Dissertations / Theses: 'Topological optimization'

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Hassani, B. "Homogenization and topological structural optimization." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493797.

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Da, Daicong. "Topological optimization of complex heterogeneous materials." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1102/document.

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Les propriétés effectives mécaniques et physiques des matériaux hétérogènes dépendent d'une part de leurs constituants, mais peuvent également être fortement modifiées par leur répartition géométrique à l'échelle de la microstructure. L'optimisation topologique a pour but de définir la répartition optimale de matière dans une structure en vue de maximiser un ou plusieurs objectifs tels que les propriétés mécaniques sous des contraintes telles que la masse de matière. Récemment, les développements rapides de l'impression 3D ou d'autres techniques de fabrication additive ont rendu possible la fabrication de matériaux avec des microstructures "à la demande", ouvrant de nouvelles perspectives inédites pour la conception de matériaux. Dans ce contexte, les objectifs de cette thèse sont de développer des outils de modélisation et de simulation numériques pour concevoir des matériaux et des structures hétérogènes ayant des propriétés optimisées basés sur l'optimisation topologique. Plus précisément, nous nous intéressons aux points suivants. Premièrement, nous proposons des contributions à l'optimisation topologique à une seule échelle. Nous présentons tout d'abord une nouvelle méthode d'optimisation topologique avec évolution pour la conception de structures continues par description lisse de bords. Nous introduisons également deux techniques d'homogénéisation topologique pour la conception de microstructures possédant des propriétés effectives extrêmes et des « méta propriétés » (coefficient de Poisson négatif).Dans une seconde partie, des techniques multi échelle basées sur l'optimisation topologique sont développées. Nous proposons d'une part une approche concourante de structures hétérogènes dont les microstructures peuvent posséder plus de deux matériaux. Nous développons ensuite une approche d'optimisation topologique dans un cadre d'homogénéisation pour des échelles faiblement séparées, induisant des effets de gradient. Enfin dans une troisième partie, nous développons l'optimisation topologique pour maximiser la résistance à la fracture de structures ou de matériaux hétérogènes. La méthode de champs de phase pour la fracture est combinée à la méthode BESO pour concevoir des microstructures permettant d'augmenter fortement la résistance à la rupture. La technique prend en compte l'initiation, la propagation et la rupture complète de la structure Mechanical and physical properties of complex heterogeneous materials are determined on one hand by the composition of their constituents, but can on the other hand be drastically modified by their microstructural geometrical shape. Topology optimization aims at defining the optimal structural or material geometry with regards to specific objectives under mechanical constraints like equilibrium and boundary conditions. Recently, the development of 3D printing techniques and other additive manufacturing processes have made possible to manufacture directly the designed materials from a numerical file, opening routes for totally new designs. The main objectives of this thesis are to develop modeling and numerical tools to design new materials using topology optimization. More specifically, the following aspects are investigated. First, topology optimization in mono-scale structures is developed. We primarily present a new evolutionary topology optimization method for design of continuum structures with smoothed boundary representation and high robustness. In addition, we propose two topology optimization frameworks in design of material microstructures for extreme effective elastic modulus or negative Poisson's ratio. Next, multiscale topology optimization of heterogeneous materials is investigated. We firstly present a concurrent topological design framework of 2D and 3D macroscopic structures and the underlying three or more phases material microstructures. Then, multiscale topology optimization procedures are conducted not only for heterogeneous materials but also for mesoscopic structures in the context of non-separated scales. A filter-based nonlocal homogenization framework is adopted to take into account strain gradient. Finally, we investigate the use of topology optimization in the context of fracture resistance of heterogeneous structures and materials. We propose a first attempt for the extension of the phase field method to viscoelastic materials. In addition, Phase field methods for fracture able to take into account initiation, propagation and interactions of complex both matrix and interfacial micro cracks networks are adopted to optimally design the microstructures to improve the fracture resistance

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Shikhman, Vladimir [Verfasser]. "Topological aspects of nonsmooth optimization / Vladimir Shikhman." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1018219897/34.

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Kaveh, Mohammad. "Topological optimization of rigidly jointed space frames." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238227.

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OLIVEIRA, ANDRE PIMENTEL DE. "APPLICATION OF TOPOLOGICAL DERIVATIVE IN STRUCTURAL OPTIMIZATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36089@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR PROGRAMA DE EXCELENCIA ACADEMICA A otimização topológica tem por objetivo buscar uma distribuição ótima de uma quantidade limitada de material em um dado domínio, de tal maneira a minimizar uma medida de desempenho, como, por exemplo, a flexibilidade da estrutura. Tradicionalmente, são utilizados algoritmos clássicos, baseados em gradiente, para se encontrar a solução deste problema de otimização. Este trabalho propõe a aplicação de uma técnica alternativa, baseada no conceito de derivada topológica, para a solução do problema de otimização topológica em domínios bidimensionais arbitrários, utilizando malhas de elementos finitos poligonais. Inicialmente, são apresentados os conceitos básicos da expansão assintótica topológica na solução de problemas de elasticidade linear em um domínio com pequenas perturbações. Usamos esse conceito para definir a derivada topológica a partir da solução desse problema e de um equivalente em um domínio sem perturbações. Em seguida, discutimos a obtenção da derivada topológica em problemas unidimensionais simples para depois estender este conceito para problemas de elasticidade linear bidimensional. Apresentamos uma implementação computacional da derivada topológica, em MATLAB, e aplicamos o código desenvolvido na solução de problemas de otimização topológica, conhecidos na literatura. Finalmente, apresentamos as conclusões sobre a qualidade dos resultados obtidos e a eficiência computacional da implementação proposta e sugerimos alguns tópicos para futuros desenvolvimentos. The purpose of topology optimization is to find the optimum material distribution of a limited amount of material in a given domain, in such a way that it minimizes a performance measure, such as the structure s compliance. Traditionally, classical algorithms based on gradients are used to obtain the solution of optimization problems. This work proposes the application of an alternative technique, based on the topological derivative concept, for the solution of topology optimization problems in arbitrary two-dimensional domains, using polygonal finite element meshes. Initially, the basic concepts of topological asymptotic expansion of linear elasticity problems in a domain with small perturbations are presented. We use this concept to define the topological derivative from the solution of this problem and an equivalent one on a domain without perturbations. Then, we discuss how to calculate the topological derivative for one-dimensional problems before extending this concept to two-dimensional linear stability problems. We present a computational implementation of the topological derivative in MATLAB, and apply the developed code to solve topology optimization problems known in the literature. Finally, we present some conclusions about the quality of the results obtained and the computational efficiency of the proposed implementation and suggest some topics for future developments.

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Hübner, scherer Fernando. "Topological optimization of shells with isogeometric analysis." Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAX105.

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Ce manuscrit présente des méthodes d'optimisation compatibles avec la conception assistée par ordinateur (CAO), avec emphase sur les coques de Reissner-Mindlin sous le paradigme de l'analyse isogéométrique (IGA). La principale contribution est un nouveau cadre pour l'optimisation topologique des coques épaisses courbes, non conformes, multi-patchs et trimées, soumises à des chargements externes.Cette méthode intègre la méthode des lignes de niveaux (LSM) avec une interface diffuse, une dérivée de forme de Hadamard et l'IGA multi-patch dans un algorithme de descente de gradient, permettant la capture systématique de l'évolution de la forme. Cette intégration permet la manipulation directe de géométries et de techniques d'analyse compatibles avec la CAO, ce qui permet d'obtenir des résultats sous forme de surface CAO.L'approche est appliquée à deux scénarios d'optimisation :(1) Minimisation de la compliance et du volume.(2) Optimisation pour réduction de contraintes. Une fonction de coût générale combinant deux stratégies est proposée. Premièrement, la p-norme de la contrainte de von Mises sert d'approximation de la contrainte maximale dans le domaine, ce qui constitue un moyen robuste et efficace de réduire la contrainte globalement en tenant compte des contributions de toutes les régions. Deuxièmement, une pénalisation locale des contraintes est mise en œuvre pour prévenir la défaillance, la fatigue et la plastification dans la phase matérielle, en veillant à ce que la contrainte de von Mises reste inférieure à la limite d'élasticité.La nouveauté de cette approche réside dans la modélisation de la fonction level set comme une surface NURBS, paramétrant des formes tridimensionnelles complexes à partir d'un domaine paramétrique en 2D. Cela permet d'identifier la distribution optimale du matériau sur la surface moyenne de la coque.Le matériau est modélisé sous l'hypothèse d'une petite déformation en élasticité linéaire à l'aide d'un modèle cinématique de coque de Reissner-Mindlin en contrainte plane.L'efficacité de notre approche est démontrée sur plusieurs géométries multi-patchs courbées, non conformes et découpées en 3D This manuscript presents CAD-compatible optimization methods focusing on Reissner-Mindlin shells within the isogeometric analysis (IGA) paradigm. The main contribution is a novel framework for topological shape optimization of curved, non-conforming multi-patch and trimmed thick shells subjected to external loads.This approach integrates the level set method (LSM) with a diffuse interface, a Hadamard shape derivative, and multi-patch IGA into a gradient descent algorithm, enabling the systematic capture of shape evolution. This integration allows for direct manipulation of CAD-compatible geometries and analysis techniques, ultimately yielding results as a CAD surface.The method is applied to two optimization scenarios:(1) Compliance and volume minimization.(2) Stress-Based Optimization. A general cost function is proposed that combines two strategies. First, the p-norm of the von Mises stress approximates the maximum stress in the domain, providing a robust and effective means of reducing stress globally by accounting for contributions from all regions. Secondly, a local penalization of the stresses is implemented to prevent failure, fatigue, and plastification in the material phase, ensuring that the von Mises stress remains below the yield stress.The novelty of this approach lies in modeling the level set function as a NURBS surface, parameterizing complex three-dimensional shapes from a 2D parameter domain. This allows for the identification of the optimal material distribution within the mid-surface of the shell.The material is modeled under a small strain assumption in linear elasticity using a Reissner-Mindlin kinematic shell model in plane stress.The effectiveness of our approach is demonstrated on several curved non-conforming and trimmed multi-patch geometries in 3D

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Enqvist, Per. "Spectral Estimation by Geometric, Topological and Optimization Methods." Doctoral thesis, Stockholm, 2001. http://media.lib.kth.se:8080/kthdisseng.html.

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LIMA, RICARDO OLIVEIRA DA CUNHA. "STRUT AND TIE MODELS THROUGH TOPOLOGICAL OPTIMIZATION TECHNIQUES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1407@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR Modelos de bielas e tirantes são, em última análise, representações discretas dos campos de tensão nos elementos estruturais de concreto armado próximos da ruptura e visam possibilitar um projeto consistente de todos os elementos estruturais. Este trabalho tem como objetivo desenvolver um programa de otimização topológica que gere e permita a visualização de um modelo de bielas e tirantes para elementos estruturais de concreto armado. O modelo gerado auxilia o engenheiro de projetos na compreensão dos caminhos de forças. Inicialmente o usuário deve ter como dado de entrada uma malha refinada em elementos finitos. A partir daí o programa calcula as tensões através da análise elástica por elementos finitos. As técnicas de otimização topológica usadas neste trabalho foram a do método da flexibilização súbita ( hard- kill method ) e a do método da remoção. No primeiro processo, os elementos com tensões baixas, que estão sendo usados ineficientemente têm seus módulos de elasticidade bruscamente reduzidos, enquanto que no método da remoção, estes elementos são retirados da malha. Tanto para modificar o módulo de elasticidade do elemento, quanto para retirar o elemento da malha, as tensões principais nos elementos são comparadas com uma tensão de referência definida como uma fração da maior tensão principal na malha. Caso essa tensão principal no elemento seja menor que a referida tensão de referência o elemento tem seu módulo de elasticidade modificado ou é eliminado conforme o método. A distribuição de tensão nos elementos é acompanhada pelo usuário através do módulo de visualização do programa e o processo de otimização topológica é repetido até que o critério de convergência imposto seja alcançado. Strut and tie models are ultimately discrete representations of the stress fields in the structural elements of reinforced concrete close to failure and they are meant to help the engineer to design a consistent project of all structural elements. This work aims to develop a program of topological optimisation that generates and allows the visualisation of a strut and tie model for structural elements of reinforced concrete. The generated model helps the project engineer to understand the load paths inside the element. Initially the user should have as data a refined finite element mesh. Starting from this point the program calculates the stress fields through a linear elastic finite element analysis. The techniques used for topological optimisation in this work are namely the hard-kill method and the method of removal. In the first process, the elements with low stress levels, that are not being used efficiently, have their elasticity modules abruptly reduced, while in the method of removal, these elements are removed from the mesh. Either to modify the elasticity module of the element or to remove the element from the mesh the principal stresses in each element are compared with a reference stress defined as a fraction of the largest principal stress in the mesh. If the principal stress in the element is smaller than this above mentioned reference stress the element has its elasticity module modified or is removed, depending on the method. The distribution of stresses in the elements can be followed by the user through the module of visualisation of the program and the process of topological optimisation is repeated until the specified convergence criterion is reached. Modelos de bielas y tirantes son, en último análisis, representaciones discretas de los campos de tensión de los elementos extructurales de concreto armado próximos a la ruptura. Su objetivo principal es ejecutar un proyecto que incluya todos los elementos extructurales. Este trabajo tiene como objetivo desarrollar un programa de optimización topológica que genere y permita la visualización de un modelo de bielas y tirantes para elementos extructurales de concreto armado. El modelo generado auxilia al ingeniero de proyectos en la comprensión de los caminos de fuerzas. Inicialmente el usuario debe tener como dato de entrada una malla refinada de elementos finitos. Así, el programa calcula las tensiones a través del análisis elástica por elementos finitos. Las técnicas de optimización topológica usadas en este trabajo fueron el método de la flexibilización súbita ( hard- kill method ) y el método de la remoción. En el primer proceso, los elementos con tensiones bajas, que están siendo utilizados ineficientemente tienen sus módulos de elasticidad bruscamente reducidos, mientras que en el método de la remoción, estos elementos son retirados de la malla. Tanto para modificar el módulo de elasticidad, cuanto para retirar el elemento de la malla, las tensiones principales en los elementos se comparan con una tensión de referencia definida como una fracción de la mayor tensión principal en la malla. En el caso en que esa tensión principal en el elemento sea menor que la tensión de referencia, el elemento tiene su módulo de elasticidad modificado o es eliminado conforme el método. El usuario acompaña la distribuición de tensión en los elementos a través del módulo de visualización del programa y el proceso de optimización topológica se repite hasta alcanzar el criterio de convergencia impuesto.

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Brodsky, Valery. "Optimization methods for topological design of interconnected ring networks." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/32594.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994. Includes bibliographical references (leaves 177-179). by Valery Brodsky. M.S.

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Luo, Fangyi. "Post-Layout DFM optimization based on hybrid encoded topological layout /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2005. http://uclibs.org/PID/11984.

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Du, Jia-Zheng. "Methods and software development for sectional and topological optimization of frame structures." Reims, 2004. http://theses.univ-reims.fr/exl-doc/GED00000024.pdf.

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Afin de satisfaire les besoins industriels en calcul et optimisation des structures, des méthodes de l'optimisation de section et de topologie de structures de poutre ont été étudiées et des logiciels pertinents basés sur ces méthodes ont été développés en utilisant les logiciels MSC/Patran-Nastran comme plate-forme. En combinant la méthode de critère d'optimalité et la méthode de programmation mathématique, différentes méthodes sont utilisées pour traiter les limitations avec différentes propriétés. Le modèle original de l'optimisation de section est transformé en un problème dual selon la théorie duale pour améliorer l'efficacité de résolution. La méthode de "Approximate Scaling Step" et la méthode d'Elimination des Limitations Négatives permettent d'accélérer la procédure d'optimisation. Basé sur la méthode ICM (Independent Continuous Mapping), un modèle de l'optimisation topologique utilisant les variables continues (entre 0 et 1 au lieu de 0 ou 1) est établi. Trois critères de convergence sont introduits pour obtenir rapidement et précisément la topologie optimale d'une structure. Pour ne pas éliminer les éléments ayant leur variable topologique nulle au cours de l'optimisation, la méthode de faible matériau est utilisée et comparée à la méthode de section minime. L'optimisation de topologie dans plusieurs cas de chargement est étudiée sous trois types de limitations : les limitations locales de contraintes, les limitations globales de déplacements et leur combinaison. Les méthodes ci-dessus ont été implantées dans les logiciels MSC/Patran&Nastran. Des exemples ont montré une amélioration importante de l'efficacité et de la précision dans l'optimisation de section et de topologie To satisfy the requirement on computation and optimization of frame structures in the engineering field, some sectional and topological optimization methods of frame structures are studied and a relevant software based on the present study is developed using the MSC/Patran&Nastran software as platform. Combining the optimality criteria method and the mathematical programming method, several methods are adopted to deal with the constraints with different properties. The original sectional optimization model is transformed into a dual problem according to the dual theory in order to reduce the number of the design variables so speed up the resolution. The methods of Approximate Scaling Step and Deletion of Negative Constraints also largely improve the efficiency. Based on the ICM (Independent Continuous Mapping) method, a topological optimization model with continuous topological variables (between 0 and 1 instead of 0 or 1) is built. In order to quickly and accurately obtain the optimum topological structures, three criteria are introduced and a self-adaptive algorithm is proposed. To deal with the elements with their null topological variable, the weak material method is proposed and compared with the tiny section method. The topological optimization for multi-loading cases is studied with three conditions: the local stress constraints, the global displacement constraints and their combination. According to the above methods, the MSC/Patran&Nastran software is secondly developed. The examples clearly show the notable improvement of the efficiency and accuracy

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Zhang, Fenghui. "Effective algorithms and protocols for wireless networking: a topological approach." Diss., Texas A&M University, 2008. http://hdl.handle.net/1969.1/86012.

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Much research has been done on wireless sensor networks. However, most protocols and algorithms for such networks are based on the ideal model Unit Disk Graph (UDG) model or do not assume any model. Furthermore, many results assume the knowledge of location information of the network. In practice, sensor networks often deviate from the UDG model significantly. It is not uncommon to observe stable long links that are more than five times longer than unstable short links in real wireless networks. A more general network model, the quasi unit-disk graph (quasi-UDG) model, captures much better the characteristics of wireless networks. However, the understanding of the properties of general quasi-UDGs has been very limited, which is impeding the design of key network protocols and algorithms. In this dissertation we study the properties for general wireless sensor networks and develop new topological/geometrical techniques for wireless sensor networking. We assume neither the ideal UDG model nor the location information of the nodes. Instead we work on the more general quasi-UDG model and focus on figuring out the relationship between the geometrical properties and the topological properties of wireless sensor networks. Based on such relationships we develop algorithms that can compute useful substructures (planar subnetworks, boundaries, etc.). We also present direct applications of the properties and substructures we constructed including routing, data storage, topology discovery, etc. We prove that wireless networks based on quasi-UDG model exhibit nice properties like separabilities, existences of constant stretch backbones, etc. We develop efficient algorithms that can obtain relatively dense planar subnetworks for wireless sensor networks. We also present efficient routing protocols and balanced data storage scheme that supports ranged queries. We present algorithmic results that can also be applied to other fields (e.g., information management). Based on divide and conquer and improved color coding technique, we develop algorithms for path, matching and packing problem that significantly improve previous best algorithms. We prove that it is unlikely for certain problems in operation science and information management to have any relatively effective algorithm or approximation algorithm for them.

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Caselli, Gabriele. "Some optimization problems in electromagnetism." Doctoral thesis, Università degli studi di Trento, 2022. http://dx.doi.org/10.15168/11572_343343.

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Electromagnetism and optimal control stand out as a topics that feature impactful applications in modern engineering, as well as challenging theoretical aspects of mathematical analysis. Within this context, a major role is played by the search of necessary and sufficient conditions characterizing optimal solutions, as they are functional to numerical algorithms aiming to approximate such solutions. In this thesis, three standalone topics in optimization sharing the underlying framework of Maxwell-related PDEs are discussed. First, I present an optimal control problem driven by a quasi-linear magneto-static obstacle problem featuring first-order differential state constraints. The non-linearity allows to suitably model electromagnetic waves in the presence of ferromagnetic materials, while the first-order obstacle is relevant for applications in the field of magnetic shielding. Existence theory and the derivation of an optimality system are addressed with an approximation technique based on a relaxation-penalization of the variational inequality. Second, I analyze an eddy current problem controlled through a dipole type source, i.e. a Dirac mass with fixed position and variable intensity: well-posedness of the state equation through a fundamental solution (of a curl curl - Id operator) approach and first order conditions are dealt with. To conclude, I discuss the computation of the topological derivative for shape functionals constrained to low-frequency electromagnetic problems (closely related to the eddy current model), with respect to the inclusion/removal of conducting material; the results are obtained using a Lagrangian approach and in particular the so-called averaged adjoint method. This approach requires the study of the asymptotic behavior of the solutions of some problems defined in the whole space, and the introduction and consequent analysis of appropriate function spaces.

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Mazoch, Jan. "Topologické optimalizace v technické praxi." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400688.

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Master’s thesis deals with an issue of 3D printing and of using a topological optimization for editing a shape of a 3D printed product. First part of this thesis provides a general description of a subtractive manufacturing technology, specifically its use in CNC milling machines, and of an additive manufacturing technology which is used in 3D printing. Second part of this thesis describes the topological optimization per se and specific methods which are used in the topological optimization. In the third and the fourth part of this thesis, topological optimization modules of software Ansys and SolidWorks are described. In the fifth part of this thesis, the topological optimization capabilities for 3D printed product on a specific embodiments of a design lightning and a cross-beam are demonstrated.

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Jia, David. "Topological interference management in clustered ad hoc networks." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPAST162.

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Cette thèse traite le problème de la gestion distribuée d'interférences dans les réseaux ad hoc clusterisés dans des canaux aléatoires. On suppose qu'un chef de cluster (CH) est sélectionné dans chaque groupe pour superviser les transmissions, l'allocation des ressources et des slots temporels.Pour opérer un réseau ad hoc clusterisé, il faut attribuer une bande de fréquence (FB en anglais) à chaque cluster. Lorsque le nombre de FBs disponibles est supérieur ou égal au nombre de cluster, il est facile d'effectuer une attribution orthogonale de FB, même de manière distribuée. Toutefois, pour les déploiements importants dans la pratique, en particulier dans les environnements militaires, le nombre de clusters est souvent beaucoup plus élevé que le nombre de FBs disponibles. Bien que la réutilisation spatiale des FBs puisse être utilisée dans ce cas, si la topologie du réseau le permet, une telle solution peut ne pas fournir des performances satisfaisantes dans certains scénarios (par exemple, une forte densité de clusters), et d'autres mécanismes sont alors nécessaires.Dans cette thèse, nous considérons que les clusters adjacents peuvent interférer entre eux et nous proposons d'utiliser une technique de gestion des interférences basée sur l'approche de la gestion des interférences topologiques (TIM en anglais). La méthode TIM classique nécessite la connaissance du graphe d'interférence du réseau, c'est-à-dire qu'il faut déterminer pour chaque récepteur si l'interférence induite par chaque autre nœud est faible ou forte dans des canaux déterministes. Des travaux antérieurs ont proposé d'étendre la méthode TIM aux canaux aléatoires en incorporant des informations statistiques sur l'état du canal (SCSI en anglais) dans l'algorithme.Toutefois, ces solutions présentent des performances mauvaises car elles sont moins performantes en termes de débit global et d'équité que l'accès multiple par répartition temporelle (TDMA en anglais). Par conséquent, dans ce contexte, la première contribution de cette thèse est d'améliorer l'état de l'art en proposant une autre extension du TIM, qui est appelée enhanced TIM (eTIM) dans cette thèse. Pour ce faire, nous fournissons une nouvelle méthode de gestion des interférences qui combine l'eTIM avec les accès TDMA et améliore à la fois le débit global et l'équité des débits.Pour appliquer cette solution, nous devons estimer le SCSI lié à chaque lien des grappes associées. Une solution triviale consiste à appliquer le TDMA, où chaque nœud transmet l'un après l'autre. Afin de réduire la durée de sensing, nous proposons deux nouvelles solutions d'ordonnancement qui utilisent des émissions simultanées et qui sont plus performantes que le TDMA. Cela constitue la deuxième contribution de cette thèse.Après la phase d'estimation, chaque nœud connaît le SCSI lié aux liens de tous les autres nœuds. Pour mettre en œuvre l'eTIM, les SCSI doivent être partagés entre les deux clusters. Nous avons donc étudié plusieurs méthodes de réduction de dimension, telles que l'analyse en composantes principales (linéaire) et l'autoencodeur (non linéaire), appliquées à la matrice des SCSI afin de réduire la quantité d'échanges de signalisation entre les clusters. Cela correspond à la troisième contribution de cette thèse This thesis addresses the problem of distributed interference management in clustered ad hoc networks under random fading channels. We assume that a cluster head (CH) is selected in each cluster to oversee transmissions, resource and time slots allocation.To operate a clustered ad hoc network, one needs to allocate a frequency band (FB) to each cluster. When the number of available FBs is greater or equal to the number of clusters, we can easily perform an orthogonal FB allocation, even in a distributed manner. However, for large deployments in practice, especially in military environments, the number of clusters is often much larger than the number of available FBs. While spatial FB reuse can be used in this case, if the network topology allows it, such a solution may not provide satisfactory performance in various scenarios (e.g. high cluster density), and other mechanisms are necessary.In this thesis, we consider that adjacent clusters can interfere between each other, and we propose to use an interference management technique based on the topological interference management (TIM) approach. The original TIM requires the knowledge of the interference graph of the network, i.e. determining for each receiver whether the interference caused by each other node is weak or strong in deterministic channels. Existing works have proposed to extend TIM in random channels by incorporating statistical channel state information (SCSI) in the algorithm.However, these solutions present poor performance since they achieve lower performance in terms of both sum rate and fairness than time-division multiple access (TDMA). Hence, in this context, the first contribution of this thesis is to improve the state-of-the-art by proposing another extension of TIM, that is referred to as enhanced TIM (eTIM) in this thesis. To this end, we provide a novel interference management method that combines eTIM with TDMA access and improves both the sum rate and the fairness.To apply this solution, we need to estimate the SCSI related to each link of the associated clusters. One trivial solution consists in applying TDMA, where each node transmits one after the other. In order to reduce the sensing duration, we propose two new scheduling solutions which use simultaneous transmissions and outperform TDMA. This constitutes the second contribution of this thesis.After the estimation phase, each node knows the SCSI related to the links from all the other nodes. To implement eTIM, the SCSI need to be shared between the two clusters. Thus, we investigated several dimensionality reduction methods, such as principal component analysis (linear) and autoencoder (non-linear), applied to the SCSI matrix in order to reducing the amount of signaling exchanges between clusters. This corresponds to the third contribution of this thesis

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Wei, Yuchen. "Reliability Analysis Method and Network Optimization of 5G Backhaul Network for Operators." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25483.

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Communication network reliability analysis is of great significance in the practice of network construction management and operation of telecom operators. It can provide an important scientific basis for the formulation of network construction strategy and the optimization and adjustment of network performance. Combining the theoretical results of reliability analysis with engineering application practice effectively in communication network operation has always been a research difficulty in communication network operation, which has high theoretical research value and market application prospect. This thesis work focuses on the improved network optimization method, discusses and extends the key technologies such as network topology, network model analysis index, network topology analysis method, calculation and analysis of evaluation results. Based on the classical network reliability analysis method, this thesis also does the following work, defines several main parameters that affect the network reliability analysis, puts forward the R-T (Ring-Tree) analysis method and the concept of branch line depth, and then finds out the approximate relationship between the branch line depth and network reliability through mathematical derivation. Finally, based on the theory proposed in this paper, a set of targeted network analysis tools is developed, and the proposed method is verified by using the local IP Bearer Network engineering data. The simulation results show that this method can quickly analyze the network reliability, significantly reduce the workload of data analysis, and give the targeted network optimization scheme. It can help the network operators to improve the network reliability quickly and effectively improve the network operation, management and maintenance ability of the operators.

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Macias, Diego. "Topological (Bio)Timber: An Algorithm and Data Approach to 3d Printing a Bioplastic and Wood Architecture." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491305462260965.

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Grelet, Vincent. "Rankine cycle based waste heat recovery system applied to heavy duty vehicles : topological optimization and model based control." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1006/document.

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L’évolution croissante du prix des carburants ainsi que les normes antipollution de plus en plus drastiques obligent les fabricants de véhicules commerciaux à développer des solutions innovantes pour réduire la consommation de carburant. Dans cet objectif, comme une grande partie de l’énergie contenue dans le carburant est directement relâchée à l’ambient sous forme de chaleur, celle-ci peut être valorisée et transformée via un cycle thermodynamique secondaire. Dans ce cadre, l’importante utilisation du cycle de Rankine à travers le monde en font un candidat naturel pour une implémentation dans un véhicule. Mais contrairement à une utilisation stationnaire, de nombreux obstacles se dressent pour une intégration totale dans un poids lourd. De nombreuses études ont été menées ces trente dernières années afin de déterminer le potentiel réel d’un tel système une fois embarqué à bord d’un véhicule. Les nombreuses sources de chaleur valorisables, les contraintes inhérentes à l’application embarquée ou encore les forts régimes transitoires induits par l’utilisation du camion doivent mener à une optimisation à la fois de l’architecture du système ainsi que de son système de contrôle. L’optimisation du système mène à un choix en terme de sources chaudes et froides, de topologie, de fluide de travail ainsi que de dimensionnement des composants afin de maximiser les performances. Le système de contrôle joue lui un rôle primordial afin de tirer un bénéfice maximum d’un tel système connaissant ses limites physiques ainsi que d’assurer une utilisation efficace. Dans cette thèse, une méthodologie de conception d’un système de valorisation des rejets thermiques est proposée. En se basant sur des simulations du véhicule complet basées sur un modèle détaillé, les thématiques de la sélection du fluide de travail, des sources chaudes et froides ainsi que l’optimisation des composants et du cycle sont approchées. Par la suite, le problème de contrôle en ligne de la surchauffe à la sortie de l’évaporateur est formalisé. En tenant compte des contraintes numériques d’implémentation, différentes stratégies de commande sont mises en place, allant du contrôleur PID à des structures plus avancées telle que la commande prédictive par modèle ou une loi de commande basée sur un observateur. La plupart de ces stratégies sont validées expérimentalement sur un banc d’essai mis en place durant la thèse The constant evolution of oil prices and the more and more stringent automotive emission standards force the original engine manufacturers to search for innovative solutions in order to reduce oil consumption. As an important part of the energy contained in the primary carrier (the fuel) is lost to the ambient through heat, it seems convenient to recover a part of this thermal energy and to turn it into fuel consumption reduction. Thermodynamic bottoming cycle such as the Rankine cycle could be used to meet this objective. Its popular use throughout the world for electricity generation makes it a natural candidate for on-board implementation in vehicles. However, a certain number of hurdles are still present before the system can be efficiently applied to heavy-duty trucks. In the last thirty years, numerous studies heave been carried out to evaluate the real potential of that kind of system on a vehicle but nothing has yet been commercialized. The heat sources to recover from, the constraints relative to the on-board application and the long and frequent transient behavior of the vehicle mean both the system architecture and its control strategy need to be optimized. The system optimization leads to a choice in terms of working fluid, heat sources and sinks, and components sizing in order to maximize power recovery and hence the fuel saving. The control plays a major role by using the capability of such a system to ensure an efficient and safe operation and limiting the interactions with the other vehicle sub-systems. In this thesis, a system design methodology is introduced to optimize the system architecture using complete model-based vehicle simulation. The constraints relative to the mobile application are taken into consideration to evaluate the potential of such a system. Modelbased control strategies for on controlled variable, namely the superheat level, are developed. Constrained by the implementation platform, different control frameworks ranging from PID to model predictive controllers or observer based controllers are developed to fit into a normal automotive electronic control unit. Most of these novel strategies were experimentally validated on a test rig developed during the thesis

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Bhela, Siddharth. "Load Learning and Topology Optimization for Power Networks." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/90407.

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With the advent of distributed energy resources (DERs), electric vehicles, and demand-response programs, grid operators are in dire need of new monitoring and design tools that help improve efficiency, reliability, and stability of modern power networks. To this end, the work in this thesis explores a generalized modeling and analysis framework for two pertinent tasks: i) learning loads via grid probing, and; ii) optimizing power grid topologies for stability. Distribution grids currently lack comprehensive real-time metering. Nevertheless, grid operators require precise knowledge of loads and renewable generation to accomplish any feeder optimization task. At the same time, new grid technologies, such as solar panels and energy storage units are interfaced via inverters with advanced sensing and actuation capabilities. In this context, we first put forth the idea of engaging power electronics to probe an electric grid and record its voltage response at actuated and metered buses to infer non-metered loads. Probing can be accomplished by commanding inverters to momentarily perturb their power injections. Multiple probing actions can be induced within a few tens of seconds. Load inference via grid probing is formulated as an implicit nonlinear system identification task, which is shown to be topologically observable under certain conditions. The analysis holds for single- and multi-phase grids, radial or meshed, and applies to phasor or magnitude-only voltage data. Using probing to learn non-constant-power loads is also analyzed as a special case. Once a probing setup is deemed topologically observable, a methodology for designing probing injections abiding by inverter and network constraints to improve load estimates is provided. The probing task under noisy phasor and non-phasor data is tackled using a semidefinite-program relaxation. As a second contribution, we also study the effect of topology on the linear time-invariant dynamics of power networks. For a variety of stability metrics, a unified framework based on the H2-norm of the system is presented. The proposed framework assesses the robustness of power grids to small disturbances and is used to study the optimal placement of new lines on existing networks as well as the design of radial topologies for new networks. Doctor of Philosophy Increased penetration of distributed energy resources such as solar panels, wind farms, and energy storage systems is forcing utilities to rethink how they design and operate their power networks. To ensure efficient and reliable operation of distribution networks and to perform any grid-wide optimization or dispatch tasks, the system operator needs to precisely know the net load (energy output) of every customer. However, due to the sheer extent of distribution networks (millions of customers) and low investment interest in the past, distribution grids have limited metering infrastructure. Nevertheless, data from grid sensors comprised of voltage and load measurements are readily available from a subset of customers at high temporal resolution. In addition, the smart inverters found in solar panels, energy storage units, and electric vehicles can be controlled within microseconds. The work in this thesis explores how the proliferation of grid sensors together with the controllability of smart inverters can be leveraged for inferring the non-metered loads i.e., energy output of customers that are not equipped with smart inverters/sensors. In addition to the load learning task, this thesis also presents a modeling and analysis framework to study the optimal design of topologies (how customers are electrically inter-connected) for improving stability of our power networks.

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Noguchi, Yuki. "An optimum structural design methodology for acoustic metamaterials using topology optimization." Kyoto University, 2019. http://hdl.handle.net/2433/242492.

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Van, Bussel Frank [Verfasser], Marc [Akademischer Betreuer] Timme, Annette [Akademischer Betreuer] Zippelius, and Fred [Akademischer Betreuer] Wolf. "Topological Optimization in Network Dynamical Systems / Frank Van Bussel. Gutachter: Marc Timme ; Annette Zippelius ; Fred Wolf. Betreuer: Marc Timme." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2011. http://d-nb.info/1042304874/34.

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Avgin, Murat Atacan. "Evolutionary Structural Optimization Of Multiple Load Case Generic Aircraft Components." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614973/index.pdf.

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Structural optimization is achieving the best objective function from a predefined medium, well bounded by constraints. Optimization methods have been utilized on different engineering applications to minimize the conceptual design effort that creates the necessity of new optimization techniques. Evolutionary Structural Optimization (ESO) is a topological optimization algorithm, which is defined as removing of inefficient elements from a design domain. ESO stress based method is applied to linear elastic, isotropic aircraft components for multiple load case. The bulk structure is modeled and discretized into three dimensional solid hexahedron or tetrahedron mesh, afterwards constraints, load and boundary conditions are defined in MSC.PATRAN. MSC.NASTRAN is utilized as finite element solver. The stress results are collected and evaluated by program developed in MICROSOFT VISUAL BASIC. The elements which are below the stress limit are eliminated. The remaining elements are operated after increasing the stress limit. The iteration process continued until prescribed rejection ratio is reached. Well known examples in literature are solved using program code and similar results are obtained which is a check for the code developed. Four generic aircraft components, the clevis, the lug, the main landing fitting and power control unit fitting were structurally optimized. The stress distribution in optimized results and existing aircraft designs are compared.

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Vála, Pavel. "Optimalizace vlastností snímače vektoru kontaktní síly." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228264.

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The aim of this work is an optimalization of vector contact force sensor properties which prototype is at the moment designed. The principle of sensor is based on transformation active part of sensor using three tensiometers and following value indentification of loading force vector using neuron network. Sensor has a bad sensitivity when axis force load or near to axis of sensor. To solve this problem ''MKP'' model of sensor was used on which suitable optimalization method was applicated. From the result of optimalization modificated sensor will be proposed and will be made a utility verification using neuron network.

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Santos, Renatha Batista dos. "Otimização topológica estrutural baseada em confiabilidade com restrição em tensão e projeto de estruturas sujeitas a condição de contato unilateral." Laboratório Nacional de Computação Científica, 2017. https://tede.lncc.br/handle/tede/253.

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Submitted by Maria Cristina (library@lncc.br) on 2017-05-02T18:47:49Z No. of bitstreams: 1 Tese_Machado.pdf: 522761 bytes, checksum: 871b43ac7f8d7aae60a30b8371cf5898 (MD5) Approved for entry into archive by Maria Cristina (library@lncc.br) on 2017-05-02T18:47:59Z (GMT) No. of bitstreams: 1 Tese_Machado.pdf: 522761 bytes, checksum: 871b43ac7f8d7aae60a30b8371cf5898 (MD5) Made available in DSpace on 2017-05-02T18:48:08Z (GMT). No. of bitstreams: 1 Tese_Machado.pdf: 522761 bytes, checksum: 871b43ac7f8d7aae60a30b8371cf5898 (MD5) Previous issue date: 2017-02-09 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes) In structural optimization, the obtained results must be robust in relation to uncertainties, whether they arise from the probabilistic nature of the variables or those inherent to the resistance of the materials, for example. Traditionally, uncertainties in structural design were taken into account by using safety factors. Nevertheless, it is well known that the safety factor approach can be limited in a wide variety of cases or yields to conservative designs. For this reason, several authors proposed different approaches to address optimization problems subject to uncertainties, such as robust topology optimization and reliability-based topology optimization. In this work, we present an alternative approach for robust topology optimization considering a point-wise worst case scenario. We also study reliability-based structural topology optimization problem under stress constraints. In addition, in order to apply an approach for uncertainty based optimization into a non-linear problem, we investigate the deterministic structural topology optimization problem subject to unilateral contact condition. Em otimização estrutural os resultados obtidos devem ser robustos em relação a incertezas, sejam elas oriundas da natureza probabilística das variáveis de trabalho ou àquelas inerentes à resistência dos materiais, por exemplo. Classicamente, levar em conta incertezas em um projeto de estruturas significa utilizar um fator de segurança. No entanto, tal abordagem pode ser bastante restritiva em uma grande variedade de casos ou ainda conduzir a resultados muito conservadores. Este fato tem levado ao desenvolvimento de diferentes metodologias de otimização estrutural tais como otimização robusta e otimização baseada em confiabilidade. Neste trabalho objetiva-se apresentar uma abordagem alternativa para o problema de otimização robusta de estruturas levando em consideração otimização no pior cenário, além de estudar o problema de otimização topológica estrutural baseada em confiabilidade com restrição em tensão. Além disso, a fim de aplicar técnicas de otimização considerando incertezas num problema não linear é estudado o problema determinístico de otimização topológica de estruturas sujeitas a condição de contato unilatera

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Pastrnková, Markéta. "Návrh konstrukce nové verze vozíku a dokovací stanice pro kanálové regály." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443771.

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The master's thesis deals with the analysis of the current version of the trolley and the docking station of the channel racks and the design of modifications. The theoretical part describes the components of the storage channel system. There is also explained principle of pallet storage in this part. In the following chapter, several variants of the design of the lifting mechanism of the lifting platform are elaborated. The work also presents static structural analysis of the current version of the trolley and docking station, parametric study and topological optimization of one of the components. Static structural analyzes were partially solved in the finite element software RFEM by Dlubal Software s.r.o company, and mainly in the software ANSYS Workbench 2020 R2 by ANSYS, Inc. company.

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Lopes, Cinthia Gomes. "Síntese de mecanismos flexíveis com restrição em tensão e otimização topológica de estruturas sujeitas a contato e atrito." Laboratório Nacional de Computação Científica, 2017. https://tede.lncc.br/handle/tede/258.

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Submitted by Maria Cristina (library@lncc.br) on 2017-05-04T14:31:04Z No. of bitstreams: 1 CinthiaLopesTeseVersaoFinal.pdf: 1204191 bytes, checksum: b3284e9c8c1229fa89ebac50ffc465ba (MD5) Approved for entry into archive by Maria Cristina (library@lncc.br) on 2017-05-04T14:31:14Z (GMT) No. of bitstreams: 1 CinthiaLopesTeseVersaoFinal.pdf: 1204191 bytes, checksum: b3284e9c8c1229fa89ebac50ffc465ba (MD5) Made available in DSpace on 2017-05-04T14:31:23Z (GMT). No. of bitstreams: 1 CinthiaLopesTeseVersaoFinal.pdf: 1204191 bytes, checksum: b3284e9c8c1229fa89ebac50ffc465ba (MD5) Previous issue date: 2017-01-23 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes) The topological derivative was rigorously defined by Sokolowski and Zochowski in 1999. Since then it has been shown as an important tool for solving different kind of problems such as: topology optimization, inverse problems, image processing, multiscale constitutive modeling, fracture mechanics sensitivity analysis, damage evolution modeling and contact problems sensitivity analysis. The topological derivative is obtained from the asymptotic analysis of classic solutions to boundary value problems in singularly perturbed domain, together with asymptotic analysis of shape functionals with respect to the parameter that governs the size of the topological perturbation. In this work, the topological derivative concept is applied in the context of compliant mechanisms design with stress constraints and topology optimization of structures subject to contact condition and given friction. Compliant mechanisms are mechanical devices composed by one single peace that transforms simple inputs into complex movements by amplifying and changing their direction. Hence they are easy to manufacture at a very small scale such microtools has been applied in different contexts including microsurgery, cell manipulation and nanotechnology processing. In this work, a new approach based on the topological derivative concept to deal with the design of compliant mechanisms is proposed. This approach consists in introducing a von Mises stress constraint to the problem which naturally avoids hinges and provides mechanisms that satisfy resistance and functionality criteria. Contact problems are naturally nonlinear and their main difficult comes out from the fact that the effective contact area is not known a priori. Since the problem is non-linear, the domain decomposition technique together with the Steklov-Poincaré pseudo-differential boundary operator are used for asymptotic analysis purposes with respect to the small parameter associated with the size of the topological perturbation. As a fundamental result, the expansion of the strain energy coincides with the expansion of the Steklov-Poincar\' operator on the boundary of the truncated domain, leading to the associated topological derivative. Finally, the obtained result is applied in a case study that consists in the topology optimization of an eyebar belonging to an eyebar-chain of the Hercílio Luz Bridge in Florianópolis - SC, Brazil. A derivada topológica foi rigorosamente definida por Sokolowski e Zochowski em 1999 e, desde então, tem se mostrado uma importante ferramenta para o tratamento de diferentes problemas, dentre os quais destacam-se: otimização topológica, problemas inversos, processamento de imagens, modelagem constitutiva multiescala, análise de sensibilidade à fratura mecânica, modelagem de evolução de dano e análise de sensibilidade para problemas de contato. A derivada topológica é obtida a partir da análise assintótica de soluções clássicas para problemas de valores de contorno em domínios singularmente perturbados, combinada com a análise assintótica de funcionais de forma com relação ao parâmetro que governa o tamanho da perturbação. Neste trabalho, o conceito de derivada topológica é aplicado no contexto de síntese de mecanismos flexíveis com restrição em tensão e otimização topológica de estruturas sujeitas a condição de contato unilateral e atrito dado. Mecanismos flexíveis são estruturas mecânicas compostas por apenas uma peça (estruturas monolíticas) capazes de transformar uma dada força de entrada em um movimento de saída, de acordo com a resposta desejada. Devido à facilidade de produção em escalas milimétricas ou até micrométricas, este tipo de estrutura tem sido utilizada em diferentes aplicações, tais como microcirurgia, manipulação de células, circuitos microeletrônicos. No presente trabalho, uma nova abordagem baseada no conceito de derivada topológica é proposta para tratar o problema de otimização topológica de mecanismos flexíveis. Esta abordagem consiste em introduzir uma restrição na tensão de von Mises ao problema, o que elimina o surgimento de juntas flexíveis, conduzindo a mecanismos que atendem simultaneamente aos critérios de resistência e funcionalidade. Problemas que envolvem condição de contato são naturalmente não lineares e sua principal dificuldade está em não se conhecer, a priori, a área de efetivo contato. Por conta de sua natureza não linear, a técnica de decomposição de domínio em conjunto com o operador pseudo-diferencial Steklov-Poincaré são utilizados para fins de análise assintótica com respeito ao parâmetro que governa o tamanho da perturbação topológica. Como resultado fundamental, a expansão da energia de deformação coincide com a expansão do operador Steklov-Poincaré sobre a fronteira do domínio fictício, o que conduz à derivada topológica associada. Finalmente, este resultado é aplicado em um estudo de caso que consiste na otimização topológica de um olhal pertencente a uma cadeia de olhais da Ponte Hercílio Luz, localizada em Florianópolis - SC.

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Mesquita, Gustavo Henrique Jesus. "Otimização topológica de absorvedores dinâmicos de vibrações sujeito a vibração livre e forçada." Universidade Federal de Goiás, 2016. http://repositorio.bc.ufg.br/tede/handle/tede/6283.

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Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-27T13:23:56Z No. of bitstreams: 2 Dissertação - Gustavo Henrique Jesus Mesquita - 2016.pdf: 1893414 bytes, checksum: b18598c3179586967bc12f642386c3f1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-27T13:24:18Z (GMT) No. of bitstreams: 2 Dissertação - Gustavo Henrique Jesus Mesquita - 2016.pdf: 1893414 bytes, checksum: b18598c3179586967bc12f642386c3f1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Made available in DSpace on 2016-09-27T13:24:18Z (GMT). No. of bitstreams: 2 Dissertação - Gustavo Henrique Jesus Mesquita - 2016.pdf: 1893414 bytes, checksum: b18598c3179586967bc12f642386c3f1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-08-29 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES The aim of this work is to propose a methodology of application of the FEM and topology optimization technique as tools of analysis and optimal design of mechanical systems subject to natural and forced vibrations in order to reach the optimal geometry of a dynamic absorbing of vibrations. It presents the mathematical reasoning and develop a program in Matlab® that implements the topology optimization technique will be employed to generate the optimal material distribution ( layout ) continuous mechanical systems without external excitation and subject to harmonic forces with preset frequency. Propõe-se uma metodologia de aplicação do MEF (Método dos Elementos Finitos), juntamente com uma técnica de otimização topológica como ferramenta de análise e projeto ótimo de sistemas mecânicos sujeitos a vibração forçada. Em particular, chega-se à geometria ótima de um absorvedor dinâmico de vibrações contínuo. Apresenta-se a modelagem matemática, além de se desenvolver um código em Matlab® que implementa a técnica de otimização topológica por distribuição de material aplicado a sistemas mecânicos contínuos com excitação externa e harmônica de tal forma que a menor frequência natural seja predefinida.

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Pereira, Carlos Eduardo Leite 1975. "Analise de sensibildade topologica em problemas de não-linearidade geometrica e hiperelasticidade não-linear quasi-incompressivel." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263455.

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Orientador: Marco Lucio Bittencourt Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica Made available in DSpace on 2018-08-06T20:24:00Z (GMT). No. of bitstreams: 1 Pereira_CarlosEduardoLeite_D.pdf: 2868659 bytes, checksum: 90d7fda0b66989796767d36726984af4 (MD5) Previous issue date: 2006 Resumo: No presente trabalho, tem-se como objetivo realizar a otimizacao topológica em problemas de elasticidade envolvendo não-linearidade geométrica (grandes deslocamentos e rotações) e não-linearidade de material, no caso, hiperelasticidade não-linear quasi-incompressível, aplicando o conceito de Análise de Sensibilidade Topológica (AST) através de uma formulação Lagrangiana total. A AST é caracterizada por uma função escalar, denominada Derivada Topológica, que fornece para cada ponto do domínio de definição do problema a sensibilidade de uma determinada função quando um pequeno furo é criado no domínio. Assim, considerando a impossibilidade em se obter uma solução analítica para os problemas considerados no presente trabalho, uma expressão aproximada da Derivada Topológica é obtida através de uma análise assintótica numérica para o problema envolvendo somente não-linearidade geométrica e posteriormente para o problema envolvendo hiperelasticidade não-linear quasi-incompressível. Resultados numéricos para ambos os tipos de problema e as limitações quanto à aplicabilidade da Derivada Topológica aproximada obtida para tais problemas são apresentados Abstract: The aim of the present work is to optimize the topology of elasticity problems with geometric nonlinearities (large displacement and rotation) and material nonlinearities, in this case, nonlinear nearly-incompressible hyperelasticity applying the concept of Topological Sensitivity Analysis (TSA) and a total Lagrangian formulation. The TSA results in a scalar function, denominated Topological Derivative, that gives for each point of the domain the sensitivity of a given cost function when a small hole is created. As an analytical solution is impossible for the considered problems in the present work, an approximated expression for the Topological Derivative is obtained by numerical asymptotic analysis first for geometric nonlinearities and after for nonlinear nearly-incompressible hyperelasticity. Numerical results for both problems and the limitations of the approximated Topological Derivative are presented. Doutorado Mecanica dos Sólidos e Projeto Mecanico Doutor em Engenharia Mecânica

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Morretton, Elodie. "Une démarche de conception de pièces légères pour la fabrication additive basée sur l'optimisation topologique." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI017.

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Les procédés de fabrication additive sont en pleine essor ces dernières années. De nombreux industriels cherchent à évaluer leur potentiel et leurs avantages. Ces nouvelles technologies impliquent des changements au niveau des manières de fabriquer mais également au niveau des manières de concevoir. Ce travail de thèse s’est intéressé à ce second aspect et apporte plus particulièrement des réponses à la question de recherche suivante :Quel guide méthodologique suivre pour une étude dont le but est de reconcevoir des pièces afin de s’approcher de l’optimum en termes de masse ?Pour traiter cette question, le problème a été abordé au regard de plusieurs questions sous-jacentes afin de combler les manques identifiés dans l’état de l’art réalisé que ce soit sur les problématiques du paramétrage de l’optimisation topologique ou sur celles des techniques de reconstruction. Nous avons réalisé plusieurs études de cas afin de pouvoir répondre à ces différentes questions et pouvoir ainsi lister les points critiques. Ce travail de thèse a été réalisé en partenariat avec un acteur de l’aéronautique : Zodiac Seats France. Ceci nous a permis de réaliser des études de cas sur des pièces existantes qui possédaient un certain niveau de complexité. Parmi ces études de cas, nous avons distingué deux types d’étude :- Une étude élémentaire pour effectuer des boucles rapides en faisant varier les choix et- Une série d’études industrielles pour regarder s’il y a convergence ou divergence entre les conclusions de l’étude élémentaire et des cas d’applications plus complexes.Puis, nous avons donné une description détaillée d’une méthode de conception pour la fabrication additive basée sur 5 grandes phases :- l’évaluation de la pièce candidate ou des pièces,- la modélisation,- l’optimisation topologique : obtention d’une forme de géométrie,- la reconstruction de la pièce à partir du résultat de l’optimisation topologique et intégration des contraintes de fabrication- l’optimisation dimensionnelle : affiner les dimensions de la géométrie reconstruite.A ces phases, viennent s’ajouter des étapes de contrôle via des analyses éléments finis. Cette démarche s’est construite autour d’observations faites lors du déroulement des études de cas. Pour chacune de ces phases, un ensemble de recommandations a été défini pour aider le concepteur dans l’obtention d’une pièce optimale en termes de masse. Enfin, nous avons donné ce descriptif de la méthode à un concepteur relativement novice pour avoir un nouveau regard sur celle-ci et pouvoir ainsi identifier des points à améliorer. A l’issue de ce travail de conception, ce concepteur a pointé plusieurs points manquants ainsi que plusieurs faiblesses dans l’argumentaire du guide méthodologique. Ses observations et son opinion, nous ont permis de prendre du recul vis-à-vis de notre travail.Les apports majeurs de ce travail de thèse sont :- La description détaillée d’une méthode composée de 5 grandes phases- Dans cette démarche, nous avons dénombré plusieurs étapes clés : une étape préliminaire d’évaluation du potentiel des pièces à reconcevoir au regard de la fabrication additive et plusieurs phases d’optimisation complémentaires (topologie et dimensions),- La mise en avant de l’importance de bien délimiter le périmètre de l’étude (pièce isolée ou dans le mécanisme),- L’identification des étapes au cours desquelles les contraintes de fabrication devront être intégrées- Le positionnement du concepteur au cœur de la méthode : les outils numériques permettent de ne réaliser qu’une partie du travail de conception Additive manufacturing processes have been growing in recent years. Many industries seek to assess their potentials. These new technologies involve changes in terms of manufacturing but also in terms of designing. This work is interested in this second aspect. It brings answers to the following research question:What methodological guide to follow for a study whose goal is to redesign pieces in order to approach the optimum in terms of mass?To answer to this question, the problem is decomposed into several sub questions. These questions must fill the identified lacks in the state of the art, and deal with topological optimization parameters or reconstructions techniques for example. Several case studies are realized to answer to these sub questions and to list the critical points. This work is realized in partnership with an aerospace company: Zodiac Seats France. This allowed us to work on existing parts which have a certain complexity level. Two types of studies can be distinguished:- Basic study: to experiment different strategies and to make variation on the parameter choices rapidly.- Practical study: to check on more complex cases if there is a convergence with basic study conclusions.Then, a detailed description of a design method for additive manufacturing is provided. It is composed in 5 phases:- Evaluation of parts potential.- Model of parts.- Optimization of parts with topological optimization tools: obtaining the shape of the parts.- Reconstruction of parts from the topological result: integration of manufacturing constraints.- Optimization of reconstructed parts with dimensional optimization tools: refinement of the dimensions of reconstructed parts.Between these phases, checked step are added, based on finite element analysis. This method is built on practical observations obtained from the different case studies. For each phase, a set of recommendations is provided to help designers to design lightweight parts. Finally, this descriptive method is given to a novice designer to have the method tested. The aim of this test is having a new vision on this detailed method and identifying points to be improved. At the achievement of this design work, the designer noticed several missing points as well as several weaknesses in the method argument. His observations and his opinions gave us to take a step back from our work.The major contributions of this work are:- The description of a detailed method in 5 large phases.- In this method, there are several key steps : 1 step of evaluation of parts potential with regard to additive manufacturing as well as two complementary steps of optimization (shape and dimensions)- The perimeter of the parts study must be delimited clearly (isolated parts or in the mechanism),- The identification of the stages in which the manufacturing constraints have to be integrated- The position of the designer to the method heart: digital tools realize only one part of the design work

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Yago, Llamas Daniel. "A new computational approach to topology optimization in solid mechanics problems." Doctoral thesis, Universitat Politècnica de Catalunya, 2022. http://hdl.handle.net/10803/673572.

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This doctoral thesis addresses topology optimization problems at a single scale. Based on this purpose, a new topology optimization approach is developed in order to improve existing and widespread techniques in the research community on the topic. The proposed technique presents several characteristics that overcome some of the well-known difficulties in topological optimization while maintaining a considerable degree of simplicity. In the first place, the formulation of the topological optimization technique is presented, as well as its algorithm. The method is based on 4 fundamental features: (1) the use of a 1-0 characteristic function, as well as the precise identification of the material boundaries from a discrimination function (0-level-set function), (2) the definition of a topological derivative consistent with the ersatz method (used in the state problem), as an approximation to the exact topological derivative, (3) the inclusion of a Laplacian regularization with minimum size control of the different components, and (4) the formulation of an analytical optimality condition aiming at the optimal topology solution. The approach is applied to different topology optimization problems, well-reported in the literature and used as numerical benchmarks (in structural and thermal problems), to examine their performance. In these fields, stiffness and conductivity maximization problems are considered for validation, respectively. In addition, different topological optimization problems of major engineering interest are tackled, including the design of compliant mechanisms within the structural field and thermal cloaking devices within the thermal field. Finally, a comparison of the formulation with other existing topology optimization techniques is performed, including (1) SIMP, (2) ESO/BESO, and (3) Level-set with Hamilton-Jacobi as the updating equation. The analysis of the results provides a comparison in terms of the quality of the topology of each method, the computational cost of the optimal solutions, as well as the simplicity of implementation. The resulting study reveals the potential of the developed methodology in these specific comparison terms. In an attempt to bring the method closer to other researchers and to promote its use, an educational version of the method (written in MATLAB) has been published in an online repository, together with documentation, facilitating its dissemination and subsequent use in other applications of interest. El objetivo de esta tesis doctoral es abordar el problema de optimización topológica a una única escala. En base a este propósito, se desarrolla una nueva técnica de optimización capaz de competir con técnicas ya existentes y extendidas entre la comunidad investigadora sobre el tema. Esta técnica presenta características que superan algunas de las dificultades bien conocidas en optimización topológica manteniendo un buen grado de simplicidad. En primer lugar, se presenta la formulación de la técnica de optimización topológica, así como su algoritmia. El método se fundamenta en 4 aspectos básicos: (1) la utilización de una función característica 1-0, así como la definición precisa de las fronteras materiales a partir de una función de discriminación (isonivel 0 de la función level-set), (2) la definición de una derivada topológica coherente con el método ersatz (utilizado en la ecuación de estado), como aproximación a la derivada topológica exacta, (3) la inclusión de una regularización Laplaciana con control de tamaño mínimo de los diferentes componentes, y (4) la definición de una condición de optimalidad analítica para la determinación de la solución óptima de la topología. La metodología se aplica a diferentes problemas de optimización topológica bien detallados en la literatura y utilizados como ensayos numéricos para examinar su respuesta frente a problemas estructurales y térmicos. En estos campos, se incluyen problemas de maximización de la rigidez y de la conductividad, respectivamente. Además, se resuelven diferentes problemas de optimización topológica con gran interés ingenieril en los campos estructurales con el diseño de mecanismos y térmicos con el diseño de dispositivos de camuflaje térmicos. Finalmente, se realiza una comparación de la formulación con otras técnicas ya existentes, por ejemplo: (1) SIMP, (2) ESO/BESO, y (3) Level-set con Hamilton-Jacobi como ecuación de evolución. El análisis de los resultados permite comparar la calidad de la topología de cada método, el coste computacional de las soluciones óptimas, así como la simplicidad de implementación, demostrando el potencial de la metodología desarrollada principalmente en estos términos de comparación. Con la finalidad de acercar el método a otros investigadores y de promover su utilización, se ha publicado una versión educativa del mismo (en MATLAB) en un repositorio online, junto a documentación, permitiendo así la divulgación del mismo y la posible utilización en otras aplicaciones de interés. Enginyeria mecànica, fluids i aeronàutica

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Teves, André da Costa. "Otimização de acelerômetros MEMS eletroestáticos de alto desempenho." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-01082013-144527/.

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Microssistemas eletromecânicos ou Micro-Electro-Mechanical Systems (MEMS), representam uma classe de dispositivos que combinam funções mecânicas e eletrônicas em escala micrométrica. Através do uso de técnicas de microfabricação, adaptadas da indústria de semicondutores, é realizada a integração entre estruturas móveis, sensores, atuadores e eletrônica, tornando possível a implementação de sistemas completos miniaturizados. Acelerômetros eletrostáticos estão entre os dispositivos MEMS mais comercializados hoje em dia, com venda anual em todo o mundo superior a 100 milhões de unidades e crescente a cada ano. Eles são geralmente fabricados utilizando-se três lâminas de silício espessas, coladas uma sobre a outra. A camada intermediária é obtida por processos de corrosão e consiste de uma grande massa de prova suspensa por uma ou mais vigas. Ela é separada das lâminas superior e inferior por um pequeno espaço vazio (gap), dando origem a dois conjuntos de capacitores de placas paralelas. A flexibilidade das vigas permite que a massa se mova proporcionalmente à aceleração externa e o seu deslocamento é estimado pela variação da capacitância do conjunto. O projeto destes sensores é uma tarefa complexa, já que os seus diversos requisitos de desempenho são, na maioria das vezes, conflitantes, isto é, se o projeto é modificado para melhorar uma característica, as demais são inevitavelmente afetadas e por isso técnicas de otimização devem ser utilizadas na etapa de projeto. Com o intuito de melhorar o desempenho de micro-acelerômetros capacitivos, são então propostas e avaliadas no atual trabalho duas técnicas de otimização distintas, sendo uma delas baseada em Otimização Paramétrica (OP) e a outra no Método da Otimização Topológica (MOT). A OP parte de uma topologia previamente definida e adota algumas de suas características geométricas como variáveis de projeto. Para levar em consideração incertezas nas dimensões e propriedades dos materiais, que é um elemento-chave na concepção e fabricação de dispositivos MEMS, neste trabalho a OP é combinada com o método da Otimização de Projeto Baseado em Confiabilidade ou Reliability-based Design Optimization (RBDO). Análises de confiabilidade de primeira ordem através do Método de Confiabilidade de Primeira Ordem, ou First-Order Reliability Method (FORM), são utilizadas para o cálculo das probabilidades envolvidas nesta formulação. Já o MOT combina o Método dos Elementos Finitos (MEF) e um modelo de material com algoritmos de otimização para encontrar a distribuição ótima de material em um domínio de projeto pré-estabelecido. As variáveis de projeto são as pseudo-densidades que descrevem a quantidade de material em cada ponto do domínio. Na modelagem pelo MEF utiliza-se elementos de placa estrutural do tipo Mixed Interpolation of Tensorial Components (MITC). Exemplos práticos utilizando ambas as abordagens são apresentados e os seus resultados discutidos com o intuito de se avaliar o potencial de cada técnica para o projeto de micro-acelerômetros capacitivos. Micro-Electro-Mechanical Systems (MEMS) are a class of devices that combine mechanical and electronic functions on a micrometric scale. Through the use of microfabrication techniques, adapted from the semiconductor industry, the integration of mobile structures, sensors, actuators and electronics is performed, allowing the implementation of fully miniaturized systems. Electrostatic accelerometers are among the highest volume MEMS products nowadays, with worldwide annual sales topping 100 million units and growing steadily. Bulk-type accelerometers are generally manufactured using three thick silicon wafers, bonded together one on top of the other. The intermediate layer is obtained by etching processes and consists of a big proof mass suspended by one or more beams. It is separated from the upper and lower wafers by a small gap, resulting in two sets of parallel plate capacitors. The flexibility of the beams allows the mass to move proportionally to the external acceleration and its displacement is estimated by the change in capacitance of the set. The design of such sensors is a complex task, since they depend on many performance requirements, which are most often conflicting. If a design is modified to improve one characteristic, others are inevitably affected. Therefore, optimization techniques are regularly used in the design stage of MEMS sensors. Aiming to improve the performance of capacitive micro-accelerometers, in the present work two optimization techniques are presented, the first is based on Parametric Optimization (PO) and the other is the Topology Optimization Method (TOM). The PO starts from a predefined topology and uses some of its geometric characteristics as design variables. In order to account for uncertainties in the dimensions and material properties, which is a key element in the design and fabrication of MEMS devices, in this work the PO is combined with the Reliability-based Design Optimization (RBDO) method. The First-Order Reliability Method (FORM) is applied to calculate the probabilities involved in the RBDO formulation. The TOM combines the Finite Element Method (FEM) and a material model with optimization techniques to find the best constrained material distribution in a fixed design domain. The design variables are the pseudo-densities that describe the amount of material at each point of the domain. The FE model is discretized using the Reissner-Mindlin plate element with the Mixed Interpolation of Tensorial Components (MITC) formulation. Practical examples using both approaches are presented and discussed in order to evaluate the potential of each technique to the design of capacitive micro-accelerometers.

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Karliczek, Martin. "Elements of conditional optimization and their applications to order theory." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2014. http://dx.doi.org/10.18452/17085.

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In dieser Arbeit beweisen wir für Optimierungsprobleme in L0-Moduln relevante Resultate und untersuchen Anwendungen für die Darstellung von Präferenzen. Im ersten Kapitel geht es um quasikonkave, monotone und lokale Funktionen von einem L0-Modul X nach L0, die wir robust darstellen. Im zweiten Kapitel entwickeln wir das Ekeland’sche Variationsprinzip für L0-Moduln, die eine L0-Metrik besitzen. Wir beweisen eine L0 -Variante einer Verallgemeinerung des Ekeland’schen Theorems. Der Beweis des Brouwerschen Fixpunktsatzes für Funktionen, die auf (L0)^d definiert sind, wird in Kapitel 3 behandelt. Wir definieren das Konzept des Simplexes in (L0)^d und beweisen, dass jede lokale, folgenstetige Funktion darauf einen Fixpunkt besitzt. Dies nutzen wir, um den Fixpunktsatz auch für Funktionen auf beliebigen abgeschlossenen, L0 -konvexen Mengen zu zeigen. Eine allgemeinere Struktur als L0 ist die bedingte Menge. Im vierten Kapitel behandeln wir bedingte topologische Vektorräume. Wir führen das Konzept der Dualität für bedingte Mengen ein und beweisen Theoreme der Funktionalanalysis darauf, unter anderem das Theorem von Banach-Alaoglu und Krein-Šmulian. Im fünften Kapitel widmen wir uns der Darstellung mit wandernden konvexen Mengen. Wir zeigen danach, wie die Transitivität für diese Darstellungsform beschrieben werden kann. Abschließend modellieren wir die Eigenschaft, dass die Transitivität einer Relation nur für ähnliche Elemente gesichert ist und diskutieren Arten der Darstellung solcher Relationen. In this thesis, we prove results relevant for optimization problems in L0-modules and study applications to order theory. The first part deals with the notion of an Assessment Index (AI). For an L0 -module X an AI is a quasiconcave, monotone and local function mapping to L0. We prove a robust representation of these AIs. In the second chapter of this thesis, we develop Ekeland’s variational principle for L0-modules allowing for an L0-metric. We prove an L0-Version of a generalization of Ekeland’s theorem. A further application of L0 -theory is examined in the third chapter of this thesis, namely an extension of the Brouwer fixed point theorem to functions on (L0)^d . We define a conditional simplex, which is a simplex with respect to L0 , and prove that every local, sequentially continuous function has a fixed point. We extend the fixed point theorem to arbitrary closed, L0-convex sets. A more general structure than L0 -modules is the concept of conditional sets. In the fourth chapter of the thesis, we study conditional topological vector spaces. We examine the concept of duality for conditional sets and prove results of functional analysis: among others, the Banach-Alaoglu and the Krein-Šmulian theorem. Any L0 -module being a conditional set allows to apply all results to L0 -theory. In the fifth chapter, we discuss the property of transitivity of relations and its connection to certain forms of representations. After a survey of common representations of preferences, we attend to relations induced by moving convex sets which are relations of the form that x is preferred to y if and only if x − y is in a convex set depending on y. We examine in which cases such a representation is transitive. Finally, we exhibit nontransitivity due to dissimilarity of the compared object and discuss representations for relations of that type.

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Minář, Petr. "Návrh a optimalizace prostoru hydrostatické kapsy." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229483.

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This diploma thesis deals with an optimization of hydrostatic slide of the large-portal gantry machine FRU (TOS Kuřim). First part of the thesis concerns with an analysis of the current practice in hydrostatic guides in the field of heavy gantry machines, an usage of alternative materials for a construction of carrying parts of machines, and possibilities of current simulation methods. Aim of the second part of this thesis is a brief clarification of the principle of mathematical optimization, and creation of general methodology of construction optimization by means of system analysis. Optimization calculations were processed by ANSYS Workbench 11.0. There is achieved adjusted and optimized design of the hydrostatic slide as the result of the thesis. Moreover, the comparison of key deformations was added. Created methodology is applicable in both an area of construction of gantry machines, and a wide spectrum of construction fields.

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Calisti, Valentin. "Synthèse de microstructures par optimisation topologique, et optimisation de forme d’un problème d’interaction fluide-structure." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0225.

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Élaboration d'une procédure d’optimisation topologique s’appuyant sur la dérivée topologique, dans le cadre d’un schéma d’homogénéisation d’ordre supérieur basé sur les développements asymptotiques. L’objectif est d’étendre les développements déjà réalisés en optimisation topologique dans le cadre de l’élasticité du premier gradient, au cas de l’élasticité non-classique sur la base du schéma d’homogénéisation menant à un milieu de gradient supérieur, et d’implémenter un algorithme d’optimisation approprié dans un code de calcul Development of a optimization procedure with the topological derivative, in the framework of a higher order homogenization scheme, based on asymptotic expansions. The objective is to extend the developments already realized in topological optimization as part of the elasticity of 'first gradient', to the case of non-classical elasticity on the basis of the homogenization scheme leading to a higher gradient medium, and to implement an appropriate optimization algorithm in a calculation code

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Ласько, Віктор Романович, та Viktor Lasko. "Розроблення проекту дільниці механічного цеху для виготовлення корпуса УГ 250.31.00.007 з дослідженням і топологічною оптимізацією адитивних технологій виготовлення деталей". Master's thesis, ТНТУ ім. І.Пулюя, ФМТ, м. Тернопіль, Україна, 2019. http://elartu.tntu.edu.ua/handle/lib/31258.

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В дипломній роботі виконано розроблення проекту дільниці механічного цеху для виготовлення корпуса УГ 250.31.00.007 з дослідженням і топологічною оптимізацією адитивних технологій виготовлення деталей. The thesis develops the design of machine shop project for the production of a body and explores the topological optimization of additive technology of parts manufacture. ВСТУП 1. АНАЛІТИЧНА ЧАСТИНА 1.1. Службове призначення та характеристики об'єкту виробництва. 1.2. Аналіз технічних вимог на виріб. 1.3. Аналіз технологічності конструкції деталі. 1.4. Аналіз базового технологічного процесу. 1.5. Висновки та постановка задачі на магістерську роботу. 2. НАУКОВО-ДОСЛІДНА ЧАСТИНА 2.1. Огляд методів топологічної оптимізації. 2.1.1. ESO-метод. 2.1.2. SIMP-метод. 2.1.3.Level-SET - метод. 2.2. Дослідження топологічної оптимізації корпусу УГ 250.31.00.007. 2.3. Порівняння топологічної оптимізації в різних програмних продуктах. 2.4. Сучасні тенденції у проектуванні деталей за допомогою топологічної оптимізації. 3. ТЕХНОЛОГІЧНА ЧАСТИНА 3.1. Характеристика типу та організаційної форми виробництва. 3.2. Вибір і технічне обгрунтування способу одержання заготовки. 3.3. Розрахунки припуску на поверхню деталі аналітичним способом. 3.4. Розроблення маршрутного технологічного процесу механічного оброблення корпусу УГ250.31.00.007. 3.5. Методи забезпечення технологічних вимог в процесі оброблення деталі. 3.6. Опис проектного маршрутного технологічного процесу за операціями. 3.7. Розроблення операційного технологічного процесу. 3.7.1. Розрахунки режимів різання і нормування вертикально-фрезерної операції 005. 3.7.2. Розрахунки режимів різання І нормування плоскошліфувальної операції 035. 3.8. Визначення похибки базування заготовки. 4. КОНСТРУКТОРСЬКА ЧАСТИНА 4.1. Проектування технологічного оснащення. 4.1.1. Вибір і обгрунтування принципу дії пристрою, структурної схеми. 4.1.2. Силовий розрахунок параметрів приводу. 4.1.3. Розрахунок пристрою на точність. 4.1.4. Опис конструкції та роботи пристрою. 4.2. Розрахунок спеціального різального інструменту. 4.3. Розрахунок на точність контрольного пристрою. 4.4. Розрахунок засобів автоматизації та механізації. 5. СПЕЦІАЛЬНА ЧАСТИНА 5.1. Огляд сучасного програмного забезпечення для топологічної оптимізації деталей. 5.2. Методи вирішення проблем «шахової дошки» в процесі топологічної оптимізації за допомогою САПР. 6. ПРОЕКТНА ЧАСТИНА 6.1. Визначення річної потреби в технологічному обладнанні. Складання зведеної відомості обладнання. 6.2. Вибір типу і розрахунок кількості вантажопідіймальних і транспортних засобів. 6.3. Розрахунки чисельності промислово-виробничого персоналу. 6.3.1 Розрахунки дійсного річного фонду часу. 6.3.2. Розрахунки чисельності виробничих робітників. 6.3.3. Розрахунки чисельності допоміжних робітників, інженерно-технічних працівників (ІТП) та МОП. 6.4. Розрахунки необхідної виробничої площі та побудова схеми планування дільниці. 6.5. Вибір типу приміщень, компоновка цеху, планування дільниці. 7. ОБГРУНТУВАННЯ ЕКОНОМІЧНОЇ ЕФЕКТИВНОСТІ 7.1. Визначення технологічної собівартості виготовлення корпусу 7.1.1. Техніко-економічне обгрунтування способу одержання заготовки 7.1.2. Визначення фонду заробітної плати виробничих робітників і величини їх середньомісячного заробітку. 7.1.3. Розрахунки накладних витрат. 7.1.3.1. Розрахунки загальновиробничих витрат. 7.1.3.2. Розрахунки адміністративних витрат. 7.1.3.3. Розрахунки витрат на збут. 7.1.4. Розрахунки повної собівартості та ціни деталі. 7.2. Визначення економічної ефективності проектного варіанту технологічного процесу виготовлення корпусу. 8. ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 8.1. Охорона праці при термічному, електрохімічному І електрофізичному обробленні металів. 8.2. Розрахунок повітряної завіси для проектованої дільниці механічного цеху. 8.3. Забезпечення безпечної експлуатації обладнання на проектованій дільниці. 8.4. Зменшення небезпеки виникнення пожеж на дільниці. 9. ЕКОЛОГІЯ 9.1. Вплив складових машинобудівного комплексу на довкілля. 9.1.1. Забруднення атмосфери. 9.1.2. Забруднення гідросфери. 9.2. Обгрунтування заходів з охорони навколишнього середовища, вибір устаткування для вловлювання пилу, туману, очищення стічних вод. 9.3. Оцінка екологічної ефективності на дільниці механічного цеху для виготовлення корпуса. ЗАГАЛЬНІ ВИСНОВКИ ДОДАТКИ ПЕРЕЛІК ПОСИЛАНЬ

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Hafidi, Alaoui Hamza. "Imagerie topologique ultrasonore des milieux périodiques." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0388/document.

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La détection, la localisation et le suivi de l’évolution de défauts dans les milieux périodiques et les guides d’ondes est un enjeu majeur dans le domaine du Contrôle Non Destructif (CND). La propagation d’ondes dans ce genre de milieux est complexe, par exemple lorsque la vitesse dépend de la fréquence (dispersion) ou de la direction de propagation (anisotropie). La signature du défaut peut également être « noyée » dans le champ acoustique renvoyé par la structure (réverbération ou diffusion multiple). C’est pour répondre à ces enjeux de taille que l’Optimisation Topologique (OT) a été adaptée aux problèmes de diffraction des ondes acoustiques par des défauts infinitésimaux afin d’obtenir des images de réflectivité des milieux inspectés. La méthode peut être appliquée à toutes sortes de milieux, quelle que soit leur complexité, à condition d’être capable de simuler correctement (sur un milieu de référence) la propagation des ondes de l’expérience physique. En s’inspirant de l’OT, les travaux de cette thèse proposent de mettre en oeuvre des méthodes d’imagerie qualitatives adaptées aux spécificités des Cristaux Phononiques (CP) et des guides d’ondes. Dans un premier temps, nous nous attachons à la description du formalisme mathématique de l’Optimisation Topologique et de la Full Waveform Inversion (FWI). Bien que ces méthodes ne cherchent pas à résoudre les mêmes problèmes inverses, nous mettons en évidence leurs points communs. Dans un deuxième temps, nous appliquons l’Imagerie Topologique (IT) à l’inspection en réflexion des milieux faiblement hétérogènes. Dans un troisième temps, nous nous inspirons de l’IT pour définir une nouvelle variante de celle-ci nommée Imagerie Topologique Hybride (ITH). Nous appliquons ces méthodes pour l’inspection en réflexion des CP crées par des tiges d’acier immergées dans l’eau. Nous comparons les performances de ces méthodes en fonction du type de défaut dans le CP. Les simulations numériques correspondantes à certains cas d’étude sont appuyées par des essais expérimentaux concluants. Dans un quatrième temps, nous adaptons l’IT à une configuration d’inspection en transmission afin de mette en oeuvre une méthode de Structural Health Monitoring (SHM) des guides d’ondes. A ce propos, nous avons mis au point une nouvelle méthode d’imagerie mieux adaptée que l’IT aux configurations d’inspection en transmission The detection, localization and monitoring of the evolution of defects in periodic media and waveguides is a major issue in the field of Non-Destructive Testing (NDT). Wave propagation in such media is complex, for example when the velocity depends on the frequency (dispersion) or direction of propagation (anisotropy). The signature of the defect can also be "embedded" in the acoustic field reflected by the structure (reverberation or multiple diffusion). It is to answer these stakes of the size that the Topological Optimization (TO) has been adapted to the problems of diffraction of the acoustic waves by infinitesimal defects in order to obtain reflectivity images of the inspected media. The method can be applied to all kinds of media, regardless of their complexity, provided an exact simulation of the wave propagation in a reference medium (without defects) is performed. Inspired by the TO, the work of this thesis proposes to implement qualitative imaging methods adapted to the specificities of Phononic Crystals (PC) and waveguides. First, we focus on the description of the mathematical formalism of Topological Optimization and Full-Waveform Inversion (FWI). Although these methods do not try to solve the same inverse problems, we highlight their similarities. In a second step, we apply Topological Imaging (TI) to the inspection in pulse-echo configuration of weakly heterogeneous media. Thirdly, we draw inspiration from TI to define a new variant of this method called Hybrid Topological Imaging (HTI).We apply these methods for the pulse-echo configuration inspection of PCs created by steel rods immersed in water.We compare the performance of these methods according to the kind of defects in the PC. Numerical simulations for some case studies are supported by conclusive experimental trials. In a fourth step, we adapt the TI to a pitch-catch configuration in order to implement a new method of Structural Health Monitoring (SHM) of waveguides. In this regard, we have developed a new imaging method that is better suited than TI to pitch-catch configurations

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Senne, Thadeu Alves 1985. "Otimização topologica de mecanismos flexiveis." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307121.

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Orientador: Francisco de Assis Magalhães Gomes Neto Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica Made available in DSpace on 2018-08-13T12:28:53Z (GMT). No. of bitstreams: 1 Senne_ThadeuAlves_M.pdf: 1074089 bytes, checksum: 76e0320b61aeb0cef5475189e51d218e (MD5) Previous issue date: 2009 Resumo: Neste trabalho, estudamos algumas formulações possíveis para o problema de otimização topológica de um mecanismo flexível, propostas por Nishiwaki et al. [33], Lima [26] e Sigmund [37]. Para resolver os problemas de programação não linear associados a cada uma das formulações estudadas, usamos uma versão globalmente convergente da Programação Linear Seqüencial, inspirada no trabalho de Gomes et al. [18], e uma versão globalmente convergente do Método das Assíntotas Móveis, desenvolvida por Svanberg [46]. Fazemos uma análise comparativa do desempenho desses dois métodos de otimização, no que diz respeito às topologias ótimas obtidas para as estruturas e ao esforço computacional para a resolução dos problemas de otimização topológica. Comparamos também a eficácia de alguns filtros espaciais propostos na literatura, que têm o papel de evitar o aparecimento de regiões semelhantes a um tabuleiro de xadrez nas topologias ótimas das estruturas Abstract: In this work, we study some possible formulations for the topology optimization problem of a compliant mechanism, proposed by Nishiwaki et al. [33], Lima [26] and Sigmund [37]. To solve the nonlinear programming problem associated to each formulation, we use a globally convergent version of the Sequential Linear Programming, inspired in the Gomes' et al. [18] work, and a globally convergent version of the Method of Moving Asymptotes, developed by Svanberg [46]. We make a comparative analysis of the performance of these two optimization methods, with respect to the optimum topologies obtained for the structures and to the computational e ort for the resolution of the topology optimization problems. Also, we compare the e ciency of some spatial lters already proposed in the literature, used to avoid the occurrency of regions similar to a checkerboard in the optimum topology of the structures Mestrado Matematica Aplicada - Otimização Mestre em Matemática Aplicada

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Rakotobe, Mickaël. "Modélisation d'écoulement de fluide en milieu poreux hétérogène et application en optimisation topologique." Electronic Thesis or Diss., La Réunion, 2022. http://www.theses.fr/2022LARE0023.

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Je m’intéresse dans cette thèse à la modélisation d’un écoulement de fluide en milieu poreux hétérogène avec une application en optimisation topologique. L’écoulement s’effectuant dans les zones avec et sans matière poreuse et l’optimisation topologique modifiant ces zones, une hétérogénéité spatiale est donc présente. Dans cette thèse, je propose un modèle d’écoulement qui fait apparaître les gradients de porosité pour tenir compte de cette hétérogénéité spatiale. Le modèle proposé s’obtient avec une technique de prise de moyenne volumique et se différencie de ceux de la littérature par les termes qui s’y trouvent. La reproduction de résultats expérimentaux et de simulations numériques de la littérature montre un bon fonctionnement de la méthode de résolution numérique mise en œuvre sur OpenFoam. Les cas d’applications utilisés sont ceux du bouchon poreux et du phénomène de channelling. Je choisis la porosité en tant que quantité physique dépendante de la variable d’optimisation. C’est la perméabilité qui est habituellement choisie dans la littérature, elle est calculée dans cette thèse par la valeur de la porosité avec une équation de Kozeny-Carman. La fonction objectif utilisée porte sur les pertes de charge. L’approche d’optimisation permet de reproduire les formes optimisées de la littérature et de pénaliser la vitesse de l’écoulement quand une matière poreuse proche d’un solide est utilisée. Je montre dans cette thèse l’impact de plusieurs paramètres sur le fonctionnement de l’algorithme d’optimisation : l’écriture du modèle d’écoulement, les termes avec un gradient de porosité, la perméabilité, la porosité et le diamètre moyen effectif des grains. Ainsi, les formes optimisées composées d’une répartition de matière poreuse sont influencées par ces différents paramètres In this thesis, I am interested in the modelling of a fluid flow in a heterogeneous porous medium with an application in topological optimization. As the flow takes place in areas with and without porous material and the topological optimization modify these areas, spatial heterogeneity is present. In this thesis, I propose a flow model that shows porosity gradients to account for this spatial heterogeneity. The proposed model is obtained using a volume averaging technique and differs from those in the literature in the terms it contains. The reproduction of experimental results and numerical simulations from the literature shows that the numerical solution method implemented in OpenFoam works well. The application cases used are the porous plug and the channelling phenomenon. I choose porosity as a physical quantity dependent on the optimization variable. It is the permeability that is usually chosen in the literature, it is calculated in this thesis by the porosity value with a Kozeny-Carman equation. The objective function used is the pressure drop. The optimization approach allows reproducing the optimized shapes from the literature and to penalize the flow velocity when a porous material close to a solid is used. I show in this thesis the impact of several parameters on the operation of the optimization algorithm: the writing of the flow model, the terms with a porosity gradient, the permeability, the porosity and the effective mean grain diameter. Thus, the optimized shapes composed of a distribution of porous material are influenced by these different parameters

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Laszczyk, Laurent. "Homogénéisation et optimisation topologique de panneaux architecturés." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00721807.

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La conception sur-mesure de matériaux architecturés à l'échelle du milli/centimètre est une stratégie pour développer des matériaux de structure plus performants vis-à-vis de cahiers des charges multifonctionels. Ce travail de thèse s'intéresse en particulier à la conception optimale de panneaux architecturés périodiques, dans le but de combiner des exigences mécaniques de flexion et de cisaillement, ainsi que de conductivité thermique. Le comportement élastique peut être prédit grâce à l'identification sur la cellule périodique des coefficients de la matrice des souplesses équivalente. Ces calculs d'homogénéisation ont été mis en oeuvre par éléments finis pour estimer en particulier les souplesses en flexion et en cisaillement transverse. Après validation expérimentale, cette méthode de calcul constitue un outil d'évaluation des performances mécaniques pour chaque géométrie de cellule périodique (2D ou 3D). À titre d'exemple, et dans un contexte de développement de solutions matériaux architecturés pour l'automobile, la conception de tôles "texturées" est proposée en menant une étude paramétrique à l'aide de cet outil. L'implémentation d'un algorithme d'optimisation topologique couplé à la procédure d'homogénéisation permet d'enrichir les méthodes de conception sur-mesure en élargissant l'espace de recherche des "architectures". Après l'étude modèle du compromis entre flexion et cisaillement, le cas industriel d'un panneau sandwich isolant est traité. Dans ce cas, l'optimisation fournit plusieurs compromis prometteurs entre rigidité en cisaillement et isolation thermique. Ces géométries ont été réalisées et testées, et une nouvelle version améliorée du panneau sandwich a été sélectionnée.

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Deneffle, Romain. "Définition d'une méthodologie d'allègement de structures sous contrainte de rigidité fonctionnelle, cas d'une machine-outil." Thesis, Université Clermont Auvergne‎ (2017-2020), 2017. http://www.theses.fr/2017CLFAC022.

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En réponse à des contraintes écologiques et économiques de plus en plus forte dans l’industrie, la problématique de réduction et de maîtrise de la consommation énergétique est aujourd’hui prise en considération dans le domaine de la machine-outil. Cette thèse s’inscrit dans le cadre du projet Green HSM porté par l’entreprise PCI-SCEMM ayant pour but de réduire la consommation énergétique d’une machine-outil de 30%. L’étude s’est focalisée sur le thème spécifique de l’allègement de structure. L’objectif est de concevoir des structures de machines-outils avec des masses mobiles les plus faibles possibles tout en gardant une rigidité fonctionnelle.Deux méthodes d’allègement de structures sont proposées dans le cadre de cette thèse. La première présente une méthode d’optimisation de structure de machines-outils par analyse de contraintes. Cette méthode a permis un allègement de deux pièces principales de la structure de 6,5% et 9% pour une réduction globale de la consommation énergétique de 3%.Une autre méthode pour concevoir une structure de machines-outils plus légère utilisant l’optimisation topologique est proposée. La méthode s’appuie sur deux paramètres spécifiques : l’espace de conception et DISCRETE. Cette méthode est présentée dans l’optimisation d’un cas simple de poutre encastrée soumise à un effort de flexion et donne de bons résultats. L’utilisation de la méthode sur le chariot X d’une machine-outil met en évidence les limitations de l’optimisation topologique dans le cas d’étude de structures complexes et l’influence du choix de la solution initiale In response to the increase of environmental and economic constraints in industry, the issue of reducing and controlling energy consumption is highlighted in machine tool context. This thesis is part of the Green HSM project carried out by the PCI-SCEMM company with the aim of reducing the energy consumption of a machine tool by 30%. The study focused on the specific topic of lightweight design. The objective is to design machine tool structures with the smallest mass while maintaining functional rigidity.Two methods of lightening structures are proposed in the framework of this thesis. The first one presents a method for optimizing the structure of machine tools by stress analysis. This method allows reducing the mass of two main parts of the structure of 6.5% and 9% for an overall reduction in energy consumption of 3%. Another method for designing a lighter machine structure using topological optimization is proposed. The method is based on two specific parameters: the space design and DISCRETE. This method is presented in the optimization of a simple case of embedded beam subjected to a bending effort and gives good results. The use of the method on the X-axis carriage of a machine tool highlights the limitations of topological optimization in the case of complex structure studies and the influence of the initial solution choice

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Vilamot, Raphaël. "Optimisation de la configuration magnétique d'un propulseur à effet Hall par résolution du problème magnétostatique inverse." Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/14668/1/vilamot.pdf.

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Les travaux effectués lors de cette thèse portent sur l'optimisation de la configuration magnétique des propulseurs à effet Hall. Ceci regroupe deux objectifs: d'une part la réalisation d'un propulseur à effet Hall dont la topologie magnétique est entièrement paramétrable, ce qui constituera un outil précieux pour l'étude de l'impact du champ magnétique sur le fonctionnement du propulseur et d'autre part, l'étude de moyen de conception rationalisée de circuits magnétiques pour ces mêmes propulseurs. Le premier sujet a conduit à la réalisation du PPS-Flex, un propulseur proposant une structure de circuit magnétique innovante offrant un grand nombre de degrés de liberté en termes de réglage du champ magnétique produit. La deuxième thématique a quant à elle été abordée en s'appuyant sur des méthodes d'optimisation (paramétrique et topologique) permettant d'aboutir à un circuit magnétique optimal pour un ou plusieurs critères de conception (fidélité du champ magnétique généré, minimisation de la masse, du volume total, etc.)

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Senne, Thadeu Alves 1985. "Otimização topologica de estruturas sob não linearidade geométrica." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307120.

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Orientador: Francisco de Assis Magalhães Gomes Neto Tese (doutorado )- Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica Made available in DSpace on 2018-08-22T00:37:54Z (GMT). No. of bitstreams: 1 Senne_ThadeuAlves_D.pdf: 4979548 bytes, checksum: 0317347b212e7649dd09e5d5388e618e (MD5) Previous issue date: 2013 Resumo: Nos últimos anos, a otimização topológica vem sendo amplamente adotada nas indústrias automotiva e aeroespacial, e no projeto de um tipo especial de estruturas, denominado mecanismo flexível. Grande parte dos trabalhos na área de otimização topológica considera que a estrutura possui uma relação linear entre deformações e deslocamentos, ou seja, supõe-se que os deslocamentos sofridos pela estrutura sejam pequenos. Todavia, para algumas estruturas, essa hipótese não é válida, sendo necessário supor que os deslocamentos são grandes, o que implica numa relação não linear entre deformações e deslocamentos. Nesse caso, dizemos que a estrutura está sob não linearidade geométrica. O objetivo desta tese de doutorado é a obtenção da topologia ótima de estruturas e de mecanismos flexíveis sob não linearidade geométrica através um novo algoritmo de otimização, denominado Programação Linear por Partes Sequencial (PLPS). Este método consiste na resolução de subproblemas de programação linear por partes convexas, onde são introduzidas informações sobre a diagonal da matriz Hessiana da função objetivo. Para acelerar o algoritmo, tais subproblemas são convertidos em problemas de programação linear. Provamos que a PLPS é globalmente convergente a pontos estacionários. Além disso, nossos experimentos numéricos realizados com estruturas e mecanismos flexíveis sujeitos a grandes deslocamentos mostram que a PLPS é eficiente e robusta Abstract: In the last years, topology optimization has been broadly applied in the automotive and aerospatial industries, and to a special kind of structure, named compliant mechanism. Most papers on topology optimization consider that the structure has a linear relation between strains and displacements, meaning that the displacements of the structure are small. However, for some structures this assumption is not valid, and it is necessary to suppose that the displacements are large, implying in a nonlinear relation between strains and displacements. In this case, we say that the structure is under geometrical nonlinearity. The objective of this doctoral thesis is to obtain the optimum topology of structures and compliant mechanisms under geometrical nonlinearity through a new optimization algorithm, named Sequential Piecewise Linear Programming (SPLP). This method consists in the solution of convex piecewise linear programming subproblems that contain information about the diagonal of the Hessian matrix of the objective function. To speed up the algorithm, these subproblems are converted into linear programming ones. We prove that the SPLP is globally convergent to stationary points. Besides, our numerical experiments with structures and compliant mechanisms under large displacements also show that the SPLP is efficient and robust Doutorado Matematica Aplicada - Otimização Doutor em Matemática Aplicada

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Caubet, Fabien. "Détection d’un objet immergé dans un fluide." Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3006/document.

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Cette thèse s’inscrit dans le domaine des mathématiques appelé optimisation de formes. Plus précisément, nous étudions ici un problème inverse de détection à l’aide du calcul de forme et de l’analyse asymptotique. L’objectif est de localiser un objet immergé dans un fluide visqueux, incompressible et stationnaire. Les questions principales qui ont motivé ce travail sont les suivantes :– peut-on détecter un objet immergé dans un fluide à partir d’une mesure effectuée à la surface ?– peut-on reconstruire numériquement cet objet, i.e. approcher sa position et sa forme, à partir de cette mesure ?– peut-on connaître le nombre d’objets présents dans le fluide en utilisant cette mesure ?Les résultats obtenus sont décrits dans les cinq chapitres de cette thèse :– le premier met en place un cadre mathématique pour démontrer l’existence des dérivées de forme d’ordre un et deux pour les problèmes de détection d’inclusions ;– le deuxième analyse le problème de détection à l’aide de l’optimisation géométrique de forme : un résultat d’identifiabilité est montré, le gradient de forme de plusieurs types de fonctionnelles de forme est caractérisé et l’instabilité de ce problème inverse est enfin démontrée ;– le chapitre 3 utilise nos résultats théoriques pour reconstruire numériquement des objets immergés dans un fluide à l’aide d’un algorithme de gradient de forme ;– le chapitre 4 analyse la localisation de petites inclusions dans un fluide à l’aide de l’optimisation topologique de forme : le gradient topologique d’une fonctionnelle de forme de Kohn-Vogelius est caractérisé ;– le dernier chapitre utilise cette dernière expression théorique pour déterminer numériquement le nombre et la localisation de petits obstacles immergés dans un fluide à l’aide d’un algorithme de gradient topologique This dissertation takes place in the mathematic field called shape optimization. More precisely, we focus on a detecting inverse problem using shape calculus and asymptotic analysis. The aim is to localize an object immersed in a viscous, incompressible and stationary fluid. This work was motivated by the following main questions:– can we localize an obstacle immersed in a fluid from a boundary measurement?– can we reconstruct numerically this object, i.e. be close to its localization and its shape, from this measure?– can we know how many objects are included in the fluid using this measure?The results are described in the five chapters of the thesis:– the first one gives a mathematical framework in order to prove the existence of the shape derivatives oforder one and two in the frame of the detection of inclusions;– the second one analyzes the detection problem using geometric shape optimization: an identifiabilityresult is proved, the shape gradient of several shape functionals is characterized and the instability of thisinverse problem is proved;– the chapter 3 uses our theoretical results in order to reconstruct numerically some objets immersed in a fluid using a shape gradient algorithm;– the fourth chapter analyzes the detection of small inclusions in a fluid using the topological shape optimization : the topological gradient of a Kohn-Vogelius shape functional is characterized;– the last chapter uses this theoretical expression in order to determine numerically the number and the location of some small obstacles immersed in a fluid using a topological gradient algorithm

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Beruashvili, Vasili. "Topologická optimalizace závěsu na poddajném podkladu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417913.

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Tato diplomová práce se zabývá modifikací původního tvaru součásti za účelem co nejlepšího splnění provozních podmínek daného zatížení a omezujících podmínek v programech M.S.C. NASTRAN, M.S.C. PATRAN a FUSION 360. Součást je připevněna na ortotropní desce (sendvičovém panelu). Cílem této práce je zjištění efektu elastického podkladu na výsledky optimalizace. Součást bude optimalizována za použití různých cílových funkcí a omezení. Elastický podklad změní tuhost, což může změnit napěťový stav součásti. Únosnost původního a modifikovaného tvaru bude srovnána pomocí programu M.S.C NASTRAN/PATRAN. Po tvarové optimalizaci má být 3D model připravený pro výrobní proces, který bude cenově nejefektivnější.

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Porto, Eduardo Castelo Branco. "Metodo da homogeneização aplicado a otimização estrutural topologica." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265173.

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Orientador: Renato Pavanello Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica Made available in DSpace on 2018-08-07T01:37:07Z (GMT). No. of bitstreams: 1 Porto_EduardoCasteloBranco_M.pdf: 1249639 bytes, checksum: ecf2198ecf41330cd50bfdb24c3bdb08 (MD5) Previous issue date: 2006 Resumo: Este trabalho tem por objetivos a investigação e a implementação de um método de otimização estrutural topológica baseado no uso de microestruturas. Dois modelos de microestrutura são introduzidos no problema de projeto ótimo: um ortotrópico com vazios, via homogeneização, e outro isotrópico com penalidade, via equação constitutiva artificial. As propriedades mecânicas efetivas de tais modelos são determinadas através de um programa iterativo implementado, baseado na abordagem da homogeneização. A análise estrutural é então realizada através do método dos elementos finitos e a topologia ótima é obtida com o uso de um otimizador baseado em critérios de otimalidade. São feitas investigações acerca dos parâmetros envolvidos na técnica de homogeneização, assim como são resolvidos problemas elastoestáticos e elastodinâmicos lineares de estado plano de tensão envolvendo critérios de projeto em rigidez e em freqüência natural e restrição de volume. Os algoritmos, implementados em ambiente Matlab, têm sua eficácia comprovada mediante a resolução de problemas clássicos existentes na literatura. E com a implementação dos modelos de material ortotrópico com vazios e isotrópico com penalidade é possível explorar as principais características e potencialidades de cada abordagem Abstract: This work aims to investigate and implement a structural topology optimization method based on microstructures. Two microstructure models are introduced in the optimal design problem: one orthotropic with holes, by homogenization, and other isotropic with penalization, by artificial constitutive equation. An implemented iterative program, based on the homogenization approach, determines the effective mechanical properties of each material model. Structural analyses are performed by using the finite element method and optimal topologies are obtained using an optimizer based on optimality criteria. Investigations concerning the parameters related to the homogenization technique are carried out. Linear elastic static and dynamic problems of structures in plane stress state are solved as well, concerning stiffness and natural frequency design criteria and with a constraint on volume. The solution of classic structural problems encountered in literature has demonstrated the effectiveness of the implemented Matlab codes and the implementation of the orthotropic and isotropic material models has made possible the investigation of the main characteristics and potentialities of each approach Mestrado Mecanica dos Sólidos e Projeto Mecanico Mestre em Engenharia Mecânica

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Zhao, Zhidong. "Optimisation d'antennes et de réseaux d'antennes planaires par gradient de forme et ensembles de niveaux (Level Sets)." Thesis, Nice, 2015. http://www.theses.fr/2015NICE4097.

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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

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Marcal, Roberto Capparelli. "UM MODELO PARA O PROBLEMA DA TOPOLOGIA E DO DIMENSIONAMENTO EM REDES DE AR COMPRIDO." Pontifícia Universidade Católica de Goiás, 2015. http://localhost:8080/tede/handle/tede/2461.

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Made available in DSpace on 2016-08-10T10:40:24Z (GMT). No. of bitstreams: 1 Roberto Capparelli Marcal.pdf: 1385634 bytes, checksum: 037e447d80e3c2c33c23560ac2c75dca (MD5) Previous issue date: 2015-03-05 This study aimed to construct a model for the simultaneous optimization of the topology and design of compressed air pipeline networks. The proposed model consists of two parts; the objective functions and a set of constraints. This model is a nonlinear mixed multiobjective programming. The function of this model is to optimize the diameters of the tubes and the topology of an air system under study, presenting a set of effective solutions while minimizing costs and pressure drop, given the constraints that enable each point of air consumption is treated in their minimum requirements of flow and pressure. For the verification of the proposed model behavior, data from a small network and obtained were applied efficient solutions for decision making. Este trabalho teve como objetivo a construção de um modelo para a otimização simultânea da topologia e do dimensionamento de redes de ar comprimido. O modelo proposto é composto de duas partes: as funções objetivos e um conjunto de restrições. Este modelo é um modelo de programação não linear misto multiobjetivo. A função deste modelo é otimizar os diâmetros e a topologia dos tubos de uma rede de ar em estudo, apresentando um conjunto de soluções eficientes minimizando os custos e a perda de carga e atendendo as restrições que possibilitem que cada ponto de consumo de ar comprimido seja atendido em seus requerimentos mínimos de vazão e pressão. Para a verificação do comportamento do modelo proposto, foram aplicados dados de uma rede de pequeno porte e obtidos as soluções eficientes para a tomada de decisão.

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Kecík, Samuel. "Topologická optimalizace pohyblivé, pevné a základní desky elektromechanického vstřikolisu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401534.

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The master thesis deals with the design of geometry of plates of the injection molding unit using the FEM tool Topological Optimization. The reason for this is to reduce the weight of these components, which is beneficial in the transport and assembly of the injection molding machine. However, the final models of geometry of plates must meet certain requirements in terms of the limit state of deformation, the limit state to the critical value of the equivalent stress. This condition involves both limit state of elasticity and limit state of fatigue. Computational modeling and also Topological Optimization are performed in ANSYS Workbench.

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Iwamura, Rafael Santos. "Minimax approach applied to topology optimization of structures subjected to multiple load cases." Instituto Tecnológico de Aeronáutica, 2013. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2834.

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This work investigates a topology optimization strategy for structures under multiple load cases. Typically compliance is calculated for each of the load cases in analysis and minimization is computed for a weighted average of the compliances, resulting in time consuming algorithms. A way to increase convergence speed is updating density on the element level. Instead of having an averaged compliance for the whole structure, it is proposed to compute it individually for every element. All load cases are analyzed, however only the ones of the maximum compliances are considered for sensitivity analysis. Thus compliance gradient is function of a few load cases at each element, reducing the processing time without significant weight penalty. The efficiency of the proposed technique is exemplified and compared to the one of a classical approach of multiple load case problem, solved using optimality criteria.

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Rakotondrainibe, Lalaina. "Optimisation topologique des liaisons dans les systèmes mécaniques." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX101.

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L'optimisation topologique est communément appliquée aux pièces mécaniques. En général, elle n'implique qu'une seule pièce dont les liaisons mécaniques sont supposées fixes. Cette thèse propose une autre approche de l'optimisation topologique où les liaisons sont des variables de conception, au même titre que la géométrie et la topologie de la forme de la pièce. On s'intéresse aux vis longues normalisées avec précontrainte de serrage. Le modèle de la vis est idéalisé, le but étant d'obtenir une représentation fonctionnelle, mais réaliste et peu coûteuse en termes de temps de calcul. Le modèle idéalisé est complété par des contraintes mécaniques spécifiques à la vis.Le problème consiste à optimiser simultanément la structure d'une pièce, d'une part, et les positions et le nombre de vis, d'autre part. La structure élastique est représentée par une fonction ligne de niveaux et elle est optimisée avec la méthode de variations de frontière d'Hadamard. Les positions sont optimisées avec un algorithme de descente de gradient paramétrique. Le concept de gradient topologique est adapté pour ajouter une petite vis idéalisée au meilleur emplacement avec une orientation optimale pour optimiser le nombre de vis. Cette optimisation couplée (structure et liaisons) est illustrée par des cas tests académiques 2d et 3d. Elle est ensuite appliquée à un cas test industriel simplifié. Le couplage fournit une pièce plus performante que l'optimisation de forme à liaisons fixées. Cette approche tend par conséquent à optimiser les systèmes assemblés Topology optimization is commonly used for mechanical parts. It usually involves a single part and connections to other parts are assumed to be fixed. This thesis proposes an other approach of topology optimization in which connections are design variables, as well as the structure. We focus on standard long bolt with prestressed state. This connection model is idealized to be enough representative but computationally cheap. The idealized model is complemented with mechanical constraints specific to the bolt.The problem is to optimize concurrently the topology and the geometry of a structure, on the one hand, and the locations and the number of bolts, on the other hand. The elastic structure is represented by a level-set function and is optimized with Hadamard's boundary variation method. The locations are optimized using a parametric gradient-based algorithm. The concept of topological derivative is adapted to add a small idealized bolt at the best location with the optimal orientation, and thus optimizes the number of bolts. This coupled topology optimization (shape and connections) is illustrated with 2d and 3d academic test cases. It is then applied on a simplified industrial test case. The coupling provides more satisfactory performance of a part than shape optimization with fixed connections. The approach presented in this work is therefore one step closer to the optimization of assembled systems

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Dissertations / Theses on the topic 'Topological optimization'

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