Tesis sobre el tema "Mécanique non linéaire – Simulation par ordinateur"
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Hamlili, Hassane. "Simulation de problèmes de la mécanique non linéaire du solide par éléments finis sur micro-ordinateur". Vandoeuvre-les-Nancy, INPL, 1990. http://www.theses.fr/1990INPL045N.
Texto completoNegrello, Camille. "Méthodes fortement parallèles pour la simulation numérique en mécanique non linéaire des structures". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN049/document.
Texto completoThis thesis is aimed to contribute to the adoption of virtual testing, an industrial practice still embryonic which consists in optimizing and certifying by numerical simulations the dimensioning of critical industrial structures. The virtual testing will allow colossal savings in the design of mechanical parts and a greater respect for the environment, thanks to optimized designs. In order to achieve this goal, new calculation methods must be implemented, satisfying more requirements concerning safety, respect for hardware architectures, fastness, and compatibility with the time constraints of engineering.We are interested in the parallel resolution of large nonlinear problems by domain decomposition methods. Our goal is to approximate the exact solution by minimizing communication between subdomains. In order to do this, we want to maximize the computations performed independently by subdomain, using nonlinear relocation approaches. We also try to control the convergence criteria of the nested solvers in order to avoid over-resolution and divergences, to improve the construction of conditions Of mixed interface, and non-linearizing the preconditioning step of the solver. The ultimate objective being to deal with problems of industrial complexity, the robustness of the methods we develop will be a constant concern.Conventionally, non-linear problems are solved by constructing a sequence of linear systems that can be solved in parallel using iterative methods, such as Krylov solvers. We wish to question this usual procedure by trying to construct a sequence of small independent nonlinear systems to be solved in parallel. Such a technique involves the use of interleaved iterative solvers, whose convergence criteria must be dynamically tuned in order to avoid both over-resolution and loss of convergence. The robustness of the method can be ensured in particular by the use of well-constructed mixed interface conditions and well-chosen preconditioners
Fouial, Karim. "Nouvelle méthode d'interprétation des mesures des contraintes par surcarottage adaptée aux roches à comportement non linéaire ou fracturées". Vandoeuvre-les-Nancy, INPL, 1997. http://www.theses.fr/1997INPL109N.
Texto completoSauvage, Renaud. "Étude des effets de compressibilité à grands nombres de mach par simulation numérique directe d'une couche cisaillée". Toulouse, INPT, 2000. http://www.theses.fr/2000INPT053H.
Texto completoSaad, Roy. "Sur une approche à objets généralisée pour la mécanique non linéaire". Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10137/document.
Texto completoThe problems occurring today in computational mechanics and related domains are complex, and may involve several physics at different time and space scales. The numerical treatment of complex problems is in general tough and time consuming. In this context, the interest to develop methods and tools to accelerate the integration of new formulations into simulation tools is obvious. This work arises on the issue of the development of computational tool. The proposed approach covers the development process of numerical models from the variational statement to the simulation tool. The approach is applied to the finite element method. We have developed generic concepts to automate the development of the finite element method. To achieve this goal, we relied on tensor analysis applied in the context of the finite element method. The mathematical formalism is based on the tensor algebra to describe the discretization of a variational formulation. The generic character of the approach is preserved through the object-oriented approach in Java. We propose a framework based on object-oriented concepts capable of handling symbolic developments of elemental contributions for finite element codes. The advantage of this approach is the generic description that can be extended naturally to any discretization model in space or time. This concept is fully validated for simple linear problems (elasticity, heat convection, ...), for the treatment of mixed variational formulations (thermo-mechanical, Navier-Stokes for incompressible flows...) and Lagrangian frameworks (elasticity in larges transformations, hyperelasticity, ...)
Alsaleh, Hassan. "Modélisation non-linéaire en trois dimensions de l'interaction sol-micropieux-pont sous chargements sismiques". Lille 1, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-Alsaleh.pdf.
Texto completoDesobry, David. "Génération de maillages hexaédriques pour des simulations de grandes déformations". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0163.
Texto completoThis thesis focuses on the development of hexahedral meshing methods suitable for large deformation simulations in non-linear mechanics. Domain parameterization methods based on frame fields are used to generate high-quality hexahedral meshes aligned with the domain boundaries. However, during large deformations, the mesh quality may degrade and potentially block the simulation. This thesis explores the idea of determining an optimal connectivity for the mesh elements while taking into account the anticipated deformations.In 2D, a complete pipeline is developed to tackle this challenge by combining previous work and scientific contributions. In 3D, contributions are made to approach this objective, particularly by controlling the boundary valences of hexahedral meshes produced from frame fields. The different parts of the thesis address the steps of large deformation numerical simulations, the advantages of global parameterization methods, the results of simulations on industrial 2D meshes, and contributions to improving the flexibility and robustness of the hexahedral meshing process.The ultimate goal is to reduce the time spent by engineers in generating an adequate mesh for a simulation by considering a priori information on the deformation to which the mesh and the object will be subjected
Duraffourg, Elodie. "Commande non linéaire en présence de modes souples, applications aérospatiales". Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0048/document.
Texto completoDue to mass constraints aerospace systems tend to have lightweight and flexible structures leading to new control objectives such as structural load reduction. To fulfil these objectives, flexible modes must be considered from the design of the controller, requiring to consider some constraints such as nonlinearities, underactuation, or measurement corruption terms. Consider these constraints, this thesis treats the design of a nonlinear control method for flexible aerospace systems. We particularly focus on the problem of reducing oscillations caused by the bending modes. To do that, we define a class of nonlinear system which is both underactuated and minimum phase and that represents flexible aerospace systems. Consider this class, we propose a nonlinear full-state controller based on changes of coordinates and the backstepping technique. The control design is carried out to enhance the transient of the flexible modes. Flexiblestates being not measured, the output-feedback problem is also treated through adaptive observers (finite-time and asymptotic). Uncertainties of natural damping and frequency of the bending modes are particularly considered. The proposed method is illustrated by numerical simulations performed on a space launch vehicle and an hypersonic aircraft
Gnanga, Honoré. "Analyse numérique d'écoulements turbulents anisotropes à l'aide de modèles non-linéaires de turbulence". Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10057/document.
Texto completoThe aim of this work is to predict numerically the three - dimensional turbulent flows of a Newtonian and incompressible fluid using nonlinear stress - strain models. The Explicit Algebraic Stress Models (EASM), which can take into account the anisotropy of turbulence with less CPU time and computer memory than RSM or approach DNS and LES, are adopted as a turbulence model. Among these models, we choosed Shih et al. (1995) and Craft et a1.(1996) models. These models are studied using a priori and a posteriori investigations. The study is carried out in square duct. This configuration presents a secondary flow and a significant anisotropy between the Reynolds stress components. To predict the significant viscous effects due to the wall and the corner, the damping functions are implemented. The maps of the second and third invariants in the plan of Lumley exhibited show the various states of turbulence and a good anisotropy level obtained. The mean flow field and the turbulent statistics are compared with existing numerical and experimental data for square and rectangular duct flow. The model performance is shown to be satisfactory. ln particular, the mean secondary velocity vectors and stream wise vorticity are well predicted
Yahyaoui, Omar El. "Évaluation de modèles non-linéaires de turbulence à partir de simulations numériques directes des équations de Navier-Stokes". Lille 1, 2003. https://ori-nuxeo.univ-lille1.fr/nuxeo/site/esupversions/b805d85e-4438-419e-b3c7-3b4549924063.
Texto completoMarchand, Basile. "Assimilation de données et recalage rapide de modèles mécaniques complexes". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN053/document.
Texto completoFor several years, the considerable changes that have occurredin computing tools have led to new practices in the simulation of mechanical structures. Among them, the motivation for this work is the Dynamic Data Driven Application Systems paradigm (DDDAS). The founding idea of this approach is to establish a dialogue between a physical system and its numericalmodel. The objective is then to (i) allow a calibration of the numerical model by means of measurements performed on the physical system; (ii) control the evolution of the physical system using theprediction given by numerical simulation. The major difficulty is to realize this dialogue in real time. This work focuses on the model updating step of the DDDAS paradigm. The problem is then to develop methods and tools to solve inverse problems taking into account various constraints, namely: (i) robustness with respect to corrupted data; (ii) genericity for considering a wide variety of problems and mechanical models; (iii) a reduced computation time in order to tend towards a real-time model updating.The starting point of this work is the modified Constitutive Relation Error, an energetic approach dedicated to the solution of inverse problems in mechanics, notably illustrated by its robustness with respect to measurement noises. First, in order to guarantee a fast identification process, we have coupled the modified Constitutive Relation Error with the PGD model reduction in the linear model framework, thus enabling a fast and automatic identification process. Then, in order to be applied to the DDDAS paradigm, we have developed an identification method based on a data assimilation process (the Kalman filter) and using the modified Constitutive Relation Error as an observer alwayswithin the framework of linear problems. We have then extended this data assimilation approach to the problem of the identification of parameter fields by introducing a separation of the spatial discretizations and by introducing tools resulting from the mesh adaptation framework. We have then addressed the problem of non-linear mechanical models, through damage and visco-plasticitymodels. To this end, we have first recast and extended the concept of the modified Constitutive Relation Error to this nonlinear material framework and we have implemented a dedicated resolution process, based on the LaTIn method. Finally, we have introduced this reformulation of the modified Constitutive Relation Error in the previously data assimilation method in order to process the model updating of nonlinear models
Danan, David. "Modélisation, analyse et simulations numériques de quelques problèmes de contact". Thesis, Perpignan, 2016. http://www.theses.fr/2016PERP0015/document.
Texto completoContact phenomena between bodies, whether they are deformable or not, abound in everyday life. Their modellings require mathematical tools using systems of partial differential equations and involving complex boundary conditions, in order to describe the contact. While the physical aspects of such phenomena have been known for a long time, the mathematical theory remains relatively recent which leaves room for numerous problems. This work focuses on the modelling, the analysis and the numerical simulations of such problems. It is located halfway between contact mechanics and the mathematical aspects inherent to the mechanical questions involved. Our aim is to study several groups of problems that include original contact conditions (with or without friction), both from a mathematical and numerical point of view, in order to contribute to the theory, and also to highlight several numerical methods used to solve specific contact problems
Aheto, Kouassivi. "Conception et analyse non linéaire des oscillateurs à quartz ultrastables". Besançon, 1990. http://www.theses.fr/1990BESA2048.
Texto completoBarbié, Laureline. "Raffinement de maillage multi-grille local en vue de la simulation 3D du combustible nucléaire des Réacteurs à Eau sous Pression". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4742.
Texto completoThe aim of this study is to improve the performances, in terms of memory space and computational time, of the current modelling of the Pellet-Cladding mechanical Interaction (PCI),complex phenomenon which may occurs during high power rises in pressurised water reactors. Among the mesh refinement methods - methods dedicated to efficiently treat local singularities - a local multi-grid approach was selected because it enables the use of a black-box solver while dealing few degrees of freedom at each level. The Local Defect Correction (LDC) method, well suited to a finite element discretisation, was first analysed and checked in linear elasticity, on configurations resulting from the PCI, since its use in solid mechanics is little widespread. Various strategies concerning the implementation of the multilevel algorithm were also compared. Coupling the LDC method with the Zienkiewicz-Zhu a posteriori error estimator in orderto automatically detect the zones to be refined, was then tested. Performances obtained on two-dimensional and three-dimensional cases are very satisfactory, since the algorithm proposed is more efficient than h-adaptive refinement methods. Lastly, the LDC algorithm was extended to nonlinear mechanics. Space/time refinement as well as transmission of the initial conditions during the remeshing step were looked at. The first results obtained are encouraging and show the interest of using the LDC method for PCI modelling
Mouille, Pascal. "Commande non linéaire de paliers magnétiques". Chambéry, 1994. http://www.theses.fr/1994CHAMS004.
Texto completoBonelli, Stéphane. "Contribution à la résolution de problèmes élastoplastiques de mécanique des sols et d'écoulements non saturés par la méthode des éléments finis". Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX22038.
Texto completoAuburtin, Christian. "Analyse linéaire et non-linéaire de structures poutres planes par éléments finis et méthodes multigrilles sur micro-ordinateur". Vandoeuvre-les-Nancy, INPL, 1990. http://www.theses.fr/1900INPL040N.
Texto completoDandache, Mohamad. "Stabilisation arbitraire par retour de sorties". Chambéry, 1998. http://www.theses.fr/1998CHAMS023.
Texto completoSioud, Khaled. "Simulation par éléments finis sur micro-ordinateur de la réponse dynamique des structures coques en régime linéaire et non linéaire". Nancy 1, 1991. http://www.theses.fr/1991NAN10127.
Texto completoCherubini, Stefania. "Linear and non-linear global instability of attached and separated boundary-layer flows over a flat plate". Paris, ENSAM, 2010. http://www.theses.fr/2010ENAM0012.
Texto completoLe but de cette thèse est de décrire en détail la dynamique linéaire et non linéaire d'une couche limite attachée sur une plaque plane à bas nombre de Reynolds. La dynamique linéaire, pilotée par les interactions entre les vecteurs propres non-orthogonaux, est étudiée à travers deux méthodes différentes d’instabilité globale : une analyse globale aux vecteurs propres et une optimisation directe-adjointe. Dans ces analyses globales, aucune structure spatiale n’est imposée à priori pour la perturbation, les effets convectifs dus au fort non parallélisme de l’écoulement sont pris en compte. Pour le cas de la couche limite décollée, le déclenchement des instationnarités a été clarifié : i) pour une forte amplification des perturbations de nature convective et bidimensionnelle ; ii) pour des effets de non normalité longitudinale engendrant le phénomène du flapping ; iii) pour une forte sensibilité vis-à-vis d’un forçage harmonique ; iv) pour un monde tridimensionnel globalement instable. Pour une couche limite attachée, le but a été d’identifier les perturbations localisées caractérisées par des fréquences multiples dans les directions longitudinales et transversales de l’écoulement, induisant une amplification de l’énergie des perturbations. Pour évaluer les effets les effets de la non linéarité dans les mécanismes d’instabilité identifiés par les analyses de stabilité globale, des simulations numériques directes ont été réalisées pour les écoulements de couche limite attachées ou décollées, bidimensionnelles et tridimensionnelles. La dynamique des perturbations permettant une plus rapide vers la turbulence a été étudiée. Différents scénarios de transition ont été observés, les différents mécanismes de transition ont été analysés
Ngo-Ngoc, Cyril. "Modélisation non linéaire et simulation des matériaux souples textiles : application aux essais Kawabata". Lille 1, 2003. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2003/50376-2003-13.pdf.
Texto completoTrifonov, Andrey. "Contrôle non destructif par des méthodes d'acoustique non linéaire pour des applications aéronautiques". Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0006/document.
Texto completoThis PhD thesis work contributes to the development of nonlinear elastic methods for non-destructive testing and imaging of contact-type defects in solids.In this work, two modifications of recent nonlinear nondestructive testing methods are suggested: the coda wave interferometry combined with the nonlinear time reversal principle and air-coupled nonlinear ultrasonic imaging. The principal advantage of former technique is in its extremely high sensitivity owing to the fact that weak changes in sample's parameters are accumulated and finally greatly amplified during the formation of the coda wave. The other technique has a complimentary strength and offers a possibility of a remote detection. The developed techniques are tested on samples with artificially fabricated defects at known locations. The performance of each method is accessed and the potential for obtaining robust nonlinear images is demonstrated.The second part of the work is concerned with a theoretical description of contact acoustical nonlinearity and its use for creating of a numerical toolbox capable of simulating wave propagation in complex structures containing internal contacts. A physical model describing the tangential shift of two contacting bodies in the presence of friction has been proposed. Its result is an analytical computer-assisted solution for hysteretic relationships between normal and tangential contact displacements and loads. The contact model and derived load-displacement relationships are used as boundary conditions posed at the internal boundaries (contact surfaces) in a finite element wave propagation model programmed via commercial software
Nocent, Olivier. "Animation dynamique de corps déformables continus : Application à la simulation de textiles tricotés". Reims, 2001. http://www.theses.fr/2001REIMS026.
Texto completoInou, Allal. "Modélisations numériques d'oscillateurs paramétriques optiques, en régime de fortes conversions, à l'échelle nanoseconde". Limoges, 1998. http://www.theses.fr/1998LIMO0013.
Texto completoGhozzi, Yosr. "Simulation numérique des problèmes mécaniques non linéaires par approche mixte MEF-MESHLESS". Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0006/document.
Texto completoIn this work, we implement a development of mixed discretization MEF-Meshless for solving strongly nonlinear mechanical problem. Particular attention is given to the construction of the shape functions by diffuse approximation. In order to deal with problems of solid mechanics with large strain, we develop a so-called “mixed” numerical method combining both Meshless to discretize areas of high deformation gradient, and Finite Element Method (MEF) for non-concerned areas. We ensure coupling between both discretization methods through the implementation of specific techniques, including the continuity and consistency of the field and the choice of the appropriate method of numerical integration. We test later the reliability and performance of the model by the introduction of a comparative study with a standard FEM model designed for the same numerical conditions to evaluate numerical techniques attributed to our “mixed” model. We develop, thereafter, a model of behavior through a large strain description. We adopt spatial discretization elements “assumed strain” and a suitable time discretization. To validate our “mixed” model, we perform a comparative study of nonlinear simple calculation examples
Liard, Laurent. "Transport non linéaire dans un réacteur Hélicon". Phd thesis, Ecole Polytechnique X, 2009. http://pastel.archives-ouvertes.fr/pastel-00005954.
Texto completoLabit, Yann. "Contribution à la commande non linéaire par des approches linéaires". Phd thesis, INSA de Toulouse, 2002. http://tel.archives-ouvertes.fr/tel-00131792.
Texto completoSaavedra, Redlich Karin. "Stratégie multiéchelle pour l'analyse du couplage flambage-délaminage de composites stratifiés". Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-00719119.
Texto completoGentot, Laëtitia. "Adoucissement par fatigue des milieux élastomères : caractérisation, modélisation et simulation numérique". Lille 1, 2003. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2003/50376-2003-207-208.pdf.
Texto completoTrombini, Marion. "Couplage endommagement-grandes déformations dans une modélisation multi-échelle pour composites particulaires fortement chargés". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2015. http://www.theses.fr/2015ESMA0002/document.
Texto completoThis study is devoted to multi-scale modeling of highly-filled particulate composites.This method, the “Morphological Approach” (M.A.), is based on a geometrical and kinematicalschematization which allows the access to both local fields and homogenized response. In order toevaluate the predictive capacities of the M.A. considering a linear elastic behavior for the constituentsand evolution of damage, analysis is performed regarding the ability of the M.A. to accountfor particle size and interaction effects on debonding chronology. For that purpose, simple periodic,random monomodal and bimodal microstructures are considered. The results are consistent withliterature data : debonding of large particles occurs before the one of smaller particles and thehigher the particle volume fraction, the sooner the debonding. Finally, the objective is to operatethe coupling of two non linearities which were separately studied in previous versions of the M.A. :debonding between particles and matrix, and finite strains. The whole analytical background of theapproach is reconsidered in order to define the localization-homogenization problem. The nucleationcriterion is extended to the finite strains context. The final problem, strongly non linear, is numericallysolved through a Newton-Raphson algorithm. The different solving steps (jacobian matrix,coding with Python®) are developed. Progressive evaluations (sound and damage materials) allowthe validation of numerical implementation. Then, size and interaction effects are reproduced infinite strains
Clavel, Jean-François. "Modélisation en dynamique transitoire non-linéaire par la méthode des éléments finis en schéma d'intégration explicite sur micro-ordinateur". Nancy 1, 1998. http://www.theses.fr/1998NAN10114.
Texto completoSornin, Denis. "Sur les formulations élastoplastiques non locales en gradient d'endommagement". Troyes, 2007. http://www.theses.fr/2007TROY0011.
Texto completoFEM results of softening materials are well known to show pathological mesh dependency. The main goal of the present work, studying different types of formulation, is to give some elements to choose the better models able to avoid mesh sensitivity. A general study of the different sources of mesh and time dependency is carried out, and some existing solutions are presented. The case of elastoplastic damaging models with destination to industrial applications is specifically studied in the rest of the thesis. Formulations are presented and studied for a simple tension test, with various spatial discretisation. Numerical aspects and implementation in ABAQUS-standard environment is discussed. A new non local element is used for some of the formulations. The structure and details of this element are presented. For a given set of meshes, the ability of each formulation presented to control the size of the necking zone is studied. In the same time the independence of the global dissipation to the mesh size is checked. Practical and theoretical limits are highlighted. This study, gives some scientific and practical elements for the choice of a non local elastoplastic damaging model able to avoid discretisation sensitivity. For the end, the principal conclusions and the better developments in prospect are given
Tissier, Marion. "Etude numérique de la transformation des vagues en zone littorale, de la zone de levée aux zones de surf et de jet de rive". Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14437/document.
Texto completoIn this thesis, we introduce a new numerical model able to describe wave transformation from the shoaling to the swash zones, including overtopping. This model is based on Serre Green-Naghdi equations, which are the basic fully nonlinear Boussinesq-type equations. These equations can accurately describe wave dynamics prior to breaking, but their application to the surf zone usually requires the use of complex parameterizations. We propose a new approach to describe wave breaking in S-GN models, based on the representation of breaking wave fronts as shocks. This method has been successfully applied to the Nonlinear Shallow Water (NSW) equations, and allows for an easy treatment of wave breaking and shoreline motions. However, the NSW equations can only be applied after breaking. In this thesis, we aim at extending the validity domain of the NSW model SURF-WB (Marche et al. 2007) to the shoaling zone by adding the S-GN dispersive terms to the governing equations. Local switches to NSW equations are then performed in the vicinity of the breaking fronts, allowing for the waves to break and dissipate their energy. Extensive validations using laboratory data are presented. The new model, called SURF-GN, is then applied to study tsunami-like undular bore dynamics in the nearshore. The model ability to describe bore dynamics for a large range of Froude number is first demonstrated, and the effects of the bore transformation on wave run-up over a sloping beach are considered. We finally present an in-situ study of broken wave celerity, based on the ECORS-Truc Vert 2008 field experiment. In particular, we quantify the effects of non-linearities and evaluate the predictive ability of several non-linear celerity models
Michaud, Pierre-Yohan. "Distorsions des systèmes de reproduction musicale : Protocole de caractérisation perceptive". Phd thesis, Aix-Marseille Université, 2012. http://tel.archives-ouvertes.fr/tel-00806288.
Texto completoProust, Sébastien. "Ecoulements non-uniformes en lits composés : effets de variations de la largeur du lit majeur". Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0083/these.pdf.
Texto completoFlooding rivers usually present transition reaches where the floodplain width can significantly vary. The present work focuses on both physical and numerical modeling of over bank flows in such configurations. A particular attention is paid to flows in the flood plain. These flows are characterized by turbulent exchanges due to the velocity gradient between flows in the main channel and the floodplain, and by severe mass transfer and associated momentum exchange between the subsections. New experiments are carried out in non-prismatic compound channel flumes: flows in abrupt contraction of the flood plain, enlarging flood plains, flow in the vicinity of groynes. In addition to conventional 1D and 2D simulations, a new modeling is presented: it is called “1D Per Subsection Method” and separates the dynamic equations in each bed. The simulations of both water depth and discharge rate in the floodplain are in good agreement with experimental data, for eight tested geometries
Choi, In-Sung. "Simulation des mécanismes complexes en C. M. A. O. . : Étude des non-linéarités de comportement : Application aux boites de transmission de puissance d'hélicoptères". Lyon, INSA, 1993. http://www.theses.fr/1993ISAL0034.
Texto completoThe study of the global behaviour of mechanisms such as helicopter and autombile gearboxes showed that the highly non-linear behaviour of bearings prevents from isolating the bearings from the rest of the structure for a precise study in term of stresses and of displacements. An approach of the modelling of bearings and of their environment with consideration of the deformation of the rings is proposed. This approach, which is based upon the Finite Element Method (FEM), gives real boundary conditions for fine study of components optimizations. It permits to quantify the mutual influence between the bearings and the real environment. The realization of prototypes and of experiences requires delays and costs high. A software with pre- and post-processors (automatic meshing, visualization,. . . ) for CAD adapted to the industrial Design Offices permits to reduce sensibly these constraints and increases the knowledge of the real behaviour of the mechanism
Filippini, Andrea Gilberto. "Free surface flow simulation in estuarine and coastal environments : numerical development and application on unstructured meshes". Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0404/document.
Texto completoCes dernières décennies, une attention particulière a été portée sur la modélisation mathématique et la simulation numérique de la propagation de vagues en environnements côtiers. Une description physiquement correcte des phénomènes à grande échelle, qui apparaissent dans les régions d'eau peu profonde, doit prendre en compte de forts effets non-linéaires et dispersifs, ainsi que l'interaction avec des bathymétries complexes. Dans un premier temps, une étude du comportement en régime non linéaire de différents modèles de type Boussinesq est proposée, démontrant l'avantage d'utiliser des modèles fortement non-linéaires par rapport à des modèles faiblement non-linéaires et faiblement dispersifs (couramment utilisés). Ensuite, une nouvelle approche flexible pour résoudre les équations fortement non-linéaires et faiblement dispersives de Green-Naghdi est présentée. Cette stratégie permet d'améliorer un code "shallow water" existant par le simple ajout d'un terme algébrique dans l'équation du moment et est particulièrement adapté à l'utilisation de techniques hybrides pour le déferlement des vagues. De plus, la première discrétisation des équations de Green-Naghdi sur maillage non structuré est proposée via des schémas hybrides Volume Fini/Élément Fini. Finalement, les modèles et méthodes développés dans la thèse sont appliqués à l'étude du problème physique de la formation du mascaret dans des estuaires convergents et alluviaux. Cela a amené à la première caractérisation d'estuaire naturel en terme d'apparition de mascaret
Hanique-Cockenpot, Gaël. "Etude numérique de la propagation non linéaire des infrasons dans l'atmosphère". Thesis, Ecully, Ecole centrale de Lyon, 2011. http://www.theses.fr/2011ECDL0032/document.
Texto completoThis thesis proposes a study of non linear infrasound propagation through the atmosphere by a time integration of compressible fluid mechanics equations using aeroacoustics algorithms. The survey is restricted to the case of infrasound emitted by high amplitude explosions. Existing literature is reviewed to identify influential physical phenomena and to detail a realistic atmosphere model compatible with direct numerical methods. Afterwards, the Navier-Stokes equations are formulated to take non-equilibrated vibrational relaxation effects into account. Acoustic absorption and effects of high-scale atmospheric in homogeneities are then discussed on the basis of analytical developments. Subsequently, the optimized numerical methods implemented in the solver are introduced. Numerical stability and accuracy are analyzed, then the method is validated by series of simple configuration simulations and an adapted discretization is proposed to simulate non linear infrasound propagating in the atmosphere. The solver is validated in the configuration of a complex realistic atmosphere, first by a grid convergence method and second by confronting the results to those of other numerical approaches. The influence of acoustic absorption and non linear effects are then discussed by analyzing numerical results. General influence of winds is also introduced and specific phenomena, such as partially reflected waves or creeping waves, are evoked. Finally, simulations are compared with a full-scale experience and similarities between both kind results are underlined
Taki, Abdelmajid. "Ordre et désordre dans un milieu non linéaire perturbé : le cas de "Sine-Gordon"". Nice, 1987. http://www.theses.fr/1987NICE4139.
Texto completoBochud, Pascal. "Résolution spatiale non uniforme dans une méthode vortex et optimisation d'un concept de turbine à aile oscillante". Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25597/25597.pdf.
Texto completoGatard, Emmanuel. "Analyse des phénomènes physiques dans les diodes p-i-n : contribution à la modélisation électrothermique pour les applications de puissance RF et hyperfréquences". Limoges, 2006. http://aurore.unilim.fr/theses/nxfile/default/0b9b8206-a9ad-4e98-8108-afdd5506fda2/blobholder:0/2006LIMO0065.pdf.
Texto completoP-I-N diodes are widely used in active, passive microwave applications including phase shifters, switches, attenuators and limiters. An accurate prediction of electrical behavior, reliability and thermal management of semiconductor power devices goes through the coupling of thermal models with electrical models. Conventional p-i-n diode models at microwave frequencies are simply current controlled resistance without nonlinear effect and temperature dependence. In this context, the diode electrical behavior was largely studied thanks to physics-based simulations. Thus, a nonlinear electrical model was developed in forward as in reverse bias operation and implemented in a commercial circuit simulator. A nonlinear thermal reduced model of the diode was also developed from a 3D finite element description and implemented in a circuit simulator. Finally, a nonlinear electrothermal p-i-n diode model was proposed and successfully validated with small and large signal measurements. The developed model was used to enable the simulation of high power S band limiters
Peng, Shuiran. "Analyse mathématique et numérique de plusieurs problèmes non linéaires". Thesis, Poitiers, 2018. http://www.theses.fr/2018POIT2306/document.
Texto completoThis thesis is devoted to the theoretical and numerical study of several nonlinear partial differential equations, which occur in the mathematical modeling of phase separation and micro-electromechanical system (MEMS). In the first part, we study higher-order phase separation models for which we obtain well-posedness and dissipativity results, together with the existence of global attractors and, in certain cases, numerical simulations. More precisely, we consider in this first part higher-order Allen-Cahn and Cahn-Hilliard equations with a regular potential and higher-order Allen-Cahn equation with a logarithmic potential. Moreover, we study higher-order anisotropic models and higher-order generalized Cahn-Hilliard equations, which have applications in biology, image processing, etc. We also consider the hyperbolic relaxation of higher-order anisotropic Cahn-Hilliard equations. In the second part, we develop semi-implicit and implicit semi-discrete, as well as fully discrete, schemes for solving the nonlinear partial differential equation, which describes both the elastic and electrostatic effects in an idealized MEMS capacitor. We analyze theoretically the stability of these schemes and the convergence under certain assumptions. Furthermore, several numerical simulations illustrate and support the theoretical results
Hemmati, Sahar. "Etude de l'Interaction Sol-Végétation-Atmosphère avec une approche couplée Thermo-Hydro-Mécanique". Phd thesis, Ecole des Ponts ParisTech, 2009. http://pastel.archives-ouvertes.fr/pastel-00005609.
Texto completoArson, Chloé. "Étude théorique et numérique de l'endommagement thermo-hydro-mécanique des milieux poreux non saturés". Phd thesis, Ecole des Ponts ParisTech, 2009. http://pastel.archives-ouvertes.fr/pastel-00005608.
Texto completoHelin, Lionel. "Développement de modèles algébriques explicites pour les fluides viscoélastiques". Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376-2006-Helin.pdf.
Texto completoZoheir, Cif Allah. "Modélisation et simulations numériques de problèmes non linéaires en physique des plasmas : applications à l'équation de Korteweg-De Vries et à l'équation de Schrödinger non linéaire". Nancy 1, 1991. http://www.theses.fr/1991NAN10008.
Texto completoGillieaux, Olivier. "Modélisation des éléments non linéaires dans la simulation des convertisseurs statiques d'énergie". Toulouse, INPT, 1998. http://www.theses.fr/1998INPT017H.
Texto completoChevillot, Fabrice. "Dynamique non-linéaire des instabilités vibratoires induites par le frottement dans les freins aéronautiques : études numériques et confrontations essais-simulations". Thesis, Ecully, Ecole centrale de Lyon, 2009. http://www.theses.fr/2009ECDL0027.
Texto completoThis study deals with the linear and non-linear transient analyses of instabilities induced by friction in aircraft braking systems. The investigation of these instability phenomena, under experimental and theoretical considerations, is useful to design brakes in which vibrations will not be harmful. The aim of this thesis is to predict the amplitude of the oscillations generated by frictioninduced instabilities in an aircraft braking system. To achieve this, a non-linear analytical model of the brake is built in order to reproduce the mechanisms responsible for friction-induced vibrations. Experimental records of the brake under working conditions performed by Messier-Bugatti- SAFRAN Group allow identifying two main vibrations identified in the 0-1,000 Hz range : squeal and whirl. The work is focused on these two phenomena. The first step in the study of a vibration problem is a stability analysis obtained by calculation of the eigenvalues of the Jacobian matrix of the system of non-linear equations linearized at the equilibrium point. The stability of the brake is then investigated with respect to brake parameters : coefficient of friction, hydraulic pressure, non-linear stiffness, etc... In particular, the effects of damping in mode-coupling instabilities are assessed. It appears that the addition of damping into the equations of motion does not lead systematically to the stabilization of the system, which runs counter to the generally accepted idea. The second step concerns the non-linear dynamics. If the system is unstable, the stability analysis gives no information on the amplitude of the oscillations or on the non-linear transient behavior. By integration of the full set of non-linear equations, the stationary and transient regimes are computed. The sensibility of the non-linear response of the brake is then studied with respect to brake parameters. In particular, the effects of damping are investigated in details : the conclusions established on the stability analysis are extended to the non-linear dynamics. Complex non-linear transient behaviors when several instabilities occur are also highlighted and analyzed. Finally, experimental tests reveal that the brake can generate vibrations of various amplitude, although the experimental conditions are identical. The introduction of statistical laws in the braking parameters allow simulating with a good agreement the variability of the vibratory levels observed when a series of tests is performed
Lambert, Yvan. "Étude de l'endommagement en pointe de fissure dans le cas de la fissuration en plasticité non confinée". Compiègne, 1986. http://www.theses.fr/1986COMPI230.
Texto completoRobert, Florent. "Contribution à l'analyse non linéaire géométrique et matérielle des ossatures spatiales en Génie Civil : application aux ouvrages d'art". Lyon, INSA, 1999. http://theses.insa-lyon.fr/publication/1999ISAL0032/these.pdf.
Texto completoIn the field of civil engineering, the current trend to design structures more and more slender and the need to reduce the quantities of material, lead designers to make nonlinear calculations taking into account of the nonlinearities of the System. In the field of engineering structures, considering both material and geometrical nonlinearities is essential, therefrom the necessity to have computer tools fitting the profession and solving that problem. We propose a space convected coordinates based formulation consisting in breaking up the movement of a particle into a large rigid body movement and a small movement inducing strains. Large displacements and large rotations are taken into account for tridimensional beam éléments, whereas the material nonlinearity is based on the hypothesis of small strains. We can modelize space frames made of métal, of reinforced concrète or prestressed concrète. Delayed effects, that are concrète shrinkage and creep and prestressed concrète steel relaxation, are integrated in the général resolution scheme. In order to simulate the engineering structures construction and to study their statics, we consider large displacements for articulations, and we develop a spécifie beam élément that simulâtes correctly the behaviour of weighty cables, even though when not tensed. From the initial stress matrix, we develop the linear instability calculation. We propose the possible extension of our resolution scheme from static loads to dynamic ones. We validate our approach by comparing the results of our calculations tô the expérimental results or the theoretical solution of représentative tests. At last, an example of use of the programme on a real project is shown : the simulation of the replacement of the suspension System of the Tancarville Bridge