The collision force in a tumbling ball mill was analyzed numemically by discrete element method(DEM). From the frequency distribution of the collision force obtained by the present numerical simulation, the selection and the distribution functions to predict the grinding rate were evaluated. In case of constant rotational speed, the selection functions were almost the same except for the case of the ball filling ratio of 0.1. On the other hand, the selection functions were strongly affected by the rotational speed of the mill vessel in the case of the constant ball filling ratio. The distribution functions showed no significant difference in all conditions. Both functions derived by the present simulation were compared with those obtained from the grinding experiment with measurement of collision energy between the ball and mill wall without powder. The simulated selection and distribution functions were in good agreement with those obtained from the grinding experimental results.

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This paper describes experimental and analytical investigation on an asymmetric top with three legs(called "oscillatable-rotor")which shows a preference for rotation in one direction. Motion starting with a given initial zenith angle has been experimentally observed to evaluate the characteristics of the oscillatable-rotor. It has been clarified that the oscillatable-rotor transforms oscillation induced by initial potential energy to counterclockwise rotation. Analytical results based on a rigid body model of the oscillatable-rotor agree well with experimental results not only qualitatively but also quantitatively. The mechanism of motion transformation is also discussed.

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The finite difference method is applied to calculate non-Gaussian probability density function of a single DOF degrading hysteretic system subjected to white noise excitation. Wen's degrading hysteretic model is used in this report, where the degrading parameters are time varying and expressed by linear function of dissipated energy. The probability density function of teh response is governed by linear partial differential equation known as the Fokker-Planck equation. To analyze this equation numerically, we use the finite difference method that is modified in the previous reports to satisfy fundamental properties of probability density, i.e., probability density is non negative and total probability equals to one. Transient moments and probability density of a single DOF degrading hysteretic system are calculated and compared with the MCS results. The response characteristics of degrading hysteretic system are also considered.

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A kind of shooting method is presented for determining the periodic solutions with high accuracy of piecewise linear systems with strong nonlinearities. This method is composed of analytical solution of each linear equation of motion and Newton-Raphson method. The periodic solution obtained by this method correspond to exact solution. This method is applied to preloaded compliance system, two-degree-of-freedom gear rattling system and multi-degree-of-freedom system with nonlinear dynamic absorber. The results of this method and those of the ordinary shooting method which uses Runge-Kutta-Gill method as numerical integration method are compared with each other. The results obtained are summarized as follows : This method has high cost performance, namely it converges to highly accurate periodic solution in much shorter time than the ordinary shooting method. Moreover, its time difference becomes larger with increasing the degrees of freedom of the system. The complicate higher harmonic vibration which occurs in geared system is also obtainable by this method.

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This paper deals with chatter vibrations of an automotive wiper with one arm. First, an experimental apparatus which simulates the wiper is made. Using the apparatus, friction characteristics between the rubber blade and the glass disk are investigated. Next, the chatter vibrations are examined experimentally. It is found that in a certain region of disk speeds two types of steady state motion are observed : one is chatter vibration and the other is stable equilibrium. Regarding the experimental system as a single-degree-of freedom system, we derive the equations of motion. Solving it, we found that the motion observed experimentally is confirmed to occur. Also we found that a jump is observed in the amplitude of the vibration characteristics, and that the jump is associated with sub-critical Hopf bifurcation. Finally, the effects of parameters consisting of the friction characteristics on the vibration characteristics are evaluated numerically. It is found that the sub-critical Hopf bifurcation is influenced by cubic non-linearity of the friction characteristics.

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This paper describes nonlinear vibration and control of a vibratory machine which has a large work mass. Vibration of the vibratory machine and movement of the work are coupled through normal force and friction force. The coupled vibration is nonlinear, and a resonance curve in small excited voltage has a peak in low frequency region and a resonance curve in large excited voltage has a peak in high frequency region. Transportation velocity property shows the same tendency. Driving system of the vibratory machine using self-excited vibration follows the resonance frequency change automatically, and it improves machine efficiency. Amplitude constant control of self-excited vibration pulls up the upper limits of vibration amplitude and transportation velocity. Amplitude control using variable feedback gain starts up self-excited vibration quickly, and the vibration will not contain any higher-harmonic components, which make some noise.

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We consider a shape optimization problem for a cantilevered pipe conveying fluid. The pipe is controlled actively by LQG controller which is synthesized for a mathematical model of the pipe system in a specified flow velocity. The outer diameter distribution of the pipe and the location of the sensor and the actuator are optimized such that the critical flow velocity of the closed-loop system is maximized. The outer diameter distribution is optimized such that the total volume of the pipe is nuchanged with the initial diameter distribution. This optimal design problem results in a maximization problem with an equality constraint. Since the critical flow velocity of the closed-loop system may not be continuous for each design parameter, we can not utilize a gradient information of the objective function. In this paper, we use SA(simulated annealing)method which is known as one of discrete optimization techniques.

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This paper proposes a design method for vibration control of a structure with an active dynamic vibration absorber involving actuator constraints. We formulate the linear parameter varying system taking into account both the maximum control input and the maximum stroke of the actuator by using a nonlinear function of hyperbolic tangent. The gain-scheduled control based on the linear matrix inequality is obtained so that the closed-loop system is stable and has good performance even if saturation phenomena of the actuator occur. By simulations we verify that the proposed method is useful for not only an impulsive input but also a non-stationary random input such as earthquakes.

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We experienced unusual acoustic vibration in the operation of in-line array tubular heat exchangers named gas heater. This vibration mode was not one dimensional in the direction perpendicular to gas flow and could not be vanished by inserting baffle plates into the tube bundle along the gas flow. So we had to confirm acoustic vibration characteristics using 3-dimensional air flow scale model. Here, we report this test results about multi-stage gas heater and some countermeasure methods. Especially we discovered that unusual acoustic vibration mentioned above did not appeared in the case of some staggerd tube array having same heat transfer characteristics as in-line tube array.

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This paper focuses on the development of the suspensions for the flywheel energy storage systems on road vehicles. The flywheel energy storage systems are commonly known as flywheel batteries. The flywheel batteries can be applied to the energy buffer of the electrical vehicles. There are, however, several problems for applying the flywheel batteries to the vehicles. The gyro dynamics, which increases the loads on the rotor support bearing and expands the occupied space of the flywheel battery, is one of these problems. Therefore, the development of the suspension systems which decreases the influence of the gyro dynamics is valid for applying the flywheel batteries to the vehicles. This paper reveals the suspension system that is composed of the gimbal, the actuator and the gain scheduling controller. To confirm the validity of this system, simulations and experiments are carried out. These results show that the system revealed in this paper can decrease the influence of the gyro dynamics.

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For the vibration suppression of flexible continuous systems, an I-shaped impact damper with parallel linear spring and dashpot is first proposed. And, as laboratory models, a beam and a L-shaped panel to which teflon and multiple impactors are installed are considered, and the equation of motion of those systems are formulated by the finite element method. Concerning the free vibration and the forced vibrations by harmonic and random excitations for those models, the results of numerical simulation and those of experiments are compared, and it shows the validity of theoretical modeling and the usefulness of the proposed I-shaped impact damper. Finally, on the ground of the theoretical analysis for the case of random excitation by band-limited white-noise, the basic examination of the multi-modes vibration suppression effects by multiple impact dampers is carried out.

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This paper describes the feasibility study on vibration suppression by attaching two rotating arms to a torsionally vibrating body, which is suspended by cables. The effects of angular velocities and phase angles of rotating arms to the vibrating body on vibration suppression are examined. Accordingly, it is clarified experimentally and theoretically that torsional vibration is quickly suppressed by using the rotating arms.

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A low order modeling methodology and a reduced order output feedback control algorithm for suppressing the vibration and obtaining the high speed, high precision positioning of flexible robot are presented and discussed. The low order modeling methodology gives no modal truncation error and make it possible to vary the mode shapes of the link according to the change of the boundary conditions due to the feedback gains and the payload at the tip of the arm. The reduced order output feedback sliding mode control algorithm is designed by the combination of sliding mode controller and suboptimal output feedback controller so as to achieve both the damping of the system vigration and the stabilization at the same time. According to the presented method, the vibration suppression control of the two-link robot arm is realized by only 6 sensors, that is, this robot arm model is reduced to 6 output and 2 control input noncollocated system in spite of 34 state variables system.

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Minimizing cycle time in manufacturing systems is a general requirement for improvement of productivity. Many of manufacturing machines are composed of multi-axes mechanical systems, in which each axis is controlled to synchronize with other axes to achieve given tasks. This paper proposes a method to generate an optimal trajectory command for such multi-axes mechanical systems, which minimizes the cycle time and satisfy constraints on trajectory tolerance to keep the synchronized motion. Based on an initially given trajectory command, the optimal command is generated by(1)scaling the time axis to obtain the optimal speed along the trajectory and(2)deforming the given trajectory command to compensate for the delay in a position servo of each axis. Simulation results for a 2 D.O.F robot manipulator are presented to show the effectiveness of the proposed method.

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Construction vehicle is widely used in construction works. Especialy in town area, a small-sized construction vehicle is often used, since it is usable in narrow place and low cost. However, the small-sized construction vehicle has characteristic problem of human hunting, and it make difficult to opereat. This paper deals with Human Hunting phenomena(HHP), which is one of the coupled vibration phenomena between the vehicle and the operator on board, appearing at the operation of the small-sized excavator and degrades operativity. This phenomena is related not only to the vehicle dynamical characteristic but also to human-operator's dynamical characteristic. To analize this phenomenon, it is necessary to consider the vehicle-operator dynamic model. We derived a mathematical model, which has six degrees of freedom to analyze this phenonmenon. Up and down motion of the excavator-boom is simurated. And it agrees with the phenomenon well. The linearized mathematical model shows that some control lever parameters are related to stability criterion. By simulation, it is confirmed that the proper selected control parameters can suppress the HHP.

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An Active suspension using an actuator has most superior performance. But it does not always fit common automobile because of its high energy consumption. Therefore it is necessary to study an active suspension which can operate by the low energy consumption and achieve the highly isolation vibration performance. To decrease energy consumption, we proposed a hybrid suspension consisting of a pneumatic cylinder as an actuator and a variable damper. Energy consumption of a hybrid suspension is lower than an active suspension and isolation vibration performance is higher than semi active suspension. And to obtain lower energy consumption suspension, we mainly operate active control in low frequency area and operate semi-active control in high frequency area by using same kind of frequency shaping filter. The performance of the proposed suspension system is discussed through experiments.

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In targeting the production process of the vulcanizing accelerator, a newly developed granulation control system is proposed for saving labor in the process and improving the quality of the product. The system is assembled referring to the expert's procedure for the regulation of the granulating state that is made up of two images about the shape of pellets and the state of the granulating machine. To cope with these tasks, the proposed system includes the following two independent feedback controls. The shape of pellets is regulated through an image processing and a combined estimation with a neural network and a fuzzy model. Similarly, the state of granulating machine is also regulated by using fuzzy inference. Through the examination of the experimental results concerning the accuracy of the models and the following of the assembled system, it is confirmed that the system proposed is useful for practical applications.

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This paper presents a method for robust model matching control of discrete-time systems in the presence of unmodeled dynamics. This scheme can robustly control the nominal model in the presence of unmodeled dynamics and achieve the desired model matching simultaneously. Furthermore, the sufficient condition for stabilizing the nominal model in the presence of unmodeled dynamics is derived and the existence of bounds for all signals is proved. Finally, computer simulation results are presented to show the effectiveness of the proposed method.

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This paper introduces a vector control of an induction type axial gap combined motor-bearing. The induction type motor has merits of large axial force control capability due to the flat magnetic property of the rotor. However it is difficult to control the axial force and the rotating torque independently. To solve this problem, a vector control is applied to the induction motor. The axial force and the motoring torque are analyzed theoretically and the independent control for them is developed. In order to confirm the proposed technique, an experimental motor has been made and tested. The theoretical analysis and experimental results confirm that the rotor is controlled stably and the rotating torque and the axial force are controlled independently by the proposed technique.

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Kinematic analysis and derivation of equations of motion of a mechanism with loops of different motion spaces are developed. First, it is shown that screw coordinates of a joint which expresses relative motion between two links must be expressed by the elements of a basis of motion spaces of the loop to which they belong. Then, it becomes possible to derive the same number of linear equations of joint velocities and accelerations for a loop as the dimension of its motion space and they can be determined by solving the linear equations. Next, it is described that the force analysis can be performed by expressing the joint wrench as a linear combination of elements of the basis of a motion space and other linearly independent screw coordinates. Using the theorem, the computational scheme for kinematic and force analysis is derived and the method to derive the equations of motion of a mechanism is also clarified.

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An electromagnetic actuator with magnetic fluid and elastic membrane is developed in this paper for laminar flow control. The actuator consists of a magnetic fluid layer, an elastic membrane and nine coils. The coils with 1600 turns of coated copper wire are used to generate magnetic field in the actuator. The elastic membrane is moved up and down by alternative magnetic field applied to the magnetic fluid layer, and the motion is used to control the transition of boundary layer from laminar flow to turbulent flow. The static and dynamic characteristics of the actuator, including displacement of elastic membrane and frequency response, were experimentally investigated. The effectiveness of the actuator in laminar flow control was shown by wind tunnel testing. The two-dimensional wave, or Tollmien-Schlichting wave(T-S wave), induced in boundary layer of a flat plate by a speaker was effectively attenuated by the developed actuator installed in the plate.

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We propose a strategy for cooperation of multiple PID position-controlled manipulators. Free joint mechanisms are installed at the tip of each manipulator to avoid excessive inner forces due to mutual positioning errors of manipulators. Since the cooperative system has kinematic redundancy due to additional passive joints for cooperation, a way to exploit the redundant degrees of freedom is proposed based on the kinematic analysis of the cooperative system. A cooperative mechanism consisting of four passive joints with electro-magnetic brakes is developed and the effectiveness of proposed algorithm is verified by experiments using two industrial robots.

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This paper describes an in-phase design method of Quasi-Rigid modes of swing-arm positioning-mechanism for high servo-band-width. Swing-arm is firstly assumed to be a rigid body that is supported with elastic pivot bearings. Position and number of driving-point are changed so that both of the lowest two natural modes of vibration move the same direction as the rigid body mode even when mass center of arm coincides with the pivot-coeter. The mode shape of the first bending vibration of arm is also considered at choice of position(s)of driving-point. Two types of positioning-mechanism, which are called BSAP and DESAP, are proposed. Frequency response function of proposed positioners is calculated with the Finite Element Method models in which elasticity of arm is considered. It is concluded that servo-band-width will increase by 25% or 60%.

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We have previously developed a navigation system for an autonomous mobile robot. It can find the landmarks on the ceiling to move and work. However, when the robot fails to recognize a landmark, the robot can not calculate self-position. So, the robot has to prepare for the behavior of error recovery. But an error that is not able to recover may occur. In such a case, the robot needs to relocate the self-position. In this paper, we define Global matching as the behavior that is able to relocate the self-position and proposed this module for the final module of error recovery in HALAS(Hierarchical Adaptive and Learning Architecture System)that have been proposed as Hierarchical System by us.

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In this paper, we describe a learning of fuzzy behavior-based control system by applying a virusevolutionary genetic algorithm with species. We first state the development of a virus-evolutionary genetic algorithm with species(VEGAS), in which one population is divided into some subpopulations(i.e., species)so that a virus infection between species can be introduced as well as a virus infection within a species. We then apply the VEGAS to the learning of a fuzzy behavior-based control system for a mobile robot with two independent driving wheels, where a control problem of acquiring multi-objective points is considered. The effectiveness of the present learning method is demonstrated by a set of computer simulations, compared to the conventional method with a simple GA.

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This paper describes a method of determining meat quality using the concepts of "marbling score"and texture analysis. The marbling score is a measure of the distribution density of fat in the rib-eye region. From the results of an investigation carried out by means of questionnaire put forth to graders, we consider the marbling of meat as a texture pattern and propose a method for the implementation of a grading system using a texture feature. In the system, we use a gray level cooccurrence matrix as a texture feature, which is typical second-order statistics of gray levels of a texture image, and make standard texture-feature vectors for each grade using it. The grade of an unevaluated image is determined by comparing the texture-feature vector of this unevaluated image with the standard texture-feature vectors. Experimental results show the proposed method to be effective.

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We experimentally analyzed the motion that human try to stop an object accelerated by gravity with his or her hand as smooth as possible. The trajectories of human hand motion observed in the experiments were reproducible and showed smooth profiles after the sufficient attempts. Changes in softness of human hand in the attempt were approximated by variable impedance model. The approximated changes of impedance parameters were divided into three phases, in which human changes his or her control modes. Moreover, human control performance was investigated from the view point of passivity. The results showed that the system was passive throughout the motion, and that the profiles of the passivity showed bell-shaped, which is peculiar to human smooth control performances.

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The authors have developed a tactile display that is attached to the user's fingertip. The display presents the touch status between the user's finger and a virtual spatial object by a vibratory stimulus. The display is equipped with ten vibrating pins, which are contacted to the surface of an index fingertip or a thumb. By changing the pattern of vibration, the display presents the geometrical features of an object surface such as a vertex, an edge, and a plane. An experiment was performed to confirm the user's discrimination between the patterns. A pick-and-place model task in a virtual space was also performed to reveal the effort of the tactile presentation during virtual object manipulation. The results showed that the tactile presentation improved the task completion time and the positional accuracy of the manipulated object.

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In order to realize the grasping mechanism of hand which grasps cylinder with lifting hand, the relationships between the optimum diameter of grasping cylinder and arches formed by fingers and palm was investigated. The optimum grasping diameter of the lifting hand was approximately 30 mm at no weighted condition, the diameter increase with increasing the lifting weight of pipes, then saturated about 40 mm at 30 N. It was found that the arches formed by a palm-forc fingers except for a thumb was more closely connected with the optimum grasping diameter than the arches formed by a thumb-a forefinger. From these results, in view of the arch formation, the grasping mechanism with lifting hand and it's weight dependence was discussed.

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Virtual reality technology has been widely applied in telerobotics, sports training and so on. In the present paper, we consider a virtual catch-ball as an application of virtual reality. The virtual catch-ball system has three subsystems ; they are a pitch-ball subsystem, a catch-ball subsystem and HMD(Head Mounted Display)system with 3D images. We develop a force display of which structure was very simple. In the force display, the force is realized by a spring. Using the developed force display the human force perceptive characteristic on hand is measured. The experimental results suggested that human perceptive sensitilvity of force is depended on the hand position and the presented force volume. From the results of experiment, some important points are suggested to realize a force display with high performance.

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This paper describes impedance characteristics of human finger joints. Five joints of thumb and index finger are taken into consideration one by one our experiment. While subject keeps the joint angle of the finger to which the moment of rotation is applied as initial condition, small external disturbance is given to the finger joint. From the time trajectories of the joint angle and the moment of rotation caused by the disturbance, impedance parameters of each joint are estimated. Inertia of finger joint depends on position from MP joint or root of finger, and MP joints of thumb and index finger have large viscosity and stiffiness. Especially, MP joint of thumb has very strong stiffness compared with all joints of index finger, and it plays an important roll for stable gripping motions. On the other hand, DIP joint of index finger has small viscosity and stiffness, which is appropriate to perform active probing motion based on touch sense of fingertips. Moreover, we investigate how initial moment of rotation has influence on impedance of the finger joints. It is shown that stiffness of each joint increases in proportion to the initial moment of rotation.

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The quality and the strength of human in-vivo bones are considered concerning the decrease of bone mass with aging and the health of bones. In this paper the strength is evaluated by indexes with respect to the Young's modulus and the flexural rigidity, which are derived from the product(fL)of natural frequencies(f)of ulna and the length(L). The natural frequencies were measured by impulse excitation and FFT technique. Total bone density and trabecular density were measured by the peripheral Quantitative CT(pQCT)method and then the cortical region was analyzed. These densities are compared with the strength indexes for 343 females of 20 to 88 years old. It is shown that the decrease of the strength indexes with aging is much larger than of total bone density being used for screening of osteoporosis.

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The purpose of this study was to investigate the ability of the human tactile sense to discriminate fine step-heights depending on surface motion. In the previous paper, we reported the development of a device which enabled to present a fine step-height ranging 0-30μm while moving at a velocity ranging 0-60 mm/s. This device was applied to investigate the human tactile sensation capability for moving fine step-heights. Six human subjects touched various step-heights moving at two velocities of 20 and 40 mm/s, and judged which step-height was higher. As a result of the psychophysical tests, the subjective equalities and the difference thresholds for discriminating the moving step-heights were determined. The experimental results proved that the difference thresholds and the subjective equalities resulting from a step-height velocity of 40 mm/s are larger than those from 20 mm/s. This reveals that the velocity of the step-height affects the discrimination capability, and that the resolution and the accuracy are decreased with the increasing velocity of the step-height.

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Communications and Broadcasting Engineering Test Satellite(COMETS)which was launched on February 21 in 1998 has a large movable antenna. This paper deals with a method to compensate disturbances caused by the antenna motion to the spacecraft attitude. The disturbances are calculated and compensated on-orbit based on the predicted antenna parameters. Then the parameters are estimated and modified from the results of the on-orbit compensation. The on-orbit experimental results show that the disturbance compensation is effective to reduce the spacecraft attitude error and becomes better by using the modified disturbance parameters.

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The vibration of first vertical bending mode of railway vehicle body greatly affects the riding comfort for passengers. In recent studies of authors, it is estimated that the arrangement of underfloor equipment with large mass and stiffness influences the dynamic characteristic of railway vehicle. Therefore, the purpose of this study is to optimize the arrangement of underfloor equipment to achieve the low vibration design of railway vehicle. The optimum design problem involves discrete design variables and a new response surface methodology, based on holographic neural network, is developed in this application. The sequential procedure and the stopping criteria are proposed. As the optimization result, the optimal position of the underfloor equipment makes the first bending frequency largest and it is confirmed that the first body bending vibration is reduced.

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In the design of railway truck, the axle supporting rigidity is one of the important matters for good running performance. Up to now, the axle supporting rigidity has been selected in the trade-off between running stability and curving performance. This paper deals with a design method for the axle supporting mechnism, which can manage both to secure the running stability and to improve the curving performance. This method utilizes the Bode diagram and makes it possible to evaluate the running performance in the frequency domain. The analytical model of a railway truck is represented as a feedback control system, in which the longitudinal rigidity of the axle supporting mechanism is regarded as the compensator gain. The gain corresponds to the supporting rigidity and it becomes high in the higher frequencies and low in the lower frequencies. An example of the axle supporting mechanism with such frequency characteristics is composed of three elements such as main spring, auxiliary spring and damper. The auxiliary spring and the damper are set in series and placed parallel to the main spring. The effects of the mechanism are shown in the numerical simulation considering track irregularity and the method is confirmed to be available to design the truck with steering ability.

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A machine that transports paper sheet by using a pair of flat belts, handles various paper sheet with regard to size, thickness and texture. This often causes the gap between the sheets to change when it is transported over a long distance. If the gap becomes shorter than a certain threshold value, it causes sheet jam. We have therefore developed a gap control system that determines the transport distance of sheets and measures the gap change before the sheets reach the gap controller. Using thses information, it estimates the gap change after the gap controller and sets a target value. The contoller varies the transport velocity in an optimum pattern and controls the gap to the target value. We applied the system to a transport route and it reduced the standard deviation of gap into 2/3.

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This paper proposes a method of improving the dynamic characteristics of infinitely stiff hydrostatic thrust bearing using a miniaturized self-controlled restrictor. This bearing has a very small self-controlled restrictor of 3.0 mm diameter and can obtain a very high static bearing stiffiness(nearly infinite stiffness). Influences of various design parameters on the dynamic characteristics of the proposed bearing are investigated, theoretically and experimentally. As a result, it was found that the miniaturization of a self-controlled restrictor can greatly improve the step response and the frequency response characteristics of this kind of hydrostatic thrust bearing.

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The vibrations of all-ceramic ball bearings having silicon nitride rings and balls were investigated and compared with those of hybrid ceramic ball bearings and conventional steel ball bearings. From the experimental results and discussion, the following results were obtained. (1)The overall vibratory velocity level of the all-ceramic ball bearing is influenced by the rotational velocities, and do not change with axial load. (2)The overall vibratory velocity level of the all-ceramic ball bearing is lower than that of the hybrid ceramic ball bearing and the conventional steel ball bearing. (3)The peaks of radial and axial vibration of the all-ceramic ball bearing appear in higher frequencies compared with the corresponding peaks of the hybrid ceramic ball bearing and the conventional steel ball bearing. The peaks are caused by the natural vibrations of the outer ring. (4)The vibration spectra of the all-ceramic ball bearing are mainly determined by the amplitude of the waviness of the raceways and ball suface, the Hertzian spring constant associated with the elastic contact between the raceways and balls, the normal elastic contact deflection between the raceway and ball, the number of balls, the contact angle, and the mobility.

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Surface modified rollers by electroless Ni-P alloy plating and sulfurizing were fatigue-tested under a pure rolling contact condition. The fatigue lives of both surface modified rollers were longer than that of the non-coated rollers and the fatigue strength of the sulfurized rollers was the highest. The influence of elastic modulus of a plated layer on the contact pressure and the subsurface stresses was examined with numerical analyses. The contact pressure and the subsurface stresses of a roller covered with a plated layer, whose elastic modulus was smaller than that of the substrate, were smaller than those of a non-coated roller, especially at the edge of the contact width. The conformity by the wear of the plated layer led to the reduction of the contact pressure and the subsurface stresses at the edge of the contact width. The reason why the fatigue strength of the surface modified rollers were greater than that of the non-coated rollers could be due to the smaller contact pressure and the smaller subsurface stresses.

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To clarify the friction and wear behavior of stainless steel SUS440C spur gears of which the surface layer was thermally diffused after being Sn-plated, a gear test was carried out under grease lubrication in air and in vacuum of about 1∼4×10^-4 Pa using a power-circulating gear test rig. From the tests, the following results were obtained. (1)The running time at the incipient stage of the destructive surface failure of the gears in air was about 1/2∼2/3 times as small as that in high vacuum. (2)The running time at the incipient stage of the destructive surface failure for the gears with a diffused layer was about 1/3∼1/2 times as small as that for the gears without a diffused layer. (3)For the gears with a diffused layer, a little effect of the molybdenum disulfide additive on running time to the destructive surface failure was recognized. (4)When the test could not be run due to a destructive surface failure of the meshing faces, either ratio of gear frictional loss torque to transmitted torque η or an acceleration due to vibration of the tested gear box α exceeded the value of η=0.03 and α=0.3×gm/s². It is possible to detect the degree of the destructive surface failure of the gears by means of the measurements of the frictional loss torque and the acceleration due to vibration of the gear box.

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Wear experiments were carried out on self-mated couples of Sn vs. Sn and Zn vs. Zn. An environmental controlled pin-on-disk test rig was used in which oxygen pressure can be varied from 10^-4Pa to 10⁵Pa. The coeficient of friction decreased when oxygen pressure was increased. This also resulted in an increase in the size of individual wear particles. The hardnesses of the transfer particle and rubbing pin and disk were measured after stopping the experiment. It showed that the transfer particle was approximately ten percent harder than the mating rubbing material. The high rate of wear in higher oxygen pressure, was attributed to the increase in the shear strength at the interface by oxide formation. According to the adhesion theory of wear, the amount of wear correlates positively with friction. On the other hand, our study shows that the change of shear strength at the interface is responsible for an increase in wear particle formation.

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The application of a low elastic modulus layer lining on the bearing surface of the joint prosthesis has been investigated to promote continuous film of lubricant between articulating surfaces by soft-elastohydrodynamic effect. However, these elastomeric bearing surfaces generally have poor tribological properties when a fluid film is not present. Thereforc the start-up frictional property is one of the major factors liniting the service life of the advanced prosthesis with compliant layer. The purpose of this research was to elucidate and characterize the start-up friction of segmented polyurethane surface against stainless steel. The smooth surface(Rrms=0.04∼0.05μm)of polyurethane plate gave a start-up friction which was significantly higher than rough one(Rrms=0.53-0.56μm). This seems to be ascribed to the difference in the preservation of lubricant and the adhesive action between two surfaces. The disposition of bearing surfaces, in which the polyurethane plate suffered continuous elastic deformation by counterface, made a start-up friction smaller, because the entraining of lubricant between surfaces was improved. In the condition where the adhesive action affected considerably on a start-up friction, higher hardness of polyurethane and smaller apparent contact area seemed to deduce the start-up friction.

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A numerical study of self-acting gas-lubricated wave journal bearings is presented for their dynamic performances : HFW(self-excited half-frequency whirl)stability and dynamic response of an out-of-balance rotor. The study is conducted under practical operating conditions by means of a nonlinear orbit approach. Numerical examples of wave bearings are compared with those of herringbone-grooved bearings, and it is found that wave bearings give relatively favorable dynamic performances. Considering both HFW stability and dynamic stiffness, three-wave bearings are recommended for a practical use. However, it should be pointed out that HFW stability of wave bearings is quite sensitive to the wave amplitude, and also the synchronous orbit geometry of an unbalanced rotor supported on a wave bearing can be complicated out of plain circle.

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Welding is widely used for construction of many structures. It is well known that residual stress exists nearby the bead because of locally given heat. Since tensile residual stress on the surface degrades fatigue strength, some methods for reduction of residual stress have been presented. In this paper, a new method is proposed in which vibrational load is applied during welding operation for reduction of residual stress without heat treatment. Advantage of this method is that vibrational load is generated by a small shaker. It is clarified experimentally that tensile residual stress near the bead can be reduced when this method is used. Experimental results are qualitatively explained by an analytical method. Using the analytical model with preloaded spring having elasto-plastic characteristic and considering change of dynamic characteristics during welding, reduction of residual stress can be evaluated. It is assumed that reduction of residual stress is caused by local plstic deformation because of low yield stress during solidification of welded metal. The proposed method is expected to be practical.

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In case of machining by the large-size machine tool, the vibration occurs easily as compared with machining by the medium and small-size one. This vibration deteriorates not only the quality of finished surface but also the sharpness of cutting edge, and furthermore the performance of machine tools. The impact damper needs some acceleration to effectively function and thus the low frequency vibration cannot be suppressed by the impact damper. In contrast, the dynamic damper needs some attached mass to effectively function, and thus it is generally difficult to apply to large-size machine tools. This paper describes the principle of a newly developed dynamic impact damper and simulated results of its motion in time domain. The paper also reveals that the dynamic inpact damper well facilitates the suppression of the low frequency vibration in large-size machine tools.

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Measurements of heat input generated in the plate cut by a laser cutting and a plasma cutting have been made for investigating a predictive equation. The heat input of cutting is called as the residual energy in the cutting field and is important factor for controlling the deformation generated through a thermal cutting process. The total energy needed for the thermal cutting was studied by many researchers and the predictive equation of the total energy was proposed by Wells. However the equation predicting the residual energy was not studied. The equation for the residual energy is derived from modifying Wells equation. By comparing the experimental data with the prdicted values, it is shown that the proposed equation is applicable to the evaluation of the residual energy.

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The purpose of this paper is to introduce a new approach for predicting chatter in high-speed end milling by using a fuzzy neural network. First, a milling experimental setup is built and a set of the valuable experimental data are acquired under different tool wear states and carefully selected cutting parameters. Second, the experimental system is simplified into a fuzzy neural network model which is trained in the experimental data. Third, some simulation results are obtained on the basis of the trained model. Finally, the calculated results are compared with the experimental ones in order to check the effectiveness of the method described.

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Considering from such a viewpoint as realizing the non-contact and driving-type painting or forced drying system of sphere, which has the advantage of leaving no mark on the sphere at the top of supporting pins, it is basically important to control the movement of sphere. A rotational motion recognition technique of sphere, which is considered to be essential for developing such a control system, is newly proposed in this paper. It consists of three modules ; a principle of detecting the axis and speed of rotation using Hall elements, a way of producing magnetic flux required onto the surface of sphere and evaluation of experimental results. Although having disturbance caused by the vibration and dimples of a golf ball chosen as the object, the proposed method is proved to be effective and valuable.

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This paper is experimental study of a pipe inside vibrating mover which is composed of a piezo-electric element. Mover travels inside a very small pipe having 11 millimeters and 4 millimeters diameter, and has a function of forward and backward movement by change of power supply frequency. The characteristic of movement is examined from results of experiments. The Poincare map is constructed by measurement of the vibration wave, and the property of vibration is studied. The principle of movement, which is obtained by the results of experiments and the measurement of the vibration wave, is examined.

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