Fluid flow in a microscale field is drawing attention due to engineering scale miniaturization and measurement technology development. Therefore, it is necessary to observe the flow in the vicinity of the wall surface along with this scale miniaturization of flow field. With this, a research using an evanescent wave illumination microscope has been conducted. This microscope can only observe fluorescent particles within the region of several hundred nanometers from the wall surface by using the evanescent field generated by the total reflection of the laser light. In this study, I will explain what can be visualized with evanescent light, showing advantages and disadvantages. Further, I will explain how to obtain the velocity profiles from the observed data.

The study on removal mechanism of nanoparticles near to polished wafer surface is necessary to efficiently clean the nano-particles from the wafer in semiconductor manufacturing process. An optical method has been applied to visualize only the nano-particles moving near to a surface by an evanescent field. We generated the evanescent field locating in limited range from the film surfaces by reflecting a laser beam at an incident angle larger than critical angle. The removal phenomena of the SiO₂ particles (105 nm) on the BK7 glass surfaces were observed by our developed experimental setup. The SiO₂ particles removal with ultrasonic (approx. 1 MHz) was demonstrated.

PVA brushes are frequently used for a cleaning of the post CMP process. In the cleaning process, the contact conditions between the brushes and surface is very important, however the direct observation is difficult task. In this study, we have tried to observe the real contact area between PVA brushes and prism surface using total reflection light. As results, a high contact area region at the front part of the brush moving was observed, and the region was formed by catching the brush side face. In addition, the real contact area of PVA brush with surface skin layer was about 0.6 % compare to the appearance contact area.

PVA brushes are widely used for cleaning after CMP process in the semiconductor manufacturing. The PVA brushes have a high cleaning ability, but it sometimes become an origin of surface contamination owing to the attachment of the brush itself. The purpose of this study is to measure the adhesion force between PVA brushes and a flat plate. We compressed the PVA brush to flat plates with different wettability for several time and measured the adhesion force between the plate and brush during pulling up using a high response road cell. As a result, we confirmed that the combination between a PVA brush with skin layer and PMMA plate shows high adhesion force than other material plate. And we also confirmed that the adhesion force increased with increase the compression time. On the other hand, such high adhesion force could not be measured with a PVA brush without skin layer.

Particle behavior on flat plate in narrow flow channel was experimentally investigated. As the test particle, polystyrene particle, glass particle, TiO₂ and SiO₂ powder were used and compared differences in behaviors for each particle. Number density of particles was measured using the microscope camera. Relatively large particles were removed from the wall surface to upper layer of the flow by the effect of lift force. However, the small and high density particles such as the TiO₂ powder, could not remove from the wall surface. In addition, the difference in particle velocity for each particle diameter in a steady flow was measured using polystyrene at near the wall surface and center of narrow flow channel. At near the wall surface, large particles trended to move faster than small particles. At center of narrow flow channel, particle velocity was constant regardless of particle diameter. At near the wall surface, large particles was affected by the velocity distribution by shear layer and move faster than small particles.

Particle removal characteristics from the wafer surface by water jet including small bubbles were investigated experimentally. Wafer of TEOS film was used as the test wafer. Polystyrene partcles, SiO₂ powder and TiO₂ powder were used as a test partcles. Effect of micro-bubble and small bubbles (millimeter side bubbles) were investigated on the particle removal characteristics. As the results, it was confirmed that the small bubbles were effective to remove the SiO₂ particles from the TEOS wafer surface. However the removal of TiO₂ particles was difficult when the small bubble was used.

We created polymer coated wall surfaces with different concentrations of coating solutions and investigated their influence on flow resistance. Polyvinyl alcohol (PVA) and polyethylene oxide (PEO) were used for the polymer coating. Experiments were conducted using a rectangular channel and the flow resistance was evaluated by measuring the pressure loss of the channel. For the wall surface coated with only PVA, the flow resistance increased by approximately 30%. When coated with PVA and PEO, changing the concentration of the polymer coating solution did not affect the pressure loss for Reynolds numbers greater than 3000. In the region where the transition to turbulence occurred, the wall surfaces coated with high concentration polymer solution delayed the transition slightly.

A liquid droplet can hover over a solid surface that is heated above the Leidenfrost point (LFP), at which an insulating vapor layer is formed that acts as a heat transfer barrier. Recent studies have reported that hierarchical surface textures, which combine microscale and nanoscale textures, provide high wettability and significant LFP enhancement. However, the fabrication of such textures is often difficult and expensive. In this study, LFP enhancement through usage of low-cost hierarchical textures is experimentally demonstrated. The surface textures were fabricated by coating SiO₂ nanoparticles on stainless steel wire meshes. To determine the LFP value, the droplet lifetime method was employed for the temperature range of 200 °C to 490 °C. High-speed imaging (4000 fps to 23000 fps) was also conducted for visualizing the impact behavior of a droplet. It is observed that the LFP value of the nanocoated mesh surface is greater than 490 °C. Such enhanced LFP is 178 °C higher than that of a stainless steel surface and 38 °C higher than that of a single layer textured surface. Furthermore, with respect to the said LFP enhancement, explosive impact behavior of a droplet can be observed on the nanocoated mesh surfaces.

Swallowing disorder has been becoming a serious issue with increasing in elderly people. Disorder sometimes appears with an decrease in saliva, because saliva has an important role in lubrication over the oral cavity and throat. Though the structure of biological mucosa has been studied physiologically, there are only few studies that examined the influence of its micro structure on fluid lubrication. Therefore, we investigated the friction characteristics by reproducing the micro structure of oral cavity and pharynx. As an example of the oral cavity mucous membrane, the tongue of a pig was subjected to observation by microscope and laser surface shape and roughness measuring machine. As a result, roughness properties of a pig tongue differed from root part to tip part, and it was confirmed that hemispherical protrusions were observed on the tip part by irregular arrangement. An imitation tongue was produced using a high-precision 3D printer. Furthermore, the concentration of thickener was determined from the measurement of the viscous characteristic by the rotational viscometer to have the same viscosity as that of saliva. We measured friction coefficients on the imitation tongue lubricated by artificial saliva. The friction coefficients were changed depending on the lubrication condition and the moving speed.

Cells can efficiently migrate by adopting a spatially asymmetric arrangement of intercellular organelles and molecules. From past researches, it is expected that cell migration and positions of nucleus, microtubules and centrosomes are closely related. In this study, therefore, the distribution of intercellular organelles in HeLa cells was observed under confinement of cell shape by micropatterning using photoactivatable culture substrate. The pattern shape was set to be a triangle with a ratio of base to height of 1: 2 and the pattern area was 625 μm² and 1225 μm². The nucleus, microtubules and centrosome were fluorescently stained and observed using an epifluorescence microscope and a confocal laser scanning microscope. As a result, when the pattern area was 625 μm², the position of the nucleus was the center of the cell, whereas when 1225 μm2, it became close to the cell edge. However, there was no significant difference in the height of the centrosome due to the difference in pattern size.

For the discrimination of living and dead yeast cell, visualization and quantification of dead cell ratio Φ_d in the microchannel are performed based on electrical impedance tomography (EIT). Based on the dead cell indicator, Ψ_d defined as the ratio of imaginary part of impedance between different Φ_d distribution in microchannel is reconstructed by the algorithm of electrical impedance tomography. The reconstructed images shows the good performance regarding quantification of Φ_d within 28.4 % in error rate.

For cell discrimination of cancerous cell, diffusibility α is proposed based on the Nernst-Planck equation by Electrochemical Impedance Spectroscopy. Diffusibility α is calculated by the Nernst-Planck equation, and it means ion transfer rate though the cell membrane. The effect of osmotic concentration on α is studied by changing the sucrose concentration with measuring the suspension of Medical Research Council cell strain 5. It shows that the smaller the osmotic concentration, the larger the α, and the distribution of α is clear at the same osmotic concentration.

We observed the motion of metal nanoparticles in ionic liquid under nonuniform AC electric field. We prepared gold nanoparticles in ionic liquid by transferring gold nanoparticles in citrate buffer to 1-butyl-3-methylimidazolium hexafluorophosphate, and directly observed the behavior of nanoparticles by a high-speed and high-magnification microscope. In this observation, the prepared gold nanoparticle dispersion was dropped on a 25-μm-wide electrodes with 10-μm-wide gap and an AC voltage was applied to the electrodes. As a result, nanoparticles moved towards the center of the gap of electrodes on the electrode surface, and moved away from the center of the gap above the surface. Moreover, the velocity of nanoparticles on the electrode surface increased as the applied voltage increased.

Recently, in the field of regenerative tissue engineering, huge amount of cells are needed for developping new organs and tissues. However, during cell cultivation, cells sometimes show degeneration or change their original characters so that it is needed to separate those cells from original cells. Although fluorescent labeling and magnetic labeling of cells have been used for cell separation, invasive label-free methods are required from the point of view of cell damage. Therefore, our aim is to develop a high-efficiency label-free cell separation system based on the difference in electrical characteristics of cells. In this study, for its first step, an attempt was made to distinguish different type of cells by measuring their electrical properties.

Mechanical cleavage using a serrated scribing wheel is commonly used as glass separation methods in various industrial fields. This method has a lot of advantages such as high production quality and efficiency. However, the crack generation and propagation behaviors, especially the effect of scribing speed on these behaviors, is not fully understood. At first, we observed the crack generation behavior under a static load condition using a high-speed camera. As a result, it was found that some cracks generated in sequence as the loading time increased. Then, the crack generation and propagation behaviors in different scribing speeds were observed. We found that the crack propagation rates were different depending on the scribing speed. When the scribing speed was 100 mm/s, the crack propagated, stopped temporarily, and then developed again during scribing. In contrast, the continuous propagation was observed except for 0.1 second after the wheel passed at 5 mm/s of scribing speed. This difference was likely due to the difference of contact time between wheel teeth and glass surface, which was inversely proportional to the scribing speed. In addition, the indentation depth formed at 100 mm/s was 8 % shallower than that at 5 mm/s. It means that the contact time affects the plastically deformed volume which changes crack propagation rate.

Spheroids means clusters of cells. Since it has a function close to that in vivo, attention is increasing among cell therapy, pharmacokinetic observation. However, when the spheroid becomes over growth, there are problems such that cells in center dies due to deficiency of nutrition and oxygen, so it is necessary to scale cells up to an appropriate size. In this study, we focused on the technology of a rotating wall vessel bioreactor, which is a culturing devise that reproduces microgravity condition by buoyancy generated by rotating a cylindrical container on the horizontal axis. As a result of this experiment, we found advantage of using rotating wall vessel bioreactor composed of two liquids.

Compulsive sedimentation of soil particles using coagulant is one of the solution for long-term turbid water in dams that has a bad effect on the environment of downstream rivers. We utilized allophane as a coagulant. The purpose of this study is to develop an atomization and transportation technique for allophane using the microbubble generator with a Venturi tube. Detailed visualization of atomization behavior of allophane in internal flow of the tube was carried out and the diameter distribution of allophane after passing through the tube was measured. As a result, it was confirmed that allophane was atomized depending on the liquid flow rate in the tube. In addition, the turbidity of water was decreased when allophane after passing through the tube was thrown into the turbid water. In transportation experiment of allophane, it was found that allophane was transported greatest under conditions of microbubble generation. Furthermore, we measured zeta potential of particles, and tried to reveal the mechanisms of turbid water treatment and allophane transportation with considering the interaction of zeta potential between particles and bubbles.

Recently, plating technology has been used widely in industry. Before being plated, the component must go through a series of cleaning progress to ensure the quality of plating. Degreasing is one of the cleaning progress especially for organic compound like cutting oil used while processing. Currently, organic solvent and alkali aqueous solution are used extensively in degreasing process, which has high cost and severe environmental impacts because of the sewage disposal. Therefore, cheaper and more ecofriendly degreasing technology has been desired. Owing to strong acidification power and self-decomposing power, ozone micro-bubbles generated by a Venturi tube was proposed. The purpose of this study is to research the property of ozone micro-bubbles and improve the cleaning mechanism. In this study, the bubble diameters are measured and compared at inlet and outlet of a straight tube and the Venturi tube. Bubbles are detected by visual observation and measured by using image processing. Compared with the straight tube, the Venturi tube generates much smaller bubbles, whose diameters are approximately 100 ~ 120 μm. By titration with Kalim lodide, ozone water concentration and ozone gas concentration are measured at the same condition. Ozone gas is well dissolved by using the Venturi tube. Also, Cuprum test plates applied with cutting oil are washed by ozone micro-bubbles. It has been confirmed that Venturi tube has much better washing ability for oil.

In an automobile engine, bubbles are generated due to rotating gears which drag gas phase into engine oil. That raises void fraction of the engine oil, and it causes decreasing performance of the engine oil in lubricating, cooling and pressure transmission. Although it is required to reduce void fraction and establish a defoaming technique, the processes of bubble generation have not been clarified. One of the reasons is difficulty to measure void fraction and other physical parameters in oil flow using a real engine due to its complexity of the flow. Therefore, influence of rotating speed, number of teeth, and kinematic viscosity of test fluid on bubble generation behavior is not grasped in detail. The motivation of this research is to understand the mechanism of the bubble generation behavior around the rotating body. We performed visualization experiments on simulate oil flow around a rotating body and measured bubble diameter and bubble number density in each rotating speed, shapes of the rotating body, and kinematic viscosity of test fluids. We clarified the influence of each parameter on bubbles. In particular, as the kinematic viscosity of the test fluid increased, the bubble diameter decreased and the bubble number density increased. Farther more, we discussed the mechanism of bubble generation.

Cavitation is a typical unsteady phenomenon and can be a cause of performance deterioration, severe noise, vibration problems, wing erosion in hydraulic systems. Therefore, much research has been done to suppress cavitation. In this study, to elucidation of choking phenomenon in cavitating flow. numerical calculation for cavitating flow in a two-dimentional orifice was carried out using commercial cord, ANSYS Fluent 19.2. For the calculation, the cavitation model is Schnerr-Sauer model and the turbulence model is SST k-ω. Two type calculations which are the case that the outlet pressure decreases step by step from non-cavitating condition and the case that the pressure fluctuates at the outlet are conducted. As the cavity area increases in the throat of the orifice, the phenomenon that the pressure information of the outlet does not propagate to upstream of the throat is observed. In addition, it has been found that, even when the cavity is small, the pressure fluctuation is not propagated upstream, and the minimum pressure on the center line of the orifice is close to the saturation vapor pressure.

In degassing in various kinds of processes, the floating behaviour of the bubble is important. In this study, the floating phenomenon of single bubble in high viscosity liquid was investigated for the degassing in polymerization or food industry. The terminal floating velocity of the bubble which deformed by the rotational Couette flow was measured under the various conditions of viscosity and a shear rate, and the drag coefficient was calculated. The drag coefficient of a bubble was concluded as the Stokes rule by modifying by the cross-sectional area in a floating direction and the aspect ratio of bubble shape. Furthermore, the correlation equation which calculates the cross-sectional area and an aspect ratio based on a shear rate and liquid viscosity was proposed. The floating velocity of the bubbles in high viscosity liquid can be estimated at ±50% by using these formulas.

In severe accidents of nuclear power plants, radioactive contaminated gases are to be released to out of facilities after a process of passing through a water pool such as a suppression pool of BWRs. When the gases pass through a suppression pool, the radioactive aerosols are expected to be trapped in the pool. This decontamination effect is called “pool scrubbing”. Pool scrubbing is considered to have a great decontamination effect. In the severe accident analysis code called MELCOR, the decontamination factor of pool scrubbing is calculated under the gas-liquid two-phase flow model which has some assumptions. But the validity of this model is not sufficiently confirmed. Therefore, the assessment of the flow model in MELCOR is necessary for the proper nuclear regulation. In this study, the flow model was evaluated by the detailed measurements of flow in a test water tank. The flow structures of air jet and air-steam mixture jet were injected to the tank and measured by a wire mesh sensor. The void fraction data obtained by the WMS was converted to the bubble size data. The bubble size data was processed with Gaussian Mixture Model. As a results, it was confirmed that some differences of the bubble size occurred by the presence of steam and subcooling temperature.

Acoustic levitation method is one of objects levitation methods. By levitation the object, it is possible to solve problems such as contamination by container wall surface and loss of chemicals. Therefore, the acoustic levitation method is expected to be applied in various fields such as pharmaceutical science, analytical chemistry, biotechnology. In such fields, a technique for mixing drug is necessary. Watanabe et al. (2018) developed and realized multiple droplets to coalesce into a single droplet and mix it up efficiently using focused ultrasonic wave. It was found that mixing was promoted when the mixed levitated droplets were vibrated by the interfacial oscillation of the 6th mode. The internal flow structure of levitated droplets driven by the oscillation of the applied mode was suggested to be depend on a mixing speed. For the in-depth discussion, it is necessary to elucidate the interaction between an interfacial oscillation and internal flow structure of an acoustically levitated droplet. The purpose of this study is to elucidate the internal flow structure of levitated droplet excited from 3rd to 7th order mode. This paper discusses PIV measurement results of droplets excited by 3rd to 7th order modes using focused ultrasonic wave.

Conventional numerical models of one dimensional flow in pipes employ spatially homogeneous property of fluids, such as density, velocity, and void-fraction. In the case of handling of several liquids separated by air, it is important to use two-phase flow models which have spatially inhomogeneous fluid properties. In order to numerically analyze unsteady several liquid flows in pipes which are separated by air, we propose a calculational model which traces liquid-air surfaces in the pipes. One dimensional fluid equations are solved with finite difference method in our model. In order to evaluate the accuracy of the numerical model, we operated pressure measurement in the channel. We compared pressure amplitude and period of analyzed and experimental pressure histories in unsteady flow.

This paper describes the development of a high-speed, high-resolution photographing method for capturing fuel injection process. We achieved higher speed, 9,600fps, and resolution, 1,920x1,080, even using a consumer camera with specifications of 960fps, HD resolution. By utilizing the phase-shift photographing, this method enables taking the high-speed, high-resolution movies. In this paper, we develop our proposed photographing system and then compared its specifications with those of an industrial high-speed camera. Although some issues are left, we confirmed our proposed system properly worked just as our intended.

Hyperloop is a next-generation transportation system plan that is currently being developed which is a railroad running in a tube with reduced pressure. In this research, we aim to understand the behavior of the capsule and to investigate the running stability by numerical analysis of the flow field inside the Hyperloop tube. In this study, the tube is moved at high speed in numerical calculation and the internal flow field is examined. Calculation is performed considering compressibility in non-steady computation. In addition, each parameter was calculated from the relational expression of the shock wave whose Mach number was changed and given as a condition. In the process of calculation, we changed the total pressure applied and verified in which condition shock waves occur in the tube. Also, we investigated the effects on the capsule due to the changed Mach number and the change in the speed, and made it a basic research to examine the running stability of the Hyperloop.

As a device for fluid, an electro fluidic device has attracted attention. The purpose of this study is to develop flat fluid control devises of CD-PA (Corona Discharge - Plasma Actuator) which has very simple structure and versatility. By PIV (Particle Image Velocimetry), the flow field of the jet with a cathode of needle and an anode of flat plate was examined. Experiment was conducted by changing the length of the side of the anode flat. In addition to the experiments, electric field and flow field were numerically analyzed. According to the visualization experiment, the longer the side length of the anode was, the faster flow velocity is obtained, and the more spreading flow was found. From the numerical analysis, the highest electric field has been obtained with the longest side length of the anode. It has been revealed that there is a correlation between induced velocity and electric field.

The aim of this study is to clarify stability of a drone in a narrow space. In this study, behavior of a drone in a narrow duct was investigated. Experiments were carried out using a drone with a size of 223×232×50 mm and a duct with a diameter of 1030 mm. The drone was installed with changing in axial, circumferential and radial positions of the duct. A range in which a drone can stably fly in a duct was examined and shown as a map. A lot of vibration patterns of a drone were investigated in some points, some of them vibrates strongly and the other points vibrates weaker than those points. With respect to the radial direction of the duct, the closer the center, the more stable the hovering of the drones. The drone was relatively unstable on the lower side compared to the upper side of the duct.

Hydrothermal wave (HTW) instabilities in thermocapillary convection are known to produce undesirable effects when they occur during the float-zone crystal-growth process. Suppression of the hydrothermal-wave instability was demonstrated through the sensing temperature perturbations in a liquid layer and the heating locally periodic perturbations along lines parallel to the crests HTW in the layer. We investigated effect of the vertical location of heating zone on the suppression of the temperature oscillation.

We visualized flow field on an airfoil to investigate influence of residual turbulence intensity on separated flow on the airfoil. The residual turbulence intensity in the main stream was increased by acoustic excitation. Experimental condition was Re = 30,000 and the flow field on an airfoil was visualized by the smoke wire method. By result of the flow visualization on the airfoil, we find differences in flow state of separated region on the airfoil by changing of turbulence intensity. Fluctuating region in the separated shear layer was moved toward leading edge of the airfoil below α = 10 degrees. On the other hand, suppression of extensive separation from the leading edge was confirmed over α = 10 degrees. It is suggested that applying of small disturbances make instability of the separated shear layer amplify effectively, it develops turbulence transition and changes flow state on the airfoil.

In this study, internal structures and strength improvement of 3D-printed continuous carbon fiber reinforced thermoplastic (CFRTP) laminates were investigated. From some preliminary experiments, stress-strain curves and cross-sectional optical microscope images for unidirectional CFRTP laminates were successfully obtained, and then discussed towards higher mechanical properties.

In this study, we attempted to directly mold mode I fracture toughness specimens of continuous carbon fiber reinforced thermoplastic (CFRTP) laminate using FDM type 3D printer (MarkTwo). Then, the DCB test was carried out to evaluate the interlaminar fracture toughness. In addition, the state of the material near the crack tip was observed by X-ray CT imaging and scanning electron microscope (SEM). Furthermore, we conducted FEM analysis and compared with the experimental results, we considered the mechanism of toughness development of this material. The result of the DCB test showed the mode I fracture toughness G=2.07[kJ/m²] in the crack growth process. In X - ray CT imaging results, it was found that a part of the interlaminar detachment of the main crack plane occurred in different layers. Also, many voids were observed. In the SEM observation results, cracks were transferred to several layers, fiber breakage, and separation between fibers and resin were observed. In addition, a fracture surface like a stretched resin was observed, and it was found that it was broken in ductile way. In the FEM analysis results, the analysis value and the experimental value were almost in agreement. However, when the crack length exceeds 20 mm, the experimental value became smaller than the analysis value.

In this study, for the purpose of monitoring distortions and structural health monitoring of the 3D printed products, strain gauges were embedded into 3D printed continuous carbon fiber reinforced plastics (CFRP) during forming by MarkTwo. After that, tensile test is performed, and strain is monitored. As a result, thermal strain distortions were monitored. In addition, a tensile test was carried out using embedded strain gauges and young's modulus that was EL=62.8GPa was obtained.

A partially bendable rigid plate, i.e. a rigid plate with a hinge section, was fabricated using a dual-head three-dimensional printer of fused deposition modeling. The rigid plate section was printed by a Polylactic acid and the hinge section was printed by a thermoplastic elastomer. An anchor shape was designed for the hinge section to prevent debonding of the hinge section from the rigid plate section during bending deformation. Cyclic bending test of the printed partially bendable rigid plate was performed. No significant damage was developed in the hinge section by the cyclic bending up to 100 cycles. The experimental results showed successful one process fabrication technique for a durable partially bendable rigid plate.

Composites including CFRP (Carbon Fiber Reinforced Plastics) have become common. However, the present design of structure is based on metal-material and can not make use of characteristic of CFRP. In this study, we designed curvilinearly skin/stiffener structure by genetic algorithm(GA) optimization for maximization of buckling load. Furthermore, we manufactured test pieces of optimized shape using 3D printer. Through manufacturing optimized shape, we aim for optimized design with higher precision.

Currently, 3D printing technology has attracted much attention as new molding methods for carbon fiber reinforced thermoplastics (CFRTP). The purpose of this study is to investigate in situ resin impregnation during 3D printing of CFRTP. The specimen was manufactured by fused deposition molding (FDM) using carbon fiber yarn and polylactic acid (PLA) filament. Tensile tests were conducted on the molded specimens in order to investigate the effect of process parameters during 3D printing on mechanical properties. As a result, we recommend the modeling temperature T=220°C, print speed v=100 mm/min and filament extrusion speed f=18 mm/min for the PLA composites.

Vacuum-assisted Resin Transfer Molding (VaRTM) process consists of thermosetting resin impregnation to fiber preform and is one of the cost effective way for manufacturing composites. Permeability defined in Darcy’s law corresponds with flowability of matrix resin into fiber preform and is the key parameter in VaRTM process. There are many factors to affect the measurement of permeability. In this paper, the main purpose is to reduce experimental scatter in the permeability measurement by controlling preform nesting conditions. Nesting means the phase shift of fabric weave in adjacent fabrics and affects the distance between fiber yarns, the shape of fiber yarn and fiber volume fraction. Permeability was measured in unsaturated unidirectional flow with epoxy resin as test fluid. Simultaneous measurements were conducted in addition to the single to cancel the difference in epoxy resin conditions. Most of the obtained permeability were distributed in the range of 0.6-0.7×10^-11 m². Experimental scatter in the case of controlling nesting was lower than that in non-controlling.

VaRTM is a method in which resin is injected and impregnated by vacuum pressure in a reinforced fiber substrate vacuum-packed with a film or the like, and the product can be obtained relatively easily and at low cost than the autoclave. On the other hand, impregnation failure of the resin into the base material occurs, which causes problems of low dimensional accuracy and mechanical properties. Therefore, it is necessary to evaluate the penetration coefficient which is an index showing the impregnation behavior. Therefore, in this research, experimental equipment, procedures, and evaluation method were examined in order to reduce variation in penetration coefficient measurement. In addition, in order to consider the influence of curing of the resin, the measurement result of viscosity change of the resin was applied to the value of the permeation coefficient. Results It is conceivable that nesting is involved in the occurrence of race tracking and the variation in the value of the permeability coefficient.

Accurate measurements for mechanical properties of unidirectional carbon fiber reinforced plastics (CFRP) are difficult, because many destruction of unidirectional CFRP specimen occurs at the edge or inside of tab parts. Bonding properties between CFRP and tabs was focused, effect of adhesion on hardener for epoxy resin and materials of tabs was investigated. Denature polyamine and polymercaptan were used as hardener for epoxy resin. And, glass fiber reinforced plastics (GFRP), aluminum, poly(methyl methacrylate) (PMMA) and stainless steel (SUS) were bonded as materials of tabs. Adhesive strength as bonding properties was measured in tensile lap-shear strength test for adhesive joint specimens using those hardener and base materials. As results, it was shown that adhesive strength at specimen used denature polyamine was higher than that used polymercaptan. The results of observation on failure surface were suggested that different of those adhesive strengths depends on interfacial strength between adhesive and base material. On the other hands, the comparison of base materials was shown that adhesive strength of CFRP/PMMA specimen was the lowest 3.59 MPa and adhesive strength of CFRP/SUS specimen was the highest 17.1 MPa. The results of observation on failure surface were suggested that adhesive strengths depend on interfacial strength between adhesive and base material. However, for adhesive stress over than 13 MPa, adhesive strength might depend on interfacial strength between carbon fiber and matrix inside CFRP base materials.

It is important to control the growth of fatigue cracks for a long time. These cracks usually occur from the stress concentration at the corner and the heat stress area by the welding heat and so on. And these are growing due to the vibration. When a crack length reaches the limit, it is called an unstable fracture state. Then, it cannot be controlled. The aims of this study are to relax the stress of stress concentrated part and to prolong crack growth. As a basic research, we confirm to give local force using the piezoelectric actuator. The results of the experiments show that it was able to give local force using the piezoelectric actuator. Also, larger compressive force was obtained by sticking in a straight line rather than tilting and pasting when sandwiching and applying the piezoelectric actuator.

The structures and the machinery which support social foundation possess many splices. Especially, bolts are the most often used as fastening elements. However, these bolts loosen or break by external forces which act on the fastening parts. As a result, that they may lead to destruction of the structures and the machinery. As the measures to prevent such accidents, periodic inspections are carried out. However, the check by the workers includes problems of time, labor and costs, and the inspection precision is left with doubts. In this research, we have developed a sensor which can monitor the fastening condition based on the change of the shear load applied to the bolts using a piezo-cable. Piezo-cables that we focused on are piezoelectric elements having a piezoelectric effect that generates a voltage in response to external force. It is possible to construct a system of self-check function and to prevent accidents. As a results of monitoring tests using the Bolt Looseness Sensor, when the bolt is tightened, output voltage from the sensor was low. On the other hand, when the bolt is loosened, output voltage from the sensor was high. From these results, the Bolt Looseness Sensor using the Piezo-cables is expected as the sensor for monitoring of the fastening state, because the output voltage from the sensor greatly changed by the change of the fastening state.

Urethane rubber has high hardness and is often used when it is subjected to compressive load. However, rubber exhibits complex mechanical behavior from the effect of the additive and it is difficult to treat with the rubber property when rubber products are analyzed. Therefore, in this study, a stress relaxation test of urethane rubber was performed with different stroke rates. The experimental method was carried out according to JIS K 6254. The diameter of cylindrical specimen was 29 mm, and the height was 12.5 mm. The specimen was compressed at a constant stroke rate until the stroke is 3.75 mm. and the stroke was fixed for 180 seconds. Then it began to return the stroke to 0 mm at the same stroke rate. This procedure was repeated 2 times. And in consideration of hyperelasticity, viscoelasticity, Mullins effect, gap between specimen and indenter, appropriate material parameters were searched by using the finite element method and the Nelder-Mead method. As a result of the analysis, values of material parameter which numerical result approached to experimental result were obtained. There was a tendency that as one of viscoelasticity parameters monotonously decreased. And one of hyperelasticity parameters increased when another parameter decreased.

In recent years, selective laser melting (SLM) has attracted attention in manufacturing field. SLM is a process in which metallic powder is melted selectively by laser irradiation. It allows the fabrication of metal objects; thus, it is commonly applied to aerospace and medical fields. Moreover, complex 3D CAD data can be fabricated directly by SLM process, therefore weight reduction of fabricated parts are expected. Recently, lattice structure and topology optimization are used along with SLM. However, designing lattice structure takes a long time because optimizing the structure is needed. In this study, the simple weight reduction method which takes less time was investigated. The weight reduction samples fabricated by changing laser conditions to generate voids and by designing samples with through holes was considered. Density and tensile strength of these samples were measured. As a result, the weight reduction samples fabricated by designing through holes was higher tensile strength than the weight reduction samples fabricated by changing laser conditions.

Selective laser melting (SLM) is a processing method of fabricating components by repeating the process with layering powder bed and melting them selectively by a laser beam. Any material meltable by a laser beam can be fabricated via SLM even if it is a difficult-to-cut material such as Inconel718, so that SLM is getting to be applied in various manufacturing industrial fields. It is widely known that the appropriate heat treatment improves mechanical properties and many previous researches have reported that mechanical properties of SLM components are improved by heat treatment. However, the optimal heat treatment condition for SLM components has not been elucidated and the heat treatment standard for SLM components is not standardized. In this study, we conducted various heat treatments and tensile tests on IN718 SLM specimen fabricated by applying different processing conditions and investigated the proper heat treatment for the SLM.

Selective laser melting (SLM) is attracted much attention as a new manufacturing process because it is suitable for trial production and manufacturing of complex 3D micro-structure. However, the processing parameter is different for each material, and the material used in SLM is limited. Recently, copper alloys are attracting attention as new materials for SLM because of their excellent electrical and thermal conductivity. It is expected to be applied in a wide range of fields if it becomes possible to use copper alloys in SLM. It is difficult to manufacture parts made of copper alloys for SLM due to high laser reflectivity and high thermal conductivity. The objective of this research is to develop optimal processing parameters of copper alloys in SLM. The effect of processing parameters on the mechanical properties of copper alloys were discussed in this report.

Electrical Discharge Machining (EDM) is a process to remove a portion of material by electrical discharge in insulating working fluid. In previous study, machining characteristics changed in EDM with micro-bubbles. It is inferred that this machining result was caused by various factor (e.g. the types of machining fluid, injection of machining fluid and characteristics of microbubble). In addition, it found that surface roughness differs depending on the workpiece even under the same discharge condition. In this study, Oil machining, EDM with micro-bubble and oil injection machining were compared. We considered the machining removal rate and surface properties. The machining removal rate decreased due to microbubbles and oil injection. It was found that number of discharge decreased due to working fluid injection. It also varies due to material properties. Surface roughness Ra did not change with micro-bubble or oil injection. However, they have different values depending on physical properties of the material. On the other hand, skewness was considered to be influenced by micro-bubble.

The micro tubular parts produced with micro tube hydroforming (MTHF) process have not still been successfully applied in the industry due to the difficulty of developing the MTHF tools as well as the solving the friction problem. In this study, to realize a hydroforming process of long microtube, a new concept of reducing friction between tube and die was proposed with considering the elastic deformation of the die. To study the influence of friction on the deformation behavior of lomg micro tube and the elastic deformation behavior of the die opening during the micro hydroforming process, numerical simulation of the micro hydroforming process of the cross-shape part was carried out. The results showed that friction has a significant effect on the deformation behavior of the long tube during the MTHF process. For a long microtube, it is validated that a new die structure with allowable local die-opening deformation promotes material flow due to reducing the friction resistant.

Elastomer-based incremental sheet forming method is a newly-developed manufacturing process, in which a blank sheet is indirectly deformed by rounded-bar tool and the help of an elastomer plate which is placed on the other side of the metal sheet. On traditional incremental sheet forming method, material displacement is regulated along the straight projection line that is perpendicular to the original material plane prior to the deformation. Therefore, products with vertical or overhunged segment cannot be basically produced on the traditional method. This study aimed developing a novel forming method based on the elastomer-based incremental sheet forming method to enable forming of curved product. In order to evaluate the effectiveness of the proposed method, we formed the curved products. The curved products were successfully formed. Forming of spatially curved products was achieved by using the proposed method. Then, the plane strain was measured on the product.

To improve the accuracy of lunar laser-ranging (LLR), we are currently investigating a new LLR system. The new LLR system requires a corner cube mirror (CCM) with a large aperture. Owing to the size of its aperture, the CCM is difficult to produce by previous fabrication techniques. Therefore, for the production of CCM, we have proposed a process chain of shaping of its optical surface, in which polishing and ion beams figuring (IBF) are used for key fabrication techniques. In this paper, we introduce the present status of the development of polishing and IBF techniques for the process of the CCM. For the polishing step, we proposed a new method using a plate spring and developed a polishing machine to polish optical corners, which has a potential for polishing the CCM with high accuracy. IBF allows the machining of surfaces with high atomic-level accuracy because the removal progresses on the basis of the sputtering of atoms. However, to our knowledge, IBF has not yet been used for the machining of three intersecting surfaces, such as the optical surfaces of the new CCM. Thus, the application of IBF to the fabrication process of the CCM was examined by investigating the irradiation of ion beams to two intersecting plates.

We investigated the catalytic effect in the graphitization of diamond for nanoprocessing method. Experimental procedure was as follows: First, metal catalysts were deposited on diamond. Second, the sample was heated at 750°C for one hour. Finally, the metal catalysts were removed. By this method, selective etching with the catalysts was expected. The modification from diamond to graphite was investigated by Raman spectroscopy. As a result, graphite was detected in the diamond deposited with Ni, Fe and, Pt. On the other hand, graphite was not detected that deposited with Au and Ag. In addition, the surface of diamond deposited with Ni was heated in atmosphere formed the anisotropic etching pit consisting of (111) plane.