The three-dimensional motion of balls in a tumbling ball mill is analyzed numerically by using DEM (Discrete Element Method). The effects of the ball filling ratio and the rotational speed of the vessel on contact force acting on balls in contact is analyzed. The impulsive force caused by collision is characterized by the force corresponding to its peak. The normalized frequency of the impulsive force monotonously decreased with increasing collision strength in all cases. It is found that the ball filling ratio and the rotational speed of the vessel largely affect the characteristics of the impulsive force. The present study predicts the existence of optimum conditions in the ball filling ratio and the rotational speed of the vessel.

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Vibration of the impeller of a single stage centrifugal pump was investigated experimentally. First the impeller was excited by an exciter when the pump was at a stop to investigate its vibration in still water. Next the vibration of the impeller and the pressure fluctuation acting on the pump casing were measured when the impeller was rotating in a vaneless diffuser and in a vaned diffuser respectively. The following results were obtained. (1) Water has a great inertia effect, especially when it is closed surrounding the impeller. (2) The vibration wave is a traveling wave along the circumferential direction of the impeller when resonance of a nodal diameter mode is excited by the fluid forces induced by impeller-guide vane interaction. The resonance frequency depends on the rotating speed of the impeller and the traveling direction of the wave. (3) The high frequency components of the fluid forces induced by impeller-guide vane interaction increase with flow rate, so that resonance excited by the interaction may result in troubles at large flow rate. (4) In actual pumps, resonance of nodal diameter modes may be excited even when the resonance condition of impeller guide vane interaction is not met.

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This paper deals with the prediction and the measurement of the resonant stress of compressor vanes of the gas turbine due to fluid exciting forces such as the rotating stall, the viscous wake and the potential flow interaction. First, the dynamic characteristics of the vanes such as the natural frequency and the logarithmic decrement are described. Second, the measurement method and the measurement results of the vibration stress of the vanes are presented. Finally, two of these results (the resonance stress due to the viscous wake of the preceding blade row and the potential flow interaction) are compared with the theoretical ones based on the classical aerodynamic theory. It is clarified that the theory is useful for the prediction of the resonant stress of the vanes subjected to fluid exciting forces.

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Totally enclosed induction motors in which the stator core is pressed in the frame are in general used in industrial machines and manufactured with similar construction around the world. Some of these motors produce a strong electromagnetic noise, which is caused by resonance between the natural frequencies of the stator core and the harmonics of electromagnetic forces. As the first stage of research to estimate the natural frequencies of the stator core pressed into the motor frame, the dual rings were chosen as the object of studies. They are similar to the motor in construction and are easy to use to solve the problems. The purpose of this study is to investigate the effects of the tight fit to the natural frequencies. The dual ring with several kinds of interference were made by shrinkage fit and natural frequency and mode were measured up to 20 kHz. It was confirmed that lower contact pressure provided large reduction ratio of natural frequency. Then, reduction at higher mode were theoretically analyzed.

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Vibratory Rate Gyroscopes have a number of advantages, such as simple structure, stoutness, longlife and quick response, owing to the mechanism of the vibrating body and the absence of the bearings by comparison with the conventional rotating wheel gyro, and are available for a low price angular velocity sensor. However, Coriolis'force with the lower range of angular velocity for sensing is very small, much more the torsional vibration of the suspension mechanism for sensing. Therefore, this paper discribes an experimental study of the mechanical fine tuning for making the higher gain about twin resonance tuning-fork type gyro, and reports on the method of obtaining the resonance to which the torsional vibration system is stabilized.

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A hybrid experimental method, in which a vibration experiment using an actuator and a vibration analysis using a computer are simultaneously conducted by exchanging information with each other, is being developed as a new seismic experimental method for structural systems. We have proposed using a shaking table as the actuator so that the hybrid experimental method can be applied to a secondary structural system attached to a primary structural system, and we have made an experimental system consisting of a small shaking table and a digital signal processor. In the work described in this report, this experimental system was applied to a single-degree-of-freedom secondary structural system attached to a primary structural system, the feasibility of this seismic experiment was demonstrated by comparing the results obtained from the hybrid experiment with those obtained from analysis of the whole structural system.

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A numerical method for analyzing free vibrations of twisted thin conical shell panels is presented based on the Rayleight-Ritz procedure. To this end, exact strain-displacement relationships are derived by employing the thin shell theory and the principle of virtual work for free vibrations is formulated. Algebraic polynomials are used as assumed displacement functions in the analysis. Frequency parameters are analyzed for typical conical shell panels and effects of variation of the curvature of the shell and of pretwist on them are discussed. Resonance frequencies and modes of vibration obtained experimentally are compared with analytical ones. The agreement between them is found to be quite good.

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This paper presents the study on the free flexural vibration of a complete elliptical plate with clamped edge according to the Mindlin's theory including the effect of shear deformation and rotary inertia. The analysis is rigorously made by the use of the Mathieu function and modified Mathieu function which are the solutions of the equation of motion expressed in terms of the elliptical coordinates. The frequency equation is derived by-applying the orthogonality of the Mathieu function. The eigenfrequencies calculated numerically are given in tables and figures for a variety of ratios of the minor axial length to the thickness and of the major axial length to the minor axial one. It can be seen that the calculated results approach to the ones due to the classical theory neglecting the effect of shear deformation and rotary inertia with decreasing thickness.

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In order to reduce the longitudinal vibration of a pipe string for mining manganese nodules from deep sea floors, the pipe string is supported by a linear spring at its upper part. Furthermore, a vibration absorber is attached to the buffer at the lower end of the string. The analyses of the longitudinal vibration and axial stress produced in the string indicate that the mutual effect of the spring support and absorber is very small on the peak amplitude of the longitudinal vibration of the pipe string but considerably large on the maximum axial stress induced in the string. The effect on the stress, moreover, is found to increases with the stiffness of the support. Thus, it can be said that the spring support of the pipe string combined with the effect of the vibration absorber attached to the buffer is a quite useful measure for reducing the stress induced in the pipe string by the vibration.

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This paper proposes a method to calculate the static and dynamic characteristics of the parallel-grooved stator/smooth rotor and the smooth stator/parallel-grooved rotor seals used in turbopumps. In this analysis, the calculation domain is divided into three control volumes which are two clearance flows in land parts and groove parts and a groove flow in groove parts. The governing equations for two clearance flows are derived using continuity and momentum equations. These equations are solved numerically by using the perturbation method. The fluid force in each part is determined by integrating the perturbation pressure distributions in the axial and circumferential directions. The total dynamic seal force is determined by summing up the dynamic forces in each part. The calculated results are compared with the experimental results.

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A new type of hybrid magnetic bearing which can control Cardan angle of rotor is proposed. It is intended to stabilize a flexible rotor which runs over the bending critical speed. Both ends of rotor is supported by the proposed magnetic bearings which are controlled by digital PD controller. Central displacement and Cardan angle of rotor is calculated by summation and subtraction of the measured displacements. These two quantities are put into the individual PD controller to get the actuating signals. To confirm the proposed technique a flexible rotor is made. In this paper, one end is supported by the proposed magnetic bearing, while the other end is supported by ball bearing. The theoretical and experimental results are showing high possibility of reducing the lower bending vibration.

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We discuss a method for combining each response excited by horizontal and vertical earthquakes in response spectrum analysis. In this report, we treated a single-degree-of-freedom system subjected to horizontal and vertical excitations, which represents one of the vibration modes obtained from the modal analysis of a multiple degree of freedom system. We proposed a method to combine the responses caused by horizontal and vertical excitations using a correlation coefficient between two responses and also proposed a method to evaluate the correlation coefficient by means of the power spectra of the two excitations and the frequency response function of the system under consideration. For verification of the proposed method, we conducted response combination for several earthquakes not only with the proposed method but also with the time history analysis. By comparing the two results, we showed that the proposed methods are useful.

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In this paper, the effect of environmental temperature on the damping properties of an oil damper is discussed. The oil damper can broadly be classified into two groups according to the generating mechanism of damping: viscous and nonviscous dampers. The viscous oil damper is a linear dashpot, whose damping is proportional to both the viscosity of oil and the velocity of vibrating members (usually piston). Whereas, the nonviscous oil damper is non-linear damper, whose damping is proportional to the density of oil and the velocity squared of the piston. Most of oil dampers are designed as a nonviscous damper, because it is considered that the damping force of the nonviscous oil damper is less dependent on the environmental temperature. We carefully examine the dependence of the damping force of the nonviscous oil damper on temperature. The experimental result shows that the dependence of the damping on the temperature is fairly large when the damper is driven at low velocity condition.

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The goal of this study is to develop a new light weight vibration control device which can suppress undesirable vibration of a building floor effectively. To attain this goal, the control system should be compact and needs to suppress vibration up to a high frequency. In this study, a new active mass damper (AMD) system is proposed, using an electromagnetic actuator. The control algorithm is based on model matching and disturbance observer principles. The effectiveness of the proposed system is verified by experiments.

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In order to achieve vibration isolation and reduction for a multi-degrees of freedom system, this paper develops the ON-OFF control that has been proposed on the single-degree-of-freedom system by the authors. The method introduces additional spring and mass system, and the additional mass is designed to control the clamping friction force by the brake mechanism. The non-linear control law for the single-degree-of-freedom system is applied to a multi-degrees-of-freedom system by incorporating the idea of the independent modal space control (IMSC) method. Numerical simulations and experiments demonstrate the effectiveness of the method.

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This paper describes a new method for high accurate mass measurement under vibration-like moving conditions. Although there exist research works on the mass measurement under vibration-like moving conditions, the effect of mass center of the weighed object is not taken into account in these researches. However, the influence of vibration-like movement, e.g. heaving, pitching, rolling, swinging, etc., on the measured value depends on the position of mass center of the weighed object. Therefore, the measured value obtained only by using the information of the vibration-like movement may not show sufficient accuracy. The authors propose a new method that measures a mass value considering both the information of vibration-like movement and that of the position of mass center of the weighed object. A mass measuring system to be treated in this paper consists of the weighing loadcell and several dummy loadcells, that are installed for getting the information both of the position of mass center of the weighed object and of vibration-like moving conditions. The effectiveness of the proposed measuring method is verified both by simulation and by a fundamental experiment.

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Analytical and simplified method was developed for predicting error propagation encountered in measuring head-to-medium spacing in magnetic disk drives. Two kinds of optical interferences observed between the flying head and the glass disk replaced with the magnetic disk were considered: One is the homodyne interferometry wherein the spacing is obtained from light intensity variation due to the interference. The other is the polarization interferometry in which the spacing is determined through phase difference between the parallel and perpendicular components of polarized light. To analytically predict the amount of error propagation, the detected signal is essential to be presented as the functions of its maximum or minimum value that determine the calibration curve. For this purpose, two kinds of accurate and useful approximations were introduced for the homodyne interferometry and for the polarization interferometry, respectively. Using these approximations, the calibration curves were presented as the functions of the detected signal and its extremum. Calculation examples were demonstrated for typical head-medium interface conditions and contribution of error components to the error in measured spacing was clarified.

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A machine and structure reduce their own strength by the cumulative damage caused by fatigue generated by dynamic loads. If the signals caused by the development of crack in materials are able to be detected, the condition of health of a machine and structure will be monitored to prevent the sudden fracture of them. It was reported by authors that the signals of that can be detected by the wavelet transform of the observed signals such as displacement, velocity and acceleration etc, because the wavelet transform can detect the discontinuity in signals. However, the wavelet transform require the computed time for its transform and then it cannot be used for on-line monitoring. Then, it has been strongly desired to detect the discontinuity in signal of acceleration and then, the jerk sensor composed by a vibratory gyroscope and a cantilever has been developed for this purpose. The proposed sensor is manufactured and used for the experiment, which prove the availabilty of this proposed sensor.

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We present a method of route selection for a vision guided mobile robot with an odometry system when the map uncertainty is given. The robot first generates candidate routes, which are expanded to possible loci in consideration of the map uncertainty. It then makes an observation and movement plan along each locus and computes the minimum traveling time. Uncertainties of movement and visual sensing are considered in this step. Finally, for each candidate route, the robot computes its expected traveling time from the traveling times along the possible loci and their probabilities. It selects the route with the least expected traveling time as the optimal route. The advantage of the planning method is that the observation and movement planning is incorporated in path planning to obtain the optimal plan. The three sources of uncertainty are considered in a unified manner in our method. The method has been implemented and tested to validate our claim.

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A multimodal teaching advisor (MTA) has been developed for sensor enhanced robotic systems used in manufacturing. The MTA utilizes the work-site operator's know-how and the robotic-systems information, including that from sensors, in a complementary manner. This system integrates information from various sources to carry out robotic tasks and presents this information through user interfaces that are easily understood by the operator. That is, the system integrates task specifications including tolerances, system constraints, sensory information, and operator-and robot-related information. The synthesized information is then presented in realtime to the operator at the work-site through a mobile multimodal interface. Experimental results show that this system can significantly improve total robotic system performance by ensuring a high quality teaching task.

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We have developing an intelligent mobile robot for service use which can be utilized as a "secretary or helper robot" during the day and "security guard or maintenance including floor-cleaning robot" at night in office buildings. When the service robot works or moves autonomously in an enviromnent including human beings, it should be able to recognize its environment on real time. In this paper, new biological object extraction method is developed. In order to extract objects from a frame image taken by a camera, many Virtual Flies (VFs) scattered in the CRT display are utilized. An individual VF composed of 3×3 pixels can freely fly in the display. Fundamental object extraction method is to detect objects just like flies sensing foods and swarming around them. Methodology and experimental results together with its application of Hand-Eye system using a robot manipulator are described in detail.

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This paper presents a simple design method of a digital control system for a flexible arm. First, we derive the new discrete time flexible arm model directly, without using an approximation to lumped parameter system. Next, based on this model, the digital control systems are designed. The control algorithms can be implemented without considering the spillover problems and in very simple formulation. Then, we apply it to control a cantilever beam. Simulation and experimented results demonstrate the effectiveness of the proposed discrete-time model and show its advantages in control applications.

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Sliding mode control theory is nonlinear robust control theory and one of variable structure control. This theory has good performance against uncertainty satisfied matching condition. But the conventional sliding mode control system often becomes unstabled due to high frequency vibration caused by unmodelled dynamics. In this paper, we consider application of Frequensy-Shaped Sliding Mode Control (FSSMC) to flexible structure. Flexible structure has uncertainty on the control input side, e.g. time delay, friction, and so on. It is difficult for control of flexible structure because of these uncertainty, when we applied a linear control. Applying sliding mode conrol, we can design a eternal system against these uncertainty and dynamics for sake of mating condition satisfied. Moreover, closed loop system does not become unstabled due to ummodelled dynamics for sake of robust hyperplane designed using H_∞ theory. For example of application, we have just applied to the fiexible truss structure with control momentam gyro (CMG). We have verified from simulation and experiment that this method has good performance.

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This paper describes the dynamic characteristics of the mechanism with a harmonic speed reducer and its precision rotational positioning. The harmonic speed reducer is the reduction gear which is often used for precision robots because they can be made very compact and lightweight without backlash. However they have the friction and the low stiffness which make the positioning performance low. The purpose of this research is to clarify the suitable control method for the rotational positioning mechanism with the gearing and to realize high speed and high precision rotational positioning over a wide range. For this purpose, first, the characteristics of the mechanism are examined experimentally. The experimental results show that the mechanism can be represented by two kinds of models, that is macrodynamic and microdynamic models. Then, by using the controller including disturbance observer, the mechanism has the positioning accuracy better than 1" on the working range more than 4.0×10⁵".

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Intelligent monitoring and control system for cylindrical grinding process was developed based on the sensor fusion technology utilizing an acoustic emission sensor, a power sensor and an inprocess gauge. Grinding wheel life defined by the surface roughness deterioration and the chatter vibration was automatically determined through the developed system. The grinding cycle having a rapid infeed and retraction was automatically minimized after several test grinding by proposed algorithms. In addition, user friendly human machine interface was developed to make the system more practical one.

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A non-circular fine boring machine for piston pin bores has been developed in this research. The devoloped boring machine uses a magnetic bearing spindle with a hybrid controller. The hybrid controller consists of a conventional PID analogue controller and a digital controller. The PID controller is used for stabilizing the magnetic bearing system. The digital controller, consisting of a personal computer, an A/D converter and four D/A converters, is used for controlling the trajectory of the cutting tool in non-circular machining of piston pin bores. The periodic learning control with inverse transfer function is applied to get the desired non-circular profile of piston pin bore. Several cutting tests are carried out for a non-circular piston pin bore at a rotational speed of 25 rps (1500 rpm). The difference between the reference profile and the cutting profile was within 2 μm.

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This paper proposes a system, which manages both efficiency and flexibility in the manufacturing system. It has been considered that a autonomous distributed system is superior to a centralized system in terms of fail-proof, expansion, load dispersion, flexibility, and the possibility of the evolution. However, it is difficult to manage both efficiency and flexibility according to conventional method in a autonomous distributed system. To solve the problem, we propose a method, where the carrier organizes the whole number of the carrier in the system, according to the volume of the task and the complexity of it. Also we evaluate the proposed method of self-organizing behavior by a multi-AGV autonomous system in the quantitative dynamic environment. It is shown that the system exhibits higher efficiency compared with the centralized system by introducing self-organizing in the quantitative dynamic environment.

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Our aim is to develop a microactuator to be used for endoscopic surgery. The purpose of this study was to construct cylinder-piston-type microactuators that are actuated by phase transition of material. We use a paraffin as the working material because paraffin has a large coefficient of expansion due to the phase transition in the temperature range of 35 to 45 degrees of centigrade. Firstly, we made a microactuator whose outer diameter was 1.5 mm and the length was 65 mm. The actuator generates the stroke of 2 mm against the load of 1 kg. Secondly, a micro-scissors was attached to the piston of the actuator. It was confirmed that the micro-scissors can cut the paper, string and rubber tube without any trouble. The operation time for one cycle of cutting was approximately 13 secondns.

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This paper deals with the power assist system which is used to attenuate load force. We have proposed the control method for avoiding actuator's saturation and maintaining high power assist efficiency. The proposed control method is based on that, the operated load is divided into gravity load and dynamic load, and the power assist ratio for the gravity load is determined considering the human capability and the ratio for the dynamic load is determined considering the actuator's maximum torque. In this paper, we discuss how to apply the control method to a multi-degree-of-freedom power assist system. The relation between an operator's force and a load force to realize the proposed control method in the multi-degree-of-freedom system is formulated, the controller is constructed based on it, and the effectiveness of the power assist system used such controller is confirmed by experiments using a multi-axis power assist system.

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Sensors utilized for diagnosing the flame current of a flame-detector, for instance, are limited because the burner of the absorption chiller is small or medium in size. Subtle differences in the conditions can affect the readings of these sensors and make them unstable. The knowledge of burner daignosis based on such unstable sensors has several features. 1. The structure of the knowledge is relatively simple. 2. The knowledge is probabilistic because of the unstable readings and the non-deterministic nature of the knowledge possessed by engineers in the domain 3. The knowledge has a low quantitative accuracy. In this paper, we propose a system that employs simple binary logic to determine failure modes, and probalistic multi-valued logic to evaluate the probabilities of failure causes. This system achieves suitable expressions for knowledge of domain-engineers and features a compact inference engine that can be implemented into small-size computers such as a notebook-PCs.

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In scientific visualization, displaying numerical data using realistic image is essential to recognize physical phenomena effectively. In this paper, a visualization method using photograph image was proposed. By relating the analysis model that is used in the numerical simulation to the shape model and the photograph imege, the warped image is generated in real-time according to the results of the numerical simulation. This method was applied to the visualization of scientific data such as an earthquake response analysis and a deformation analysis. As results, realistic images were generated to visualize data in real-time. In addition, the distortion of the generated image that depends on the rotation or the deformation of the displayed objects was evaluated. This distortion can be decreased by increasing the number of the control points for the warping of the photograph image.

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Lateral trajectory and crosswind sensitivity with fixed control steering are often applied in evaluating for crosswind conditions. These indices, however, don't always represent the delicate feeling on steering correction. In this paper, a stability criteria of driver-vehicle system is derived analytically for straight running against crosswind, and then the quadratic form of state variables for handling performance is proposed as an active crosswind sensitivity, in order to evaluate objectively handling performance against wind gust and to optimize many design parameters as well as aero-dynamics.

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This paper presents the traction force control of an electric vehicle using fuzzy reasoning. The electric vehicle is in a wheel-in-motor system, and the yaw moment is regulated by the traction force control on front and rear wheels and on left and right wheels (F/R & L/R TC). The traction force control is determined by using fuzzy reasoning where the slip ratio, the error of yaw rate and the change in the error of yaw rate are denoted as the input variables of the fuzzy control rules for left and right wheels, and the yaw rate and the error of yaw rate done as those for front and rear wheels. Comparing the simulation result obtained from the proposed method with that obtained from the traction force control only on left and right wheels (L/R TC), the former indicates more improved performance than the latter in handling and stability of the vehicle.

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When a road vehicle makes a turn on a rough road, road disturbance causes fluctuation of vertical load, which results in deteriorated vehicle maneuverability and stability. In the previous study, the authors investigated that the attitude control with additional vertical load control by active suspension was effective to improve vehicle stability in cornering on uneven road surface by using half car model formed from the combination of vertical and lateral motions. In this case, both motions were treated as independent from each other in order to explain the dynamic characteristics. However, considering an actual 4 wheeled vehicle, vertical and lateral motions are not independent due to roll motion. In this paper, by using 4 wheeled full car model which has nine degrees of freedom, the responses of vertical and lateral motions of vehicle body are discussed. And the effect of vertical load control on vehicle stability is verified.

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Recently, the vehicle which is adopting an electronically controlled throttle valve (ECTV) is controlled by DBW (Drive by wire) for the purpose of improving the automobiles performance. One of them is an optionally tuning for the accelerator pedal sensitivity, and it needs axle output torque as the feedback signal. Because the cost of hardware torque meter is the practical problem, the axle output torque should be estimated by adaptive observer with table-looking method. If the disturbance load torque by a slope of road and so on is not already known, observer can not be used. Therefore the disturbance load torque should be estimated without sensor also. Expected observation and control results are obtained by using the simulation which is identified with an experimental device.

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Contact geometry between a wheelset and track is a fundamental problem of railway vehicle dynamics. This paper scrutinizes two dimensional contact geometry. Firstly, the independent variable of the contact geometry is investigated. It is shown that the roll displacement of a wheelset is superior to the lateral displacement as an independent variable especially in flange-contact area. Secondly, minimum-value search for the contact problem is investigated. It is shown that the gradient method is superior to the displacement method from the view point of calculation time. As an application of the algorithms, contact geometry on switch track, which is important in view of safety, is calculated for worn profiles as well as designed profiles.

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In this paper, three dimensional contact geometry for measured profiles are studied. Three dimensional contact geometry requires the accuracy of profile data. But measured profiles contain measuring errors. In order to filter the errors, template method is proposed. The method uses the flange-ware function and reduces the error without changing the profiles. As an application of the method above, three dimensional contact geometry of worn profiles on a tight curve is calculated. Contact points, rolling radius differences and other geometric parameters are calculated when a wheelset moves in yaw direction. Geometric characteristics of a worn wheelset with attack angles on worn track in a tight curve are discussed precisely.

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A mathematical model was developed for the mobility simulation of tracked vehicles on non-level terrain. The motion of the vehicle is represented by three translational and three rotational degrees of freedom. The soil-track interaction model is based upon available soil plasticity theories and terrain, in this code, as described by a discretized surface elevation map. Terrain-vehicle interaction was developed by a set of generalized constitutive relations between the interaction forces and vehicle kinematic variables, such as sinkage and slip velocity. The turning tests by using a scale model on dry loose sand was conducted. The numerical results were compared with experimental data.

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In this paper, steady characteristics of the torque and the current density of rotating disk type devices using ERF with smectite particles were investigated experimentally in detail for the purpose of engineering designing. We measured them under the various experimental conditions of the dimension of the device, the electric field strength, the temperature, and etc.. In addition, power of the device was estimated from the data of the rotating moment and the input electric power to the device. As a result, we clarified the effect of the experimental factors on their steady characteristics. On the other hand, we clarified the difference between the disk type devices and the concentric cylinder as another type of device.

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The purpose of this study are to ensure reliability of the power transmission gears, and to predict operating condition of high speed gears especially with regard to temperature distribution in teeth and blanks. The experiments were carried out using power circulating gear testing machine (1100 kW) under ultra high pitch line velocity (∼150 m/s) and temperature distribution in teeth and blanks were measured. By the experiments, the following facts are known. By increasing line velocity, the temperature of teeth increase parabolically and the distribution of bending stress become nonuniform along face width.

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To reduce the size of reduction gears where big power is transmitted through crossed shafts, it is necessary to increase rotational speed and decrease the transmitted torque and load. To know dynamic behaviour of high speed bevel gears, the experiments were carried out and tooth root stress and temperature were measured. Also a spiral bevel gear set analysis has been developed that makes use of mesh stiffness calculations based on finite-element methods. The analysis enables the calculation of dynamic loads. And then, the following results were obtained. (1) A power absorbing gear testing machine (960 kW) could be operated up to high pitch line velocity (∼110 m/s) and it is found that dynamic loads is nine times as much as static loads under the condition of 110 m/s. (2) Analytical results of dynamic load agreed with the experimental results. It was confirmed that the analytical method has practical accuracy and usefulness.

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When a path of contact and its contact normals of a gear pair which has symmetrical convex tooth surfaces (elastic) modified slightly from true involute helicoids for one member and the conjugate surfaces (rigid) of the true involute helicolds for the other are given under load as functions of angle of rotation, the equations of motion are solved to obtain the dynamic incremental loads algebraically. The equations of motion of all kinds of gear pairs having modified involute helicoids like mentioned above are expressed by the same ones which have been already obtained for the involute helical gears with the modified tooth surfaces. So that the solution, namely the dynamic incremental loads are also expressed the same from cylindrical to hypoid gears. The variation of bearing loads is calculated, which consists of both the dynamic incremental loads and the fluctuation of the static load that is generated by the wrong selection of the path of contact.

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In order to obtain the fundamental data of surface failure and surface durability of ion-nitrided sintered powder metal gear, the sintered rollers, which had two kinds of diameters 30 and 60 mm, and three kinds of hardened depth, were fatigue-tested under a sliding-rolling contact condition. The failure mode of all rollers was spalling due to subsurface cracks propagating parallel to the roller surface. The surface durability of the roller increased as the relative radius of curvature decreased and the hardened depth increased. The experimental results were discussed by the amplitude of the ratio of shear stress to Vickers hardness. The minimum occurring depth of the spalling agreed almost with the depth of peak amplitude of the ratio of orthogonal shear stress to Vickers hardness. The occurring depth of spalling became deeper as the relative radius of curvature increased. The hardness distribution influenced greatly the surface durability of ion-nitrided sintered powder metal rollers.

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The measurement of an involute pinion-type cutter by CNC gear-measuring machine is newly developed. In this method, a pinion-type cutter is regarded as a conical involute gear. The conical involute gear can be measured as a helical involute gear by introducing "equivalent helical gear" concept. Thus, the tooth surface of the involute pinion-type cutter can be measured as the tooth surface of the helical involute gear by CNC gear-measuring machine. Experiments demonstrate that this method gives accurate results and has practical utillity. Finally, tooth surface analysis of the pinion-type cutter is also presented.

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Hydro dynamic Lubrication analysis of floating bush bearing considering oil supply pressure is important for reducing friction loss or vibration of turbocharger. in this paper, hydro-static pressure and oil flow in the floating bush bearing due to high pressurized oil supply are investigated. From three dimensional flow calculation, it is found that static pressure is transferred not only to outer film but also to inner film through bush hole, and that the amount of static pressure in inner and outer film is force which push shaft and bush to opposite side of oil supply hole. In addition, it is clarified that influence of bush hole position on the static force and the oil flow is small enough to ignore. These calculation result has been verified by the experiment. Furthermore, based on the linearity of flow in the bearing and the independence between inner and outer film, it is shown that 2 D flow calculation of Reynold's equation considering pressure boundary condition of oil supply can approximate 3 D flow calculation results for simplicity.

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In this paper, influence of oil supply pressure on steady-state characteristics in floating bush bearing used for turbocharger is investigated by theoretical calculation using Reynold's equation. Steady-state properties are calculated by performing load and friction torque balance between inner oil film and outer oil film of bush, and oil temperature equilibrium. As the calculational results, the follows have been found about the effects of higher pressure oil supply, (1) eccentricity ratio and oil flow increase in both inner and outer oil film, (2) temperature raise due to friction heat of inner film is suppressed because of oil flow increase, (3) due to superposition of hydro-static and hydro-dynamic pressure, there is no oil film area where pressure is zero. Furthermore, these calculational results have been verified by experiments, and for example of design use, the developed calculation method has been applied to investigation of the relation between bearing clearance and steady-state properties.

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Both experimental and numerical studies are conducted on half-frequency whirl (HFW) stability of axially-grooved self-acting gas-lubricated journal bearings. The studies demonstrate that 8-grooved bearings are unconditionally unstable with usual bearing clearance and rotational speed. On the other hand, 2 grooved bearings operate stably at relatively low values of bearing number which are obtained with usual clearance and speed. The physics of HFW stability is attributed to the pressure distribution geometry. Further, as a result of extensive numerical simulations, it is found that 3 grooved bearings with groove width ratio to total width of 0.3 through 0.5 give favorable stability performance.

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In this paper, we investigated the influence of slip velocity on the characteristics of an externally pressurized annular porous gas thrust bearing, which has a thin restricted surface layer. From numerical calculation, it is found that the slip velocity increases flow rate and decreases load capacity. It is also found that the static characteristics can be easily calculated from those of the case without slip velocity. In the range of practically used porous feeding parameter, the slip velocity increases dynamic stiffness at low and moderate squeeze numbers and decreases dynamic stiffness at high squeeze numbers. It decreases positive extreme value of damping and damping ratio at high squeeze number. The influence of slip velocity on dynamic characteristics becomes significant when the porous surface is restricted strongly. This means that the influence of slip velocity should be considered in designing a bearing when the dynamic characteristics is important.

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This paper describes a method to evaluate an equilibrium thin, air film space between head sliders and rotating disks on megnetic disk files. The exact evaluation of the ultra thin air-film equilibrium is very important for the design of a floating head slider. The space of the slider is supported by hydrodynamic pressure and it has a strong nonlinearity. The equilibrium space is related to the woking load of the slider and rotating disk speed. When slider shapes are complicated, or when the slider is running with a yaw angle, or when running speed differences of the slider need to be considered further, an exact evaluation of space is very difficult. The method used in this study gives successfull evaluations for these cases. The method uses less time for one iteration cycle and less iterations than the conventional method.

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With the development of micro fabrication, single crystal silicon has been used in many microelements such as micromachines. The aim of this research is to clarify the microtribological properties of single crystal silicon to improve their characteristics by silicondioxide overcoat. The specimen used in this experiment is single crystal silicon of (100) and with a overcoat of silicondioxide. Thickness of silicondioxide is 988 nm and 94.7 nm which is coated by plasma CVD method. In this experiment, frictional force between diamond stylus tip (radius of curvature 2 μm and 10 μm) and the surface of single crystal silicon and micro hardness are measured by using scratch tester and dynamic hardness tester. In this paper we show the results of micro friction characteristics of single crystal silicon by silicondioxide overcoat.

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