Plastic injection molding (PIM) is one of the most important manufacturing processes for producing plastic products. The process parameters in the PIM, such as mold temperature, melt temperature, and injection pressure affect the product quality and the manufacturing cost. In general, these are determined by a trial-and-error method, but computer-aided engineering coupled with optimization technique is recognized as one of the useful tools available. Numerical simulation in the PIM is so numerically intensive that response surface approach is valid for determining the optimal process parameters. In particular, a sequential approximate optimization (SAO) that response surface is constructed and optimized repeatedly is valid to find the optimal process parameters with a small number of simulation runs. In this paper, a cup-type plastic product is considered. The volume shrinkage is one of the major defects for dimension accuracy. In addition, it is important to produce the product with a minimum clamping force for the productivity. Short shot that the melt plastic is not filled into the die cavity is a serious defect, and this is handled as the design constraint. Thus, a multi-objective optimization problem is formulated. The pareto-frontier is identified by using the SAO with the radial basis function network. The difference of pareto-frontier with and without the injection and packing time is discussed. It is clear from the numerical result that the injection and packing time have influence on the product quality.

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Independence support robots using multi joint manipulators are thriving in the field of welfare. Keyboards or joysticks are generally used in the remote operation of the multi joint manipulators. The posture of the multi joint manipulators can be ordered by the angle of the joystick or preconfigured key assignment. These control systems have a problem, however, that the number of operable joints is limited to the number of joystick axes or keyboard buttons. In this study, we propose a remote control system for the multi joint manipulator using touch panel and gyroscope sensor. We call the system TGC (Touch Gyro Control). Miniaturization and performance increase are in progress to various sensors such as gyroscope and touch panel with the development of MEMS technology in recent years. In addition, these sensors have spread rapidly in our living environment. In this study, we use touch panel and gyroscope sensor mounted on a smartphone. The TGC system can control rotational movement of the manipulator using the orientation of the smartphone, translational movement in the horizontal plane using the drag operation of the touch panel display and translational movement in the vertical plane using up and down motion of the arm which is gripping the smartphone. For the quantitative evaluation, we experimented with 3D pointing tasks using the TGC and compared to the conventional method of button-type control. The result of the experiment indicated that the TGC could point faster than conventional button-type method. In addition, we also experimented with the task that grip and transfer screws into a box using 6-DOF manipulator which is controlled by above two methods. The result of this experiment also showed the advantage of the TGC. The usefulness of the TGC for the operation of the multi joint manipulator is verified in this research.

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Methods such as the Predicted Mean Vote and Standard New Effective Temperature were developed to evaluate thermal comfort. However, radiation and convection of heat due to factors such as sunlight or air cycle are strong in indoor environments. Moreover, the thermal environment in such indoor environment is non-uniform and locally inhomogeneous, which makes evaluation thermal comfort difficult. We aim to evaluate the local thermal environment by analyzing brain activity. The final goal is to develop an air conditioning control system in non-uniform and locally inhomogeneous thermal environment by brain activity. In this paper, we describe analysis of brain activity during local cold stimulation. We measured oxyhemoglobin (oxyHb) levels in the prefrontal cortex and the primary somatosensory cortex while subjects touched aluminum plates that were cooled or heated to different temperatures. The results show that oxyHb changes in the prefrontal cortex vary according to the temperature of the aluminum plates.

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The “buffet” which is the shock wave vibration on the wing at transonic speed has influence to the aerodynamic performance of the civil transport. It is significant because the wing cannot maintain its aerodynamic performance and it is also led to the stall. Therefore, several researches on the suppression of the buffet are carried out. A Vortex Generator (VG) is one of the way which can improve to the transonic buffet. It is simple device and widely applied to the commercial airplane. Conventionally, VGs are installed along the wing span. However, they increase the friction and the instruction drag. Thus, the number of VGs should not be beyond the minimum necessary. Another problem is that it is still expensive for the computational fluid dynamics to simulate the small size vortex accurately. Therefore, the optimization procedure of the VGs installation is developed with directly combining the wind tunnel evaluation result. To reduce the number of experimentations, the surrogate model based GA exploration is employed. The design objective is to maintain the linearity of the variation lift with changing angle of attack (lift curve), because the stall is appeared if the curvature of the lift curves become smaller. Eight initial designs are evaluated and five design samples are acquired. As this result, optimum samples can be explored with reducing the number of the experiment. Several samples successfully prevent the stall without increasing the drag. In addition, the design knowledge can be obtained regarding the optimum VG’s layout by visualization.

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Vibration suppression is one of the most important problems in the design and operation of space structures. Due to limited launch capabilities, such structures need to be extremely light-weight although some structures succumb to vibrations because of their low structural stiffness. Moreover, vibrational energy is hard to disperse in the vacuum of space, in contrast to ground environments. These problems can be overcome by vibration control schemes.Vibration control schemes can be categorized into three types: active, passive and semi-active. The semi-active vibration control (SAVC), dynamically changes some property of the structure according to feedback from the state, without adding extra energy. SAVC systems are usually able to achieve higher performance than the passive vibration control schemes without the disadvantages of the active vibration control systems. In this study, optimal piezo actuator layout is solved by the introduction of Shock Response Spectrum (SRS) constraint which evaluates vibration and a shock.

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Car navigation systems have recently become a popular assist system for automobiles. On the other hand, lack of dedicated motorcycle navigation system is still an issue. This is because currently provided navigation system utilizable for motorcycle has difficulties for riders to obtain information while driving. Recent research propose of using the head-up display technology is considered to solve this issue. Although, topics about the amount of information to provide using the head-up display has not yet been discussed. Since providing too much information distracts driving behaviors, amount of information control is required to prevent inattentive driving behaviors. To evaluate the preferable amount of information, we conducted an experiment using the immersive motorcycle simulator integrated with a head-up display. The experiment measured motorcycle riders' viewpoint movements using the eye-mark recorder to observe the duration spent against the information provided using the head-up display. Through the experiment, we presented different length of Japanese syllabary characters (Hiragana) on the head-up display to 10 subjects. Experiments results indicate presenting 5 Japanese syllabary characters is the preferable amount of information to the motorcycle rider while driving. Applying information theories, we conclude that the preferable information transmission rate is approximately 16 bits per seconds.

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Adequate optimization formulation and algorithm choices are essential for successful optimal design of a multi-disciplinary system. Details of such process remain with the realm of tacit experimental knowledge and skills of engineers. The future goal of our research is to build a descriptive management method that facilitates explicit description of experimental knowledge of engineers. This paper aims at clarifying an acquisition process of experimental knowledge in optimal design of a multi-disciplinary system. An experimental design optimization of a desiccant air system is performed to capture the process. Some typical process patterns are formalized based on the analysis of the captured process. This paper also discusses a vision for the descriptive management.

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In this study, an axial force sensor was developed and evaluated for a screw bolt using optical fiber grating (FBG: fiber Bragg grating). This sensor has high tolerance to electromagnetic noise. Furthermore, it has a characteristic long-distance signal transmission ability because it was made using optical fiber. This washer type sensor forms a circular projection because the stress distribution in the sensor is obtained only proportional to the axial force of the screw bolt. The axial force sensor was experimentally developed for an M10 screw bolt. According to test results, the reflection wavelength shift was proportional to the axial force, implying that this sensor has excellent characteristics.

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In this study, capability and reliability of advanced repairing technology based upon thermal spraying technique are examined. In order to achieve this purpose, the damage evolution progressed in the repaired part is clarified through continuous observation under tensile loading, and residual stress and the critical strain up to the delamination of the repaired part were identified. As the results, the continuous observation revealed that crack was initiated and propagated along the interface in the repaired part during a tensile loading, which brought about a dog-legged shape deformation in the whole specimen. It was recognized that the repaired part was peeled off as the repairing length (L) became long. From relationship between the repairing length normalized by the depth (L/h) and residual stress and the critical strain on double plot style, it was found that residual stress increases to compressive side with the normalized repaired length, but the amount of residual stress (order in 50MPa) was very low in comparison with one (order in 500MPa) known in a welding technique. The critical strain also increased with the length, which means that it is desirable to remove a large region from the damage part in the structure. It can be claimed that APS repairing technique has great capability in place of a traditional welding approach.

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Pure bending fatigue tests were conducted with single-sided fillet welded T-joint specimens. Two load conditions, which were given the tensile and compressive stresses in the weld toe, were applied, and fatigue strengths at 2×10⁶ cycles were determined. Next, we conducted crack analyses simulating the fatigue tests by FEM. In the analyses, initial toe crack of 0.2 mm and root gap were modeled by slit, and opening displacements of the slit tip were calculated. From these displacements, stress intensity factors acting on the maximum principal stress plane were calculated. By comparing fatigue tests and crack analyses, fracture criteria for pure bending were estimated. These criteria were extended to the conditions in which tension and bending load were applied simultaneously, and fracture limit lines based on hot spot stress were calculated in each root gap and weld toe. By using these limit lines and material based strength, the fracture design maps that can be evaluated the fatigue strength of both root gap and weld toe at the same time are proposed.

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Residual stress that is mainly caused by heat treatment is one of the important factors in mechanical products such as internal combustion engines, since it affects the maintenance of peak performance and operational durability in competitive scenarios. In this paper, a phase transformation analysis method, in which volume fraction of 4 phases (Ferrite, Pearlite, Bainite and Martensite) during heat treatment process can be individually taken into account, is constructed for the prediction of residual stress caused by heat treatment such as induction hardening. First, phase transformation problem, considering the history of time and temperature, is formulated with the volume fraction of 4 phases, based on the idea of the autocatalysis nucleation. Next, material parameters of heat-treated steel SCM440 and non-heat-treated steel S50C in the evolution equations are identified by comparing the model with the measured and literature data. Finally, the proposed method is applied to SCM440 and S50C under the condition of induction hardening, in which different grain size is considered, and the validity of the proposed method is confirmed.

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The objective of this study is to evaluate crack growth behavior under cyclic tensile loading considering crack closure effect. Crack growth behavior under cyclic tensile loading on a plate with surface crack is tested. Material is 2017 aluminum alloy. Crack growth process is studied by experiment and simulation. Crack growth behavior is analyzed by S-version FEM. In order to predict crack growth behavior in detail, crack closure effect is taken into account. Crack closure effect along surface crack tip under cyclic tensile loading is analyzed by ANSYS. In order to consider crack closure effect, an effective stress range ratio is introduced. An effective stress range ratio is defined by load range during crack opening over load amplitude. It is found that an effective stress range ratio is small near the surface of the specimen. This means crack growth rate is small near the surface of the specimen. Effective stress intensity factor range is calculated by effective stress range ratio. Using this effective stress intensity factor range, crack growth simulation with crack closure effect is performed by S-FEM. Crack shape and number of cycles of the simulation which considering crack closure effect comes close to experiment. And even if the thickness of the specimen is different, the influence of crack closure effect hardly varies.

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The cut surface obtained by blanking has burrs, whose occurrence should be prevented. Push-back blanking is one of the burr free blanking methods. This method was consists of two stages. The first stage is a half-blanking stage, and in the second stage the product is separated from the scrap by pushing the half-blanked material. It is known that the range of successful blanking conditions decreases with decreasing scrap width. In this paper, the effects of constraint of the sheet material on the range of successful blanking conditions and the cut surface are discussed on the basis of the results of an experiment when the scrap width is small. The experiment was carried out using a disk-shaped specimen whose outer peripheral surface was constrained in the first stage. This study clarified the following. The constraint of the specimen in the first stage was effective for increasing the range of successful blanking conditions when the scrap width was small. It is considered that the increase in the range of successful blanking conditions is caused by the decreased the bending deformation and the compressive deformation of the scrap in the second stage from the observation of a cross section of the specimen. The shear droop formed in the half-blanking stage and separating stage was decreased when the specimen was constrained in the first stage.

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Our objective is to analyze both tensional and bending stress of bolted joints under eccentric load. Especially, our analysis is under four combined conditions as described below, (1) embedded bolted joints, (2) thinner clamped plate, (3) large eccentric load, (4) permitting partial separation. Those combined conditions include some difference between ours and previous researches. The partial separation easily occurs at structural interfaces under those combined conditions, and both stresses sharply increase due to the propagation of the separation. That is the reason why it is very important to consider the effect of partial separation. There are many analytical methods based on numerical calculations or FEM analysis, however, there is no numerical calculation method, which is justly applicable under those combined conditions. We apply Faulhaber method proposed in VDI2230 and develop our original method considering the bolt axial loads, which are composed of both bolt's deflection and deflection angle as beam. Numerical calculations on the above-mentioned and experiments and elastic FEM analysis based on three dimensional contact theory were conducted. The results about our method's correlation against experiments and FEM analysis are shown in this report.

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Crack propagation tests of lead-free solder were conducted using center-notched plates under load- and displacement-controlled conditions of cyclic tension-compression. Four waveforms were adopted for tests: pp waveform having fast loading and unloading, cc-h waveform having a hold time under tension and compression, cp-h waveform having a hold time under tension, and pc-h waveform having a hold time under compression. The crack propagation rate was correlated to fatigue and creep components of the J-integral range determined from load-displacement curves. For pp waveforms, the crack propagation rate was expressed as a power function of fatigue J integral range and the relation was identical for load-controlled and displacement-controlled conditions. The creep component due to the hold time greatly accelerated the crack propagation rate when compared at the same values of the fatigue J integral, especially under load-controlled conditions of cc-h and cp-h waveforms. Not much acceleration of crack propagation was observed for displacement-controlled conditions. The creep crack propagation rate was expressed as a power function of the creep J integral range for each case of cp-h and cc-h waveforms. The crack propagation rate for cp-h waveforms is higher than that for cc-h waveforms. As a simple estimate, the apparent J-integral range was evaluated from the area between the loading curve and the straight line connecting maximum and minimum loads in load-displacement relations. The relation between crack propagation rate and apparent J-integral range for symmetrical loading waveforms such as cc-h was only slightly higher than that obtained for pp waveforms, and the relation for unsymmetrical loading waveforms with tensile hold such as cp-h was much higher.

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Creep-fatigue crack propagation tests of lead-free solder were conducted under various loading waveforms. The waveforms adapted in displacement-controlled tests were four triangular waveforms: pp waveform having fast loading-unloading, cc waveform having slow loading-unloading, cp waveform with slow loading followed by fast unloading, and pc waveform with fast loading followed by slow unloading, and three waveforms with hold time: cc-h waveform having a hold time under tension and compression, cp-h waveform having a hold time under tension, and pc-h waveform having a hold time under compression. In load-controlled conditions, three waveforms are adapted: pp, cc-h and cp-h. Microscopic observation using SEM and EBSD was conducted near the crack tip region and on fracture surfaces. Plenty of microcracks were observed near the main crack tip on the surfaces of specimens, while almost all of them disappeared after removing the surface layer of about 0.4mm. On the removed surfaces, microcracks were observed near the main crack tip for unsymmetrical waveforms, cp, pc, cp-h, while no microcracks for symmetrical waveforms, pp, cc, cc-h. The existence of microcracks is responsible for crack acceleration under unsymmetrical waveforms. EBSD observation showed the formation of subgrains within original grains of Sn and eutectic phases near the crack tip, and the grain size decreased with increasing crack propagation rates. The grain average of GROD also decreased with increasing crack propagation rate, while that of KAM was nearly constant without respect to the crack propagation rate. Striations, fragmentation, and intergranular fracture facets are three main features of creep-fatigue fracture surfaces. The features of striations were clear for the cases of pp, cc, pc, while vague for the other cases. The spacing of striations was nearly equal to the crack propagation rate, supporting the linear summation rule of creep and fatigue crack propagation rates. Plenty of intergranular facets were observed for cp, cp-h. Fragmentation was abundant for waveforms including creep contribution.

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The purpose of this study is to propose an effective model to estimate the filling fraction of compacts made from magnesium alloy particles, considering the effects of particle size, temperature and pressure. In order to investigate the influence of the particle size, six kinds of particles were prepared in which the cross sectional area was different. The test particles made from AZ91D were poured into a compression vessel and then a given pressure was applied to the piston of vessel for six hours under constant temperature condition. During the testing, the displacement of piston was measured to evaluate the change of bulk density of compacts, and then the filling fraction was simply calculated by the ratio of bulk density of compacts and density of AZ91D. Test results showed that the filling fraction of the largest particles was lower than that of other particles in the temperature region between 523 K and 623 K. The densification rates of compacts were increased with increase of applied pressure and temperature elevation. The experimental equation of densification rates of compacts was determined to discuss the effects of cross sectional area on densification rate. Determination results showed that the transition point to the steady creep was increased with increase of cross sectional area of particles.

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The strain measurement system using a CMOS inverter oscillator circuit is simple and can be omit an amplifier because a counting device measures frequency changes of circuit voltage output caused by resistance changes of a strain gauge. Moreover, the miniaturization and the creation of a wireless system become possible easily, and this system is an effective method which can be applied to large-scale strain measurement and strain measurement on rotating elements. However, this measuring method may be subject to the influences of temperature properties of elements used in the circuit and an external noise, because the resistance change of a strain gauge is measured directly by the oscillator circuit. In this study, static tensile tests were carried out and the tensile strains were measured by using this measuring method. Through the test results, it has been shown that, by using a dummy gauge in addition to a strain gauge for measurement and taking the difference of both output results, the influences have been deleted and the measurement accuracy has been improved.

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Tendon Force is an integral value of inherent stress associated with inherent strain, which is the root cause of welding-induced longitudinal residual stress, shrinkage and bending distortion. Also, Tendon Force concept is a very useful tool for estimating the weld longitudinal shrinkage and bending distortion in large welded structures based on the elastic finite element solution. Several predictive formulae for Tendon Force have already been proposed on the basis of welding conditions, but a unified understanding of the effect of welding conditions on Tendon Force has not yet been achieved. In this paper, dominant factors influencing Tendon Force in welded structural materials were discussed through the use of theoretical and numerical approach to quantify the effect of welding conditions, such as weld heat input, material properties and dimensions of weld joint, on Tendon Force due to welding. First, numerical investigations on the effect of welding conditions on Tendon Force were systematically performed using FE-analysis. After that, the numerical results obtained were arranged according to thermal elastic-plastic parameter, which was derived from the theory of thermo-mechanical process in welding. Based on the results, it was clarified that a unified evaluation of the effect of welding conditions on Tendon Force could be achieved by means of the thermal elastic-plastic parameter. The usefulness of thermal elastic-plastic parameter was thus verified as the dominant factor influencing Tendon Force due to welding.

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A 1800 MPa class steel bar with an ultrafine elongated grain (UFEG) structure was fabricated by multipass caliber rolling at 500°C. The static three-point bending test was conducted in a temperature range from 100°C to -196°C. The behaviors of crack propagation on the developed steel were studied on the basis of the microstructural features. The conventionally quenched and tempered steel with a martensitic structure showed a catastrophic fracture behavior which fractured with a peak bending load in a temperature range from 23°C to -196°C. The crack propagated directly across the center portion of the test bar. On the other hand, the developed steel exhibited a noncatastrophic fracture behavior with evidence of stepwise load increases beyond the first load drop. The microcrack occurred, from near the notch root, with normal to the loading direction (LD) or with an angle of 45° to the LD, and the crack propagated with many zigzag cracks branching from the zigzag crack along the longitudinal direction of the test bar. The occurrence of such brunching cracks corresponded to the spatial distribution of {100} cleavage planes and boundaries of the elongated grains. Namely, the microstructural damage is not localized but rather is widely distributed over very large dimensions. In the bending load - displacement curve, many load drops appeared, and the bending load did not decrease with an increase in displacement due to two effects: the stress shielding effect associated with the interference of multiple cracks and the effect of the improved plastic deformation associated with grain refinement and texture.

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We examined the stress concentration that would occur at grain boundary triple lines during deformation in two copper tricrystals with [011] tilt boundaries; one was a symmetrical tricrystal with respect to the loading axis and the other was an anti-symmetrical one. In principle, the finite element method can provide solutions with prescribed amount of precision for the anisotropic elasticity problem. It was shown that a close approximation was possible by means of a disclination model in elastically homogeneous material. This disclination model was numerically solved with the finite element method proposed in a previous paper (Hosoya, Kato, Sasaki, Trans. JSME, Vol.80, No.819 (2014 ). It was concluded that the disclination model is appropriate for estimating the stress concentration at the grain boundary triple lines in deformed polycrystals.

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Effect of Laves phase precipitation on the fatigue behavior in JFE 429EX ferritic stainless steel was investigated. When this material is exposed to the temperature range of 700-900°C, the precipitation of Laves phase (Fe₂Nb) occurs, resulting in the embrittlement of material known as Laves phase embrittlement. Axial loading fatigue tests have been conducted in laboratory air and in 3%NaCl solution using a niobium-containing ferritic stainless steel, JFE 429EX, aged at 700, 800 or 900°C. In laboratory air, the fatigue strengths of 700°C-aged specimen were improved by the fine Laves phase precipitation into α-phase. Whereas the fatigue strengths of 800 and 900°C-aged specimens decreased, which was attributed to the coarsening of Laves phase precipitates. On the other hand, in 3%NaCl solution, the fatigue strengths of all aged specimens were lower than those in laboratory air. That was because sensitization took place during aging, that is, the chromium-depleted zones were formed along grain boundaries.

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This work aims at developing a new fan-turbine that operates as a cooling fan at a low vehicle speed and operates as a wind turbine at a high vehicle speed to generate electric power. The present paper reports the influence of a wind turbine on air resistance through a vehicle cooling system. We have developed a method to measure air resistance by using a general-purpose facility and the following results have been provided. The wind turbine operation reduces air resistance through the cooling system and regenerates electric power simultaneously. Furthermore we have confirmed the influence of the wind turbine on air resistance through the vehicle cooling system by using a CFD analysis.

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The model experiment, the numerical calculation and the theoretical analysis are performed to investigate the characteristic of a viscous micropump by using a rotating cylinder in an elbow duct. In the experiment, the low Reynolds flow in the centimeter-scale micropump is realized by using glycerin as working fluid. The flow is visualized by an aluminum powder for Particle Image Velocimetry (PIV) analysis. In the theoretical analysis, the 2D lubrication theory is adopted and the pressure performance formula of the viscous micropump in the elbow duct is proposed. The performance curves derived from the formula agree well with the numerical results. Therefore, the proposed formula can be used for the design of the viscous micropump in the elbow duct. The performance curve, the φ-ΨRe curve, becomes a straight line with a negative slope. In the experimental and numerical results, the two vortices which rotate in the opposite direction of the rotating cylinder are observed. With an increase of the angle of the elbow duct, the pressure dimensionless number at the zero flow coefficient increases and the flow coefficient at the zero pressure coefficient slightly decreases. The pressure performance is degraded at the normalized partition lengths smaller than 0.05.

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Turbulent statistical properties in the outer region are presented for high Reynolds number turbulent pipe flow using LDV (Laser Doppler Velocimetry) measurement. Employing the indicator function for turbulence intensity, the region which has logarithmic behavior is not only observed in second moment but also higher even moments. It is found that power spectrum density distributions in these regions have approximately -1 law profile which mainly consists of LSM (Large Scale Motion) and VLSM (Very Large Scale Motion). However, the spectral dependence on the wall distance is different from based on Attached-Eddy model. We observed that the region where PDFs (Probability Density Function) are approximately invariant against the wall normal distance is enlarged with increasing Reynolds number. And, it is found that this invariant PDF region overlaps with logarithmic profiles of the even order moments. We clarified the relation between logarithmic behaviors in the even order moments and invariance property of PDF against the wall distance. However, in the finite Reynolds number experiment, it is reported that invariance property of PDF is approximately satisfied. And so, we derived the relation between the even moment profiles and invariance of PDF, and verified the relation using experimental results. Finally, we expected that, in the infinite Reynolds number condition, the invariance property of PDF and the logarithmic relations in the even moments are realized.

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This paper describes the expansion of the measurable range of the temperature measurement method using a thermo-chromic liquid crystal. At first, we investigated the relationship between the profile of the spectrum intensity of the scattered light from the surface of the thermo-chromic liquid crystal and the temperature. A halogen light source with an infrared cutoff filter was used as the irradiation light source. Results show that the spectrum intensity of the scattered light increased monotonically with temperature in the range of wavelength shorter than 450nm, and the temperature could be identified by measuring the spectrum intensity of only a single specific narrow-band wavelength. The range of the measurable temperature of the method using this relation was validated using a monochrome-camera and narrow band-path filter of 442nm with FWHN=10nm. It was found that the measurable temperature range became about two times broader than that of conventional methods. In addition, the application of this method to the measurement of the two-dimensional temperature distribution was performed and temperatures with the range wider than that of conventional methods could be measured.

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For the safety design of a Sodium-cooled Fast Reactor, it is strongly required that the molten material which is released from a core region has to be solidified and cooled down in a reactor vessel by breaking up in the sodium coolant during a Core Disruptive Accident. In this paper, in order to investigate the effects of the surface solidification on the fragmentation of a molten jet, the experimental results using a low melting point alloy and water are reported. After the molten jet is injected into water, the fragments are collected from the test section. The shapes of the fragments are investigated, and the mass median diameter of the fragments, which indicates characteristic diameter of the fragments, is measured using sieves. From the results, it is found that fragments with several shapes such as sphere, filament and sheet are generated. The tendency of the mass median diameter of the spherical fragments is close to the Critical Weber number theory. However, the tendency of the mass median diameter of the fragments except the spherical fragments, which are mostly the filament and sheet fragments, is larger than the previous theories such as the Critical Weber number theory and the Kelvin-Helmholtz instability. Then we applied the interfacial instability considering the effects of the surface solidification to the jet system. As a consequence, it is found that the interfacial instability has a possibility of evaluating the tendency of the mass median diameter of the filament and sheet fragment.

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Highly efficient natural gas engines have been widely used in wide range of sectors from industry and transportation. However, because combustion process in gas engines with a pre-chamber is very complicated, it is difficult to experimentally investigate the combustion process including flame propagation from the pre-chamber. In this study, combustion characteristics in the gas engine with a pre-chamber were numerically investigated by using three-dimensional numerical simulation with detailed chemical reactions. Torch flame combustion brings about high temperature and strong turbulence to the main chamber. Combustion processes of the natural gas engine with pre-chamber can be categorized in three stages. The first stage is high speed flame propagation induced by flame torches from the pre-chamber. The second stage is simple flame propagation in the main-chamber. This flame propagation speed is relatively lower than the first stage combustion, because turbulence kinetic energy is lower than that during the first stage. The curvature of rate of heat release relates to the surface area of flame front and excess air ratio in the flame front. The third stage is autoignition of the unburned mixture in the end gas region. Autoignition in the main-chamber occurs between the torches. The intensity of pressure oscillation and rate of heat release depend on both the mass of the unburned mixture in the end gas region and the onset positions of autoignition.

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A set of accurate estimate model and computer algorithm for installing in a control module of diesel engine exhaust is developed based on the data of differential pressure sensors and particulate matters. In the estimate model, the pressure drop vs. particulate matter loading relations are described for three different phases. Through a detailed examination of the original equations and its comparison with the experimental data, a simplified model equation is derived. The equation is that ΔP=C₁Q + C₂Q², where ΔP : total pressure drop, Q : volume flow rate, C₁ and C₂ :coefficients. The accuracy is confirmed by vehicle tests of European and North American driving cycle modes. The evaluated error is much less than the required tolerance of 0.5g/L.

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As well as utilitarian functions of commercial products, their visual quality has become significant in differentiating strategy. This study dealt with feel of translucency for scattering material, such as cultured marble and earthenware. A visual assessment based on a pairwise comparison technique is carried out to investigate the effect of an optical property and thickness of a planar scattering medium on its translucent feel, and the Thurstone scale is adopted to quantify the translucent feel. The results reveal that the feel strength of translucency for a planar scattering medium is proportional to the optical thickness of the medium when the thick is less than 20, and that the planar media with the optical thickness more than 20 does not affect the translucent feel.

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Natural convective flow and heat transfer induced around a vertical row of heated plates were investigated experimentally. The experiments were carried out with the row of ten-plates of heights L=20, 30, 50mm. The plate row was placed in the air with vertical gaps ranging from G=5mm to 70mm. These enabled the experiments in the wide ranges of modified Rayleigh numbers, 2x10⁴<Ra_L^*<4x10⁶, and non-dimensional gaps (G/L)=0.1-3.5. The flow fields around the row were first visualized using a smoke. The results depicted that the plumes arising from the upstream plates remain laminar throughout the row when the gaps are smaller than 30mm. While when the gaps are larger than 50mm, the plumes sway randomly on the halfway of the row and the turbulent transition takes place. The average heat transfer coefficients from the plates in the row were subsequently measured. They showed a monotonous decrease toward downstream when the flow remains laminar. While when the turbulent transition occurs, they turn to increase. The coefficients were next arranged with various non-dimensional parameters to obtain heat transfer correlations. Among many parameters, the parameter Ra_G^*(G/L) was found to best correlate the present Nusselt numbers Nu_G, where Ra_G^* and Nu_G stand for the gap-based modified Rayleigh and the average Nusselt numbers. Moreover, from the plots in Nu_G - Ra_G^*(G/L) plane, the heat transfer correlations were proposed both for the laminar and turbulent flows. The proposed correlations are very simple, but can predict the Nusselt numbers quite satisfactory.

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For further reduction of particulate emission from a diesel vehicle, it is fundamentally important to understand in-flame soot formation and oxidation processes. In order to clarify the processes, the morphology of soot directly sampled at different locations in the spray flame (40 mm to 90 mm from the injector nozzle tip) were investigated using a transmission electron microscope (TEM). The diesel spray flame was achieved in a constant volume combustion chamber under diesel-like conditions (2.5 MPa and 940 K). The concentration, diameter of primary particles and the radius of gyration of soot aggregates increased in the upstream region (40 to 50 mm), exhibited a peak around the mid-stream region (60 to 70 mm), and then decreased in the downstream region (80 to 90 mm), which corresponds to formation, peak concentration and oxidation of soot particles in the spray flame, respectively. The fractal dimension of soot aggregates was also analyzed and was almost constant, with a value of approximately 1.73 over different axial locations in the spray flame, which suggests that the dominant growth process of in-flame soot aggregate is cluster-cluster aggregation in diffusion limited regime.

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We have been developing power assist suits as labor-reducing equipments for non-handicapped elderly, weak young and female workers. This paper describes the verification tests of validity of an electrically actuated power assist suit for practical use. This power assist suit supports the motion of antigravity direction using electric motors and arranges passive joints appropriately in order not to disturb wearer's motions. We realized the support of walking and lifting a heavy object. It is necessary to detect wearer's intention and predict following motion because the power assist suit is required to move simultaneously with the wearer. We estimate the motion intentions using hip joint angles, foot switches and glove switches, without using bioelectrical signals such as surface electromyogram signals, which usually have inferior S/N ratio. The experimental results of energy expenditure and oxygen consumption rate show the effectiveness of proposed mechanism and control method of power assist suit.

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The parasitic resistances of a piezoelectric element have been often neglected in the conventional analysis of a piezoelectric shunt damping system. This paper indicates that the parasitic resistances cause instability in the piezoelectric shunt damping system with a simple negative capacitor circuit by both numerical simulations and mathematical analysis based on the Routh-Hurwitz stability criterion. This paper then proposes a new two-step design procedure for a modified negative capacitor circuit by taking account of the parasitic resistances. The negative capacitance and the resistance in the circuit are firstly designed based on the fixed-points theory of tuned mass damper, and then, the negative resistance in the circuit is adjusted based on the pole placement technique. The effectiveness of the proposed method is demonstrated by the damping experiments.

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This paper deals with a structurally-acoustically coupled rectangular cavity comprising a flexible windowpane and five rigid walls. It is the purpose of this paper to perform active control of a windowpane with a view to enhancing its transmissibility loss. First, using an operational modal analysis the coupling effect emerging on the windowpane under a strongly coupled cavity is investigated. It is then found that there exist two kinds of coupled modes: one is dominated by an in vacuo vibration mode of a panel and the other by an acoustic cavity mode. Among the latter modes an isolated implosive mode is found, which is predominantly governed by an acoustic cavity mode due to a specific support of a windowpane. It is further revealed that the isolated implosive mode may not be suppressed by vibration control, but by acoustic control only. Finally, active structural-acoustic control is performed on the windowpane, demonstrating sufficient control effect over all the coupled modes with synergy effect as a result of employing both vibration and acoustic control.

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This study will address the improvement of the analytical accuracy of a lateral vibration analysis model for rotor-dynamics. In case of predicting the lateral vibration of a rotor with disc elements fixed on the shaft by the interference fit, the accuracy of the bending stiffness of the corresponding shaft element could affect the accuracy of the predicted vibration property. This paper describes the investigation results for estimating the bending stiffness of a rotor with a sleeve fixed on it by the interference fit using the finite element analysis model which can treat the contact problem including the friction effect. The results show that the bending stiffness of a shaft element with a sleeve depends on the occurence of the relative slip on the fitting surface, and the bending stiffness is equivalent to the one of a solid shaft element that has the same outer diameter as the sleeve when the relative slip does not occur. Additionally, we have evaluated the natural frequencies of a shaft with a sleeve on it using the improved 1D finite element model and the vibration test. The approximate critical amount of the bending moment which will cause the relative slip on the fitting surface is estimated by the analysis. Comparing this amount of to the bending moment caused by gravity and unbalance force acting on the horizontal rotor, we have obtained the permissible quality factor Q in resonance for a given balance quality.

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This paper presents a novel numerical model of the rate-dependent hysteresis. The model has the structure of adaptive linear combiner (ALC) where the states of magnetization of the discretized Preisach plane constitute the input signal sequence of ALC. An adaptive update law with forgetting scheme is designed to update the coefficients of the ALC model to capture rate-dependent behavior of the hysteresis. An input-output behavior of a bimorph type piezo ceramic actuator has been selected as the experimental target to verify accuracy of the proposed hysteresis modeling scheme and the results clarify that the proposed model shows excellent performance for sinusoidal inputs having frequency lower than the resonance of the actuator. Results will be deteriorated for higher frequencies where phase lag might be observed in the corresponding output displacement response of the actuator. However, it has also been shown that appropriate use of FIR filter to the input sequence of ALC largely restores modeling accuracy for those frequencies.

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Acoustic damping in narrow slit becomes significant issues when the slit width is comparable to viscous and thermal skin depth. Acoustic transfer functions between two cavities connected through a narrow slit cannot be predicted precisely by the conventional Helmholtz equation. In this study, air is considered as compressible viscous fluid and linearized Navier-Stokes equation is applied assuming that amplitude of particle velocity is very small. Fourier's law is also applied to account for thermal conductivity between air and surrounding structure. Then, two acoustic damping mechanism can be considered; viscous dissipation in the vicinity of boundaries between air and surrounding structure and thermal dissipation from medium to surrounding structures. Finite element discretization of narrow slit is studied to express gradient of velocity and temperature profile in the vicinity of the boundary between slit and surrounding structure. Velocity obtained numerically is compared to analytical solution and error on the velocity averaged in a cross-section is considered. A simple test rig that has two acoustic cavities connected through a narrow slit is created. Numerical predictions agree well with measured results although computational cost is considerably high. Equivalent density and bulk modulus to be applied in Helmholtz equation are calculated by averaging velocity, pressure, temperature variation. The properties can be applied to other systems as long as the dimension of the slit remains unchanged.

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This paper propses a numerical simulation model for the unwinding behavior of a bobbin yarn based on the multibody dynamics method. When the edge of a yarn, wound on a bobbin, is pulled in upper direction, it starts moving naturally from the static condition and shows a ballooning behavior. A yarn model is constructed by particles connected to each other, and its motion is numerically analyzed under the action of a contact force by a wall. In an unwinding process, since the yarn is unwound sequentially from the bobbin, the total length of the yarn becomes very long and the number of particles representing the yarn becomes a large number. In this paper, only the part of the yarn between the unwound point and the pulling point is considered in order to reduce the calculation load. As the yarn moves with time, the part of the yarn which starts moving at the bobbin is added to the range of calculation, and the part of the yarn which reaches the pulling point is removed from the range of calculation at each time increment of the numerical simulation. The numerical result is compared with the experimental result and their shapes of ballooning behavior show quantitative agreements. As a result, the validity of the proposed yarn model of the unwinding process is verified.

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The modern agriculture shows remarkable results in productivity for labor saving by mechanization. However, it is still difficult to replace the dexterous human ability in handling objects with mechanisms. Many tasks in agriculture depend on human dexterity especially when it comes to pluck delicate fruit without damage to preserve quality. Strawberry is one kind of fruit that needs extra handling care during plucking, due to its brittleness against force and heat. Therefore, detailed observation and evaluation need to be done in order to produce a harvesting machine. This paper proposes strategy and design of finger for strawberry harvesting. In the strategy, there are three cases which are "cutting after holding," "holding after cutting" and "same timing of cutting and holding". In the cutting after holding and the same timing of cutting and holding, it is complex and heavy for the mechanism to achieve them. In the opposite case of the holding after cutting, it is easily achieved by simple mechanism which is a holding finger with an edge. However, high velocity of closing finger is needed to certainly grasp the stem during its free fall. A problem that a general robot hand loses grasping the stem is occurred, since closing velocity is insufficient. Therefore it is applied for the insufficient velocity of the closing to follow up it on restoration of elastic deformation of the finger. It deploys a pair of elastic, flexible fingers to cut and grasp the stem before the fruit falls. An experimental device was developed for strawberry harvesting, and mounted on a harvesting robot. Its performance was analyzed and evaluated, Results showed it worked as designed and intended.

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In human gait motion analysis, which is one useful method for efficient physical rehabilitation to define various quantitative evaluation indices, joint angles and joint moments are measured during gait. On the one hand, human keeps a high correlation among the motion of all joints during gait. Joint motion analysis of the correlation extracts a few simultaneously activating segmental coordination patterns, and the structure of the intersegmental coordination is attracting attention to an expected relationship with a control strategy. However, when the evaluation method using singular value decomposition has been applied to only the restrained unnatural gait by laboratory, natural gait on stairs and slopes as the activities of daily living has not yet been considered. In this paper, analysis of principal components concerning joint angles and joint moments during gait based on the focus on upstairs, downstairs, upslopes and downslopes is aimed to clarify spatial coordination patterns of practical human gait. Each physical parameter of healthy subjects is measured by using mobile force plate and attitude sensor. As a result of the experiments and data analysis, singular value decomposition extracts the motion pattern with high correlation from the physical feature quantities and specific points of differences between gait environments are revealed. In the end, consideration of mutual comparison is performed from a biodynamic viewpoint and the validity of quantitative evaluation is verified.

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This paper tries to clarify how rocking motion and body structure effect on the emergence of walking and the changes of the gait such as walking speed and the length of stride. Humans naturally exhibit adaptive performance in various environments. Moreover, they are able to adjust the gait for their purposes. The adaptive locomotion is generated not only with leg swing motion, but also the lateral rocking of the body, rotation of the center of mass, etc. Most previous researches have mainly mentioned the direct drive of the legs. On the other hand, one previous research has indicated interesting motion observation that the body motion in lateral plane will get to a dominant factor in the phase of low speed walking. According to the previous result, we propose an idea that the walking can be generated by an excitation of lateral rocking of the body without direct actuations of legs. Therefore, in this paper, we especially focus our attention on three-dimensional quasi-passive walking provoked by the rocking motion of the robot body in lateral plane. After developing a robot with an oscillator that excites rocking motion of the robot body in lateral plane, we confirmed the emergence of walking in the experiment. Next, we investigated the gait difference by changing the parameters of the rocking motion (amplitude, period) and the robot body structures (length of the leg, offset of the legs to forward). The experimental analyses indicate that the walking speed, robustness and consumption of energy are mainly correlation to the period of lateral rocking and the offset of the legs to forward. In summery, an appropriate combination between the period of rocking motion and structures of the robot body leads to control of the gait.

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We developed a valve hybrid fractal stent to treat the cerebral aneurysm what is one of a cerebrovascular disease. The stent has a valve part to path through a coil. The valves have fractal structures. So, the blood flowing into cerebral aneurysm is prevented. We performed a Particle Image Velocimetry (PIV) experiment to evaluate the inflow into cerebral aneurysm. By the experiment result, we visualized the stream line by using the cerebral aneurysm. By calculation, we succeeded in a reduction in the inflow by using the valve fractal stent.

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For error-free computation of high-derivatives of mathematical functions used in engineering applications, hyper-dual numbers (HDN) are receiving much attention in computational mechanics. Differently from classical finite differences, HDN provides a practically exact evaluation of higher-derivatives, such as the first and second derivatives of stiffness matrix with respect to nodal degrees-of-freedom (dof). As a preliminary step for introducing HDN in stability problems, the present paper formulates the theoretical basis of a 2-mode asymptotic bifurcation theory and examines its versatility on simple bench models. All obtained results in numerical examples well predict the stability behavior and agree with existing analytical solutions.

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Miniaturization and lightweight are necessary for the reduction gear used in aviation/space machines and cars. The proposed system comprises a combination of a gear and a rolling bearing into a traction drive system because the rolling bearing has a function that reduces rotational speed and supports gear reaction forces. The traction drive system features an input shaft, an inner ring with a fixed outer ring, and a retainer as the output shaft. The retainer of the rolling bearing and the output shaft were integrated and could be further reduced using the difference in the rotational speed of the inner ring and the retainer. The system requires preload to use a rolling bearing as a traction drive. Adding preload axially requires an extra space for the spring to preload. In this study, preload in the radial direction was induced to save space by placing a ring outside the outer ring utilizing shrink fitting. Thus, a theoretical transmission gear ratio was attained and the system successfully operated up to a torque of 20 Nm. The transmission efficiency was confirmed to be 86.8% because of double reduction by the gear and the traction drive system.

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It is well known that the characteristics of exiting force of planetary gear mesh are varied with gear mesh phase between pinions in single pinion type planetary gear set and that the sideband phenomenon occurs in the sequentially phased planetary gear set. This sideband phenomenon is one in which the (Z-1) or (Z+1) order component level is higher than the mesh order (Z) component level. The notation (Z-1) or (Z+1) means the mesh order (Z) minus or plus one carrier revolution. In this study, the relationship between gear mesh phase and vibration behavior is investigated in the stepped pinion type planetary gear set which has two mesh order component and is operated at wide frequency range. The formulae of mesh force of 6 degrees of freedom acting in sun gear, carrier and ring gear respectively are derived for stepped type planetary gear set. From the experimental and calculated results, the same side band phenomena were also observed in the stepped type planetary set. By taking into account the side band order component of gear mesh, it was revealed that the influence of gear mesh phase on the characteristics of unit case vibration is varied by frequency range. It is considered that the dominant direction component of exiting force for the case vibration of applied unit moves from transverse direction at low- frequency range to rotation direction at high-frequency range.

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In this study, in-situ observations of a contact interface between a transparent rubber hemisphere made of PDMS (poly dimethyl siloxane) and a smooth plate made of PMMA (polymethyl methacry- late) were performed. Using a reflective optics, the space distribution of real contact regions formed in the apparent contact region was visualized. Additionally, the normal load dependence of friction force that acts on the contact interface was also investigated. As a result, it was found that the classical Amontons' friction law breaks down in this system; friction coefficient gradually decreased with increasing normal load. Based on Persson's contact theory, we discussed the mechanism of the normal load dependence of real contact area and friction coefficient. Finally, a novel method for estimating the real contact area and shear strength in sliding friction of a rubber like material was developed. The use of this method allows to estimate the real contact area and shear strength without any optical measurements of contact interfaces.

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Frictional Stir Burnishing (FSB) is a surface enhancement method after machining without using additional device. The FSB process can be utilized on the machine tool which uses the rotation tools such as a machining center and a multi-tasking machine. Therefore, the FSB process can be applied just after the cutting process on the same machine tool. FSB was applied to the shaft materials of 0.45%C steel by using a multi-tasking machine in this paper. FSB is a process where the burnishing tool rotates at high revolution speed. Then the thin surface layer is rubbed and stirred with a temperature elevation and reduction. However it is difficult to achieve both high hardness and high compressive residual stress by FSB on 0.45%C steel shaft with helical path. In order to overcome this problem, FSB process with double helical path was proposed in this paper. As a result, both high hardness (600 HV) and compressive residual stress (-400 MPa) could be achieved.

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This paper presents tool life (flank wear) and crater wear of four kinds of coated high-speed steel tools and finished surface roughness in hobbing under the conditions of considering environment. Experiments were conducted by simulating hobbing by fly tool cutting on a milling machine. As a consequence, the following results were obtained. (1) Under the condition of 1-thread hob, TiN- and AlCrSiN-coated tools showed the longest tool life among the four kinds of coated tools in dry and with MQL system. Under the condition of 3-thread hob, TiSiN-coated tool is effective in dry, and TiAlN- and AlCrSiN-coated tools are suitable with MQL system. (2) The crater wear of TiN-coated tool is smallest in other coated tools tested both in dry and with MQL system under the condition of 1-thread hob. TiAlN-, TiSiN- and AlCrSiN-coated tools are effective, and it was suggested that the crater wear is protected by the deposited metal under the condition of 3-thread hob. (3) The finished surface roughness, which was obtained with almost of coated tools tested at the end of cutting with MQL system both under the conditions of 1- and 3-thead hobs, is smaller than that obtained by dry. (4) From the viewpoints of tool life, crater wear and finished surface roughness, AlCrSiN-coated tool is suitable for hobbing with MQL system.

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