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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Shake table Seismic Performance Assessment and Fragility Analysis of Lightly Reinforced Concrete Block Shear Walls

Mojiri, Saeid January 2013 (has links)
<p>This thesis reports on shake table tests on fully-grouted reinforced masonry (RM) shear walls. The test walls covers a range of design parameters to facilitate benchmarking, a thorough performance investigation, and calibration of numerical models as well as development of fragility curves within the context of Performance Based Seismic Design (PBSD). The details of the experimental program undertaken, including general observations in terms of cracking patterns and failure modes of the tested walls and the results on the lateral strength, hysteretic response, dynamic properties, and the contribution of different displacement components to the response of the walls, are presented. More detailed analyses include seismic performance quantification of the walls in terms of inelastic behaviour characteristics, various energy components, and the effective dynamic properties of the tested walls. The analysis is concluded with development of simplified nonlinear response history analytical models and seismic fragility assessment tools for the tested walls. In general, the study results indicated that the displacement ductility capacity of the RM walls and their capability to dissipate energy through plastic hinging are higher than what is currently recognized by the National Building Code of Canada (NBCC). The fragility assessment study further indicated that similar walls are expected to conform to the current drift limits of the NBCC even at high seismic regions in Canada. The results of this study are expected to contribute to the growing Seismic Performance Database (SPD) of RM Seismic Force Resisting System (SFRS), and to the understanding of the lightly reinforced masonry wall system behaviour.</p> / Master of Applied Science (MASc)
42

Effets de charge et de géométrie sur le bruit d'interaction rotor-rotor des doublets d'hélices contra-rotatives / Effects of loading and geometry on the rotor-rotor interaction noise of counter-rotating propellers

Giez, Justine 08 February 2018 (has links)
Le développement de systèmes de propulsion alternatifs aux turboréacteurs actuels constitue un axe de recherche important dans le contexte aéronautique. L’open-rotor, moteur à hélices contrarotatives, constitue une piste sérieuse car il permet à la fois de réduire fortement la consommation de carburant et les émissions de gaz. Toutefois, les émissions sonores restent un défi pour ce type d’architecture, notamment du fait de l’absence de carénage. La compréhension des sources acoustiques et leur prévision est nécessaire afin de pouvoir, par la suite, réduire le bruit de ces moteurs. Les écoulements d’un doublet d’hélices contrarotatives sont complexes, en particulier pour l’hélice aval qui constitue l’axe d’étude de la thèse. Le travail présenté est dédié à une étude numérique, expérimentale et analytique et intervient dans le cadre de la chaire industrielle ADOPSYS entre Safran Aircraft Engines et l’Ecole Centrale de Lyon. L’objectif de ce travail est double. Il s’agit d’une part de réaliser une campagne expérimentale afin d’observer et de mieux comprendre le comportement de l’écoulement et de l’acoustique d’une pale en flèche, notamment en réponse à la présence d’un tourbillon de bord d’attaque. Un second objectif de la thèse était de constituer une base de données afin de comparer les prévisions obtenues avec un modèle analytique. Une méthode de calcul semi-analytique de la réponse aéroacoustique d’une pale aval en réponse à une excitation provenant de l’amont et prenant en compte les effets de charge et de géométrie a été développée. Une étude numérique d’un doublet d’hélices contrarotatives a servi de base à la définition de la géométrie de pale utilisée pendant l’étude. Celle-ci a été définie de façon à observer un tourbillon de bord d’attaque pour certains angles d’incidence. La maquette a ensuite été placée dans une soufflerie anéchoïque de l’Ecole Centrale de Lyon afin de réaliser une étude paramétrique. Des visualisations par enduit visqueux et des mesures de pression pariétale permettent de rendre compte de la présence du tourbillon de bord d’attaque à certains angles d’incidence. L’étude des spectres en champ lointain permet de distinguer un comportement en trois régimes, associés aux trois comportements du tourbillon de bord d’attaque. Des mesures de localisation de sources permettent de corroborer ces observations. Des prévisions analytiques du bruit émis par la pale et se basant sur le modèle d’Amiet ont également été réalisées. Dans un premier temps, les effets de la flèche sont pris en compte dans le modèle et celui-ci est alors appliqué à la pale de l’étude. Une meilleure adéquation des résultats est alors trouvée quand les effets de flèche sont pris en compte, en particulier dans les directions perpendiculaires à la pale. Le modèle est ensuite étendu afin de prendre en compte les effets de la jonction en pied de pale. Cette partie est exploratoire et le développement reste à approfondir. Un complément à l’expérience a consisté en l’étude de l’impact de sillages défilants sur la pale. Un système de barreaux rotatifs permet de générer des sillages périodiques représentatifs d’une interaction de sillages rotor-rotor. Les mesures réalisées montrent le comportement quasi-stationnaire du tourbillon. / The development of alternative propeller systems to turbojets is a main issue for research in the current context of aeronautical transport. Counter rotating open rotors are a candidate solution because they allow reduction of fuel consumption and gas emission. However, noise emissions are still a challenge for these types of configuration, in particular because they cannot benefit from the nacelle and the liners currently used in turbojet. The understanding of acoustic sources and their prediction is necessary in order to be able to reduce noise emission in the near future. Flows in an open-rotor are complex, in particular for the downstream propeller which is the subject of this approach.This work based on a numerical, experimental and analytical study and takes part in the ADOPSYS chair between Safran Aircraft Engines and l’Ecole Centrale de Lyon. This PhD has two main goals. The first one is to complete an experimental study in order to elucidate the behavior of the flow on a swept airfoil and the resulting acoustics, with a possibly developing leading-edge vortex. The measurements will be a data base for further comparison with analytical prediction. The second objective of the PhD consists in developing a semi-analytical modeling of the noise emitted by an airfoil in response to an incoming perturbation, taking into account the loading and geometry effects. A numerical study of a full counter-rotating system was used as a basis for designing the investigated airfoil. The latter was designed so that a leading-edge vortex could be formed on the surface for some angles of attack. The mock-up was then tested in an anechoic wind tunnel of Ecole Centrale de Lyon for various sets of parameters. Flow visualization and wall-pressure measurements indicated the presence of the leading-edge vortex for some angles of attack. The far-field measurements indicated three acoustic regimes, which can be associated with three behaviors of the leading-edge vortex. Source localization measurements corroborate these observations. Analytical predictions of the noise emitted by the airfoil and based on Amiet’s model were also performed. Firstly, the sweep angle is taken into account in the model. Secondly it is applied to the studied airfoil. A better match of the results is found when the sweep is considered, in particular in the perpendicular directions. The model in then extended in order to include the wall-junction. This part is exploratory and should be further developed. Finally, a complementary experimental investigation of the impingement of periodic wakes on the airfoil has been performed, using a system made of rotating bars, mimics true wake interactions. The measurements suggest that the leading-edge vortex has a quasi-steady behavior.
43

Uma metodologia analítico-determinística para a avaliação de desempenho no tempo de processadores de rede implementados como sistemas-sobre-silício. / An analytical deterministic methodology for the performance evaluation of network processors deployed as systems-on-chip.

Faria, Frederico de 26 June 2007 (has links)
O grande aumento da capacidade de integração de transistores em um único circuito integrado tem exigido grande e constante evolução na metodologia de projeto e práticas de implementação de sistemas eletrônicos embarcados. Tal capacidade de integração resultou no surgimento de sistemas sobre silício (SoCs). O projeto de tais sistemas, mais complexos que seus predecessores, alteram significativamente os fluxos tradicionais de concepção de sistemas, fazendo surgir estratégias tais quais reuso, projetos orientados a plataformas, assim como modelagens e simulações em diferentes níveis de abstração. Um dos diferentes níveis de abstração estudados é o analítico, onde os sistemas são modelados através de representações abstratas. A adoção de modelos analíticos apresenta vantagens, como alta velocidade de execução (permitindo um grande número de análises de modelos diferentes) e facilidade de alteração. No entanto, por se tratarem de modelagens distantes, em termos de abstração, de implementações reais, podem oferecer prognósticos não exatos. Faz-se então necessária a investigação de metodologias que tenham como propósito o aperfeiçoamento de tais modelos em termos de acurácia e fidelidade. O presente trabalho apresenta uma metodologia de modelagem analítica para avaliação de desempenho de sistemas-sobre-silício orientada a aplicação de processadores de redes de pacotes. A metodologia de Network Calculus, a ser implementada nos estágios iniciais de projeto de sistemas-sobre-silício baseados em plataforma, contribui para reduzir o espaço de avaliação de projeto. Trata do equacionamento analítico de representações abstratas das cargas de entrada e também da capacidade de processamento de recursos, visando obter prognósticos mais pessimistas e mais otimistas de parâmetros como latência, requisição de buffer e utilização do sistema, descrito de modo abstrato através de grafos. / The great increase in terms of integration capacity of transistors on integrated circuits has demanded great and constant evolution in the design methodology and practical implementation of embedded electronic systems. Such capacity of integration resulted in the sprouting of systems-on-chips (SoCs). The design of such systems, more complex than their predecessors, significantly changes the traditional flow in the conception of systems, bringing up strategies such like reuse, platform based design, as well as modeling and simulation in different abstraction levels. One of the different abstraction levels under study is the analytical one, where the systems are shaped through abstract representations. The adoption of analytical models presents advantages, such as high speed of execution (allowing a great number of analyses of different models) and easiness for alteration. However, due to their distant representation models, in terms of abstraction, from real implementations, they cannot offer accurate prognostics on several design metrics. Therefore, it is necessary the investigation on methodologies aiming to the enhancement of such models in terms of accuracy and fidelity. The present work shows a methodology of analytical modeling for evaluation of system-on-chip performance guided to the application of network processors of packages. The methodology of Network Calculus, to be implemented in the initial steps of of system-on-chip´s design cycle, contributes to reduce the design space exploration. It deals with the building of analytical equations for abstract representations of workloads and also the processing capacity of resources, aiming at to get most pessimistic and most optimistic prognostics of parameters such like latency, buffer requirements and the system utilization, described in abstract way through graphs.
44

Capteur acoustique sphérique autonome : étude du dispositif de récupération d'énergie vibratoire / Autonomous spherical acoustic sensor : study of the vibratory energy harvesting device

Diab, Daher 07 December 2017 (has links)
Un nouveau capteur acoustique sphérique autonome est proposé. Il est destiné à être immergé dans un milieu liquide ou pâteux pour mesurer certaines propriétés physiques du milieu et récupérer l'énergie vibratoire ambiante pour assurer son autonomie. Le capteur est composé de deux coquilles hémisphériques en plexiglas et d'une bague piézoélectrique en PZ26 fixée entre les deux coquilles. Cette structure peut être utilisée aussi bien en excitateur que capteur. Un modèle de simulation de la récupération d'énergie vibratoire a été développé en considérant seulement deux modes de vibration: mode épaisseur et mode radial. Pour chaque mode, le comportement de l’anneau est décrit par un circuit électromécanique équivalent reliant les ports mécaniques (forces et vitesses) au port électrique (tension et courant). Ce choix est guidé par la possibilité de combiner la partie électromécanique avec l'électronique qui traite l'énergie directement dans un simulateur basé sur Spice. Pour valider cette approche, une simulation par éléments finis a été réalisée et comparée aux résultats produits par le circuit électromécanique. Les fréquences de résonance ont également été vérifiées expérimentalement avec un analyseur d'impédance. Toutes ces vérifications donnent des résultats en très bon accord avec le modèle électromécanique proposé en termes de fréquences de résonance, de tension et de puissance collectées. Enfin, plusieurs validations expérimentales sont présentées avec un prototype de capteur sphérique. Ces validations montrent l’adéquation des prédictions avec les résultats expérimentaux. Finalement, un test du circuit de récupération est effectué en situation réelle. / A new spherical autonomous acoustic sensor is proposed. It is intended to be immersed in a liquid or pasty medium to measure some physical properties of the medium and should harvest ambient energy to ensure its autonomy. The sensor is composed of two Plexiglas half-spherical shells and a PZ26 piezoelectric ring clamped between the two shells. This structure can be used as well as in exciter or sensor. A simulation model of vibrational energy harvesting has been developed considering only two modes of vibration: thickness and radial modes. For each mode, the ring behavior is described by an equivalent electromechanical circuit connecting the mechanical ports (forces and velocities) to the electrical port (voltage and current). This choice is guided by the possibility to combine the electromechanical part with the electronics that process the energy directly in a Spice based simulator. To validate this approach, a finite elements simulation was realized and compared to the electromechanical circuit results. Resonance frequencies were also verified experimentally with an impedance analyzer. All these verifications give results in very good agreement with the proposed electromechanical model, as well as in terms of resonant frequencies, harvested voltage and power. Finally several experimental investigations are presented with a prototype of spherical sensor. These validations show the adequacy of the predictions with the experimental results. Finally, a test of the harvesting circuit is done in real situation.
45

Etude du lien entre la fréquence et les puissances actives pour le dimensionnement d'un microréseau alternatif îloté avec sources d'énergie renouvelables / Study of the link between the frequency and the active power to size an AC stand-alone microgrid with renewable energy sources

Ghanty, Yann 20 December 2018 (has links)
La qualité d’un réseau électrique se mesure notamment par sa résilience, à savoir sa capacité à continuer de fournir, de façon stable, une électricité de qualité malgré les incidents. Cette continuité d’alimentation est notamment assurée par le réglage de la fréquence, ce dernier faisant office de moyen de coopération entre les différentes sources du réseau. Les travaux de cette thèse étudient en profondeur les différentes façons d’assurer ce réglage de la fréquence sur des microréseaux alternatifs îlotés au regard des problématiques nouvelles : intégration croissante de sources d’énergie renouvelables intermittentes et baisse (voire disparition) de l’inertie inhérente aux groupes synchrones tournants. L’objectif principal est de proposer un ensemble de modèles analytiques permettant d’appréhender le comportement dynamique de la fréquence et des puissances actives transitant sur un microréseau, quelle que soit la topologie de ce dernier, afin de constituer une aide au dimensionnement. À cet objectif global s’ajoute un certain nombre de sous-objectifs qui structurent et guident l’ensemble des travaux :- Un objectif pédagogique : les couplages entre l’équilibre des puissances actives et la fréquence sur un réseau alternatif sont clairement explicités, que ces couplages relèvent de la structure et des paramètres physiques du microréseau ou qu’ils soient liés aux lois et paramètres de commande. La lecture des modèles doit ainsi permettre de comprendre analytiquement les différents liens de cause à effet entre les paramètres du système, la fréquence et les puissances,et les spécificités propres à chaque topologie de microréseau.- Un objectif de simplicité et de modularité : les modèles proposés doivent pouvoir être adaptés selon les cas particuliers de topologies, afin que tout lecteur puisse les réutiliser facilement en dehors du cadre de cette étude. Pour ce faire, ces travaux utilisent des modèles mathématiques sous forme de schémas blocs, intégrables sous Matlab.- Enfin, un objectif de modélisation « grand signal » : pour trancher avec l’approche petit signal de beaucoup de modélisations de microréseaux classiques, et pour permettre d’appréhender le comportement du microréseau sur une large plage de déséquilibre de puissance / The quality of an electricity grid is measured by its resilience, namely its ability to continue to provide electricity despite the incidents. This continuity of supply is ensured by the frequency control, acting as a means of cooperation between the different sources of the grid. This thesis examines in depth the different ways to ensure this frequency control on stand-alone microgrids with regard to new issues: increasing integration of intermittent energy sources and decreasing (or disappearing) of the synchronous rotating groups with their inertia. The main objective is to propose a set of analytical models explaining the dynamic behavior of the frequency and the active powers transiting on a microgrid, whatever the topology, in order to constitute an aid to the sizing. To this overall objective is added a number of sub-objectives that structure and guide this work:- An educational objective: the nature of the link between the balance of active powers and the frequency on an AC microgrid is clearly explained, whether this link is based on physical parameters or is related to control laws. The goal is to understand the different links of cause and effect between the paramers of the system, the frequency and the active power and thespecificities to each topology of microgrid. - An objective of simplicity and modularity: the models proposed must be adaptable to particular cases, so that any reader can reuse easily outside the scope of this study. To do this, mathematical models in the form of block diagrams which can be integrated in Matlab are used. - Finally, a "big signal" simulation objective: to decide with the small signal approach of many traditional microgrid models, and to make it possible to understand the behavior of the microgrid over a wide range of power imbalance.
46

CUDA performance analyzer

Dasgupta, Aniruddha 05 April 2011 (has links)
GPGPU Computing using CUDA is rapidly gaining ground today. GPGPU has been brought to the masses through the ease of use of CUDA and ubiquity of graphics cards supporting the same. Although CUDA has a low learning curve for programmers familiar with standard programming languages like C, extracting optimum performance from it, through optimizations and hand tuning is not a trivial task. This is because, in case of GPGPU, an optimization strategy rarely affects the functioning in an isolated manner. Many optimizations affect different aspects for better or worse, establishing a tradeoff situation between them, which needs to be carefully handled to achieve good performance. Thus optimizing an application for CUDA is tough and the performance gain might not be commensurate to the coding effort put in. I propose to simplify the process of optimizing CUDA programs using a CUDA Performance Analyzer. The analyzer is based on analytical modeling of CUDA compatible GPUs. The model characterizes the different aspects of GPU compute unified architecture and can make prediction about expected performance of a CUDA program. It would also give an insight into the performance bottlenecks of the CUDA implementation. This would hint towards, what optimizations need to be applied to improve performance. Based on the model, one would also be able to make a prediction about the performance of the application if the optimizations are applied to the CUDA implementation. This enables a CUDA programmer to test out different optimization strategies without putting in a lot of coding effort.
47

Recrystallization of L-605 cobalt superalloy during hot-working process

Favre, Julien 25 September 2012 (has links) (PDF)
Co-20Cr-15W-10Ni alloy (L-605) is a cobalt-based superalloy combining high strength with keeping high ductility, biocompatible and corrosion resistant. It has been used successfully for heart valves for its chemical inertia, and this alloy is a good candidate for stent elaboration. Control of grain size distribution can lead to significant improvement of mechanical properties: in one hand grain refinement enhance the material strength, and on the other hand large grains provide the ductility necessary to avoid the rupture in use. Therefore, tailoring the grain size distribution is a promising way to adapt the mechanical properties to the targeted applications. The grain size can be properly controlled by dynamic recrystallization during the forging process. Therefore, the comprehension of the recrystallization mechanism and its dependence on forging parameters is a key point of microstructure design approach. The optimal conditions for the occurrence of dynamic recrystallization are determined, and correlation between microstructure evolution and mechanical behavior is investigated. Compression tests are carried out at high-temperature on Thermec-master Z and Gleeble forging devices, followed by gas or water quench. Mechanical behavior of the material at high temperature is analyzed in detail, and innovative methods are proposed to determine the metallurgical mechanisms at stake during the deformation process. Mechanical properties of the material after hot-working and annealing treatments are investigated. The grain growth kinetics of L-605 alloy is determined, and experimental results are compared with the static recrystallization process. Microstructures after hot deformation are evaluated using SEM-EBSD and TEM. Significant grain refinement occurs by dynamic recrystallization for high temperature and low strain rate (T≥1100 ◦ C, strain rate < 0.1s−1), and at high strain rate (strain rate > 10s−1). Dynamic recrystallization is discontinuous and takes place from the grain boundaries, leading to a necklace structure. The nucleation mechanism is most likely to be bulging from grain boundaries and twin boundaries. A new insight of the modeling of dynamic recrystallization taking as a starting point the experimental data is proposed. By combining the results from the mechanical behavior study and microstructure observation, the recrystallization at steady-state is thoroughly analyzed and provides the mobility of grain boundaries. The nucleation criterion for the bulging from grain boundaries is reformulated to a more general expression suitable for any initial grain size. Nucleation frequency can be deduced from experimental data at steady-state through modeling, and is extrapolated to any deformation condition. From this point, a complete analytical model of the dynamic recrystallization is established, and provides a fair prediction on the mechanical behavior and the microstructure evolution during the hot-working process.
48

Modeling and design optimization of electromechanical brake actuator using eddy currents

Karakoc, Kerem 21 September 2012 (has links)
A novel electromechanical brake (EMB) based on the eddy current principle is proposed for application in electrical vehicles. The proposed solution is a feasible replacement for the current conventional hydraulic brake (CHB) systems. Unlike CHBs eddy current brakes (ECBs) use eddy currents and their interaction with an externally applied magnetic field to generate braking torque. Due to their pure electrically controllable and contact free nature, ECBs have multiple advantages over the current CHB systems, such as faster response, reduced weight and number of components, ease of implementing various controllers (e.g., anti-lock braking), and reduced noise levels. However, the torque generated by a typical ECB at low speeds is insufficient to effectively and completely stop a moving vehicle. Therefore, an ECB is commonly used as an assistive brake to the CHB system in heavy vehicles, i.e. trains and trucks In order to overcome this shortcoming, the use of AC magnetic fields is proposed to realize a stand-alone ECB system in which sufficient braking torque can be generated at low speeds. To this end, eddy currents are modeled analytically using the governing Maxwell’s equations with the consideration of time varying field application. The analytical model was validated using finite element analysis. Results show that the braking torque increases with the application of a time varying field. Various forms of time varying fields have been studied. It was found that the frequency-modulated applied field in triangular waveform results in the highest braking torque. Next, the design was optimized to maximize the braking torque and an optimum configuration was obtained using multiple pole projection areas (PPAs). Optimization results show that the braking torque significantly increases with the introduction of additional PPAs to the configuration, and the braking torque generation for an optimum four-PPA ECB configuration exceeds the braking requirements for current passenger vehicles. For control purposes, a dynamic model for a novel stand-alone ECB system using AC fields for automotive applications has been successfully designed and evaluated. Also, a model-based predictive controller has been developed for the optimum ECB configuration. Finally an experimental test-bed has been designed for experimentation of both DC and AC field application on ECB. / Graduate
49

Modelagem de tubos de materiais compósitos laminados considerando efeitos de temperatura e falhas / Modeling of laminated composite tubes considering temperature effects and failure

Santos, Roésio Oliveira 04 November 2016 (has links)
In last decades, there has been a relevant growth in the application of composite materials reinforced by fibers in the several industries, especially the aeronautical, automotive, construction and offshore structures segments. How the composites exhibit relationships stiffness/weight and resistance/high weight, and other interesting features compared with other materials, they have been increasingly used to replace conventional materials. The present work has as objective to develop a study about laminated polymeric composite tubes subjected to thermomechanical loads. The laminae are composed of polymeric matrix involving unidirectional long fiber reinforcement. The walls of the studied tubes present various lamination schemes and different constituent materials. The analyses are set by analytical formulations that permits obtaining the displacements, stresses and strains, as well as verification failures in the laminae. Different empirical and semi-empirical analytical models are used for failure analyses. Effects of thermomechanical loads, such as internal pressure, bending, and temperature changes are considered. The analyzed cases consist of tubes with walls comprised of several layers with different directions of fibers, some including laminae sand impregnated with resin. The results are also compared with other available in the literature. It is verified that the Tsai-Wu criterion provides superior results to the other two failure models used in the work, especially for angles greater than 50°. Moreover, this criterion obtained an inconsistent result in the analysis of the temperature effects for the laminae [+55°/−55°]2. / Fundação de Amparo a Pesquisa do Estado de Alagoas / Nas últimas décadas, houve um grande crescimento na aplicação de materiais compósitos reforçados por fibras em diversos setores, com destaque para os segmentos aeronáutico, automotivo, construção civil e de estruturas offshore. Como os referidos compósitos apresentam relações rigidez/peso e resistência/peso elevadas, além de outras características interessantes, em comparação com outros materiais, eles têm sido cada vez mais utilizados em substituição aos materiais convencionais. O presente trabalho tem como objetivo o desenvolvimento de um estudo sobre tubos de materiais compósitos poliméricos laminados submetidos a cargas termomecânicas. As lâminas são constituídas por uma matriz polimérica envolvendo fibras unidirecionais longas de reforço. As paredes dos tubos estudadas apresentam diferentes esquemas de laminação, podendo ser constituídas por diferentes materiais. As análises são feitas através de formulações analíticas que permitem a obtenção dos deslocamentos, tensões e deformações, assim como a verificação de falhas nas lâminas. Para a análise de falhas são empregados diferentes modelos analíticos empíricos e semiempíricos. Efeitos de cargas termomecânicas, tais como pressão interna, flexão e de variação de temperatura são considerados. Os casos analisados consistem de tubos com paredes constituídas por várias camadas com diferentes direções de fibras, alguns incluindo lâminas de areia impregnada com resina. Os resultados encontrados também são comparados com outros disponíveis na literatura. Verifica-se que o critério de Tsai-Wu fornece resultados superiores aos dos outros dois modelos de falha utilizados no trabalho, principalmente para ângulos superiores a 50°. Além disso, esse critério obteve resultado inconsistente na análise dos efeitos de temperatura para o laminado [+55°/−55°]2.
50

Développement d’un modèle analytique d’interaction sol-structure pour l'étude du comportement mécanique des structures soumises à un mouvement de terrain : influence des déformations de cisaillement et de la plasticité / Development of an analytical model of soil-structure interaction for studying the mechanical behavior of structures due to ground movement : Effect of shear deformations and plasticity

Basmaji, Bakri 15 December 2016 (has links)
Ce travail s'inscrit dans la continuité des travaux de recherche menés au laboratoire Géoressources (Ecole des Mines de Nancy) et à l'INERIS depuis plusieurs années. Il concerne l’évaluation de la vulnérabilité des ouvrages situés dans des zones de mouvement de terrains d’origine naturelle ou anthropique. L’objectif de la thèse est de développer un modèle analytique permettant l’évaluation du tassement différentiel d’un ouvrage soumis à un mouvement de terrain et de calculer le taux de transmission de ces mouvements en fonction de la rigidité relative de l’ouvrage. Le modèle d’interaction sol-structure développé, tient compte de l’influence des contraintes de cisaillement dans le bâti et le terrain et d’un comportement poste-rupture du sol grâce à l’introduction d’une limite de plasticité. Le sol a été modélisé par les éléments de Pasternak afin de prendre en compte l'influence des déformations de cisaillement dans le sol, alors que le bâtiment est modélisé par la poutre d'Euler-Bernoulli et par la poutre de Timoshenko. L’existence potentielle d’un vide (décollement) sous le bâtiment a également été prise en compte dans le modèle analytique développé. Le taux de transmission des mouvements en champ libre du terrain au bâtiment a été calculé et présenté en fonction de la rigidité relative en flexion du bâtiment par rapport au terrain. Pour valider le développement entrepris, les résultats du modèle analytique ont été comparés aux résultats de modèles existants, analytiques, numériques et expérimentaux développés principalement par l'Université de Cambridge. Les résultats obtenus sont très satisfaisants et permettant de confirmer la robustesse du modèle analytique développé / This work is a continuation of the research work conducted in the Géoressources Laboratory and INERIS since several years. It concerns the assessment of the vulnerability of masonry structures influenced by natural or induced ground movements. The origins of the movement are may be, mining subsidence, tunneling, and shrinkage-swelling of clayed ground. The objective of the thesis is to develop an analytical model to evaluate the differential settlement of a structure in relation to the free field ground movement and given a set of phenomena: soil-structure interaction, influence of shear deformations in the structure and the ground, influence of non- linearities induced by the ground yielding. The soil was modeled by Pasternak elements to take into account the influence of shear deformations in the soil, while the building is modeled by the Euler-Bernoulli beam and by the beam of Timoshenko. The possibility of having a gap under the building was also taken into account. The deflection transmission ratio is then calculated and plotted according to are lative stiffness ratio which depend on both the structure and the soil stiffness A numerical model is also developed and results are compared with those of the analytical model. Other results of several numerical and experimental models principally developed at the University of Cambridge are also used for this comparison. Results show significant consistence between all these results. This demonstrates the significance of the analytical soil-structure model developed in this thesis

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