Este trabalho consiste no desenvolvimento de uma metodologia de projeto ótimo de estruturas ativamente controladas (inteligentes), com o objetivo de suprimir as vibrações induzidas por perturbações externas. O projeto é realizado simultaneamente para a topologia estrutural e a localização de atuadores. O problema de otimização topológica é formulado para três fases materiais (dois materiais sólidos e vazio),com dois grupos de variáveis de projeto. Um material não piezelétrico elástico isotrópico forma a parte puramente estrutural, enquanto um material piezelétrico compõe a parte ativa. Uma vez que não há método eficiente para tratar as variáveis de projeto estruturais e de controle em um mesmo ambiente de otimização, este trabalho propõe uma abordagem de solução aninhada. Nesta solução, o posicionamento dos atuadores e a síntese do sistema controlador são considerados em um laco de projeto paralelo ao processo de otimização que lida com a topologia estrutural. O laço de otimização principal está relacionado `as variáveis de projeto estruturais, ou seja, ´e calculado onde deve haver material sólido e onde deve haver espaços vazios, através de um problema de minimização de flexibilidade. A localização de atuadores ´e determinada por uma otimização baseada em uma lei de controle que define onde o material deve ter propriedades piezelétricas, através da maximização de uma medida de controlabilidade. Os exemplos numéricos mostram que a abordagem utilizada neste trabalho pode produzir uma topologia estrutural bem definida com uma boa colocação para os atuadores. Além disso, as topologias ótimas encontradas são capazes de melhorar o amortecimento ativo da estrutura. / This work develops an optimal design methodology for actively controlled structures, aiming to suppress vibrations induced by external disturbances. Design is conducted simultaneously for the structural topology and actuator placement. A topology optimization problem is formulated for three material phases (two solid materials and void) with two design variables groups. A non-piezoelectric elastic isotropic material forms the structural only part of the design, while a piezoelectric material composes the active part. Since there is no efficient method to treat structural and control design variables in the same optimization framework, this work proposes a nested solution approach, where the actuator locations and controller syntheses are regarded as a parallel design to the main optimization process dealing with the structural topology. The main optimization loop designs the structural variables, i.e., it is decided where there should be solid material and where there should be voids, through a minimum compliance design problem. The actuators are placed by considering a control law optimization that defines where the material should have piezoelectric properties, through the maximization of a measure of controllability. Numerical examples show that the approach used in this paper can produce a clear structural topology with a good actuator placement. Besides, the optimal topologies can improve the active damping.

O estudo das vibrações é importante para prevenir danos em equipamentos ou mesmo evitar catástrofes de grande natureza. Nesse sentido, aproveitar a energia que seria dissipada na vibração e contribuir no controle do sistema representa um grande avanço tecnológico. O termo Energy Harvesting (Colheita de Energia) está relacionado ao contexto do aproveitamento energético, utilizando sistema de conversão para transformação da energia em eletricidade. Através de um dispositivo com viga engastada e massa inercial na extremidade, é possível realizar o estudo de vibração e coleta de energia, ao se considerar uma estrutura piezelétrica acoplada na viga e conectada a um circuito elétrico com resistor. Estruturas inteligentes que atuam na conversão de energia mecânica em elétrica, ou vice-versa, são fundamentais para esse estudo, o que motiva a inclusão dos sensores piezelétricos no projeto de dispositivos estudados e sujeitos a vibrações. Por outro lado, otimizar parâmetros de projeto é fundamental para aumentar a amplitude de vibração e tornar o processo com maior desempenho, tendo em vista maior captação de energia. Ainda, parâmetros otimizados podem estar sujeitos a incertezas do projeto e variações, devido a flutuações ambientais, como temperatura, pressão, propriedades dos materiais, geometria, etc. Por isso, técnicas robustas que tornem os projetos menos sensíveis a variações são interessantes para serem abordadas. Embora métodos de projetos robustos sejam eficientes, poucas pesquisas têm sido feitas na área da dinâmica de vibrações e alguns processos podem demandar tempo computacional dependendo do estudo ou projeto. Este trabalho tem como propósito abordar um método específico de projeto robusto focado em uma metodologia com matrizes chamadas ortogonais. Além disso, o método determinístico via algoritmo de Programação Sequencial Quadrático (SQP) é utilizado. O trabalho consiste numa abordagem para coleta de energia em um modelo de viga engastada, otimizando parâmetros e inserindo incertezas no sistema para análise de robustez e verificação de comprimentos adequados de vigas para os dispositivos. Os resultados mostram um aumento da energia coletada, analisando funções de resposta em frequências para saída de potência, diante de uma entrada de deslocamento no engaste do dispositivo, projetado via otimização determinística, além de aumento de robustez de acordo com certos critérios considerando circuito elétrico com resistência corretamente selecionada. / The study of vibrations is important to prevent damage to equipment or even prevent major catastrophes. In this sense harvesting the energy that would otherwise be dissipated in vibration and contributing to the control of the system represents a great technological advance. The term Energy Harvesting is related to the context of energy use, using a conversion system to transform energy into electricity. Through a device with clamped beam and inertial mass at the end, it is possible to study the vibration and energy harvesting, considering a piezoelectric structure coupled to the beam and connected to a resistance electric circuit. Smart structures that act in the conversion of mechanical energy to electrical energy, or vice versa, are fundamental for this study, which motivates the inclusion of piezoelectric sensors in the design of studied devices and subject to vibrations. On the other hand, optimizing design parameters is fundamental to increase the amplitude of vibration and increase process performance, in view of greater power uptake. Furthermore, optimized parameters may be subject to design uncertainties and variations due to environmental fluctuations such as temperature, pressure, material properties, geometry, etc. Therefore, robust techniques that make designs less sensitive to variations are interesting to be addressed. Although robust design methods are efficient, few researches have been done in the area of vibration dynamics and some processes may require computational time depending on the study or project. This work aims to address a specific method of robust design focused on a methodology with matrices called orthogonal. In addition, the deterministic method using Sequential Quadratic Programming (SQP) algorithm is used. The work consists of an approach to harvest energy in a clamped beam model, optimizing parameters and inserting uncertainties in the system for robustness analysis and verification of adequate beam lengths for the devices. The results show an increase in the harvested energy, analyzing frequency response functions for power output, in the face of a displacement input in the device clamp, designed through deterministic optimization,besides increasing robustness according to certain criteria considering electric circuit with correctly selected resistance.

Filmes amorfos que não apresentam piezoeletricidade intrínseca, podem ser induzidos a mostrar um efeito piezoelétrico linear quando um fluxo de íons é estabelecido através dele. O efeito está relacionado ao efeito piezoelétrico induzido pela corrente elétrica, exceto que ele está presente ainda que o fluxo de íons positivo a negativo sejam iguais (corrente zero). Um filme circular de celofane é colocada entre duas células de vidro, tal que ela separa água pura de uma solução de cloreto de sódio (NaCl). A diferença de nível dos líquidos fornece uma pressão estática que mantém uma curvatura na membrana, ou no sentido da água ou no sentido da solução. Um transdutor eletromagnético acoplado a água e dirigido senoidalmente por um oscilado, deforma o filme ciclicamente, e eletrodos de platinam um de cada lado do filme, levam os sinais elétricos a um detector síncromo com a deformação aplicada. Enquanto o sinal elétrico observado poderia ser devido a efeitos espúrios dos eletrodos, a inversão observada na fase deste sinal com a mudança da curvatura indica que ele é dependente da deformação de um filme separando dois eletrólitos é devido `a modulação da mobilidade iônica pela deformação aplicada / Amorphous films which can have intrinsic piezoelectricity, can be induced to show a linear piezoelectric effect when a flux of ions is established across them. The effect is related to the electric current induced piezoelectric effect, except that is present even though positive and negative ion fluxes are equal (zero-current). A circular cellophane film is put between two glass cell, so that it separates pure water from a NaCl solution. A level difference of liquids provides a static pressure supports a membrane curvature, either towards or away from the water. An electromagnetic transducer, coupled to the water and driven sinusoidally by a oscillator deforms the film cyclically and platinum electrodes on either side of the film lead the electric signals to a detector synchronized with the applied deformation. While the electric signal observed might be due spurious effects from the electrodes, the observed might be due to spurious effects from the electrodes, the observed reversal in phase of the signal with the change of curvature of the film signifies that it is deformation-dependent. The deformation-dependent electricity in a film separating two electrolytes is owing to the modulation of the mobility of the ions by the applied deformation

En mécanique des matériaux et des structures, l’interface entre deux composants matériels ou deux éléments structuraux est traditionnellement et le plus souvent supposé parfaite. Au sens mécanique, une interface parfaite est une surface à travers laquelle le vecteur de déplacement et le vecteur de contrainte sont tous les deux continus. L’hypothèse des interfaces parfaites est inappropriée dans de nombreuses situations en mécanique. En effet, l’interface entre deux corps ou deux parties d’un corps est un endroit propice aux réactions physico-chimiques complexes et favorable à l’endommagement mécanique. L’intérêt pour les interfaces imparfaites devient depuis quelques années grandissant avec le développement des matériaux et structures nanométriques dans lesquels les interfaces et surfaces jouent un rôle prépondérant. A partir de la configuration de base où une interphase de faible épaisseur sépare deux phases, ce travail établit trois modèles d’interface imparfaite généraux qui permettent de remplacer l’interphase par une interface imparfaite dans les cas de la conduction thermique, de l’élasticité linéaire et de la piézoélectricité sans perturber les champs en questions à une erreur fixée près. La dérivation de ces modèles est basée sur le développement de Taylor et sur une approche originale de géométrie différentielle indépendante de tout système de coordonnées. Les trois modèles généraux permettent non seulement de mieux appréhender certains modèles phénoménologiques d’interface imparfaite mais aussi de décrire les effets d’interface que les modèles existants ne sont pas en mesure de prendre en compte. Les modèles d’interface imparfaite établis sont appliqués dans la détermination des propriétés effectives thermiques, élastiques et piézoélectriques d’un matériau composite constitué d’une matrice renforcée par des particules ou fibres enrobées d’une interphase. La méthode utilisée pour rendre compte des effets des interfaces imparfaites sur les propriétés effectives repose sur une condition d’équivalence énergétique qui ramène un matériau hétérogène avec interfaces imparfaites à un matériau hétérogène avec interfaces parfaites / In mechanics of materials and structures, the interface between two material components or two structural elements is traditionally and the most often assumed to be perfect. In mechanics, a perfect interface is a surface through which the displacement and stress vectors are continuous. The assumption of the perfect interfaces is inappropriate in many situations in mechanics. Indeed, the interface between two bodies or two parts of a body is a place propitious to complex physicochemical reactions and vulnerable to mechanical damage. The interest in imperfect interfaces has become for a few years growing with the development of nanometric materials and structures in which the interfaces and surfaces play a preponderant role. Starting from the basic configuration where an interphase of thin thickness separates two phases, this work establishes three general models of imperfect interface which make it possible to replace the interphase by an imperfect interface in the cases of thermal conduction, linear elasticity and piezoelectricity without disturbing the fields in questions to within a fixed error. The derivation of these models is based on the development of Taylor and an original coordinate-free approach of differential geometry. The three general models make it possible not only to get a better understanding of certain phenomenological models of imperfect interface but also to describe the effects of interface which the existing models are not able to take into account. The established models of imperfect interface are applied to determining the thermal, elastic and piezoelectric effective properties of composite materials consisting of a matrix reinforced by particles or fibers coated with an interphase. The method used to account for the effects of imperfect interfaces on the effective properties rests on an energy equivalency which brings back a heterogeneous material with imperfect interfaces to a heterogeneous material with perfect interfaces

Dans cette étude, nous avons déterminé les propriétés électroniques de plusieurs types de composés moléculaires possédant un élément métallique. Notre motivation pour l'étude de tels systèmes était de montrer qu'il était possible d'obtenir une description précise d'états électroniques très proches en énergie, pour lesquels il est connu que les effets relativistes jouent un rôle important. Pour traiter ces effets nous avons mis en oeuvre différentes approches et méthodes, en particulier des méthodes multiconfigurationnelles, des pseudopotentiels atomiques et de grandes bases de fonctions. Dans une première étude nous avons déterminé les propriétés des états électroniques de plus basse énergie de composés diatomiques MX dont l'association en phase solide conduit à des composés semi-conducteurs présentant des propriétés piézoélectrique importantes. A l'aide de calculs électroniques incluant une large part de la corrélation électronique nous avons mis en évidence les propriétés communes à une famille de composés diatomiques possédant huit électrons de valence et qui peuvent être considérés comme précurseurs des solides piézoélectriques. Il a ainsi été possible d'identifier les couples diatomiques qui constituaient les meilleurs candidats pour une production d'effet piézoélectrique en phase solide. Dans la deuxième application, nous avons calculé la structure électronique et les constantes spectroscopiques de l'état fondamental de la molécule HZnF ainsi que les états de plus basse énergie des fragments diatomiques associés. Cette étude était motivée par une analogie avec un système voisin HZnCl dont les premiers états électroniques présentent des caractéristiques non complètement résolues. Après avoir validé notre approche sur l'étude de ZnH et comparé nos résultats à ceux d'études antérieures, nous avons entrepris la détermination de la structure électronique des molécules ZnF et ZnCl pour lesquelles nous avons pu identifier des états électroniques encore mal connus. Utilisant les résultats obtenus sur ZnH et ZnF, nous avons déterminé la surface d'énergie potentielle de l'état fondamental de HZnF et nous en avons déduit plusieurs grandeurs spectroscopiques caractérisant cet état / In this work we have investigated the electronic properties of several types of molecular systems involving a metallic element. Our motivation for such applications on metallic compounds was to obtain an accurate description of close lying electronic states, in which the relativistic effects of heavy atoms are known to be important. Thus various approaches and methods have been employed to treat these effects, including the multi-configurational method, with atomic pseudopotentials and large basis sets. In the first study, we have determined the properties of the low lying electronic states of the diatomic compounds MX, whose combinations in the solid phase produce ionic semi-conductor materials with piezoelectric properties. Based on highly correlated ab initio calculations, we have elucidated the common properties of the low lying electronic states of these diatomic compounds with eight valence electrons, which can be considered as precursors for piezoelectric effects in their solid phase. Based on our electronic structure calculations, we could identify among these diatomic compounds those who could lead to good candidates for piezoelectric effects. As the second application, we have determined the electronic structure and the spectroscopic constants for the ground state of the HZnF molecule and for the low lying electronic states of its diatomic fragments. This application was initiated and motivated by interesting and puzzling results on the close system HZnCl. Comforted by our experience with the previous studies, we used the pseudopotentials approach to obtain an accurate description of the low lying states of ZnH which could be satisfactorily compared with existing data. Next, the ZnF and ZnCl diatomic molecules have been studied with the same ansatz to reveal the properties of so far unknown electronic states. Finally, the potential energy surface of the ground state of HZnF has been determined, and several spectroscopic properties have been deduced

L'allègement des structures est un enjeu économique important dans les domaines d'activités industrielles telles que l'automobile, l'aéronautique ou le naval, qui intègrent peu à peu les matériaux composites dans la fabrication des structures. Cet allègement s'accompagne d'un raidissement de la matière qui implique des problèmes de vibrations et d'isolation acoustique. Plusieurs méthodes de traitement existent pour diminuer les vibrations ou le bruit rayonné d'une paroi, mais ces méthodes ont l'inconvénient d'augmenter significativement la masse de la paroi. Afin de répondre à cette problématique, il est proposé dans cette thèse de modifier le comportement dynamique des structures à partir d'un réseau périodique de patchs piézoélectriques shuntés avec un circuit électrique dont il est possible de modifier l'impédance. En contrôlant ainsi le comportement dynamique des patchs piézoélectriques, il est possible de contrôler le comportement vibratoire de la structure et donc de traiter les problèmes de transmissions solidiennes ou de transmissions aériennes.La méthode de shunt choisie est la méthode dite de shunt à capacité négative qui permet de modifier la rigidité d'une structure. Cette méthode dite semi-passive présente plusieurs avantages : la mise en œuvre est simple, il est possible d'intégrer les patchs directement à l'intérieur de la paroi, elle consomme une faible quantité d'énergie électrique et sa mise en application est peu onéreuse. / Making the structure lighter is an important economic stake in the field of industrial activities such as automotive, aeronautic or naval, which gradually integrate composite materials in the manufacturing of structures. This reduction of the mass goes along with a stiffening of the matter implying acoustics and vibrations issues. Several methods exist to reduce vibrations or acoustic radiations of structures, but these methods increase the mass. In order to answer the problematic, we propose to change the dynamic behavior of structures with a periodic lattice of piezoelectric patches shunted with an electrical circuit whose the impedance can be controlled. Therefore, the control of the coupled behavior of the piezoelectric patches allows the control of vibrational wave's diffusion inside the structure and so to treat the structure-borne vibrations and airborne acoustics emission. The shunt method chosen is negative capacitance shunt which allows to modify the rigidity of a structure. This semi-passive method has several advantages: the implementation is simple, it is possible to integrate the patches directly inside the wall, it consumes a low amonte of electrical energy and its implementation is inexpensive.

Les céramiques piézoélectriques, comme le Titatano-Zirconate de Plomb (PZT), peuvent produire une tension électrique quand elles sont soumises à une contrainte mécanique et, inversement, se déforment sous l'effet d'un champ électrique. Ce couplage électromécanique peut être décrit par des équations de comportement linéaires pour des chargements modérés. Cependant, au-delà de certaines valeurs de champ électrique ou de contrainte mécanique, ce couplage devient fortement non linéaire à cause des phénomènes de réorientation de la polarisation électrique. Dans ce travail de thèse, un modèle phénoménologique, qui tient compte des réorientations ferroélectrique (par un champ électrique) et ferroélastique (par une contrainte mécanique) de la polarisation électrique, est proposé. Deux variables internes sont considérées pour décrire l'histoire du chargement et deux surfaces de charges électrique et mécanique sont définies pour déterminer les débuts des écoulements ferroélectrique et ferroélastique. Une version bi-dimensionnelle de ce modèle est développée également pour faire l'étude des structures piézoélectriques minces. Les deux versions 2D et 3D du modèle phénoménologique sont intégrées implicitement en adoptant la méthode de retour radial (prédiction/correction). Deux éléments finis coque et hexaédrique de premier ordre, qui intègrent ce modèle phénoménologique non linéaire, sont ensuite développés et implémentés dans le code de calcul par éléments finis Abaqus via la routine utilisateur UEL (User ELement) / Piezoceramics like lead zirconate titanate or PZT can produce an electric potential when they are subjected to a mechanical stress and deform in the presence of an electric field. This electromechanical coupling can be described by linear constitutive equations for moderate loadings. Nevertheless, this coupling becomes highly non linear when piezoceramics are subjected to high electromechanical loadings due to the electric polarization switching. In this thesis work, a phenomenological material constitutive model that describe the electric polarization ferroelectric switching (by an electric field) and ferroelastic switching (by a mechanical stress) is proposed. To describe the loading history, two internal variables are considered and two electric and mechanical loading surfaces are defined to indicate the onset of domain switchings. A bi-dimensional version of this model is developed to study thin piezoelectric structures. The phenomenological model 2D and 3D versions are implicitly integrated by adopting the return-mapping algorithm. Two shell and hexahedral first-order finite elements are then formulated and implemented into the commercial finite element code Abaqus via the user subroutine UEL (User ELement)

Piezoelektriska material används flitigt i olika sensorer då de kan generera en mätbar elektrisk signal vid tryck eller töjning. Arbetet utreder hur ett piezoelektriskt garn innehållandes Polyvinyldiflourid (PVDF) påverkas av faktorer som långvarig mekanisk deformation, fukt och värme. Fokus har legat på det piezoelektriska garnets egenskaper men projektet undersöker också hur integrering i tyg samt applicering i en textil produkt fungerar. Det piezoelektriska garnet har utsatts för ett stort antal tester. I de flesta tester har proverna utvärderats genom cyklisk deformation i en extensometer. Det piezoelektriska garnet har undersökts genom experiment i laboratoriemiljö, praktiska tester i textila applikationer samt vid statistisk analys. Det kan konstateras att yttre faktorer så som fukt och temperatur har inverkan på garnets piezoelektriska effekt. Långvariga tester avslöjar hur garnet uppvisar en längdförändring vid deformation som bidrar till garnets minskade signalstyrka. Garnet kan framgångsrikt integreras i tyg genom sömnad vid rätt inställning för stygnlängd, där högre stygnlängd ger bättre resultat. Samma metod kan användas för att konstruera en piezoelektrisk sensor som appliceras i en träningsstrumpa. Slutsatsen av detta arbete är att parametrar som fukt, krypningsbeteende samt strukturell variation i de individuella PVDF-filamenten har en betydande effekt på det piezoelektriska garnets elektriska signal. Potential i garnets förmåga att fungera som sensor kan ses genom att garnet integrerats med tyg på ett framgångsrikt sätt i en träningsstrumpa för mätning av fotnedsättning. Det kvarstår mycket gällande forskning kring piezoelektriska filament och garn. Vidare forskning i ämnet kommer kunna leda till nya innovativa applikationsmöjligheter som kan komma till nytta inom olika delar av samhället, inte minst inom medicinska användningsområden. / Piezoelectric materials are frequently used in different sensors as they can generate a measurable electrical signal during applied pressure or when subjected to extension. This project examines how a piezoelectric yarn containing Polyvinylidene fluoride (PVDF) is affected when exposed to moisture, heat and long-term mechanical deformation. Focus has been directed towards investigating the properties of the piezoelectric yarn as well as how it can be applied in textile fabrics and textile applications. The piezoelectric yarn has been subjected to a series of tests. Most of the samples have undergone cyclic deformation in an extensometer during tests. The piezoelectric yarn has been examined by experiments in laboratory environment, practical tests in textile applications as well as by statistical analysis. It can be stated that factors such as moisture and temperature have influence on the piezoelectric effect of the yarn. Long-term tests reveal how the yarn displays a change in length while undergoing deformation, which contributes to the diminished signal strength of the yarn. The piezoelectric yarn can successfully be integrated in a piece of fabric by the means of sewing when using correct stitch- length, where higher stitch-length gives a higher signal output. The same method can be applied to construct a piezoelectric sensor used in a training sock. This project can conclude that parameters such as moisture, creep-behaviour and structural variation within the PVDF-filaments have a significant effect on the signal created by the piezoelectric yarn. The potential of the yarn as a sensor can be seen by successfully applying it to a textile structure as well as in a training sock that can monitor the fore and rear foot while running. It can be stated that much remains to be studied in this particular research area regarding piezoelectric filaments and yarns. Further research in the subject will lead to new innovative applications that can be of use in different parts of society, not to say the least in the area of medicine.

Energy harvesting using piezoelectric nanomaterials provides an opportunity for advancement towards self-powered systems. Self-powered systems are a new emerging technology, which allows the use of a system or a device that perform a function without the need for external power source like for example, a battery or any other type of source. This technology can for example use harvested energy from sources around us such as ambient mechanical vibrations, noise, and human movement, etc. and convert it to electric energy using the piezoelectric effect. For nanoscale devices, the size of traditional batteries is not suitable and will lead to loss of the concept of “nano”. This is due to the large size and the relatively large magnitude of the delivered power from traditional sources. The development of a nanogenerator (NG) to convert energy from the environment into electric energy would facilitate the development of some self-powered systems relying on nano- devices. The main objective of this thesis is to fabricate a piezoelectric Zinc Oxide (ZnO) NGs for low frequency (˂ 100 Hz) energy harvesting applications. For that, different types of NGs based on ZnO nanostructures have been carefully developed, and studied for testing under different kinds of low frequency mechanical deformations. Well aligned ZnO nanowires (NWs) possessing high piezoelectric coefficient were synthesized on flexible substrates using the low temperature hydrothermal route. These ZnO NWs were then used in different configurations to demonstrate different low frequency energy harvesting devices. Using piezoelectric ZnO NWs, we started with the fabrication of sandwiched NG for hand writing enabled energy harvesting device based on a thin silver layer coated paper substrate. Such device configurations can be used for the development of electronic programmable smart paper. Further, we developed this NG to work as a triggered sensor for wireless system using foot-step pressure. These studies demonstrate the feasibility of using ZnO NWs piezoelectric NG as a low-frequency self-powered sensor, with potential applications in wireless sensor networks. After that, we investigated and fabricated a sensor on PEDOT: PSS plastic substrate either by one side growth technique or by using double sided growth. For the first growth technique, the fabricated NG has been used as a sensor for acceleration system; while the fabricated NG by the second technique has worked as anisotropic directional sensor. This fabricated configurations showed stability for sensing and can be used in surveillance, security, and auto-mobil applications. In addition to that, we investigated the fabrication of a sandwiched NG on plastic substrates. Finally, we demonstrated that doping ZnO NWs with extrinsic element (such as Ag) will lead to the reduction of the piezoelectric effect due to the loss of crystal symmetry. A brief summary into future opportunities and challenges are also presented in the last chapter of this thesis.

A redução do consumo de energia dos sistemas eletrônicos, fez com que a pesquisa de novas fontes de energia para alimentar estes dispositivos tivesse enorme importância na última década. Algumas destas fontes são provenientes da conversão de energia de vibrações mecânicas em energia elétrica. Veículos aéreos não tripulados (UAVs) e micro veículos aéreos (MAVs) constituem uma aplicação importante para utilização de geradores de energia baseados em vibrações. Este trabalho tem seu foco na conversão de oscilações aeroelásticas em eletricidade utilizando o efeito piezelétrico direto. Um modelo numérico piezoaeroelasticamente acoplado, proveniente da associação de um modelo por elementos finitos eletromecânico e um modelo aerodinâmico não estacionário é apresentado. Uma asa geradora de energia composta por uma subestrutura metálica e piezocerâmicas embutidas é modelada. Apresentam-se como resultados, saídas elétricas (tensão, corrente e potência elétrica) e mecânicas no domínio do tempo. Uma carga resistiva é assumida no domínio elétrico do problema. Uma rajada discreta do tipo \'1-cos\' é assumida para várias velocidades do escoamento e valores de resistências elétricas, utilizando eletrodos contínuos e segmentados. Aponta que os melhores resultados foram obtidos com a utilização de eletrodos segmentados e que em razão do melhor acoplamento eletromecânico, obtêm-se um maior efeito shunt damping, um aumento na velocidade de flutter (1 m/s neste trabalho) e uma maior geração de potência. / Reducing the power consumption of electronic systems, has led the research for new sources of energy to power these devices have great importance in the last decade. Some of these sources are from the conversion of energy from mechanical vibrations into electrical energy. Unmanned Aerial Vehicles (UAVs) and Micro Air Vehicles (MAVs) are an important application for use of vibration energy harvesting. This work focuses on conversion of aeroelastic oscillations into electricity using piezoelectric direct effect. A numerical model coupled piezoaeroelastically derived from the combination of an electro-mechanical finite element model and an unsteady aerodynamic model is presented. A power generator wing consists of a metal substructure and embedded piezoceramic is modeled. They appear as results, electrical outputs (voltage, current and electric power) and mechanical time domain. A resistive load is assumed in the electric domain of the problem. A discrete gust of shape \'1-cos\' is taken for various flow velocities and values of electrical resistances, using continuous and segmented electrodes. Indicates that the best results were obtained with the use of segmented electrodes and because of better electromechanical coupling, we obtain a higher shunt damping effect, an increase flutter speed (1 m/s in this work) and greater power generation.