京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20336号 / 工博第4273号 / 新制||工||1662(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 松原 英一郎, 教授 乾 晴行 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

<p>Pack-rust corrosion is a type of corrosion that affects steel built-up members especially old  bridges. It is a localized corrosion that happens in the crevice between two mating surfaces. Pack-rust corrosion does not only cause section loss like other types of corrosions, but also induces local distortion in the structural members that are not the intention of the original designs. This corrosion can change the behavior of the connection fixity and could also cause instability in the overall  built-up members. The size of distortion and section loss were observed to behave linearly between  the free edge and the first line of fasteners. As the distance is moving toward the free edge, the  distortion in the members and section loss in the base material were observed to be maximum. Another important observation was that pack-rust corrosion does not grow beyond the fastener at the fastener’s line. </p> <p>The literature revealed that there are no comprehensive experimental and analytical studies focused on the behavior and effect of pack-rust corrosion on the overall performance of built-up members and connections in compression. Therefore, this research studies the effects of pack-rust corrosion on the capacity of built-up compression members including but not limited to stiffness, yield strength, maximum capacity, and change in fastener force under applied load. This research was studied by performing large-scale experimental testing of flexural members with simulated pack rust. Pack-rust distortion was simulated by placing washers in the crevice between two plates and then the two plates were drawn together using high-strength fasteners. There were also members with real pack-rust corrosion damage from bridge components that used to be in service, and were tested in axial compression tests. </p> <p>The experimental results were compared with hand calculation using conventional design  equations. Finite element analysis was also studied to compare with the experimental results in  order to calibrate future models, but it is not presented in this report. The findings of the  experimental results of all the specimens show that pack-rust corrosion affects yield strength and  maximum capacity of the member and minimally affects the member’s stiffness. Maximum load  of the member affected by pack-rust corrosion can still be estimated conservatively using the  conventional design equations with some modifications. There was no indication of significant  increase in fastener force under applied load, so the likelihood of fastener failing in tension was  very small as observed from this study.   </p>

During the last four decades, fiber reinforced concrete has been increasingly used in structural applications. It is generally accepted that addition of steel fibers significantly increases tensile toughness and ductility, also slightly enhances the compressive strength. Although several studies have reported previously the favorable attributes of steel fiber reinforced concrete (SFRC), little general data is related to performance modeling. There are studies on the effect of fibers on compression, tension and shear behavior of concrete. As models proposed so far can, at best, describe only a few aspect of SFRC with a given type and amount of fibers, establishing simple and accurate generalized equations to describe the behavior of SFRC in tension, compression and shear that take into account the fiber type and content is essential. Therefore, a comprehensive experimental research on SFRC is conducted in University of Canterbury to develop generalized equations to represent the characteristics of SFRC. In this research, standard material tests of SFRC are carried out in tension, compression and shear to enable the parametric characterization and modeling of SFRC to be conducted. The tests are conducted using two different propriety fiber types (NovotexTM and DramixTM) with volumetric ratios ranging from 0 to 2 percent of the Novotex fibers and with 1 percent Dramix fibers. Compression tests are conducted on small and large cylinders. For characterization of tensile behavior, several different test methods are used including: direct tension of SFRC alone; SFRC with tension applied to an embedded longitudinal rebar; and flexural bending test. Similarly direct shear tests are conducted to investigate the additional shear resistance contributed by steel fibers. Variations in the results of different specimens are reconciled through normalization of stress and strain parameters. Based on the experimental results, empirical relations are derived for modeling and analysis of SFRC.

No description available.

Ce travail de thèse vise à améliorer la compréhension des phénomènes physiques se produisant durant le pressage en continu des graines oléagineuses et à développer un modèle phénoménologique décrivant le comportement mécanique de la matière au cours de sa compression le long de la vis. Les expérimentations ont été réalisées sur des graines de colza, en utilisant un pilote de presse à vis instrumenté (Reinartz, Allemagne). Deux arrangements de vis différents ont été étudiés et comparés, de manière à observer l’influence de la géométrie sur les performances opératoires, le développement des contraintes à l’intérieur de la cage et les propriétés mécaniques du gâteau de pressage. L’instrumentation de la presse a permis de générer des données précises de débits d’huile et de gâteau, capacité de traitement, rendement d’extraction et consommation d’énergie spécifique, pour des vitesses de rotation de la vis comprises entre 0 et 18,2 tr/min. Des profils de pression, teneur en huile et vitesse de déplacement ont également été déterminés pour les deux arrangements de vis, pour caractériser le fonctionnement de la presse. Ces données ont permis d’identifier une alternance de zones de compression et de transport le long de la vis, avec une présence éventuelle de phénomènes de reflux. Une représentation simplifiée a été proposée, pour décrire le pressage continu comme une succession de d’étapes de pressage discontinu. En se basant sur la théorie de filtration/consolidation, le coefficient de consolidation, le module de compressibilité et la résistance spécifique du gâteau de pressage ont étés calculés pour chaque zone de compression. Les propriétés mécaniques du gâteau de pressage ont finalement été utilisées pour développer une relation semi-empirique permettant de prédire le débit d’huile et le rendement d’extraction de la presse. Les résultats expérimentaux correspondent aux données estimées avec une précision satisfaisante. / This work was devoted to better understand the physical phenomena occurring during oilseeds expression in continuous screw presses and to develop a phenomenological model describing the compression behavior of the press cake along the screw. Experiments were conducted on canola seeds, using an instrumented pilot screw press (Reinartz, Germany). Two different screw arrangements were studied and compared in order to observe the influence of the geometry on the operating performances, the constraints development in the barrel and the press cake mechanical properties. Press monitoring provided accurate data about oil and cake flowrates, treatment capacity, extraction yield and specific energy consumption, for screw rotation speeds ranging between 0 and 18.2rpm. Pressure, deoiling and displacement velocity profiles were also determined for both arrangements to characterize the press operation. These data allowed to identify the alternation of compression and transport sections along the screw, possibly supplemented by oil reflux. A simplified representation was proposed, describing continuous pressing as a succession of multiple batch pressing steps. Based on the filtration/consolidation theory, the consolidation coefficient, compressibility modulus and press cake specific resistance were calculated in each compression sections. The press cake mechanical properties were finally used to develop a semi-empirical relation predicting the press oil flowrate and extraction yield. Experimental results fitted the estimated data with satisfactory accuracy.