It was observed that the concrete is the most consumed material in the civil construction and not always satisfies all the demanded properties, its takes to researches that tries materials that can provide to the concrete more efficiency. This work, the discarding of residues procedures from the recycling of tires is focused, with the purpose to give to this material a rational destination, in the environment of the Civil Construction. The aim is to study the concrete behavior produced with rubber tire fiber addition, obtained by recycling of tire, and apply it on the confection of plates for to analyze the mechanical efforts behavior. The amongst of the additions are done in amongst usual for staple fibers. The bibliographical review disclosed that a reduction of the compressive strength when the rubber additions occurs. On the other hand, an increase of the ductility and the resistance for the impact occurs. The point of glow of the observed rubber was studied and it was observed that it occurs in a temperature range above of that one where the concrete has its deficit properties. With the short rubber fiber addition the same losses foreseen in literature without significant profits in the ductility are still verified. The rubber fibers chosen had been with low a relation length-diameter. This type for representing a small parcel and knowing that its separation can to add values that do not compensate its use as residue. Thus, it was considered that these results are satisfactory, a once that the possibility to include bigger rubbers fibers can increase the ductility. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Observando-se que o concreto é o material mais consumido na construção civil e que nem sempre satisfaz todas as características exigidas, busca-se experimentar materiais que possam proporcionar a ele mais eficiência. Neste aspecto, com foco no descarte de resíduos provenientes da reciclagem de pneus, de forma a dar a este material um destino racional, no ambiente da Construção Civil, foi objetivo deste trabalho estudar o comportamento do concreto com adição de fibras de borracha produzidas na recauchutagem do pneu, aplicando à confecção de placas pré-moldadas para analisar o seu comportamento diante de esforços mecânicos. Os teores das adições foram aqueles usuais para fibras (1%, 2%, 3%). A bibliografia revelou que ocorre uma diminuição da resistência à compressão do concreto com tais adições, por outro lado, ocorre um aumento da tenacidade e da resistência ao impacto. Com a adição de fibras curtas, ou seja, com uma baixa relação comprimento/diâmetro, verificam-se ainda as mesmas perdas previstas na literatura sem ganhos significativos na tenacidade. Escolheu-se este tipo por representar uma pequena parcela e verificar se a sua separação poderia comprometer a sua utilização como resíduo. Foi estudado ainda o ponto de fulgor da borracha e observado que este ocorre em uma faixa de temperatura muito acima daquela em que o concreto tem suas propriedades ameaçadas. Considerou-se que estes resultados são satisfatórios, uma vez que a possibilidade de incluir fibras maiores pode aumentar a tenacidade e recuperar a perda observada.

It was not thought that there would be some major flaws in the design of widely used steel moment frames until the Northridge Earthquake hit the California on January 17, 1994. Until then, steel moment frames were practiced as the most ductile system and were used in buildings from few stories to skyscrapers. The heavy devastation from Northridge Earthquake was an alarm for all the people related to the design and construction of such structures and pushed everybody to act fast to find some possible solutions to such never-expected-problems. Following the earthquake, FEMA entered into a cooperative agreement with the SAC joint venture in order to get a transparent picture of the problems in the seismic performance of steel moment frames and to come up with suitable recommendations. The research was specifically done to address the following things: to inspect the earthquake-affected buildings in order to determine the damage incurred in the buildings, to find out ways to repair the damaged buildings and upgrade the performance of existing buildings, and to modify the design of new buildings in order to make them more reliable for seismic performance. Among the various new design suggestions, the Reduced Beam Section (RBS) connection has been one of the most efficient and reliable option for high ductility demands. The purpose of this research was to study the behavior of concrete slabs in the performance of steel moment frames with reduced beam sections based on ductility, strength and stiffness. The slab is an integral part of a building. It is always wiser to consider the slab in order to assess accurately the seismic behavior of a building under the earthquake loading. In this research, two sets of finite element models were analyzed. Each set had one bare steel moment frame and one concrete slab frame which acted as a composite section. The connections were designed using the AISC Seismic Design manual (AISC 2012). The finite element modeling was done using NISA DISPLAY-IV (NISA 2010). All the models, with and without the slab were analyzed under the same boundary conditions and loads. Both non-linear and linear analyses were performed. The results from non-linear analysis were used to compare the ductility and strength whereas linear analysis results were used to compare the stiffness between bare steel and composite frame models.

Este trabalho, realizado em cooperação com a Gerdau Riograndense, tem por finalidade avaliar o comportamento do aço GG1013-M, um aço baixo teor de carbono microligado com vanádio e manganês, na laminação a quente no que tange a sua resistência à deformação, possibilitando assim a tomada de decisão em relação a modificações no processo. Foram realizados testes em simulador termomecânico Gleeble™ para determinação das temperaturas a serem usadas no teste prático no laminador, onde testou-se lotes que cobrissem toda a amplitude da faixa de composição química da qualidade do aço em estudo. No teste prático no laminador, foram retiradas amostras para os ensaios mecânicos, onde identificou-se, por intermédio do tratamento de dados em software estatístico, a influência da variação dentro da faixa da composição química sobre os limites de escoamento e resistência. Como resultado, conseguiu-se determinar a faixa de temperatura mais provável, onde a resistência a deformação a quente é menor, minimizando ou eliminando as conseqüências da redução de ductilidade a quente por conta do endurecimento da matriz por precipitação dos elementos de liga em forma de compostos. / This work was conducted in cooperation with Gerdau Riograndense aiming at the evaluation of the hot rolling behavior of a low carbon steel microalloyed with manganese and vanadium (internally GG1013-M steel).The deformation resistance was evaluated, allowing for the decision in relation to changes in the process. A thermomechanical simulator GleebleTM was used to determine the temperatures to be used in practical tests in the rolling mill, where it was tested different material batches covering the large range of chemical compositions for this kind of steel. Mechanical tests were performed on samples taken from the practical tests in the rolling mill. From this tests the influence of chemical composition variation on the yeld strength and maximum stress was studied. As a result, we were able to determine the most likely range of temperatures for a minimization of hot strentgh, therefore also minimizing or eliminating the consequences of the reduction in the hot ductility due precipitation hardening of the matrix.

Orientador: Mônica Pinto Barbosa / Banca: Tulio Nogueira Bittencourt / Banca: Rogério de Oliveira Rodrigues / Resumo: Apresenta-se como objeto desta pesquisa o estudo numérico não-linear da ductilidade de vigas de concreto armado convencional e de alto desempenho. Toda a análise numérica é efetuada no código de cálculo baseado no método dos elementos finitos CASTEM 2000, que utiliza o modelo reológico elastoplástico perfeito para o aço, o modelo de Drucker-Prager para o concreto e o método de Newton-Raphson para a solução de sistemas não-lineares. O núcleo deste trabalho concentra-se na obtenção de curvas força - deslocamento e momento - curvatura com a finalidade de quantificar respectivamente os índices de ductilidade global e local das vigas analisadas. De início, confrontam-se as respostas numéricas obtidas com resultados experimentais fornecidos pela literatura a fim de garantir confiabilidade à análise numérica realizada. Posteriormente, efetua-se a determinação da capacidade de deformação inelástica do elemento estrutural em questão, variando-se a resistência à compressão do concreto, a taxa geométrica de armadura longitudinal de tração, a tensão de escoamento das armaduras, o espaçamento entre estribos, a base da seção transversal do elemento estrutural e o efeito escala. Estes parâmetros foram avaliados para dois casos de solicitação: flexão simples tipo I e flexão simples tipo II. O primeiro caso caracteriza-se pela ação de forças simétricas aplicadas à 1/3 e 2/3 do vão e a segunda por uma força centrada no meio do vão. A linha de tendência geral observada foi de uma maior ductilização das vigas sujeitas à flexão simples tipo II, em detrimento às solicitadas por flexão simples tipo I. Quanto ao efeito escala observa-se que a ductilização das vigas é inversamente proporcional à esbeltez das mesmas. / Abstract: The objective of this thesis is the study of the ductility of high and conventional strength reinforced concrete beams by non-linear numerical simulations. The numerical analysis is based on the finite element method implemented in CASTEM 2000. This program uses the constitutive elastoplastic perfect model for the steel, the Drucker-Prager model for the concrete and the Newton-Raphson for the solution of non-linear systems. This work concentrates on the determination of force - displacement and moment - curvature curves with the purpose of quantifying the global and local ductility indexes of the beams. First, the numeric responses are confronted with experimental results found in the literature in order to check the reliability of the numerical analyses. Later, a parametric study is carried on. The inelastic deformation capacity of the structural element is investigated by varying the concrete compressive strength, the longitudinal reinforcement ratio, the yield stress of the reinforcement, the spacing between stirrups, the member section dimensions and the element size. These parameters have been analyzed for two cases: simple type I and simple type II bending. The first case is characterized by the action of applied symmetrical forces to the 1/3 and 2/3 of the beam size and second for a force centered in the middle of the beam size. The general tendency observed points to a high ductilization of the beams subjected to simple type II bending in comparison to the ones subjected to simple type I bending. With respect to the element size, it is noticed that the ductility of the beams is inversely proportional to their slendernesses. / Mestre

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-10Bitstream added on 2014-06-13T18:31:07Z : No. of bitstreams: 1 jacomassi_lmc_me_ilha.pdf: 1853171 bytes, checksum: f9955a37141d1b46cbca1dacc35af9be (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A demanda crescente pela utilização de Concreto de Alta Resistência (CAR) torna necessária a definição de critérios e procedimentos de análise do comportamento estrutural desse material. Nesse sentido, este trabalho apresenta a discussão de resultados experimentais publicados e as simulações numéricas de pilares armados de CAR submetidos à compressão axial simples. Utilizando o Código CASTEM 2000, é feita uma modelagem numérica bidimensional e análise via Método dos Elementos Finitos (MEF) para a reprodução dos diagramas força-deformação obtidos experimentalmente. Após um estudo comparativo dos parâmetros recomendados por normas internacionais de análise do comportamento estrutural do CAR, nota-se que os resultados numéricos obtidos utilizando as especificações da Norma Norueguesa NS 3473 são mais próximos dos experimentais. A modelagem numérica desenvolvida é capaz de reproduzir, com certa precisão, a capacidade de carga de pilares de diversas geometrias, taxas de armadura transversal e longitudinal, tipos de aço e resistência do concreto variando entre 50 MPa e 90 MPa. As taxas mínimas de armadura capazes de promoverem a ductilização dos pilares por desagregação do cobrimento são superiores a 2,5% de armadura longitudinal e 2,0% de armadura transversal, segundo os resultados experimentais. Comparando a esses resultados os obtidos pelas simulações, observa-se como de comportamento dúctil os pilares com capacidade de carga obtida numericamente pelo menos 25% maior que a força máxima teórica obtida de acordo com as recomendações da NS 3743. / The increasing demand of the use of High-Strength Concrete (HSC) makes it necessary to define criteria and procedures analysis to the structural behavior of this material. This work presents the discussion on published experimental results and numerical simulations of HSC reinforced columns submitted to simple axial compression. Bidimensional numerical modeling with Finite Elements Method (FEM) analysis were made to reproduce experimentally force-strain diagrams by using the Code CASTEM 2000. After a comparative study on the internationally recommended HSC structural behavior analysis standards, it may be inferred that the numerical results obtained using specifications of the Standard Norge NS 3473 are the closest to the experimental ones. The adopted numerical modeling could reproduce the force capacity of columns of different shapes, transversal and longitudinal reinforcement rates, types of steel and concrete resistance from 50 MPa to 90 MPa with some precision. The minimal reinforcement rate able to provide columns ductility by confinement effect is higher than 2.5% longitudinal reinforcement and 2.0% transversal reinforcement, according the experimental results. Comparing these results with the simulations, it could be considered the ductility behavior of the columns with the numerical charge capacity at least 25% higher than the maximum teorical force obtained according to recomendations of NS 3743.

Made available in DSpace on 2014-10-09T12:53:35Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:29Z (GMT). No. of bitstreams: 1 12220.pdf: 3040591 bytes, checksum: cf07d18c47b6b9bc7f1a361b3a6fe286 (MD5) / Dissertação (Mestrado) / IPEN/D / Universidade Mackenzie. Departamento de Engenharia de Materiais, São Paulo

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2011 / Smart (SMA-Shape Memory Alloy) Technology continues to advance rapidly as engineers move closer to and understand better the industrial and commercial needs for SMA. As a matter of fact, all types of products, which exercise some type of control over their function, are rapidly making their way into the marketplace [36] Nonetheless, nowhere has been evidence in the development of a SMA impeller. Unlike traditional impellers with no control over their function and sometimes fixed angle of attack, this paper demonstrates numerical investigations using analytical algorithms (Matrix laboratory programming and excel spread sheet) and advanced computer simulation package, Engineering Fluid dynamics (EFD) into the feasibility of using a smart impeller to study the performance of a pumping system and the best angle of attack for a Shape Memory Impeller. Primarily, Bench mark data and dimensions are obtained from a standard centrifugal pump run on a FM21 demonstration unit. Using the same standard centrifugal pump, and keeping all other dimensions the same but altering the angle of attack, EFD simulations where made. From analytical algorithm and EFD comparison, it was evident that the best angle of attack is 12 degree at the outlet angle with respect to the inlet angle. From EFD results, it is palpable that, by increasing the angle of attack from 35 degree to 45 degree at the outlet there will be huge increase in flow rate by 63.47% There is also a slight decrease in the impeller Torque from 35 degrees to 42 degrees by 0.72%. It is economically feasible to work at an outlet angle of 42 degrees due to increase in efficiency of 62.1% and a drop in torque of 0.72% by varying the outlet angle from 35 degrees to 42 degree. Understanding how critical actuator design is, it should be suggested that any shape memory impeller should never be used in critical components without a prior history of thermal and mechanical loading. Therefore, a NiTi impeller constitutive model can be designed, with impeller blades made from NiTi plates, trained to remember its best angle of attack (Martensitic phase). NiTi shape memory metal alloy (plates-blades) can exist in a two different temperature-dependent crystal structures (phases) called martensite [9](lower temperature-normal pumping condition) and austenite [9] (higher temperature or parent phase-trained best angle of attack.)

abstract: With increasing concerns of the intrinsic toxicity of lead (Pb) in electronics, a series of tin (Sn) based alloys involving silver (Ag) and copper (Cu) have been proposed as replacements for Pb-Sn solder and widely accepted by industry. However, they have a higher melting point and often exhibit poorer damage tolerance than Pb-Sn alloys. Recently, a new class of alloys with trace amount of rare-earth (RE) elements has been discovered and investigated. In previous work from Prof. Chawla's group, it has been shown that cerium (Ce)-based Pb-free solder are less prone to oxidation and Sn whiskering, and exhibit desirable attributes of microstructural refinement and enhanced ductility relative to lanthanum (La)-based Sn-3.9Ag-0.7Cu (SAC) alloy. Although the formation of RESn3 was believed to be directly responsible for the enhanced ductility in RE-containing SAC solder by allowing microscopic voids to nucleate throughout the solder volume, this cavitation-based mechanism needs to be validated experimentally and numerically. Additionally, since the previous study has exhibited the realistic feasibility of Ce-based SAC lead-free solder alloy as a replacement to conventional SAC alloys, in this study, the proposed objective focuses on the in in-depth understanding of mechanism of enhanced ductility in Ce-based SAC alloy and possible issues associated with integration of this new class of solder into electronic industry, including: (a) study of long-term thermal and mechanical stability on industrial metallization, (b) examine the role of solder volume and wetting behavior of the new solder, relative to Sn-3.9Ag-0.7Cu alloys, (c) conduct experiments of new solder alloys in the form of mechanical shock and electromigration. The research of this new class alloys will be conducted in industrially relevant conditions, and the results would serve as the first step toward integration of these new, next generation solders into the industry. / Dissertation/Thesis / Ph.D. Materials Science and Engineering 2012

El Perú es un país sísmico debido que se encuentra cerca de una zona de Subducción donde la Placa de Nazca se mueve por debajo de la Placa Continental. En las llamadas zonas de subducción la placa acumula gran cantidad de energía al introducirse debajo de la otra, estas placas avanzan en sentido contrario comprimiéndose hasta llegar a un punto de ruptura de grandes volúmenes de roca generando sismos de gran magnitud. En Lima se han producido fuertes sismos según los registros que se tienen de la época siendo el más fuerte en el año de 1746 donde hubo mucha destrucción y muchas personas murieron. En el Perú se han desarrollado las normas E.060 Concreto armado y la E.030 Diseño Sismorresistente dentro del Reglamento Nacional de Edificaciones, estas normas son muy importantes para el diseño y buen comportamiento de las edificaciones. Las cuales se soportan en la cimentación, siendo ésta la encargada de transmitir las cargas al suelo distribuyéndolas de manera que no supere la presión admisible. El área de estudio que se va a analizar se encuentra ubicado en el distrito de Surquillo de la provincia y departamento de Lima, donde se está ejecutando el edificio multifamiliar “Floresty”, del cual nos interesa su cimentación y los muros para su análisis. El análisis se llevará a cabo con el programa VisualFEA. Este programa nos arrojará diferentes resultados a pesar de haber sido considerado el acero como elemento embebido. La aplicación del programa para obtener diferentes resultados es el fin de la presente tesina. Peru is a seismic country because it is near to a subduction zone where the Nazca Plate moves under the Continental Plate. In the denominated subduction zones, the plate accumulates a great amount of energy in getting into the other plate. These plates move forward to the contrary sense compressing themselves up to come to a break point of large volumes of rock generating earthquakes of great magnitude. In Lima, strong earthquakes have occurred according to records kept until now, and the most significant was that of 1746 where there were a lot of destruction and where many people died. In Peru, Reinforced Concrete E.060 and Earthquake Resistant Design E.030 Standards have developed in the National Construction Regulations. These standards are very important for designing and good building performance, which supports to the foundations, which is in charge of transferring the loads to the ground spreading these one so that it does not exceed allowable pressure. E.060 standard contains minimal values, which shall fulfill for structure performance with ACI momentum coefficient method. However, it is possible design with finite-element method using VisualFEA software and the results are obtained with this software shall fulfill the standard. The study area to analyze is within San Miguel District, Province and Department of Lima, where a multifamily apartment block is constructed, and we are interested in analyzing its foundation because it shows already a design given by projector; this design comes to be a pad foundation or foundation slab. It is from this item where we are going to start to proof it fulfills with ACI momentum coefficient method according to Peruvian Standard and it shapes with finite-element method through VisualFEA software whose results shall also fulfill. In this sense, the main objective would be comparison and demonstration of analysis results of building F’s foundation slab using finite-element method through VisualFEA software; these results shall fulfill the Construction E.60 Peruvian standard with the ACI momentum coefficients method.

Orientador: Antonio José Ramírez Londoño / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T12:50:46Z (GMT). No. of bitstreams: 1 UnfriedSilgado_Jimy_D.pdf: 31862670 bytes, checksum: f798572d3f744b9a4460a24f795ffa4d (MD5) Previous issue date: 2010 / Resumo: A fratura por queda de ductilidade (FQD) é um tipo de falha que ocorre em temperatura elevada e que afeta adversamente diversos materiais metálicos com estrutura cristalina cúbica de faces centradas (CFC), tais como, ligas de Níquel, Cobre e aços inoxidáveis. Na FQD é observada uma forte redução da ductilidade e a ocorrência de fratura intergranular no intervalo de temperatura homologa entre 0,4 e 0,8, e sob aplicação de esforços de tensão. Diversos autores têm proposto alguns fenômenos metalúrgicos, tais como o escorregamento ao longo dos contornos de grão e a precipitação de carbonitretos e carbonetos, como fatores que influenciam o comportamento da FQD em estrutura bruta de solidificação de ligas de Níquel. Não obstante, o mecanismo fundamental operante neste tipo de fratura ainda não está totalmente esclarecido. Neste trabalho é estudado o mecanismo operante na FQD em função do papel da precipitação de carbonitretos e das características microestruturais na estrutura bruta de solidificação de ligas Ni-Cr-Fe endurecidas por solução sólida. Foram fabricadas e avaliadas cinco ligas experimentais baseadas na composição da liga 690 com e sem adições de Nb, Mo e Hf, as quais foram projetadas com o suporte do método Calphad. A avaliação da FQD foi realizada a través da aplicação iterativa de técnicas de caracterização baseadas em microscopia eletrônica, combinada com a determinação experimental da energia de falha de empilhamento (EFE) usando radiação sincrotron e o uso de ensaio termomecânico in situ em temperatura elevada acoplado a um microscópio eletrônico de varredura (MEV), cujos resultados permitiram realizar mapeamento da deformação a partir de imagens digitais. O teste in situ facilitou o acompanhamento, em tempo real, do fenômeno de FQD dentro do intervalo de temperaturas entre 500 °C e 1000 °C, evidenciando a ocorrência de escorregamento ao longo dos contornos de grão, o que por sua vez permitiu a identificação das etapas do fenômeno com suas respectivas características. Nas ligas experimentais com adições de Nb e Hf foram obtidos contornos de grão fortemente ondulados devido à alta freqüência de precipitados primários intergranulares finos. A adição de Mo nas ligas experimentais juntamente com as adições de Nb e Hf contribuíram para uma forte diminuição da EFE. Os contornos de grão ondulados foram relacionados com o bloqueio mecânico do escorregamento que ocorre ao longo dos mesmos, como sugerido por diversos autores. A presença de Mo na rede cristalina e a baixa EFE contribuíram na restrição da mobilidade de discordâncias em temperaturas elevadas. As características anteriores foram relacionadas com o aumento da resistência a FQD. Finalmente, baseado na evidencia experimental obtida neste trabalho é proposto um mecanismo fundamental de ocorrência da FQD em estruturas brutas de solidificação por soldagem de ligas Ni-Cr-Fe similar ao mecanismo de fluência sem domínio da difusão com escorregamento ao longo dos contornos de grão proposto por Rachinger. / Abstract: Ductility-dip cracking (DDC) is a high temperature fracture phenomenon, which affects several face centered cubic (FCC) metallic materials, such as Nickel alloys, Copper alloys, and stainless steels. DDC is observed as a drastic reduction of ductility that leads to intergranular fracture at homologous temperature range between 0,4 and 0,8 under tensile stress. Diverse theories related to the grain boundary sliding and to carbides and carbonitrides precipitation were proposed to describe DDC behavior in Ni-alloys; however, the fundamental mechanism of DDC is not clear yet. In this work is investigated the fundamental mechanism of DDC, as well as the role of carbonitride precipitates and metallurgical characteristics on this phenomenon in aswelded solid-solution strengthened Ni-Cr-Fe alloys. Experimental alloys were designed by means of Calphad methodology using the alloy 690 chemical composition as the start point. Five compositions with Nb, Mo and Hf additions were subsequently fabricated and evaluated. The DDC evaluation was performed using electron microscopy characterization techniques, experimental measurements of stacking fault energy (SFE) using synchrotron radiation, and a scanning electron microscopy thermo-mechanical in situ test that allows a strain mapping from digital images. The in situ test has allowed obtaining at real time information about of DDC phenomenon on the temperature range between 500 °C and 1000 °C. Evidences of grain boundary sliding (GBS) were obtained through high temperature experiments, consequently allowing the recognition of DDC stages characteristics. Wavy grain boundaries were obtained in Ni-Cr-Fe alloys with Nb and Hf additions due to the high frequency and homogeneous distribution of fine intergranular primary precipitates. Mo, Nb, and Hf additions contributed for a perceptible SFE reduction. Several authors suggested that wavy grain boundaries block GBS, while the Mo presence in the crystal lattice leads to SFE reduction, which is related to the restriction of dislocations mobility at high temperature and to the increase of DDC resistance. Finally, a new fundamental mechanism of DDC is proposed based on experimental evidences for as-welded structures of Ni-Cr-Fe alloys, which is similar to the creep mechanism without diffusion, involving grain boundary sliding mechanism proposed by Rachinger. / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica