摘要 :
The purpose of this report is to discuss the behaviour of bolted joints tightened in plastic region. Although, there have been many reports about plastic region tightening method, their method and discussion were based on the clas...
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The purpose of this report is to discuss the behaviour of bolted joints tightened in plastic region. Although, there have been many reports about plastic region tightening method, their method and discussion were based on the classical criterion derived from the rigid-plastic solution for combined loads of axial tension and torsion. Recently, the finite element method is receiving attention in various fields of engineering because of its diversity and flexibility. In this report, a finite element modeling of bolted joint was performed to confirm the validity of the computer program developed for plastic region tightening analysis.
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This paper deals with the vibration control device that simultaneously generates electricity by using absorbed vibration energy. This device is composed of a generator and a Hula-Hoop that is fixed on the shaft of the generator. A...
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This paper deals with the vibration control device that simultaneously generates electricity by using absorbed vibration energy. This device is composed of a generator and a Hula-Hoop that is fixed on the shaft of the generator. As the conditions which have some effect on the vibration control performance and electric power, power of D.C. motor that is the substitute of generator, weight of Hula-Hoop, distance between the center of rotation and center of gravity, external frequency, and initial condition are examined.
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Recently, motorized equipment is required in order to support ADL (Activities of Daily Life) of the elderly. Authors are developing mobile type walking support systems. In this development, we understood the requirement for the as...
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Recently, motorized equipment is required in order to support ADL (Activities of Daily Life) of the elderly. Authors are developing mobile type walking support systems. In this development, we understood the requirement for the assistance in standing-up and sitting-down motion is very important. We started to study about the elemental technologies of standing-up and sitting-down motion assisted by upper body support arm (which is used for mobile type walking support systems). This paper describes the study on the support arm trajectory during this assisted motion. We developed a program to analyze the load acting lower limb joints in the motion. Using experimental data of supporting force, joint positions, and ground reaction force, joint torque was calculated in some trajectory patterns. Means to evaluate performance of the arm trajectory were obtained.
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A dynamics study of herringbone-grooved gas journal bearings is presented placing emphasis on a comparison between infinite and finite groove number solutions. The study is conducted under practical operating conditions by means o...
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A dynamics study of herringbone-grooved gas journal bearings is presented placing emphasis on a comparison between infinite and finite groove number solutions. The study is conducted under practical operating conditions by means of nonlinear orbit approach. The analysis scope includes a grooved member rotating system as well as that with a smooth member rotating. Numerical examples show that the infinite groove number assumption predicts the self-excited half-frequency whirl stability with tolerable accuracy unless the rotor is fully grooved.
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Concave conical gear is a new type of conical gear invented by one of the authors. This new gear is based on the conical gear and besides can take a larger allowable normal load than the conical involute gear. But the grinding mac...
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Concave conical gear is a new type of conical gear invented by one of the authors. This new gear is based on the conical gear and besides can take a larger allowable normal load than the conical involute gear. But the grinding machine of the Concave conical gear has not been developed hitherto. So the authors aim to newly devolop a gear griniding machine for this gear. First the principle of generating the Concave conical gear presented, and the practical generating method is also presented on this principle. Secondly the grinding machine is developed. Mechanism and motion transmitting system are invented. Truing method for the conical-shaped wheel is also presented. Finally grinding test are performed. Measurement of the tooth surface verifies that the ground tooth surfaces are in good agreement with the theoretical ones. This fact proves that the new gear grinding machine has a possibility for practical use.
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Evaluation parameter of magnetic damping characteristics is needed for the mechanical design of structures located in a high magnetic field. In this paper, the coupling intensity parameter is proposed as an evaluation parameter of...
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Evaluation parameter of magnetic damping characteristics is needed for the mechanical design of structures located in a high magnetic field. In this paper, the coupling intensity parameter is proposed as an evaluation parameter of the vibration with magnetic damping. To verify that the magnetic damping characteristics are represented by the coupling intensity parameter, experiments and numerical analyses were performed. The conditions were obtained to keep the two parameters unchanged, namely the coupling intensity parameter and the time constant ratio of the eddy current and structure, using the dependence of the coupling intensity parameter. Since the damping charac- teristics of these cases agree very well, it is confirmed that the coupling intensity parameter and the time constant ratio are the evaluation parameters of the vibration with magnetic damping.
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In this paper, the fabrication method of the BP/C/C composites, and the effect of bamboo charcoal on the wear and friction properties were investigated. The matrix was phenol resin, and reinforcements were Bacterial Cellulose (BC)...
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In this paper, the fabrication method of the BP/C/C composites, and the effect of bamboo charcoal on the wear and friction properties were investigated. The matrix was phenol resin, and reinforcements were Bacterial Cellulose (BC) and Bamboo charcoal particles (BP) as Si additive. The effect of BP weight contents on wear and friction performance has been experimentally investigated. Samples were prepared by carbonizing at temperatures of 700°C to 1000°C. The wear tests were carried out by using pin on drum type wear testing apparatus for constant dry sliding conditions. From the experimental results of wear tests, the wear and friction properties of the BP/C/C composites were dependent on the content of BP wt% and carbonizing temperature. The composites with 5wt% BP carbonized at 900°C indicated the lowest friction coefficient of 0.14 among the composites. The composites with 5wt% BP carbonized at 1000°C exhibited the lowest wear rate of 2.25×10-10 [mm2/N]. Compared with the nano-C/C composites with BC and Phenol resin and the BP/C composites, the BP/C/C composites with optimum BP wt% at higher carbonizing temperature showed lower wear rate and friction coefficient. The experimental results indicated that bamboo charcoal can be applied as filler which can provide lower wear rate and friction coefficient.
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Muscle fatigue should be quantitatively evaluated in order to design an optimum work environment and work-rest scheduling and prevent musculoskeletal disorder of workers. The aim of this study was to formulate a relationship for t...
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Muscle fatigue should be quantitatively evaluated in order to design an optimum work environment and work-rest scheduling and prevent musculoskeletal disorder of workers. The aim of this study was to formulate a relationship for the dependence of perceived muscle fatigue (PMF) on time and external load. Three differential equation models―saturate, non-saturate, and hybrid of saturate and non-saturate―were proposed for the PMF function. An elbow flexion task was performed with varying load amplitude (percent of maximum voluntary contraction, %MVC), and the PMFs were measured every 30 s during the task execution. The three models were applied to the measured PMFs and compared in terms of their PMF prediction accuracy. In addition, the maximum endurance times (METs) predicted by the three models were compared with the existing MET models. The measured result showed that the PMF increased logarithmically at the relatively low %MVC and linearly at the relatively high %MVC. The hybrid model was selected for the PMF function, because it showed a better fit to the measured PMFs and a higher interclass correlation with the existing MET models. Individually approximated PMF functions for males and females did not show an improved accuracy compared with the PMF function for both genders. Therefore, a single PMF function was applied irrespective of the gender.
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This paper describes stress analysis of SS400 natural rubber (NR)-bonded structures, assuming large deformation, applying the finite element method. We first carried out a comparison of the stress components σ_(θθ) and τ_(rθ)...
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This paper describes stress analysis of SS400 natural rubber (NR)-bonded structures, assuming large deformation, applying the finite element method. We first carried out a comparison of the stress components σ_(θθ) and τ_(rθ) for each singular point for width of adhesive w = 30 mm. Next, a stress analysis was performed on SS400 NR-bonded structures using the delamination force previously obtained by delamination testing. Finally, the intensity of the stress singularity, K_(θθ) , obtained from a geometrically nonlinear analysis, i.e., large deformation analysis for linear elasticity, and geometrically nonlinear analysis considering material nonlinearity, i.e., large deformation analysis for hyperelasticity, were evaluated using several computational models while varying the width of the adhesive.
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An inertia damper with a long spiral bypass pipe was developed in order to obtain a series inertia effects for vibration suppression of structures in practical use. The damper comprised a cylinder, piston, and MR fluid. The gap wa...
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An inertia damper with a long spiral bypass pipe was developed in order to obtain a series inertia effects for vibration suppression of structures in practical use. The damper comprised a cylinder, piston, and MR fluid. The gap was spirally formed around the outside of a cylinder, and acted as a long bypass pipe. MR fluid is well known for its changeable damping effect, but the mass of the fluid is the focus of this study. It is obvious from previous studies that a fluid inertia effect is caused by quick motion in the long bypass pipe, and it depends on the length of the bypass pipe, compression ratio of area, and density. A large inertia effect can be derived if the fluid has a heavy mass. In order to confirm the inertia effect, a prototype damper was manufactured, and resisting force characteristics were measured. Seismic response tests using a 3-story structure were then performed using a shaking table with the damper installed. Each story of the structure had a height of 3 m, and a weight of 6 tons with a total height of 9 m and a total weight of 18 tons. Several types of earthquakes were input, and the response acceleration, relative displacement, and reaction force were measured. Finally the effects of vibration reduction were confirmed experimentally, and a feasibility study was discussed.
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