Orientador: Alberto Luiz Serpa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-22T23:18:09Z (GMT). No. of bitstreams: 1 Medeiros_MarianeMendes_M.pdf: 1617094 bytes, checksum: d2be1eafefa6985fbd91c7c052f71868 (MD5) Previous issue date: 2013 / Resumo: O presente trabalho propõe o estudo de estruturas flexíveis e controle de vibrações sob a ótica da otimização simultânea de ambos. Iniciando pela modelagem da estrutura, é apresentada a justificativa para o uso de Elementos Finitos e modelagem no Espaço de Estados, passando ainda pela realização balanceada e redução de ordem do sistema. Na sequência, é descrita a síntese do controlador ??, que parte do princípio da minimização da Norma ?? do sistema. A solução do problema é então apresentada sob a abordagem das Desigualdades Matriciais Lineares, enfoque mais atual devido às suas propriedades de linearidade e convexidade quando aplicada dentro da teoria de controle. Em se tratando do processo de otimização, é desenvolvido um estudo sobre o método simultâneo, onde parâmetros da estrutura são otimizados juntamente com os do controlador de maneira a diminuir os efeitos negativos entre as dinâmicas quando otimizadas separadamente. Ainda assim, são apresentadas duas outras abordagens como forma de comparação: a Ativa Serial e a Passiva Estrutural. Para todos os três casos, a técnica escolhida para a resolução do problema de otimização foi o Algoritmo Genético, cujas vantagens e desvantagens são mostradas junto com toda a descrição de conceitos envolvidos, considerando seus operadores, fluxo algorítmico e até mesmo critérios de parada. Por fim, serão apresentados os resultados analisados sobre um modelo de uma viga engastada, submetida à distúrbios externos, através de uma simulação em MATLAB que engloba todos os conceitos estudados / Abstract: The present work proposes the study of flexible structures and vibration control under the light of simultaneous optimization. Starting by structure modeling, it presents the reason for use Finite Element and State-Space modeling, passing also through the balanced realization and order reduction of the system. Sequentially, it describes the synthesis of ?? controller, which considers the minimization of ?? norm of the system. The solution of the problem is then presented under Linear Matrix Inequalities approach, the most up-to-date method due to linearity and convexity properties when applied to control theory. Regarding optimization process, it is developed a study of a simultaneous optimization method where structure parameters are optimized along with the controller ones, aiming to diminish negative influence between dynamics when separately optimized. Even tough, two other approaches are presented by means of comparison: Serial Active and Structural Passive. For all three cases, the chosen technique to solve the optimization problem was the Genetic Algorithm whose advantages and disadvantages are shown along with a description of all involved concepts, considering its operators, algorithmic flux and even stopping criteria. Last, the results analysed over a clamped beam model subjected to external disturbances are shown, through a MATLAB simulation that encloses all studied concepts / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Na presente tese é resolvida a equação de difusão de nêutrons estacionária, bem como problemas de cinética, em geometria unidimensional cartesiana multi-região considerando o modelo de multigrupos de energia. Um dos objetivos e inovação neste trabalho é a obtenção de uma solução aproximada com estimativa de erro, controle de precisão e na forma de uma expressão analítica. Com esse tipo de solução não há a necessidade de recorrer a esquemas de interpolação, geralmente necessários em caso de discretizações do domínio. O fluxo de nêutrons é expandido em uma série de Taylor cujos coeficientes são encontrados utilizando a equação diferencial e as condições de contorno e interface. O domínio é dividido em várias células, cujo tamanho e o grau do polinômio são ajustáveis de acordo com a precisão requerida. Para resolver o problema de autovalor é utilizado o método da potência. A metodologia é aplicada em um benchmark que consiste na solução da equação de difusão como condição inicial e na solução de problemas de cinética para diferentes transientes. Os resultados são comparados com sucesso com resultados da literatura. A convergência da série é garantida pela aplicação de um raciocínio baseado no critério de Lipschitz para funções contínuas. Cabe ressaltar que a solução obtida, em conjunto com a análise da convergência, mostra a solidez e a precisão dessa metodologia. / In the present dissertation the one-dimensional neutron diffusion equation for stationary and kinetic problems in a multi-layer slab has been solved considering the multi-group energy model. One of the objectives and innovation in this work is to obtain an approximate solution with error estimation, accuracy control and in the form of an analytical expression. With this solution there is no need for interpolation schemes, which are usually needed in case of discretization of the domain. The neutron flux is expanded in a Taylor series whose coefficients are found using the differential equation and the boundary and interface conditions. The domain is divided into several layers, whose size and the polynomial order can be adjusted according to the required accuracy. To solve the eigenvalue problem the conventional power method has been used. The methodology is applied in a benchmark problem consisting of the solution of the diffusion equation as an initial condition and solving kinetic problems for different transients. The results are compared successfully with the ones in the literature. The convergence of the series is guaranteed by applying a criterion based on the Lipschitz criterion for continuous functions. Note that the solution obtained, together with the convergence analysis, shows the robustness and accuracy of this methodology.

Orientador: Renato Pavanello / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-28T11:58:24Z (GMT). No. of bitstreams: 1 Calixto_TainanKhalilLeite_M.pdf: 15775150 bytes, checksum: e5e4d45becc32f922a1fd31b8f9bd3ab (MD5) Previous issue date: 2015 / Resumo: A utilização de materiais de alta performance se tornou uma realidade em diversos campos da engenharia, como na indústria automotiva e aeroespacial, devido aos avanços nas técnicas de manufatura aditiva. Por outro lado, sabe-se que a otimização topológica estrutural é uma ferramenta de desenvolvimento de estruturas com ampla aplicação industrial. Dentre os vários métodos de otimização topológica existentes, a otimização estrutural evolucionária tem se destacado pela sua versatilidade, podendo ser utilizada em diversos tipos de problemas de engenharia. Na tentativa de combinar esses campos, este trabalho consiste no estudo do método de otimização evolucionária BESO (Bi-directional Evolutionary Structural Optimization) aplicado a sistemas bidimensionais multiescala a fim de se projetar as topologias ótimas, em ambas as escalas, de uma estrutura. A análise do modelo multiescala é feita através do método da homogeneização, onde o padrão do material microestrutural é considerado periódico. O algoritmo implementado pode buscar dois objetivos distintos: a minimização da flexibilidade média, que resulta na maximização da rigidez global; ou a maximização da frequência fundamental. Resultados numéricos do algoritmo são apresentados para o projeto de materiais, onde apenas a microestrutura é otimizada, e de estruturas, na qual otimiza-se as topologias nas duas escalas. Para a análise do desempenho do método de otimização multiescala, são propostos um índice de eficiência estrutural e uma metodologia de fabricação de estruturas periódicas / Abstract: High-performance materials utilization became a reality in many fields of actual engineering, such as in automotive and aerospace industries, due to advances in additive manufacturing techniques. In the other hand, structural topology optimization is a powerful tool for the structure development with wide industrial application. Among the various optimization methods, evolutionary structural optimization stands out for its versatility and it can be used in many engineering problems. As an attempt to combine these fields, this work intends to study the Bi-directional evolutionary Structural Optimization method applied to two-dimensional multi-scale systems in order to design the optimal topologies of structures in both scales. The analysis of multi-scale model is made using the homogenization method, where the pattern of the micro-structural material is considered periodic. The implemented algorithm can use two different objective function: mean compliance minimization, which results in maximizing the global stiffness; or fundamental frequency maximization. Numerical results are presented for material design, where only the micro structure is optimized, and for structural design, in which the topologies in both scales are optimized. Deepening the study in multiscale optimization, it is proposed an index to analyse the structural efficiency and also a manufacturing methodology of periodic structures / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23153号 / 工博第4797号 / 新制||工||1750(附属図書館) / 京都大学大学院工学研究科建築学専攻 / (主査)教授 大崎 純, 教授 竹脇 出, 准教授 倉田 真宏 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Les travaux présentés dans ce mémoire proposent une nouvelle méthode d'optimisation globale dénommée MPSO-SA. Cette méthode hybride est le résultat d'un couplage d'une variante d'algorithme par Essaim de particules nommé MPSO (Particle Swarm Optimization) avec la méthode du recuit simulé nommé SA (Simulted Annealing). Les méthodes stochastiques ont connu une progression considérable pour la résolution de problèmes d'optimisation. Parmi ces méthodes, il y a la méthode Essaim de particules (PSO° qui est développée par [Eberhart et Kennedy (1995)]. Quant à la méthode recuit simulé (SA), elle provient du processus physique qui consiste à ordonner les atomes d'un cristal afin de former une structure cristalline parfaite. Pour illustrer les performances de la méthode MPSO-SA proposée, une comparaison avec MPSO et SA est effectuée sur des fonctions tests connues dans la littérature. La métode MPSO-SA est utilisée pour la résolution des problèmes réels interopérabilité des systèmes d'information, ainsi qu'aux problèmes d'optimisation et de fiabilité des structures mécaniques. / The work presented in this PhD thesis contibutes to a new method for a modified particle swarm optimization algorith (MPSO) combined with a simulating annealing algorithm (SA). MPSO is known as an efficient approach with a high performance of solving optimization problems in many research fields. It is a population intelligence algorithm [Eberhart et Kennedy (1995)] inspired by social behavior simulations of bird flocking. Considerable research work on classical method PSO (Particle Swarm Optimization) has been done to improve the performance of this method. Therefore, the propose hybrid optimization algorithms MPSOSA use the combination of MPSO and simulating annealing SA. This method has the avantage to provide best results comparing with all heuristics methods PSO and SA. In this matter, a benchmark of eighteen well-known functions is given. These functions present different situations of finding the global minimum with gradual difficulties. Numerical results presented, in this paper, show the robustness of the MPSOSA algorithm. Numerical comparisons with three algorithms namely, Simulating Annealing, Modified Particle swarm optimization and MPSO-SA show that hybrid algorithm offers better results. This method (MPSO-SA) treats a wide range of optimization problems, in information systems interoperability and in structural optimization field.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18585号 / 工博第3946号 / 新制||工||1606(附属図書館) / 31485 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 西脇 眞二, 教授 田畑 修, 教授 松原 厚 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The intention of this thesis is to develop, evaluate new concepts and look over the current design for a container sized barge module. By request of Group Ocean, a cost and weight reduction is the main improvement criteria along with keeping the strength of the module.Five concepts are developed, analyzed and discussed with the supervisor at Group Ocean, where three are decided to be presented here. The other two are left out, since they are considered way too expensive without giving a satisfying result. The three concepts that are developed throughout this thesis are; changing to high strength steel, changing to sandwich panels and increasing stiffeners with smaller dimensions.A structural optimization is made in the software MATLAB to find out the best dimension to use for the sandwich panels. To determine the local stresses, the finite element method is used in Inventor Professional. It is also where the design and CAD modules are built in, so for simplifications it is used for FEA (Finite Element Analysis) as well. To reduce the amount of elements and nodes, shell elements and other structural constraints are used in the FEA. All the concepts are modelled with the same structural constraints so a practical comparison study can be made.The final designs resulted in a total weight reduction up to 40% with a material cost reduction of 12%. Based on what type of material is chosen, the material cost reduction range is between 3-12% and the weight reduction range is between 13-40%.

Civil engineering projects involve great investments and great impacts. For that reason,engineers have a commitment with an efficient and optimal use of resources. Researchers inuniversities claim that a lot could be achieved by applying structural optimization into realprojects, even though this approach has not gained the same popularity in the industry over thelast decades.The purpose of the present thesis is to explore the possibilities offered by structural optimizationand to verify its applicability in realistic and complex structural engineering problems. Amongthe questions regarding design optimization, it was emphasized feasibility, efficiency and userfriendliness. The chosen structural system was a bridge cantilever deck. The analysis was limitedto the transversal design of the structure and the goal of the optimization was to reduce investmentcosts. In order to guarantee efficiency of the simulations, a "longitudinal length convergence"analysis was performed. It consisted of determining the minimum required longitudinal length(perpendicular to the cantilever length) that ensured reasonable accuracy. The purpose of thisanalysis was to reduce the computational time during the optimization process. In order toautomate the analysis, MATLAB was used in connection to Abaqus (to perform the FE Analysis).There were three different sets of results presented: the length convergence, application toreal projects and parametric study. In the first application, it was shown that the requiredlongitudinal length (lx) proportionally decreased as the cantilever length (lc) increased. It wasalso observed the presence of the edge beam implied in consistently larger longitudinal lengthsfor the same accuracy tolerance. With respect to the second application, two projects wereconsidered and the structural optimization presented alternatives with significant investment costreduction in a reasonable time. Furthermore, it was observed that a design solution without theedge beam reduced the costs even more. Finally, the parametric study confirmed that the costreduction obtained by eliminating the edge beam was not restricted to only certain cantileverlengths. Furthermore, it was possible to obtain the pattern of thickness variation as function ofthe cantilever length.The results of this research suggest that structural optimization could be an alternative totraditional design methods used today in consulting offices and its possibilities transcend puredesign achievements.

A procedure for generating a customized weight function for wing bending material weight of a High Speed Civil Transport (HSCT) is described. The weight function is based on HSCT configuration parameters. A response surface methodology is used to fit a quadratic polynomial to data gathered from a large number of structural optimizations. To reduce the time of performing a large number of structural optimizations, coarse-grained parallelization with a master-slave processor assignment on an Intel Paragon computer is used. The results of the structural optimization are noisy. Noise reduction in the structural optimization results is discussed. It is shown that the response surface filters out this noise. A statistical design of experiments technique is used to minimize the number of required structural optimizations and to maintain accuracy. Simple analysis techniques are used to find regions of the design space where reasonable HSCT designs could occur, thus customizing the weight function to the design requirements of the HSCT, while the response surface itself is created employing detailed analysis methods. Analysis of variance is used to reduce the number of polynomial terms in the response surface model function. Linear and constant corrections based on a small number of high fidelity results are employed to improve the accuracy of the response surface model. Configuration optimization of the HSCT employing a customized weight function is compared to the configuration optimization of the HSCT with a general weight function. / Ph. D.

[pt] A crescente demanda de óleo observada nas últimas décadas tem motivado as indústrias de petróleo a explorarem novas reservas em águas cada vez mais profundas, o que representa um maior desafio operacional, de segurança e econômico. Nesse novo cenário, as condições ambientais se tornam mais severas, conferindo às unidades flutuantes movimentos de amplitude cada vez maiores. Em consequência, os risers, que são os principais componentes responsáveis pelo transporte de óleo desde o reservatório até as unidades flutuantes, passam a ser solicitados de forma mais intensa. Um grande desafio tem sido colocado para as indústrias de petróleo no sentido de desenvolverem configurações para os risers capazes de reduzir os efeitos dinâmicos que lhes são impostos e, consequentemente, viabilizarem o seu uso em águas profundas e ultraprofundas. Configurações do tipo Lazy-S, Pliant-Wave, entre outras, têm sido propostas, porém, além de complexas, demandam muita logística e apresentam elevados custos para a sua implantação. Esta dissertação propõe uma solução alternativa que consiste no estudo de configurações ótimas de risers em catenária utilizando amortecedores hidrodinâmicos. As dimensões e o posicionamento desses amortecedores são obtidos por meio de técnicas de otimização multiobjetivo, buscando-se minimizar os efeitos provocados pelas ondas de compressão ao longo dos risers e os custos envolvidos na utilização desses amortecedores, respeitando-se algumas restrições geométricas. O processo de otimização é realizado por meio do algoritmo genético NSGA-II, disponível no programa modeFRONTIER. O equilíbrio dinâmico dos risers, verificado em cada passo da otimização, é obtido por meio do programa Anflex. Exemplos representativos são utilizados para demonstrar a eficiência e a viabilidade da utilização da metodologia proposta. / [en] The growing demand for oil, observed in recent decades has motivated the oil industry to exploit new oil reserves in ever-deeper waters, representing a greater operational challenge, security and economic. In this new scenario, the environmental conditions become more severe, causing the floating units movements with increasing amplitude. Consequently, the risers, which are the main components responsible for the transport of oil from the reservoir to the floating units, shall be requested more intensely. The oil industry confronts a major challenge in order to develop riser configurations that can reduce the dynamic effects that are imposed on it and hence to enable its use in deep and ultra-deep waters. Lazy-S, Pliant-Wave, among others riser configurations, have been proposed, however, besides complex, require a lot of logistics and have high costs for their deployment. This thesis proposes an alternative solution that consists of the study of optimum catenary risers configurations using hydrodynamic dampers. The dimensions and placement of these dampers are obtained by means of multi-objective optimization techniques seeking to minimize the effects caused by compression waves over the risers and the costs involved in using these dampers, fullfilling certain geometric constraints. The optimization process is performed by the genetic algorithm NSGA-II, available at modeFRONTIER program. The dynamic equilibrium of risers, evaluated at each step of the optimization is obtained through Anflex program. Representative examples are used to demonstrate the efficiency and feasibility of using the proposed methodology.