Este trabalho tem como objetivo explorar a forma de planos de fachada vinculados à incidência solar, potencializando a aplicação de sistemas fotovoltaicos. A identificação e parametrização de formas segundo os princípios geométricos de captação fotovoltaica, sugerem a aplicação de uma metodologia de projeto para superfícies de fachadas fotovoltaicas, de modo a otimizar a incidência direta da radiação solar, incorporada a volumetria da edificação. O modelo de otimização de fachadas fotovoltaicas consiste em quatro etapas. Inicialmente define-se a tecnologia fotovoltaica e a localização geográfica (1). Posteriormente, é realizada a modelagem elementar tridimensional (2) através do editor de algoritmos gráficos Grasshopper – integrado à ferramenta de modelagem Rhinoceros3D – estabelecendo assim, as restrições e variáveis da forma. Na terceira etapa, correlacionamse transformações geométricas tridimensionais (twist, taper e shear) e incidência solar (3) por meio dos softwares Ecotect Analysis e Grasshopper. Com isso, os parâmetros dimensionais atribuídos às variáveis – transformações geométricas – são vinculados aos parâmetros de radiação solar, visando à geração de formas. Após a seleção das formas com maior potencial fotovoltaico, identificam-se as zonas com maior incidência de radiação solar e realiza-se a manipulação dos pontos de controle das superfícies NURBS (4). Através das transformações geométricas taper, shear e twist foi possível gerar um conjunto de soluções otimizadas, correlacionando dados energéticos e geométricos, integrando métodos de geração de formas e avaliação performática da radiação solar. O estudo identificou que as possibilidades de articulação entre os planos fotovoltaicos e a eficiência energética têm implicações positivas, correlacionando variabilidade formal e geração de energia elétrica. / This work aims explore the shape of façade planes linked to the solar incidence, in order to optimize the use of photovoltaic systems. The identification and parameterization of forms according to geometric principles of photovoltaic capture suggest the application of a design methodology for optimizing the photovoltaic surface façade in order to optimize direct solar radiation, incorporating the volume of the building. The optimization model of photovoltaic façade consists of four steps. Initially decide on the photovoltaic technology and geographic location (1). Subsequently, three-dimensional elementary modeling is performed (2) through the graphic-algorithm editor, Grasshopper, – integrated with the modeling tool, Rhinoceros 3D, – thus establishing, restrictions and variables in shape. In the third stage, threedimensional geometric transformations are correlated (twist, taper and shear) and solar incidence (3) through the computer interfaces of Ecotect Analysis and Grasshopper software. With this, the dimensional parameters assigned to the variables – geometric transformations – are linked to parameters of solar radiation, in order to generate shapes. After the selection of potential photovoltaic shapes, zones with the greatest incident solar radiation are identified and the control points of NURBS surface are manipulated (4). Using the geometric transformations taper, shear and twist, it was possible to generate a set of optimal solutions, correlating geometric and energetic data, integrating shape generating methods and performatic evaluation of solar exposure. The work identified that possibilities of articulation between photovoltaic planes and energetic efficiency have positive results, correlating shape variability and electricity generation.

Orientador: Marco Lucio Bittencourt / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-09T12:36:20Z (GMT). No. of bitstreams: 1 Martins_DanielLeonardo_M.pdf: 3435063 bytes, checksum: 5e1595f9983245a24712a596e4b1f0a1 (MD5) Previous issue date: 2007 / Resumo: Este trabalho apresenta uma metodologia de otimização de forma aplicada a estruturas submetidas a cargas de impacto, de modo a aumentar sua capacidade de absorção de energia de impacto. Para isso, é necessário conhecer as propriedades mecânicas dos materiais empregados em tais estruturas, as quais são obtidas através de uma metodologia de abordagem dupla experimental- otimização. São obtidos os parâmetros ótimos das leis constitutivas de Cowper-Symonds e Johnson-Cook para materiais sensíveis à taxa de deformação que melhor se ajustam aos respectivos dados experimentais. Finalmente, esses parâmetros são utilizados na análise de uma estrutura complexa, a qual tem sua capacidade de absorção de energia de impacto melhorada utilizando a Metodologia de Resposta da Superfície / Abstract: This work presents a shape optimization methodology applied to structures submitted to impact loads in order to improve their crashworthiness. To this end, it is necessary to know the structural material properties, which were obtained using a dual experimental-optimization methodology. Optimum parameters are obtained for the Cowper-Symonds and Johnson-Cook strain rate sensitive constitutive laws which best fit the material experimental data. These parameters were then used in the analysis of a complex structure, which is crashworthy optimized using a Response Surface Methodology / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Visando atender requisitos cada vez mais rigorosos de projeto e exigência dos consumidores, é necessário extrair o máximo desempenho de uma dada estrutura de produto, buscando sempre propriedades superiores as atuais. Para obter-se tais propriedades dinâmicas superiores (resistência, rigidez, peso) existem vários métodos de otimização estrutural, entre os quais a otimização de parâmetros, utilizada em ajustes finos de projeto; a otimização topológica, mais complexa e condicionada pelos processos de fabricação disponíveis e a otimização de forma utilizada em chapas estruturais. Dentre os métodos recentes de otimização de forma merece destaque o método de Padrões de Bossas por Formas Modais desenvolvido por Fredö e Hedlung (2004), que permite grandes ganhos de rigidez estrutural com pequenas deformações no formato das chapas. Entretanto, tal método tem sua aplicabilidade restrita, pois depende de fatores de ponderação cujo critério de escolha não foi explorado pelos autores. O presente trabalho analisa teoricamente o método desenvolvido por Fredö e Hedlung (2004), utilizando para tal uma chapa metálica em condições controladas para determinar um critério coerente de definição dos parâmetros de ponderação do método via otimização computacional suportado por uma análise modal via método dos elementos finitos. Com os resultados dessa análise pode-se criar um programa para implementação do método de Padrões de Bossas por Formas Modais em aplicações industriais, com ganhos significativos nas características estruturais de produtos sem impactos no custo final. / To meet increasingly higher design requirements and consumer demands for design, it is necessary to extract the maximum performance of a given product structure, always seeking superior properties versus current design. To obtain such superior dynamic properties (strength, stiffness, weight) there are several methods of structural optimization, including the parameters optimization used to fine-tune design; the topology optimization, more complex and conditioned by manufacturing processes and the shape optimization as used in structural plates. Among the newer methods for shape optimization, it is worth mentioning the Panel embossing pattern optimization method developed by Frëdo and Hedlung (2004), which allows large structural rigidity gains with small deformations in the plate shape. However, this method has a limited applicability because it depends on weighting factors whose selection criterion was unexplored by the authors. This work theoretically analyzes the method developed by Frëdo and Hedlung (2004), using for such a metal sheet under controlled conditions to determine a coherent criterion for the weighting parameters definition process using computational optimization supported by a modal analysis via finite element method. With the results of this analysis, it was possible to create a program to implement the method embossing pattern optimization method in industrial applications, with significant gains in structural characteristics of products without affecting the final cost.

Dans cette thèse nous développons une technique de déformation pour l'optimisation de formes. Les formes sont représentées par leur frontière, paramétrée par des courbes de Bézier par morceaux. En tant que courbes polynomiales, elles sont définies par leurs coefficients que l'on appelle plutôt points de contrôle. Bouger les points de contrôle revient à modifier la courbe et donc déplacer la frontière des formes. Dans un contexte d'optimisation de formes, ce sont alors les points de contrôle qui sont les variables du problème et l'on a transformé ce dernier en un problème d'optimisation paramétrique. Notre méthode de déformation consiste en un premier temps à paramétrer les frontières par des courbes de Bézier comme indiqué plus haut et dans un second temps à calculer une déformation des points de contrôle à partir d'une direction de descente de la fonction objectif. Notre méthode est de nature géométrique mais l'on propose un moyen de changer la topologie des formes en mesurant la distance entre les points de contrôle : on peut scinder une forme en deux ou inversement en réunir deux en une. Nous avons testé la méthode sur trois problèmes qui sont la conception d'un filtre micro-ondes, la détection d'inclusions et les trajectoires optimales. / We develop a deformation technique for shape optimization problems. The shapes are described only by their boundary, parameterized by piecewise Bézier curves. They are polynomial curves hence entirely defined by their coefficients which are called control points. By moving these control points the curves change and so is the boundary of the shape. Used in a shape optimization problem, the control points become the optimization variables meaning that the problem is a parametric optimization problem. Our method consists in first parameterizing the boundary of a shape by Bézier curves as stated above and then compute a deformation of the control points from a descent direction for the objective function. The method is almost purely geometric but we add a way to include topological changes by diving a shape into two or conversly merging two shapes into one. We tested our method on three particular shape optimization problems which are microwave filter design, inclusions detection and optimal trajectories.

In 21 century finned surfaces are used in almost all condensers to enhance their heat transfer capabilities. A lot of different models are presented in the literature: on horizontal and vertical finned tubes, inside finned tubes. The validation method of the theoretical models is based on comparison between measurement of average heat transfer coefficient and one calculated by the model. But in this case it is impossible to validate all approaches made in the theory.<p>\ / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

L'objectif de cette thèse est de trouver la forme optimale d'une antenne planaire ou d'un réseau d'antennes planaires à partir de contraintes imposées (diagramme de rayonnement, gain ou directivité) ou de reconstruire la forme à partir de mesures expérimentales. L'algorithme d'optimisation développé est basé sur une méthode de type gradient et la reconstruction des contours par une méthode d'ensembles de niveaux (Level Sets) ou "contours actifs". Le problème direct est résolu en utilisant une formulation intégrale du problème électromagnétique et une méthode d'éléments finis pour la discrétisation. Le gradient de forme est calculé en utilisant deux méthodes différentes. Tout d'abord, une méthode par différences finies basée sur la dérivée à un nœud du maillage, pour une modification infinitésimale des éléments triangulaires du contour, suivant la direction de la normale extérieure. La deuxième méthode est basée sur le gradient topologique pour le calcul de la déformation des contours. Une méthode d'ensembles de niveaux avec bande étroite a été développée pour faire évoluer le contour des antennes utilisant la vitesse de déformation calculée à partir du gradient de forme. Différentes configurations d'antennes et réseaux d'antennes planaires ont été utilisées pour étudier les performances de l'algorithme d'optimisation. Des techniques de type saut de fréquence et multifréquence ont été utilisées pour optimiser la forme dans une bande de fréquence. L'optimisation de forme pour la miniaturisation d'antennes planaires concerne de nombreuses applications, en particulier, pour les réseaux réflecteurs / The objective of this thesis work is to find the optimal shape of planar antenna elements and arrays from imposed constraints (e.g. desired or imposed radiation patterns, gain or directivity) or to reconstruct the shape from experimental measurements. The optimization algorithm is based on the gradient-type method and an active contour reconstruction by means of the Level Set method. The forward problem is solved using an integral formulation of the EM problem with finite element discretization. The shape gradient is computed using two different methods: one is finite differential method based on nodal point mesh derivation with an infinitesimal modification of the triangular elements on the contour along the outward normal direction, another the topological shape gradient, which is computed based on a topological deformation on a contour. A narrow band level set method has been developed to evolve the contour of antennas and arrays using the deformation velocity computed from the shape gradient. Different configurations of antennas and antenna arrays are studied for investigating the performance of the optimization algorithm. Frequency hopping and multi-frequency techniques have been used for optimizing the shape within a frequency band. Shape optimization for planar antenna miniaturization has a large number of applications, particularly, for reflectarrays

The Orbitrap is a mass analyzer that employs an electrostatic field to confine ions. The mass of an ion is determined from the frequency of its axial oscillations in the Orbitrap. The Orbitrap has high resolving power and accuracy. However, the electrodes of the Orbitrap have complicated curved shapes. As a consequence the Orbitrap is not easy to miniaturize. In this thesis we have proposed a class of easily machinable cylindrical-electrode structures to mimic the behavior of an Orbitrap. The proposed structure consists of a single cylinder and many coaxial equally spaced thick rings. A detailed numerical simulation of the cylindrical-electrode structure reveals that axial ion oscillations in it have many spurious frequency components in addition to the dominant frequency component. We have carried out a systematic shape optimization that adjusts the dimensions of the structure to minimize the amplitudes of the spurious frequency components of ion motion in the axial direction. The performance of the optimized structure was found to rival that of a practical Orbitrap.

[pt] Esse trabalho propõe uma implementação numérica para otimização de forma em problemas bi-dimensionais de elasticidade. O objetivo principal é propor uma metodologia eficiente e robusta para solução de problemas de otimização de forma considerando a minimização de concentração de tensões. Na implementação proposta, a análise estrutural é realizada pelo Método dos Elementos de Contorno Simétrico de Galerkin (MECSG), evitando-se assim a dispendiosa etapa de geração da malha. A avaliação das tensões no contorno é obtida por meio de um método preciso, ideal para problemas com concentrações de tensões. Outro aspecto relevante na implementação é a adequada partição das equações do MECSG de forma a reduzir, consideravelmente, o esforço computacional associado à etapa da análise estrutural. O problema de otimização é resolvido utilizando-se um método de otimização moderno, conhecido como Programação Cônica de Segunda Orderm (PCSO). Especificamente, busca-se a reposta do problema de otimização não linear por meio da solução de uma sequência de subproblemas de PCSO. / [en] In this work a numerical implementation of shape optimization in two-dimensional linear elasticity problems is proposed. The main goal is to propose a robust and efficient methodology for the solution of shape optimization problems regarding the minimization of stress concentration effects. In the proposed implementation, the structural analysis is performed by the Symmetric Galerkin Boundary Element Method (SGBEM), thus disposing of the mesh generation burden. The boundary stress evaluation is carried out by an accurate approach which is ideally suited for problems with stress concentrations. Another relevant feature of the proposed implementation is a suitable partition of the SGBEM equations which aims at reducing the computational effort associated with the structural analysis stage. The solution for the optimization problem is obtained by means of a modern numerical optimization method, the so-called Second Order Conic Programming (SOCP). Specifically, the solution for the non-linear optimization is sought by solving a sequence of SOCP subproblems.

O projeto de estruturas e máquinas deve considerar as restrições impostas pelas condições de contorno. Tais condições podem ser de natureza dinâmica, limitando assim as faixas de frequência às quais a estrutura ou máquina pode operar. Dentre as diferentes ferramentas disponíveis para trabalhar com restrições dinâmicas, a otimização de forma se mostra como uma interessante alternativa para afastar as frequências naturais das faixas problemáticas. Um modelo de elementos finitos de malha de 4x5 elementos é correlacionado com os resultados de uma análise modal experimental, e a otimização é realizada utilizando-se o software Nastran. Após usinar a placa com a espessura otimizada, boa concordância é atingida entre os resultados experimentais e os previstos numericamente. Apesar dos bons resultados, obter a placa com 4x5 elementos, cada qual com sua espessura, foi difícil por conta das dimensões envolvidas. É mais apropriado fabricar uma superfície contínua na placa com uma geometria conhecida. Para isso, modelos com malhas mais finas são necessários no procedimento de otimização, e tal quantidade de variáveis nem sempre converge a uma solução. De fato, um modelo com 48x60 elementos para a placa estudada não convergiu a uma solução para as mesmas frequências desejadas. A contribuição principal deste trabalho é mostrar que uma interpolação (linear ou cúbica) dos resultados de uma otimização de forma de malha grossa leva à solução do problema de otimização de uma malha mais refinada. Em outras palavras, é possível obter uma geometria de superfície contínua que otimiza frequências naturais em placas a partir de modelos de elementos finitos de malha mais grossa, sendo assim desnecessários modelos de malhas muito refinadas e altos custos computacionais. / The design of structures and machines must consider the restrictions imposed by the boundary conditions. Such conditions can be of dynamic nature, thus limiting the frequency ranges that the structure/machine can operate. Among the different design tools available for dealing with dynamics restrictions, shape optimization is an interesting way of deviating natural frequencies from problematic ranges. In this work, one presents the shape optimization of a cantilever plate aiming at desired natural frequencies. A 4x5 elements grid finite element model is correlated to results from experimental modal analysis, and the optimization is done with help of Nastran software. After machining the plate with optimized thickness, good agreement is achieved between experimental and numerically predicted results. Despite successful results, machining the plate in 4x5 discrete elements with individual (stepped) thickness showed to be cumbersome. It is more appropriated to machine a smooth surface on the plate with known geometry. For that, finer grid element models are necessary in the optimization procedure, and such amount of design variables not always converge to a solution. In fact, a model with 48x60 elements for the plate in study did not converge to a solution for the same target frequencies. The main contribution of this work is showing that an interpolation (linear or cubic) of the coarser grid shape optimization results leads to the solution of a finer grid optimization problem. In other words, it is possible to obtain the smooth surface geometry that optimizes natural frequencies in plates from coarser grid finite element models, thus not requiring fine grid models and high computational costs.

Cette thèse est consacrée à la conception, au développement et à l'analyse de méthodes de déformation de maillage pour la modélisation, le traitement et la comparaison de forme -telles que l'appariement et la reconstruction de surface- ainsi qu’à la conception d'une méthode numérique robuste pour la reconstruction faciale. La reconstruction faciale tridimensionnelle consiste à estimer un visage numérique à partir de la seule donnée de son crâne sec. Il s'agit d'un défi en médecine légale et en anthropologie. La contribution majeure de cette thèse est la conception d'une nouvelle méthode pour l'appariement de forme, en s'appuyant sur des techniques d'optimisation de forme. Sous la seule hypothèse que les deux formes ont la même topologie, la transformation cherchée s'obtient comme une suite de déplacements élastiques, solutions d'un problème de minimisation d’énergie basée sur une fonction distance signée.Nous proposons également une méthode de drapage permettant la génération d'un modèle de surface fermée à partir d'un maillage source. La méthode repose sur une technique d’évolution de maillage utilisant les équations de l'élasticité linéaire. Un maillage modèle est itérativement déformé pour générer une séquence de formes qui s’approche de plus en plus de la triangulation source. Dans la deuxième partie de ce manuscrit, nous nous intéressons au développement d’une méthode automatique de reconstruction faciale numérique. En s’appuyant sur des techniques de déformation continue telles que le ‘morphing' et le ’warping’, l'approche proposée est intégrée par des connaissances anthropologiques et mécaniques. / This thesis is devoted to the conception, the development and the analysis of mesh deformation strategies for shape modeling, processing and comparison -as shape matching and surface reconstruction- and, in a rather independent concern, for devising a robust computational method for facial reconstruction. Facial reconstruction is about the estimation of a facial shape from the sole datum of the underlying skull and is a challenging problem in anthropology and forensic science. The main contribution of the thesis is the design of a novel method for shape matching, borrowing techniques from the shape optimization context. Under the sole assumption that the two shapes share the same topology, the desired mapping is achieved as a sequence of elastic displacements by minimizing an energy functional based on a signed distance function. Several numerical examples are presented to show the efficiency of the method.Also, a novel method for generating a closed surface mesh model of an initially non-closed source mesh model is developed. The method relies on an original PDE-based mesh evolution technique. A template shape is iteratively deformed, producing a sequence of shapes that get 'closer and closer' to the source triangulation.The second part of the manuscript deals with the development of a landmark-free, fully automated method for digital facial reconstruction. Based on techniques of continuous deformation as 'morphing' and 'warping', the proposed approach is integrated with anthropological assumptions and mechanical models.