In the present paper, the frictional oscillations in a mechanical driving system are studied theoretically on the self-excited and forced oscillations, when the friction-velocity characteristic curves are given as the combined curves of linear and hyperbolic functions and maximum static friction force is not an isolated point. Bodies acted upon by sinusoidal external force while sliding along a surface at a fixed velocity exhibit regular oscillations. We have analyzed these motions using an averaging method, without distinguishing between slipping and sticking. We have also examined the amplitude characteristic of motions found in the obtainable first approximations of the form of harmonic vibrations. Finally, we made a detailed investigation of the stability of these first approximations. Also, we have assembled the results of a comparison of the precise solutions for motions over a wide range of velocities where the kinetic velocity of the body exceeding the surface motion velocity, and we propose a usable theoretical analysis method, aimed at understanding the important aspects of regular harmonic solutions.

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Forced frictional oscillations in a self-excited system occurred when the maximum static friction force did not become an isolation point and the kinetic friction force was given as a combined function of the relative sliding velocity composed of linear and hyperbolic functions. This process of oscillation was reviewed by the averaging method in continuation of the previous report. The properties of the limit cycle occurring where there was only one unstable first approximation solution of the harmonic oscillation with the values of the oscillation force circular frequency and the moving surface velocity are explained in this report. Various characteristics of the resultant stable, non-harmonic oscillations are also reviewed. By comparing results of the previous report with highly accurate, piecewise linear approximation solution, it was determined that this averaging method workes quite well and therefore is an effective method for judging the stability of the solution. It was learned that the highly accurate solution of the sliding motion could be estimated quantitatively by the stable first approximation solution using the averaging method. The unstable region in the first approximation solution corresponded with the occurrence region of the non-harmonic oscillations in the highly accurate solution. The solution by the averaging method showed the qualitative change of the amplitude.

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Frictional oscillations occurring in a forced self-excited system were treated when the kinetic friction force was shown as a combined characteristic curve of linear and hyperbolic functions of the relative sliding velocity. The authors studied the characteristics and stabilities of the oscillations in the first approximate solution for harmonic oscillation form (among the steady-state oscillation solutions which can be obtained by the averaging method). The study results of various properties of the solution for non-harmonic oscillation solution accompanying the occurrence of limit cycles have been reported previously. Highly accurate, steady-state oscillation solutions (with consideration given to the two motions of slipping and sticking) are obtained with a computer by approximating the characteristic curve of the frictional force and slipping velocity with n broken lines and connecting the successive solution curves on the phase plane in the velocity boundaries of each broken line. The piecewise linear approximation method for obtaining a highly accurate solution which is very similar to the exact solution is explained first. The occurrence forms and the distribution conditions of various steady-state oscillation solutions unobtainable by the averaging method, including the maximum static friction force becoming an isolated point, are described. The resonance characteristics of the system and the effect of the velocity of the moving surface on the characteristics of the steady-state oscillation solutions are reported.

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This paper describes the experimental results of squeal of disk brake of floating type. The squeal of new type has a low frequency and a coupled vibration mode between rotor and caliper through pads. From the experiments, it was made clear that the occurrence of the squeal changes according to the contact distribution in the circumferential and the radial directions between rotor and pads. In the case of cutting a part of pad surfaces in the circumferential direction, it is effective for squeal reduction to cut the pointed end pad surfaces of leading side on the inner side, and in the case of cutting a part of pad surfaces in the radial direction, it is effective for squeal reduction to cut outer pad surfaces of inside in the radial direction. Moreover, frictional vibration of a block subjected to distributed friction at contact surface was treated analytically and experimentally and a common mechanism of vibration of block and disk brake was found.

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This paper presents an analytical model coupled between rotor and caliper through pads to analyze the low frequency squeal of floating type disk brake, and describes the analytical results, compared with the experimental ones shown in the previous report. From the analysis, it was made clear that the squeal changes according to the contact distribution in the circumferential and the radial directions between rotor and pads, that is, in the case of cutting a part of pad surfaces in the circumferential direction, it is effective for squeal reduction to cut the pointed end pad surfaces of leading side on the inner side, and in the case of cutting a part of pad surfaces in the radial direction, it is effective for squeal reduction to cut outer pad surfaces of inside in the radial direction. It was confirmed that these analytical results were in a fine agreement with the experimental ones.

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Identification of system parameters of structures is important for the damage detection or health monitoring of structures due to earthquake. Generally, the input and responses of structure is measured by the accelerometers during earthquake. Therefore, if it is possible to identify the system parameters by wavelet transform of input and acceleration response, it is very useful. In this paper, the method to identify the system parameters such as stiffness matrix and damping matrix by wavelet transform of input and acceleration records observed during earthquake is proposed. To verify the applicability of the proposed method, numerical simulations using the two-degree-of freedom system and the experimental using two story model are conducted. From both results, it is proven that the proposed method can give the good estimation for the system parameters compared with the other methods.

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We have already proposed the techniques to identify the parameters and to detect a small crack in the cantilever beam using the image processing. In this paper, we intend to improve an accuracy and to reduce the calculation time in our proposed techniques. By optimizing the location of nodes in the Spline smoothing, we could reduce the error in the image data and get more precise deflection data of the beam. The time consuming part in the damage detection program using the simulated annealing technique was the FEM calculation of the deflection of the beam. After introducing the nonlinear but exact model of the beam element into the calculation of the beam deflection, the significant reduction of the calculation time was achieved in this paper.

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Following the previous report, the skew of flat belt running between angular misaligned cylindrical rollers is investigated by experiments and FEM simulatiton. Both effects of parameters on the skew and the configuration of the belt between/on the rollers are clarified. The results show that the skew rate decreases with increase in the belt width or with decrease in the roller diameter and coefficient to friction. The skew can be considered to occur when the belt winding spirally around the roller moves together with the rotating roller.

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This paper proposes torsional vibrations of the clearance problem in coupling, joint and clutch for a rotating shaft system. To make researches into the vibrational phenomena of the system, bilinear spring stiffness models with hysteretic torque in clearance are developed. The dynamic behavior of this system is investigated by using a numerical simulation. It is demonstrated that the steady-state amplitude shows nonlinear characteristics and changes remarkably with the hysteretic torque of the system. The behavior of resonance curves is examined in detail when the equilibrium point of the torsional stiffness changes. The experiments are performed to confirm the results of numerical simulations, and the experimental results agree well qualitatively with those from the simulations.

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The unstable region of a circular cylindrical aluminium shell subjected to internal leakage flow was investigated experimentally, changing the gap shape and leakage flow velocity. The changes in the natural frequency, damping ratio, and displacement were also investigated to clarify the type of instability that occurred and to obtain the vibration characteristics needed for predicting instability. Flutter-type instability was observed and for an unstable gap condition, the damping ratio decreased to zero, as is known to occur with flutter-type instability. Moreover, the natural frequency increased with the flow velocity. The change in the natural frequency was small and the damping ratio increased with the leakage flow velocity when the gap shape was stable. The repeability of the flutter occurrence was good. Leakage flow through a straight gap did not cause instability, and the critical ratio of the size of the stepped annular gap for the unstable region was obtained.

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This paper deals with a theoretical stability analysis of flow-induced waves induced in a flexible sheet moving in a fluid-filled narrow space with shear fluid flow. In the stability analysis, wave equation of the system is derived from the equation of motion of the moving flexible sheet coupled with the shear fluid flow. The equation of motion of the moving flexible sheet is based on the Kirchhoff-Love's thin-plate model and the equations of motion of the shear fluid flow are based on Navier-Stokes equations. The dispersion relation of the waves are derived as a function of the moving speed of the sheet. As a result, the analytical results show that flow-induced waves occur in the moving flexible sheet due to the shear fluid flow when the moving speed becomes high, and clarify the phase speed (traveling-wave speed) and the growth rate of the flow-induced waves.

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This paper is concerned with the design of an active suspension system for one-wheel car models using fuzzy reasoning. The proposed active control for the suspension is derived as a linear combination of the defuzzificated values of the outputs in single input rule modules. The model is approximately described as a two-degrees nonlinear system subject to a random input. The experimental result shows that the proposed active suspension system more improves the vibration response of the vehicle body than a skyhook damper suspension system.

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The authors have been proposed self-powered active vibration control systems, which achieve active vibration control using regenerated vibration energy. They do not require external energy to produce control force. To realize the proposed system, the system must regenerate more energy than it consumes. It is important to estimate the balance between regenerated and consumed energy. This paper proposes the method to derive the energy balance from dynamical propertiy of systems, feedback gain of active controllers, specifications of actuators and power spectral density of disturbance. Then the condition under which the proposed system operates effectively is obtained. Experimental results validated our claims.

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This second report is studies on the methods of the controls of liquid surface wave in the case of an incline-type automatic pouring machine. The incline-type automatic pouring machine has two inputs, transfer for going to pouring place and rotation for pouring into the molds. The model is linear state equation model. When rotation and transfer generate waves, we made a one-mode model. First wave model parameters generated by rotations and transfers are identified by using frequency distribution data and the curve fitting approach, which is the least square mothod, by using the steepest gradient method. When rotation and transfer generate waves and the transfer pattern is previously known, a preview control method can be applied. The transfer pattern is fixed, so the transfer pattern can be used to reduce waves. The method is calculating the feed forward preview coefficients for rotation by using the optimal partial differential equation. Finally we demonstrated the usefulness of the approach presented in this paper through several control simulations and experiments.

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Vibrations of stay cables are often induced by wind because of their aerodynamic instability. They must be suppressed to prevent cable fatigue and to allay passenger fear. Although various countermeasures have been developed, totally effective one has not yet been established. The authors have proposed a new vibration reduction method called "Vibration modes changing method" using a permanent magnet. A magnet installed near the end of the cable changes the vibration modes passively by repeating motions of constraining and releasing cables. With this method, growth of the unstable fundamental vibration mode is prevented by dissipating energy of higher stable modes. Comparing with other methods, it is expected to improve low temperature characteristics, maintenance and manufacturing cost. Considering only unstable fundamental vibration modes, the vibration analyses were carried out taking account of gap effects. The results agree well with wind tunnel tests and the design conditions were obtained.

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For positioning control problems of vibration systems, a nonstationary optimal regulator (NOR) is known as one of the effective control methods. NOR corresponds to an LQ regulator based on a time-varying criterion function including time-varying weights. NOR enables us to produce positioning trajectories taking the vibration characteristic of a controlled object into account and omit another design of reference trajectories. In conventional studies on NOR, the time-varying weights were determined by iteration of numerical simulation. Different from these studies, this study shows NOR design using GA (Genetic Algorithm) meta-optimization for the determination of the time-varying weights. First, we discuss a useful combination of plural time-varying weights taking account of several control constraints. Secondly, these weights are optimized by using the GA approach. This method is applied to a single-degree-of-freedom vibration system positioned by a DC servo motor and a ball screw. The effectiveness of this method is verified by numerical calculations.

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This study considers active vibration control of a multi-story structure which consists of bar-connected masses repeated in the vertical direction with active mass drivers installed on the top. As an alternative to the vibration mode approach, the traveling wave approach is applied. To implement the impedance matching controller which is proposed for a damped mass-spring system, the loop shaping design procedure is used to consider the dynamics of the actuator and the sensor noise. The designed controller has similar properties of the impedance matching controller, that is, it is efficient for the disturbance at any position and the towers with any stories. Experimental results are shown to evaluate efficiency.

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The dynamic analysis of link structure, including both flexible and rigid bodies is developed in this study. The model of flexible body is based on FEM theory, and geometric nonlinearity effect is taken into account. The theory proposed in this study is improved about the problem of numerical integration error in the former theory. Moreover, in the flexible-rigid link structure, dependent variables are eliminated using the topological information. In general, Lagrange multiplier technique is used for the analysis of this system. In this method, the equation of the system is the form of DAE and it is not be able to be solved efficiently. On the other hand, the equation of the total system obtained in this study is the form of ODE and it is able to be solved efficiently

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This paper describes a new concept of deriving the analysis model for real-time simulation from the model of multibody systems, and presents suitable algorithm for real-time simulation. For real-time simulation, it is shown that the approximation of constraint equation and the transformation of coordinate in equations of motion are effective for reducing calculation. By numerical simulations of automobile, it is shown that the proposed realtime method achieves high-speed calculation with satisfactory accuracy.

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Traditionally, modeling of oil hydraulic devices depends too much upon classical 'hydraulics' and lacks in experimental verification. From a critical standpoint against this tradition, a measurement-based modeling was attempted for an oil hydraulic flow control valve. First the steady-state characteristics of the two essential components, that is, a throttle and a spool valve were thoroughly measured. With those experimental data, the new empirical equations expressing the static relationships between the differential pressure, the flow rate and the opening area were found out for both components. The static model including these relationships proved effective in predicting steady state behaviors of the flow control valve. The dynamic model was also formulated on the basis of the static model with kinetic inertial terms added. The experiments were carried out by transient-and frequency-response methods in which unsteady differential pressures, flow rates and spool displacements were all measured, proving the model's validity.

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Stress ratios have been used in inferring the maximum stresses of blades from the measured vibratory stresses. This method may not be applicable to the modern low aspect ratio blades because the patterns of high frequency tip modes (stripe modes) are drastically changed due to slight changes in structural properties. In this paper, the new method to predict the maximum resonant stresses of the stripe modes of low aspect ratio blades is proposed. The maximum resonant stresses of actual blades with geometric variations are predicted, using measured vibration modes of them, calculated vibration modes of the standard blade with the drawing geometry, and a few measured resonant stresses of blades with strain gauges. The validity of the method is verified from the numerical simulation. It is shown that the accuracy of the estimated maximum resonant stress is remarkably improved comparing to the conventional method.

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Recently the non-contact measurement methods using optical or magnetic probes have been applied for the measurement of vibration of rotating blades. The non-contact measurement methods of the rotating blades are classified into two categories by the form of data processing : multi-probe method and few-probe method. Though the multi-probe method can measure the amplitudes, frequencies, and circumferential modes, it is difficult to apply the multi-probe method to the measurement of the actual machine because many probes on the casing are required. On the other hand, the few-probe method is easy to apply to the measurement of the actual machine, but the few-probe method cannot detect the frequencies and circumferential modes. Consequently the few-probe method is not suitable to the detailed measurement. In this paper, the improved few-probe method, which has been developed to overcome the disadvantages of the conventional methods, is presented. In order to verify the validity of the proposed method, the numerical simulation and the measurement of the actual machines are carried out. From these results, it is confirmed that the improved few-probe method can detect the amplitudes, frequencies, and circumferential modes like the multi-probe method.

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Several studies have been performed on improving maneuverability and stability of articulated vehicles by trailer wheel steering, but no control system that compensates instability against the perturbations such as the tire force nonlinearity and maintains good performance on maneuverability as various vehicle velocity has been proposed. In this paper a new robust control system for trailer wheel steering system is presented. The purpose of this control system is to make the trailer follow the tractor exactly at any velocity. This system consists of a desired path generator and a trailer wheel steering controller derived from H^∞ model following control. Lastly, this control system is evaluated through a series of simulations based upon the nonlinear model in terms of off-tracking characteristics at low velocity and steering responses at high velocity. The results have indicated that this system is highly effective for reduction of off-tracking and directional stability.

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In order to realize higher positioning, we previously proposed motional mode decoupling control for a fine-motion stage. In this control scheme, both the motional mode selector and distributor are prepared. The former is the matrix to calculate the motional-mode signals from the sensor's outputs, and the later is the matrix to calculate the driving signals. However, the operation error of the motional mode selector introduces the positioning error. Then, in this paper, a modified motional mode decoupling control scheme is proposed to reject the above error. Firstly, this control scheme in which the motional mode selector is assigned on the forward-path in the feedback system is clarified. Next, the positioning performance of this scheme is illustrated by experimental results. Finally, the robust performance aganist the operation error is shown. Its feature is useful to reconstruct the motional mode decoupling control system instead of the conventional control system with individual feedback loop.

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A robust control like sliding mode control is suitable to AMB system with gyroscopic rotation because it is very difficult to obtain an exact mathematical model for AMB system. The aim of this paper is to realize a sliding mode control system based on fuzzy model for AMB system. A fuzzy model of AMB system is built from the input and output data of the actual turbo-molecular pump by using fuzzy neural network. The sliding mode controller is constructed for this fuzzy model of AMB system. We did the super high-speed operation test of the actual turbo-molecular pump by using that controller and obtained good results.

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An efficient FEM scheme for the transient response solution of a magnetic head slider is presented by using compressible Bolzmann-Reynolds equation. In this paper, after the finite element matrices are formulated by Galerkin method with respect to both space and time, the second order terms of smaller incremental change over the time interval are ignored. This yields a first order of integration that is compatible with the neglect of non-linear terms. Furthermore, when iterative solvers such as the conjugated gradient method are adopted to solve the FEM simultaneous equations, it is found to be very effective to shorten computational time. Finally, accuracy and computational time dependence on mesh and time increment are discussed in detail.

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This paper proposes an effective impedance control method for multi-link flexible robot manipulators. This method is based on an end-effector trajectory tracking control approach. First, the objective of impedance control is converted into tracking a targeted trajectory. The targeted trajectory is generated by a designed system possessed with the ideal dynamic characteristics in terms of moment of inertia, damping, and stiffness. Then, an ideal manifold is designed to prescribe the desired performance of the system in vibration damping and end-effector trajectory tracking. A control law is derived such that the motion of the system would converge and remain to the ideal manifold. Stability of the system is investigated using the Lyapunov theory. Simulations are carried out to illustrate the effectiveness of the proposed impedance control method.

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In this study, first, the hierarchical vehicle control system of a mobile robot moving along a wall is proposed. The hierarchical vehicle control system consists of a desired signal generator of wheel velocities using two laser displacement sensors and a wheel velocity controller. The wheel velocity controller consists of PI control and disturbance observer. Then, the numerical simulations and the experiments have been carried out, and the high-precision trajectory tracking control performance of the present hierarchical vehicle control system is confirmed.

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This paper describes a novel magnetic force control method using functional materials and its application in a magnetic levitation system. This force control is based on the inverse magnetostrictive effect of giant magnetostrictive material (GMM) and realized by composing a closed parallel magnetic circuit with a permanent magnet in magnetic yoke. The magnetic force between movable and fixed yokes can be adjusted by controlling the strain in the GMM rod. For the purpose of efficiently controlling the strain of the GMM rod, a magnet-electric composite element is constructed, in which two functional materials, a GMM rod and a piezoelectric ring actuator are mechnically coupled via strain. The magnetization in the GMM rod can be controlled by adjusting the voltage of the piezoelectric actuator. It is demonstrated that this element works to adjust magnetic force with low energy consumption and has high frequency bandwidth. As an application of this element. a magnetic levitation system was proposed. With simple PD control, the yoke was successfully levitated and the advantages of low power consumption was confirmed.

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A new transport module for constructing an efficient and flexible material handling system are proposed in this paper : an AGV (Automated Guided Vehicle) module loaded a conveyor in which it is possible to hand over a transported object between two modules. The operation can solve a deadlock problem among AGVs in the process of material handling. Prototype modules are created and hand-over experiments are made to measure three kinds of hand-over costs of the modules. Control strategy is proposed and transport simulations are made for a model plant layout by using the cost values in the former experiments. The results show the effectiveness of the proposed module and control strategy in comparison with singleloop and unidirectional type transportation.

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Large and highly variable deformations of the ACL cannot be adequately quantified by one-dimensional and/or localized measurements. Since the complex anatomy of the ACL makes uniform loading of all fiber bundles almost impossible, strains on specific portions being tested are considerably altered during knee movement. To observe the ACL's entire surface, we propose a photoelastic coating method. A simulator jig was used to allow a natural motion of the knee whose medial and lateral femoral bone parts were removed in order to expose the ACL for observation. The simulator jig with the knee was mounted on a universal stand which allows tilt and swivel rotations, so that the exposed ACL might be viewed from any direction. Measurements were performed on the strain distributions over the ACL at various knee angles. The panoramic images of the photoelastic fringe patterns yielded significant results.

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Static characteristics of the human finger are investigated using a planer musculoskeletal model of the finger. They are represented by mapping a muscle force vector to a manipulating force vector of the fingertip. Force manipulability of the fingertip is defined as a force manipulability set obtained from the mapping under the condition that the norm of the muscle force vector is not more than a unit value. The shapes of the sets are geometrically obtained and graphically represented in the simulation results. The simulation visually demonstrates the static characteristics of the finger.

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Response pattern of tactile receptors caused by the deformation of finger tissue when human perpendicularly push objects are needed to be clarified in order to understand the mechanism of tactile perception of softness. In the present study, deformation of the finger tissues when a finger is in contact with an object directly, through pin matrix and/or rubber sheet is calculated using finite element (FE) analysis. Tendency of perception of softness when finger touches an object is also examined using a psychophysical test. Relationship between the deformation of finger tissues, elasticity of the object, and the perception of softness is clarified by comparing results of the FE analysis and the psychophysical test. It is also shown that the rubber sheet on the pin matrix is important to present softness of the object.

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This paper presents a study of the relationship between the contraction on the sole surface, the shape and the forces generated by muscle for locomotion of snail (Gastropod). We observed sole surface of a moving snail to investigate the state of contraction when a sole wave is passing. Then we measured the vertical and horizontal forces generated by sole to investigate the relationship between the forces and the shape of sole surface. Based on these results observed, we proposed a model of the shape of snail's sole section. The mechanism of snail's locomotion will have a possibility to be applied to the mobility equipment which has flexibility for ground conditions and can easily turn in a house.

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This paper describes characteristics of impact force in human placing motion. The experimental result says that the human performs placing motion dexterously without violent impact force due to keeping the upper frictional forces of the fingertips, which is applied on the grasped object after the object contacts with the floor. Slow change rate of moving the object mass to the floor has the effect of reducing the peaks value and temporary convergent value of the impact force. Moreover, smaller grasping force at a moment of collision can restrain the violent impact. Next, taking the strain pattern of the fingertips into consideration, the simulation of human placing motion is performed. When the viscosity of the fingertips in the shearing direction is higher, the impact force of the simulation has high convergent value similar to the case where the grasping force is set to be larger.

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This paper proposes a method to generate human like arm movement to catching a moving object. Firstly, human arm movement is analyzed to catch a constant velocity's object and discuss several typical characteristics. Then a time-varying LQG controller is designed to take account human characteristics into robot motion. This controller holds the values of non-linear terms in the dynamic model of robot arm during one sampling interval, which are updated at each sampling step. Adopting this criteria, we can get an optimal control input easily in real-time, and modify the controller with arranging the weight matrices in LQG criterion. Using these time-varying weight matrices, arm movement is generated considering with the characteristics of human behavior. Finally, the valodity of this method is confirmed with some simulation results.

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Relative motions of balls, the inner race and the cage to the outer race of the Rzeppa constant velocity joint deviate from their ideal motions due to clearances between pairing elements. In this paper, output angle errors, eccentric motions of the inner race relative to the outer race and three dimensional deviations of the cage relative to the homokinetic plane with several joint angles are experimentally analyzed. The closed loop equations such that three balls may contact simultaneously their inner and outer races with one point or two points and the constraint equation for three balls so as to move in a plane by the cage are solved strictly for prescribed positions of the cage relative to the outer race. The obtained kinematic model of the Rzeppa joint simulates error characteristics of the relationship between input and output angles, which are about sinusoidal with period of 2π or 2π/3 according to the value of joint angle. Consequently, contact positions of three balls and their grooves and relative motions of elements are made clear.

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Nongrashof planar four-link mechanisms, that none of two neighboring links can make a complete rotation, generate complex coupler curves with highly nonuniform velocity when the driving link oscillates in such a manner that coupler and driven links belong to different composition loops in going and returning respectively. In this paper, for the purpose of classification and synthesis of nongrashof mechanisms, a procedure is presented for arranging points on the coupler curve with an equal distance, in which the input and output angles are interchanged according to whether the differential coefficient of the output angle is greater than some reference values or not. Furthermore, a pattern matching method is presented for synthesizing the coupler curve of the nongrashof mechanism. The method consists of magnification or reduction of the coupler curves, arrangement of equidistant points on desired and coupler curves, such a correspondence of points on both curves that the norm of the sampled values of their natural equations may be minimized and coordinate transformation of the coupler curve so that the maximum difference between both curves may be minimized.

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A differential motion restraint coupling is presented. In order to have strong torque, multi friction plates are installed in the friction unit of the device that involves magnetorheological fluid. Two permanent magnets lie on both sides of the friction unit. Hence, electromagnetic forces freeze the magnetorheological fluid. The friction plates have a number of slits in the radial direction, which generate torque due to shear forces between the frozen fluid and the slits. A design method has been presented for the device. To validate the present design formulae, experimental tests have been carried out. Calculated results are in good agreement with the experimental ones.

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This paper presents a study on effects of gear-side case-hardening on residual stresses of case-hardened gears. The carbon content of each element of the FEM models due to carburizing was computed on the basis of the relation between carburizing condition and carbon content distribution. A heat conduction analysis and an elastic-plastic stress analysis during the case-hardening process of spur gears were carried out for various case-hardening conditions by the three-dimensional finite-element method (3D-FEM), considering changes of the thermal expansion coefficient and the yield stress with the temperature and the carbon content distribution, and then residual stresses were obtained. The effects of the case depth, the case-hardened part (tooth surface, gear-side and bore), the face width, the rim thickness and the standard pressure angle on the residual stress were determined.

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This paper dealt with an inspection method of gear noise at non-integer components of meshing frequency. First, it was confirmed that this noise was generated by tooth surface error formed by the vibration of shaving machine tools in shaving process. Second, we proposed the introduction of FFT processor in a gear checker system in order to measure the periodic component of tooth surface error. The gear with this tooth surface error was estimated by this system. On the other hand, the meshing transmission error (MTE) and the vibration on the gear housing were measured. From comparing these results, it is shown that the proposed measuring system is effective to estimate the gear noise at non-integer components of meshing frequency.

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In order to evaluate the surface durability of ion-nitrided sintered powder metal rollers, the influence of particle diameter on the surface durabilities of the sintered rollers was investigated under a sliding-rolling contact condition. The failure mode of the rollers was spalling due to subsurface cracks. The surface durability of the roller became higher as the particle diameter became smaller. The spalling failure depth agreed almost with the depth where the amplitude A(τ_yz/Hν) of the ratio of orthogonal shear stress to Vickers hardness became peak. The surface durability was evaluated using the amplitude A(τ_yz) of the shear stress and the hardness Hν at the peak amplitude of A(τ_yz/Hν). The relationship between A(τ_yz) and Hν of the sintered rollers and gears having medium pore distribution was given by an equation A(τ_yz)=0.174Hν^1.13. However, the relationship of the sintered rollers and gears having different pore distribution did not conform to the above equation. Therefore, it could be said that the surface durability of the sintered roller depended on the pore distribution.

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This paper presents a study on the surface durability of ion-nitrided rollers. The durability of S45C ion-nitrided rollers with different case depths was investigated by carrying out running tests. The results were compared with the results for normalized and tufftrided rollers. The contact fatigue strength of ion-nitrided and tufftrided rollers tend to increase with an increase of case depth. The contact fatigue strength of the ion-nitrided roller was found to be much larger than that of the normalized roller and to become larger than that of the tufftrided roller with an increase of case depth. The surface failure mode in this experiment for ion-nitrided and normalized rollers was pitting due to the surface cracking but that of tufftrided rollers was spalling due to the subsurface cracking.

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A precise analysis has been made for a design method in order to obtain the profile of a pencil type relief grinding wheel for a hob which cuts a given screw rotor surface, especially in the case in which the cutting edge profile of the hob is given as a series of dispersive points. Firstly, it is clarified that under certain circumstances a singular point (a cusp) will occur on the profile of the relief grinding wheel corresponding to the cutting edge profile of the hob, and that, because of the cusp, the interference phenomenon will occur on the profile of the relief grinding wheel. Secondly, numerical analyses for the following two purposes arc proposed. One is to determine the interference by using a conditional equation of the cusps. And the other, which is more important is to obtain the profile of the relief grinding wheel. Then, these theoretical analyses are verified by applying them to the dimensions of screw rotor hobs.

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Tribological characteristics of hydrostatic spherical bearings used in hydraulic piston pumps and motors are studied theoretically and experimentally in mixed and fluid film lubrication. The basic equations considering metallic contact are derived using the mixed lubrication model which is based on the asperity-contacting model and the mean flow model. The effects of surface roughness, supply pressure, load, rotational speed and the seat geometry on the eccentric ratio, fluid pressure distributions, asperity-contacting pressure, leakage flow rate and the power loss are examined. The theoretical results are compared with the experimental data and the good agreement is shown.

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The influences of the used oil on the piston ring friction were evaluated by using a pin-on-disk type reciprocative sliding test equipment and an actual operating diesel engine in which the floating liner method was adopted. The major results are : (1) Because the used oil which contains highly concentrated soot is inferior in oil film spreading characteristics, the lubricating property is significantly lowered by reducing the oil supply rate ; (2) Even though the kinematic viscosity of the used oil is increased by the flocculation of soot, the effective viscosity on the sliding surface of the used oil is approximately equal to that of the fresh oil due to the de-flocculation of soot. The friction mean effective pressure obtained for the used oil is not different from that for the fresh oil ; and (3) Because the oil starved lubrication is dominant for the piston ring pack, the used oil raises the lubrication severity at the beginning of the power stroke, thereby causing the boundary friction to increase.

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A dynamics study of herringbone-grooved gas journal bearings is presented placing emphasis on a comparison between infinite and finite groove number solutions. The study is conducted under practical operating conditions by means of a nonlinear orbit approach. The analysis scope includes a grooved member rotating system as well as that with a smooth member rotating. Numerical examples show that the infinite groove number assumption predicts the self-excited half-frequency whirl stability with tolerable accuracy unless the rotor is fully grooved. Also, it is found that the assumption gives a fair approximation to the synchronous orbit amplitude evaluated by the exact finite groove number analysis. However, it should be noticed that the infinite groove number theory tends to overestimate both the stability performance and the synchronous vibration stiffness.

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In order to clarify the formation mechanism of surface roughness of steel sheets in cold rolling, the cold rolling experiments are made using carbon steel (SPCC) and stainless steel (SUS430) sheets with various surface roughness at the entry of rolling, and in neat lubrication of two mineral oils with different viscosities. Also, the shifting coefficient of weighted average roughness, which is called m-value, in a surface roughness equation is calculated by applying the rolling experiment data to the surface roughness equation proposed in this paper. Then, the formation mechanism of surface roughness of cold rolled steel sheets is discussed. As a result, it has been found that the m-value is larger than 1 and increases with increase of the initial equivalent surface roughness.

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In order to clarify the mechanism of lubrication in boundary lubrication areas in cold rolling of steel sheets, the cold rolling experiments are made using stainless steel (SUS 430) sheets with various surface roughness at the entry of rolling, and in neat lubrication of two mineral oils with different viscosities. Also, the friction coefficient in boundary lubrication areas and the thickness of lubrication film due to mechanical capture are calculated with the numerical analysis model of cold rolling lubrication and the rolling experiment data. Then, the factors affecting them and their characteristics based on the factors are discussed. As a result, it has been found that the friction coefficient in boundary lubrication areas is affected by the pressure ratio p_m/(σ_y0α_y0) and that the thickness of lubrication film due to mechanical capture is influenced by the initial equivalent surface roughness.

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In this work, a feasibility study has been conducted to determine if GHTA (Gas Hollow Tungsten Arc) method can be used for the welding in space. As previously described, the test for GHTA welding of stainless steel without filler wire has been successfully performed in a simulated space environment, produced by the parabolic flight of aircraft. In this paper, melt-run welding tests and butt welding tests on stainless steels for GHTA welding with filler wire have been conducted in a vacuum chamber using a developed compact wire feeder. The results are summarized as follows. (1) The developed compact wire feeder makes it possible to add the filler metal to GHTA weld pool smoothly in a vacuum. (2) A metal vapor plume is formed on the molten pool in GHTA welding and it grows brightly with increase of arc current. (3) The penetration depth in GHTA welding becomes shallow with increase of filler metal, as well as that in GTA welding under the atmospheric pressure. (4) The butt joint welded by the GHTA method of filler wire addition has no defect and it has enough strength.

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