Nesta tese, apresenta-se a análise numérica e experimental do comportamento dinâmico não linear de um pórtico excitado por uma fonte não ideal - um motor elétrico de corrente contínua desbalanceado - como exemplo dessa classe de problemas. Elabora-se um modelo matemático com quatro graus de liberdade: dois relacionados com o deslocamento horizontal e vertical do ponto de apoio da máquina e dois com os parâmetros de funcionamento do motor elétrico. Adota-se a formulação Lagrangeana para gerar as equações de movimento contendo termos não lineares até ordem cúbica. A solução numérica é obtida através do método de Runge-Kutta com passo adaptativo. Ensaios dinâmicos e estáticos foram realizados com o motor e com o sistema completo, com vistas a validar o modelo matemático. Um sistema de medição digital armazenou todos os dados obtidos em arquivos de fácil leitura pelos programas atualmente disponíveis. Filmagens de alta velocidade e fotografia estroboscópica registraram movimentos típicos relacionados com comportamentos não lineares. Os resultados numéricos e experimentais mostram boa correlação entre si, além de apresentarem alguns dos fenômenos associados ao se forçar uma estrutura a passar por uma de suas ressonâncias excitando-a com um dispositivo com potência limitada, como o efeito Sommerfeld. Outros fenômenos, devido ao comportamento geometricamente não linear da estrutura, são também detectados, tais como saturação modal e transferência de energia. / Numerical and experimental analysis of the nonlinear dynamics of a portal frame excited by a non-ideal source - an unbalanced direct current motor - is presented in this thesis as an example of this class of problems. A four degree of freedom model is elaborated: two of them related to the horizontal and vertical structural displacements and two others to the functioning parameters of the motor. A Lagrangian approach for deducing the equations of motion, up to cubic non-linear terms is followed. The numerical solution is obtained through Runge-Kutta algorithm with adaptive step. Static and dynamic tests were performed with the motor and with the complete system, in order to validate the mathematical model. A digital acquisition system recorded all data in computer files, ready to be read by available commercial programs. High speed filming and stroboscopic photography were used to register typical movements related to nonlinear behavior. Numerical and mathematical results show good correlation, as well as present some phenomena related to passage through resonance with limited power excitation such as the Sommerfeld effect. Some other phenomena, related to the nonlinear behavior of the structure are also detected, as modal saturation and energy transference.

Inicialmente, apresentam-se características de dispositivos eletrônicos conhecidos como PLLs (phase-locked loops). PLLs são amplamente empregados para se extrair sinais de tempo em canais de comunicação e em aplicações nas quais se deseja controle automático de freqüência. O objeto principal é estudar PLLs analógicos descritos por uma equação diferencial ordinária de terceira ordem. Assim, deduzem-se condições de estabilidade assintótica e identifica-se um regime de caos conservativo, que ocorre sob certas combinações de valores de parâmetros. Três métodos de controle não-linear/caótico são então apresentados e aplicados. Os métodos são os seguintes: o Método de Pyragas via realimentação de variável de estado; o Método de Pyragas com atraso temporal na realimentação; e o Método de Sinha, o qual efetua o controle perturbando um parâmetro do sistema. Simulações numéricas são levadas a cabo a fim de ilustrar o comportamento dinâmico do sistema quando sujeito à ação desses métodos. Este trabalho termina com um estudo de uma rede formada por uma cadeia de PLLs. Condições para soluções síncronas, periódicas e caóticas (dissipativas e conservativas) são deduzidas para tal rede. / Firstly, features of electronic devices known as PLLs (Phase-Locked Loops) are presented. PLLs are widely employed to extract time signals in communication channels and in applications where automatic control of frequency is desired. The main goal is to study analog PLLs described by a third-order nonlinear ordinary differential equation. Thus, conditions for asymptotic stability are derived and a regime of conservative chaos occurring under certain combinations of parameter values is identified. Then, three methods of control of nonlinear/ chaotic dynamics are presented and applied. The methods are the following: the Pyragas method via feedback of state variable; the Pyragas method with time delay in the feedback; and the Sinhas method, which performs the control by disturbing a parameter of the system. Numerical simulations are accomplished in order to illustrate the dynamical behavior of the system when subjected to the action of these methods. This work ends with a study of a single-chain PLL network. Conditions for synchronous, periodic and chaotic (dissipative and conservative) solutions are derived for such a network.

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Enfermagem, Escola de Enfermagem, 2012. / Submitted by eloisa silva (eloisa1_silva@yahoo.com.br) on 2013-01-15T16:04:05Z No. of bitstreams: 1 diessica.pdf: 1723660 bytes, checksum: c48118a1f4987ce6689a9f814d9fc6a9 (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2013-01-23T19:26:34Z (GMT) No. of bitstreams: 1 diessica.pdf: 1723660 bytes, checksum: c48118a1f4987ce6689a9f814d9fc6a9 (MD5) / Made available in DSpace on 2013-01-23T19:26:34Z (GMT). No. of bitstreams: 1 diessica.pdf: 1723660 bytes, checksum: c48118a1f4987ce6689a9f814d9fc6a9 (MD5) Previous issue date: 2012 / Este estudo objetivou conhecer o significado de cuidado de enfermagem para enfermeiros docentes e conhecer o que diferencia o cuidado do enfermeiro do cuidado dos demais profissionais, na perspectiva da complexidade. Trata-se de estudo de abordagem qualitativa, do tipo exploratório e descritivo, que possuí como fio condutor a complexidade de Edgar Morin. Os participantes do estudo foram sete enfermeiros docentes do curso de graduação em Enfermagem do Centro Universitário Franciscano, localizado na região central do Rio Grande do Sul, os quais participam do Grupo de Estudos e Pesquisa em Empreendedorismo Social da Enfermagem e Saúde da referida instituição. A coleta de dados, realizada no mês de novembro de 2011, baseou-se na técnica de grupo focal, a partir de três encontros, nos quais foram desenvolvidos momentos de sensibilização, de leitura (textos selecionados), de reflexão e discussão conjunta e de fechamentos/acordos. Cada encontro foi norteado por temas específicos. No primeiro encontro foi apresentado um texto sobre a Complexidade, para maior aproximação com o tema, seguido de uma discussão a respeito do cuidado de enfermagem. No segundo encontro foram apresentados e discutidos os sete princípios da Complexidade de Edgar Morin. E, no terceiro encontro discutiu-se acerca do cuidado do enfermeiro e suas especificidades em relação ao cuidado dos demais profissionais. Para a análise dos dados utilizou-se a análise textual discursiva, da qual emergiram duas grandes categorias: cuidado de enfermagem complexo como construção singular; divergências e convergências entre o cuidado do enfermeiro e o cuidado dos demais profissionais, seguidas de suas respectivas subcategorias. Evidenciou-se, que o cuidado de enfermagem complexo como construção singular vai além de um cuidado técnico-prescritivo, pontual e linear e que o enfermeiro desenvolve um cuidado ampliado, diferentemente do cuidado dos demais profissionais, além de ser ele o articulador e integrador do cuidado. Conclui-se, que o cuidado de enfermagem não pode ser concebido como ação reducionista, mas como construção singular, que envolve interações, reflexões e autoconhecimento, além do enfermeiro precisar ser capaz de desenvolver um cuidado ampliado, contextualizado e focado nas necessidades dos seres humanos. / This study aimed at knowing what nursing care means to nurse educators and what differentiates nurse’s care from other professionals’ care, in the perspective of complexity. This is a qualitative, exploratory and descriptive study, which has Edgar Morin’s complexity paradigm as its guiding principle. The participants of the study were seven nurse educators from the undergraduate course in Nursing of Franciscan University Center, located in central Rio Grande do Sul. They are members of the Group of Study and Research in Social Entrepreneurship of Nursing and Health of the aforementioned institution. Data collection, carried out in November 2011, was based in the focus group technique. It was accomplished in three meetings, which created moments for awareness, reading (of selected texts), group reflection and discussion, and conclusions/agreements. Each meeting was guided by particular topics. In the first meeting a text about Complexity was introduced, for a better awareness of the topic, and followed by a discussion about nursing care. In the second meeting the seven principles of Edgar Morin’s Complexity Theory were introduced and discussed. Finally, the third meeting discussed the nurse’s care and its specificities in relation to other professionals’ care. Discursive text analysis was used for data analysis, and two big categories emerged: complex nursing care as a unique construction, and divergences and convergences between nurse’s care and other professional’s care, followed by their respective sub-categories. Results evinced that nursing care as unique construction goes beyond a technical-prescriptive, punctual and linear care. It was also made clear that nurses develop an expanded care that is different from the punctual care of other professionals – moreover, nurses are the articulators and integrators of this care. The study concludes that nursing care cannot be conceived as a reductionist action, but as a unique construction, which involves interactions, reflections and self-knowledge, besides the fact that nurses need to be capable of developing an expanded care which is contextualized and focused on the needs of human beings. / Este estudio ha objetivado conocer el significado del cuidado de enfermería para enfermeros docentes y conocer lo que diferencia el cuidado del enfermero del cuidado de los demás profesionales, en la perspectiva de la complejidad. Se trata de un estudio cualitativo, exploratorio y descriptivo, que tiene como guía la complejidad de Edgar Morin. Los participantes del estudio fueron siete enfermeros docentes del curso de graduación en Enfermería del Centro Universitario Franciscano, ubicado en la región central del Rio Grande do Sul, los cuales participan del grupo de estudio e investigación en Emprendimiento Social de la Enfermería y Salud de la institución. La recolecta de los datos, fue realizada en el mes de noviembre de 2011, se basó en la técnica de grupos focales, a partir de tres encuentros, en los cuales fueron desarrollados momentos de sensibilización, de lectura (textos seleccionados), de reflexión y debate y de cierres/acuerdos. Cada encuentro fue basado por temas específicos. En el primer encuentro fue presentado un texto sobre la complejidad, para mayor aproximación con el tema, seguido de una discusión sobre el cuidado en enfermería. En la según encuentro fueron presentados y discutidos los siete principios de la complejidad de Edgar Morin. Y en el tercer encuentro se discutió sobre el cuidado del enfermero y sus especificidades en relación al cuidado de los demás profesionales. Para el análisis de los datos se utilizó el análisis textual discursivo, donde surgieron dos grandes categorías: cuidado de enfermería complejo como construcción singular; divergencias y convergencias entre el cuidado del enfermero y el cuidado de los demás profesionales, seguidas de sus respectivas subcategorías. Se evidenció, que el cuidado de enfermería complejo como construcción singular va allende un cuidado técnico prescriptivo, puntual y lineal y que el enfermero desarrolla un cuidado amplio, distinto del cuidado de los demás profesionales, siendo el enfermero el articulador e integrador del cuidado. Se concluye que el cuidado de enfermería no puede ser concebido como acción reduccionista, más como construcción singular, que implica interacciones, reflexiones y conocimiento propio, allende el enfermero tener capacidad de desarrollar un cuidado amplio, contextualizado y centrado en las necesidades de los seres humanos.

Esta tese trata o escoamento ao redor de um cilindro logo após a sua primeira instabilidade, dentro do seu regime bidimensional periódico. A abordagem é principalmente teórica, passa por experimentos e culmina em uma importante parte numérica que complementa a teoria com evidências e ilustrações. As principais contribuições são a análise sobre a composição modal da solução dentro do regime periódico e o método desenvolvido para identificar autovetores de uma linearização da equação de Navier-Stokes presentes em uma dada solução. As bases compostas pelos autovetores identificados servem para a projeção da equação de Navier-Stokes e dão a essência dos modelos reduzidos deste estudo. A aplicação numérica apresentada para Re = 60 traz duas iterações do processo, com duas bases de autovetores de dimensões 12 e 24. Os modelos reduzidos são numericamente estáveis e a sua integração apresenta custo várias ordens mais baixo que o da simulação numérica completa. As séries temporais das coordenadas e as bases de autovetores possibilitam a recomposição do escoamento e a sua comparação com a simulação numérica de referência. A análise de aderência foi baseada nas médias temporais, nos valores de Strouhal e na estrutura dos harmônicos. Ambos modelos reduzidos têm correspondência próxima com o comportamento assintótico do escoamento e a tendência convergente das iterações é clara. As simetrias espaciais e temporais dos harmônicos são facilmente identificadas na estrutura dos modelos, de forma que as bases construídas podem ser entendidas como conjuntos de estruturas coerentes do fenômeno. / This thesis concerns the flow past a cylinder just after its first bifurcation, within its two-dimensional periodic regime. The approach is mainly theoretical, goes through experiments and is concluded by an important numerical part which complements the theory with evidences and illustrations. The main contributions are the analysis concerning the modal composition of the solution within the periodic regime and a method to identify eigenvectors of some linearizaton of the Navier-Stokes equation participating on a given solution. The bases spanned by the identified eigenvectors are employed in the projection of the Navier-Stokes equation and are central to the reduced models of this study. The numerical results for Re = 60 present two iterations of the process, with two bases of dimensions 12 e 24. The reduced models are numerically stable and their integration is many orders less costly than that of the full simulation. The time series of the modal coordinates and the eigenvectors bases allow the recomposition of the flow and its comparison with the full simulation results. The convergence analysis was based on the time averages, the Strouhal number values and the harmonic structure. Both reduced models have close correspondence with the asymptotic behavior of the flow and the convergent trend of the iterations is clear. The space and time symmetries of the harmonics have a simple representation within the structure of the models, therefore the identified bases can be understood as sets of coherent structures of the phenomenon.

Dans cette Thèse, la conception robuste avec un modèle incertain d'un système électromécanique avec vibro-impact est fait. Le système électromécanique est constitué d'un chariot, dont le mouvement est excité par un moteur à courant continu et un marteau embarqué dans ce chariot. Le marteau est relié au chariot par un ressort non linéaire et par un amortisseur linéaire, de façon qu'un mouvement relatif existe entre eux. Une barrière flexible linéaire, placé à l'extérieur du chariot limite les mouvements de marteau. En raison du mouvement relatif entre le marteau et la barrière, impacts peuvent se produire entre ces deux éléments. Le modèle du système développé prend en compte l'influence du courant continu moteur dans le comportement dynamique du système. Certains paramètres du système sont incertains, tels comme les coefficients de rigidité et d'amortissement de la barrière flexible. L'objectif de la Thèse est de réaliser une optimisation de ce système électromécanique par rapport aux paramètres de conception afin de maximiser l'impact puissance sous la contrainte que la puissance électrique consommée par le moteur à courant continu est inférieure à une valeur maximale. Pour choisir les paramètres de conception dans le problème d'optimisation, une analyse de sensibilité a été réalisée afin de définir les paramètres du système les plus sensibles. L'optimisation est formulée dans le cadre de la conception robuste en raison de la présence d'incertitudes dans le modèle. Les lois de probabilités liées aux variables aléatoires du problème sont construites en utilisant le Principe du Maximum l'Entropie et les statistiques de la réponse stochastique du système sont calculées en utilisant la méthode de Monte Carlo. L'ensemble d'équations non linéaires sont présentés, et un solveur temporel adapté est développé. Le problème d'optimisation non linéaire stochastique est résolu pour différents niveaux d'incertitudes, et aussi pour le cas déterministe. Les résultats sont différents, ce qui montre l'importance de la modélisation stochastique / In this Thesis, the robust design with an uncertain model of a vibro-impact electromechanical system is done. The electromechanical system is composed of a cart, whose motion is excited by a DC motor (motor with continuous current), and an embarked hammer into this cart. The hammer is connected to the cart by a nonlinear spring component and by a linear damper, so that a relative motion exists between them. A linear flexible barrier, placed outside of the cart, constrains the hammer movements. Due to the relative movement between the hammer and the barrier, impacts can occur between these two elements. The developed model of the system takes into account the influence of the DC motor in the dynamic behavior of the system. Some system parameters are uncertain, such as the stiffness and the damping coefficients of the flexible barrier. The objective of the Thesis is to perform an optimization of this electromechanical system with respect to design parameters in order to maximize the impact power under the constraint that the electric power consumed by the DC motor is lower than a maximum value. To chose the design parameters in the optimization problem, an sensitivity analysis was performed in order to define the most sensitive system parameters. The optimization is formulated in the framework of robust design due to the presence of uncertainties in the model. The probability distributions of random variables are constructed using the Maximum Entropy Principle and statistics of the stochastic response of the system are computed using the Monte Carlo method. The set of nonlinear equations are presented, and an adapted time domain solver is developed. The stochastic nonlinear constrained design optimization problem is solved for different levels of uncertainties, and also for the deterministic case. The results are different and this show the importance of the stochastic modeling

Les rotors sont excités non seulement par le balourd tournant mais aussi par les différents mouvements de leur support : turbocompresseurs de véhicules, turbomoteurs aéronautiques, pompes à vide portées en sont des exemples industriels. Ainsi la conception de rotors robustes capables de bien fonctionner sous de telles conditions (excitations extrêmes) est nécessaire pour éviter des instabilités, source de défaillance catastrophique. Le présent travail a pour objectif de prévoir le comportement dynamique d’un rotor embarqué monté sur des paliers rigides ou élastiques hydrodynamiques et soumis à des excitations du support rigide. Les énergies cinétiques et de déformation ainsi que le travail virtuel des composants d’un rotor flexible tournant sont calculés. Le modèle proposé de rotor embarqué est basé sur les éléments finis de poutre de TIMOSHENKO. Il contient les effets relatifs à l’inertie de rotation des sections droites, à l’inertie gyroscopique, à la déformation de cisaillement d’arbre et à la dissymétrie géométrique de l’arbre et/ou du disque rigide et considère six types de mouvements déterministes (rotations et translations) du support. Suivant le type d’analyse utilisé pour le palier, les forces de rappel hydrodynamiques agissant sur l’arbre et calculées avec l’équation de REYNOLDS sont linéaires/non linéaires. L’utilisation des équations de LAGRANGE fournit les équations différentielles linéaires/non linéaires du mouvement du rotor embarqué en flexion par rapport au support mobile supposé rigide, qui représente un système de coordonnées non inertiel. Les équations du mouvement contiennent des termes paramétriques périodiques en raison de la dissymétrie géométrique du rotor et des termes paramétrique variables dans le temps en raison des rotations du support. Ces termes paramétriques sont considérés comme des sources d’excitation intérieure et conduisent à une instabilité dynamique latérale. Dans les applications numériques proposées, trois configurations de rotor embarqué sont analysées. Tout d’abord, un rotor symétrique monté sur des paliers rigides est soumis à un balourd combiné avec des mouvements de rotation constante et de translation sinusoïdale du support. Ensuite, un rotor avec une dissymétrie géométrique du disque monté sur des paliers rigides est excité par l’effet de balourd et par des mouvements combinés de rotation constante et de translation sinusoïdale du support. Enfin, un rotor symétrique monté sur des paliers hydrodynamiques est soumis au balourd et aux excitations sinusoïdales de rotation ou de translation du support. / Rotors are excited not only by the rotating mass unbalance but also by the different motions of their support: vehicle turbochargers, aircraft turbo-engines, carried vacuum pumps, are different industrial applications. Thus the design of robust rotors able to run well under such conditions (extreme excitations) and to avoid catastrophic failure is required. The present work aims to predict the dynamic behavior of an on-board rotor mounted on rigid or elastic hydrodynamic journal bearings and subjected to rigid support excitations. The kinetic and strain energies as well as the virtual work of the rotating flexible rotor components are computed. The proposed on-board rotor model is based on TIMOSHENKO beam finite elements. It includes the effects relative to the rotating inertia, the gyroscopic inertia, the shear deformation of shaft as well as the geometric asymmetry of shaft and/or rigid disk and considers six types of deterministic motions (rotations and translations) of the support. Depending on the type of analysis used for the bearing, the restoring fluid film forces acting on the shaft and computed with the REYNOLDS equation are linear/non-linear. The use of LAGRANGE’s equations yields the linear/non-linear differential equations of vibratory motion of the on-board rotor in bending with respect to the moving rigid support which represents a non-inertial reference frame. The equations of motion contain periodic parametric coefficients because of the geometric asymmetry of the rotor and time-varying parametric coefficients because of the support rotations. These parametric coefficients are considered as sources of internal excitation and can lead to lateral dynamic instability. In the proposed numerical application examples, three rotor configurations are studied. Firstly, a symmetric rotor mounted on rigid bearings is subjected to rotating mass unbalance combined with constant rotation and sinusoidal translation of the support. Secondly, a rotor with geometric asymmetry due to the disk mounted on rigid bearings is excited by the mass unbalance effect and by the combination of a constant rotation and a sinusoidal translation of the support. Thirdly, a symmetric rotor mounted on linearized/non-linear hydrodynamic bearings is subjected to the excitation due to the mass unbalance and to the sinusoidal rotational or translational excitations of the support.

Afin d’accomplir les promesses des récupérateurs d’énergie vibratoire (VEHs) qui s’imposent comme unealternative majeure pour garantir l’autonomie des capteurs pour la surveillance, leurs performances en termes debande passante et puissance récupérable doivent être améliorées. Dans cette thèse, à la différence des VEHs classiqueslinéaires et multimodales ou non-linéaires et mono-fréquence, on propose une approche de récupérationd’énergie basée sur des réseaux d’aimants couplés en lévitation ou élastiquement guidés combinant les avantagesdes non-linéarités et des interactions modales. Une étude bibliographique sur les récupérateurs d’énergie vibratoireest effectuée. En particulier, les inconvénients des récupérateurs linéaires et les techniques de réglage de fréquencesont présentées. De plus, les méthodes non-linéaires sont présentées pour définir une procédure de résolution permettantl’étude de la dynamique des récupérateurs non-linéaires. Les équations du mouvement qui contiennentla non-linéarité magnétique, la non-linéarité géométrique et l’amortissement électromagnétique sont résolus enutilisant la méthode de la balance harmonique couplée avec la méthode asymptotique numérique. Une méthodologied’optimisation multi-objectif basée sur l’algorithme Non Sorting Genetic Algorithm est appliquée afin decalculer les solutions optimales pour maximiser les performances du récupérateur d’énergie. Grâce au couplagenon-linéaire et aux interactions modales, pour le cas des trois aimants couplés, l’approche proposée permet la récupérationde l’énergie vibratoire dans la gamme fréquentielle 4;6 - 14;5 Hz, avec une bande passante d’environ190 % et une puissance normalisée de 20,2 mWcm-3g-2. / In order to accomplish the promises of vibration energy harvesters (VEHs) as a major alternative to powersensors, their performances in terms of frequency bandwidth and harvested power have to be improved. In thisthesis, unlike classical VEHs either linear and multimodal or nonlinear and mono-frequency, we propose a vibrationenergy harvesting approach based on arrays of coupled levitated or elastically guided magnets combining thebenefits of nonlinearities and modal interactions.A review of VEHs is carried out. Particularly, the design issues of linear harvesters are addressed and frequencytuning techniques are presented. A review of nonlinear methods is also presented in order to define a solving procedureenabling the investigation of the dynamics of nonlinear VEHs. The equations of motion which include themagnetic nonlinearity, the geometric nonlinearity and the electromagnetic damping are solved using the harmonicbalance method coupled with the asymptotic numerical method. A multi-objective optimization procedure isintroduced and performed using a non-dominated sorting genetic algorithm for the cases of small magnet arraysin order to select the optimal solutions in term of performances by bringing the eigenmodes close to each other interms of frequencies and amplitudes. Thanks to the nonlinear coupling and the modal interactions even for onlythree coupled magnets, the proposed method enable harvesting the vibration energy in the operating frequencyrange of 4.6–14.5 Hz, with a bandwidth of 190 % and a normalized power of 20:2mWcm-3g-2.

Dans les générateurs de vapeurs (GV), les tubes du circuit primaire sont sujets aux chocs et aux forces de couplage auto-excitatrices nommées forces fluides élastiques.Il est crucial, lors du dimensionnement des GV, de maîtriser la dynamique de ces tubes, ainsi que d'estimer au mieux les efforts mécaniques auxquels ils sont soumis.En effet, cela permet aux ingénieurs d'optimiser la durée de vie des installations et d’augmenter le rendement des centrales électriques.Le but de la présente thèse est de trouver une technique d'essai hybride, basée sur le contrôle actif des vibrations, pour reproduire la contribution modale des forces de couplage sur un tube. En effet, les expériences en milieu réel, dans les conditions que l'on trouve dans les GV, sont hors de prix et très difficiles à reproduire. Dans ces travaux de recherche, une structure de test interagit avec un modèle numérique, qui modélise le fluide, à travers un système de contrôle actif en temps réel. Dans un premier temps les efforts mécaniques appliqués sur le tube sont caractérisés, puis un système de contrôle, constitué de transducteurs et de la carte de contrôle, est conçu pour générer les forces de couplage sur le tube, en prenant en considération les non-linéarités dues aux impacts. / In steam generators, the primary loop tubes are subjected to fluid-elastic couplingforces and impacts. Understanding the dynamic of these tubes is crucial when designingsteam generators. Mastering coupling and impacts forces would allow engineers toimprove the design of structure components and would optimize the tube lifetime, whileimproving the overall performances of power plant.The aim of the current research is to provide a hybrid test technique reproducingthe modal coupling forces on a tube, since experiments on fluid are expensive anddifficult to set up. In this work, the experimental structure interacts with a numericalmodel (which models the fluid-elastic coupling forces) via a real time controller and aset of transducers. First, we characterize the coupling and impact forces, and then, anactive vibration control approach is set up to reproduce the modal contribution of fluidelasticforces on the tube, taking in consideration the non-linearities due to the impacts.

Prospection de pétrole utilise un équipement appelé tube de forage pour forer le sol jusqu'au le niveau du réservoir. Cet équipement est une longue colonne rotative, composée par une série de tiges de forage interconnectées et les équipements auxiliaires. La dynamique de cette colonne est très complexe parce que dans des conditions opérationnelles normales, elle est soumise à des vibrations longitudinales, latérales et de torsion, qui présentent un couplage non linéaire. En outre, cette structure est soumise à effets de frottement et à des chocs dûs aux contacts mécaniques entre les paires tête de forage/sol et tube de forage/sol. Ce travail présente un modèle mécanique-mathématique pour analyser un tube de forage en configuration horizontale. Ce modèle utilise la théorie des poutres qui utilise l'inertie de rotation, la déformation de cisaillement et le couplage non linéaire entre les trois mécanismes de vibration. Les équations du modèle sont discrétisées par la méthode des éléments finis. Les incertitudes des paramètres du modèle d'interaction tête de forage/sol sont prises en compte par l'approche probabiliste paramétrique, et les distributions de probabilité des paramètres aléatoires sont construits par le principe du maximum d'entropie. Des simulations numériques sont réalisées afin de caractériser le comportement dynamique non linéaire de la structure, et en particulier, de l'outil de forage. Des phénomènes dynamiques non linéaires par nature, comme le slick-slip et le bit-bounce, sont observés dans les simulations, ainsi que les chocs. Une analyse spectrale montre étonnamment que les phénomènes slick-slip et bit-bounce résultent du mécanisme de vibration latérale, et ce phénomène de choc vient de la vibration de torsion. Cherchant à améliorer l'efficacité de l'opération de forage, un problème d'optimisation qui cherche à maximiser la vitesse de pénétration de la colonne dans le sol, sur ses limites structurelles, est proposé et résolu / Oil prospecting uses an equipment called drillstring to drill the soil until the reservoir level. This equipment is a long column under rotation, composed by a sequence of connected drill-pipes and auxiliary equipment. The dynamics of this column is very complex because, under normal operational conditions, it is subjected to longitudinal, lateral, and torsional vibrations, which presents a nonlinear coupling. Also, this structure is subjected to friction and shocks effects due to the mechanical contacts between the pairs drill-bit/soil and drill-pipes/borehole. This work presents a mechanical-mathematical model to analyze a drillstring in horizontal configuration. This model uses a beam theory which accounts rotatory inertia, shear deformation, and the nonlinear coupling between three mechanisms of vibration. The model equations are discretized using the finite element method. The uncertainties in bit-rock interaction model parameters are taken into account through a parametric probabilistic approach, and the random parameters probability distributions are constructed by means of maximum entropy principle. Numerical simulations are conducted in order to characterize the nonlinear dynamic behavior of the structure, specially, the drill-bit. Dynamical phenomena inherently nonlinear, such as slick-slip and bit-bounce, are observed in the simulations, as well as shocks. A spectral analysis shows, surprisingly, that slick-slip and bit-bounce phenomena result from the lateral vibration mechanism, and that shock phenomena comes from the torsional vibration. Seeking to increase the efficiency of the drilling process, an optimization problem that aims to maximize the rate of penetration of the column into the soil, respecting its structural limits, is proposed and solved

[pt] O controle passivo de vibrações em edifícios usando absorsores pendulares tem sido bastante estudado na literatura técnica e usado na pratica em edifícios altos como o Taipei-101 em Taiwan. Como a frequência do pêndulo depende apenas do seu comprimento e da aceleração da gravidade, para sintonizar a frequência do pêndulo com a do edifício, tem-se como única variável de projeto o comprimento do pêndulo. Entretanto, em muitos casos, o comprimento necessário e o espaço requerido não se coadunam com o projeto. Nestes casos pode-se substituir o pêndulo clássico por um sistema pendular equivalente composto por uma massa que se movimenta sobre uma superfície curva, permitindo maior flexibilidade no projeto do absorsor, já que o comprimento do pêndulo torna-se irrelevante e a forma da superfície curva pode ser otimizada. Em virtude do movimento da massa sobre a superfície curva, novas forças de inércia e amortecimento não encontradas no pêndulo clássico podem aparecer. No presente trabalho um sistema pendular composto de uma massa que se desloca através de suportes rolantes sobre uma superfície curva é proposto para controle das oscilações de estruturas sob excitação de base. Este sistema pendular tem a vantagem de poder ser usado tanto como um amortecedor pendular de massa sintonizada (APMS) quanto como isolador de base pendular (IBP). Como o sistema pendular pode, em certos casos, apresentar grandes rotações, barreiras que limitam o movimento são propostas, gerando forças de impacto cuja eficiência no controle de vibrações é aqui investigada. / [en] The passive vibration control of buildings using pendulum absorber has been extensively studied in the technical literature and used in high buildings such as the Taipei-101 in Taiwan. Since the frequency of the pendulum depends only on its length and the acceleration of gravity, to tune the frequency of the pendulum to that of the building, its length is the sole design variable. However, in many cases, the pendulum length and the space required for its installation are not consistent with the design. In these cases one can replace the classic pendulum with an equivalent pendulum system comprising a mass that moves on a curved surface, allowing greater flexibility in the absorber design as the length of pendulum becomes irrelevant and the shape of the curved surface can be optimized. Because of the mass movement on the curved surface, new inertia and stiffness forces not found in the classic pendulum may appear. In the present work a pendulum system comprising a mass that moves through rolling bearings on a curved surface is proposed for control of the oscillations of structures under base excitation. This pendulum system has the advantage of being used both as a pendulum tuned mass damper (APMS) and as a base isolation pendulum system (IBP). As the pendulum system can, in certain cases, display large rotations, barriers which limit its movement are proposed, generating impact forces whose efficiency in vibration control is here investigated.