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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Análise de junta aparafusada de biela automotiva / Analysis of connecting rod bolted joint

Silva, Rafael Aguera Rezeno da [UNESP] 16 February 2016 (has links)
Submitted by RAFAEL AGUERA REZENO DA SILVA null (aguera.feg@gmail.com) on 2016-04-10T23:05:59Z No. of bitstreams: 1 Dissertação_Aguera.pdf: 5287076 bytes, checksum: 018a793b7d2956814528ec0cb549cc66 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-04-12T17:53:04Z (GMT) No. of bitstreams: 1 silva_rar_me_guara.pdf: 5287076 bytes, checksum: 018a793b7d2956814528ec0cb549cc66 (MD5) / Made available in DSpace on 2016-04-12T17:53:04Z (GMT). No. of bitstreams: 1 silva_rar_me_guara.pdf: 5287076 bytes, checksum: 018a793b7d2956814528ec0cb549cc66 (MD5) Previous issue date: 2016-02-16 / Em bielas automotivas, os parafusos atuam de maneira a manter a união entre capa e haste, suportando as cargas trativas, compressivas e transversais originadas no olhal maior. Para tais componentes, o dimensionamento de juntas aparafusadas torna-se complexo, visto que a disposição dos parafusos e a geometria do mancal conduzem ao surgimento de esforços excêntricos à face de fratura, elevando a criticidade do projeto. Em vista disso, e do reduzido número de publicações sobre o assunto, o presente trabalho propôs uma “abordagem híbrida” para a análise de juntas aparafusadas em bielas anguladas, utilizando resultados obtidos a partir de um modelo de elementos finitos simplificado e as ferramentas contidas no roteiro VDI 2230 parte 1. Além disso, foi avaliada a influência do fenômeno de abertura unilateral sobre a vida em fadiga dos fixadores utilizados em bielas anguladas, analisando os resultados obtidos de modo a desenvolver um critério de avaliação para a fadiga desses componentes. A despeito das restrições, a abordagem numérico-analítica desenvolvida demostrou-se atraente, tanto pelo baixo custo computacional associado, quanto por sua precisão, principalmente na determinação da força tensora residual mínima para a prevenção de abertura, mostrando-se adequado para processos de otimização multiparamétricos, selecionando designs promissores passíveis de posterior avaliação através de modelos refinados. Já as análises de influência do fenômeno abertura não apresentaram alterações sensíveis nos níveis de força adicional dos fixadores, fato esse relacionado com a posição dos pontos de abertura em relação ao parafuso e ao mancal. Apesar disso, as simulações realizadas demonstraram que as condições de carregamento avaliadas não influenciaram no diagrama de Haigh local dos nós críticos de cada fixador, o que sugere o uso de resultados extraídos de ensaios de fadiga como variáveis de entrada para simulações em juntas de bielas, incluindo assim as influências benéficas do processo de manufatura. / Connecting rods screws maintain the connection between cap and shank supporting the tensile, compressive and transversal loads applied on the big end. In this case, the design of bolted joints become complex since the screw’s position and bearing geometry lead to eccentric forces acting on the joint split line. Due to that and the reduced number of publications on the subject, this dissertation aims to develop a "hybrid approach" for the analysis of bolted joints in angled connecting rods, using results from a simplified finite element model as input for the VDI 2230 part 1 guideline. In addition to that, this study evaluates the influence of unilateral opening phenomenon on fasteners fatigue life, analyzing the results in order to develop a criterion for fatigue analysis of connecting rod bolts. Despite the restrictions, the “hybrid approach” proved to be attractive due to the low computational cost and accuracy, especially for the calculation of minimal residual tensile force to prevent opening, being suitable for multiparametric optimization during project early phases. The opening phenomenon showed no significant changes in fastener’s additional forces, fact related to the position of joint opening points. Nevertheless, the simulations showed that the loading conditions did not influence on the local Haigh diagram of critical nodes, which suggests the use of fasters fatigue tests as input variables for fatigue simulations, thus including the beneficial influences of the manufacturing process.
32

A residência habitual como elemento de conexão do mundo globalizado : sua incidência no direito internacional privado brasileiro

Jorge, Mariana Sebalhos January 2017 (has links)
Com a globalização e o constante aumento do fluxo internacional, tanto de mercadorias como de pessoas, observou-se o incremento dos negócios jurídicos com conexão internacional. A escolha da lei aplicável aos estatutos pessoais dividiu-se doutrinariamente entre defensores do elemento de conexão nacionalidade, como Mancini, e defensores do elemento de conexão domicílio, como Savigny. Cada vez mais conflitos envolvendo negócios jurídicos multijurisdicionais se tornaram uma realidade submetida aos tribunais internos dos países, de modo que a residência habitual surge como uma solução à dicotomia existente entre nacionalidade e domicílio. Nesse contexto, a finalidade da presente dissertação é analisar a incidência do elemento de conexão residência habitual no mundo globalizado e a incidência da residência habitual no direito internacional privado brasileiro. Para desenvolver os objetivos propostos, o estudo divide-se em dois capítulos. No primeiro capítulo é abordado o debate doutrinário existente na definição de residência habitual enquanto elemento de conexão, bem como a relação que possui com o domicílio – diferenciando-se domicílio em países de common law e de civil law. Neste primeiro momento ocorre também a análise do surgimento da residência habitual como elemento de conexão a determinar a lei aplicável, as suas primeiras utilizações pelas Convenções da Haia, previsões em legislações internas de diferentes países e também em âmbito unional através da União Europeia. O segundo capítulo destina-se à incidência da residência habitual no direito internacional privado brasileiro com a sua previsão em convenções já ratificadas pelo Brasil, bem como ao reconhecimento deste elemento de conexão no cenário brasileiro. Compreende, ainda, o estudo de julgados brasileiros que já utilizaram o critério da residência habitual e o futuro deste elemento de conexão no direito internacional privado brasileiro. Destacam-se as tentativas de atualização da Lei de Introdução às Normas do Direito Brasileiro que já previram a inserção do elemento de conexão residência habitual de forma subsidiária ao domicílio. Em conclusão, tem-se que a atualização legislativa do direito internacional privado brasileiro deve inserir o elemento de conexão residência habitual, em ascensão no mundo atualmente, com primazia, e não de modo subsidiário como os projetos anteriores. A primazia do critério residência habitual permite a aplicação da lei mais próxima à vida da pessoa ou à relação jurídica multiconectada, e ainda harmoniza o direito internacional privado, permitindo que o domicílio e a nacionalidade sejam utilizados de modo subsidiário. / With globalization and the constant increase of the international flow of both goods and people, it was observed the increase of the legal transactions with an international connection. The choice of law applicable to personal statutes was divided doctrinally between defenders of the connecting factor of nationality as Mancini and defenders of the connecting factor of domicile as Savigny. More and more conflicts involving multijurisdictional legal business have become a constant reality submitted to the domestic courts of the countries, so that habitual residence emerges as a solution to the dichotomy existing between nationality and domicile. In this context, the purpose of this dissertation is to analyze the incidence of the connection factor of habitual residence in the globalized world and the incidence of habitual residence in Brazilian private international law. In order to develop the proposed objectives, the study is divided into two chapters. The first chapter addresses the doctrinal debate existing in the definition of habitual residence as connecting factor, as well as the relation that has with the domicile - differentiating domicile in countries of common law of civil law. In this first moment there is also the analysis of the emergence of habitual residence as an connecting factor to determine the applicable law, its first uses by the Hague Conventions, provisions in internal legislation of different countries and also in a unional scope through the European Union. The second chapter focuses on the incidence of habitual residence in Brazilian private international law with its prediction in conventions already ratified by Brazil, as well as the recognition of this connecting factor in the Brazilian scenario. It also includes the study of Brazilian judges who have already used the criterion of habitual residence and the future of this connecting factor in Brazilian private international law. It analyzes the attempts to update the Brazilian private international law that have already predicted the insertion of the connecting factor of habitual residence in a subsidiary form to the domicile. In conclusion, it is noticed that the legislative update of Brazilian private international law must insert the connecting factor of habitual residence, rising in the world today, with primacy, and not in a subsidiary way as the previous projects. The primacy of habitual residence allows the application of the law closest to the person's life or to the multi-connected legal relationship, and also harmonizes private international law, allowing domicile and nationality to be used in a subsidiary manner.
33

Estrutura mista madeira-chapa dobrada submetida à flexão simples / Mixing structure timber-cold formed steel plates submitted to the bending

MONTEIRO, Vilma França 28 September 2007 (has links)
Made available in DSpace on 2014-07-29T15:03:30Z (GMT). No. of bitstreams: 1 Dissertacao Vilma Franca Monteiro.pdf: 2260410 bytes, checksum: f8bcbca2598f2aaf7b700c53a7bae20c (MD5) Previous issue date: 2007-09-28 / This work deals with theoretical and experimental study of timber beams and timber/cold formed steel plates composed beams, submitted to the bending. A combination of different materials aims to the exploitation the advantages of each material, of manner to have a viable set, in constructive terms, structural and economic. For the accomplish of the research, three beams wooden with dimensions 40mm x 120mm x 1050mm, six hardened beams wooden in the superior face with metallic profile in the dimensions 50mm x 25mm x 2mm and six beams of wooden stiffeners in faces inferior and superior with the same profile metallic had been assayed. The spacing between the connectors had been of 100mm, 200mm and 300mm. With the objective to supply given necessary the sizing, a theoretical formularization for the determination of the internal moment and for the estimative of the deflection was presented. For this, the mechanical properties of the wood, the steel and the connectors had been determined. With the results of the assays of characterization of the materials, the simple and mixing beams had been assayed to the bending, for reading of the deformations and maximum vertical displacements of the landslide in the extremities inferior and superior. Such values had been gotten by means of electric strain gauges and comparing clocks. They had been determined still: the tensions in the elements of the beams and the curves load versus displacement. It was observed that, in relation to the wooden simple beam, it had average increase at the ultimate load, for the beams with parts hardened in the compressed face, of 20%, and of 49 when placed stiffeners in the faces compressed and tensioned. In the value of the deflections it had average reduction of 15% when used stiffener in the superior face and of 49% in the parts with stiffeners in the faces was used compressed and tension. The biggest reduction in the deflections happened in the parts with lesser spacing between connectors, indicating that the influence of the interaction is bigger in relation to the displacements that in relation to the bending moment. In stress distribution diagram in the transversal sections it was adopted, in all the cases, the triangular form for the wood and for the profile it was adopted a rectangular form. It was obtained results that differ from the experimental values in 17% for the simple beams, in 16% for the parts hardened with profile in superior face and 21% for the parts hardened with profile in the faces upper/lower indicating that the formularization proposal can be applied with safety. In the calculation of the deflections the geometric properties of the mixing section, in elastic regimen, had been gotten with the homogenized section. An equation for the determination ofthe factor of correction of the estimated deflection, for the studied cases is presented. / Este trabalho trata de estudo teórico e experimental de vigas de madeira e vigas mistas, compostas de madeira e chapa dobrada, submetidas à flexão simples. A combinação de materiais diferentes visa ao aproveitamento das vantagens de cada material, de forma a se ter um conjunto viável, em termos construtivos, estruturais e econômicos. Para a efetivação da pesquisa, foram ensaiadas três vigas de madeira com dimensões aproximadas de 40mm x 120mm x 1050mm, seis vigas de madeira enrijecidas na face superior com perfil de chapa dobrada em U, nas dimensões 50mm x 25mm x 2mm e seis vigas de madeira enrijecidas nas faces inferior e superior, com o mesmo perfil metálico. Os espaçamentos entre os conectores foram de 100mm, 200mm e 300mm. Com o objetivo de fornecer dados necessários para o dimensionamento, foi apresentada uma formulação teórica para a determinação do momento interno e para a estimativa das flechas. Para tanto, foram determinadas as propriedades mecânicas da madeira, do aço e dos conectores. De posse dos resultados dos ensaios de caracterização dos materiais, foram ensaiadas à flexão as vigas simples e mistas, para leitura das deformações e deslocamentos verticais máximos e do deslizamento nas extremidades inferior e superior. Tais valores foram obtidos por meio de extensômetros elétricos e relógios comparadores. Determinaram-se ainda as tensões nos elementos das vigas e as curvas força x deslocamento. Observou-se que, em relação à viga simples de madeira, houve aumento médio no valor da força de ruptura, para as peças enrijecidas na parte comprimida, de 20%, e de 49% quando colocados enrijecedores nas faces comprimida e tracionada. No valor das flechas houve redução média de 15% quando se utilizou enrijecedor na face superior e de 49% nas peças com enrijecedores nas faces comprimida e tracionada. A maior redução nas flechas aconteceu nas peças com espaçamento menor entre onectores, indicando que a influência da interação é maior em relação aos deslocamentos do que em relação ao momento fletor. No diagrama de distribuição das tensões nas seções transversais adotou-se, em todos os casos, a forma triangular para a madeira e retangular para o perfil e chegou-se a resultados que diferem dos valores experimentais em 17% para as vigas simples, 16% para as peças enrijecidas com perfil na face superior e 21% para as peças enrijecidas com perfil nas faces superior e inferior indicando que a formulação proposta pode ser aplicada com segurança. No cálculo das flechas, as propriedades geométricas da seção mista, em regime elástico, foram obtidas com a seção homogeneizada. Apresenta-se uma equação para a determinação do fator de correção da flecha estimada, para os casos onde houve enrijecimento.
34

Undergraduate Students’ Connections Between the Embodied, Symbolic, and Formal Mathematical Worlds of Limits and Derivatives: A Qualitative Study Using Tall’s Three Worlds of Mathematics

Smart, Angela January 2013 (has links)
Calculus at the university level is taken by thousands of undergraduate students each year. However, a significant number of students struggle with the subject, resulting in poor problem solving, low achievement, and high failure rates in the calculus courses overall (e.g., Kaput, 1994; Szydlik, 2000; Tall, 1985; Tall & Ramos, 2004; White & Mitchelmore, 1996). This is cause for concern as the lack of success in university calculus creates further barriers for students who require the course for their programs of study. This study examines this issue from the perspective of Tall’s Three Worlds of Mathematics (Tall, 2004a, 2004b, 2008), a theory of mathematics and mathematical cognitive development. A fundamental argument of Tall’s theory suggests that connecting between the different mathematical worlds, named the Embodied-Conceptual, Symbolic-Proceptual, and Formal-Axiomatic worlds, is essential for full cognitive development and understanding of mathematical concepts. Working from this perspective, this research examined, through the use of calculus task questions and semi-structured interviews, how fifteen undergraduate calculus students made connections between the different mathematical worlds for the calculus topics of limits and derivatives. The analysis of the findings suggests that how the students make connections can be described by eight different Response Categories. The study also found that how the participants made connections between mathematical worlds might be influenced by the type of questions that are asked and their experience in calculus courses. I infer that these Response Categories have significance for this study and offer potential for further study and educational practice. I conclude by identifying areas of further research in regards to calculus achievement, the Response Categories, and other findings such as a more detailed study of the influence of experience.
35

Investigation of Design, Manufacture, Analysis, and Test of a Composite Connecting Rod Under Compression

Rohrbach, Thomas Juhl 01 March 2019 (has links)
Composite materials hold great potential for the replacement of traditional materials in machines utilized on a daily basis. One such example is within an engine block assembly where massive components inherently reduce the efficiency of the system they constitute. By replacing metal elements such as connecting rods, cylinder caps, or a crank shaft with composite alternatives, a significant increase in performance may be achieved with respect to mechanical strength, thermal stability, and durability, while also reducing mass. Exploration of this technology applied to a connecting rod geometry was investigated through a combination of process development, manufacturing, numerical analysis and testing. Process development explored composite material options based on experimental characterization, fabrication, and machining methods. Finite element analysis provided insight into model and data accuracy, as well as a basis for study on a unidirectional composite I-beam geometry. Destructive testing of the composite connecting rods provided data for a strength to weight ratio comparison with the original steel component. The composite connecting rods exhibited weight savings of 15%-17% that of the steel component. The rod made of woven composite material exhibited an elastic modulus of 68.1 Msi in its linear behavior before failure, thereby exhibiting a higher stiffness than the steel rod tested. Although the failure strengths were 25% below the required design load, the calculated strength to weight ratios showed favor for the composite alternatives.
36

Racionalizace výroby součásti zemědělského stroje / On the production of an agricultural machinery part and its optimization

Tenora, Tomáš January 2017 (has links)
This master's thesis deals with the process of machining a forged connecting rod in cooperation with the company Zetor Tractors a.s. The first chapter of the thesis is focused on a detailed introduction of the company. The second chapter includes an elaborate analysis of the technical documentation and requirements concerning the making process of the subject of study, specifically the construction of the connecting rod. In the third chapter, the current production technology is discussed and described in detail. The aim of the fourth chapter is to propose an innovative technology which can be used for the production of connecting rods in the required quality. The fifth chapter is aimed at testing the newly designed technology. In the final, sixth, chapter, a technical and economical evaluation of the proposed procedure is performed.
37

Zážehový tříválcový hvězdicový letecký motor / Petrol three-cylinder radial aircraft engine

Břečka, Marek January 2019 (has links)
The purpose of this thesis is to design a powertrain of petrol three-cylinder radial aircraft engine with the main parameters specified (bore, stroke, etc.), balancing inertia forces, stress analysis and determining of fatigue of the selected parts.
38

Aplikace síťového připojení měřicích přístrojů v technické diagnostice / Network connection application of measurement instruments in technical diagnostics

Gőtz, Lukáš January 2011 (has links)
This labor discusses with the possibilities of using a network connection devices in measurement technology from Agilent. It deals with the theoretical description of the different ways of measuring devices connected to computer networks and their use in laboratory teaching. Practical work is focused on creating automated utilities for selected tasks in the laboratory diagnosis of electrical materials in the software Agilent VEE Pro. The work is a detailed description of the labs in terms of setting and controlling the basic parameters created by the application. Installation and configuration of software and hardware communication tools are summarized in the brochure "How to handle a remote connection of measuring instruments over the Internet."
39

Ojnice plynového vidlicového šestnáctiválce / Connecting rod of gas V-sixteen engine

Laštovica, Karel January 2011 (has links)
This diploma thesis deals with a design of a stationary engine connecting rod, its stress analysis and its safety factors. The thesis is divided into several parts. At the beginning there is a short research of connecting rods construction and a description of the engine. Then the main dimensions of a piston group and a connecting rod are defined and its 3D model is created. Next, the calculations of forces acting on the connecting rod in the crankshaft mechanism, are carried out. The following part deals with a stress analysis of the model created by MPK. From the obtained stress results, the safety factor at fatigue limit in chosen places of the connecting rod is calculated. In the conclusion, the results of the stress analysis and set safety factor level, are recapitulated.
40

Hnací ústrojí tříválcového zážehového hvězdicového motoru / Powertrain of three-cylinder gasoline radial engine

Košař, Miroslav January 2013 (has links)
The purpose of this thesis is the design of a radial spark-ignition engine in two layout variations, the stress analysis of selected components using the finite element method, the eventual optimization of selected components and the determination of safety on their most strained locations.

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