.
Author: Delphine Brancherie
Publisher: John Wiley & Sons
ISBN: 1786302594
Category : Science
Languages : en
Pages : 304
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Book Description
Mechanical behaviors of materials are highly influenced by their architectures and/or microstructures. Hence, progress in material science involves understanding and modeling the link between the microstructure and the material behavior at different scales. This book gathers contributions from eminent researchers in the field of computational and experimental material modeling. It presents advanced experimental techniques to acquire the microstructure features together with dedicated numerical and analytical tools to take into account the randomness of the micro-structure.
Author: Adnan Ibrahimbegovic
Publisher: Springer Science & Business Media
ISBN: 9048123860
Category : Technology & Engineering
Languages : en
Pages : 390
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Book Description
1.1. SAFETY OF CIVIL STRUCTURES Society expects that the failure of civil structures is extremely rare and relies on the care and expertise of the professionals involved in the design, construction and maintenance of structures. This is in particular true for public technical systems such as transportation or energy supply systems and structures such as bridges. Structural safety may be defined as follows: “Adequate safety with respect to a hazard is ensured provided that the hazard is kept under control by appropriate measures or the risk is limited to an acceptable value. Absolute safety is not achievable.” It is thus not the structure as such that is designated safe but rather the people, goods and the environment in its surroundings. The continued use of existing structures is of great importance because the built environment is a huge economic and political asset, growing larger every year. Nowadays evaluation of the safety of existing structures is a major engineering task, and structural engineers are increasingly called upon to devise ways for extending the life of structures whilst observing tight cost constraints. Also, existing structures are expected to resist against accidental actions although they were not designed for. Engineers may apply specific methods for evaluation in order to preserve structures and to reduce a client’s expenditure. The ultimate goal is to limit construction intervention to a minimum, a goal that is clearly in agreement with the principles of sustainable development.
Author: Wojciech Pietraszkiewicz
Publisher: CRC Press
ISBN: 9780415383905
Category : Technology & Engineering
Languages : en
Pages : 656
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Book Description
Shells are basic structural elements of modern technology. Examples of shell structures include automobile bodies, domes, water and oil tanks, pipelines, ship hulls, aircraft fuselages, turbine blades, laudspeaker cones, but also balloons, parachutes, biological membranes, a human skin, a bottle of wine or a beer can. This volume contains full texts of over 100 papers presented by specialists from over 20 countries at the 8th Conference "Shell Structures: Theory and Applications", 12-14 October, 2005 in Jurata (Poland). The aim of the meeting was to bring together scientists, designers, engineers and other specialists in shell structures in order to discuss important results and new ideas in this field. The goal is to pursue more accurate theoretical models, to develop more powerful and versatile methods of analysis, and to disseminate expertise in design and maintenance of shell structures. Among the authors there are many distinguished specialists of shell structures, including the authors of general lectures: I.V. Andrianov (Ukraine), V.A. Eremeyev (Russia), A. Ibrahimbegovic (France), P. Klosowski (Poland), B.H. Kröplin (Germany), E. Ramm (Germany), J.M. Rotter (UK) and D. Steigmann (USA). The subject area of the papers covers various theoretical models and numerical analyses of strength, dynamics, stability, optimization etc. of different types of shell structures, their design and maintenance, as well as modelling of some surface-related mechanical phenomena.
Author: Michel Fortin
Publisher: American Mathematical Soc.
ISBN: 9780821873281
Category : Technology & Engineering
Languages : en
Pages : 292
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Book Description
This volume features the proceedings from the Summer Seminar of the Canadian Mathematical Society held at Universite Laval. The purpose of the seminar was to gather both mathematicians and engineers interested in the theory or application of plates and shells, or more generally, in the modelisation of thin structures. From this, it was hoped that a better understanding of the problem would emerge for both groups of professionals. New aspects from the mathematical point of view and new applications posing new challenges are reported. This volume offers a snapshot of the state of the art of this rapidly evolving topic.
Author: Christian Miehe
Publisher: Springer Science & Business Media
ISBN: 9401702977
Category : Technology & Engineering
Languages : en
Pages : 487
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Book Description
The steady increase in computational power induces an equally steady increase in the complexity of the engineering models and associated computer codes. This particularly affects the modeling of the mechanical response of materials. Material behavior is nowadays modeled in the strongly nonlinear range by tak ing into account finite strains, complex hysteresis effects, fracture phenomena and multiscale features. Progress in this field is of fundamental importance for many engineering disciplines, especially those concerned with material testing, safety, reliability and serviceability analyses of engineering structures. In recent years many important achievements have been made in the field of the theoretical formulation, the mathematical analysis and the numerical im plementation of deformation processes in solids. Computational methods and simulation techniques today play a central role in advancing the understanding of complex material behavior. Research in the field of "ComputationalMechan ics of Materials" is concerned with the development of mathematical models and numerical solution techniques for the simulation of material response. It is a very broad interdisciplinary field of science with inputs from traditional fields such as Applied Mechanics, Applied Mathematics, Materials Science, Solid State Physics and Information Technology. The intention of the IUTAM Symposium "Computational Mechanics of Solid Materials at Large Strains", held at the University of Stuttgart, Germany, from August 20-24, 200I, was to give a state of the art and a survey about recent developments in this field and to create perspectives for future research trends.
Author: Manolis Papadrakakis
Publisher:
ISBN: 9789602546833
Category :
Languages : en
Pages : 226
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Book Description
