This paper deals with the effect of adhesion layer and material combination on the stress intensity factor for small edge interface crack in butt joint plate under uniaxial tension. The stress intensity factors of the small edge interface crack are analyzed by the crack tip stress method with varying the crack length, adhesive thickness and material combination. The stress intensity factor of the edge interface crack is controlled by the singular stress field at the interface free edge in butt joint without the crack when the crack is very small. The calculation shows that the stress intensity factors K₁ and K₂ of the small edge interface crack are related to the intensity of singular stress field K_σ and the singularity index λ₁₂ at the interface edge without the crack. Then, it is found that the stress intensity factors can be expressed as K₁ ＋iK₂ = (F₁ ＋iF₂)K_σa^{λ₁₂－0.5} √π(1＋2iε) and the normalized stress intensity factors F₁ and F₂ are constant values when the crack length a/h<10^-2 irrespective of the adhesive thickness and length of butt joint plate. Therefore, it can be concluded that K₁ and K_σ are an equivalent parameter each other.

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Applications of fiber reinforced plastics have been expanding due to improvement of not only fuel efficiency but also the motion performance of some recent vehicles. Especially, the demand for injection-molded fiber reinforced thermoplastics is expected to increase because of their superior moldability, productivity and recyclability. In this study, the influence the fiber diameter has on the impact tensile properties of long glass-fiber reinforced polyamide (GF/PA) is investigated using the split Hopkinson pressure bar method. Prior to the tensile tests, an investigation of the fiber-orientation distribution was conducted in order to cut out specimens with the same fiber orientation angle from the injection molded plate. Two types of specimens, referred to as specimens with high- and low orientation angle, were manufactured using glass fibers with average diameters of 13, 17, 23 μm. In the tensile test, the GF/PA with smallest fiber diameter showed the highest tensile strength and the most significant strain rate dependency on the strength. These effects were more significant for the specimens with high orientation angle. From SEM observations on the fracture surface and an average fiber length measurement, it was observed that the interfacial fracture and the fiber breakage were dominant failure modes under the considered tensile loading conditions. It was suggested that decreasing the stress acting on the fiber/matrix interface by reducing the fiber diameter affected the improvement of the GF/PA strength. Using the modified linear rule of mixtures, the tensile strength was predicted. The predictions showed good agreement with experimental results. Therefore, it is believed that the decrease of critical fiber length is the reason that the impact tensile properties are higher for the samples with smaller fiber diameter.

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This paper discusses the effects of weld bonding for flanges on the 3-point bending strength and axial compression strength of high strength hat-shaped steel sheet members. The effects of weld bonding were different depending on the loading direction and shape of the hat-shaped members. The deformation load increased in cases where the vertical walls of the hat-shaped member were deformed inward of the components. On the other hand, the load did not significantly increase in cases where the vertical walls were deformed outward of the components. When adhesive enhanced the load of the hat-shaped member, the load was higher than that of the laser welded member. It was revealed that adhesive present in the corner portion rather than in the parallel portion of the flange increases the load acting as the deformation resistance of a hat-shaped member.

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Application of carbon fiber reinforced plastics (CFRP) pipes to torque transmission shafts makes it possible to improve automotive driving performance as well as fuel efficiency. A modified simultaneous multi ply winding method was developed as a new forming method for CFRP pipes using prepregs. The CFRP pipes formed by the method have fewer initial flaws, such as voids and fiber waviness. It resulted in 20 % increase in the static torsional strength than conventional CFRP pipes formed by a filament winding method. In this study, effects of stacking sequence on the torsional fatigue properties of the CFRP pipes formed by the modified method were investigated. Torsional fatigue tests were conducted under load control. All tests were conducted at the test frequency f=1 Hz, the maximum applied torque T_max=1.0 kNm and the stress ratio R=0.1. [90₂/-45/+45]₆ and [90/-45/90/+45]₆ pipes were formed to investigate effects of lamination angle difference between adjacent plies. Maximum lamination angle difference of the [90/-45/90/+45]₆ pipe is smaller than that of the [90₂/-45/+45]₆ pipe. When the CFRP pipes had smaller lamination angle difference, the initiation and growth of the delamination from the prepreg end in the innermost layer were delayed because interlaminar stress was reduced. Moreover, [(90/-45/90/+45)₆/90] pipes were formed to investigate effects of an application of a 90° layer on the innermost layer. As the result, the delamination hardly initiated since the shear stress on the prereg end was reduced. Consequently, the fatigue life of the [(90/-45/90/+45)₆/90] pipes increased seven-fold than that of the [90₂/-45/+45]₆ pipes due to improvement of delamination resistance under cyclic torsional loading.

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Recently, the fuel consumption improvement by weight saving is required in transportation machine. Therefore, Mg alloy is expected as the alternative material of Al alloy and resin material, because it is the lightest in the practical metals and its specific intensity is high. However, twin crystal deformation occurs easily, and there are the two kinds types (i.e. {1012} and {1011} twin crystal) in that deformation. It has been reported that the {1012} twin crystal has work to relax the stress concentration and the {1011} twin crystal has close relation to fracture. Our aim is to evaluate the kinds and the conditions of those types with AE method. In this study, Mg alloy AZ31 was used, and the AE signals of the alloy were detected in compression, tensile and CT test. After that, the analysis of those signals were done. From the results obtained under this experimental conditions, the following things became clear. (1) The frequency components near 250, 550 and 850 kHz are caused by slip, twin crystal deformation and crack growth respectively. (2) It is possible that the two kinds crystal deformation types are discriminated by the identification standards decided by the AE count and fractal dimension Fd of the detected signals.

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Elastoplastic analysis of solid structures under cyclic loadings is increasingly required in recent years. To this end, it is necessary to adopt elastoplastic model capable of describing cyclic loading behavior and to employ stress integration algorithm that enables effective and robust calculation. The subloading surface model excluding a purely-elastic domain is capable of describing the cyclic loading behavior in addition to the monotonic loading behavior. The complete implicit stress-update algorithm by return-mapping based on the closest-point projection for the extended subloading surface model is formulated in this article. In addition, the consistent tangent modulus tensor required for the accurate calculation by the return-mapping is formulated in the inverse matrix form. They are implemented into the implicit finite element program through the user-subroutine. We simulate elastoplastic behavior of metals to assess calculation accuracy and efficiency of the proposed algorithm. Numerical experiments for cyclic loading behavior of metals are shown in order to verify the accuracy and the efficiency of the computer program based on the return-mapping and the consistent tangent modulus tensor.

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In order to study the hydrogen embrittlement behavior of austenitic stainless steel weld metals, slow strain rate tensile (SSRT) tests were performed in 106 MPa hydrogen gas at -45 °C. Tensile specimens, in which whole of the gauge section consists of weld metals, were machined out from a TIG welded round bar. The base metal of multi-pass welded bars was SUS316 (hi-Ni), and the filler metals were 317L, 316 and 316L. The nickel equivalent values of SUS316 (hi-Ni) base metal, and 317L, 316 and 316L weld metals were 29.69, 29.99, 28.87 and 28.27 mass %, respectively. Two series of weld metals were tested; one was as-welded metal, and the other was post-welded solution-treated weld metal. The relative reduction of area, RRA, was 0.55 for 317L as-welded metal, and approximately 0.9 for SUS316 (hi-Ni) base metal and 317L, 316 and 316L post-welded solution-treated weld metals. The result indicated that the resistance against hydrogen embrittlement was recovered by the post-welded solution-treatment. The fracture surface of SUS316 (hi-Ni) base metal and 317L post-welded solution-treated weld metal was entirely covered with dimples, whereas the fracture surface of 316 and 316L post-welded solution-treated weld metals was covered with dimples and quasi-cleavages. Accordingly, it was concluded that 317L post-welded solution-treated weld metal with the highest nickel equivalent had excellent resistance against hydrogen embrittlement, which was recommended for use in high-pressure hydrogen components.

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This study deals with the time-mean aerodynamic characteristics of a concentrator photovoltaic system (CPV), which is mainly composed of a rectangular panel and a cylindrical shaft. It consists of wind tunnel and water tank experiments. Attention was focused on the effects peculiar to the flow around the CPV. First, placing a scale model in a wind tunnel, we made measurements on its aerodynamic characteristics for different incidence angles φ and yaw angles θ of the panel relative to the direction of the oncoming flow. The aerodynamic characteristics were examined for the case with the panel settled vertically, i.e., φ is set to 0°, but θ is varied. The results are fairly close to those of a single square plate by other investigators. For non-zero values of φ, however, the differences of the aerodynamic forces are perceived between two cases taking two attitudes for which each other is mirror images. The distribution of the differences is displayed on the φ-θ plane. Here, the corresponding cases where the acceptance surface faces upstream and downstream are called ‘upstream-facing case’, and ‘downstream-facing case’ respectively. This analysis clearly shows a trough showing more pressure recovery for the upstream-facing case. Next, to make clear the cause of the pressure recovery, we performed flow visualization in a water channel, where fluorescein dye was injected into the near-wake regions of the model. The flow visualization indicates that the pressure recovery is probably due to a difference between upstream- and downstream-facing cases in development of the shear layer separated from the side with a larger separation angle . The upper separated shear layer rolls up freely for the downstream-facing case, but the growth of the lower one is inhibited by the ground for the upstream-facing case.

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Under a high Schmidt number condition, concentration boundary layers get much thinner than momentum boundary layers. Resolution requirement to numerically capture the steep concentration gradient near an interface is therefore significantly high. This article presents a novel VOF-based method to predict mass transfer from gas-liquid interfaces using a computational grid of a marginal resolution required for the solution of the Navier-Stokes equation. The solution procedure to the mass conservation equation is divided into two steps: the dissolution and diffusion step and the advection step. The concentration profiles near gas-liquid interfaces, which are identified as segments (in case of two-dimensional computations) in each computational cell, are reconstructed in terms of the complementary error function by virtue of the boundary layer approximation to the solution of the unsteady advection-diffusion equation of mass. The amount of dissolution from the interfaces and diffusion in the vicinity of the interfaces is obtained by taking advantage of the reconstructed concentration profile on each interface segment. In the advection step, the un-smoothness of concentration profiles in the interface cells is explicitly taken into consideration by taking full advantage of a VOF advection scheme. The present method is validated in two-dimensional test problems with the Schmidt number of 100 which cover a pure diffusion problem and a mass transfer problem from a freely rising buoyant bubble. The validation shows the present method is capable of resolving a concentration boundary layer which is as thin as a computational cell. The reduction rate in the overall computational cost is O(10^-3) compared to one of the conventional methods (Ezu et al., 2011) without the subgrid-scale resolution.

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A synthetic jet is generated by an oscillating flow that a time-averaged mass flow is zero, unlike continuous jets. Synthetic jets have been used for various applications such as mixing enhancement and active controls. The present study investigated flow characteristics of a synthetic jet by using the vortex method. Continuous and synthetic jets were simulated by distributed sources on a slot and vortex pairs discharged from slot lips and their images. The wall boundary was simulated by the images of vortices. The onset condition of the synthetic jet by the vortex method agrees well with the Holman's result. The mean velocity distribution on the x axis by the vortex method reasonably agrees with the experimental one. For the dimensionless stroke lengths larger than 3.14, vortices remain in the flow field after the period of the suction. The induced velocity of the vortex remaining in the flow field generates the synthetic jet. During the suction, the largest velocity is located near a pair of the vortex groups. The 2nd local maximum in the mean velocity distribution corresponds to that in the frequency distribution of the maximum velocity. The 2nd local maximum is caused by a pair of the vortex groups flowing between x=15 and x=25 slowly.

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Since 1965, the number of cities constructing and operating sewerage systems had been on the rise, with waterway overhaul now prevalent in many parts of Japan. However, as the number of facilities under management has increased, their decrepitness has become obvious. The average service life of sewer pipe has been determined to be 50 years, but in reality, 30 years after pipes are built there is a tendency for rapid road subsidence and cave in. This situation stressed to us the importance of regular sewer pipe maintenance and inspection. In line with this, recently, robots have been actively used for inspection to reduce workload. However, the full system for the robots becomes large scale, resulting in high expense and poor maintenance. In this study, to solve these problems, we used the idea of a rescue robot, which we have been developing over a long period, to develop a small, portable inspection robot. Furthermore, we got a hint from "a secret box", one of Japanese traditional "wooden mosaic works" and assembled the module without using a single screw. This thesis details our work developing the small, autonomous pipe inspection robot and its specifications, including the updated hardware and software of the robot. The structure of the contrived "wooden mosaic work" was described. Its utility was confirmed through practical experimentation on its movement.

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Spacecraft inside a fairing of the launch vehicle is exposed to the severe acoustic environment during the lift-off and flight stages. Since the early days of spacecraft development, diffuse acoustic field is one of the critical design consideration of spacecraft structure because all the structural modes are excited equally by mutually uncorrelated plane waves from all incident angles, in the considered frequency range. However, there is some discussion about the difference of acoustic environment between fairing internal acoustics during launch and theoretical diffuse acoustic field for design. In previous researches, it has been discussed about the acoustic field during launch mainly focused on sound pressure level, while the effect to the random vibration of spacecraft structure from the difference of acoustic environment between fairing internal and diffuse field has not been much discussed, because it is difficult to asses the detail of the acoustic field due to limitations of the number of microphone located in the field. This provides the motivation for the present work in order to analyze the vibroacoustic data for spacecraft structures by using the normalized cross power spectrum density, which means spatial correlation of acoustic pressure. This paper concerned with the approach to estimate real value of the normalized cross power spectrum density using the least square approximation polynomial based on the Monte Carlo simulation, and calculate joint acceptance which is based on the estimated value. The approach is applied to the different environment between fairing internal acoustics and theoretical diffuse acoustic field, and is compared the normalized cross power spectrum density and the effect to the spacecraft structure from the difference based on joint acceptance theory.

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The aim of this paper is to explore the model calibration method consisting of the effective design of experiment (DoE) and the model selection for DoE. D-optimality is exploited as the cost function, and the optimal experiment design for the model is calculated by Fedorov's exchange method. An actual implementation example for air-mass flow model of gasoline engines is carried out. The model is chosen in the fashion of minimum cAIC criteria with the preliminary experiment for the purpose of the application of DoE. The experiment result with a full-scale engine test bench is validated to confirm that the proposed method can improve the accuracy of the calibrated model. The comparison of the proposed method with the conventional mesh experiment design by the calibration result is shown.

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In this study, we proposed a hybrid stator comprising a superconductor and a ring-shaped permanent magnet and measured the levitation characteristics of a magnet levitating above various hybrid stators. The magnetic field of the hybrid stator was equal to the composite magnetic field of the superconductor and the ring magnet. By adding a ring magnet, the vertical magnetic attractive force and stiffness were increased compared with those of a simple superconducting stator. Analysis of the calculated magnetic field for the ring magnet determined that the attractive force of the ring magnet and superconducting pinning force were effectively combined on the proposed hybrid stator. Although the maximum potential energy of stable levitation increased threefold, the horizontal magnetic stiffness of the hybrid stator was half of that of the simple superconducting stator at the initial pinning position. The proposed hybrid stator exhibits better levitation characteristics than a simple superconducting one. An improvement in the stability of the levitating magnet is realized by the hybrid stator using a superconductor and a ring-shaped magnet.

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A movable three-dimensional shape measurement system of a road surface has been developed. The measurement is conducted by moving the measurement cart along the path. The measurement system is composed of a 2D laser scanner, localization camera, omnidirectional camera, acceleration sensor and a computer. The laser scanner measures the cross-sectional shape of the road at a rate of 40 Hz. The direction of the localization camera view is downward to observe the texture of the road surface. The relative movement of the measurement cart on the road is detected by analyzing the optical flow of texture movements of the road. The localization camera is set as the laser scanning line is included in the view of the camera. The distance between the camera and the ground is considered on determination of the movement of the cart. Cross-sectional shapes of the road are arranged on considering the movement of the cart and the three-dimensional road shape is reconstructed on the computer. The color information recorded by the omnidirectional camera are allocated to the three-dimensional shape data, and the three-dimensional road is digitally visualized in color on the computer. The reconstructed road data can be used for repair and design of a road. The experimental results show the feasibility of our system.

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A flexible string is used at various places. Typical examples are a cable for power transmission and communication and a wire for cranes and elevators. In addition, there are the uses such as a fly-fishing line, climbing rope and a mowing machine to cut turf by turning a nylon string. In the past study, a string pendulum was paid attention as the basic motion of the string. An analysis model of the string pendulum was made and appropriateness of the modeling and the behavior of the string pendulum were clarified. However, axial elongation is not considered. In fact, the string extends in the axial direction by the mass of itself and the external force, and it is expected that the behavior of the string is affected by the axial elongation. Therefore, it is thought that it is necessary to carry out numerical simulation in consideration of the axial elongation in order to grasp the behavior of the string more exactly. In addition, it is indispensable to take elongation into account when we analyze the behavior of a string-formed structure producing the great amount of elongation such as the rubber string. In this study, an analysis model considering axial elongation is made. The behavior of the string pendulum and the behavior when the string is given initial elongation and is released are paid attention and appropriateness of the modeling is verified by comparing experiment results and analysis results.

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To design fast reactor (FR) core components, seismic response must be evaluated in order to ensure structural integrity. Sophisticated analysis method has been developed to study the seismic response of FR core. The fast reactors consist of several hundred core assemblies which are hexagonal flexible beams embedded at the lower support plate in hexagonal arrangement, separated by small gaps, and immersed in a fluid. Core assemblies have no support for fixing to avoid the influence of thermal expansion and swelling. So a nonlinear analytical model needs to contain the collision and the friction between adjacent core assemblies and the fluid-structure interaction in horizontal direction, and behavior of raising from the lower support plate in vertical direction. If a big earthquake occurs, large displacement and impact force of each core assembly may cause a trouble in control rod insertability and core assembly strength. Therefore, it is very important to understand the behavior of core assemblies. This paper summarizes the details of the core assembly vibration analysis code in three dimensions (REVIAN-3D) to calculate three dimensional displacement and impact force of core assemblies.

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This paper deals with the flutter analysis of a rectangular sheet supported by a wire in axial flow. In the flutter analysis, Doublet-Point Method based on unsteady lifting surface theory is used to calculate the unsteady fluid force acting on the sheet surface. The equation of motion of the sheet supported by a wire with tension is derived by using the finite element method. Flutter velocity and mode are examined through the root locus of the flutter determinant of the system with changing flow velocity. In this study, experiments are conducted and compared with the analytical results. The flutter velocity, flutter mode and the local work done by the fluid force acting on the sheet surface are determined. Moreover, the influence of eccentricity on the flutter velocity is clarified.

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We propose a rheology-based viscoelastic-viscoplastic constitutive model in which the deformation gradient is mutiplicatively decomposed into viscoelastic and viscoplastic components. The viscoelastic and viscoplastic rheology elements are connected in series, and the stress is determined only in the former element, which is modified by the back stress introduced in the latter one to represent the hardening due to orientation of molecular chains. The standard generalized Maxwell model is used to characterize the viscoelastic material behavior at small or moderate strain regime, while a proven finite strain viscoplastic model is employed to realize the transient creep deformations due to frictional resistance of molecular chains. After identifying the material parameters with reference to experimental data and verifying the fundamental performance of the proposed model in reproducing typical material behavior of resin, we carry out two kinds of numerical analyses for simple structures to demonstrate its applicability for practical use.

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In the 21^st century, as it is important to produce products with care for protecting the earth, a producer must be careful to conserve energy, save resources and reduce waste which pollutes environment. On the other hand, in case of a machine tool, much lubricating oil was used for smooth drive, electrical energy of forced cooling was used for high accuracy and much cutting oil was also used for lubrication and cooling. This is large problem for protecting the earth. Therefore a lathe with insensibility function for thermal and temperature change was developed and evaluated. The lathe has the structure of zero-center on three directions, the structure of self-compulsory cooling and the structure of thermal synchronism. Furthermore the wind control on the surface of the self-compulsory cooling using inverse analysis of neural network was developed for insensibility function of thermal and temperature change. Then thermal deformations of the developed lathe were measured and evaluated in the several experiments. It is concluded from the results that; (1) Thermal deformation of the bench lathe was very small in spite of no-forced cooling, (2) The wind control on the surface of the self-compulsory cooling using inverse analysis of neural network was effective for its working stability at weather change, (3) The lathe with insensibility function for thermal and temperature change was eco-friendly.

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Improving quality of hobbed gears must yield high accuracy of ground gears. This can be achieved by measuring hobbed gears accurately. Pitch deviations are most crucial in grinding processes with a worm type grinder. In the preset study, a new measuring method is proposed for single pitch deviations. In this method, measured helix trace data are conditioned with Gaussian Filter to be divided into short- and long-wavelength components. Single pitch deviations are calculated from the long-wavelength components around the center of facewidth. The calculated deviations showed 62.6 % lower variation in iterative measurements.

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The purpose of this study is to investigate the quantitative evaluation method for the hemiplegic gait characteristics by accelerometers installed in the right and left lumbar part. As the results of experiment on human walking the author has already examined, it is known that not only the component with frequency of 2fw, 3fw, but also the component with frequency of 0.5fw, 1.5fw, 2.5fw where fw is the pace frequency is observed. A FFT analysis for both hemiplegic gait and normal walking test results is carried out paying attention to the component with frequency of 0.5fw (half component of the pace frequency). Based on these analytical results, it is revealed that the component with frequency of 0.5fw in the traveling direction is obviously prominent for the hemiplegic gait compared with measured values of normal gait. This led to the conclusion that the half component of the pace frequency is the useful evaluation index for the hemiplegic gait from the viewpoint of rehabilitation.

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The G-G diagram is one way of expressing the cornering limit during braking or driving. When limit driving data is plotted on a graph with the 2 axes representing longitudinal acceleration and lateral acceleration, the shape of the graph indicates the cornering limit. Although the theoretical outline with a one-wheel model is a circle, the shape on the braking side of a G-G diagram which uses actual measured data is similar to a pentagon. As a result, the basic shape of the diagram is unknown. Therefore this paper proposes a graphical method which uses a two-wheel model to explicitly describe the mechanism that determines the G-G diagram shape. This graphical method is as follows. First, the provisional cornering limit line for the front wheel is plotted in the G-G diagram, ignoring the rear wheel cornering limit. Second, the provisional rear wheel cornering limit is plotted in the G-G diagram, ignoring the front wheel cornering limit. Third, the lower of the two cornering limit lines becomes the shape of the G-G diagram. The reason that the braking-side shape of actual measured data looks like a pentagon is due to the fact that these lines cross each other at two points. Furthermore, this paper describes the vehicle behavior when the diagram shape is the front wheel cornering limit line as “plow”, and the behavior when the shape is the rear wheel line as “spin”. Finally, this paper explains that the cornering limit increases in the order of rear-engine rear-wheel drive (RR), front-engine rear-wheel drive (FR), and front-engine front-wheel drive (FF) vehicles due to the effects of the engine position and position of the drive wheels.

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This paper proposes the drive training assistant system for ambulance drivers to avoid the excessive blood pressure variation of patients caused by brake operation. The system has two functions. The first is to estimate the blood pressure variation in real time based the acceleration of a car and to inform a driver with an electric sound when the estimated blood pressure variation exceeds the pre-specified level. The second function is to inform a driver of the start timing to apply a brake with a synthetic sound when the distance to a next intersection is less than the brake distance necessary to keep the blood pressure variation below the pre-specified bound. The brake distance is calculated in real time based on the present speed of the car, the passing speed at the next intersection, the slope angle of a road and the pre-given tolerable blood pressure variation. This paper mainly focuses on the second function and its availability. The prototype system was constructed using a commercial smartphone with a GPS sensor, a triaxial accelerometer and a speaker. The availability of the system was examined through the car experiment. It was confirmed that, by starting a brake operation after the brake timing announcement of the system, the blood pressure variation was controlled below the pre-specified tolerable bound.

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