We have been working on the development of scaffold free cell delivery system. Cells construct is made by spheroid-culturing the cells and neatly arrange the spheroids. Therefore, reproducible spheroids formation is required. The spheroids are made by dispensing cell suspension into a special multi-well plate. Then, shape of spheroids depends on the different number of cells and passage number. Therefore, the purpose of this study were to evaluate the spheroids shape made by skilled technician, and to make the spheroids reproducible using the robot developed. We used mesenchymal stem cell of rabbit. Upon reaching the required number of cells, we were dispensed into the special multiwell plate for forming spheroids. We analyzed the quantitative evaluation about spheroids. On the other hand, we incorporated the motion of the skilled technician to the robot developed. Because, in spheroid exfoliation by pipetting or stirring of cells turbid liquid, it is necessary to reconstruct the motions of skilled technicians with specialist knowledge and technique so as not to damage the cells. In result, by skilled technicians techniques be played on the robot developed, we can obtain the spheroids uniformity.

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This paper presents a measurement method for Young's modulus of cells based on directly squeezing cells. A microfluidic cell squeezing device is used for measurement of the Young's modulus of cell. This device is designed so as to control the magnitude of pressure to cells. This device is made of transparent materials which permit in-situ monitoring of cellular deformation behavior by an optical microscope. Mechanical stress is directly applied to the cell surface with the deflection of the PDMS film above the cell culture chamber. Cells were gradually deformed within an elastic deformation range when the mechanical stress was applied. After eliminating the applied pressure, these cells were returned to the initial shape. The osteoblastic cells (MC3T3-E1) were used as target cell to evaluate the Young's modulus. Young's modulus of the osteoblastic cell was determined based on the cell deformation and the applied pressure. The result of Young's modulus of osteoblastic cells obtained from directly squeezing experiment was similar to the published values.

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It is known that a single yarn is formed by spinning natural short fibers and a twist yarn consists of some single fibers in order to achieve high stiffness and strength of natural fiber composites. Generally, it is found that the amount of twist obtained by the spinning process, called twist per inch (TPI), plays an important role in yarn properties because the twist is essential to hold the fibers together. In fact, twisted yarns are normally used for increasing the lateral cohesion of the fibers and also for ease of handling. The purpose of this study is to investigate the effect of TPI of natural fiber yarns on adhesive estimation of interface for yarn reinforced green composites. The single yarn composites with three kinds of TPI from 3.5 to 9.5 were prepared. The fragmentation tests using these yarn composites under a polarization microscope were carried out. The multiple fiber breakages were experimentally confirmed, but the effect of TPI on the adhesive estimation was not cleared quantitatively. It was considered that the factors of these unwilling results were the twist angle, project and surface areas of fibers because the stress recovery length depends on these factors. In order to investigate the stress concentration of sound fibers and the adhesive estimation, some finite element analyses were conducted. From the analyses, it was found that the load shearing behaviors between sound fibers were different because the twist angle effects on the fiber axial direction change.

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It is necessary to form large reaction surface on electrode substrate of enzymatic bio-fuel cell to improve its power density. In this study, a porous carbon layer made of Ketjenblack (KB) was introduced into the enzyme immobilization electrode of a bio-fuel cell, and the effect of KB loading on the enhancement of electrode area and reaction promotion was evaluated based on cyclic voltammetry (CV) measurement. Furthermore, the operation test of the bio-fuel cell was also performed and the impact of addition of porous carbon layer on the cell performance was investigated. It was found that the introduction of porous carbon layer into enzymatic electrode of bio-fuel cell enlarges actual reaction surface and improves limiting current density. The formation of large cracks in the porous carbon layer has a small influence on the cell performance.

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A biomimetic sealing system specialized in separation between air and water has been developed with two hydrophilic seal lips and non-Newtonian fluid as lubricants. The seal lips were made of polyvinyl formal (PVF) whose structure is similar to that of articular cartilage of a natural synovial joint. The lubricants were aqueous solution of polyethylene glycol, which correspond to natural synovial fluid. In the previous study, this sealing system showed lower frictional torque than an oil seal and a mechanical seal for rotating shaft at 20 rpm under 0.8 MPa water pressure without water leakage. In order to cover higher speed operation, original PVF seal lips were reinforced by non-woven fabric made of polyester. Pressurization test up to 0.8 MPa water pressure to evaluate frictional and waterproof functions was conducted at 100 rpm rotation. The effectiveness of fiber reinforcement to PVF seal lips was elucidated and the sealing system was superior to oil seal even at 100 rpm rotation.

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In flying insects, dragonfly has especially high flight performances which are high speed flying, hovering, turn sharp, and so on. Therefore, dragonfly has been expected to be applied design guide for developing MAV used in disaster area. For this reasons, our researches has focused on dragonfly flight mechanisms for developing MAV with high flight performance. In this study, for clarifying the dragonfly flight mechanisms, the pressure over the wing surface were measured with test wing in one wing mode and glider mode like real dragonfly gliding. From this measurement result, the pressure over the hind-wing surface was made a change by the fore-wing located. We considered that the fore-wing changed air flow direction. Moreover, real dragonfly may cause equal change in gliding.

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Recently, flight characteristic of dragonfly has been investigated by many researchers. Dragonfly has high flight performances in spite of small size. Dragonfly wing has about 3000 of micro spikes of which length is about from 10 to 100μm. It is believe that these micro structures affect the flight characteristic of dragonfly. In this study, a plate with micro spikes was fabricated, and the pressure drag of the vertical flat plate with micro spikes was measured. The artificial spikes were fabricated the same size as dragonfly wing. The measurement of drag force was carried out with the flat plate with spikes and without. As a result, effect of micro spikes was appeared at low Reynolds number of from 1000 to 2000.

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This paper reports on measurement method of aerodynamic force of a fruit fly (Drosophila) during flapping motion using a MEMS (Micro Electro Mechanical Systems) multi axis force sensor. The proposed MEMS multi axis force sensor is composed of a Si probe and supported beams whose surface or sidewall area is doped to measure 3 axis forces and moment around the probe. The sensor size is approximately 1800 μm × 2800 μm × 35 μm. The force and moment resolution are designed to be under 1 μN and 1.0 μNm, respectively. The aerodynamic force vector can be detected by attaching a fruit fly to the tip of the probe. Using the fabricated force sensor, we developed sensor attachment setup and experimental setup to measure aerodynamic force of a fruit fly.

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Most of insects that walk about on the ground have structures to fold their wings. In this study, the take-off motion of a paper wasp, Polistes chinensis, was observed with a high-speed video camera system, and the unfolding sequence of the wings was investigated. A paper wasp with a body length of 13.8 mm was used. The wasp opened the folded wings and started flapping, and then the wing unfolding was completed at the third down stroke. The down stroke time decreased and upstroke time increased until each third stroke. Therefore, the initial several up and down strokes seem to be conducted to unfold the wings. The behavior of the vertical climbing flight following to the take-off was also investigated. The incline of the body to the horizontal was kept at around π/4 in the whole period of the vertical flight. Although the up and down stroke directions were almost parallel to the horizontal, the trajectories were different from each other. The trajectories of up and down strokes were convex upward and downward, respectively.

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This study is that I make the robot which imitation of a phase difference and evaluated the influence on flight in the phase difference of four pieces of feathers with wind tunnel test and animation analysis.

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Upon oxidization and reduction, the conducting polymers change the physical properties as swelling or shrinking. The change of the dimension is induced by the electrochemical cycle, which is called electrochemomechanical deformation (ECMD) and can be utilized as soft actuators. Many researchers have already reported the ECMD in conducting polymers, such as polyaniline (PAn), poly(o-methoxyaniline) (PmAn) and polypyrroles (PPy). In particular, polypyrrole-based conducting polymer soft actuators are constructed from high-quality film. However, these actuators need ions and solvents and work in the electrolyte solutions. In this study, the authors proposed a conducting polymer soft actuator, based on polypyrrole, worked in the air condition. The five layers conducting polymer soft actuator worked in the air is fabricated by simple electro polymerization and is evaluated the basic characteristic, the angular velocity, the specific electrical energy and the durability.

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Bacterial cells' behavior in which they accumulate around a source of chemical attractant was modeled as a biased discrete random walk. In this model, a model cell straightly moves during a certain period with a determined speed. After the motion, the model cell changes its direction in a random choice. Then, the model cell again moves in the determined direction. A parameter a was introduced to include biased effect in the model. When a model cell approached the chemical source in the previous step, the cell will continue to move in the same direction with the probability α, or the cell randomly change its direction with the probability (1-α). Numerical simulations for the motion in 2D plane were performed. They revealed that the distribution of the model cell is like an exponential distribution with an index related to α. This indicates the potential of this model to express the strength of bacterial chemo-taxis in terms of α.

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We have been focused on the dispersion of cells in micro channel flow, especially red blood cells (RBCs). When RBCs are dispersed in a micro channel with a Y-shape junction, the dispersion of cells would occur from denser to thinner direction according with concentration of cells. It is regarding to clarify the dispersion phenomena in micro channel for designing of lab-on-a-chip applications. The detailed mechanism of cell dispersion, however, has not been fully clarified yet. We performed the quantitative dispersion measurement in the Y-shape micro channel, in which two layers with and without RBCs flow in parallel, and investigated the effects of flow rates and hematocrit. Our results suggest that the dispersion in micro channel would be more dominant than Brownian diffusion, and depends on the hematocrit and the flow rate. These findings provide us useful information on mass transport in cell suspensions.

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In late years a function and the structure of the creature called biomimetics are applied to technical development. We focused on the tuna that could swim in the water at high speed. A saw-like fin is between the tail and fins from the 2nd dorsal fin in fish like tuna. A fin of the triangle is called finlets, and there is in the back and ventral. It is thought that the finlet brings the effect that the flow behind the fish rectifies at present. Its role was inspected experimentally by visualization experiment by smoke tunnel and fluid force sensing using a made model. The experimental result by the smoke tunnel was not seen in the variation of the flow with or without finlet. In addition, in the fluid force measurement, the one when equipping finlets more than the time of non-equipment, indicated a more expensive C_D.

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The swimming motion of Tuna type fishes has excellent ability for its speed and efficiency. In the former studies, we made 1/1 scale model of Blue Fin Tuna body and caudal fin. The body resistance in the water flow are measured, and the lift and drag force of caudal fin are also measured. By using these data, we developed swimming mechanism and mounted on float, This paper shows a performance comparison between Tuna type caudal fin and Rectangular caudal fin.

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We investigate the infiltration flow in a soil-model to understand the influence of grain size of a soil. The soil model consists of glass beads between two thin glass plates. We visualized the infiltration flow with this model. We carried out the experiment with the different diameters of glass beads for the model. We use five types of different diameters on glass beads whose diameters are similar to those of real sand constituting a soil. The results show that the vertical velocity in d = 1.3mm of diameter on glass beads is the maximum for infiltration. The diameter d = 0.10mm of glass bead gives wider infiltration than the bigger ones. The direction of infiltration relates the ratio between volume on void of soil model and volume of supplied water. The wider infiltration flow causes when the volume flow rate is larger or grain of soil is smaller.

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Lymph node (LN) metastasis plays an important role in the development of distant metastasis to vital organs. For LN metastasis, administration of anti-cancer agents is a standard treatment, but it has been a problem about strong side effect and low treatment effect. In the present study, we propose a drug delivery method via lymph network for metastatic LNs. It has a potential to be an effective treatment for targeting LNs and low side effect. We used MXH10/Mo-lpr/lpr mice, which develop systemic swelling of lymph nodes up to 13mm in diameter, similar in size to human lymph node. We demonstrated a molecular can be delivered into the metastatic LN via the lymphatic vessel. Our results may help development of an effective new lymphatic drug delivery method.

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The status of tumor-draining lymph nodes (LNs) is a prognostic factor for determining the cancer stage and thus treatment planning. As treatment of lymph node metastasis (LNM), chemotherapy or radiotherapy has been used. However, there have been no reports of evaluation methods of chemotherapy induced anti-tumor effect on metastatic lymph node (MLN) using non-invasive methods. Here we show intranodal pressure (INP) can evaluate the treatment effect on MLN using the mouse model of LNM, MXH10/Mo-/lpr/lpr mice. We found that INP increases in control while chemotherapy induced reduce INP. These results demonstrate that change in INP is related with the anti-tumor effect on LNM. We anticipate that INP is low invasive and may evaluate the antitumor effect on LNM with radiotherapy as well as chemotherapy.

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Cancer is one of the major diseases that cause death all over the world, especially via metastasis. Systemic drug administration to treat metastatic lymph nodes are not so effective and cause side effects. In our laboratory, we have studied on a novel drug delivery system, combining nano/microbubbles with ultrasound (US), which shows considerable potential for the delivery of exogenous polymeric molecules into lymph node cells through the lymphatic sinus. In this study, we selected some fluorescent molecules which had different molecular weight (MW) as exogenous molecules, and verified delivery efficiencies depending MW. We found that induction dose into lymph node cells has relationship with molecular weght.

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In order to develop drug delivery systems (DDS) using liposomes, it is important to understand the effects of mechanical stresses on the water permeability of liposomes. We perform a series of molecular dynamics simulations of stretched palmitoyl-oleoyl phosphatidylcoline (POPC) lipid bilayers, which is the fundamental shell component of the liposomes. The stretched bilayers are simulated by constant temperature and bilayer normal pressure MD simulations with various constant areas. Under stretching, the bilayer thickness becomes thin. In the core of the bilayer, the lipid density increases, resulted in the smaller diffusion coefficient and the larger potential of mean force of water in the core region. This leads to the increase in the local resistance for water permeation. However, the apparent water permeability, which is the inverse of the integrated value of the resistance profile across the bilayer, shows the increase trend as the thickness decreases, although it depends on the applied stretch. This indicates that the water permeability and the permeation mechanism might be affected by mechanical stresses. As the DDS liposomes experience various mechanical stresses during blood circulation, it may be important to evaluate the leakage of drugs from the liposome considering the history of the stresses and the apparent permeability change.

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Acoustic liposomes (ALs), which are microbubbles coated by lipid membrane, are observed in a standing sound field of 110 kHz with a high speed video camera. The ALs reveal the surface oscillations of nth mode (n = 3,4, 5, 6, 7) with a half period of the sound field. It is shown that the surface oscillations are induced by the parametric excitation. The parametric excitation condition obtained from the natural frequency of surface oscillations caused by surface tension leads to decrease of surface tension of ALs. The experiments of applying sudden pressure increase are also conducted on the same ALs as observed surface excitation in the former experiment applying sound waves. The buckling of surface area is observed on the AL's surface in the latter experiment, which can be a proof that the ALs in the former experiment is really coated by the lipid membrane. The influence of the lipid membrane on the AL's behavior in the sound field causes the decrease in the surface tension of the bubble surface.

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Glioma remains one of the most deadly malignancies, for which efficacy of traditional chemotherapy is often limited due to the blood-tumor barrier (BTB). Thus, the development of a method for enhancing the BTB permeability is highly needed. In this study, we used a nanosecond pulsed laser-induced photomechanical wave (PMW) to enhance the permeability of BTB in a rat intracranial glioma model using C6 cells. A tumor was grown in the both hemispheres, and a solution of Evans blue (EB), as a test drug, was injected into the tail vein. Thereafter, a PMW was applied to one hemisphere through the cranial window and the other hemisphere served as a control. Four hours later, the rat was perfused and intensity distributions of EB fluorescence in the brain were imaged. We examined the optimum PMW pressure for safe and efficient drug delivery by changing the laser fluence, showing that the application of a PMW with a peak pressure of 〜54 MPa enabled efficient, damage-free delivery. On the basis of fluorescence microscopy, we also confirmed that a drug was delivered into targeted cells in the peripheral region of the tumor by using enhanced green fluorescent protein-expressing C6 cells.

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Recent years, the drug delivery systems (DDS) require multi-functionality and high functionality. In this study, we synthesized a multifunctional DDS composed of magnetite nanoparticles core and mesoporous silica shell (Fe_3O_4@mSiO_2) for magnetic resonance imaging and hyperthermia. We evaluated the magnetic characteristics and the heat dissipation characteristics of the Fe_3O_4@mSiO_2 nanoparticles. As a result of the magnetic characteristics evaluation, it was confirmed that Fe_3O_4@mSiO_2 nanoparticles had magnetism. The heat dissipation characteristics of the Fe_3O_4@mSiO_2 suspension were also measured by exposing a magnetic field strength and frequency of 5.08 kA/m and 415 kHz respectively. For a specific time, the Fe_3O_4@mSiO_2 nanoparticles exhibited a temperature rise of 20K. These results imply that the synthesized Fe_3O_4@SiO_2 has potential applications in magnetic resonance imaging and hyperthermia.

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Effect of maximum test temperature on crack propagation behavior of an Austenitic cast steel during Thermo-Mechanical Fatigue (TMF) tests was explored under the In-Phase(IP) and Out-of-Phase(OP) conditions. The behavior was comprared with that of isothermal low cycle fatigue. The experimental results clearly showed that additional mechanism(s) mechanism to pure fatigue begun to work, when the maximum temperature get higher enough. It was also shown that not only the mechanical factors but the microstuructural features;e.g., microsegragation around dendritic boundaries, played an important role in the crack progation process.

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Effects of phase difference of loading waveform and slit geometry of specimen on high temperature fatigue crack growth of SUS304 stainless steel were examined under multiaxial loading conditions. Fatigue crack growth tests were conducted by using thin-walled cylindrical specimen and DC electrical potential drop method. It was found that crack growth rate under the out-of-phase loading is slower than that under in-phase loading. Slit geometry influences degree of the effects of phase difference on crack initiation, as well as fatigue crack growth. These tendencies result in the characteristics of fatigue life which increases under the out-of phase loading. Concerning to the effects of slit geometry, in case of the slit of low stress concentration, crack initiation life increases and fatigue crack growth rate is decelerated.

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In the previous report, it was found, from fatigue tests using notched round bar specimens, that critical distance approach is available for fatigue life prediction at stress concentration part at low cycle regime. In this study, in order to confirm the capability of the life assessment method for stress concentration part at contact edge such as dovetail structure in gas turbine disks, fatigue tests using the dovetail structured specimens with contact configuration of Ni-based single crystal superalloy were conducted at high temperature. Critical distance, which means the region of stress field related to the fatigue process zone, was obtained from fatigue tests and analyses using notched round bar specimens. The average stresses within the critical distance at the contact edge, where fatigue crack initiates, for dovetail structured specimens were obtained. It was found that the fatigue life of dovetail structured specimen can be predicted within the almost factor of 2 scatter bands by life assessment method using the average stresses.

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The hardness of nickel-base superalloys for gas turbine blades makes it difficult to observe striations which indicate crack growth rate on fatigue fracture surface. In this paper, the low cycle fatigue crack growth tests using a single crystal Ni-base superalloy at a high temperature were carried out, and an attempt was made to estimate the crack growth rate by the Electron BackScatter Diffraction (EBSD) observation on a vertical cross-section including the crack. As a result, it was found that by the EBSD observation striations were observed along the crack and the striation spacing indicated the fatigue crack growth rate with a high degree of accuracy.

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Directionally solidified Ni-base superalloy have been developed as a gas turbine blade for high efficiency thermal power plant. Gas turbine blades are used under the conditions of high temperature creep. It is considered that creep crack growth behavior and its life of directionally solidified Ni-base superalloy will be affected by crystal orientation around a crack, since directionally solidified Ni-base superalloy has different crystal orientation. In this study, in order to clarify the scatter of crack growth life of directionally solidified Ni-base superalloy, the designed two-dimensional elastic-plastic creep finite element analyses were conducted to clarify the effect of crystal orientation on creep crack growth.

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Damage assessment method of gas turbine hot-gas-path components such as blade and nozzle was required to evaluate remaining life of these components; especially, the method of size estimation of inelastic deformation zone is important for structural integrity assessment. In this study, in order to provide the way for evaluating the plastic deformation zone analysis of gas turbine hot-gas-path components, X-ray diffraction experiments were performed for tensile deformed Ni-base single crystal superalloys using synchrotron radiation at SPring-8, and the relation between applied tensile strain and X-ray diffraction peak width was studied. X-ray diffraction peak width increased with the increase of applied tensile strain. Williamson-Hall analysis was applied to calculate microstrain. Microstrain showed drastic increase in the early stage of tensile tests. It suggests that the measurement of microstrain by X-ray diffraction is useful for size estimation of inelastic deformation zone.

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Creep damage preferentially proceeds at stress concentrated portion such as notch roots under multiaxial stress states in high temperature components. It is necessary to establish creep damage assessment methods under these conditions for maintaining safety operation. So far, influence of notch on creep rupture strength, and damage condition at notch root after testing were reported. However, damage extension process at notch root is not clarified and argument of damage assessment methods is still on going. In this study, creep tests were carried out using the circumferential notch specimens on a CrMoV forging steel. Damage conditions at the notch root were observed with interrupted test specimens. Damage assessment by using the miniature creep specimens taken from damaged notch specimens was conducted. It was found that the location where the void number density is the largest is corresponding to the location where both the axial stress and the triaxiality factor yield the maximum values. The creep damage given to the notch specimen was underestimated by the subsequent miniature creep test, when creep voids initiated in the creep damaged specimen do not give any influence on ductility reduction for the miniature specimen.

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Recently, many heat resistant materials have been developed to establish more efficient thermal power plants. For practical use, it is necessary to establish a law of predicting the crack growth life and clarify the behavior of micro damage formation. Stress- and strain-controlled creep-fatigue tests have been conducted to investigate the crack growth life of the material in the thermal power plants. The fracture mechanism under high temperature, such as micro damage formation, is affected by vacancy diffusion. In this work, we conducted the numerical analysis of vacancy diffusion in order to clarify the behavior of vacancy diffusion caused by stress- and strain-controlled creep-fatigue conditions. In comparison with experimental results, the following results are obtained. Under stress-controlled condition, the concentration of vacancy around a notch tip increased with increasing loading cycles., which results in progression of creep damage. Under strain- controlled condition, the concentration of vacancy did not increase around a notch tip, which suggests fatigue damage becomes more dominant.

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Polycrystalline Ni-base superalloys are used for turbine blades in power plants and jet engines. In order to ensure safety in these systems, clarifying the behavior and mechanism of creep damage formation is highly in need. Thus in this study, elastic-plastic-creep finite element analysis combined with vacancy diffusion analysis was conducted for polycrystalline Ni-base superalloy model in order to mechanically examine the creep damage formation behavior. FEM and vacancy diffusion were combined in this analysis in the interest of considering both macro and micro damages. As the result of the analysis, damage caused by plastic deformation and vacancy, which forms voids when coalesced, were found to accumulate at grain boundary, which eventually lead to intergranular cracking. Furthermore, by combining FEM and vacancy diffusion analyses, macro damage region was detected by FEM analysis, and micro damage region within the macro damage region was detected by vacancy diffusion analysis.

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Since tubes, used in superheater or reheater of thermal power plant boiler, are used at an elevated temperature for a long period of time, occurring of creep damage and oxidation thinning are concerned. Although it is important to grasp a temperature in use for securing the soundness of equipment, since number of tube is large and installed in the furnace, it is difficult to carry out a temperature measurement by thermocouple etc. It has been reported, when the low alloy steel (2.25Cr-1Mo, STBA24) widely used for piping or tube is exposed to elevated temperature for long term, the area (PFZ, Precipitates Free Zone) in which carbide disappeared near the grain boundary will be formed, and from measurement of PFZ width, it is possible to presume the mean operating temperature in period of use. The above-mentioned technique is applied to boiler tube scrap wood, and tried to presume operating temperature. Moreover, technique of presuming the residual life of tube from the presumed temperature, in consideration of oxidation thinning, is developed.

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For instrumentals used at high temperature for long term, such as steam turbine of thermal power plant, it is indispensable to grasp these deterioration states, since a material deterioration of softening, causes strength reduction and embrittlement leads to a falloff of tolerance crack length, etc., advances gradually, even when the creep or creep fatigue are not actualized, in order to prevent a destruction. Although it has been reported, at the hot section with the operating temperature higher than 500 ℃, tensile and creep strength fall together with softening, the knowledge which is needed for future operation management, whether deterioration state will advance with increasing speed or saturate etc., is not acquired. In this study, for the reheat stop valve scrap wood used for more than 300,000 hours, we carried out a hardness testing, charpy impact test, etc., and investigated the deterioration and embrittlement status.

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The commercialization of a 700℃ class pulverized coal power system, advanced ultra-supercritical (A-USC) pressure power generation, is the target of an ongoing research project in Japan. In the A-USC boiler, Ni or Ni-Fe base alloys are used for high-temperature parts at 650-700℃, and advanced high-Cr ferritic steels are planned to be used at temperatures lower than 650℃. In the dissimilar welds between Ni base alloys and high-Cr ferritic steels, Type-IV failure in the heat-affected zone is a concern. The high B-9Cr steel developed at the National Institute for Materials Science, which has improved creep strength in both base metal and weldment, is a candidate material for the Japanese A-USC boiler. In the present study, long-term creep tests were conducted on the dissimilar welded joints between Ni base alloys and high B-9Cr steels. Microstructures and creep damage in the dissimilar welded joints were investigated. The creep rupture life of the dissimilar welded joints using high B-9Cr steel was 5-10 times longer than that of the conventional 9Cr steel welded joints at 650℃. The effect of welding procedure was also investigated.

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Heat-resistant steels used in thermal power plant require periodic inspections for safely operation. In order to determine the period of inspection interval, it is necessary to predict not only creep crack growth life, but also creep crack initiation life, which is the time when crack length takes some specified value. Furthermore, it is also necessary to evaluate not only the life of base metals but also that of weld joints which are contained in actual structures. In this research, the life of creep crack initiation for both of base metals and weld joints are evaluated.

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The effect of sampling location on SPC(Small Punch Creep) tests were investigated for weld joints to establish evaluation method of TypeIII and Type IV creep behavior. The SPC specimen shape was 10mm diameter and 0.5mm thick round disc prepared from weld joints of 2.25Cr-1Mo low alloy steel. It was found that the center of SPC specimen should be 1mm apart from the weld interface for Type III creep damage evaluation and 2mm apart from the weld interface for TypeIV creep damage evaluation as the recommended sampling location.

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Large sized creep rupture and interruption tests were performed for specimens made from ASME T92 thick plate weld joint. For one specimen, creep test was continued till rupture. For another specimen, creep test was interrupted at 60% and 70% of estimated creep life time, 10,000 hours. Rupture time was almost comparable to that of published creep data acquired by standard size specimens. Type IV damage was observed for both, ruptured and interrupted specimens. SEM observations revealed that a number of micro-voids were nucleated at grain boundary of FGHAZ. On the same specimen, growth and cross-linking of micro-voids, heavily damaged and almost separated grain boundaries and grain-sized voids were also observed. These microstructural features were considered to show Type IV damage evolution. An importance was indicated to detect and consider early stage damage, i.e. micro-voids, grain boundary separation, to evaluate residual life of actual component from the earlier stage of usage.

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At the present time, many Extra Super Critical Pressure Boiler are made by 9%Cr steel for thermal power station in Japan. these power station have been in operation for a total of over 100,000 hours, Actual-Size Burst Equipment capable of reproducing actual equipment damage (Type IV damage)and FEM are used to solve this burst mechanism. Worlds first time, Residual Life Assessment Method from middle Life able to use Welding part at 9%Cr steels was developed. Type IV mechanism for 9%Cr Welding Part was solved. We tried to search Burst Extend of Multi Axis (εf) from each Company Test Date. In the result, It was about all same value 1.16. Steady strain rate (εmin) is measured by Laser Device that consist of usual setting target and main body setting at Periodic Inspection. Heat Influence for HAZ in TIG Welding of Laser Device Fitting Set was little, 1mm depth. We confirmed accuracy of this method using Mono Axis Test Piece, In the result, Burst Time expected by this one is 4926hours, Real Burst time is 5000 hours, Its accuracy is Factor of 1.015. In conclusion, We developed high accuracy Residual Life Diagnosis Method in the worlds first, It is consisted of combination Strain considered Multi Axis Burst Extend and Micro structure in 9%Cr steel HAZ

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In nuclear power plants, a lot of failure cases by high cycle thermal fatigue were reported, which was induced by temperature fluctuation of the coolant. To ensure the safety of nuclear power plants, thermal fatigue damage should be evaluated adequately. For evaluation of thermal stress due to fluid temperature change, frequency response function was developed by Kasahara et al.. This function can evaluate thermal stress caused by thermal stratification oscillation, which is one of typical causes of high cycle thermal fatigue. However, the function was proposed under the ideal condition where the thickness of stratification could be ignored. Thus temperature distribution in direction of vertical to thermal stratification is not considered enough. Consequently, calculated thermal stress could be too conservative. Therefore influence of the thickness on occurrence mechanism of thermal stress was investigated by conducting finite element simulation. Based on the clarified mechanism, the frequency response function was improved for adequate evaluation of thermal stratification. By using the improved function, stress time series can be obtained, from which thermal fatigue damage was evaluated.

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At the present time, many Extra Super Critical Pressure Boiler are made by 9%Cr steel for thermal power station in Japan. these power station have been in operation for a total of over 100,000 hours, Actual-Size Burst Equipment capable of reproducing actual equipment damage (Type IV damage) and FEM are used to solve this burst mechanism. Worlds first time, pipe-reinforcing technique that used band steels etc. for Welding part at 9%Cr steels was developed, it was that was not welded. It was developed 3 types, (1)Winding Band Steels (for inner pressure) (2)One touch Flange(for inner pressure) (3) One touch Flange(for bending moment). Band steels can wind for every shape, Therefore, It is very easy methed,but,it is easy to be individual differences Type IV damage for 9%Cr Welding Part was reduced. It resulted that Life could extend for high temperature boilers.

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Bivariate log-normal distribution analyses were conducted on the specific output class of steam turbine components such as rotors, moving blades, nozzles, casings. The damage phenomena were erosion, creep deformation, fatigue cracking, fouling, scoring and so on excluding the repeated events after repairmant. Time and cycles to the occurrence of each event were regressed as log-normal type distribution function respectively but either contribution should not be ignored. Then bivariate log-normal type distribution functions were applied to the event data and proved to be almost successfully identified to represent the distribution characteristics. The quadratic exponent Q of the bivariate log-normal distributions was introduced to show the equi-probability contours of time and cycles and used to evaluate equi-risk functions where the consequence was attributed to the cost of repairment. There after total bivariate risk functions was established and the total optimization of repair cost regarding to time and cycles pattern of steam turbine plant. This tool was proved to be useful for realizing notional maintenance planning in actual components.

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Containment vessel is an important structure to prevent a significant and sudden radioactive release under the severe accidents. In case of the severe accidents, the pressure generated in the containment vessel is supposed to exceed the maximum design pressure. The required function of the containment vessel as radiological confinement should be enhanced, as far as reasonably achievable. To clarify the progress of events under the severe accidents and design the severe accident countermeasure equipment, it is necessary to evaluate the pressure toughness of containment vessel boundary adequately. The containment vessel of fast reactor is composed of the various structures, and the one of the most thin boundary structure is bellows structure to absorb the thermal expansion of the coolant piping penetrating the containment vessel. In addition, the cover gas bellows of the intermediate heat exchanger has important role when the progress of the events under the severe accidents is considered. Therefore, in order to develop the evaluation method of the pressure toughness under the severe accidents, the burst pressure tests of the bellows structure subjected to internal pressure was performed.

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Containment vessel is an important structure to prevent a significant and sudden radioactive release under the severe accidents. In case of the severe accidents, the pressure generated in the containment vessel is supposed to exceed the maximum design pressure. The required function of the containment vessel as radiological confinement should be enhanced, as far as reasonably achievable. To clarify the progress of events under the severe accidents and design the severe accident countermeasure equipment, it is necessary to evaluate the pressure toughness of containment vessel boundary adequately. The containment vessel of fast reactor is composed of the various structures. The head plate that is primary and secondary coolant boundary in intermediate heat exchanger has important role when the progress of the events under the severe accidents is considered. Therefore, in order to develop the evaluation method of the pressure toughness under the severe accidents, the burst pressure test of the head plate subjected to convex side pressure was performed, and burst pressure test was evaluated by FEM analysis.

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In recent years, there has been a growing momentum to the hydrogen energy spread. One of use of effective hydrogen energy is a fuel cell vehicle, therefore development and social implementation of fuel cell vehicles has been promoted. One of the challenges of social implementation of fuel cell vehicles is the establishment of safe hydrogen fueling stations. This solution is a safety assessment in hydrogen fueling stations. Safety measures must be incorporated into the stations. In this study, from the results of HAZID analysis, we made an examination of probability by ETA and estimated the influence of the safety measures in hydrogen fueling stations. As a result, we were successful in the quantitatively evaluation of the impact of safety measures that were unclear in the HAZID analysis. And we confirmed the validity of the results of HAZID analysis in the hybrid gasoline-liquid hydrogen fueling stations and Usefulness of HAZID analysis in the safety evaluation of hydrogen fueling stations.

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A Japanese motor corporation has been selling commercial fuel cell vehicles since December 2014. Therefore, it is necessary to establish hydrogen infrastructure, particularly hydrogen fueling stations. In this study, for the safety management of hybrid hydrogen-gasoline fueling stations, the simulation of gasoline pool fire was conducted using the codes Toxic Release Analysis of Chemical Emissions and ANSYS. Based on the analysis results, the safety of liquid hydrogen storage tanks was discussed. On the side near the pool fire, the temperature of the tank increases with the increase in exposure time, whereas, on the opposite side, the temperature remains unchanged. Thus, the temperature distribution on the tank induces thermal stress. Moreover, the thermal stress is higher than the yield strength in case that the distance between gasoline pool fire and tank is short. Thus, it is important to consider not only the strength decrease due to high temperatures but also the thermal stress due to temperature distribution.

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Here the present paper proposes a method employing micro-area X-ray diffraction analysis to evaluate local hydrogen concentration behavior. Hydrogen concentrating around a crack tip significantly accelerates crack propagation in metals, i.e., hydrogen embrittlement. The concentration behavior of hydrogen has not been revealed yet. In order to solve mechanism of hydrogen embrittlement, hydrogen concentration behavior in local area, e.g., a crack tip, has to be cleared by not only a numerical analysis but also an experimental approach. The present study takes notice of hydrogen-induced lattice strain and X-ray diffraction was employed to detect variation of lattice spacing before and after hydrogen charging. Here we demonstrate using X-ray diffraction applied to a micro area that hydrogen concentrates around an elastic-plastic boundary at vicinity of a crack.

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In the near future, hydrogen energy is expected to become a practical energy source. However, it is known in previous studies, that steels become brittle and fractures early in hydrogen environment. This phenomenon is called hydrogen embrittlement, and it has become a problem for hydrogen energy to become a practical energy source. In order to prevent hydrogen embrittlement, it is necessary to understand fatigue crack growth behavior in hydrogen environment. Thus in this study, we conducted crack growth analysis using the value of hydrogen concentration obtained by hydrogen diffusion analysis. The objective of this analysis is to investigate the effect of work hardening coefficient on crack growth behavior in hydrogen environment. As a result, it is found that the hydrogen concentration around a crack tip with higher work hardening coefficient is higher than that with lower work hardening coefficient. This phenomenon cased the increase of acceleration rate of fatigue crack growth rate in hydrogen environment. These results showed that the material which has low work hardening coefficient have a resistance for hydrogen embrittlement at the crack growth process which is different from that of a notched specimen.

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