Excessively large transient torsional vibration is induced on the rotor system of modern large turbine-generators. This paper reveals that the coupling connecting the adjacent rotors acts as a hysteresis damper, and discusses the effect. First, a model is presented for the damping mechanism of typical shaft coupling. Second, the time-dependent nonlinear transient torsional vibration of the rotor system is investigated, using this model. Third, an improved coupling of higher damping capacity is introduced and investigated in the same way. Thus, the proper direction of the optimal design of coupling is clearly specified.

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In resonance of a finite group of blades, stress increasing and decreasing effects often occur. As the first step in the elucidation of the cause of these effects, this paper thoroughly investigates phenomena related to these effects, from a broad perspective. The natural frequencies, normal modes and resonant stress ratio of the first-order tangential flexural vibration of a finite group of blades are calculated by means of Rayleigh-Ritz method, for a very wide range of the thickness ratio between the shroud and blade. The results indicate that, (1) the elastic curves of the blades are identical or similar in each normal mode, (2) the resonant stress increasing and decreasing effects are not related to the form of the blade's elastic curve in the normal mode, but are only related to the ratio of the blades' amplitudes in it, i. e., the waveform of vibration, and offer a sound base for the theoretical investigation of the cause of these effects, which is reported in another paper.

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The previous paper revealed that the vibration waveform of the grouped blades is the cause of the resonant stress increasing and decreasing effect, and provided the theoretical investigation with a set of fundamental data on the tangential flexural Vibration of the finite group of blades. This paper, which aims to clarify the cause of the above effects theoretically, first investigates the resonant response characteristics of the infinite group of blades, whose vibration waveform is inevitably a sine waveform, and finds that the infinite group of blades has neither resonant stress increasing nor decreasing effects. This suggests that these effects result from the deviation of vibration waveform from the sine shape. Therefore, this paper also investigates the data provided by the previous study in detail, and confirms the above suggestion, and presents a straightforward method of distinguishing the normal mode of the resonant stress increasing effect from that of the decreasing effect, together with a straightforward method of estimating the degree of those effects. Finally, it is discussed which is superior between the infinite and finite groups of blades, from the viewpoint of the resonant stress increasing and decreasing effects.

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In this paper, a seismic base-isolated table with a rotational inertia mass and nonlinear restoring force is proposed. The table is supported by ball bearings and produces restoring force by means of a rope and pulleys. The nonlinear dynamic characteristics of this table are investigated analytically and experimentally. The results obtained here are summarized as follows. ( 1 )The developed analytical model of this table has been examined and proved to be valid through comparison between the simulations and experiments. ( 2 )It has been proved that the input seismic acceleration from ground motion to the table was lost due to the effect of the installed rotational inertia mass. ( 3 ) The waveform of acceleration obtained from the dynamic experiment showed keen spikes due to the effect of the nonlinear characteristics of this table, and this phenomenon has been clearly, analyzed by the method of harmonic balance.

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Taylor series approximation (TSA) has been used to form an approximate subproblem to the actual design problem for efficiency. The nonlinearity of bucklind and natural frequency constraints has required imposition of strict move limits or high-quality approximation. A new approximation method for the eigenvalue constraints of stiffened plate and shell structures is suggested, and the efficiency of minimum weight design is discussed. The approximation suggested here is based on the Rayleigh quotient approximation (RQA) and improves the quality of the approximate eigenvalue constraints by approximating the modal strain and kinetic energies instead of the eigenvalue itself. The approximate subproblbm is solved by a sequential quadratic programming method. Numerical examples show that the Rayleigh quotient approximation achieves stable convergence with generous move limits.

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In the first report, we proposed digital simulation methods which can account for compressor-piping interaction. These methods assume that the stiffness of gas in the compressor cylinder is constant. This paper describes the new compressor model in consideration of the nonlinear stiffness of gas in the compressor cylinder, in which, as in practical compressors, gas stiffness varies with the movement of the piston and the suction/discharge gas flow from/into the piping. By using the present model, the digital simulations were carried out for a compressor-piping system. From these calculations, it is shown that the present method can also deal with compressor-piping interactions, in comparison with the simulation results in the first report.

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Active vibration control requires structural velocity as a feedback signal to reduce the peak resonances. Sometimes, it is very diffcult to install the sensor at the same position of the actuator. Moreover, setting the usual gap sensor close to the magnetic actuator may cause undesirable interraction between them. The noncontact gap sensor detects displacement, which requires a differentiator to produce the velocity. In this paper, a moving-coil-type electrodynamic actuator is tested as a two-port sensing and driving device with good linearity and high efficiency. A method to identify pure back-electromotive voltage is developed, which is utilized to reduce the resonant peak of a single-degree-of-freedom system.

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This paper presents the active viblation control of a cantilevered pipe conveying fluid. The response of the cantilevered pipe controlled by the torque produced by a pair of tendons attached to the pipe and a servo motor. The equation of motion is solved by means of the Galerkin method. In order to reduce the number of system mode, a suboptimal control law considering the effect of spillover is applied to the system. The experiment was performed by using a long flexible pipe conveying water, which was hung horizontally by six supporting strings, Numerical simulations and experimental results are in good agreement with each others and show that this method is effective for suppresion of the flutter of the cantilevered pipe conveying fluid.

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Hydraulic engine mounts are replacing conventional rubber mounts in order to provide better ride quality and to reduce noise. In this paper, a real-time semi-active control method of hydraulic mount damping is presented. Although it is desirable to use the state of fluid motion as the feedback signal, it is difficult to measure this mortion directly. As an alternative, a simulator which estimates fluid motion from the measurable vehicle vibration is developed. However, real-time control is limited by the speed of computation; thus it is of interest to find optimal numerical integration algorithms. Of the Euler, Adams-Bashforth, Runge-Kutta and central difference methods, the latter method is the most feasible for this application because steady-state error becomes negligible even with large sampling periods. It is demonstrated experimentally that this simulator is effective for vibration control.

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In this paper, an analytical method for estimating the capacity of energy absorption of a structural system with a hysteretic restoring force subjected to seismic excitation is proposed. Using a single-degree-of-freedom system with bilinear restoring force, the conventional equation for calculating the capacity of energy absorption has been presented by applying the method of equivalent linearization, which represented the reduction of input energy due to the absorbed energy of the hysteretic restoring force. Finally, it is clear that the calculated capacity of energy absorption by the proposed method almost agrees wih that obtained through the response analysis using several real earthquake motions.

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The method previously developed for obtaining eigenvalues of the two-dimensional Helmholtz equation by the boundary element method is extended to apply to the three-dimensional problem. The following two issues are theoretically investigated: i) validity of neglecting the domain integral appearing in the formulation by the Multiple Reciprocity Method (MRM), ii) the relation between the present formulation utilizing the fundamental solution of the Laplace differential operator and the formulation using that of the Helmholtz differential operator. A three-dimensional version of the MRM formulation with polynomial matrices in terms of unknown eigenvalue is presented. A few three-dimensional computations are illustrated.

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When valve positioner is surrounded by an combustible gas, the electrical control circuit must be connected with the actuator by long pneumatic tube. If the pneumatic tube exceeds a certain length, the hunting will occur to the drive shaft of the actuator due to the time delay of the pneumatic pressure signal. Though the Smith method had already been known to prevent such hunting, there are some difficulties for application. Thus, a new stabilization method is proposed to realize more simple compensating circuit. First, the approximate compensator based on the Smith method is explained. Second, the robust stability condition for such system is derived: developing the Palmor method. Uning this method, the stability margin under the identified error of time delay is clarified. Finally, through experiments, it is ascertained that the introduction of the approximate compensator makes it possible to stabilize the valve positioner.

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The rotational characteristics of an ultrasonic motor using travelling wave are analyzed by employing a simple model for driving mechanism. A travelling wave is excited in the stator of annular shape by using a piezoelectric driver and the amplitude of the effective vibration in the circumferential direction is amplified by making a number of teeth on the stator's surface. The torque-revolution relation of the motor is calculated by assuming that the rotor is driven by the frictional force acting from the vibrating stator and that the contact force on each tooth varies in proportion to the contact time to the rotor surface due to the elliptical motion of the teeth. It is shown that the calculated results are in agreement with the experiment conducted on a model motor.

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The dynamic behavior of rotational brush wheels, which are a main part of a road sweeper scavenging volcanic ash, has been examined experimentally. The vibration of polypropylene brush fibers has been recorded by a video camera and it has been analyzed to elucidate the dynamic behavior of brush fibers relative to the length and thickness of the fiber, the revolution frequency of brush wheel and the scavenging speed. Consequently, it is revealed that certain combinations of the natural frequency and wheel angular velocity should be avoided, and that scavenging speed hardly affects the dynamic behavior of the brush fiber.

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Experiments on scavenging volcanic ash with various rotational brush wheels having polypropylene fibers have been performed, changing the rotation frequency and the scavenging speed. At the same time, the wheel torque and the rate of collecting ash were measured. Consequently, it is revealed that the values of wheel torque and the rate of collecting ash decrease with unsuitable combinations of the natural frequency and wheel angular velocity. In addition, the rate of collecting ash below 100% seems to be linearly proportional to the nondimensional value of wheel torque.

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This paper presents a practical application of a method for correction of finite-element models to an actual component, called a "center beam", of automotive bodies. The applied method for correction of finite-element models is improved from a method which was previously proposed by the authors, by introducing sensitivities of natural frequencies and natural modes of interest with respect to not only thicknesses of finite elements but also material constants. The initial finite-element model of the specimen was successfully corrected, or improved in other words, with respect to the dynamic characteristics up to over 200 Hz by referring some of the lowest natural frequencies and natural modes to the experimentally obtained modal parameters under the free-free boundary conditions. It was certified that the corrected finite-element model was able to represent its dynamic characteristics well, even under boundary conditions different from the free-free conditions. From the certified results, it can be said that the correction is valid in terms of the physical considerations.

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A multiple fuzzy controller is proposed for self-organizing fuzzy control in which several "elemental fuzzy controllers" are processed in parallel and the degree of usage of each inferred consequent is determined by using a linear neural network. The inputs to the neural network are all the inferred consequents generated from the elemental fuzzy controllers, and the output of the neural network is the control input to the plant. The delta rule is used to update the connection weights for the network so that the square of plant output deviation is minimized. The present approach allows the elemental fuzzy controller to be used in situations in which the controller parameters are tuned incompletely; thus the number of trials and errors required for tuning the parameters can be decreased significantly. The effectiveness of the present fuzzy controller is illustrated by a simulation for the attitude control of a flexible satellite.

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This paper is concerned with the design of a Model Reference Adaptive Control System (MRACS) for motion with unknown nonlinear friction. From the control system viewpoint, the static friction is characterized by a nonlinear dead zone element for the control input signal. Thus, the MRACS is considered for a nonlinear system which is a cascade combination of an unknown dead zone block and a linear dynamic block. In order to verify the validity of the theoretical results, the design method described above is applied to a servo system influenced by friction. Experimental results have shown the high control performance of the constructed MRACS and the effectiveness of the proposed method.

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This paper presents a new control method by an adaptive front steering system. Two types of model reference adaptive steering systems are proposed in this paper : one type puts emphasis on yaw rate of the vehicle which a driver perceives dominantly under ordinary driving conditions : and another one puts emphasis on lateral acceleration of the vehicle which a driver perceives dominantly under critical driving conditions, such as obstacle avoidance. The parameters of the vehicle are treated as unknown and are identified by the least square method with a time variant forgeting factor. The control method used in this paper is a pole assignment type adaptive self-tuning control method. Simulation results show that the running safety is improved significantly and that the driver burden is decreased under critical driving conditions.

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Full-scale tests were conducted to investigate the movement of a shield tunneling machine in soil. First, operation data were analyzed to examine the model proposed in a previous study. Second, the control system designed by the present authors was tested in experiments. It was found that the model expressed the movement characteristics and that the control system worked satisfactorily.

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This paper presents a new identification method which utilizes fuzzy inference in parameter identification. The proposed system has an additional control loop where a real plant is replaced by a plant model. At first, an input signal, such as a step signal, is given to both control loops. Then the parameters in the plant model are modified such that the output signal features, such as magnitude of an overshoot, of the two loops become closer. Fuzzy rules describe the relationship between comparison results of the features and magnitudes of modification in the model parameter values. This method is effective in auto-tuning because the response of the closed loop is verified. The proposed method is tested both in simulations for several plants with first-order lags and dead-times, and in experiments for motor control. The results show that the proposed method is effective in practical use.

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This paper is concerned with a simulation study for dynamic behaviours of hydraulic shovels. The main purpose is to construct a CAE system which can design the hydraulic shovels on the display of computer with improved leveling control performance and operating feeling. Firstly, a numerical method to compute the dynamic behaviours of hydraulic shovels is presented by combining the dynamics of attachment and the characteristics of hydraulic circuit, assuming that the operator manipulation is modelled by the software of computer. Secondly, the execution time of leveling control on the display is adjusted to that of real shovels, by simplifying the modelling of the hydraulic circuit. Finally, the leveling control performance by operator manipulation is exactly evaluated by giving the parameter values of the hydraulic shovels.

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An intelligent monitoring device for laser welding in small-size pipes is described. It monitors the reflected laser light and the welding speed, etc, learns the normal criteria and the anomalous criteria of welding, and discriminates between normal and anomalous welding. Using the learned criteria, it categorizes the anomaly as one of several types. As a result of evaluation tests, the degree of correspondence between this device and nn expert is about 90%. This paper describes the new methods, the multivariate analysis for discriminating between normal and anomalous welding, and a neural network model for distinguishing the types of anomalies.

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It is well kown that a preprocess is needed to detect the edge from image data involving any noise, and a process of smoothing is usually applied to the data. However, the process of smoothing distorts the information with respect to its height, and so the E-transformation proposed by Moore and Parker is modified for retaining the height information in the data and identifying the edge of the image. The improved E-transformation is applied to rebuild an original shape from the height data in QFP measured with a laser.

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A new measuring method of a cylinder diameter by means of sound waves is described in this paper. The method is based on the phenomenon that the phases of sound waves scattered by a cylinder are delayed according to the diameter of the cylinder. Experiments were performed in the diameter range from 40 to 100 mm using 500- or 2500-Hz pure tone signal. Results showed that the phase. delay was linearly proportional to the cylinder diameter over a wide diameter range. The experimental results were compared with the theoretical results obtained by analyzing the problem of disturbance of plane waves by a cylinder. Agreement between the experimental and theoretical results was good. It was also found that reflections from walls and from a radiator increased the rate of change in phase delay with diameter. As a result, the utilization of reflections seems to be one method available for improvement in accuracy of this method.

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This paper describes the mechanical design of a microhead actuator for disk storage systems and its positioning control method. A new concept called "quasi collocation" is introduced to discuss the stability of positioning control systems for the structure. A simple actuator model is fabricated, and its dynamic characteristics are numerically and experimentally examined. On the basis of these results, a sensor and driving coils are positioned appropriately to achieve the quasi collocation. A trial servo system for this actuator experimentally confirms a wide control bandwidth beyond the mechanical resonance frequency.

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This paper deals with a path planning method for a structure configuration of Cellular Robotic System (CEBOT) which consists of a large number of autonomous robotic units called "cells." Since the CEBOT is one of the dynamically reconfigurable robotic systems, we propose a method for distributed decision making for the path planning, which employs a genetic algorithm. A genetic algorithm is a search algorithm based on the principle of natural selection and natural genetics. The decision making is improved according to the survival rule for the planning candidates. According to the concept of a distributed intelligent system, we propose a "distributed genetic algorithm, " in which the survival is selected in each local area. We present the simulation results for the planning in two cases as follows : ( 1 ) the case using a general genetic algorithm and ( 2 ) the case using a distributed genetic algorithm.

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Unknown force and unknown contact points for the case in which a planar two-fingered robot hand achieves a stable grasp on an unknown object are identified in this paper. It is shown that the unknown parameters of the grasping system ban be identified by detection of joint angles and torques while the object is manipulated slightly. Finally, it is illustrated by a numerical example that the algorithm of the grasp parameter identification is valid.

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In the previous paper, a three-dimensional finite-element method (FEM) model of a human middle ear was established. However, since the ossicles, which consist of the malleus, incus and stapes, were assumed to be one element, and the rotation axis of the ossicular chain was assumed to be a fixed straight line, it was impossible to reconstruct complicated vibration modes of the ossicular chain. Therefore, in this study, by taking account of the functions of muscles and ligaments of the ossicles and of the incudo-stapedial joint, an improved FEM model of the human middle ear was produced. Vibration patterns of the ossicles calculated from this FEM analysis were in good agreement with the experimental results using a video measuring system and stroboscope.

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The experimental results in a previous paper indicated that the angular extent of the oil film for porous journal bearings with no oil-feed hole, which is used as a small element of the feed port for nonporous bearings, is significantly smaller than half of the bearing circumference. In the present paper, the oil film extent under hydrodynamic lubrication conditions is theoretically analyzed on the basis of the following postulate : when the oil film extent reaches steady state, the inflow of oil into the bearing clearance through the porous matrix due to the oil-feed pressure must make up for the oil leakage from the clearance to both ends and to the porous matrix due to the hydrodynamic pressure generated in the oil film. The results show that the oil film region extends over a wide range for the higher dimensionless oil-feed pressure and smaller Sommerfeld number, which can be explained by the balance between the inflow and outflow across the oil film region. The data on the oil film extent are confirmed to be in agreement with the experimental results.

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When an object is pressed by a spring and fixed with friction force, microslippage often occurs because of an external force lower than the predictable value. This is because the object is pressed not only by the normal force but also by the tangential force. This paper presents a microslip model in which the obiect supported by spring forces in the normal and tangential directions is subjected to sinusoidal external force. The study shows both analytically and experimentally that larger tangential force produces larger microslip.

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Compositionally gradient coatings for thermal shock have been developed by a laser spraying method. They consist of titanium and titanium nitride. A pure titanium wire was melted by a high-energy-density carbon dioxide laser beam. An argon stream produced a fine spray of melted titanium particles which coated a mild steel substrate (60 x 60 x 4.5 mm) . The next layer was a mixture of titanium and titanium nitride which was formed by the mixed gas of argon and nitrogen. The last layer was coated with nitrogen only. The chemical components of each layer were graded through the coatings (about 1 mm thick). They were heated to 2000 K by a laser beam whose diameter and power density were about 42 mm and 290 W/cm², respectively, and cooled to room temperature in water. As a result of the repeating thermal shock test, it was found that these laser-sprayed coatings are excellent as thermal barrier coatings.

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The conventional method (three-moment balance method) used for calculating the power transmission efficiency of gear drives is well established. However, the authors have found an error in the conventional method. They present three universal methods which give the exact equations for the efficiency. These methods utilize the tangential forces between gear teeth, which are determined by considering the torque efficiency and the balance of the forces and moments. In most cases, the conventional method gives an approximate value which is a little higher than that obtained by the corresponding exact equation. The differential between the approximate and exact values becomes appreciably greater when differential motion is introduced to the gear drive.

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Antistatic plastic is one of the functional plastics which have been developed recently, but their characteristics when they are used as machine parts have not yet been elucidated. Consequently, various problems have occurred in their practical use. Therefore, in this study, gears were made of two kinds of antistatic plastics which were compounded by filling a conductible agent into matrixes of nylon (MC nylon) and polyacetal (copolymer), which are typical engineering plastics, and operation tests were conducted. The characteristics of the wear of teeth, the change of tooth profile and so on were examined, and the practicality of these plastics as gear materials was evaluated.

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In establishing an effective method for accurately estimating the frequency spectrum of noise power radiated from gears, a basic theory was proposed in previous papers using a circular plate with a solid shaft as a simple model of gear blanks. The basic theory was theoretically extended in another paper for the case in which the exciting force was applied in a spatial, three-dimensional direction, such as for helical gears. In this paper, the extended theory is applied to a circular plate which has a single helical tooth excited in its normal direction in order to verify that the extended theory is effective. The estimated sound power compared well with the value measured by the sound intensty method. Also, an interesting result is obtained; sound power radiated from a circular plate with a helical tooth is proportional to sin²β, whereβ is the helix angle. In other words, the axial exciting force has large influence on the sound power radiated due to the flexural vibration of the circular plate.

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The advantages of fiber-reinforced plastic (FRP) are that it has low density and high damping capacity. However, FRP had not yet been commonly used in machine tool structures because of its low Young's modulus, cheeping characteristics, and so on. The most probable use of FRP in machine tools seems to be in combination with a conventional material like steel in order to compensate for the low Young's modulus. In this paper, the damping characteristics of a composite structure beam, which is composed of a steel pipe and FRP, were investigated both theoretically and experimentally. The effects of the fiber direction, each wall thickness of the steel pipe and the FRP on the damping capacity were clarified. It has also been made clear that if the diameter of the composite structure is permitted to increase compared with that of the original steel structure, the damping capacity can be markedly increased under the condition of constant flexural rigidity.

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It is difficult to theoretically obtain three-dimensional flute configuration, as well as cutting edges of cutting tools such as endmills and drills, which are produced by disk or cup grinding wheels, because the configuration is an envelope generated by three-dimensional motion of the wheel. This paper deals with a theoretical analysis concerning this problem. For this purpose, a vector analysis which makes use of the rotational transformation tensor was adopted. The results of the simulation analysis carried out here yield a clue for improving the NC programming for tool grinding. The results of the analysis were also proved valid by some experiments.

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As a basic study to determine a simple method of improving the scoring resistance of a gear pair without using EP oils with marked chemical reactivity, the antiseizure capacities of mineral base oils on finely ground surfaces were examined by two-cylinder testing. The results were compared with those on roughly finished surfaces. The capacities significantly decrease with an increase in specific sliding even if the surfaces are finely finished. In the lower specific sliding range, the capacities are great without regard to the contact surface roughness and oil viscosity. Furthermore, in the lower range, the friction coefficient decreases with decreasing surface roughness and is independent of the oil viscosity. The thinner oil has a superior cooling effect to that of the thicker one. Finally on the basis of these results fundamental standpoints are proposed for the design of scoring resistance of a gear pair.

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The study deals with the development of ultraprecision milling machine, which allows to produce workpieces with sculptured surface. Until now, a variety of precise parts such as optical lens, laser reflective mirror, disc substrate and so on have been produced by ultraprecision turning lathes. However, the ultraprecision lathe can not cope with making sculptured surface, whose requirement is considered to increase. The ultraprecision milling machine developed in the study consists of an air spindle with a milling tool and a three-axis feed mechanism on which a workpiece is mounted. As a milling tool, a pseudo ball-endmill is designed by slightly offsetting a conventional diamond tool having a nose radius. It is found that the ultraprecision milling machine can produce workpieces with curved surface in surface roughness of 78 nm R_max.

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Roughness sensors which operate by means of optical stylus have advantages of noncontact measurement, relatively long working distance, high re solution and high accuracy. However, they also have some weak points. The range of measurement is insufficient and the allowable amount of local inclination of the surface is not large enough. It is established that the error due to the inclination can be compensated better by the null method than by the usual method. In the present paper, a new method to realize the null method by oscillating the objective lens and detecting the zero-crossing point of the periodically changing focal error signal is presented. The trial sensor has accuracy of about 20 nm and a measuring range of 20μm. By measurillg the time interval of zero-crossing points of focal error signal as an alternative to its voltage, the possible dynamic range of the sensor is expected to be enlarged by more than 80 dB.

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With the rapid development of mechanical industry, many kinds of thin metal plates have come to be used, but these plates are difficult to cut. One of the most important subjects in machine shops is to find an effective method for the cutting of thin metal plates. Low current air plasma arc cutting is one of the cutting methods which will hopefully meet such a requirement. However, there have been few studies hitherto which deal with low current air plasma arc cutting of thin metal plates. Under such a present-day situation, the application of low current air plasma arc cutting for thin metal plates was chosen as the subject of this study, that is, the effects of cutting conditions (stand-off height, cutting speed) on cut surface quality (kerf width, bevel angle, top edge condition, surface roughness, dross adherence, etc.) were examined. From this study, the relationship between cutting conditions and cut surface quality was clarified, and it was found that application of this method to the cutting of thin metal plates (SPCC and SUS 304) is effective.

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The need to grind the inner surface of a pipe has increased recently, but it is not satisfied by traditional grinding methods. On the other hand, magnetic fluid grinding with a float has been developed as a new method which has more flexible properties than traditional grinding methods. Magnetic fluid was applied to the grinding of a pipe inner surface. The maximum removal rate was 8.9 x 10^-12 m³/Nm. Optimum conditions existed in regard to revolution speed of pipe, shape of float, concentration and mean grain size of abrasive grain. The material of the abrasive grain and float influence the removal rate. Therefore, the pipe inner surface was ground effectively for practical usage by magnetic fluid grinding.

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A method of electromagnetic tube bulging by direct electrode contact is studied. The magnetic pressure is produced by a huge impactive electric current which passes through the electrode contact and the tube. The current is generated by the transient phenomenon of discharge on the condenser bank. An analysis of tube bulging is made using the finite-element method, and a formulation of the finite-element method based on the axisymmetrical membrane shell theory is developed. Impulsive magnetic pressure is assumed as an internal pressure load. The acceleration, velocity and displacement, and the (final profile and strain distribution are given. These agree approximately with experimental values.

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A flexible and incremental sheet metal bulging machine using a path-controlled spherical roller has been developed for the small-batch manufacture of nonsymmetrical shallow shells. The computer operations-controlled bulging machine performed a wide range of sheet metal shaping on complex shapes, for example, pyramidal shells, shells of the frustum of a pyramid, shallow pans and embossed panels. In order to predict the forming limit of incremental shaping, a new incremental bulging test by a ball punch was performed on an annealed aluminum sheet, and the experimental results showed that fracture occurred when the thickness strain reached n constant value. An approximate calculation method for the maximum bulging height of the shell was proposed, using this fracture limit and a geometrical deformation model. The predictions for the shell of the frustum of a quadrangular pyramid and the quadrangular pyramidal shell were in reasonably good agreement with experimental values for the annealed aluminum sheet.

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This paper describes a study of partial-load rattling noise of an oil-injected air screw compressor and its reduction method. Rotational vibrations of the male and female rotors were measured to detect the noise source. Relative rotational angle between the rotors greatly oscilated in a sharp sawtooth wave form of tooth-meshing frequency, corresponding to the rattling noise emission. The observations indicate that the rattling noise comes from the tooth separating vibration of the rotors due to decrease in the transmission torque. A rotor profile was so selected that the transmission torque never became negative even at a no-load operation, and this profile was applied to the compressor. As the result, neither rattling noise nor abnormal rotational vibrations were generated at partial load, as well as at full load.

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To materialize the actual designs in computer-aided design, we presented a method to determine the structural dimensions (design variables) in order to make all the requirements (objective functions) accomplish their respective objective values, using a newly introduced attainability which can describe heterogeneous objective functions in the same form. This paper presents another method which uses the attainability and simultaneous equations with several unknowns. The equations are composed of (k-1) th attainabilities, k_th sensitivity coefficients, and k_th revised values of the design variables which number as many as the attainabilities; k_th represents the k_th iterative calculation. The solutions of the equations give k_th revised variables and k_th revised attainabilities. The equations are composed and solved iteratively until all attainabilities become zero. In an automotive disk brake design, this method yielded satisfactory results in less iteration number than the former method did.

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In general, the electric circuits of automotive heated windows are designed on empirical knowledge and trial and error to satisfy the required power densities which substitute for the required window temperatures. In order to satisfy strict requirements and constraints in all cases, this paper presents a computer-aided design method of the electric circuits. The method devises an electric circuit model for the power density and a steady-state heat conduction model for the window temperature. The steady-state heat conduction of an element is calculated iteratively by the finite-difference method, considering heat transfers to six elements adjacent to the element. Width of filaments, thickness and width of bus bars, and kinds of paste (specific resistance) are revised iteratively until the required power density or the required window temperature is satisfied. The method was applied to a two-boxed passenger car and proved able to satisfy strict requirements.

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This paper describes a fuzzy directional control method for directional correction of a small-diameter tunnelling robot which constructs conduits of telecomunication cables. The directional control of a tunnelling robot conventionally depends on both the experience and intuition of the operator, and there have been no studies with regard to its automation. Therefore, in order to establish automatic control technology for a small-diameter tunnelling robot we proposed the fuzzy directional control method which can utilize both the expeience and knowledge of operators as a control rule. This fuzzy control uses a fuzzy rule set for [deviation, angular deviation] and [head angle (control input)]. We obtained an optimum fuzzy rule and optimum fuzzy set of values by using a dynamic simulator. Moreover, we obtained a fuzzy control method which can be applied to change the initial position of the robot. Simulation results clarified the validity of the proposed fuzzy control methods.

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