Gradientes térmicos induzidos no interior de componentes sujeitos a variações de temperatura durante o período de funcionamento podem provocar a ocorrência de tensões e deformações internas. A repetição destes ciclos térmicos pode causar a nucleação e a propagação de trincas por um processo denominado fadiga termomecânica. Este trabalho apresenta um estudo sobre o comportamento da liga de alumínio A356-T6, processada nas condições fundida e tixoextrudada, sob fadiga isotérmica e termomecânica. Foram realizados ensaios de fadiga de baixo ciclo isotérmica para as temperaturas de 120 e 280°C, e ensaios de fadiga termomecânica em-fase e fora-de-fase para a faixa de temperatura de 120 a 280°C. O material tixoextrudado apresentou melhor desempenho em fadiga nas condições isotérmica e anisotérmica (termomecânica) devido a uma microestrutura globular com menor nível de porosidade. / Thermal gradients induced in components during service under temperature changes can cause internal stresses and strains. This cyclic thermal behavior can cause crack nucleation and propagation under a process denominated thermomechanical fatigue. Permanent mold casting and tixoextruded A356-T6 aluminum alloy behavior under isothermal and thermomechanical fatigue was study in this work. Isothermal low cycle fatigue tests were performed in temperatures of 120 and 280°C. In-phase and out-of-phase thermomechanical fatigue tests were carried out in temperature range from 120 to 280°C. The tixoextruded material presented better isothermal and thermomechanical fatigue performance due to a globular microstructure and lower porosity level.

Made available in DSpace on 2014-06-11T19:27:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-09-03Bitstream added on 2014-06-13T18:31:04Z : No. of bitstreams: 1 yamasaki_mi_me_ilha.pdf: 16778400 bytes, checksum: 6afbdce5c51d7a7040bbcdba50a7949f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / É apresentado um estudo experimental da laminação de tiras fundidas a partir do material semi-sólido obtido na calha de resfriamento que alimenta continuamente um laminador duo. Os cilindros do laminador estão posicionados horizontalmente e podem ser operados na velocidade de 0,25 m/s, 0,47 m/s, 0,73 m/s e 1,07 m/s. A velocidade de 0,25 m/s produziu uma tira de melhor qualidade. Ligas hipoeutéticas Pb/Sn (Pb–30%Sn, Pb-40%Sn, Pb-50%Sn) e próxima ao ponto eutético (Pb-63%Sn), respectivamente, com intervalo de solidificação de 75 °C, 56 °C, 31 °C e 6 °C de acordo com o diagrama de fases, foram utilizadas nos ensaios experimentais para obter tiras semi-sólidas fundidas e tixoconformadas para comparação. As diversas simulações usando as ligas de Pb/Sn têm revelado a importância do intervalo de solidificação e temperatura de vazamento da liga, da velocidade dos cilindros, da temperatura do bocal junto ao cilindro inferior, da superfície de acabamento dos cilindros e da geometria da panela intermediária (tundish), sobre a qualidade do produto final. A liga Pb-30%Sn com alto intervalo de solidificação em comparação com outras ligas testadas, apresentou maior dificuldade para ser tixolaminada. Isso ocorreu, porque as ligas de alto intervalo de solidificação tendem a formar trincas à quente no final da solidificação. Como resultado, uma pasta metálica plástica é difícil de formar. O caminho provável para obter uma tira semi-sólida fundida de boa qualidade neste caso, é aplicar uma inoculação que produz grãos finos antes do vazamento. O controle para a tixolaminação empregando a liga Sn-37%Pb com intervalo de solidificação menor, e elevada fluidez, é mais rigoroso para obter uma tira contínua. Conseqüentemente, foram utilizadas diferentes temperaturas de vazamento (260, 240 e 220 ºC) para controlar a fluidez e obter o tempo de contato... / This is an experimental study of cast strip rolling from semi-solid material employing a cooling slope which continuously feeds a rolling mill. The cylinders of the rolling mill are positioned horizontally and can be operated at speeds of 0.25 m/s, 0.47 m/s, 0.73 m/s and 1.07 m/s. The lower speed of 0,25 m/s produces a strip of better quality. Hypoeutectic Pb/Sn alloys (Pb-30%Sn, Pb-40%Sn, Pb-50%Sn) and near eutectic point alloys (Pb-63%Sn), with solidification intervals of 75°C, 56°C, 31°C and 6°C respectively, according to the phase diagram, were used in experimental tests to obtain cast semi-solid and thixorolled strips for comparison. Simulations highlighted the necessary control parameters required to obtain good quality of the strip. These were: control alloy solidification interval, pouring temperature, roll speeds, ceramic nozzle temperature at the lower roll, quality of the roll surface finishing and tundish geometry. The Pb-30%Sn alloy, which has a much higher solidification interval in comparison with the other alloys tested, was difficult to thixoroll. This is because alloys with a high solidification interval tend to form hot tears at the end of solidification, and prevent a plastic metallic mush from forming. The probable solution to obtaining a semi-solid fused strip of good quality with this material, is to apply an inoculation that produces fine grains just before the pouring. In contrast, the parameter control for thixorolling of the Sn-37%Pb alloy, with lesser solidification interval and elevated fluidity, needed to be rigorous to obtain a continuous strip. Consequently, several pouring temperatures (260, 240 and 220ºC) were used to vary the fluidity and obtain sufficient alloy-inferior cylinder contact time for complete solidification. The strips obtained by the twin and single roll processing, and conventional rolling were characterized... (Complete abstract click electronic access below)

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DSSC est une technologie photovoltaïque de 3ème génération avec un fort potentiel économiquement et une efficacité importante de conversion des photons en électricité. Le DSSC à l'état solide à base d'électrolyte polymère solide prévient la perte et l'évaporation du solvant pendant la fabrication et le fonctionnement des cellules, ce qui prolongera efficacement la durée de vie de la cellule. Cependant, il souffre d'une faible conductivité ionique et d'une faible infiltration des pores.La présente thèse est dédiée au développement concomitant d'électrolytes polymères à base de polysiloxane d'un côté et de photoanodes TiO2 à porosité controlée de l'autre côté et leur incorporation dans des cellules solaires contrastants à l'état solide (ss-DSSC), dans le but d'améliorer leur efficacité photovoltaïque et la stabilité à long terme. À notre connaissance, les DSSC comprenant des couches de TiO2 bimodales et des électrolytes de polysiloxane n'ont jamais été rapportés.La conductivité ionique et le coefficient de diffusion des tri-iodures des liquides poly (ioniques) (PILs) à base de polysiloxane ont été largement améliorés par addition de liquides ioniques (ILs) ou de carbonate d'éthylène (EC), conduisant à des conductivités ioniques de l'ordre de 10-4 -10-3 Scm-1. Les DSSC fabriqués avec les électrolytes optimisés ont montré des rendements jusqu'à 6%, avec une stabilité à long terme pendant 250 jours.Des films de TiO2 bimodaux à double porosité (méso et macroporosité) ont été fabriqués par revêtement par centrifugation, en utilisant des modèles mous et durs. Les films à double matrice bénéficient d'une taille de pores accrue tout en maintenant une surface spécifique élevée pour l'adsorption de colorant. Les films bimodaux se sont révélés plus efficaces lorsqu'ils ont été testés avec des électrolytes polymères, ayant des efficacités comparables avec l'électrolyte liquide dans les DSSC, malgré une absorption plus faible de colorant.Cette thèse apporte une contribution significative dans le domaine des DSSC en tant que cellules solaires efficaces et stables qui ont été préparés à partir d'électrolytes polymères et de films bimodaux nouvellement synthétisés. / DSSC is a 3rd generation photovoltaic technology with potential to economically harvest and efficiently convert photons to electricity. Full solid state-DSSC based on solid polymer electrolyte prevents the solvent leaking and evaporation during cell fabrication and operation, which will effectively prolong the cell life time. However, it suffers from low ionic conductivity and poor pore infiltration.The present thesis is dedicated to the concomitant development of polysiloxane-based polymer electrolytes on one side, and TiO2 photoanodes with tuned porosity on the other side, and their incorporation in solid state dye sensitised solar cell (ss-DSSCs), with the aim to improve their photovoltaic efficiency and the long term stability. To best of our knowledge, DSSCs comprising bimodal TiO2 layers and polysiloxane electrolytes have never been reported.The ionic conductivity and tri-iodide diffusion coefficient of the polysiloxane-based poly(ionic) liquids (PILs) were largely improved by adding of ionic liquids (ILs) or ethylene carbonate (EC), achieving ionic conductivities of 10−4 -10−3 Scm−1. The DSSCs fabricated with the optimized electrolytes showed efficiencies up to 6%, with long term stability for 250 days.Bimodal TiO2 films with dual porosity (meso- and macro-porosity) were fabricated by spin-coating, by using soft and hard templating. The dual templated films benefit from increased pore size while maintaining high surface area for dye adsorption. Bimodal films were shown to be more efficient when tested with polymer electrolytes, having comparable efficiencies with liquid electrolyte when in DSSCs, despite lower dye uptake.This thesis brings a significant contribution to the field of DSSCs as efficient and stable solar cells were prepared from newly synthesized polymer electrolytes and bimodal films.

Orientador: Antônio de Pádua Lima Filho / Banca: João Batista Campos Silva / Banca: Alcides Padilha / Resumo: É apresentado um estudo experimental da laminação de tiras fundidas a partir do material semi-sólido obtido na calha de resfriamento que alimenta continuamente um laminador duo. Os cilindros do laminador estão posicionados horizontalmente e podem ser operados na velocidade de 0,25 m/s, 0,47 m/s, 0,73 m/s e 1,07 m/s. A velocidade de 0,25 m/s produziu uma tira de melhor qualidade. Ligas hipoeutéticas Pb/Sn (Pb-30%Sn, Pb-40%Sn, Pb-50%Sn) e próxima ao ponto eutético (Pb-63%Sn), respectivamente, com intervalo de solidificação de 75 °C, 56 °C, 31 °C e 6 °C de acordo com o diagrama de fases, foram utilizadas nos ensaios experimentais para obter tiras semi-sólidas fundidas e tixoconformadas para comparação. As diversas simulações usando as ligas de Pb/Sn têm revelado a importância do intervalo de solidificação e temperatura de vazamento da liga, da velocidade dos cilindros, da temperatura do bocal junto ao cilindro inferior, da superfície de acabamento dos cilindros e da geometria da panela intermediária (tundish), sobre a qualidade do produto final. A liga Pb-30%Sn com alto intervalo de solidificação em comparação com outras ligas testadas, apresentou maior dificuldade para ser tixolaminada. Isso ocorreu, porque as ligas de alto intervalo de solidificação tendem a formar trincas à quente no final da solidificação. Como resultado, uma pasta metálica plástica é difícil de formar. O caminho provável para obter uma tira semi-sólida fundida de boa qualidade neste caso, é aplicar uma inoculação que produz grãos finos antes do vazamento. O controle para a tixolaminação empregando a liga Sn-37%Pb com intervalo de solidificação menor, e elevada fluidez, é mais rigoroso para obter uma tira contínua. Conseqüentemente, foram utilizadas diferentes temperaturas de vazamento (260, 240 e 220 ºC) para controlar a fluidez e obter o tempo de contato... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This is an experimental study of cast strip rolling from semi-solid material employing a cooling slope which continuously feeds a rolling mill. The cylinders of the rolling mill are positioned horizontally and can be operated at speeds of 0.25 m/s, 0.47 m/s, 0.73 m/s and 1.07 m/s. The lower speed of 0,25 m/s produces a strip of better quality. Hypoeutectic Pb/Sn alloys (Pb-30%Sn, Pb-40%Sn, Pb-50%Sn) and near eutectic point alloys (Pb-63%Sn), with solidification intervals of 75°C, 56°C, 31°C and 6°C respectively, according to the phase diagram, were used in experimental tests to obtain cast semi-solid and thixorolled strips for comparison. Simulations highlighted the necessary control parameters required to obtain good quality of the strip. These were: control alloy solidification interval, pouring temperature, roll speeds, ceramic nozzle temperature at the lower roll, quality of the roll surface finishing and tundish geometry. The Pb-30%Sn alloy, which has a much higher solidification interval in comparison with the other alloys tested, was difficult to thixoroll. This is because alloys with a high solidification interval tend to form hot tears at the end of solidification, and prevent a plastic metallic mush from forming. The probable solution to obtaining a semi-solid fused strip of good quality with this material, is to apply an inoculation that produces fine grains just before the pouring. In contrast, the parameter control for thixorolling of the Sn-37%Pb alloy, with lesser solidification interval and elevated fluidity, needed to be rigorous to obtain a continuous strip. Consequently, several pouring temperatures (260, 240 and 220ºC) were used to vary the fluidity and obtain sufficient alloy-inferior cylinder contact time for complete solidification. The strips obtained by the twin and single roll processing, and conventional rolling were characterized... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-12-17T15:01:34Z (GMT). No. of bitstreams: 1 PedroFSF_DISSERT.pdf: 2707475 bytes, checksum: 2a6ef9226a3d6d607615f74305bb9e07 (MD5) Previous issue date: 2014-05-09 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The need for new sources of energy and the concern about the environment have pushed the search for renewable energy sources such as ethanol. The use of lignocellulosic biomass as substrate appears as an important alternative because of the abundance of this raw material and for it does not compete with food production. However, the process still meets difficulties of implementation, including the cost for production of enzymes that degrade cellulose to fermentable sugars. The aim of this study was to evaluate the behavior of the species of cactus pear Opuntia ficus indica and Nopalea cochenillifera, commonly found in northeastern Brazil, as raw materials for the production of: 1) cellulosic ethanol by simultaneous saccharification and fermentation (SSF) process, using two different strains of Saccharomyces cerevisiae (PE-2 and LNF CA-11), and 2) cellulolytic enzymes by semi-solid state fermentation (SSSF) using the filamentous fungus Penicillium chrysogenum. Before alcoholic fermentation process, the material was conditioned and pretreated by three different strategies: alkaline hydrogen peroxide, alkaline using NaOH and acid using H2SO4 followed by alkaline delignification with NaOH. Analysis of composition, crystallinity and enzymatic digestibility were carried out with the material before and after pretreatment. In addition, scanning electron microscopy images were used to compare qualitatively the material and observe the effects of pretreatments. An experimental design 2? with triplicate at the central point was used to evaluate the influence of temperature (30, 40 and 45 ?C) and the initial charge of substrate (3, 4 and 5% cellulose) in the SSF process using the material obtained through the best condition and testing both strains of S. cerevisiae, one of them flocculent (LNF CA-11). For cellulase production, the filamentous fungus P. chrysogenum was tested with N. cochenillifera in the raw condition (without pretreatment) and pretrated hydrothermically, varying the pH of the fermentative medium (3, 5 and 7). The characterization of cactus pear resulted in 31.55% cellulose, 17.12% hemicellulose and 10.25% lignin for N. cochenillifera and 34.86% cellulose, 19.97% hemicellulose and 15.72% lignin for O. ficus indica. It has also been determined, to N. cochenillifera and O. ficus indica, the content of pectin (5.44% and 5.55% of calcium pectate, respectively), extractives (26.90% and 9.69%, respectively) and ashes (5.40% and 5.95%). Pretreatment using alkaline hydrogen peroxide resulted in the best cellulose recovery results (86.16% for N. cochenillifera and 93.59% for O. ficus indica) and delignification (48.79% and 23.84% for N. cochenillifera and O. ficus indica, respectively). This pretreatment was also the only one which did not increase the crystallinity index of the samples, in the case of O. ficus indica. However, when analyzing the enzymatic digestibility of cellulose, alkali pretreatment was the one which showed the best yields and therefore it was chosen for the tests in SSF. The experiments showed higher yield of conversion of cellulose to ethanol by PE-2 strain using the pretreated N. cochenillifera (93.81%) at 40 ?C using 4% initial charge of cellulose. N. cochenillifera gave better yields than O. ficus indica and PE-2 strain showed better performance than CA-11. N. cochenillifera proved to be a substrate that can be used in the SSSF for enzymes production, reaching values of 1.00 U/g of CMCase and 0.85 FPU/g. The pretreatment was not effective to increase the enzymatic activity values / A necessidade de novas fontes de energia e a preocupa??o com o meio-ambiente t?m impulsionado a pesquisa por fontes renov?veis de energia, como o etanol. O uso de biomassa lignocelul?sica como substrato aparece como uma importante alternativa devido ? abund?ncia desta mat?ria-prima e por n?o concorrer com a produ??o de alimentos. Entretanto, o processo ainda encontra dificuldades de implementa??o, entre elas o custo para produ??o das enzimas que degradam a celulose em a??cares fermentesc?veis. O objetivo deste trabalho foi avaliar o comportamento das esp?cies de palma forrageira Opuntia ficus indica (gigante) e Nopalea cochenillifera (mi?da), comumente encontradas na regi?o Nordeste do Brasil, como mat?rias-primas para produ??o de: 1) etanol celul?sico pelo processo de sacarifica??o e fermenta??o simult?neas (SFS) usando duas cepas diferentes de Saccharomyces cerevisiae (PE-2 e LNF CA-11) e 2) enzimas celulol?ticas atrav?s da fermenta??o em estado semiss?lido (FES) usando o fungo filamentoso Penicillium chrysogenum. Antes do processo de fermenta??o alco?lica, o material foi condicionado e pr?-tratado por tr?s diferentes estrat?gias: per?xido de hidrog?nio alcalino, alcalino usando NaOH e ?cido usando H2SO4 seguido de deslignifica??o alcalina com NaOH. An?lises de composi??o, cristalinidade e digestibilidade enzim?tica foram feitas com o material antes e depois do pr?-tratamento. Adicionalmente, imagens de microscopia eletr?nica de varredura foram usadas para comparar qualitativamente o material e observar os efeitos dos pr?-tratamentos. Um planejamento fatorial 2? com triplicata no ponto central foi utilizado para avaliar a influ?ncia da temperatura (30, 40 e 45 ?C) e da carga inicial de substrato (3, 4 e 5% de celulose) no processo SFS, usando o material obtido nas melhores condi??es de pr?-tratamento e testando duas cepas de S. cerevisiae, sendo uma delas floculante (LNF CA-11). Para a produ??o de celulase, o fungo filamentoso P. chrysogenum foi testado com a esp?cie de palma N. cochenillifera no estado in-natura (sem pr?-tratamento) e submetida a um pr?-tratamento hidrot?rmico, variando-se o pH do meio fermentativo (3, 5 e 7). A caracteriza??o das palmas forrageiras resultou em 31,55% de celulose, 17,12% de hemicelulose e 10,25% de lignina para a esp?cie N. cochenillifera e 34,86% de celulose, 19,97% de hemicelulose e 15,72% de lignina para a esp?cie O. ficus indica. Analisou-se ainda, para as palmas mi?da e gigante, o teor de pectina (5,44% e 5,55% de pectato de c?lcio, respectivamente), extrativos (26,90% e 9,69%, respectivamente) e cinzas (5,40% e 5,95%). O pr?-tratamento usando per?xido de hidrog?nio alcalino apresentou os melhores resultados de recupera??o de celulose (86,16% para a palma mi?da e 93,59% para a palma gigante) e de deslignifica??o (48,79% e 23,84% para as palmas mi?da e gigante, respectivamente). Este pr?-tratamento foi tamb?m o ?nico a n?o elevar o ?ndice de cristalinidade das amostras, no caso da palma gigante. Entretanto, quando analisada a digestibilidade enzim?tica da celulose, o pr?-tratamento alcalino foi o que proporcionou os melhores rendimentos e, portanto, este foi o escolhido para os testes de SFS. Os experimentos demonstraram maior rendimento da convers?o de celulose em etanol pela cepa PE-2 usando a palma mi?da pr?-tratada (93,81%) a 40 ?C e usando 4% de carga inicial de celulose. A palma mi?da demonstrou melhores rendimentos que a gigante e a cepa PE-2 resultou melhor desempenho que a CA-11. A palma mi?da se mostrou um substrato poss?vel de ser usado na FES para produ??o de enzimas, alcan?ando valores de 1,00 U/g de CMCase e 0,85 FPU/g. O pr?-tratamento n?o se mostrou eficaz para aumentar os valores de atividade enzim?tica

The mechanical properties achieved with high performance wrought aluminium alloys are superior to cast aluminum alloys. To obtain an intricate shaped component, wrought alloys are commonly subjected to forging followed by subsequent machining operation in the automobile industry. As machining of such high strength wrought aluminium alloys adds to cost, productivity gets affected. Shortening the process by near net shaped casting would tremendously enhance productivity. However, casting of such alloys frequently encounter hot tear defect. Therefore, circumventing hot tear to successfully die cast near net shaped wrought alloy components is industrially relevant. A recent advanced casting process, namely ‘Semisolid Die casting’, is proposed as a likely solution. Hot tearing originates due to lack of liquid flow in the inter-dendritic region. To reduce hot tear susceptibility, fine and non-dendritic grain structure is targeted, amenable for processing by semisolid route. For semisolid processing an adequate freezing range for processing is required. Accordingly A6061 wrought alloy whose composition is tuned with higher silicon and magnesium content within the grade limits, is chosen for the study. With the objective of obtaining fine and non-dendritic microstructured billets, electromagnetic stirring (EMS) and cooling slope (CS) methods are employed. On conducting a parametric study with EMS, a finest possible primary α-Al grain size of about 70 μm is obtained at low stirring time at stirring current levels of 175 A and 350 A, with the addition of grain refiner. CS, on the other hand, rendered a grain of 60 μm at a slope length of 300 mm at a slope angle of 45° with grain refiner addition. Of the two methods, CS billets are chosen for subsequent induction heating. A 3-step induction heating cycle has been devised to attain a temperature of 641°C in the billet on the basis of factors including coherency point, viscosity of the slurry and solid fraction sensitivity with temperature. The billet microstructure is found to be homogenous throughout after quenching in water. The characterization of phase along primary α-Al grain boundary and its composition analysis is done by SEM and EPMA respectively, after billet casting as well as induction heating. In addition, the bulk hardness is determined in BHN. The induction heated billets are semisolid die cast to produce an engine connecting rod used in automobiles. The microstructure is characterized at various locations, and is found to consist of smooth α-Al grains in a background matrix of fine grains formed due to secondary solidification. The component hardness is found to be 66 BHN comparable with A6061 alloy under T4 heat treated condition. X-ray radiography does not confirm presence of surface hot tear, which is the normal defect associated with casting of wrought aluminium alloys. No defects are observed along the constant cross-sectional area of the connecting rod, suggesting that the processing could be suitable for semisolid extrusion.

Gradientes térmicos induzidos no interior de componentes sujeitos a variações de temperatura durante o período de funcionamento podem provocar a ocorrência de tensões e deformações internas. A repetição destes ciclos térmicos pode causar a nucleação e a propagação de trincas por um processo denominado fadiga termomecânica. Este trabalho apresenta um estudo sobre o comportamento da liga de alumínio A356-T6, processada nas condições fundida e tixoextrudada, sob fadiga isotérmica e termomecânica. Foram realizados ensaios de fadiga de baixo ciclo isotérmica para as temperaturas de 120 e 280°C, e ensaios de fadiga termomecânica em-fase e fora-de-fase para a faixa de temperatura de 120 a 280°C. O material tixoextrudado apresentou melhor desempenho em fadiga nas condições isotérmica e anisotérmica (termomecânica) devido a uma microestrutura globular com menor nível de porosidade. / Thermal gradients induced in components during service under temperature changes can cause internal stresses and strains. This cyclic thermal behavior can cause crack nucleation and propagation under a process denominated thermomechanical fatigue. Permanent mold casting and tixoextruded A356-T6 aluminum alloy behavior under isothermal and thermomechanical fatigue was study in this work. Isothermal low cycle fatigue tests were performed in temperatures of 120 and 280°C. In-phase and out-of-phase thermomechanical fatigue tests were carried out in temperature range from 120 to 280°C. The tixoextruded material presented better isothermal and thermomechanical fatigue performance due to a globular microstructure and lower porosity level.

No description available.

ヘテロ構造組織を有する鉄・非鉄金属の組織形態に注目して,微視的構造やその挙動が巨視的現象(変形特性,成形性)として発現するメカニズムを解明することを目的とした.鉄系金属ではDual Phase型高張力鋼のスプリングバック現象のひずみ速度依存性,非鉄系金属では半凝固鋳造法と強ひずみ加工を組み合わせた亜共晶アルミニウム合金の衝撃後方押出し成形性に注目した.これらの検討によりいずれの試料においても,結晶粒界よりもスケールの大きいヘテロ構造に由来した変形機構が支配的であることが明らかになった. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University