The Tohoku earthquake (March 11, 2011) has made us pay more attention to tsunami disaster than before. One of the most important things in the tsunami is an immediate evacuation from it. While we should conduct a tsunami evacuation drill in order to enhance our decision, it is impossible for us to experience a tsunami directly. For training as many people as possible, especially children and old persons, we have been developing a portable tsunami virtual reality (VR) system using three key technologies; the head-mounted display (HMD), the laptop computer and the tsunami CFD simulation. We correctly reproduce the tsunami behavior using a particle(SPH)-based CFD method. In this study, we confirm the validity of the car’s movement in the analysis by comparing it with the theoretical value of the drifting limit, and applied it to the tsunami simulation. The simulation results are virtually visualized in three dimensions by the HMD.

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In recent years, ocean energy attracts people’s attention as one of renewable energy. A lot of the power generation using ocean energy is delayed in development,especially in Japan due to the influence of typhoons. Therefore, we have been developing new compact and low-cost, but flexible wave power generator which can work under the motions of multi-degree of freedom. In this study, we improve the power generation unit in the device to efficiently generate electricity. In order to optimize the unit, it is indispensable to elucidate the electromagnetic field mechanism such as magnets and coils, so we perform electromagnetic field analysis and compare the experiment results with the analysis results.

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We have been developing a compact and highly efficient wave power generator, which also has a surface traveling capability in order to move back to the home station and to discharge the stored electricity. In this study, we presented a new surface traveling mechanism of the generator for the purpose of electric machine recovery, improvement of power generation efficiency and prevention of failure. We numerically evaluated the equipment dimensions and magnet weight required for the generator to rotate and to move on water. In addition, we computed the magnetic field characteristics in the equipment and the behavior of the magnets using electromagnetic field analysis code, and compared the results with the experiments.

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For the purpose to design Vortex generator（VG) for a wind turbine blade by numerical simulation, the prediction accuracy of the fluid analysis soft, OpenFOAM which is open source software was examined. The subject is the airfoil widely used in wind turbine. At the angle of attack which causes separation on blade surface, the change of blade surface pressure coefficient depending on the VG was compared with the existing experimental results. For the analysis, “simpleFoam” which is the three dimensional, steady-state, incompressible flow simulation module based on the SIMPLE method was used, and “k-ω SST model” was selected as a turbulence model. For generation of computational grid, blockMesh which is the multiblock grid generation soft of OpenFOAM and snappyHexMesh which is grid generation soft adaptable to complex shape were used. The height of VG was designed to be same as the boundary layer thickness. The parameter of near wall boundary was set in this analysis so that about 10 grid points enter in VG height direction. As the result of simulation, it was shown that the vortex of different rotation direction which is characteristic of Counterrotation configuration was generated from VG and the pressure rise due to separation on suction surface was suppressed by the attachment of VG and it turned out that VG effect was qualitatively predictable by using OpenFOAM.

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In this presentation, we report the results of applying the extended finite element method to magnetostatic analysis with complex shape cracks. In this method, the enrichment function, which represents the local features of the solution, is folded by conformal mapping. As a result, the crack is changed from straight style to kinked style.

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For enhancing design-by-analysis optimization of various microfluidic devices, a lattice Boltzmann method (LBM) is preliminarily evaluated in three-dimensional numerical simulation of microscopic liquid flows. The LBM is first applied to a single-phase fluid flow through a porous media with porosity of 0.8 which consists of cubic solid bodies located in random arrangement. The numerical results of fiction factor agree well with the Ergun and Blake-Kozeny empirical equations. In the second application to an immiscible liquid-liquid two-phase flow in a flow-focusing microchannel device, it is confirmed that dispersed-phase droplet formation takes place in agreement with available experimental data. The above benchmark tests demonstrate that the LBM is applicable to actual microfluidic problems.

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[in Japanese]

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The isochronal failure behavior of poly(methyl methacrylate)(PMMA) was investigated under pure shear and simple tension in air at high temperature. The shear flow was observed with diffuse zone under both stress states, and confirmed to occur obeying the modified von Mises criterion. On the other hand, craze formation occurred only under simple tension at lower stress than shear flow, i.e. no crazing was observed under pure shear. A pre-shear flow with very vague deformed zone was found before clear shear band formation under both stress states. No crazing under pure shear was supposed to be due to this pre-shear flow, although a criterion of Kawagoe et al. has predicted craze initiation under pure shear.

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A buckling evaluation method without buckling tests or simulations for plate structures with corner dimension was proposed. The buckling strength is given as the product of Euler’s buckling force and buckling coefficient. In the previous study, a buckling coefficient for flat plates was derived, and an evaluation method for that was proposed. In this study, we extended the buckling coefficient for the flat plates to that for plates with corner dimensions at the both ends. Next, buckling analyses were executed to solve buckling forces for the plates under the conditions of various corner dimensions, and then an effective buckling length factor was derived to predict the buckling coefficients and the buckling forces. By comparing the buckling forces between the buckling analyses and the proposed method, it was found that buckling forces of the plates can be predicted within an error of 2.48 %, and the established method is available for buckling evaluation for the plate structures with the corner dimension.

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Making a mandibular CAD model was difficult because of the limit of computer performance. But recently the progress of computer performance is remarkable. In this study, entire mandibular CAD model was made using two softwares. First, the mandibular STL (Standard Triangulated Language) model was made using the three-dimensional image analysis software. It was extracted from CT image. Second, Mandibular CAD model was made using reverse engineering software. The dental implant model was made on the basis of products made in Japan. It was placed in first premolar and second premolar. The vertical load (100N) was applied on the dental implant and the stress distribution was calculated using FEM. The heterogeneity stress was generated in the surface of the cortical bone around the body of the implant. Uneven surfaces were made in process of making mandibular STL model. The stress distribution was affected by the place of dental implants and the surface forms of the cortical bone.

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To consider measures for protecting severe accident, the evaluation of equipment damage caused by tsunami debris in a nuclear power plant is necessary. The purpose of this study is to establish a method to evaluate the condition of the equipment hit by tsunami debris. In the condition evaluation, it is necessary to set the impact force appropriately. In this study, we focused on FEMA’s formula, which is one of the evaluation formulas to estimate impact forces of tsunami debris. Added mass and velocity necessary for the calculation in the formula was investigated by impact experiment in the tank with water. The increase of the force due to the added mass was not observed in the stationary water, rather the decrease of the force due to the influence of water on the impacted object. The decrease of the velocity was confirmed when the flat surface impacted against each other with water.

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Hook bolts are used to fix railroad sleeper and bridge girders in a railroad bridge. The type of hook bolt is roughly divided into a J-shaped one and a L-shaped one (hereinafter referred to as a L-shaped hook bolt). Research on fastening characteristics of J-shaped hook bolts has been researched by the authors, but L-shaped hook bolts are scarcely investigated, whose design is mainly dependent on experience. Therefore, in this study, based on the beam theory model, experiments and Finite Element Method (FEM), we investigated the influence of the arm length of the L-shaped hook bolt on the axial force and the torque coefficient, and clarify the fastening characteristics.

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Morphology and material organization of living things in nature are extremely complicated, and their creation mechanism is not well understood. However, as it has evolved over the years, it seems to be the result of optimization to the natural world. Therefore, observing the structure of living organisms and clarifying their mechanical properties seem to be important for mechanical design. For this reason, we focus on trees that are familiar creatures in this study. Tsushima and others have made it clear that trees have a gradient function that increases the Young’s modulus as they go from the root to the tip. Such characteristics can be considered as a factor of flexibility of trees. Therefore, in this study, after choosing Ginkgo as a target material, we will determine the Young’s modulus distribution using both cantilever deflection measurement test and inverse analysis method with axially functionally graded material and taper. Next, a large deflection experiment is carried out by the same cantilever beam, and its deformation characteristics are clarified by comparing with the theoretical and the analysis results by Finite Element Method(FEM).

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The focus of this study is to clarify effects of interface edge condition on the bonding strength of ceramic to metal joint. The interface edge condition was characterized by edge angle defined as a configuration angle between the free surfaces and the interface in both sides of the ceramic and metal. As the edge angle of Si₃N₄ is set at φ₁=60°, the edge angle of Ni is set over 30°≤φ₂≤180°. Experimental results showed that increasing the edge angle improves the bonding strength in range over 60°≤φ₂≤105°since it may decrease the residual stress near the edge of the interface. The maximum tensile bonding strength was observed at the edge angle of φ₂=135°. A dependence of changing ceramics edge shape on the improvement effect by changing metal edge shape was considered by comparing the experimental results with our previous data.

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This paper provides effects of removal amount of surface induced by the indentation crack on the fracture toughness for the single crystal silicon wafer. Removing the residual stress should be required on CSF method for evaluating the fracture toughness of brittle materials after indentation crack induced. It attempts to clarify the effects by using ion shower which can control the removal amount with micro meter order. Fracture toughness of cleavage plane of single crystal silicon was evaluated by CFS method. Effects of removal amount and crack shapes on the fracture toughness were evaluated by using ion shower. The validity of the fracture toughness value was considered by compairing both results of CSF and IF methods. An appropriate amount removed by usage of the ion shower was proposed for evaluating the fracture toughness.

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This study provides an estimation method of surface crack depth of electric conductive Zirconia induced by wire EDM based on the fracture dynamics. The fracture dynamics model was used for this analysis. The crack depth was evaluated experimentally by two different methods. One of them was derived from ground removal amount of the W-EDMed surfaces that can recover the fracture strength. The other was derived from the rest of the crack depth and ground amount of the wire EDMed surface. These estimated values were compared each other to clarify the surface crack depth induced by wire EDM. The surface crack depth was predicted by considering experimental results and the residual stress on the surface measured by X-ray analysis.

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Small-scale hydroelectric power generation has recently attracted considerable attention. We have investigated an undershot cross-flow water turbine with a very low head suitable for application to open channels. Because we removed the turbine casing and guide vane, free surface flow patterns of the undershot cross-flow water turbines are very complex. We have researched free surface flow patterns around the turbines and how the blade’s shape influenced the turbine’s performance using both experiment and numerical analysis. In results, the output power and the turbine efficiency of Straight Blades runner were greater than those of the Curved Blades runner regardless of the rotation speed. However, we didn’t know factor the performance difference Straight Blades runner and Curved Blades runner. To resolve this issue, we built the method to estimate the torque of kinds of flow and the torque of physical force component. In this research, the method applied to an undershot cross-flow water turbine with straight blades. So, we examined factor the performance difference Straight Blades runner and Curved Blades runner.

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A gravitation vortex type water turbine is a water turbine which generates power by the gravitational vortex. Although this water turbine can be generated by a low head and a smallness flow, the flow field is a complicated thing which has a free surface. Therefore, effect of number of blades on the performance and flow field of this water turbine is not clarified. In this study, the performance and flow field in number of blades changed were investigated by experiments and free surface flow analyses. As the results, the following facts were clarified. The turbine output, the effective head and the turbine efficiency of the experimental value and the analysis value were comparatively satisfactorily in agreement at the time of number of blades changed. Since the angular momentum in the tip side at the blade outlet increased negatively as number of blades increased, it is thought that the turbine output increased.

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In recent years, miniaturization and densification of electronic devices have progressed, and the space where fans are mounted becomes a narrow environment, and it is required to establish design guidelines for fans assuming use in narrow spaces. Research on flow field and performance of axial flow fans in narrow spaces has been conducted, and many findings have been reported. However, although much research has been done on multi-blade fans, there have been few researches on thin multi-blade fans capable of saving space in the axial direction, much less about flow fields and performance in narrow spaces. Therefore, in this research, as a first step toward establishment of design guidelines for thin multi-blade fans in a narrow space, in order to reproduce a narrow space, a disk-shaped obstacle was installed on the inlet side of the multi-blade fan, and we investigated the influence on the flow field and performance by changing the position of its axial direction by experiment and numerical analysis. As a result, the performance becomes low as the axial distance of an obstacle becomes small. At the low flow rate, the circumferential component of the absolute velocity of the blade inlet increased with the obstacle, and it became clear that the theoretical total pressure coefficient becomes low.

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The purpose of this study is to clarify the performance characteristics and internal flow of dental air turbine handpiece. Therefore, the performance test by the actual machine and the numerical analysis by the handpiece model were carried out. The calculated values and the experimental values were compared for the torque and turbine output, and it was confirmed that the two agree well. In the numerical analysis, it was confirmed that the fluid loss in the turbine section was large. Focusing on the flow in the nozzle and the rotor, investigating the internal flow for each rotational speed and blade phase angle revealed the mechanism of torque generation and factors of torque fluctuation.

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In the design study of an advanced loop-type sodium-cooled fast reactor in Japan Atomic Energy Agency, a specific fuel assembly named FAIDUS (Fuel Assembly with Inner Duct Structure) has been adopted as one of the measures to enhance safety of the reactor in the core disruptive accident (CDA). Thermal-hydraulics evaluations in FAIDUS under various operation conditions including the CDA are required to confirm its design feasibility. It is demanded to evaluate thermal-hydraulics in a FAIDUS which has complicated flow path formed by wire-wrapped fuel pins, wrapper tube, and inner duct, by using numerical simulations. Therefore, numerical simulations by using detail thermal-hydraulics analysis program for a sodium-cooled fast reactor (SPIRAL) developed in JAEA are conducted to analyze the thermal-hydraulics in the FAIDUS. Through the numerical simulation, specific temperature distribution in the FAIDUS due to existence of the inner duct was indicated and applicability of SPIRAL to the FAIDUS is confirmed.

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This paper deals with the phenomenological study on the liquid droplet formation around nuclear fuel under high pressure conditions. The thermal hydraulic safety limit of nuclear fuel is characterized by the liquid film depletion with high steam flow, and the liquid droplet is considered to play an important role on it. It was demonstrated that the initial droplet would be produced due to the instability between liquid film and steam flow, and this trend would be shown within the pressure range from atmospheric to 1.0 MPa.

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Static gravimetric method with flying start-and-finish is widely used for calibration of large and medium liquid flow for its advantage of maintaining continuous flow through the flowmeter. However one needs to take careful measures in implementing this method in low flow systems to obtain good accuracy. At NMIJ/AIST, we adopted this calibration method using a pair of high speed switching valves as diverter for flow range below 1 L/h. This paper describes the design features and characteristics of the gravimetric system, and also discusses the timing error of the diverting valves evaluated according to ISO4185.

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Supercritical dimethyl ether spray was observed using a high-speed video camera under the ambient temperature and pressure conditions of typical turbocharged engines in an optically accessible constant volume vessel. Parallel shadow graph and diffuse light shadow graph techniques were employed to visualize the liquid and vapor phase behavior separately. The results show that there are not significant differences in spray shape and vapor penetration length between supercritical and subcritical spray, although the liquid length of supercritical spray is shorter and the ignition delay is slightly earlier than that of subcritical spray.

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To investigate the effect of pressure ratio of the injection pressure to the ambient pressure on the mass flow of DME spray, the injection rate with the change of the ambient pressure was measured in a constant volume vessel. The injection rate was determined by the spray impact method; the measurement of the impact force time-histories using a pressure transducer. The injection speed from the nozzle outlet was also determined to understand whether the choked flow occurred or not.

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In this study, ignition characteristics of dual fuel HCCI were investigated using a single cylinder HCCI engine. Fuels having different low temperature oxidation (LTO) reactivity, methane, propane, isobutane and n-butane, were used as a secondary fuel, and they were added to n-heptane/air mixture. Methane and propane having no LTO mechanism, isobutene having a weak LTO, and n-butane having the highest reactivity among the secondary fuels used in this study. As a result, it was verified that propane retarded the ignition timing more than methane when they were coexisted with n-heptane, although propane has lower octane number than that of methane. Based on chemical kinetic analysis, this is because propane has higher reactivity with OH than methane. Although coexisting alkanes retard LTO, alkanes with LTO mechanism decreases thermal ignition preparation process. The chemical kinetics analysis suggests that higher H2O2 mole fraction at the end of LTO advances the ignition timing.

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We focused on a homogeneous charge compression ignition（HCCI）engine. HCCI engine is high efficiency and clean combustion. But it has a problem that restraint of steep combustion in the high load and control of the combustion phasing are difficult. In this study, we studied characteristic of the combustion in supercharged HCCI engine with each two kinds of blended fuels, DME/Methane, by adding H₂O. As a result, the addition of H₂O is 3 atom molecules has an effect on the temperature rise is slow by decreasing in specific heat ratio. In addition, it is thought that it is slow, and decrease in evaporation heat and increase thermal capacity may influence an effect. And, by the addition of H₂O, main combustion from LTR which is firing delay period gets longer.

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This study investigated the effect of ignition timing on knocking in an SI engine. Autoignition and abnormal combustion behavior were examined by using light absorption spectroscopy and in cylinder flame visualization techniques. The result showed that the knocking intensity under the same autoignition timing was declined by advancing ignition timing.

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The thermo-physical property of Myristic Acid, Lauric Acid and Capric Acid which are the phase change latent heat storage materials was elucidated in order to consider the temperature dependency. The values of thermo-physical properties such as density, viscosity and the freezing temperatures were measured experimentally.

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A single stage phase change latent thermal storage heat exchange system which is useful in an ambient temperature range were experimentally investigated towards the construction of future multistage system effective in energy saving. We focused on lauric acid which is a kind of fatty acid as a thermal storage medium in the present study. The fatty acid has little influence of supercooling, is easy-to-use, and is one of phase change latent heat storage materials harmless to human body. The heat transport mechanism which accompanies a melting process and a solidification process was analyzed using an appropriate visualization.

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This study focuses on waste heat energy, and is also aimed at developing a high performance heat exchanger. As one of the methods, we developed spray type heat exchanger and liquid film heat exchanger to increase thermal contact area or use positively utilization of phase change heat transfer. At the same time, we evaluated several characteristics of the heat exchanger throughout a series of visualization and heat transfer experiment.

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In the microchannel, the flow pattern of the fluid is different from that in macro scale. In this study, we investigated the flow characteristics of liquid - liquid slug flow and gas - liquid slug flow in a microchannel. As a result of measuring the length of the slug, it was found that the flow characteristics are different between liquid - liquid slug flow and gas - liquid slug flow. In addition, the slug length of the gas - liquid slug flow was better than that of the experimental formula.

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The existing air bubbles are used for engineering including promotion of the heat transfer and the equalization of liquid components in a liquid for the purpose of varying. Particularly, a lot of studies of the single air bubble which became basic of air bubbles dynamics were performed. However, it is necessary to understand the formation of plural bubbles because the engineering often treats it. Therefore this study installed twin nozzle in an inviscid liquid and generated air bubbles by sending air on a constant flow rate condition in the nozzle. We measured a nozzle exit and an air chamber internal pressure in each flow rate using 12 kinds of nozzles which were different from nozzle diameter and nozzle spacing. In addition we photographed the state of bubble departure of nozzle with a high speed camera for some conditions. As a result, this study could pay off the bubbles frequency using air bubbles Reynolds number. And it is related to the change of the air bubbles volume. In addition, it was revealed that the transition flow rate that the formation of bubbles changed existed.

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There is the geyser which water in the underground bedrock layer is warmed by terrestrial heat, and spouts out with heated water and water vapor from the surface of the earth in the natural world. The steady boiling spring is defined when it becomes the high temperature at constant speed without steam being disturbed in structure under the ground. The geyser is defined when there is the cavity where steam can collect in the middle of a crack to continue to the surface of the earth. The steam layer is generated in the place where the geyser varies in the diameter ratio, and the pressure in the gap decreases because steam is pushed up. However, the clear difference between spouting of the geyser and steady boiling spring is not reported. This study is a purpose in clarifying difference of the geyser and the steady boiling spring. It was revealed that geyser spouting period is long than a steady boiling spring.

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Recently years, Mg-alloys have attracted for weight reduction of transportation equipment. To achieve this, bonding technology development is indispensable so we are trying to apply Ultrasonic Welding Method for Mg-alloys. Ultrasonic Welding Method is more efficient bonding method because it consumes less power than Resistance Spot Welding Method and has shorter bonding time. In this research, to elucidate the Ultrasonic Welding mechanism in Mg-alloys, the welding energy was systematically changed in the initial welding process, and measured the change of crystal grain and the distribution of welding region. As a result, the crystal grains on the welding interface at 100J to 500J were observed. Relation was measured between the welding energy and the weld strength.

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The peening treatment is a surface treatment technique that imparts compressive residual stress to the material surface to improve its mechanical properties and corrosion resistance. In order to clarify the difference in surface reforming characteristics by the peening method, microstructure observation was carried out on a shot-peened and laser-peened austenitic stainless steel AISI316 using a transmission electron microscope (JEM-2010). As a result, crystal grain size of several nm to 100 nm were observed on the outermost surface of the shot peened material. In addition, a region where only crystal grain size of 100 nm or more existed depending on the location was observed, and it became clear that the crystal grain size distribution had no uniformity. Furthermore, it was confirmed that the martensite phase also exists in the region under the outermost surface. On the other hand, it was revealed that twin crystals of several nm width were present inside the laser peened material.

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Servo press device developed at 18 years ago has been promoting development of peripheral element technology mainly for higher functionality of processing. However, studies from the view point of academic theories are not sufficient because industrial interests are always given priority as social and economic activities. Therefore, in this study, simple upsetting experiments are conducted on the cold forging by controlling the processing conditions (speed / slide motion) with Stainless, Aluminum and Titanium using a servo press. As a result, It is confirmed that the material properties are affected by the controlling speeds and motions. Especially strain rate dependency and the effect of repeated processing were confirmed in the work hardening of Titanium. Also it is considered that structure of crystals and anisotropy influence the work hardening of Titanium by controlling the processing conditions (slide motion). Residual stress is generated in the soft layer of Titanium due to anisotropy and work hardening is reduced.

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Strain Age hardening has an anisotropy in mechanical property, the stress-strain curve of specimen along the pre-strained direction shows discontinuous yielding behavior while orthogonal one shows continuous yielding. The residual stress caused by inhomogeneous deformation is pointed out as a cause of strain age hardening anisotropy, however detailed mechanism has not been clarified. In this study, we focused on heterogeneous deformation and evaluated the heterogeneous deformation behavior of crystal grains by KAM (Kernel Average Misorientation) and GROD (Grain Reference Orientation Deviation ) obtained by EBSP (Electron Backscatter Diffraction Pattern) analysis. As a result, KAM average value was lower in the orthogonal direction material and ,KAM in the crystal grain was also lower. GROD of the orthogonal direction material showed a lower value (0 ° to 2 °). It was suggested that the behavior of grains shown by these KAM and GROD analysis is affected by strain loading path, resulted in inhomogeneous deformation behavior of crystal grains.

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The effect of the thermal insulation coat on the mold filling for a thin wall aluminum alloy casting in the expendable pattern casting process was investigated experimentally and theoretically. Thin wall aluminum alloy plates were cast by the EPC process using the thermal insulation coat. The fluidity length and melt velocity were measured. Even when the thermal insulation coat was used, the fluidity length of the melt did not increase so much. The fluidity lengths were predicted by using measurement values of the melt velocity. The predicted values were in approximately agreement with experimental values.

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This paper is described about the study on Finite Element Method (FEM) analysis of thin steel sheet bending. Thin steel sheet bending is used as hemming process in automobile industry. Hemming process is one of the thin metal plate bending process for joining the outer panel to the inner panel. Recently the required accuracy is increasing. Hemming process is a simple plastic forming process, however some defects often are occurred such as creepage, growing, warp, recoil and so on. Some studies on hemming process, however these occurring mechanism are not clarified yet. Moreover, selecting hemming process conditions takes cost and time. Therefore, in order to solve these problems, hemming process is reproduced in FEM analysis. For accuracy FEM analysis, it is necessary to give a material properties value correctly. Tensile test and friction test were operated to obtain the flow stress and friction coefficient in preliminary experiment for accuracy FEM analysis. Therefore, in this research the material properties of a specimen are acquired, the metal thin sheet bending that based on the acquired data and FEM analysis of processing are conducted, moreover the experiment and analysis are compared and considered from a load-stroke diagram. Both tendency was good agreement. From this result, coincidence of load-stroke diagram of an experiment and analysis was obtained and it was able to say that it was useful in the FEM analysis of this experiment.

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This paper describes a finite element method (FEM) analysis for cold burring process of large diameter SUS304 pipe. The large diameter pipes such as Φ216.3 mm are used for a plant as a flow channel of gas and liquid. A burring process of pipe is generally for forming the branch. The burring process is achieved by drawing of die from prepared hole. And the branch pipe is welded to the formed pipe. This process has some problem. One is the forming limit of pipe, and the other is needed to machining the end surface to be welded. Each problems are depend on the prepared hole shape, thus the optimum prepared hole shape is required. In this study, FEM analysis was operated to estimate the optimum prepared hole shape. Prepared hole has two dimensions because of ellipse. At first, the length of longitudinal and circumferential direction of ellipse was estimated. Secondly, the measurement of the other point that was effected on the end surface shape was estimated.

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This paper describes a horizontal type twin roll strip casting process for producing aluminum alloy strip of A7075. Twin roll casting process is able to produce a strip from molten metal directly. Thus this process has a possibility to reduce total cost of sheet making comparing to conventional rolling process. Strip casting process has some disadvantages. Casting speed depends on the material properties. It is difficult to determine the casting conditions. Aluminum alloy A7075 has high tensile strength, and it is known as a material for aerospace application. The sheet is manufactured in small quantities comparing to the other sheet aluminum alloy. It is supposed that the demand of high tensile strength aluminum sheet such as A7075 is going to increase for weight saving of structural material. In this study, the effect of pouring temperature on the strip was investigated. Castability, surface conditions and strip thickness were estimated. It was possible to produce strip at any pouring temperature by horizontal twin roll strip casting process. Each surfaces of produced strip were transcribed form the roll surface, and the surfaces had a metallic luster. Minor cracks occurred at pouring temperature 710°C. Solidification cracking occurred at a pouring temperature of 740℃. The strip thickness of pouring temperature of 710℃ and 740℃ increased compared with the pouring temperature of 680℃. However, the strip thickness decreased at the pouring temperature of 770℃.

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This paper describes a horizontal type twin roll strip casting process for producing aluminum alloy strip of A5052. Twin roll casting process is able to produce a strip from molten metal directly. Thus this process has a possibility to reduce total cost of sheet making comparing to conventional rolling process. Strip casting process has some disadvantages. Casting speed depends on the material properties. It is difficult to determine the casting conditions. A 5052 is a typical alloy showing moderate strength among aluminum alloys. It is known as the alloy most frequently used for sheet among aluminum alloys. Because it has relatively high strength, excellent corrosion resistance, castability and weldability, it is used not only as a can lid material but also as a structural member of a vehicle and ship. In this study, the effect of pouring temperature was investigated. Castability, surface conditions and strip thickness were estimated. It was possible to produce strip at different pouring temperature by horizontal twin roll strip casting process. Each surfaces of produced strip were transcribed form the roll surface, and the surfaces had a metallic luster.

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This paper describes about cold plastic forming of ABS plastic pipe. Experiment and Finite element method (FEM) analysis of pipe expansion process were operated. The application of ABS plastic pipe for air conditioner is under consideration instead of metal pipe in Japan because of weight saving of air conditioner for lowering the gravity point against earthquake. The parts of ABS plastic pipe is generally produced by injection molding of hot working. The processes need the cooling time, and it takes much time. In addition, expensive mold die is needed for each application. Thus, cold plastic forming of ABS plastic pipe was proposed. Product ability of cold plastic forming is higher than the injection molding or hot working. And the punch and die shape is simple comparing to these process. In this study, pipe expansion process was operated. The ABS plastic pipe has a 10 mm diameter and 1 mm thickness. At first, true stress and true strain curves at any strain rate were measured by ring compression test. Obtained flow stresses was used to FEM analysis. Experimental device for pipe expansion process was made by Dip Inc.. Objective inner diameter was 10 mm. FEM analysis was operated to clarify the deformation behavior such as load-stroke diagram. It was possible to produce the expanded ABS pipe. The whitening of worked pipe was observed. Analysis result was indicated the good agreement comparing to experimental result in load-stroke diagram.

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Recently, boriding has attracted extensive attention as surface stiffening processing of plain steel. In this research, the influence of processing time on the formation layer of cold work tool steel (KD11MAX) by Al added fused salt bath was examined. In addition, in order to improve the abrasion resistance of cold work tool steel, the effect of the treatment of boronization on the formation layer has been investigated. Boriding were performed in molten borax which contained about 10 mass% Al at processing time of 1.8 ~ 7.2 ks (processing temperature of 1303 K). As a result of the examination, the hardness of the boriding layer becomes about 1900 HV when the processing time of 3.6 ks. Also the abrasion resistance has improved remarkably. Furthermore, it was revealed that the formation layer was boronized iron from the Vickers hardness and analysis of the X-ray diffraction measurement.

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The dendrite structure of the aluminum casting material has a complex three-dimensional structure. Therefore, it is impossible to conduct a sufficient investigation by the two-dimensional structure observation. The serial sectioning method used in this study, construct a three-dimensional structure image from two-dimensional images taken. The three-dimensional structure can be observed by this method. As a result of observation, it was confirmed that the dendrite has a growth direction. In addition, it was found that the shape of the dendrites varied by interfering with each other.

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The problem was that the pure titanium material could not be polished to be glossy surface even with conventional polishing. Although pure titanium was thought to be an single α phase, it was found from the previous study that β phase was contained in the surface. In this study, two kinds of specimens were prepared for comparison. One is processed and the other is not processed pure titanium proffered by the company. First, the specimens were polished and analyzed by XRD. Then the relationship between structure and abrasiveness was examined by observing the surface and measuring the surface roughness. Results showed that the β phase existed more not processed than processed on the surface of the material, furthermore, the change in the surface roughness after the finish polishing was compared. The amount of wear was more in the pure titanium material not processed than processed. As a result, it was found that the abrasive property was better when containing a certain amount of β phase.

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Ni-Ti alloy and Pt-W alloy are commonly used for medical material of catheters and guide wires. However, these materials have problems with allergy and cost. Therefore, Ti-Ta alloy which solves these problems. The effect on heat treatment was evaluated with hardness and structure observation using the Vickers hardness tester and microscope. The size of crystal grains gradually increased from 300℃ to 600℃ and rapidly increased from 750℃. It turned out the recovery, recrystallization, grain growth occurred during heat treatment.

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Spinning is a forming method which forms the flat disk metal into cylindrical metal. Spinning is also used to neck-form the tube end，such as the high-pressure hydrogen storage container．The 6061 aluminum alloy is used as a liner material of the container．The tube end of the liner is neck-formed by spinning without forming die．In this case， there is an issue that the forming defect may be introduced at the inner surface of container after neck-forming．It is considered that the defect in the forming is suppressed by spinning with forming die．However, such as a shape like a high-pressure hydrogen storage container, the mold can not be removed from the container after spinning. Therefor spinning is usually carried out without the mold. In this study, a removable mold which can be taken out after spinning applies for production of a shape like a high-pressure hydrogen storage container.

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Hydrogen embrittlement (HE) significantly reduces the ductility of metals and its mechanism has not been elucidated. Hydrogen embrittlement is caused by diffusible hydrogen but it is difficult to be observed. Tensile test was conducted on a ferritic stainless steel both with and without simultaneous cathodic hydrogen charging to examine the effect of hydrogen on the elongation to failure. About 35% of elongation to failure was obtained in the uncharged specimen with a dimpletype fracture surface. In contrast, when specimen was tested with simultaneous charging, the elongation decreased to about 8%, with a quasi-cleavage fracture surface. Thus, it was confirmed that HE takes place in this steel. In addition, a test piece was subjected to a tensile plastic deformation of 7% with simultaneous charging, aged at 25℃ for 168h, and then tensile-tested without hydrogen charging. By this treatment, the total plastic strain to failure was recovered to almost the original value, i.e., 35%. Hence, it is deduced that no undiffusible defect remains in the specimen after the tensile deformation of 7%.

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