For the last decades usage of aluminium alloys have been increasing tremendously. They have been used in aerospace industry widely and now aluminium alloys are becoming more and more popular in automotive and defense industries. Consequently / successful welding of aluminium alloys gains importance. In this study a research is carried out on eldability of plates having different thicknesses of composition 5754 aluminium and 6063 aluminium in T-fillet geometry using Gas-metal Arc Welding technique. It was aimed to have a successful joint without using pre-weld and post-weld heat treatments. During tests welding current and voltage were the varying parameters as welding speed was held constant. Macro-examinations were performed to see the penetration of the weld metal. It was seen that the type of filler wire greatly effects weld penetration. Hardness tests, tensile tests were done to compare the mechanical properties of the welded joints with different filler wires. Despite having better penetration in 4043 filler wire used weld joints, 5356 filler wire used weld joints had higher tensile strength and ductility. In the second part of the study, a dynamic loading machine was designed and manufactured to see the behavior of the fillet welds under dynamic loading. The amount of stress and strain given to the specimen on this machine was adjustable but can&rsquo / t be measured. The tests that were made with this machine aimed only to compare the number of cycles of specimens before fracture. For dynamic loading tests two groups of specimens were prepared with filler wire 4043 / each group having been welded with different heat inputs. It was aimed to see the effect of welding heat input on service lifes but no significant difference between cycle numbers of specimen groups having been welded with different heat inputs was observed. Microstructure examinations of these specimens revealed that coarsening the grains, grain boundaries, particles in PMZ and HAZ regions between Al 6063 base metal and weld zone made these areas more susceptible and favorable for crack propogation than Al 6063 base metal.

Neste trabalho, é apresentado um modelo aperfeiçoado para gerar carregamentos dinâmicos pseudo-aleatórios para modelos estruturais sob excitação sísmica e de vento. Este é baseado no modelo de vento sintético proposto por Franco, diferindo pelo fato que usa a transformada de wavelet harmônica ao invés da série de Fourier, pois tem como objetivo descrever um comportamento não estacionário com a ajuda de uma função temporal. Para testar a qualidade do sinal desenvolvido neste trabalho, este foi comparado com sinais verdadeiro, das acelerações de sismos ocorrido na cidade de Hachinohe, no Japão e em El-centro, na Califórnia, e com um sinal gerado pelo modelo do sismo sintético de Corbani, este também baseado no modelo de vento sintético, com o uso de séries de Fourier. Em todas as análises feitas, foi mostrando que embora a geração de carregamentos com transformadas de wavelet harmônica seja mais complexa, esta possui um bom potencial para gerar carregamentos mais próximos da realidade do que métodos usuais baseados em carregamentos estacionários. / In this work is intruduced a improve model to create random loads to use in structural models under sismic and wind disturbance. The model is based on synthetic wind model intends by Franco, differing by the fact that applies harmonic wavelet transform instead of Fourier series, because it has the goal to describe a non stationary behavior with temporal function support. To test the quality from the signal developed in this work, it has been analyzed against true seismic acceleration signal that occurs from Hachinohe city in Japan and El-centro city in California, and with the synthetic seismic model developed by Corbani, that one descending on synthetic wind model, with Fourier series application. In all analysis, although loading creation with harmonic wavelet transform have been more sophisticated, that one has a great potencial to creat loading closer to the fact than usual methods based in stationary loading.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20760号 / 工博第4412号 / 新制||工||1686(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 杉浦 邦征, 教授 白土 博通, 教授 清野 純史 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The thesis focuses on investigating and optimizing a bushing script implemented as a tool in MSC ADAMS/Car. The study provides an insight on the representation of a rubber bushing and identify parameters which can be used to define the properties of a bushing in a simulation environment such as ADAMS/Car. The tool being studied here can be used to implement different kind of bushings such as a hydro bushing and a general rubber bushing, but optimization was implemented for the rubber bushing only. With an increasing reliance on Computer Aided Engineering (CAE) tools in the designing process, it is necessary that the vehicle behaviour can be predicted without relying on physical testing. CAE tools reduces the need of prototypes and provides a faster approach to designing vehicles. MSC ADAMS/Car is one such tool, which has been used here to predict the vehicle dynamic behaviour, which will influence the ride, handling and comfort characteristics of the vehicle. Rubber bushings, which have been studied here, have a significant contribution to the overall stiffness of the vehicle and as such, it is imperative that the tool being used here, is accurate and makes the designing process easy. The rubber bushing can be imagined to be a combination of a non-linear elastic spring, a frequency dependent Maxwell component and an amplitude dependent frictional element. In order to ease the design of the bushing properties, a reduced number of input properties are used to calculate the bushing properties internally. While trying to validate the force hysteresis loop obtained through the model with the measured data, it was seen that the accuracy was quite poor for the model when loading it with dynamic loads corresponding to amplitudes of0.2 mm and lower. The quasi-static loading and dynamic loading above 0.2 mm is shown to have a satisfactory accuracy when compared to the measured data.

The response of submerged structures subject to loading by underwater blast waves is governed by complex interactions between the moving or deforming structure and the surrounding fluid and these phenomena need to be thoroughly understood in order to design structural components against underwater blast. This thesis has addressed the response of simple structural systems to blast loading in shallow or deep water environment. Analytical models have been developed to examine the one-dimensional response of both water-backed and air-backed submerged rigid plates, supported by linear springs and loaded by underwater shock waves. Cavitation phenomena as well as the effect of initial static fluid pressure are explicitly included in the models and their predictions were found in excellent agreement with detailed FE simulations. Then, a novel experimental apparatus has been developed, to reproduce controlled blast loading in initially pressurised liquids. It consists of a transparent water shock tube and allows observing the structural response as well as the propagation of cavitation fronts initiated by fluid-structure interaction in a blast event. This experimental technique was then employed to explore the one-dimensional response of monolithic plates, sandwich panels and double-walled structures subject to loading by underwater shock waves. The performed experiments provide great visual insight into the cavitation process and the experimental measurements were found to be in good agreement with analytical predictions and dynamic FE results. Finally, underwater blast loading of circular elastic plates has been investigated by theoretically modelling the main phenomena of dynamic plate deformation and fluid-structure interaction. In addition, underwater shock experiments have been performed on circular composite plates and the obtained measurements were found in good correlation with the corresponding analytical predictions. The validated analytical models were then used to determine the optimal designs of circular elastic plates which maximise the resistance to underwater blast.

Um número significativo de pontes têm sido construídas na forma de grelhas de vigas pré-moldadas, sobre as quais apoiam-se pré-lajes com posterior concretagem de capa, finalizando a execução das lajes das mesmas. Esse processo construtivo tem sido largamente utilizado tendo em vista a racionalização da construção dispensando o uso de cimbramentos, abreviando consideravelmente os prazos de construção e consequentemente reduzindo os custos. Todavia no desenvolvimento do projeto, sabe-se que essas lajes são elementos altamente suscetíveis à fadiga e, tendo-se em vista a existência de concretagem em duas etapas (pré-laje e capa final) e concretos de idades diferentes, geram-se dúvidas obre o comportamento desta interface com relação às cargas dinâmicas atuantes no decorrer da vida útil da obra. A escassez de estudos ou pesquisas relacionadas a essa questão, levaram à realização do presente trabalho, de cunho experimental, e com o objetivo de se estudar o comportamento desses elementos submetidos às cargas de fadiga e as suas resistências finais no que se refere às cargas de ruptura antes e depois de fatigadas. Foram ensaiadas 9 lajes de concreto sendo 6 lajes com rugosidade normal (saliência dos agregados brita 1) e 3 com baixa rugosidade (alisamento com espátula de madeira). Não foram identificadas rupturas por fadiga e a resistência das lajes fatigadas se mantiveram, quando levadas a ruptura no final dos ensaios, no mesmo nível daquelas não fatigadas. / A significant number of bridges have been built in the form of grids of pre-cast beams on which pre-slab are supported, with posterior concreting of concrete cover, completing the execution of the slabs. This construction process has been widely used in order to rationalize the construction without shoring, shortening considerably the time of construction and thereby reducing costs. However in developing the project, it is known that these slabs are elements highly susceptible to fatigue and, keeping in mind the existence of concrete in two stages (pre-slab and final cover) and different ages, doubts about the behavior of this interface with respect to dynamic loads acting over the lifetime are generated. The scarcity of studies and researches related to this issue led to the realization of this experimental work, in order to study the behavior of these elements subjected to fatigue loading and their final resistance in relation to the failure load before and after fatigue loading. Tests were made in 9 concrete slabs, 6 with usual surface roughness (salience of crushed aggregates 1) and 3 with low roughness (smoothing with wooden spatula). It was verified that no rupture due to fatigue loading were identified and the resistance of the slabs submitted to fatigue loading remained on the same level of those not fatigued, when carried to cracking at the end of the tests.

As lajes dos tabuleiros de pontes de concreto armado, sejam elas maciças ou executadas com pré-lajes, são elementos estruturais suscetíveis à fadiga, devido às ações a que são submetidas. As pré-lajes, pelo fato de serem resultantes da junção de dois concretos diferentes, torna-se ainda mais suscetível à fadiga. Este trabalho apresenta estudos, ensaios e análise de resultados a respeito do comportamento à fadiga das lajes de pontes de concreto, sejam as maciças ou as executadas com pré-laje, armadas com barras ou telas soldadas. Foram realizados ensaios de fadiga de barra ao ar CA50 f10 mm isoladas e em telas para a construção da Curva de Wöhler nas condições brasileiras. Além disso, foram ensaiadas 23 lajes de concreto, sendo 6 lajes maciças e 17 executadas com prélajes, montadas com diversas configurações de armadura, submetidas a ensaios estáticos e dinâmicos. As configurações de armaduras adotadas nas lajes da pesquisa foram baseadas nas utilizadas com freqüência neste tipo de elemento das pontes, escala ½. Um dos principais motivos que levaram ao desenvolvimento desta pesquisa de caráter experimental foi a escassez de dados sobre o comportamento de lajes armadas com barras ou telas soldadas de fabricação brasileira, submetidas a ações cíclicas. Outro motivo foi a carência de estudos a respeito da iteração prélaje x capa. Foi verificado que não houve ruptura nessa região da estrutura devido aos carregamentos cíclicos aplicados no meio do vão. Ficou evidenciado também que as soldas das telas afetam sua resistência à fadiga. / Concrete bridge slabs, massive or pre-slabs, are structural elements susceptible to fatigue, due to loading applied to them. Pre-slabs, result of two different concretes, become even more susceptible to fatigue. This research presents the studies, tests and analysis of the results about the behavior of concrete bridge massive slabs or pre-slabs reinforced with steel bars and welded steel meshes due to fatigue loading. Axial testing in air of CA50 f10 mm in continuous bars and steel meshes were made in order to build the Wöhler Curve to the Brazilian conditions. Besides that, tests were made in 23 concrete slabs, 6 massive slabs and 17 preslabs, with several reinforcements arrangements, submitted to static and dynamic loading. The reinforcement configurations adopted in the slabs were based on the commonly used in these bridge elements in scale ½. One of main reasons that lead this experimental research development was the scarcity of data about the behavior of concrete slabs reinforced with rebars and welded mesh made in Brazil, submitted to cycle loading. Another reason was the lack of studies about the iteration between pre-slab and concrete cover. It was verified that no rupture was found in this region of the structure due to midspan cycle loading. The welding process caused loss of fatigue resistance.

Um ensaio de carga dinâmica pode ser efetuado em tubulões, estacas hélice continua, estacas moldadas in situ ou estacas cravadas. Tal ensaio se baseia na Teoria da Propagação de Onda em estacas e visa avaliar a capacidade de carga estática mobilizada a partir do evento dinâmico. A análise do ensaio é feita mediante um programa (p.e. CAPWAP ou DLTWAVE), computacional que leva em conta tanto os sinais de força e velocidade obtidas em campo e o modelo do sistema estaca-solo Este trabalho apresenta uma metodologia para atualização bayesiana dos parâmetros de Smith da teoria de propagação de onda, levando em conta não só os sinais registrados, mas também a informação geotécnica-probabilista prévia sobre estes parâmetros. Uma aproximação semelhante já foi aplicada pelo orientador da pesquisa à estimativa de parâmetros geotécnicos de rochas a partir de medidas de deslocamento em túneis, e de campos de permeabilidade a partir de observações piezométricas em barragens. A técnica proposta está baseada firmemente em conhecimento empírico geotécnico que fornece o ensaio e erro do procedimento usual de comparação de sinais: a atualização bayesiana permite aos parâmetros afetados por incerteza maior ter um ajuste proporcionalmente maior de acordo com observações. O máximo deslocamento elástico (quake), o fator de amortecimento (damping) e a resistência estática unitária, de cada trecho da estaca, são considerados variáveis aleatórias com distribuições prévias estimadas dependendo do local de cravação da estaca. Discute-se e calcula-se a correlação cruzada entre parâmetros diferentes e autocorrelação ao longo de profundidade da estaca. As observações são escolhidas do sinal calculado por um software de análise de sinais de cravação, em espaços regulares ao longo do tempo. Postula-se um modelo linear de observação, pesquisa-se tal linearidade, também, deriva-se uma matriz de sensibilidade (ligando cada parâmetro a cada observação), e estimam-se também as incertezas nas observações (sinais). O resultado final é uma distribuição de parâmetros de Smith ao longo da profundidade de estacas, atualizada de acordo com as observações. A aproximação proposta é aplicada em sinais de um dos momentos da cravação, no final da cravação (\'end of driving\', EOD). / An dynamic loading test can be performed in concrete piles, bored piles, drilled shafts, auger cast-in-place (continuous flight auger) piles. Such essay bases on the Theory of the Propagation of Wave in piles with the aim of evaluate the capacity of static load mobilized from the dynamic event. The analysis of the test is made by a PC program (p.e. CAPWAP or DLTWAVE), that takes into account the signals of force and velocity obtained in field and the pile-soil model. This work presents a methodology for bayesian updating of Smith\'s parameters, taking into account not just the recorded signals, but also the prior geotechnical-probabilistic information about these parameters. A similar approach has already been applied by the senior author to the estimation of rock geotechnical parameters from displacement measurements in tunnels, and of permeability fields in embankment dams from piezometric observations. The proposed technique is deemed more firmly based on sound geotechnical knowledge than the usual trial and error signal matching procedure: bayesian updating allows for parameters affected by larger uncertainty to undergo proportionately larger adjustment according to observations. Quake, damping and static resistance are considered random variables, with prior distributions assessed from information about the geotechnical characteristics of the soils the pile is driven into. Cross-correlation between different parameters and auto-correlation along pile depth are discussed and estimated. Signals measured at some properly selected times are the chosen observations. A linear observation model, linking observations to parameters, is postulated, linearity is investigated, a sensitivity matrix (linking each parameter to each observation) is derived, and uncertainty in the observations (signals) is estimated. The final result is a distribution of Smith\'s parameters along pile depth, updated in accordance with the observations. The proposed approach is tested in end of driving (EOD) signal.

Apresenta-se o conceito de elemento isolado de fundação em tubulão, e analisa-se 10 provas de carga dinâmica de energia crescente, nos tubulões, considerando as provas de carga estática realizadas anteriormente nos mesmos. Os ensaios são realizados em tubulões a céu aberto, situados em maciço de solo da formação Rio Claro e Itaqueri, no campo experimental de fundações da USP/EESC. As análises baseiam-se em curvas de resistência x deslocamento e gráficos que mostram a evolução da resistência mobilizada com o aumento da energia aplicada, resultantes dos impactos do ensaio dinâmico de energia crescente (metodologia PDA e análises CAPWAP). Analisam-se também a influência da pré-inundação e da variação da sucção do maciço de solos nos ensaios dinâmicos, o efeito do reensaio e a variabilidade nos resultados de ensaios de investigação geotécnica (SPT e CPT), realizados no campo experimental. Os resultados das provas de carga dinâmica de energia crescente mostram que a resposta do sistema isolado de fundação em tubulão é diferente a cada nível de energia aplicada e que a história de carregamento do elemento isolado de fundação é de extrema importância para análise dos ensaios nele realizado. / The concept of an isolated foundation element in large diameter bored pile is presented and 10 dynamic loading tests with increased energy are analysed. The interpretation of the dynamic loading tests has been proceeded with due consideration of the results of static loading tests performed previously. The loading tests have been carried out in large diameter bored piles founded in Rio Claro and Itaqueri soil formation, situated in the experimental foundation field of USP/EESC. The analyses are based on resistance x displacement curves and selected graphics illustrating the development of mobilized resistance with increasing applied energy during a dynamic loading test (PDA methodology and CAPWAP type analysis). The influence of previous inundation in soil mass and suction variation are also analysed, as well as the effect of test repetition and variability in SPT and CPT results. The results obtained with the dynamic loading tests with increasing energy revealed a distinct behaviour of the isolated foundation system for each level of applied energy, showing that the loading history is an aspect of extreme relevance to an adequate analysis of the dynamic tests perfomed.

Esta tese aplica o conceito de energia complementar para a determinação da capacidade de carga última de estaca cravada no ensaio de carregamento dinâmico de energia crescente. O ensaio de carregamento dinâmico com impactos de energia constante só permite obter a resistência estática mobilizada do modelo de CASE ou de SMITH com base na teoria da equação da onda e no Pile Driving Analyzer. A aplicação de impactos de energia crescente mostra que a curva de resistência estática - deslocamento dinâmico apresenta: a) trecho linear crescente seguido de trecho que se curva até que a tangente se torna vertical ou b) trecho crescente quase linear até um pico de resistência, seguido de uma curva de descarga até um determinado valor que corresponde à tangente vertical ou, c) trecho linear crescente seguido de trecho curvo cuja tangente não se verticaliza e onde a resistência volta a crescer. A ruptura do sistema estaca - maciço de solos é caracterizada pela energia complementar que passa em um máximo sempre que a resistência mobilizada atinge um pico. No pós-ruptura o excesso de energia aplicada e o excesso de trabalho das forças de amortecimento do impacto, em relação ao pico máximo, crescem linearmente com o nível de energia cinética aplicada. / This thesis suggests how to evaluate the ultimate bearing capacity of driven piles by using dynamic load tests with increasing energy. The dynamic load test with constant energy blows only allows the determination of the mobilized static resistance (CASE and SMITH\'s model), by using the wave equation theory and the Pile Driving Analyzer. The application of increasing energy blows shows that this static resistance: a) increases with increasing energy and then becomes constant or; b) increases with increasing energy up to a peak resistance and thereafter first decreases and then becomes constant or, c) starts to increase with increasing energy, then remains constant and after some blows starts to increase again. lt is shown that the rupture of the pile-soil system is characterized by the kinetic complementary energy reaching an upper limit when the impact mobilizes the maximum static pile capacity. All the energy or work done by damping forces, in excess of this maximum or peak situation, increases linearly with increasing energy.