A madeira de reflorestamento, em sua forma natural e roliça, apresenta-se como material eficiente para uso em edificações devido a suas propriedades físico-mecânicas e versatilidade funcional. Entretanto, a geometria cilíndrica e secções desiguais dificultam ligações entre os elementos roliços, exigindo cortes angulados e falquejamento das peças. Arranjos ou combinações entre peças envolvem tipos específicos de articulação ou conexão, vinculando o tipo de união à posição que as peças assumem no espaço tridimensional. Dado não existir conhecimento estruturado que permita antecipar as ligações apropriadas para cada arranjo ou combinação de peças, sugere-se a possibilidade de vincular a escolha de conexões com a composição arquitetônica, através de conexões genéricas. Este trabalho utilizou o paradigma da gramática de formas para, através de regras de geração, criar alternativas compositivas a partir de dois princípios conectivos: extremidade com extremidade e; extremidade com meio de peça. A vinculação entre os princípios de articulação e tipos de junções permitiu a formulação de modelos genéricos de peças de articulação, que minimizam a necessidade de cortes angulados nas peças roliças. Essas conexões genéricas podem adaptar-se à angulação do roliço permitindo que o mesmo seja cortado sem perda de material. / Reforestation wood, in its natural and round shape, emerges as an effective material for use in buildings, due to its physical and mechanical features and functional versatility. However, its cylindrical geometry and unequal sections difficult connections between the round elements, demanding angle cuts and rough-hewing of the pieces. Arrangements or combinations among pieces involve specific types of joints or connections, relating the type of union to the position that the pieces have in the threedimensional space. Since there is no structured knowledge that allows anticipating the appropriate connections for each arrangement or combination of pieces, the possibility of linking the choice of connections to the architectural composition, through generic connections, is suggested. This paper uses the shape grammars paradigm in order to create compositional alternatives to the types of joints, through generation rules. These data provide parameters to define two connective principles: top to top, and top to middle of the piece (cross section). From these principles, it is possible to model alternatives of articulations and to compare different options. The link between the principles of articulation and types of joints enabled the formulation of models of linkage pieces, which minimize the need for angle cuts in the round pieces. These generic connections can adapt to the angle of the round log, allowing it to be cut without loss of material.

A simulação numérica através do Método dos Elementos Finitos vem sendo utilizada em grande escala nos dias de hoje. Sendo que os trabalhos experimentais não conseguem cobrir toda a gama de situações que podem ocorrer em estruturas de concreto armado, o Método dos Elementos Finitos se apresenta como uma ferramenta para ampliar e generalizar os resultados obtidos através de modelos experimentais testados em laboratório. Estruturas de nós de pórti-co em concreto armado são largamente utilizadas em construções civis e possuem um com-portamento muito particular. Este trabalho tem por objetivo desenvolver um modelo numérico que simule as ligações viga-pilar nos nós de pórtico em concreto armado, examinando o com-portamento destes nós com diferentes configurações geométricas. O modelo computacional desenvolvido é avaliado, primeiramente, através de resultados experimentais bem conhecidos para vigas biapoiadas, para, em seguida, apresentarem-se as análises de nós de pórtico. Os resultados numéricos, utilizando-se dois modelos de malha: uma com elementos quadrangula-res quadráticos de oito nós e outra com elementos triangulares lineares de três nós, são com-parados com resultados experimentais disponíveis na literatura. Nesta comparação, pode-se verificar que a modelagem com malha de elementos triangulares lineares pode ser utilizada para análise de estruturas diversas. Podendo-se, também, utilizar esta malha como uma ferra-menta para elaboração de códigos computacionais restritos a elementos finitos com funções de interpolação lineares. Os resultados numéricos avaliam, também, a rotação relativa na liga-ção entre a viga e o pilar. / Numerical simulations by the Finite Element Method are being extensively used nowadays. Since experimental tests cannot cover the innumerous situations that can occur in reinforced concrete structures, the Finite Element Method presents itself as a tool to amplify and general-ize the results obtained throughout experimental models tested in the lab. Structures of rein-forced concrete frame joints are largely used in civil construction and have a very particular behavior. This work has the objective of developing a numerical model that simulates beam-column joints in reinforced concrete frames, examining their behavior with different geome-trical configurations. The developed computational model is firstly evaluated through well-known experimental results for simply supported beams to, in a second occasion, present the analyses of frame joints. The numerical results, with the consideration of two mesh models: one with quadratic quadrilateral elements of eight nodes and another with linear triangular elements of three nodes, are compared with experimental results from the literature. In this comparison, it is possible to verify that the modeling with linear triangular element meshes can be used for a diversity of structures. One can also use this mesh as a tool in the develop-ment of computational codes restricted to linear finite elements. The numerical results also evaluate the relative rotation at the joints between beams and columns.

Adhesive bonding of graphite epoxy composite laminates to itself or traditional metal alloys in modern aerospace and aircraft structural applications offers an excellent opportunity to use the most efficient and intelligent combination of materials available thus providing an attractive package for efficient structural designs. However, one of the major issues of adhesive bonding is the occasional formation of interfacial defects such as kissing or weak bonds in the bondline interface. Also, there are shortcomings of existing non-destructive evaluation (NDE) methods to non-destructively detect/characterize these interfacial defects and reliably predicting the bond shear strength. As a result, adhesive bonding technology is still not solely implemented in primary structures of an aircraft. Therefore, there is a greater demand for a novel NDE tool that can meet the existing aerospace requirement for adhesive bondline characterization. This research implemented a novel Acoustography ultrasonic imaging and digital image correlation (DIC) technique to detect and characterize interfacial defects in the bondline and determine bond shear strength in adhesively bonded composite-metal joints. Adhesively bonded Carbon Fiber Reinforced Plastic (CFRP) laminate and 2024-T3 Aluminum single lap shear panels subjected to various implanted kissing/weak bond defects were the primary focus of this study. Kissing/weak bonds were prepared by controlled surface contamination in the composite bonding surface and also by improperly mixing the adhesive constituent. SEM analyses were also conducted to understand the surface morphology of substrates and their interaction with the contaminants. Morphological changes were observed in the microscopic scale and the chemical analysis confirmed the stability of the contaminant at or very close to the interface. In addition, it was also demonstrated that contaminants migrated during the curing of the adhesive from CFRP substrate which caused a decrease of bond shear strength in single lap shear test samples. Through-transmission ultrasonics (TTU) Acoustography at 3.8 MHz showed promising results on the detectability of bondline defects in adhesively bonded CFRP-Al lap shear test samples. A correlation between Acoustography ultrasonic attenuation and average bond shear strength in CFRP-Al lap shear panels demonstrated that differential attenuation increased with the reduction of the bond shear strength. Similarly, optical DIC tests were conducted to identify and quantify kissing bond defects in CFRP-Al single lap shear joints. DIC results demonstrated changes in the normal strain (εyy) contour map of the contaminated specimens at relatively lower load levels (15% ~ 30% of failure loads). Kissing bond regions were characterized by negative strains, and these were attributed to high compressive bending strains and the localized disbonding taking placed at the bondline interface as a result of the load application. It was also observed that contaminated samples suffered from more compressive strains (εyy) compared to the baseline sample along the loading direction and they suffered from less compressive strains (εxx) compared to the baseline sample perpendicular to the loading direction. This demonstrated the adverse effect of the kissing bond on the adhesive joint integrity. This was a very significant finding for the reason that hybrid ultrasonic DIC is being developed as a faster, more efficient, and more reliable NDE technique for determining bond quality and predicting bond shear strength in adhesively bonded structures.

Devido à crescente utilização de componentes eletrônicos nos veículos automotores, as exigências mecânicas nesses itens estão cada vez maiores. Nos primeiros veículos a eletrônica embarcada era inexistente, em meados do século passado, passou a ser pequena e utilizada somente para funções de funcionamento e pouco importantes para a segurança, e caso ocorresse alguma falha não havia risco de vida. Nos automóveis desenvolvidos nas últimas décadas, os componentes eletrônicos estão sendo utilizados em aplicações como controle de injeção de combustível, sistemas de tração e freios, direções elétricas e acionamento de air bags, que estão diretamente relacionadas à segurança. Os requisitos de qualidade desses itens elevaram-se consideravelmente exigindo operação em temperaturas extremas e grandes acelerações. O processo de união mais eficiente para satisfazer aos requisitos mecânicos ainda é o de soldagem, mas há dificuldade em realizar as uniões sem danificar o componente ou prejudicar as propriedades elétricas em peças finas, da ordem de décimos de milímetros na espessura, com diferentes camadas de revestimento. Este trabalho analisa o processo de soldagem em capacitores, utilizando uma fonte de soldagem por resistência do tipo inversora, estudando os parâmetros de operação necessários para realizar a união de uma chapa de aço com 0,6 mm de espessura recoberta com três camadas de diferentes materiais: cobre, níquel e superfície externa de ouro. Este componente deve ser soldado a uma peça de alumínio. A influência da corrente de soldagem, pressão dos eletrodos, tempo de aplicação da corrente e tempo de retenção sobre a qualidade da união, avaliada pela resistência à tração alcançada e capacidade de realizar a união sem dano aos componentes ou ocorrência de falhas na superfície, foi analisada utilizando projeto de experimentos (DOE). Os resultados experimentais comprovam a eficiência do processo para utilização neste tipo de componentes garantindo a qualidade da junta e do componente para o desempenho de sua função. / Due to the increasing use of electronics in vehicles, the mechanical demands on these items are increasing. In the first vehicles onboard electronics was nonexistent in the middle of the last century, came to be used only for small, operating functions and unimportant to safety, and when there was a failure there was life threatening. In cars developed in recent decades, the electronic components are being used in applications such as fuel injection control, drive systems and brakes, directions and drive electric air bags, which are directly related to safety. The quality requirements of these items rose considerably demanding operation at extreme temperatures and high accelerations. The joining process more efficient to meet the mechanical requirements is still welding, but there is difficulty in performing the joints without damaging the component or interfere with the electrical properties of thin pieces, exhibiting tenths of a millimeter in thickness of different coating layers. This study examines the welding process in capacitors, using a inverter resistance welding power source, studying the operation parameters required to perform the joining of a steel plate 0.6 mm thick coated with three layers of different materials: a copper layer, a nickel layer and an external gold layer. This component must be welded to an aluminum plate. The influence of welding current, electrode pressure, time of current application and retention time on the quality of the union, as assessed by tensile resistance and ability to perform achieved union without damage to components or occurrence of any failures, was analyzed using design of experiments (DOE). The experimental results demonstrate the efficiency of the welding process in such components assuring the quality to perform its function.

Made available in DSpace on 2014-06-11T19:35:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-31Bitstream added on 2014-06-13T20:46:17Z : No. of bitstreams: 1 michelin_e_dr_botfm.pdf: 503394 bytes, checksum: 413a52db063af4196e2ab3748e2aa1a6 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A busca pela estratégia mais eficaz capaz de prevenir, modificar e controlar fatores de risco e doenças crônicas por meio de mudança no estilo de vida (MEV) tornou-se um grande desafio, além de conseguir a adesão, em longo prazo, e principalmente sem supervisão, aos bons hábitos adquiridos durante a intervenção com MEV. Diante disso, o objetivo do presente estudo foi avaliar o efeito da participação e do desligamento do programa de mudança do estilo de vida sobre nível de atividade e aptidão física, percepção de saúde e presença de Síndrome Metabólica em adultos da comunidade de Botucatu-SP. Estudo do tipo transversal com base na comunidade contou com 153 indivíduos previamente participantes de programa de MEV e alocados em grupos Controle, Adesão e Não-Adesão. As avaliações incluíram medidas antropométricas (peso corporal e estatura para cálculo do índice de massa corporal (IMC), circunferência abdominal, percentual de gordura, massa muscular e índice de massa muscular (IMM)), aptidão física (flexibilidade de tronco (sentar e alcançar) e força de preensão manual (dinamometria)) e nível de atividade física e estado de saúde (IPAQ longo, versão 8). Amostra sanguínea de jejum foi utilizada para análise bioquímica (glicemia, HDL-C e triglicerídios), aferição da pressão arterial (técnica auscultatória) e o diagnóstico da Síndrome Metabólica (SM) seguiu as recomendações do NCEP-ATPIII (2001) com adaptação da glicemia (≥ 100 mg/dL) em três momentos (pré-participação (M0), após intervenção de seis meses (M1) e após desligamento (M2) do programa de MEV). Análise de variância e modelo linear generalizado em medidas repetidas para comparação entre momentos e grupos, qui-quadrado, teste de proporção e modelo de regressão logística com nível de significância de 5%. O programa de MEV... / The search for more effective strategy able to prevent, control and modify risk factors and chronic diseases through lifestyle change (LSC) has become a major challenge, beyond to achieving the adherence in long term, especially without supervision, the good habits acquired during the LSC intervention. Thus, the purpose of this study was to evaluate the participation and disconnexion effects of lifestyle change program on physical activity level and fitness, on self-perceived health and metabolic syndrome presence in adults from Botucatu-SP’s community. Cross-sectional study of community-based had 153 subjects previously LSC program participants and allocated in Control, Adherence and Non-Adherence. The assessments included anthropometric measurements (weight and height to calculate body mass index (BMI), waist circumference, fat percentage, muscle mass and muscular mass index (MMI)), fitness (trunk flexibility (sit and reach) and handgrip strength (dynamometry)) and physical activity level and health status (IPAQ long version 8). Fasting blood sample was used for biochemical analysis (glucose, HDL-C and triglycerides), blood pressure measurement (auscultatory technique) and metabolic syndrome (MetS) diagnosis followed the NCEP-ATPIII (2001) recommendations with glucose adaptation (≥ 100 mg / dL) in three moments (pre-participation (M0), six months after intervention (M1) and after LSC program disconnexion (M2)). Variance analysis and generalized linear model for repeated measures to compare moments and groups, chi-square and proportions test and logistic regression model with 5% significance level. The LSC program significantly reduced work and housework physical activity, poor health perception and low physical activity level and increased leisure physical activity and flexibility, beyond to attenuate... (Complete abstract click electronic access below)

abstract: The present investigation is part of a long-term effort focused on the development of a methodology for the computationally efficient prediction of the dynamic response of structures with multiple joints. The first part of this thesis reports on the dynamic response of nominally identical beams with a single lap joint (“Brake-Reuss” beam). The observed impact responses at different levels clearly demonstrate the occurrence of both micro- and macro-slip, which are reflected by increased damping and a lowering of natural frequencies. Significant beam-to-beam variability of impact responses is also observed. Based on these experimental results, a deterministic 4-parameter Iwan model of the joint was developed. These parameters were randomized following a previous investigation. The randomness in the impact response predicted from this uncertain model was assessed in a Monte Carlo format through a series of time integrations of the response and found to be consistent with the experimental results. The availability of an uncertain computational model for the Brake-Reuss beam provides a starting point to analyze and model the response of multi-joint structures in the presence of uncertainty/variability. To this end, a 4-beam frame was designed that is composed of three identical Brake-Reuss beams and a fourth, stretched one. The response of that structure to impact was computed and several cases were identified. The presence of uncertainty implies that an exact prediction of the response of a particular frame cannot be achieved. Rather, the response can only be predicted to lie within a band reflecting the level of uncertainty. In this perspective, the computational model adopted for the frame is only required to provide a good estimate of this uncertainty band. Equivalently, a relaxation of the model complexity, i.e., the introduction of epistemic uncertainty, can be performed as long as it does not affect significantly the uncertainty band of the predictions. Such an approach, which holds significant promise for the efficient computational of the response of structures with many uncertain joints, is assessed here by replacing some joints by linear spring elements. It is found that this simplification of the model is often acceptable at lower excitation/response levels. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2016

Made available in DSpace on 2014-06-11T19:28:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-12-15Bitstream added on 2014-06-13T18:57:54Z : No. of bitstreams: 1 arbex_aa_me_guara.pdf: 3130393 bytes, checksum: e1c62358ab112fd781ed4b9dfabf900d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Juntas rebitadas sobrepostas representam elementos críticos na construção de estruturas aeronáuticas quando projetadas à fadiga. Por serem elementos de fixação largamente utilizados na indústria aeronáutica, o estudo de suas propriedades e variáveis à fadiga tem sido cada vez mais amplo. A variável que tem mostrado possuir alta influência na resistência à fadiga de juntas rebitadas é a força de aperto aplicada no processo de rebitagem. A vida da peça tende a ser maior quando o valor dessa força é aumentado. O método dos elementos finitos, que é uma ferramenta de cálculo aplicada nos mais diversos campos de atuação e tem se tornado parte indispensável de projetos mecânicos, é utilizado nesta dissertação para a análise de uma junta rebitada sobreposta de uso aeronáutico. A junta é simulada levando em conta as etapas do processo de fabricação e aplicação, a fim de realizar a análise de seu comportamento mecânico e calcular sua vida em fadiga. Através de um teste experimental de tração monotônica foram obtidos valores de deformação com extensômetros, e é feita a correlação desses dados com o modelo numérico a fim de validar a modelagem. Em seguida são feitas mais duas análises com diferentes forças de aperto, com o objetivo de verificar a influência dessa variação na vida em fadiga da peça. / Riveted lap joints represent a critical element in metallic airframe construction when designing against fatigue. These elements are widely used in the aerospace industry, so the study of the fatigue’s properties and variables has been increasingly broad. The variable that has shown to have a high influence on the fatigue strength of riveted joints is the clamping force applied to the riveting process. The life of the part tends to be higher when the clamping force applied is increased. The finite element method, which is a calculation tool applied in various fields of activity and has become an indispensable step of mechanical design, is used in this dissertation for the analysis of a riveted lap joint of aeronautic use. The joint is simulated considering the stages of the manufacturing process and application, in order to perform analysis of mechanical behavior and calculate the fatigue life. Through an experimental test of monotonic tensile, strain values were obtained with strain-gauges, and is made the correlation of these data with the numerical model to validate the modeling. Finally two more tests are made with different clamping forces, in order to check the influence of this variation in fatigue life of the joint.

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