Three-degree-of-freedom nonlinear vibratory systems with 1: 1: 1 internal resonance and with cubic nonlinearity are considered. Attention is focused on the responses of the systems near a primary resonance point. The systems are assumed to be subjected to a harmonic excitation on one of their three modes. The systems can be divided into two groups depending on the types of responses. In one group both single-mode and multi-mode responses are possible and in the other only multi-mode response is possible. Typical systems belonging to the former and the latter group are studied. The characteristics of their responses are discussed, and the occurrence of dynamic phenomena such as chaotic vibrations with different routes is shown. Among the phenomena some have not previously been reported on in relation to studies of two-degree-of-freedom vibratory systems with 1: 1 internal resonance.

抄録全体を表示

This paper is concerned with the ability of tanks partially filled with water to withstand earthquakes. The interest lies in rectangular water tanks, which have received little attention to date. The analysis is relatively involved and includes the derivation of the equations of motion for the vibration of the whole tank by means of the substructure synthesis method, a stochastic analysis relating the random ground motion caused by earthquakes to the random vibration of the tank, a stochastic characterization of the fluid pressure and computation of the probability of failure of the tank.

抄録全体を表示

A carbody of a highspeed train sometimes vibrates with a bending mode of less than 10Hz, which leads to poor riding quality. This paper describes a method for analyzing the vibration of a truck frame and a carbody taking account of their flexural rigidity. The vertical vibration of a carbody induced by vertical track irregularities is analyzed using the transfer matrix method. The numerical results are compared with the measurements on a Shinkansen train. The results show that this method well simulates the vibration of a carbody at higher frequencies above 10Hz compared with the classical method that disregards the flexural rigidity of the truck frame. Effects of the truck frame rigidity, wheelbase and axle spring characteristics on riding comfort are studied in detail. It is found that the effects of truck frame rigidity on riding quality are not significant but that the vibration characteristics at higher frequencies above 10Hz are affected significantly by the truck frame rigidity.

抄録全体を表示

Currently, researches and technologies concerning highly developed vibration control methodology are increasingly required in various fields such as structural design, earthquake engineering and aerospace technology. This work deals with a new type of seismic isolation system having multifunctional controllability. A mechatro damper installed in this system can be arbitrarily utilized as a passive damper, a semi-active damper as well as an active one according to the specific purpose. A hybrid isolation system that can be used as a semiactive-active damper is proposed. SMC (sliding mode control) algorithm is mainly used in the system based on the characteristics of the VSS (variable structure system). However, in the absence of SMC, active control can be introduced. Basic characteristics of this isolation system are clarified by both experiment and numerical analysis whereby the frequency response and some seismic response behaviors are obtained.

抄録全体を表示

Recently, active vibration control has been applied to some bridges and buildings. However, the control has only been used to reduce vibration of lower modes. Control methods and spillover problems have also been discussed, but little has been done in terms of analysis of the number and location of actuators. For reduction of the vibration of higher modes, it is necessary to use many actuators. In terms of industrial application, it is important to know the necessary number and optimum location of actuators in order to obtain the required vibration reduction. In this report, we discuss the relationship between the number and location of actuators and vibration reduction for stationary vibration of a simple supported uniform beam. The following results were obtained. First, vibration reduction is strongly affected by the location of the actuators. Second, vibration reduction varies according to the distribution pattern of forces. Based on the findings, an estimation technique for the vibration reduction was proposed.

抄録全体を表示

In manufacturing and research facilities which require a very low vibration environment. the active microvibration control system has already reached the stage of practical application. The next subject of research lies in enhancing the robust stability and vibration isolation performance under practical USe. Such study ensures that the spillover phenomena due to the elastic equipment mounted on the table can be avoided by letting the controller design reflect the plant modeling. In this method of controller design, high-order equipment-table dynamics, which influences each modal plant, is shaped by a compensator, and its normalized coprime factor plant is represented in a reduced-order mathematical model. We prove the validity of this design method. Also in this paper. the model matching method and H^∞ method are compared experimentally.

抄録全体を表示

Mechanical vibration signals can be approximated to the linear combination ofdamped oscillating waveforms in many cases. In this paper, a simple method is proposed for estimating the parameters of damped oscillation. First, a periodogram of damped oscillation is induced theoretically. Interpolating the periodogram, the angular frequency of the damped oscillation can be estimated accuratelly even when the length of signals is short. The damping factor of the damped oscillation is also estimated using the periodogram. From the results of computer simulation shown that the error between the estimated angular frequency and the true value is less than 10% even when the signal to noise ratio of the oscillating waveforms is equal to 0 dB.

抄録全体を表示

The damping properties of the Flexural vibration for a composite rectangular sandwich plate with a viscoelastic core and composite laminated faces are presented. The damping analysis is carried out using the Ritz method. The elastic moduli of the plate are treated as complex quantities, and the shear modulus and loss factor of the viscoelastic core depend on the excited frequency. The present complex eigenvalue problem is solved by means of an iterative procedure, and the damped natural frequencies and modal loss factors are determined. The present solutions are validated by comparison with published data. The effects of the frequency dependence on the core material, core thickness, the fiber angle and stacking sequence of the composite laminated faces upon the damping properties are studied.

抄録全体を表示

A design method is proposed for optimizing the free vibration characteristics of laminated rectangular plates by using simultaneously different kinds of design variables. The fundamental frequency is maximized as an object function. Design variables are taken to be the locations of elastic support points and the fiber orientation angles of layers. The complex method is applied to the optimization process for laminated plates with arbitrary boundary conditions, wherein the object function is calculated by the vibration analysis method previously developed by the authors.

抄録全体を表示

This paper deals with an evolutionary design method of structure using a genetic algorithm. In order to establish this method, virtual trees, which are able to adapt to various design requirements, are created in simulated environments. Assuming that the growth of the trees is a repetition of the self-similar shape of the structure (fractal), the tree growth is computer simulated in a virtual environment taking into account the effects of the sun, wind, gravity force and so on, where we introduce the concept of a "seed" representing the tree design method. Using a fractal-like calculation to translate the genotype of the seed into the phenotype of a virtual tree, one seed corresponds to the creation of a biotypical structure adapting to the environment. Using this idea, we evolve seeds representing the design methods by studying two cases: (A) stationary virtual environment and (B) nonstationary virtual environment. We examine the adaptability of seeds A and B in different environments, and demonstrate that seed B is more adaptive to changes in the virtual environment. We discuss the applicability of the evolutionary design method to the engineering design of structures.

抄録全体を表示

A method of active control using regenerated vibration energy is proposed. Typical active control consumes energy, which is one of drawbacks of active control. However, in the proposed active-energy regenerative hybrid control system, all of the energy for the actuator is supplied from an energy regenerative damper. For the control law of active control, the concept of sky hook control is applied. From experiments and numerical simulations, it is found that the proposed system could act as an isolator and it is expected to exhibit better isolation performance than a passive or semi-active controller.

抄録全体を表示

The use of direct displacement feedback control for vibration suppression of flexible structures by multiple proof-mass actuators is investigated. Closed-loop eigenvalue analysis is carried out considering the influence of actuator dynamics, and closed-loop stability is proved which indicates the stability robustness of the control algorithm. Regarding the performance of the control system, parameters of the actuator are optimized analytically using an eigenvalue criterion for one-degree-of-freedom structure and the optimum parameters are expressed in closed form as a function of feedback gain. In addition, the results of optimum parameters are generalized to adapt to control of multiple-degree-of-freedom structure. A control example of a plane frame structure is given with the actuators used either passively or actively. Simulation results demonstrated the effectiveness of the proposed control procedures.

抄録全体を表示

The most interesting aspect of piezoelectric material is that it can be used as both a sensor and an actuator. In this study, we attempted to use it as a sensor and actuator simultaneously. In order to implement this method successfully, we had to solve two problems. The first was to input the control signal to the simultanetously used piezoelectric element. The second problem was to separate the signals; the sensor signal due to the bending vibration and the input control command signal. This problem was resolved by introducing a dummy piezoelectric element. In this paper, the effectiveness of the simultaneous use for a control system is demonstrated by the substantial reduction of the sound pressure level in experimental results of the active control.

抄録全体を表示

An automobile simulator experiment was carried out in order to develop a method of prediction of sleepiness based on mainly physiological parameters. Twelve subjects participated in the study. First, criteria variables of sleepiness were investigated since such variables have not been clear in many previous studies. Rated sleepiness based on facial expression was examined as a criteria variable in this research. Rated sleepiness by two examiners gave high correspondence (0.755), and mean correlation coefficient between this rated sleepiness and the subjects' self-rating sleepiness was also high (0.794). These results show that this rated sleepiness is considered to be reliable and valid as a criteria variable. Second, both physiological parameters and the driving performances were adopted as explanatory variables. Cross-correlation analysis between the rated sleepiness and these parameters showed that α/β at posterior-midline (Pz), blink duration, the rate of long blink and heart rate were relevant as general indexes of slepiness. Methods of prediction of sleepiness based on these results are mentioned in our second report.

抄録全体を表示

The usefulness of various physiological and other indexes for prediction of changes in driver sleepiness during driving of a car was examined in automobile simulator experiments. Based on the results presented in our first report, a multiple regression model for prediction of the sleepiness independent of individual differences was developed. Using the relative energy (α/β) of an electroen-cephalogram at the posterior-midline (Pz), blink duration, and heart rate as explanatory variables, we obtained a mean multiple correlation coefficient of 0.697. We then developed a practical doze prevention system for drivers. Blinking was selected as the physiological parameter since blinking is measurable without direct contact. The practical prediction indexes of sleepiness were the blink duration and the rate of long blinks. The mean correlation coefficient by the prediction model that adopted the rate of long blinking as an explanatory variable was 0.705, while that obtained using the model with blink duration as an explanatory variable was 0.710. Through use of both of prediction models in combination, subjects' (N=10) sleepiness was predicted before reached a level considerd to be dangerous for in driving of a car. Based on these results, a flow chart of the process from the prediction of sleepiness to the sounding of an alarm for drivers was constructed.

抄録全体を表示

Output characteristics of a thin-film piezoelectric acoustic emission (AE) sensor array (sputtered ZnO, 0.1×0.1 mm) fabricated on a 2-mm-long Si slider for detecting head-disk interactions in hard disk drive systems were determined. The output characteristics were compared with those of a bulk AE sensor (0.7×0.7×1.0) attached to the back of the slider. Sensitivity of the thin-film sensor was about 1.7 mV/N, almost half of that of the bulk sensor. The thin-film sensor could detect AE waves caused by the contact force about 1.7 mm away from the sensor. When the slider contacted a bump on the disk, the output waveforms of the thin-film sensor were almost the same as those of the bulk sensor, and the noise level of the thin-film sensor was lower than that of the bulk sensor. Output signals of the array sensor matched the slider flying height at the position of each sensor.

抄録全体を表示

This paper deals with a design method for a PID adaptive controller based on frequency domain analysis. The method is based on the estimation of a nonparametric process model in the frequency domain. The PID controller parameters are determined by achieving partial model matching so as to minimize a loss function concerning relative model errors between the loop transfer function of the control system and the reference model system. The process is represented only by a discrete set of points on the Nyquist curve of the process. Therefore, it is not necessary to estimate a full order parameterized process model to design a control system.

抄録全体を表示

This paper deals with the identification of parameters related to DC servomotor systems. Generally, it is considered that the parameters of DC servomotor systems can be simply identified by means of the least mean square method. However, because of the mutual effects of Coulomb's friction and the viscous attenuation force, the accuracy with which these parameters are identified depends on the applied input signals. In this paper, using the inertia, viscous attenuation factor and solid friction in a DC servomotor system as identification parameters, the above phenomenon was confirmed, and the identification results were indicated precisely. Finally, an evaluation of the identification method of the parameters is discussed.

抄録全体を表示

Three-dimensional (3D) visualization is a key component in the human interface for teleoperation. A 3D visualization system usually implies a system which uses convergence and binocular parallax. It has been found, however, that spatial sensitivity using these techniques is highly inconsistent among individuals. In this paper, we discuss the presentation of the movement parallax (MP), which is another aspect of 3D visualization. In order to present MP, the display device must follow the movements of the human's head. A natural choice here is to use a head-mounted display (HMD). For practical teleoperation, however, a HMD is found to be too stressful for the operator. In this paper, we propose a technique to present MP on a large fixed screen. A prototype is developed, and experiments show that the MP is very effective in improving the operator's ability to recognize the teleoperation environment.

抄録全体を表示

This paper deals with a theoretical instability analysis of a rotating flexible disk subjected to swirling fluid flow in a confined fluid, and an instability mechanism governing the unstable vibration where the dissipation effect of structural damping and fluid viscosity are disregarded. In the instability analysis, the basic equations of swirling fluid flow around the rotating disk are derived by integrating Navier-Stokes equations over the gap width between the rotating disk wall and the shroud wall. The structural vibration equation of the rotating flexible disk is based on the Kirchhoff-Love plate model neglecting structural damping. The equations of coupled fluid-structure motion take into account the moving boundary conditions with respect to both the rotating disk and the fluid flow. These equations were linearized for small deflections of the disk near the equilibrium state, and the solution of these equations is obtained by using the multimodal expansion approximation and applying Galerkin's method. Instability is defined as the condition of a negative imaginary part of complex eigenvalues in the characteristics equation. The instability mechanism governing the unstable vibration is sufficiently understood. It is found that the characteristics of the unstable vibration are dependent on the added mass parameter.

抄録全体を表示

An improved design scheme of a model reference adaptive control (MRAC) for a pneumatic servo system with additive external forces is presented. In this design scheme, the difference process for the identification signals is adopted in the identification mechanism for elimination of the influence of the constant disturbance caused by the additive external forces. Furthermore, the controller of this design scheme is constructed with a compensator for overcoming the influence of the disturbance. As a result, the satisfactory control performance can be achieved.

抄録全体を表示

We propose a method for recognizing a subject from the image taken by a CCD camera and comparing with the CAD figure. The three-dimensional CAD figure is transformed into a two-dimensional figure in which some color is added inside the contour. The transformed figure is used as the input of image processing. The two-dimensional CAD figure and an image of the recognized subject from one camera are represented by characteristics, that is, the center of gravity, contour, the distance between them, and FFT. The figure of the subject is estimated from these characteristics by comparing with the database of CAD figure.

抄録全体を表示

In this paper, space and picture models for machine vision in railway were developed. The railway space is modeled as an imaginary rectangular tunnel including the construction gauge. The walls of the imaginary tunnel are mapped with wall pictures representing wayside facilities and a background landscape. The wall pictures are quasi-normalized along the railway axis. Using the model, we can transform a point in a wall picture into a point in a perspective picture taken by a camera. Consequently, the wall picture and the perspective picture can be transformed, each from the other. We can estimate the mapping error corresponding to deviations between the actual point and the wall. Additionally, some applications showing the effects of this model are illustrated.

抄録全体を表示

This paper describes a design method for applying nonlinear robust control to a two-point-support magnetic levitation system on a flexible beam. The beam investigated here is assumed to be flexible enough that the gravitation causes noticeable static deflection. A unified dynamic model including static modes is introduced and an exactly linearized state equation system is derived by use of the feedback linearization technique. A direct output feedback controller is applied to the sensor/actuator colocated system, and an H^∞ robust control system is applied to the linearized systems to compensate for modelling errors. The experimental results proved the effectiveness of the proposed design method.

抄録全体を表示

This paper is concerned with a design of a digital adaptive control system for a nonminimum phase system with an unknown time delay. In the case of continuous time controlled systems having a nonminimum phase characteristic, discrete versions also have the characteristic. Furthermore, if the sampling period is sufficiently small, discretized continuous time minimum phase systems with a relative degree larger than 2 become nonminimum phase systemS. We have proposed a design method of an adaptive control system consisting of a pole placement controller, and series and parallel compensators which compensate unstable zeros. >From experiments of the position control of an underwater pendulum with an undershooting phenomenon, the method is effective to the nonminimum phase systems. Here, we extend the method to the case of unknown time delay systems. The proposed method guarantees the stability and convergency of the adaptive system. In order to verify the validity of the method, simulations of minimum and nonminimum phase systems and experiments of the position control of an underwater pendulum are given. The simulation and experimental results show the high performance of the constructed adaptive control system and the effectiveness of the proposed method.

抄録全体を表示

In the previous papers, the authors proposed an active periodic noise control system using the filtered-x adaptive notch filter with a minimum amount of calculation. In this work, a method of improving for active noise control performance is presented for an application with multiple reference signals. Four-cylinder diesel engine noise inside cars contains fundamental and high-order harmonic frequencies. We apply active noise control for the five fundamental harmonic frequencies of diesel engine noise. When other order frequencies with amplitudes larger than those of the controlled frequencies are contained in the noise, the noise reduction effect is reduced because of interference with these frequencies in the adaptive notch filter. We solve this problem by adopting the spectrum-shaping method. This method consists of dividing the bandwidth of interest into low- and high-frequency regions using band-pass filters. This method is useful for suppressing coupling with harmonic-order frequencies and makes the control performance much better.

抄録全体を表示

We describe a design method of evaluating robust stability of a filtered-x type adaptive notch filter which can be executed by performing only a few calculations for periodic noise such as engine noise. The algorithm needs to obtain the identification model of the acoustic transfer function by using different notch filter for each control frequency. However. a modeling error increases in the frequency range where both gain and phase of the acoustic transfer function varies largely, so that leads to an instability. For the purpose of maintaining stability, we propose a method that classifies a modeling error into gain error and phase error and stabilizes the system by evaluating allowable limit for each error in all control frequency range. Theoretical analyses and computer simulations based on introduced equations reveal the following. Even if gain error exists. the system can be stabilized by adjustment of the step size parameter. On the other hand. even if phase error exists, the system can be controlled in a stable manner by obtaining all identification models at frequency intervals where phase deviati on is less than 90 degrees. Moreover, the design method of guaranteeing robust stability can be developed clearly in the paper.

抄録全体を表示

This study presents a new architecture of neural networks named the cubic neural network (CNN), which possesses a multilevel structure and uses parallel distributed signal processing as an intelligent control method. This CNN enables abstracting of signal processing, and each level of neural networks processes a different degree of abstracted signals. In this paper, an expanded architecture is suggested in which several CNN are integrated to control objects which have intensive nonlinearity or plural purposes. As an example, the swing up and stand up control of a pendulum is illustrated, and the usefulness of the present method is shown.

抄録全体を表示

Ambulatory capability is necessary for the self-support of the aged. Therefore we proposed the walk training system for walk rehabilitation. A walk training system for the aged is now under development. It has two parts: a training environment and a patient support element. The training environment comprises a treadmill and a display. In this paper, the control method, parameter estimation and experiments are described. We introduced a new control method for a treadmill of the walk training system, which uses active impedance control. The velocity of the treadmill is changed by kicking force from a trainee on the treadmill. Thus a trainee can walk at a speed which he can cope with. The treadmill has two endless belts driven by servo motors, one for each of the trainee's legs. Thus, the trainee can use the treadmill even if his or her two legs are not of equal ability, for example a post-stroke hemiplegia.

抄録全体を表示

The optimal regulator is a key device in modern linear control theory. This paper deals with a problem of computation of the output feedback gain which minimizes the quadratic performance criterion. Numerous methods of computation of the output feedback have been presented in other reports, but they all require iterative calculation. However, use of such iterative algorithms requires solution of nonlinear matrix equations. Furthermore, the conditions for the existence of the output feedback gain which satisfies an algebraic equation are unclear. In this paper, a low-order model for computation of the feedback gain is proposed. This method is based on the second method of Lyapunov. The computational method for the output feedback gain and comparison of the Lyapunov functions of the original system and the low-order model are presented. This computational procedure does not involve use of any iterative algorithms. We have identified the conditions for the existence of the output feedback gain and the sufficient conditions for attainment of the optimal solution.

抄録全体を表示

What kinds of functions the dual arm cooperative task controller must have is considered and concluded as followings. The controller must be able to control the relative movement of both hands and the working position of task, and autonomously determine the working position by choosing one criterion from at least two criteria that conflict each other. It is expected that the trajectories of the arms are continuous even if the controller change the criterion. Additionally, the working position need not be strictly optimal. The previously presented papers have not satisfied all conditions shown above. In this paper, the new controller that can accept the desired trajectory of relative movement of both hands and autonomously determine the working position in real time is proposed. It is shown that the proposed controller satisfies such conditions and works effectively by the experiment in which the dual arm robot holds, bends and breaks a wooden chopstick.

抄録全体を表示

A cooperative control approach between human and robot is important for carrying out various tasks in a hazardous environment, including space. In this case, the robot is operated based on a cooperation of direct human control and autonomous robot control. In this work, a process of cooperation between human control and autonomous robot control using a neural network for optimization of the degree of cooperation between human and robot is proposed. The proposed control system complements the judgment ability of the human operator to fuse the recognition ability of the human operator and the sensing functions of the robot. The degree of participation of the human operator in the control is determined based on a reference cooperative model which expresses the desired human and robot cooperative form. In experiments, contacting tasks for various object walls were performed by a two degrees of freedom Cartesian robot. The results indicate that the proposed cooperative method can be used for successful cooperation of human and robot.

抄録全体を表示

The advantages of applying sensorless control to mechanical systems are cost reduction, prevention of instability of the control system by collocation, noise reduction, decrease of breakdown frequency, increase of reliability and space saving. In this study, we deal with a sensorless positioning control problem of a single-link robot arm with nonlinear friction torque at the drive system. The state of the system is estimated by means of an observer from the angular velocity obtained indirectly from the coil current of the motor to drive the arm, and controlled by a controller. In order to realize such a control system, robust performances are required in the state estimation in addition to the control law. We combined a sliding mode observer and a sliding mode controller to construct a nonlinear robust control system. Then, we applied it to the motion control system of the robot arm. Finally, we investigated the performance with regard to positioning control of the arm.

抄録全体を表示

In this paper, a trajectory tracking control method for a flexible wheeled-type mobile robot is described. The flexible mobile robot consists of a wheeled-type mobile mechanism and a flexible structure. The flexible structure consists of four flexible beams and a bench. The mobile distance is measured by an encoder. and a laser sensor is utilized to measure the flexural displacement of the flexible structure. Then. the trajectory tracking control system is constructed with the disturbance observer and the feedforward compensation type two-degree-of-freedom control method. Furthermore, the experimental results confirm that the trajectory tracking control of the bench of the flexible mobile robot can be performed successfully by the present control method.

抄録全体を表示

Translational motion control of a parallel biwheel vehicle (PBV), which is driven with a stepping motor operated in an open-loop mode, is described. The posture of the PBV is regulated by a discrete time sliding mode controller. A zero point offset on the inclination angle of the PBV is introduced to trigger and to control the translational motion of the PBV, since a conventional sliding mode servo system is not controllable if the angular velocity of the PBV wheel is selected as the reference input. The velocity and position of the PBV can be regulated through the offset by additional PID and PD controllers. For a bipolar square wave velocity reference, the velocity of the PBV can quickly follow the reference signal and the PBV can run with fairly constant velocity. For a bipolar square wave position reference, the PBV shows a fast step-like response followed by a somewhat slow one bound on a sliding surface. A conflict between the PID and PD motion controllers and the discrete sliding mode posture controller occurs when the position of the PBV settles toward the reference position.

抄録全体を表示

We present a vision-based navigation system which has an error recovery function for an autonomous mobile robot. A misrecognition of the landmark causes the robot to mislocate itself. When this happens. the robot is unable to perform its primary objective. In order to solve this kind of problem, we have proposed a hierarchical control architecture. "HALAS" (Hierarchical Adaptive and Learning Architecture System). HALAS consists of modules which are arranged hierarchically and each module represents a single function of this robot. When one module fails in its aim, the upper module detects the error and recovers from it using other useful information from its knowledge data base. In this paper, we show experimentally that the robot gets a heigher reliability in autonomous mobility because the Map Correspondence Module finds the error which has been caused by an Anemo Perception Module (landmark recognition module) and it corrects the error utilizing its map information.

抄録全体を表示

This paper presents a study on the effects of design parameters (rim thicMness, standard pressure angle, number of teeth, and face width) on root stresses of a meshed thin-rimmed helical internal gear with an asymmetric web arrangement for a planetary gear unit of the automatic transmission of automobile. The tooth deflections of the thin-rimmed helical internal gear with an asymmetric web arrangement of various design parameters due to a concentrated load were calculated by the three-dimensional finite-element method (3D-FEM). On the basis of the calculated results, approximate equations for the influence function of the tooth deflection were derived. The load sharing factor and the load distribution on the contact line of the thin-rimmed helical internal gears in mesh were calculated using these approximate equations and Kubo and Umezawa's method. The root stress of the thin-rimmed helical internal gear under the distributed load was calculated using the 3D-FEM. and the effect of the design parameters on the root stress was determined. Furthermore, a practical formula for the maximum root stress of the thin-rimmed helical internal gear with asymmetric web arrangement in mesh was derived.

抄録全体を表示

In this study, using two kinds of bevel gears (straight and skew) with a power-circulating-type bevel-gear testing machine, the fillet strains. the torsional and bending vibrations of the gear shaft and the vibrating displacement in the axial direction are measured under a constant transmitted torque. In comparison with these measured data, the difference in dynamic behavior between straight and skew bevel gears is investigated The conclusions are described as follows. When the mesh frequency increases, the fillet stress ratio of the straight bevel gears increases markedly, but that of the skew bevel gears increases in small increments. The amplitudes of the components of the torsional and bending vibrations of the gear shaft, and the vibrating displacement along the axial direction on a skew bevel gear are smaller than those of the straight bevel gears. The components of the higher frequency zone. such as 3 fz, and 4 fz, scarcely appear in the displacement of the skew bevel gear along the axial direction.

抄録全体を表示

A new method of tooth profile synthesis using vector equations for derivation of the tooth profile of a gear from the given tooth profile of the mating gear is proposed. The ideal tooth profiles of conical-external and-internal gears which engage with the inclined cylindrical-involute gears over the entire tooth width were derived using the proposed method. Moreover, the tooth profiles in a plane perpendicular to the axis of the inclined cylindrical gear were derived from the obtained ideal tooth profiles, and their characteristics were investigated. The following results were obtained: (1) the tooth profiles of the conical-external and-internal gears are almost equal to the involute curves in the plane perpendicular to the axis of the inclined involute gear; (2) the radii of the base circle of the involute curve are given by the equivalent tooth numbers of the conical-external or-internal gear; (3) the profile-shift coefficient is given by the center-to-center distance between the inclined involute gear and the conical-external gear, or between the cylindrical gear and the conical-internal gear; (4) the profile-shift coefficient changes nonlinearly along the axis of the cylindrical-involute gear.

抄録全体を表示

The authors previously proposed the boundary integral equation method (BIEM), whose integral equations were formulated from the viewpoint of the two-dimensional theory of elasticity, and applied this method to stress and displacement analyses of single connected domain problems such as thick-rimmed external and internal spur gears. For the purpose of the further development of BIEM, we present ways of improving the analytical accuracy and the procedure for solving multiply connected domain problems. In this report, a thin-rimmed spur gear with circular holes is analyzed as one of the multiply connected region problems and the calculated results are compared with those obtained by the boundary element method (BEM). It has been said to be difficult to solve such complicated problems using traditional methods based on the two-dimensional theory of elasticity. However, stress and displacement distributions of thin-rimmed spur gears can easily be analyzed by BIEM under the condition that its model has a semi-infinite gear tooth domain with circular holes. As a result, it is shown that this new method, is applicable not only to single connected domain problems but also multiply connected domain problems.

抄録全体を表示

Stepped thrust gas-film bearings are widely used for high-speed rotating machinery due to their simple structure and high load-carrying capacity. In such bearings, the fluid inertia forces may play an important role under high-speed operation conditions. This paper describes the effects of fluid inertia forces on the static and dynamic characteristics of stepped gas-film bearings. In the numerical analysis, the pressure distributions in the pocket and land regions are evaluated from the generalized Reynolds equation considering the centrifugal force. The pressure values at the step are calculated by considering the conservation of mechanical energy and the continuity of fluid flow in the pocket and land regions. Moreover, the dynamic response of the bearings subjected to impulsive and sinusoidal excitations are analyzed for different values of film thickness ratios. From the numerical results. the effects of fluid inertia on the static and dynamic characteristics of high-speed, stepped thrust gas-film bearings are clarified.

抄録全体を表示

In order to characterize the power transmitting state of a continuously variable transmission (CVT) using metal V-belts, mean coefficients of friction between blocks and pulleys, and between the blocks and rings, are introduced. The present approach is primarily based on the classical Euler's equation for conventional V-belts. The existence of idle and active arcs is taken into consideration by adjusting the coefficients of friction, since the power is assumed to be transmitted through all the contact arcs of the belt in this study. The power transmitting mechanisms induced by the estimated mean coefficients of friction are highly consistent with the data measured by the sensors made by blocks. The mean coefficients of friction also have some universal trends with respect to transmitted power, torque ratio, speed ratio and so On. The mean coefficients of friction would be applicable not only for characterizing the power transmitting state, but also for designing a CVT using metal V-belts.

抄録全体を表示

Free surface profiles of aluminum sheets under equi-biaxial tension are examined by employing three kinds of fractal analyses, i.e., the zeroset, power spectrum and box-counting methods. With an increase in plastic strain. long-wavelength components of the surface profiles become dominant, and their fractal structure tends to be constant beyond a certain strain. It is found that the surface roughness and fractal dimensions depend on the equivalent strain, independent of the stress ratio. A method for simulating the surface roughening behavior is presented by utilizing the power spectrum method.

抄録全体を表示

The combined effects of the forming factors on the deep-drawability of square cups were studied. Blank shapes, tool shapes and blank materials were used as the forming factors. The circumferential distribution of meridian tensile stresses along the contour of a square cup during deep-drawing highly influenced the deep-drawability and was related to fracture types of drawn cups. Several characteristic lines for fracture forces and drawing forces were used to estimate the deep-drawability. The force lines, which were found in the figures of the relationship between fracture forces, drawing forces and blank shape, were affected by the blank materials and tool shape. The combined effects of the forming factors on the deep-drawability were characterized by these lines. The constant fracture force and the transition fracture force could be a measure of possible improvement for deep-drawability.

抄録全体を表示

In order to verify the accuracy regarding contact and friction, the two-dimensional (2D) penalty rigid-plastic FEM program (which was developed in previous reports) is applied to the ring compression problem. Then a 3D FEM code is developed by extension of this program. Using this code, the fiat-tool compression and spherical punch indentation of a block of various materials under various friction conditions are carried out. At the same time, the occurrence of fracture and change of relative density during deformation are inspected by using the Oyane's ductile fracture criterion and the change of relative density calculated by this code. From the results. this code is confirmed to be effective. Furthermore. it is shown that fracture is dependent on the forming type, material and friction condition, and that the prediction of fracture from the trivial change of relative density is possible using this code in which compressibility is not taken into account.

抄録全体を表示

One of the forming methods to reduce weight and save material in laminated products is stretch draw ironing combination forming. This combination dry forming process is carried out without using a coolant/lubricant because of the good sliding property of the polyester film. The main purpose of the stretch draw ironing method is to reduce the cup wall thickness by more than 30% without damaging the laminated film. From the experimental results, the decrease of the forming load related to wall breakdown can to obtained by setting the initial draw ratio to be larger and the 1st redraw ratio to be smaller. Higher side wall reduction and thickness can be obtained by setting the redraw die radius (Rd/to) or clearance of punch and ironing portion smaller. In particular, the influence of the ironing clearance (Cl) is marked. The ironing reduction and punch temperature are affected by the stripping-out load in removing the cup from the punch. Further reduction becomes possible by the combining the stretch draw process, which produces less damage, and the ironing, which gives greater stability.

抄録全体を表示

This paper describes a local internal crack resulting from three-dimensional slab deformation of a solidifying shell at the central bearing during high-speed continuous casting. This internal crack is not explained by the present bulging model, as we constructed a new model in which three-dimensional slab deformations at the central bearing result from the coefficient of slab bulging and the coefficient of bulging strain using the finite-element method, and calculate a two-dimensional beam model taking into consideration the elastic, plastic and creep deformations. Compared with calculations and measurements of slab bulging that were made by our experiments, we found that this model could be used to analyze three-dimensional slab bulging and to design a high-speed casting machine.

抄録全体を表示

In this study, a method to measure workpiece size errors due to grinding wheel wear for NC grinding machines and their compensating method are proposed. In this method, workpiece size errors are measured using the contact signals between the grinding wheel peripheries and a single point diamond dresser in the dressing process, and using an NC dressing program, the worn parts of wheel peripheries can be distinguished from other parts by on/off signals of an AE sensor located behind the dresser. According to the experimental results, it is shown that workpiece size errors can be identified in the resolution corresponding to the least incremental input of NC signals using the NC machine. Furthermore, applying the relationship between AE signals and workpiece size errors, a new automatic workpiece sizing cycle is proposed, and its usefulness is experimentally confirmed.

抄録全体を表示

In order to reduce the aerodynamic noise of a lathe chuck, the air flow around the three-jaw scroll chuck is observed by means of the tuft and smoke wire methods. Flow visualizations are carried out for various cases, e.g., that without a workpiece, that with cylindrical-and flange-shaped workpieces, and that when the chuck rotating speeds are 1 000, 2 000 and 3 000 rpm. The investigation shows that the air flow around the chuck consists of four flow patterns, i.e., axial flow from the tailstock to the headstock, entrained flow within the area enclosed by top jaws, flow from the front to radial areas of the chuck and flow corresponding to the velocity boundary layer caused by the rotating chuck.

抄録全体を表示

Pressure and frictional stress acting on the ripper point surface have been directly measured in the actual rock ripping process using stress sensors embedded in the top part of the ripper point. In the case of ripping sand stone ground, applied stresses are relatively low but sometimes increase rapidly, unless the traction force is constant. In the case of ripping conglomerate ground, large stress is applied to the top of the point surface and changes in proportion with the traction force. Point surface temperature has been also measured using an embedded temperature sensor. The temperature increases intermittently during the ripping process.

抄録全体を表示