Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14575号 / 工博第3043号 / 新制||工||1453(附属図書館) / 26927 / UT51-2009-D287 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 落合 庄治郎, 教授 粟倉 泰弘, 准教授 奥田 浩司 / 学位規則第4条第1項該当

[pt] O presente trabalho tem como principais objetivos estudar a formulação do método dos elementos de contorno e implementar um programa computacional para análise de tensões de problemas bi-dimensionais (estado plano de deformação e axissimetria) considerando também a possibilidade de acoplamento dos métodos dos elementos de contorno (MEC) e dos elementos finitos (MEF). Dentro deste estudo são abordados as soluções fundamentais para materiais linearmente elásticos, a formulação das integrais no contorno, as técnicas para tratamento de singularidade, a utilização de nós duplos para estudos de canto, etc. Os resultados numéricos obtidos em alguns problemas bi-dimensionais pelos métodos dos elementos de contorno e dos elementos finitos, considerando isoladamente ou acoplados, são comparados mutuamente e com soluções analíticas da teoria da elasticidade linear. Vantagens e desvantagens destes métodos, bem como dificuldades de implementação numérica, são discutidas ao longo deste trabalho. / [en] The main objectives of this work are the study of the boundary element formulation as well as the implementation of computer program for stress analyses of bidimensional problems under axisymmetric or plane strain conditions. The computer program also combines the boundary element method (BEM) with the finite element method (FEM) thus permitting its application to wide range of geotechnical problems. In this study research several mathematical aspects of the boundary element method are reviewed, such as the fundamental solutions for elastic materials, contour integration, singularities, corner problems, etc. The numeric results obtained in some 2D problems the BEM and FEM, in a coupled or isolated form, are compared with analytical solutions provided by classical theory of elasticity. Advantages and shortcomings of both methods, as well as the difficulties in the computer implementation, are also discussed in this work.

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Mathematical models of heat flow and elastic stress generation based on the finite-element method have been developed and utilized to analyze the Epic-3 Monofrax-S casting process (Monofrax-S is primarily composed of 47-57% A1₂O₃, 34-41% ZrO₂ and 10-15% SiO₂). The results of the mathematical analysis, in conjunction with information obtained from a comprehensive industrial study, has led to the development of mechanisms for the formation of the various crack types found in this casting process. Thermal stresses have been predicted to be generated early in the solidification process in association with rapid cooling of the refractory surface as it contacts the initially cool mould and again later in the solidification process in conjunction with the tetragonal-to-monoclinic phase transformation which occurs in the zirconia component of Monofrax-S. The mathematical analysis has also helped to identify indirectly a potential mechanism for the generation of mechanical stresses. Based on an understanding of the generation of tensile stresses, recommendations have been made for modifications to the moulding and casting procedures in order to reduce the propensity for the formation of cracks. The modifications have included changes to the mould construction and geometry to reduce the generation of mechanical stresses and changes to the moulding materials to impact on the flow of heat at key times during solidification and cooling. With the recommendations in place, the casting process has been re-examined with the mathematical models to verify the impact of the modifications. The predictions show that the modifications have acted to reduce tensile stresses associated with the formation of Type-A and -B cracks. Preliminary industrial trials with the modified mould have yielded blocks free of these defects. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

[pt] Este estudo é uma investigação experimental das vibrações flexurais de uma viga em balanço causadas por impactos axiais.Uma série de medidas foi feita usando-se uma viga de aço inoxidável submetida a impactos de diferentes magnitudes,aplicados através de um arranjo massa-pêndulo. A amplitude dos impulsos foi variada mudando-se o peso e o ângulo de lançamento da massa do pêndulo. Para a gama e a característica dos impactos utilizados nesta investigação,concluímos que a amplitude dos impulsos aplicados é o parâmetro relevante da resposta transversal da viga. As máximas tensões de flexão e os máximos deslocamentos laterais relacionam-se linearmente com a amplitude dos impulsos axiais aplicados.Não foi observada nenhuma instabilidade dinâmica,no sentido de deslocamentos laterais excessivos, na gama de impulsos utilizados nessa pesquisa. / [en] This study is an experimental investigation of the dynamic response of a cantilever beam due to axial impact. A series of response measurements were made for a cantilevered stainless steel beam subjected to impulses of different magnitudes.The impulses were produced by a pendulum-impact mass arrangement and their magnitudes were varied by changing the weight and release angle of the pendulum mass. For the range and character of impulses utilized in this investigation,it is concluded that magnitude of the applied impulse is the relevant parameter for the transverse response of the beam.Moreover,both maximum bending stresses in the beam and its maximum lateral displacements were found to be linearly related to the magnitude of the applied axial impulses. No dynamic instabilities,in the sense of excessive lateral displacements of the beam, was observed for the range of impulse magnitudes selected here.

The master thesis focuses on the strength calculation of piping with extra consideration given to the local effects of thermal loads. To be recognized as properly functioning, the piping is required to withstand the expected operating conditions in order to enable the continuous transport of the working fluid within the interconnected devices. It is imperative to take into consideration the variable thermal load in the area where the individual pipe branches connect into the main transmission piping. A major part of the thesis is concerned with the assessment of the expected workload influence on the most stressed parts of the system. The data are gathered by employing temperature and stress-strain analyses carried out in the ANSYS Mechanical program using the finite element method. The values based on the analyses are cross-checked with both the permitted values according to the ASME standard B31.3 Process piping and the ASME Boiler and Pressure Vessel Code stress categorization method. Since all the evaluated stresses are below their respective permissible values, the piping strength is concluded as satisfactory according to the standards.

The main aim of the this diploma thesis is the wing design of the UAV aircraft, including the appropriate material choice, calculation of the wing load and also strength analysis. Other goals include the design of the location and volume of fuel tanks, as well as the design of wingspan reduction after landing.

Load calculation wing, aileron, flaps, tail unit of Parrot Aircraft according to specification ASTM F 2245-04. Stress analysis coat, stem, flange, rivet and point.

Presented work deals with the strain-stress analysis of a spinal segment while monitoring the influence of total disk replacement Maverick on the global behaviour of the spinal segment. It also assesses the influence of this implant on the nearest upper intervertebral disk. On the basis of CT images was in the program Rhinoceros created the geometry model of spinal segment Th12-L2. The geometry model of implant was applied between vertebra L1 and L2 instead of intervertebral disk from which the whole core was removed, while in the immediate surrounding of implant the part of disk was left, which is important from the view of stability. Subsequently were in the program Ansys Workbench created finite element models for two states: - healthy (unbroken) status - status with applied implant Then the calculations for movements were realized: lateral flexion, flexion, extension, rotation. For the same movements were realized calculations of the model simulated spinal fusion of the vertebras L1-L2. Finally an influence both of methods (total disk replacement, spinal fusion) on the intervertebral disk Th12-L1 was compared.