The incremental transfer influence coefficient method is developed in order to analyze the periodic steady-state vibrations of a nonlinear system with a multi-degree-of-freedom system on a personal computer, combining the concepts of both the method of harmonic balance and the transfer influence coefficient method through the incremental method. The present method has some merits, that is, high computation speed, high numerical computational accuracy, applicability to the various types of nonlinearity and so on. For the stability problem, general and simplified methods are suggested in order to determine the stability of the periodic solutions from the behavior of the solutions of the corresponding variational equation, which is described as a multi-degree-of-freedom system with parametric excitations. The former is applicable to the variational equation in general and with high accuracy. The latter gives the sufficient condition for certain main unstable regions of the variational equation.

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High-speed rotors in jet engines or turbopumps used in space vehicles are mostly operated at a supercritical speed and their bearings and housings are usually supported elastically from the frame in order to reduce critical speeds. However, when an aircraft or a space vehicle turns or responds to disturbances, the rotor may be brought into contact with the casing due to the vibration caused by gyroscopic moment or centrifugal force. In this paper, a dynamic analysis of a rotor system that comprises flexible suspensions, a flexible shaft and a flexible disk is performed by a finite-element method. The rotor is excited by the frame's pitching motion, of which the axis is assumed to be distant from the center of mass of the rotor. The usefulness of modeling and the validity of the computational program are demonstrated by comparison with the experimental results obtained using a model rotor.

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This paper presents a study on the stability of a viscous liquid-filled rotor supported by a pair of magnetic bearings which are placed at both ends of the shaft connected to the rotor. The liquid is regarded as an incompressible one. The surface tension of the liquid and the gravitational acceleration are assumed to be negligible. In addition to the translational mode, the tilting mode is also taken into account here. The breakdown of the system consists of three parts : the motion of the liquid, the motion of the rotor and the control system of the magnetic bearings. The effects of various parameters on the stability of the rotor system, for example, the viscosity of the liquid, the liquid filling ratio, the position of the rotor, and the control parameters for magnetic bearings are studied theoretically.

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For high speed magnetically levitated (MAGLEV) vehicle systems significant attention must be given to the secondary suspension as it determines the ride comfort and has great influence on the vehicle stabilty. This paper analyzes theoretically and experimentally the performance of an active secondary suspension on the ride quality and running stability of repulsive MAGLEV vehicles. The suspension is equipped with a microcomputer controlled pneumatic actuator and it is governed by an optimal control approach. Two measures of performance have been analyzed: car body vertical acceleration (ride comfort) and truck-guideway gap variations (running stability). The experimental results show the performance improvement obtainable with an active secondary suspension and sufficiently agree with the theoretical simulation.

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This paper describes the vibration analysis of a three-element dynamic vibration absorber. The absorber is of one and one-half degrees of freedom and consists of an absorber mass, an absorber spring and an elastically connected damper. The effectiveness of the absorber in reducing the resonance peaks is greater than that of the two-element conventional absorber. The maximum force acting on the absorber spring is comparatively small for the effect of the elastically connected damper. When the main system has no damping, there are three effective fixed points on the amplitude curve of the main mass. Formulae for optimum tuning and damping are derived from a new thery of three fixed points. In the damped main system, the optimum values of the absorber are obtained through the numerical analysis using a Lagrange multiplier. The numerical results are given by the convenient empirical formulae.

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Welding is widely used for construction of structures. This paper deals with effects of welding on response characteristics and reliability of structures. First, the damping ratio and natural frequency of welded specimen are estimated by experiment. Second, by using obtained results, response characteristics of a mechanical model which is used to simulate a specimen subjected to stationary random excitations are examined. Third, the effect of welding on reliability is examined by estimation of first excursion probability. It is concluded that the effect of welding appears as an increase in the damping ratio and as a decrease in response and failure probability. It is also concluded that the effect of welding on natural frequency is very small. Finally, the applicability of obtained results to actual structures is examined by experiment. In this experiment, the damping ratio increases when welding is used.

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In this paper, we consider an active vibration control system based on a simple adaptive control (SAC) method when the system is subjected to bounded disturbances. The SAC method has advantages such that it requires little knowledge with respect to information about disturbances and plant-order when we construct a control system. However, the method was proposed only for tracking control problems. Hence, we first modified the usual SAC techniques to regulator control methods. Effectiveness of the proposed algorithm for the vibration control problems were confirmed by the experimental results obtained from the laboratory-scale experimental equipment of active vibration control. That is, the fundamental vibration suppression characteristics, such as robustness for the nonlinear friction and random disturbances, were attained by use of the modified SAC algorithm.

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For the study of the stability of nonlinear feedback systems, it is common to use a Lure-type Lyapunov function, and the most general approach by which to construct the Lyapunov function is the method based on the Popov criterion. In the case of product-type nonlinear feedback, however, the Lure-type Lyapunov function is not adapted well. Thus, the quadratic form of statevariables has been employed as a Lyapunov function. The Lyapunov method gives, generally, only the sufficient conditions for obtaining stability. Hence, it is important for system engineers to determine the Lyapunov function which guarantees a wider stability region. This paper presents Lyapunov functions for the stability analysis of dynamical systems with product-type nonlinear feedbacks. Stability criteria which introduce extended Lyapunov functions are given. The superiority of the function proposed is indicated by numerical examples.

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This paper is concerned with an optimum shape design for beams subjected to a moving load by using the fuzzy inference. The displacements of beams are minimized by the procedure which applies the fuzzy inference to the optimization algorithm. The results of optimum shape beams are obtained for various velocities of a moving load, and compared with those optimized by using the penalty function method.

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In the previous paper, a hump with elasticity was proposed, and numerical analysis was carried out on the hump in order to determine the influence of the elasticity on speed control for vehicles. In this paper, circular humps with elasticity are designed using a method of multiobjective optimum design in order to minimize the maximum value of the maximum accelerations of the drivers occurring while various vehicles cross a hump at a design speed for the hump and to minimize the maximum difference between the maximum accelerations of the drivers. The set of Pareto optimal solutions is obtained using the weighted Tchebycheff norm method. In addition, relations between the maximum acceleration of the driver and speed of the vehicle are analyzed numerically for each vehicle crossing the optimum elastic humps and an existing rigid hump.

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A method is developod that, by identifying the properties at local points, can improve an analytical model of a structure. Identificatin is accomplished by modifying mode shapes of the model based on measured eigenvalues and force equilibrium conditions within the analytical matrices that have deficiencies at the partial elements; precise mode shape measurement is not required. The procedure can handle large changes in the properties without the iteration of eigenvalues or sensitivity analysis. The singular value decomposition technique together with the vector weighting and additional rows appending technique, which stabilizes the solution, is utilized to derive the mode shape changes. Three cases of the method's application are examined by numerical simulation to demonstrate its performance.

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By our vehicle dynamics simulation program where a worn rail-wheel profile can be arbitrarily taken as input data, we investigated the mechanism that an arc wheel profile and decrease in primary longitudinal stiffness can reduce steady side thrust of a wheel when railway vehicles run on curves. In this paper, an outline of our program and the fact that the calculations are close to the data from running test in the field are described, and the following points are made clear: ( 1 ) In the case of small friction coefficient between the wheel and rail, the low stiffness is not so effective for reduction of the steady side thrust. The reason is that the differences of lateral creep force are not produced for different stiffness due to reaching saturation of the creep force when the friction coefficient is small. ( 2 ) The reduction of the steady side thrust of the outer wheel of 1st axle in the case of the arc profile is closely related to the motion of the 2nd axle.

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Organism are quite functional and the application of dynamics in organisms to the field of engineering is very instructive. To make an artificial propulsion mechanism by bending waves, a simulation study of a propulsion mechanism which imitated the bending motion of organisms in water was carried out. As the bending wave motion, flagellar motion, which depends on Stoke's law, was employed. In the simulation, the bending wave of the organism was changed into a construction of the multilink mechanism. This simulation model is defined as the "multilink model". In addition, the simulation model based on the approximate theory of the organism's propulsion is defined as the "approximate organism model". The thrust force ratio and the swimming speed ratio of the multilink model to the approximate organism model were calculated. The relationships between the two ratios and both the number of links and the ratio wavelength/amplitude were clarified.

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This paper proposes the use of an LQI (linear quadratic optimum control with integral action) theory instead of the conventional PID control for magnetic bearings. The principal advantages of a magnetic bearing are to provide friction-free and high-speed rotation without any physical contact. Many articles discuss conventional control theory for magnetic bearings. Modern control theory has demonstrated more effective vibration control for mechanical structures. The advent of improved microelectronics has led to increased control frequencies and improved stability. This paper discusses a controlling system design using the LQI theory for a magnetic bearing, and the experimental results demonstrate the advantages.

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This paper is concerned with the application of a two-degree-of-freedom (2DOF) digital controller to a hydraulic servo system. For suppression of a disturbance effect, the controller has an integral term and this causes instabilities by interacting with a saturation characteristic included in the actual hydraulic plant. To avoid the instabilities, a supplementary feedback loop is added to the 2DOF control system so as to suppress the input signal into the integral term under saturation conditions. A stability analysis is made for the system with that feedback loop and a nonlinear saturation element. Experiments are conducted under various conditions and from the results it has been clarified that the 2DOF digital hydraulic servo system has the prescribed desired input and disturbance response characteristics and that, even under saturation conditions, there occur no instabilities if the gain of the supplementary feedback loop is determined in the absolutely stable region obtained analytically.

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The influence of operational strategies on the optimal values of equipment capacities and utility maximum demands is investigated by using the optimal planning method for cogeneration systems proposed in the 1st report. As alternative operational strategies for prime movers, electric- or thermal-following modes and adopted, as well as the optimal one which minimizes the energy charge of input energy. As alternative ways of utilizing exhaust heat recovered from prime movers, a cascade method is adopted as well as the optimal one. A case study on a gas engine system for a hotel with a total floor area of 20 000 m² shows that the capacities of a gas engine-driven generator and other supplementary equipment depend significantly on the operational strategies. The adoption of electric-or thermal-following modes instead of the optimal one decreases the capacity of the gas engine-driven generator, while the adoption of a cascade method of utilizing exhaust heat increases it. The study also shows the importance of determining optimal equipment capacities in consideration of optimal operational strategies.

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The electrostatic force acting on the wire electrode is theoretically obtained by using the Maxwell equation, for the case that high electric voltage is applied between a wire and infinite plate electrodes in an electrostatic field. Then the static equation for the lateral deflection of the wire, in which the nonlinear electrostatic force with respect to the above deflection is considered, is derived in the case of the electrostatic field with corona discharge. The relationship between the static lateral deflection of the wire and the applied electric voltage is evaluated by solving the above equation numerically. Furthermore, the experiment showed that the theoretical results on the lateral deflection of the wire electrode were in qualitative agreement with the experimental ones in the case of corona discharge.

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This paper is a study on the response of rotating hard disks subjected to a half-sine acceleration in the axial or pitching direction. The solution is obtained by using the multimodal expansion approximation and applying the Galerkin method to the resulting equations. Numerical results are obtained by using the Newmark β method for 5.25", 3.5" and 2.5" hard disks spinning at 3 600 rpm. It is found that the disk holds its maximum displacement and acceleration when the input duration τ is about 1.5 times the natural half period of the (m, n)=(0, 0) mode. Here, m and n are the numbers of nodal circles and diameters, respectively. Results also show that the acceleration with 11 ms, which is nowadays widely used as a standard input on the shock test of the disk drive units, leads to only 60-70% of the maximum displacement and acceleration.

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In order to clarify the unstable vibration of a flexible disk coupled with a head and suspension system, the effects of constant friction force and other parameters of the head and suspension system are analyzed using a disk-head coupling model. In this model, it is assumed that the transverse and pitching motion of upper and lower head sliders interacts with a disk through transverse and pitching contact springs. The constant friction force destabilizes forward eigenmodes of the spinning disk, and this instability is largely suppressed by head mass and transverse suspension stiffness. However, it is found that this suppression effect remains small near the transverse natural frequency of the head and suspension system only when the upper and lower transverse contact spring stiffnesses are different. It is also found that the pitching vibration of the head amplifies the instability near the pitching natural frequency, while suppressing the instability in other frequency regions. Further, if the transverse and pitching natural frequencies of the head and suspension system coincide, strong instability is induced at this frequency.

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This paper is a study on the output of the force sensor which is used for the simulation analysis of the time-discrete digital force control of a miniature flexible robotic arm driven by piezoelectric bimorph cells. The output of the sensor installed on the tip of the arm modeled by ( a ) the product of the axial stiffness of the sensor with the relative displacement of the sensor to the object and by ( b ) the lateral force derived from the integration of the equation of motion of the arm. Model ( a ) is the classical, commonly used expression on the sensor output, while model ( b ) is the expression newly proposed in this analysis. It is found from the numerical analysis that model ( a ) presents unsatisfactory estimation while model ( b ) offers adequate results for the output of sensor which is used for a nimulation analysis for the time-discrete digital feedback control of the system.

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The authors developed a new type of mobile robot which had a spherical wheel, an arch-shaped body and motion controlling mechanisms installed inside the wheel. The robot can travel every direction and perform unique actions by virtue of its spherical wheel and motion controlling mechanisms. We call this spherical robot's controlling system IWBS (Inner Wheel Balancing System). The robot is inherently of a stable structure because of its large radius of the wheel and low positioned center of gravity. However, if a load is applied on the top of the body, the robot become unstable. Therefore, the robot is of a quasi-stabled structure. The compound gravity center control of the IWBS enabled this quasi-stabled robot to be controlled not only its postural stability but also every directional locomotion. This paper describes a development concept and mechanisms of the robot, computer simulation performed on the personal computer and experimental results of the robot fabricated concerning to the roll inclination control, running straight and along the S-shaped path control. By applying the learning control method proposed here, we have achieved the intelligent roll inclination control of the robot. It is expected that the robot can become one of the next generation robots for industrial as well as for personal use by developing its capabilities.

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This paper describes the analyses and experiments on postural stability control and ascent/descent on a slope of a spherically shaped monocycle-type robot. By applying the postural stability control methods proposed here, we achieved stability control of the robot not only on flat planes but also on rough ground even when unexpected disturbances were added. Also, a detection method of an unknown inclination angle of slopes was established using an analytical equation derived from the robot's mechanisms and an angle-compensation method. By virtue of the unknown angle detection method, the robot's ascent/descent of a slope with its arch-shaped body upright was attained. Furthermore, if we put a cup of water on the top of the robot's body, the robot can run without spilling any water from the cup. It is confirmed by the experiments that the all-direction steering-type robot developed in this study has great capability as well as versatility in home and personal use.

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This paper reports the principle, control methods and experimental results of steering control of a spherical-shaped, all direction steering-type mobile robot developed in this study. By applying spiral rotation method proposed here, we achieved the robot's dynamic rotational and steering control. Angle detection mechanisms for the robot's posture and measuring methods are also detailed. By virture of one-point contact at the ground and the aforementioned rotation principle, the robot can perform unique rotational actions. Furthermore, we confirmed that the postural stability control for the arched body shown in the previous papers contributed to speeding up the rotation of the robot. The experimental results show that the cooperative control of the arched body, the controlling arch and the wheel makes the robot travel in omni-directions and adds to the maneuverability of the robot. Therefore, it is expected that the robot has great capabilities not only in service applications but also as an amusement robot for personal and miscellaneous applications.

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Ultrasonic microscopy is highly regarded as a method for measuring the properties of materials by detecting the velocity of leaky surface acoustic waves. This velocity can be detected by measuring the output voltage of the transducer of an ultrasonic microscope as a function of the defocus of the acoustic lens [ V(z) curve]. The V(z) curve is obtained by the interference of ultrasonic waves generated by several reflections or refractions in the material. The complicated interference modes cause the misunderstanding of the results measured using an ultrasonic microscope. Therefore, well-analyzed characteristics of the acoustic lens are expected to avoid the misunderstanding. In this report, an optimum lens design method is proposed. Good acoustic characteristics of the lens are obtained by setting the aperture angle to the first zero point of the potential at the back focal plane of the lens.

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Ultrasonic characteristics of layered materials depend on their material properties and film thickness. Ultrasonic microscopes have been used for measurement of these material properties and the thickness of films. However, ultrasound reflects or refracts at the boundary of materials with different acoustic impedance. These ultrasonic signals interfere complicatedly, and this causes misunderstanding in analysis of the obtained data. For easy understanding of the data, it is useful to analyze basic models of layered materials. In this paper, we describe the ultrasonic characterization of gold film on glass. Change in the reflection coefficient and particle velocity with the incident angle of ultrasound are shown for several film thicknesses. Ultrasonic propagation behaviors on the delaminated film are also discussed. It is found that the propagation mode of ultrasound on the delaminated film differs from that of well-deposited film on glass.

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In the course of this study, the run-out characteristics of the externally pressurized gas journal bearings will be analyzed theoretically to establish the fundamental concept of precision design of the gas journal bearing, with special attention paid to the relation between the run-out of the rotor and the machining errors of the bearing. For the first step of the study, the modified divergence formulation (DF) scheme to calculate the exact solution of pressure distribution in the bearing clearance is introduced in this paper, in which the conventional DF scheme is improved to be applied to the case with point-sources of supply holes. As examples of the application of this scheme, the effects of machining errors such as out-of-roundness of the rotor to the bearing characteristics are discussed.

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The run-out characteristics of a rotor supported by an externally pressurized gas journal bearing are analyzed theoretically with special attention to the relation with the machining errors of the bearing system. Both the static and dynamic run-out characteristics are discussed. The form deviation of the rotor cross section (i. e., out-of-roundness) is attributed to the critical factor which may govern the run-out characteristics of the rotor. The effects of size deviation of the supply holes are also investigated. The obtained results may offer a fundamental concept of the precision design of the externally pressurized gas bearing with respect to the rotating accuracy of the rotor.

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In this report, the authors investigated theoretically and experimentally the inertia effects on the dynamic performance of externally pressurized gas-lubricated circular thrust bearings with a capillary restrictor in a turbulent regime. From the experiment, it is concluded that the effects of the inertia forces are considerable when the diameters of the capillary and the bearing clearance are large, and that the presented analysis yields good predictions of both the bearing stiffness and the damping coefficient.

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In this report, the effects of gas inertia forces in externally pressurized gas-lubricated thrust collar bearings with a slot restrictor are investigated theoretically and experimentally. From the experiment, it is concluded that the effects of the inertia forces are considerable when the slot clearance and the bearing clearance are large, and that the presented analysis yields good predictions of both the bearing stiffness and the damping coefficient.

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Thermocracking is one of the main failure modes in mechanical seals. In this paper, as the first step in establishing the mechanism of thermocracking, thermal shock tests are carried out by rubbing carbon graphite against alumina. It is shown that the states of cracks produced by thermal shock tests can be explained using thermal stresses calculated by FEM analysis. As a result, it is predicted that cracks in mechanical seals are caused by the action of high tensile circumferential thermal stress.

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There are power transmission shaft systems consisting of many belts and gears in automatic teller machines. In these systems, parts may be modeled by two-dimensional structures and may often be drawn by two-dimensional CAD systems. This paper presents an effective transmitted-torque analytical method for the power transmission shaft systems of drive-bill carrying machines. The main results are: (1) The driving-driven relationship of a power transmission system is introduced by a combination of motor, belts, pulleys, gears and shafts. (2) Using this relationship, a tree model is composed which defines the power transmission route. (3) Transmission torque and driving torque are calculated by adding the transmission torque of the lower layer in the tree model. The processing is carried out interactively in a two-dimensional CAD system.

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Interferometry using laser holography is applied for the purpose of measuring gear tooth flank form deviation of involute helical gear. The accuracy of the measurement by this method is comparable with that of the conventional measuring method using a contacting stylus. One problem with this method is that the curved tooth according to the helix angle of a helical gear interferes with the region of the flank to which the laser beam can be irradiated. The main reason for this interference is not due only to the existence of neighbouring tooth flank, but also to the fact that the incidence side of the objective tooth flank itself intercepts the beam irradiation upon the flank. To solve this problem, a method is proposed: As the first step, the objective tooth flank to be measured is divided into separate regions, and the contact free measuring is worked out. The measured values for the form deviation of tooth flank in each region are then concatenated into one on the whole plane of action, which results in a curved surface for the form deviation of the whole tooth flank of a helical gear.

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In the present study, the effect of lubricating oils with Mo additives on the tooth surface failure of heat-treated and case-hardened spur gears was investigated using a power-circulating-type gear-testing machine. The lubricating oils used in this experiment are of six kinds, namely a base oil (SAE 90) and five lubricating oils that are made by adding the extreme-pressure additives of S-P, MoS₂, MoDTC, S-P-MoS₂, and S-P-MoDTC to the base oil, respectively. Consequently, it was found that all of these extreme-pressure Mo additives increase the endurance limit of pitting fatigue failure, though only MoS₂ additive decreases the load-carrying capacity for scoring. MoDTC lubricating oil with no particles increases the antiscoring performance in comparison to MoS₂ oil with particles, but the pitting fatigue failure for MoDTC oil is larger than that for MoS₂ oil.

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Tooth flank form deviation of spur gears is measured by laser holographic interferometry. In order to get the diffracted ray from the objective tooth flank to be measured in definite directivity, a laser beam is irradiated with large incident angle to the surface which has a considerably rough surface finish. The conversion of the coordinates of the image figure of the objective surface, i. e. the gear tooth flank, on the CRT to the coordinate system of the gear is worked out by the fitting of contour form of simulated and observed images on the CRT. By using this method, image patterns of the interference fringe of some tooth flanks with various kinds of form deviation were measured. The algorithm of transformation from these fringe patterns to tooth flank form deviation by converting brightness of interference fringe images on the CRT to the amplitude of form deviation defined on the plane of action of the gear via phase difference of the light beam by a fringe scanning device is shown. The measured tooth flank form deviation is compared with the results of a conventional measuring method of tooth form using a contacting stylus.

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In order to develop hob material which decreases wear, the influence of composition, heat treatment, hardness, and transverse rupture strength (TRS) of a hob on flank wear and crater wear was investigated in this paper. Experiments were carried out with a simple fly tool. Powder metal high-speed steel (PM-HSS) is better than normal HSS in decreasing wear. Among the materials tested, PM-HSS containing high vanadium and high cobalt performed best. The influence of heat treatment on hob wear is different according to the composition of the materials. At a low quenching temperature and a high tempering temperature for PM-HSS containing high vanadium and high cobalt, hob wear decreases. Corner wear and crater wear decrease with increasing hardness, and with decreasing TRS. Materials having more than 900 H_v hardness and 3 000 N/mm² TRS are suitable for making hobs.

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This is to report the selection of number of flutes on multi-thread high speed steel hob for mass -production gears of automobiles etc., under the severe cutting conditions like more than 100 m/min cutting speed and 3-5 mm/rev. hob feed. The damage of hob is caused by many fields, like hob itself, gear blanks, hobbing machines, cutting conditons etc., And various type of damage can be found. The authors are hereupon to concentrate some typical damage (Corner wear, Extraordinary corner wear, Extraordinary side wear, Crater wear, Thermal crack, Chipping of cutting edge) that must be decreased in high speed hobbing with high efficiency.

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This report presents the development of a cutting machine for thick plate glass with "Elastic Working" which makes use of the progress of natural crack occurring at the fracture of brittle materials. The characteristics of this machine are as follows : ( 1 ) The system of the cutting machine is simple and plate glass can be cut to the thickness of 22mm along the desired scribe line without generating waste, noise, dust or heat, irrespective of the length. ( 2 ) The cut section is mirrorlike, and it is perpendicular to the face of the plate glass. ( 3 ) The energy required for cutting the plate glass is very small, and the cutting time is very short.

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The prediction of the cutting conditions leading to dynamic instability of a lathe requires knowlege of the vibratory properties of the workpiece or tool and the dynamic characteristics of the cutting process. This paper presents a method to predict the dynamic characteristics of the cutting process from the static cutting tests. Steady-state cutting tests are carried out and dynamic characteristic values as a function of cutting speed and feed rate are calculated. After some consideration of the dynamic cutting values and their components, it is revealed that the uncut surface slope variation with the vibratory workpiece influences the dynamic cutting process.

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The dynamic cutting process of the turning workpiece resisting regenerative chatter mainly depends on its inner and outer modulation. In this paper, the dynamic cutting characteristics of inner and outer modulation are estimated from dynamic cutting data obtained from experiments without special apparatus. The estimated characteristic values of dynamic cutting process are compared with the ones predicted from static cutting data by the authors' method in a previous paper. As a result of somewhat modifying that method, the predicted values correspond well to the estimated ones at a cutting speed of beyond 40 m/min.

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Functionally gradient materials 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 and a gas stream produced a fine spray of melted titanium particles which coated a mild steel substrate. The chemical compositions of the sprayed layer depended on the gas used. Different gases (argon, nitrogen and argon/nitrogen mixtures) produced coatings which comprised titanium, titanium nitride and mixtures of these components. The ratio of titanium nitride content to titanium in the sprayed layer was directly related to the argon/nitrogen ratio in the gas. Since the thermal expansion coefficients and the melting points of each layer are gradient through the coating, the laser-sprayed coating is expected to be applicable as a thermal shock absorbent or a thermal barrier coating.

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In order to investigate the effects of the shape of the top-jaw gripping surface on the chucking performance of a wedge-type power chuck, bending tests and gripping tests in the chuck-work system were performed. The investigation showed that the bending stiffness in the unloading process increases ( i ) when the diameter of the top-jaw gripping surface is a few millimeters smaller than the work diameter, ( ii ) when the gripping force is adjusted to the gripping area of the top jaw, or (iii) when the work is gripped at the base of the top jaw. Although the fluctuation of the bending stiffness in the loading process depends on the shape of the top-jaw gripping surface and the bending load direction to the top jaw, the absolute value significantly decreases with the gripping force. There is no effect of the shape of the top-jaw gripping surface on the gripping accuracy.

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A sequential-point method is often used for straightness measurement of machined parts. In a previous paper, we proposed the principles of the measuring method of roundness and flatness based on the sequential-three-point method. In this paper, we discuss the measuring error of the displacement along a circle, which forms the basis for roundness and flatness measurement. This paper shows the experimental results and computer simulation to investigate the theoretical results. In summary:1) A displacement error caused by output error of the sensor is estimated by computer simulation and 2) the error of the displacement measured along a circle is much smaller than the error of straightness measurement. Both errors are based on the sequential-three-point method.

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A computer-aided precision machining system which gives optimum tool design and cutting conditions for finishing process of end milling is developed. The system is composed of 3 modules. The input module evaluates the bending rigidity and the cutting performance of the end mill even if the capacity of the machine tool and the work materials are varied. A simulation module can analyze the instantaneous cutting force and the surface profile error produced by the machine-tool deflection. Also, the optimum design unit selects the optimum tool specification and the cutting conditions which can satisfy the expected accuracy and the removal rate. It is shown that the precision machining system can select the optimum cutting conditions that can realize the expected accuracy with maximum removal rate by means of existing machine tools and the end mill. It is also verified through the numerical experiment that the system has the faculty to design tool specifications for exclusive use in which the work material, finished work profiles and the machine tool are previously applied.

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Recently, the importance of system design in the field of mechanical engineering has been increasingly recognized. But suitable and useful methods for machine design are not yet established. An analytical method for the dynamic characteristics in the mechanical system, a method using linear graph theory, is proposed. In this paper, for the purpose of the practical use of this analytical method, a program which can analyze the dynamic characteristic automatically is developed. As an example, in the motion transmitting mechanism arranging the elements on the display of the computer, the system graph and the tableau equation are automatically produced, and the dynamic characteristics of the system are derived.

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This paper presents a high-functional 2-D CAD (Computer-Aided Design) system which is novel and quite different from conventional 2-D CAD (Computer-Aided Drafting) systems. This is the first report preceding the second one which mainly deals with the realized powerful functions called dimension-matching functions. In this paper, we first discuss the insufficiency of the present 2-D CAD systems. Based on the discussion, we then propose a structural model of a mechanical drawing, i. e., both attribute and relation representation models, for representing the highly organized information which mechanical drawings have. Finally, We show a method of automatically generating a relation representation model using knowledge processing.

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A surgical operation is carried out on the grounds of sufficient professional knowledge. If an expert system for the plan and simulation of a surgical operation is constructed, it is possible to support the surgeon and the nurse who hands over the surgical instruments. This study deals with knowledge acquisition for creating an expert system of a surgial operation. The structure of a surgical operation is elucidated by using 'the page model' which is the method of knowledge representation, and the rules are acquired. The motion unit is constructed from these rules. Further, as these units are connected in an inference engine page, the complicated sequence of a surgical operation can be formulated and represented.

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This paper proposes a design method using H^∞ control theory concerning an active dynamic vibration absorber for multi-degree-of-freedom systems. In particular, the weighting functions of H^∞ control are discussed as to which one is better. We finally propose the best weighting functions for vibration control, robust stability and stroke limits of the dynamic vibration absorber in two cases, namely, a hybrid dynamic vibration absorber and an active dynamic vibration absorber. The control object is a tower structure with four degrees of freedom, two vibration modes in the lower frequency domain as the reduced order model should be controlled, and another two higher modes as the residual model should be uncontrolled on the condition of robust stability without spillover. We have confirmed the strong robustness concerning parameter variations of the spring constant and the damping constant in the case of a hybrid dynamic vibration absorber. Also, it has been made clear that an active dynamic vibration absorber designed by H^∞ control theory is effective against seismic disturbances such as the E] Centro earthquake.

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A design of a nonlinear controller for overhead traveling cranes with winding mechanism is shown. The nonlinearity is due to the change in the loop length while a load is wound up and down, and is a cause of undesired load swing in the crane operation. The proposed nonlinear controller compensates it and reduces the swing considerably. A local stability of the closed system with the controller is proven. Experimental results illustrate the effectiveness of the controller.

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The limiting drawing ratio of the optimum blank is considered theoretically and experimentally, with particular reference to the improvement of the deep drawability of sheet metal for nonaxisymmetric cups with a flat-headed punch. The authors' calculation methods for the optimum blank and the limiting drawing ratio have been applied to the square, the false elliptical, the rectangular and the rhombic cups, and the prediction was obtained in terms of the relationship between the optimum blank shape and the drawing ratio. The forming limit diagrams of those drawing cups were conceived theoretically, taking account of the die radius, Coulomb friction and the blank holder force. The calculated results agreed well with experimental results from deep drawing tests on a brass sheet, and it was found that the limiting drawing ratio and the maximum drawing depth of the cups drawn from theoretical optimum blank shapes were much larger than commendable values based on practical experience.

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