An optimization method is presented to maximize the lowest frequencies of laminated composite shallow shells of rectangular planform. An exact solution is obtained to the governing equations of motion by assuming a symmetric laminate and simple supports along four edges After introducing each fiber angle as a design variable, a set of equations is derived to satisfy, the Kuhn-Tucker condition, and an optimal solution is obtained for given shell configurations. In numerical examples, effects of shell curvatures upon the optimal solutions are discussed.

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We propose an antiresonance-enforced active vibration absorber system, in which the passive dynamic vibration absorber is weakly damped and tuned to the peak frequency of the vibration of the main mass, and then, the active control system of the optimum design with a freqtuency-shaped cost functional is added to enforce the antiresonance. This system is a variation of the hybrid vibration absorber but is more effective than the conventional one, especially when the external excitation force is a harmonic wave or has a sharp peak in the spectrum. With the cross-correlation function, the system can automatically tune the antiresonant frequency to the peak frequency, and reduce the vibration effectively even when the peak frequency of the external excitation force changes In the paper, the theoretical analysis of the system, the digital realization and control stability are discussed, Finally, the experimental results, which show the effectiveness of the mechanism, are given.

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In this study, genetic algorithms (GAs) are utilized as a framework for Monte Carlo optimizations of the passive gyroscopic damper (PGD). The PGD is an effective damping mechanism for rotational vibrations, however, it shows considerable nonlinearity under strong excitations. The response to the random excitations can not be precisely analyzed by any conventional approximate method. The Monte Carlo approach exploits numerical simulations using pseudorandom numbers as the excitations and a numerical integration algorithm. The Monte Carlo estimations of the station ary response to white noise excitations are combined with the GAs. The quasi-continuous generation model with an algebraic crossover is customized for noisy Monte Carlo estimations, and it realizes a stochastic hillclimber. The gimbal spring constant and the giambal damper coefficient are optimized to minimize the stationary variance of the main system angle, as in the previous study of the same authors, wherein the Fokker-Planck method was employed together with a nonlinear programming algorithm. The GA solutions are again verified by the Monte Carlo estimations to prove their superiority to the previous ones.

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By controlling spring stiffness, vibration reduction and isolation of a multi-degree-of-freedom mass-spring system are achieved in this study. The control algorithm of the spring stiffness is based on the variable structure systems (VSS) theory, The stiffness-controllable spring is achieved by using two straight bars that are hinged to the mass along a line perpendiculal to the direction of mass motion and an axial force is applied to these bars. Since the axial force causes a restoring force which is equivalent to that of the spring. the stiffness is controlled by the axial force. In numerical simulations and experiments, the settling time of the impulse response and the displacement transmissiblility are investigated. The results show that the proposed method is effective in suppressing shock motion and in isolating vibration transmitted from the floor.

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The performance of the seesaw active mass damper (SAMD) is considered in this paper. SAMD is constructed such that the support frame of a tuned mass damper is driven like a seesaw by an actuator. In the numerical calculations, transient and seismic responses are compared between the types of SAMD and the tuned mass damper (TMD) by using a single-degree-of-freedom model. Furthermore, in order to examine the feasibility of SAMD, a SAMD was fabricated using the drive mechanism of a ball screw and a DC servomotor, and the control experiment was carried out. As a result, SAMD showed good vibration control performance. Furthermore, the experimental results are in good agreement with the result of numerical calculation.

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Many industrial robot manipulators have a cantilever structure at the base end of which the driving motors are located. Flexibility also exists at the transmission part between the motor and the corresponding arm. In terms of control, such structure has less rigidity so that residual vibration arises at the end point of the manipulator when it is brought to a sudden stop during operation. Our aim is to design a robust controller via μ-synthesis, which eliminates the vibration, or suppresses it to an acceptable level, at the end point of the third arm of a SCARA-type robot using available information of the motor angles of the first and the second arms. The effectiveness of the derived controller is examined through simulations and experiments in comparison with a PD controller. The experimental results show that the controller can significantly suppress the residual vibration with an excellent robust performance against the uncertainty of the robot parameters, while the PD controller gives poor performance in such a case.

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In servo-controlled machine systems, such as robotics or industrial machines, several kinds of gear reducers are proposed and employed selectively. Usually, these gear reducers caused speed and torque variations depending upon their element error, alignment error, etc. Such variations excite driven machine systems and cause vibrations. This paper deals with the technique of eliminating such variations locally generated inside the gear reducer in a lower-frequency domain. To eliminate these low-frequency components of variation, a local feedback loop control scheme is proposed to establish a self-compensating function in geared systems. Consequently this control scheme suppresses the vibrations in the driven machine systems. Experiment using a harmonic drive gear reducer show satisfactory control results.

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This paper presents a method of vibration suppression of a rotary compressor for a room air conditioner by using a torque control. First, the dynamic characteristics of a compressor driven by an induction motor are confirmed using analytical simulation and experimental data. Second, the feedforward control of input voltage for an induction motor which increases motor output torque in the range of the required angular position of a load torque is applied The analytical study indicates that the reduction of compressor vibration is possible in a low frequency range.

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This report deals with the experimental and analytical study of seismic response behavior of piping systems in industrial facilities such as petro chemical, oil refinery and nuclear power plants. Special attention is focussed on the nonlinear dynamic responses of piping systems due to frictional and collisional interaction among piping and supporting devices. A spatial mock-up piping and supporting structure model wherein piping is of 30 m length and 216.3 mm diameter is excited by a large-scale (15m×15m) shaking table. Frequency response function and the loading-response relationship in the form of a hysteresis loop under several excitation levels are obtained. The energy dissipated by friction and collision is evaluated, and the response reduction effect due to friction and collision is quantized and evaluated in terms of "response reduction factor" and linearized damping ratio. Numerical analysis using a FEM model is also performed. Calculated of maximum displacement responses of piping are compared with those from the vibration test.

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A drive mechanism using swing motion is proposed. A body is supported by three wheels, two of which are fixed to the body. A rod is pinned to the body and can swing like a pendulum about the pinned joint The third wheel is located at one end of the rod. Applying swing motion to the rod makes the body move forward. Analysis is performed for a physical model. Good agreement between experiment and analysis is obtained when the frictional force between wheels and floor is considered. Effects of swing velocity and geometrical parameters of the body on motion are clarified experimentally and analytically. The thrust force is due to the centrifugal force of the body during swinging.

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Active suspensions have been studied to improve the ride quality of railway vehicles. In many cases, pneumatic actuators were employed in those studies. This paper deals with the application of oil-hydraulic actuators, which are expected to have stronger control effect on the running vibration. This is examined experimentally by using an actual-size vehicle model on a test stand. The LQG control law, in which state variables are estimated from measurable accelerations on actual railway vehicles, is adopted. The LQ control law, in which state variables are measured accelerations and their integrated quantities, is also adopted. The results show that both controllers have good vibration isolation performance in both harmonic and random excitations. The control force and the stability are improved by decreasing the lateral damping in parallel with the actuator in the secondary suspension. In this case, it is confirmed that the relative displacement between the car body and bogie does not increase.

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This study forms the first step in developing a new tire model to use in analyses of vehicle handling. The structure of a complete tire model describing static and dynamic tire behavior is proposed. In this paper, two parts of the complete tire model are described, one for steady-state behavior of side force and self-aligning torque, and the other for transient-state behavior of tires. The model is an empirical one and is constructed using neural networks. It is shown that the output of the model describes the actual tire characteristics not only qualitatively but also quantitatively.

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A numerical approach has been proposed for estimating the coupled motion of a skier and skis when the skier performs "up-weighting" motion or "down-unweighting'' motion on the skis resting on a horizontal snow surface. The skier is modeled by a particle. The ski is assumed to be a nonhomogeneous beam. The bending deformation of the ski is taken into consideration, but the twisting deformation is neglected. Since it is very difficult to measure the coupled motion on snow, the experiment was carried out using a thick urethane sheet instead of snow. The measured force displacement relationship was used in the calculation. "Up-weighting" motion and "down-unweight-ing" motion were performed on the skis resting on the urethane sheet spread on a force plate. The motion was videotaped. Using the image, the displacement of the skier's center of gravity was measured by the image processing technique, Using the relative displacement of the skier's center of gravity from the shoe center, numerical calculations were carried out. From the comparison between numerical and experimental results. it has been concluded that one can accurately estimate the coupled motion by a numerical approach.

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This paper is concerned with a dynamic simulation method for a highly viscous fluid mount, which has recently been used for vibration isolation. However, the characteristics of the highly viscous fluid mount depend on frequency and displacement, and it is difficult to model the mount using a previously studied method. In order to create an equivalent mathematical model which considers the frequency and displacement dependency of the mount, the adaptability of a nonlinear three-element model is studied. It is confirmed that the nonlinear three-element model is appropriate for modeling of the highly viscous fluid mount by comparing the analytical results with the experimental results.

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This paper is a preliminary study of the dynamic torque in a rotating shaft of servo mechanism using a magnetic lattice. The magnitude of the torque is proportional to the angular twist of the shaft, which is obtained as the relative angular displacement of two positions at some distance apart on the shaft. This displacement can be detected as the phase differences between two magnetic sinusoidal signals on magnetic tapes. However, it is difficult to detect the dynamic torque accurately, as the measurement data contain noise and the system parameters always fluctuate. Using data concerned with phase differences including color noise, this study aims to estimate the actual value of the torque by the application of an H-infinity control theory. With special consideration given to parameter variation, the robust estimator is designed and its effectiveness is verified through simulation studies.

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This paper is a study on the development a soft handling two-fingered miniature gripper driven by a piezoceramic stack. The system is essensially a magnifying mechanism cut out of a monolith. It is composed of a piezoelectric actuator, a flecxible-hinged two-stage linkage and a force sensor attached at the tip of one of the fingers. A linkage that effectively transforms longitudinal expansion/contraction of the actuator into lateral fingertip motion is designed. Furthermore, a highly efficient compact force sensor is developed for measuring a minute force at the fingertip. The mathematical model of the electromechanical system is developed and applied to the study of a PID control problem where the gripper holds the object with a time-constant force 0.036 N.

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A new type of acoustic emission (AE) sensor was developed for detecting head-disk interaction in magnetic disk devices. In order to develop a small sensor, we used a thin-film piezoelectric material and mounted it on the Si slider using micromachining techniques. We conducted a basic experiment and a simulation of sensor output, and confirmed that the simulation used here can predict sensor output characteristics, This paper describes the structure of the sensor and the method of simulation. We also performed several other simulations of sensor output characteristics using this method, and confirmed that the new sensor is applicable to tribological research on head-disk interaction.

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We implemented the classification procedure using the multilayer perceptron (MLP) on the leak localization problems of fluid pipe networks. In our implementation, we first segmented the whole pipe network into a finite number of regions or pipe groups. Then we trained the MLP to produce the relationship between the measurement values and the leak region. Because an MLP for 1 out of M classification problems approximates the Bayesian posterior probability, we can estimate the leak probability for each region. Using this probability value we updated the segmentation to improve the resolution around the leak position. We also considered the allocation of measurement points, and implemented a genetic algorithm procedure to improve it. Numerical simulation results are presented to show the validity of these algorithms.

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There are positional and geometric uncertainties in assembly operation. In order to perform an assembly operation by robot successfully, it is necessary to estimate the correct position and geometric information of a fixed environment. This paper describes a technique that can estimate the contact position and geometric information between the object and the environment from a number of positions and orientations of a moving object, which are measured while the object is dexterously slid and rotated on the environment around the contact position. It is assumed that the environment and object are polyhedra. There are three kinds of basic contact pairs when the two polyhedra are in contact with each other. Corresponding to these basic contact pairs, three kinds of estimation approaches are proposed. By these estimation approaches, the environment position and geometric information on contacting parts can be estimated successfully. Experimental verification on the proposed approaches is performed and its results are outlined.

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The most popular fuel level measuring method presently in use employs a float and a resistor plate. This float follws the fluctuations of the fuel surface in an automobile fuel tank. A new accurate measurement of the variation of the cavity volume in the fuel tank has been investigated. This sensor is composed of a speaker, microphone and three Helmholtz resonators. This method detects the level and slant angle of the fuel surface. The sound frequency obtained experimentally is compared with the calculation result of the frequency found by the theoretical analysis in which the cavity system is connected with three Helmholtz resonators. This method of measuring the volume is applicable to measuring the fluctuating fuel surface in an automobile fuel tank.

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Information processing equipment such as a copy machine, which contains motors, generates vibration and noise varying as a function of time, frequency and space in a cycle. This mechanism cannot be analyzed by conventional spectrum analysis using time and space averages, because a transient state occurs. In this research, by applying short time principal component analysis, the number of independent vibration and noise sources is extracted from the signals of acceleration pickups and microphones. These results show the change of vibration and noise sources, including external noise, in a cycle. Vibration and sound pressure patterns can be expressed continuously, based on measurement or prediction by the boundary element method using vibration data on the surface of the structure in each instance. Moreover, transient external noise can be separated from vibrationally induced noise in practice.

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A new method of using a high Tc superconductor as two functions of levitation device and velocity sensor is introduced. The levitated object is controlled with an electromagnet using the measured velocity signal, that is, the system involves a hybrid magnetic levitation of superconductor pinning effect and active magnetic bearing. The experimental setup of a single degree-of-freedom system is made using a cantilever beam. A coil is wound around a permanent magnet which is used as a velocity sensor, This coil produces electromotive voltage in proportion to relative velocity. In order to insulate against vibration from the base and to reduce vibration from external force an H_∞ optimum controller is designed. A simple experimental setup is made and the results obtained are discussed in detail.

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This paper deals with the discrete time sliding mode control of a rotor-magnetic bearing system with a zero power scheme using a permanent magnet. We propose a new actuator in which the flux circuit of the zero power scheme using a permanent magnet can be varied. A mathematical model of the zero power scheme using permanent magnet and a flexible rotor is derived. The reduced-order model is described for the controller by eliminating higher-order modes of the mechanical and electrical magnetic interaction system beyond the fourth flexible mode, The sliding mode control system for this reduced-order model is designed using the discrete time VSS observer. The simulations are done for the two cases of life off and rotations The two unstable rigid modes can be easily controlled with good stability, and the spillover phenomena of the higher-order modes are not generated. It is also clear that the proposed discrete time sliding mode controller has robustness against model parameter variations and external disturbances, compared with the conventional control methods like PID control and disturbance cancellation control.

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This paper is concerned with motion control of an experimental electric vehicle. A research and development project has been undertaken to make an experimental electric vehicle with four independently driven and steered wheels. The vehicle has advanced dynamic control capability, optimizing the inherent advantages of the electric vehicle which is powered by electric motors. In order to obtain improved vehicle handling performance in a 4WS-4WD mode, which is a major feature of the vehicle, the rear-wheel steering system and the traction force differentials between right and left wheels are adopted as the control methods. The effectiveness of the proposed controls is shown by computer simulation.

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In this paper, we discuss the position control of a two-link arm. The first joint is a free one and the second joint is an active one. The system in this case is uncontrollable locally; thus we investigate the motion characteristics of the system globally. As a result, we find that the system can be controlled without using any additional equipment when the system has friction at the free joint. Two control algorithms using the friction torque at the free joint are presented with numerical examples. One algorithm controls the joints separately and the other controls the joints simultaneously.

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Robotics and automation in space development, such as construction of space structures or servicing of satellites, will be needed in order to reduce the workload of astronauts, and increase the operational efficiency and safety of space missions. In this paper, making use of the sliding mode control method, a design for the robust control system of a space manipulator is presented. A model of the space manipulator which has an end effector for capture of a target floating in space is considered. The effectiveness of the proposed method is demonstrated by the computer simulations and the experiments using a two-dimensional experimental facility which simulates a two-link space manipulator system. Its relative merit is assessed through comparison with other methods.

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Manipulating an object is one of the most important tasks of robots. Numerous studies have been carried out on object manipulation algorithms and optimizing control force. When robots try to manipulate an object on some environments, in other words, when robots try to draw an object, they must take the effect of friction into account in order to control the object smoothly. In this paper, a friction compensation method is proposed for control of drawing an object using a specialized neuron which is connected to a fuzzy neural network. The specialized neuron learns the friction effect only when the object dose not move against applied force. The fuzzy neural network is used for object trajectory control. The controller consists of a main fuzzy neural network controller which includes a neuron for friction compensation for object trajectory control and sub-fuzzy neural network controllers for manipulator force control to the object. Furthermore, modified Delta-Bar-Delta learning rate adaptation method is introduced for the main neural network controller. Computer simulation was performed to evaluate these proposed methods.

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A stochastic fuzzy control is proposed by applying the stochastic control theory, instead of using conventional fuzzy reasoning. We first solve a control problem of one-step predicted output tracking for linear stochastic systems. We then derive a dynamic multiple model adaptive control (MMAC) for the initial data distribution, given the uncertainties of the initial states. We further consider a static MMAC that can be applied to the case of completely unknown plants. It is shown that a stochastic fuzzy control has some Gaussian potential functions as membership functions and can assign some a priori probabilities to the fuzzy sets or to the control rules, if the probability density function with respect to the output error is replaced by a simple characteristic function. It is also clarified that the stochastic fuzzy control becomes a conventional fuzzy control by assuming that all of the a priori probabilities are equal at any control instant.

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The role of the a priori probabilities is unclear for a stochastic fuzzy control with a single vector data described In the first report, because in such a case the number of Gaussian potential functions is equal to the number of Control rules. In addition, as in a conventional fuzzy control based on fuzzy reasoning, it is necessary to clarify the relationships between the fuzzy sets and the control rules. We here consider a static multiple model adaptive control (MMAC) for the initial data distribution, in which it is assumed that a single vector data is partitioned into two subvector data and the hierarchical hypotheses are introduced with respect to each initial data distribution. Then, two kinds of stochastic fuzzy Control are proposed on the basis of such a static MMAC: one Case assigns the a priori probabilities to the fuzzy sest for each subvector data, and the other case assigns the a priori probabilities to the control rules.

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A stochastic fuzzy control is applied for the trajectory tracking control of a mobile robot with two independent driving wheels. In this approach, the fuzzy control system can be realized as a stochastic control. That is, the control system mainly consists of two parts: one is an estimation part which estimates the initial state by using a static fuzzy observer; while the other is a feedback control part consisting of a constant feedback gain and the estimated initial state. When the control object is assumed to be unknown, the control gain can be designed from the viewpoint of a variable structure system (VSS) control theory. On the other hand, when the control object is assumed to be known, the control gain can be easily designed from the viewpoint of a pole assignment. It is also pointed out that uncontrollable state mode data are not necessary for constructing the stochastic fuzzy controllers. The effectiveness of the proposed method is illustrated using computer simulations.

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Cone coupling is one of the fixing mechanical elements between a boss and a shaft. It has been extensively applied to the transmitting system of torque which has many fluctuations such as diesel engines, instead of the well-known key coupling. The objective of the present investigation is to clarify the mechanism of demounting the boss from the shaft when repair is required. The conventionally adopted method of demounting the boss from the shaft is to pour oil into the contacting surface through an oil groove which is premachined on the contacting surface of cone coupling. Normal contacting stress distributions were calculated by a finite element method (FEM) for symmetrical elastostatic contact problems. Demounting experiments were performed employing an S45C boss and shaft and Morse taper No. As a result, it was found that the demounting pressures could be achieved by assuming an equilibrium between the frictional force acting on the contacting surface and the thrust force. We obtained fundamental data about demounting for the cone coupling.

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The staircase method is of the statistical method used in fatigue testing. Compared with the Weibull method which is usually used in bearing life tests, the staircase method can reduce testing time. In 0rder to study the possibility of application of the staircase method in bearing life tests, experiments on the 51 103 thrust ball bearings were conducted. It is confirmed that the expected values of the mean and standard deviation estimated from the results of 20 specimens based on the staircase method approach the population parameters. In this study, it is verified that the basic dynamic load rating obtained by the staircase method was similar to that obtained by the Weibull method and that obtained from calculations according to ISO 28l: 1990. Compared with the standard deviation estimated by the staircase and Weibull methods, the results obtained by boundary and arcsin methods had larger values.

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Pressure distributions in the oil film of a porous journal bearing are investigated theoretically and experimentally under hydrodynamic lubrication conditions. The circumferential boundary condition for the oil-film pressure is obtained by applying an integral momentum equation to the oil-film region in the bearing clearance. The oil-film pressure distributions are numerically solved using this momentum equation and taking into consideration the balance between oil fed into the clearance and that lost from it. The present analysis shows the occurrence of a negative film pressure before the trailing end of the oil-film region. The experimental results confirm the existence of this negative film pressure. Furthermore, the angular position of the end of the oil-film region obtained in the present analysis moves toward the downstream region, yielding better agreement of the measured and calculated film regions than those found in our previous analysis using the quasi-Reynolds condition.

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Wear mechanisms of alumina ceramics in unlbricated rolling-sliding contact were investigated based on observation of wear surfaces and wear particles using a scanning electron microscope. Wear particles can be divided into two types, namely powder like wear particles and plate like ones. The sizes of powder like or plate like wear particles are generally on the order of sub microns or several hundred microns, respectively. Powder like wear particles are compacted on the roller surface in the process of repeated contact and form a tribo-film, whose thickness changes up to several microns depending on slip ratio. Tribo-Film delaminates partially as plate like wear particles by propagation of cracks after repeated contact. As a result, formation and delamination of tribo-film control the wear process of alumina ceramics in unubricated rolling-sliding contact.

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SiC whisker reinforced plastics severely abrade the surface of contact materials. The wear characteristics of SiC whisker reinforced plastics and contact materials are investigated in this study. It was clarified that the wear of hardened die steel is minimized by adding graphite to the SiC whisker composite and aligning the whisker parallel to the contact surface, and maximized by aligning the whisker normal to the contact surface and applying oil lubricants. Furthermore, the wear of a SiC whisker composite is minimized by aligning the whisker normal to the contact surface and applying oil lubricants. By applying the condition of maximum wear of hardened die steel and minimum wear of a SiC whisker composite to the surface finishing process, a very fine surface finish with surface roughness of 2nmRa was obtained.

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To solve ultra-thin gas lubrication problems encountered in analyzing a running surface coated with giant molecule lubricant film, a new lubrication model is derived. In this model the liquid lubricant film is replaced with permeable material, and the boundary between gas and liquid is subject to two kinds of velocity slippage: one due to rarefaction effects and the other to porous effects. Using this model, a rarefaction-modified Reynolds equation is derived considering the permeability of the running surface. Then, this equation is applied to lubrication of a magnetic head slider flying over a magnetic medium. It is found that there exists an interesting condition wherein total apparent slippage seems to disappear due to the cancellation of the two slippages, and that permeability effects are larger for a slider having a steeper pressure gradient.

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In this paper, in order to develop a more efficient and more convenient Procedure for the strength design of a spur gear, substantial effort is devoted to improving the accuracy in the boundary integral equation analyses. First, corner problems associated with a gear tip are mathematically avoided by adopting Priwalow's formulae. Next, a systematic technique using higher-order shape functions is proposed for the numerical evaluation of singular integrals. Then, a Stieltjes integral is used to deal with a discontinuous change of the boundary direction a corners. The accuracy is investigated using some numerical examples and comparison is made with the results in previous reports.

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In the previous papers, a boundary integral equation was formulated for a semi-infinite plane having a gear tooth shape on part of its boundary. In order to construct a more versatile and general-purpose procedure, the fundamental problem for the infinite plane with a hole that also has a gear tooth shape on part of its boundary is shown to be solvable by a method quite similar to that discussed before. 0n the basis of the Boundary, Integral Equation Method (BIEM) derived in this paper, it can be concluded that the approach proposed has the advantage of a precise, reliable and simple numerical solution of the semi-infinite and infinite problems of gear tooth strength rating. It is also shown that this newly developed method is applicable to other infinite problem with a hole having any profile.

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Before the calculation of speed variation in Oerlikon-type spiral bevel gears under running conditions, the tooth deflections due to a concentrated load must be clarified. In this paper, tooth deflections of a rack model were calculated by means of a three-dimensional finite-element method. Based on some characteristics of deflections which were determined from the calculated values, a practical formula for tooth deflection of the 0erlikon-type spiral bevel gears was derived. The values derived from the practical formula agreed with those calculated ones from a full model of the gear by F. E. M.

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The CNC gear-measurirng machines of today are not designed for measurement of conical involute gears. However as the design and production method of conical involute gears has advanced and the usage range of these geals has widened, the measurement of conical involute gears by CNC gear-measuring machine has become an urgent need. Therefore, a new concept called an "equivalent helical gear" is introduced, and basic dimensions of the equivalent helical gear are obtained. Thus, the tooth surface of a conical involute gear can be measured as the tooth surface of a helical involute gear by a CNC gear-measuring machine. Experiments demonstrate that this new method gives accurate results and has practical utility. Finally tooth surface analysis of a conical involute gear is alsgearssented.

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A new helical synchronous belt was developed for the purpose of noise reduction. Dimensions of the helical belts are based on the 8 mm pitch curvilinear synchronous belt, called YU, for automotive engines. The helix angles of the helical belts are 3°, 5°and 10°. In this study, the relationship between the noise and the helix angle of the helical synchronous belts is discussed. The noise level of the helical synchronous belts with helix angle of 5° and 10° is lower by around 5 dB (A)than that of the conventional synchronous belt. In the case of no load, the noise level of the helical belt with helix angle 10° is lower by about 10 dB (A) than that of the conventional belt.

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It is becoming important to modify three-dimensionally the tooth surfaces of gears in consideration of the machining and mounting errors of the gears in the manufacturing process, and of the elastic and thermal deformations of the gear teeth, gear shafts and gear casing during gear running. In this paper, the meshing characteristics of the gears with the shaft angle errors caused by bending of the gear shafts are analyzed. Firstly, two kinds of shaft angle errors are calculated when the structure and loading conditions of the gear set are given. Secondly, the transmission error and tooth bearing pattern of the gears with the shaft angle errors are calculated, which are used to evaluate whether or not the tooth surface modification is appropriate. To confirm the usefulness of this calculation method, tooth bearing tests using ground gears with modified tooth surfaces were conducted. The experimental results agreed with the calculated ones for the most part.

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In the present investigation, using a rolling contact fatigue testing machine, the surface durability (pitting limit) of steel rollers which are case-carburized and hardened to 750 Hv is examined under rolling/sliding conditions. Four kinds of rollers which are finished to a surface roughness of about O.2μm R_max or about 3μm R_max by a cylindrical grinding machine are used. To improve the ground surface the shot peening and barrelling processes are employed and they are compared to the non-treated surface. The processes of shot peening and barrelling can be applied to surfaces with complex configurations, such as gears. It is shown that the surface durability of rollers whose surfaces are subjected to a barrelling process after a shot-peening process is improved.

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Analytical results are presented for vibration of a wide timing belt under a moving load. The equation of motion is derived from Hamilton's principle, and approximate solutions to the basic equation are obtained using the Galerkin method. The steady-state responses are calculated using the harmonic balance method. Analytical results are presented which show the contributions of moving load position and moving load value to response curves. The response amplitude that varies with the width of timing belt. In the case of variable velocity, the response value shows very complicated behavior with pulley rotation. The response curves of vibration are greatly influenced by the moving load and the velocity.

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The hypoid gear is an excellent gear and its quality is estimated from the tooth contact pattern. In general, when the load changes under operation, the relative positions of the pinion and gear also change slightly, and the tooth contact pattern moves from the central part of the tooth surface towards the toe or the heel. It is considered that this is caused by such factors as the deflection of the housing or bearing, and assembly error. However, in all such cases a good tooth contact pattern must be maintained to transmit revolution with an exact angular velocity ratio. Therefore we study the characteristics of the hypoid gear tooth contact pattern that are caused by movement to both sides of the tooth surface. In the present report, the theoretical analysis for obtaining an accurate tooth contact pattern is described.

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The hypoid gear tooth contact pattern is usually adjusted in the central toe of the tooth surface, but when the transmission torque changes during operation, the gears and their mountings undergo very small displacement and the tooth contact pattern moves towards the toe or the heel of the tooth. Since there is yet no report that clarifies the change of the tooth contact pattern in such a case, we try to clarify the hypoid gear tooth contact analysis that applies high-order surfaces to the tooth surfaces to obtain an accurate tooth contact pattern. In the present report, the characteristics of the hypoid gear tooth contact pattern is described in detail using concrete computer simulation examples of the tooth Contact pattern.

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The objective of the present research is to develop a new type of flexible and multifunctional machine tool which is applicable to the integration of such manufacturing processes as machining, inspection and heat treatment of mechanical products. The functional requirements of the multifunctional machine tools are initially analyzed based on the questionnaire to both the users and the designers of machine tools. The basic configuration of a machine tool is proposed with the aim of realizing the functional requirements. The designed configuration has two main spindles for both the tool and the workpiece, one subspindle, and 8 rotational and linear feed axes. All the machining processes of turning, milling, 5-axis machining of sculptured surfaces, grinding, slotting and gear shaving can be carried out by the proposed machine tool without the need for manual set-ups. A simulation model and a scale model are developed to simulate the manufacturing motion processes and the set-up processes of the machine tool.

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A hydrostatic stress ratio of greater than 0.9 was proposed as one of the most significant criterion for void consolidation after closing during open die forging, on the basis of some physical modeling tests on 3.5NiCrMoV-rotor steel billet with a hole at the centerline and numerical simulation using the three-dimensional rigid-plastic finite-element method. To satisfy the criterion for void consolidation in a forging process of large rotor shafts, it was found that the use of a precooling ingot forging method for a rectangular cross-section-ingot is highly effective since the hydrostatic stress ratio at the center of the ingot remarkably increases with the increase of aspect ratio in the cross section from 1.0 to 1.8. The enlargement of width in the rectangular cross section enabled the development of the optimum maufacturing process of an ultralarge low-pressure turbine rotor shaft with 2800 mm and over diameter.

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A kind of apparatus to pick-up body-wrinkling is devised for axisymmetric sheet metal forming. Experiments with both hemisperical and flat headed punches, with various clearances between punch and die, with respect to three kinds of material, each of which has two thicknesses, are performed. Firstly the process of evolution of body-wrinkling is observed. Then the critical blank-holding force (or meridional tensile force) for all cases mentioned above is measured, and an empirical formula for it is proposed. The critical condition for body-wrinkling is formulated and introduced into the FEM program. Its effectiveness is checked by comparison with experimental results. Using this FEM system, the governing factors of body-wrinkling are elucidated.

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