Self-excited oscillations are often observed in a circular disk when it is rotated in air. Analytical as well as experimental studies are conducted on these oscillations. As a preparatory study, free vibrations of the disk are discussed theoretically without taking into account the effect of air. Then, utilizing the results of this preparatory study, and taking into account the effect of air, the free vibrations of the disk are studied. It is shown that self-excited oscillations can occur over a certain rotating speed in the form of a backward traveling wave. Experiments confirm the theoretical analysis.

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Chaotic oscillations arising in nonlinear oscillations having the interaction between self-excited and parametric vibrations are studied. The equation of motion is described by the combined Mathieu-van der Pol's equation, and numerical integration is used to obtain phase plane portrait and Poincare maps for large time motions. Chaotic motions are investigated by Li-Yorke's theorem, the Liapunov exponent, the invariant probability distribution and Mel'nikov's method.

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Exact solutions of the free vibration in a single-degree-of-freedom system having an offset forced single-term cubic spring are established. By employing a certain bilinear transformation, the equation of motion is successfully converted into a regular Duffing equation whose exact solution already exists. The constants included in the transformation and Duffing's nonlinear spring are determined by solving simultaneous nonlinear algebraic equations along with the given initial displacement. The waveform of the solution is composed of even, as well as odd, order harmonics and is distorted so as to resemble a suspension bridge. The skeleton curve is also asymmetrical and the maximum and minimum amplitudes must be distinguished. The response reveals combined soft and hard spring characteristics and possesses a two-branched property within a certain frequency range. The exact solution is successfully applied to check the accuracy of an analytical approximate solution by the perturbation method as well as of the numerical integral by the Runge-Kutta-Gill scheme.

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An analytical method is presented for the bending vibration of a circular dise carrying concentrated masses, introducing a new mode of shape function to the Galerkin method. Deflection of the plate is expressed by a product of the mode shape function along radial direction and the circumferential periodic function. The mode shape function is assumed to be the sum of the product of the trigonometrical function and the finite power series. The coefficients of the power series are found to be satisfied by the boundary condition of the plate. Applying the Galerkin method, the number of sets of differential equation with second-order time functions are reduced. It is found that this method gives good accuracy to the natural frequencies within the small number of terms for unknown time functions

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Impact vibration of a beam with a spring is analyzed. From the condition of equilibrium of a force acting to the beam and a restoring force of the spring, an integral equation of the second kind of the Volterra type with respect to unknown restoring force is obtained. Considering the conditions of periodicity, a more complicated integral equation of Volterra type is obtained. Such integral equations are solved numerically, and relations between the maximum impact force and frequency of the exciting force and those between impact length and the frequency are shown. Also, bifurcation diagrams are shown.

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Vibrations of pipelines caused by internal pulsating flows are calculated by the transfer matrix method. The transfer matrices for static and dynamic transformation are constructed from the equations of a curved pipe element conveying fluid. Applying boundary conditions, equilibrium points, complex natural frequencies and mode shapes are calculated. Experiments were carried out for vibrations of simple pipelines caused by internal pulsating flows. The calculated natural frequencies of the pipeline systems show good agreement with those obtained by the experiments.

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Wear damage of heat transfer tubes should be avoided in order to improve the integrity of heat exchangers and steam generators. Tube wear is the result of tube/support impacting and rubbing motion caused by flow-induced tube vibrations. Evaluation of the relationship between the tube vibration and the tube-to-support interaction is a prerequisite for understanding tube wear. In this paper, tube-to-support interaction characteristics were investigated on a tube excited by flow turbulence. The results show that by using the magnitude of tube vibration under conditions free from tube/support contact and parameters representing tube setting condition in the tube support plate such as tube/support clearance and eccentricity, the characteristics of the interaction can be systematically evaluated.

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Based on the experimental data of vibrational response of two tandem circular cylinders, in two-phase cross flows, at the pitch-to-diameter ratios of 1.5 and 3.0 and for average bubble sizes from 3 to 4.0mm and 6 to 7.0mm, comprehensive investigations to the effects of pitch-to-diameter ratio and bubble size on the vibrational response characteristic cylinders were carried out. The following major results are found: (1) for both P/D=1.5 and 3.0, air bubbles caused the cylinder system to excite vibrationally when the flow velocity was smaller than that generating the lock-in state in the two-cylinder system: (2) in higher reduced velocity, air bubbles had suppression and excitation effects on the cylinder system which were dependent on the bubble size and P/D: and (3) in the lift direction of downstream cylinder's vibrathon, the large bubble size and P/D were more effective on the vibration response with respect to the reduction and excitation of vibration, but for thec upstream cylinder's vibration, the small bubble size and P/D were more influential.

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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 the aircraft or the space vehicle turns or responds to disturbances, the rotor may contact with the casing due to vibration caused by gyroscopic moment. In this paper, a dynamic analysis is performed on vibration of a mechanical system subjected to pitching motion of the frame. Flexibility and mass of bearing housings are taken into account and the axis of pitching motion 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. The dynamic response of the system in case of quick turn is also calculated.

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A new method has been developed to predict the dynamic response of a large spacecraft in acoustic environment during launching. In this study, emphasis was placed on the importance of the effects of the equipment masses attached to spacecraft panels. These effects are not taken into account in traditional methods, such as Statistical Energy Analysis (SEA). It is shown that the dependence on frequencies of equipment responses differs from that for responses of bare sections of the same panels. Emphasis was also placed on the effects of change of radiation efficiency of a panel due to equipment attached to the panel. When the number of equipment attached to a panel is large, the effect of radiation effiency change on the panel response is extremely important. The new method has been applied to predict the dynamic response of a model panel of Engineering Test Satellite-VI (ETS-VI). Agreement between predicted results and measurements is excellent.

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Directionally coupled vibration, referred to as "cross action" was analyzed to improve positioning accuracy in CD and CD-ROM optical pick-up systems having two-dimensional motion, i. e., autofocus and tracking directions. Cross action is defined as the secondary movement of the pick-up in the tracking direction when actuated to move in the autofocus direction. The main cause of cross action is found to be elastic resonance of the thin plate in the pick-up support. Assembly error is also found to amplify cross action. Optimum values for the support configuration were obtained by FEM and lumped mass vibration analyses.

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A new technique in time domain for the identification of nonlinear multi-degree-of-freedom vibratory systems has been presented. The main procedure of the technique is to divide the regions of displacements and/or Velocities into some small subdomains and express nonlinear terms by interpolating over these subdomains and determine system parameters as well as nonlinear terms based on the equations of motion. The technique is shown to be valid by numerical simulation. The comparison is then made among the proposed technique and other related main techniques, i. e. the technique using power series expansions, and the technique using Chebyshev orthogonal polyno mials.

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A method of estimating the sound pressure of structureborne sound included in noise radiated by an enclosure housing a machine that produces both noise and vibration is proposed. In this method, estimation is carried out without any change in the condition of installation of the machine using accelerations measured at the mounting points when the machine is in operation and frequency-response functions determined when the machine stops its operation. First, the theory of this method is briefly introduced; here it is assumed that the accelerations caused by the sound pressure of the noise emitted by the machine are negligible. Then this method is tested using an experimental setup in which the enclosure receives exciting forces of the machine at two connection points. It is shown that the estimated results agree well with the measured results. Finally, the limit of the validity of the above assumption is discussed.

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In order to suppress the structure-borne sound emitted from a vibrating plate, the vibration must be controlled. Unlike the convenional vibration control method which aims merely to eliminate the vibration, this paper rather uses the vibration to urge the cancellation mechanism of the sound. First, with a view to clarifying the generation mechanism of the structure-borne sound, the acoustic intensity is measured at each vibration mode. Then, from the distribution patterns of the acousic intensity, the cancellation mechanism of the sound due to the existence of the negative acoustic intensity is discussed, and the reduction of the acoustic power because of that is investigated. In addition, it is shown that the radiation patterns taken for granted so far do not hold good for some vibration modes. Moreover, from a viewpoint of a numerical simulation, the relationship between the radiation efficiency, the radiation power and the vibration level is discussed.

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In this paper, we consider an active dynamic vibration-absorbing control system which is subjected to disturbances generated by a linear dynamic system. There are two types of mechanisms. The first type had a complex mechanism which contains a spring and damper in addition to the mainmass, submass and actuator, and the other type has a simple mechanism without any auxiliary spring or damper. The simple mechanism has advantages of better performance for vibration control and less control energy than the complex one. The experiments demonstrate the effectiveness of the simple-type mechanism when it is used in an adaptive pole assignment control method containing an internal model principle which guarantees the complete vibration control of output displacement for all region of frequencies.

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A modal analysis is presented, by which the dynamics of time-varying frame structures under RD-control can be predicted with high accuracy, within short computation time and without causing the observation or control spillover at all. As numerical examples, deploying or rotatiog space structures and a moving arm are used. It is shown that the modal analysis presented here can be applied to the control of rigid-body motion of the space structures, which cannot be controlled by DVFB. for the rotating space structures and the moving arm, influencies of the reaction force and torque respectively due to the time-varying momentum and angular momentum of the rotating member beams on the controlled responses are studied.

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The PID controller with an analog circuit is ofen used in the active magnetic bearing system. Although this system is simple and nonexpensive, the vibration control for a flexible rotor is not sufficient. For the purpose of improving the modal damping of the mechanical system, the state feedback control scheme with dynamic observers is presented. The design of an estimator whose state elements consist of the modal coordinate and unbalanced force is based on a simplified reduced-order model of the mechanical system. This concept is applied to the experimental system of a flexible rotor suspended by an active magnetic bearing, and it is confirmed by measurements and numerical results that its capability to improve modal damping is superior to ordinary PID control.

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The balancing of a double cylindrical rotor which is a model of the super conducting generator is conducted by using finite element method and influence coefficient method. Two types of the model, the double bearings supported type and the flexible disc supported type are analyzed. Investigated is the influence on the balancing of the bearing rigidity, thickness of side plate which is connected to cylindrical rotors, and flexible disc. As a result, it is found that the optimum thichness of the side plate exists to minimize the residual vibrations for a given bearing rigidity, which is considerded to be very useful to design the super condacting generator.

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This paper deals with the vibration control method of a flexible beam. It is the purpose of this paper to present a new control method, the ABC method (Active Boundary Control method), which makes it possible not only to suppress all the vibration modes of the flexible beam, but also to realize the completely vibration-free state in the flexible beam. First, this paper presents the principle of the ABC method, and then the necessary conditions for the optimal ABC system are derived. According to this method, two more boundary conditions are introduced in addition to the conventional four boundary conditions. If the ABC method is applied to the driving point where the disturbance acts, it becomes possible to suppress all the vibration modes of the flexible beam. By applying the ABC method to the conventional boundary condition, it is also possible to realize the completely vibration-free state in the flexible beam.

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This paper deals with a problem of optimum structural design in which a shape for a beam-like structure is determined that minimizes the cost for vibration control under the condition of volume constancy. This is an approach to the simultaneous optimization of the structure and control function. The objective structure is modeled by the finite-element method, and the control law obeys the optimal regulator theory. Through the numerical examples, the effects of the initial state and weighting matrices on the result are discussed. Moreover, a two-step method for obtaining the optimum shape is proposed.

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In this paper, the tension of a very fine string revolving at a high speed is calculated numerically. The string formed around a rotating cylinder is reeled in by another cylinder. When the governing equation has no air resistance term, it is calculated analytically with an elliptic function. Here, the equation consists of the terms of tension, inertial force, Coriolis' force, centrifugal force and force of air resistance. It is calculated by using the Runge-Kutta method and as a result, the shape of the string, tension distribution and the limit revolution number, where the maximum of tension is equal to the tensile strength, are obtained.

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A high resolution and sheetlike form imaging tactile sensor with video signal output has been developed. The sensor has a 64×64 array of sensing elements on a flexible PC board with 1mm spatial resolution. Since the sensor outputs pressure distribution as a video signal, real time tactile image can be observed by using TV monitor. Moreover the same hardware and software of a vision system can be used for measured data handlings, tactile image processing and recording are very simple. As the sensor is made up of a sheet of pressure conductive rubber and stripe electrodes, there are undesiable current passes between sensing elements. Thus these undesiable current passes must be cut within a short scanning priod (500 ns for each element). We used a ground potential method and proved it useful under such a high speed scanning condition. The properties of pressure conductive rubber, including hysteresis and creap effects, are presented. A spatial filtering effect of an elastic cover for a tactile sensor is also analyzed. And it is proved this effect is very important. The final section shows measured data and image processing examples.

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This paper is concerned with the stability of viscoelastic Reut's columns having a damper. The effects of external and internal damping as well as the position of an installed damper on the flutter limit are investigated. It is shown that the damper attached to the column has a stabilizing effect on the flutter limit, and that the greatest stabilizing effect is brought about when the damper is attached to the column at about 20% distance from the free end. Experiment was carried out to verify the theoretical predictions. Reut's force was realized by an impinging air jet to a flat attachment covered with nonwoven fabric and mounted at the free end of the column.

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The law of mechanics shows that Euler's equation must be equivalent to Lagrange's equation concerning the rotational motion of a rotor. However, the research papers heretofore in issue are divided, as to equations of motion of a rotating shaft when the rotational speed varies, being accompanied by the terms due to the change of rotational speed. Since these terms consist of the second-order quantities of the shaft deformation, it cannot be demonstrated until the second-order quantities are perfectly expressed that the equations of motion are identical in essence independent of their method of derivation. The equations of motion in this paper hold an accuracy to the second-order, and explain the appearance of the second-order terms. The Lagrangian requires the deformation energy of the shaft to be expressed with an accuracy of the third order, which is derived by applying the theory of elasticity to bending and torsion.

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A screw conveyer is extensively used as transportation equipment for granular materials. Until now, there have been several reports investigating the characteristics of the screw conveyer, the influence of the rotational speed of the screw shaft, the size and the shape of a screw blade and the filling ratio of granules on the transport efficiency of the screw conveyer. However, a study of the transport mechanism of granules has rarely been reported. The transportation mechanism of granular materials inside the screw conveyer is very complicated. In this paper, the transporting state of granules inside the screw conveyer is investigated using two parameters: i. e., the transport quantity and the leakage quantity in the stationary state. First the relationship between the transport quantity and the leakage quantity is examined by measuring them practically. Next, on the basis of the relationship, the difference equation expressing the transporting state is derived, and the transient transporting state of granules is investigated by computer simulation.

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This paper presents a method to be used on correcting finite element models by refering their modal parameters to experimental modal data. The proposed method is based on both the sensitivity analysis and the least square method, and gives the physically realistic solution of design variables, in contrast with the methods based on pseudo inverse. Analytical simulations of a beam and a plate are presented to demonstrate the effectiveness of the proposed method in comparison to the pseudo inverse method in the aspect of structural reasonableness. In addition, the correction of a finite element model of an actual structure (bar) is shown by using experimentally obtained modal parameters.

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In the preceding papers, the authors proposed a new method of differential PWM for a hydraulic actuator operated by two 3-way solenoid valves. An arbitary pulse width of the pressure difference across both sides of the actuator piston was realized by adjusting the switching time of each valve. The actuator operated by differential PWM shows good linearity as a control element, achieving accurate positioning. This study, as the application, deals with a hydraulic servosystem composed of a 4-way spool valve and a load cylinder, where the spool valve is driven directly by the differential PWM actuator. The servosystem is designed by the optimal regulator method of the state variable model. The system performance is investigated by simulations and experiments. Consequently, it proves that the actuator, operated by differential PWM, plays the role of a linear control element, and the servosystem is well designed by the optimal regulator.

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Output torque/force of a hydraulic actuator is generally affected by its driving speed. This may cause deterioration of the control accuracy of the system in which the plant is controlled through the driving torque/force control of the actuator. This study proposes a positive angular velocity feedback for compensation of the effect of the driving Speed on the driving torque control of a rotary hydraulic actuator. The compensation scheme is experimentally applied to motion control of a one-link hydraulic robot which is controlled using the computed torque method. The experiments show that the compensation scheme is effective in isolating the driving torque of the actuator from its driving speed and slightly improves the tracking accuracy of the motion control.

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This paper discusses the regulator problem with the zero terminal state for a single-input linear time-invariant discrete-time system. First, for the general additive performance index, the fundamental structure of the accurate digital regulator which drives the state to zero within a finite time is obtained. This problem is divided into two sections; the new free terminal state problem in the former section, and the constant gain deadbeat control in the latter section. By using this fundamental structure, the new solution of the deadbeat LQ optimal control problem is obtained. Furthermore, the sufficiency of the optimal solution of the deadbeat LQ optimal control problem is shown by using the property of the linear-quadratic form.

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A kangaroo-type jumping and moving robot has been developed and investigated experimentally. The robot uses double pneumatic cylinders pivoted on both sides of its body for jumping. In order to jump, the initial position or attitude of the robot must be set, for which double DC servomotors installed on the body are utilized. The PID feedback control and sequential control are applied for setting the attitude by the motors and for the jumping motion by the cylinders, respectively. The conolusions derived from this experiment are (1) the pneumatic cylinder is very advantageous for jumping because it can provide quick higher jumps than other actuators, (2) the maximum jumping height of the robot in the vertical direction is over 500mm at the supplied air pressure of 6.0kgf/cm², and (3) the time interval between consecutive jumps and locomotion of the robot is less than 4 seonds.

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The authors have proposed a method of controlling a manipulator with passive joints which have no actuators. In this method, the coupling characteristics of manipulator dynamics are used, and no additional mechanisms are required. In this paper, a method to control the tip position of a manipulator with passive joints in an operational coordinate space is proposed. The equations of motion are described in terms of operational coordinates. The coordinates are separated into controlled coordinates and compensating coordinates. The number of the controlled coordinates is the same as the number of active joints. The accelerations of the controlled coordinates can be arbitrarily adjusted by using dynamic coupling of the manipulator. The effectiveness of the method is verified by experiments using a two-degree-of-freedom manipulator with a passive joint. The experiments show that the controlled coordinates of the position of the manipulator can be controlled precisely by use of the proposed method.

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In this paper, the position and force control of constrafined motion of robotic manipulators is discussed. First, issues related to decoupling position and force-controlled directions are discussed. The fundamentals of estimation of the contact force without using force or torque sensors are then presented, and a control scheme for position and force control of robotic manipulators without using force sensors is proposed. The extension of this scheme to redundant manipulators is also discussed. Finally, the proposed control scheme is implemented on a 3-DOF planar redundant manipulator, and the experimental results illustrate the validity of the control scheme.

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The relation between internal grasp forces and the stability of the three-dimensional grasp problem by a three-finger hand is studied. It is shown that internal grasp forces affect the angular stiffness of the grasp system. We propose a method stabilizing the grasp system by setting the fingertip stiffness in two directions which are at a right angle with fingertip internal forces, and show sufficient conditions and algorithm for the fingertip stiffness to stabilize the grasp system. Finally, several numerical examples whitch illustrate the algorithm proposed in this paper are presented.

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This paper deals with a new method of exciting vibration for the brachiation robot, which makes use of the swing of the pendulum due to gravity. A method using self-exciting vibrations and using the periodical change of spring constant in the system is proposed as a new method of exciting vibrations and the effect of exciting vibrations is shown with some simulations and experimental results. The experiment of exciting vibration is carried out respectively for the different methods of exciting vibrations and the effects of exciting vibrations are evaluated. Furthermore, the experiment is carried out for the brachiation robot grasping the shafts of a ladder in a horizontal situation. The brachiation robot can grasp. the first shaft of a ladder by swinging the body from the initial static condition. The mobility of the brachiation robot is demonstrated by these simulation and experiment results.

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This paper presents a visual recognition expert system for cooking robots. The "cooking robot" is considered to be a robot which chooses ingredients and tools and cooks automatically, once ordered what to cook. For the development of this kind of cooking robot in the near future, we believe the function of automatic recognition of the cooking state and the ingredient will become important. Regarding this point, this paper proposes a visual recognition system which can evaluate the doneness of meat and kinds of meat. The system recognizes the meat using image-processed data and pattern-matching data given by the neural network and synthesizes these data under the rules written in the expert system. Experimental results show that this system can distinguish the doneness of meat and the kind of meat excellently.

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In this paper, we propose a master cell for "Cellular Robotics (CEBOT)" as a director to decide CEBOT's activities. Since the CEBOT system can be considered to be one of the intelligent network systems, we determine the master cell of the system based on network energy estimation method (NEEM) between cells. Then, we describe both a method of "mastering", which implies the determination of a master cell, and a method of "mastering" by local energy-sensitive estimation (LESE) as a method of determining the master cell. LESE is based on local network energy only considered for cells adjacent to the cell. In this paper, we assume that the CEBOT structure is a binary tree structure because the CEBOT employs the hierarchical structure for control and communication. The master cell is difined as a window for users and as an information propagation source for the CEBOT. We can derive this network energy from both the transition probability matrix led by the communication transition probability and the stationary distribution vector. We also propose the connection load matrix to consider the channel capacity between cells. Simulation results of "mastering" both by NEEM and by LESE are shown in this paper.

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This paper deals with a small in-pipe mobile robot using the giant magnetostrictive alloy as actuators, which does not require any power supply codes. This cordless mobile robots can be controlled by the magnetic field supplied by the outer side. The mechanisms of the motions are based on the inch worm type of mobile mechanisms. In this paper, two mechanisms are shown: (1) the reversible motion and (2) the one-way motion mechnisms. The sizes of the robots are 21mm in diameter for the reversible motion and 6mm in diameter for the one way motion. The motion is controlled by the regulated motion of the outer electro-magnetic coil, so that the in-pipe mobile robot can follow the outer coil. This small mobile robot has many possible applications for the small pipe inspections, bio-medical fields and others.

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This study deals with task planning for disassembly/assembly of machine units by robots. This paper describes an algorithm for generating disassembly/assembly working, which is based on a data model of the assembly structure described by connective relations among parts. The algorithm can be divided into four stages. In the first stage, the disassembly sequence of machine units by robots is generated. In the second stage, the task is expanded to macro commands with task modules for disassembly. In the third stage, the macro command for assembly is changed by the macro command for disassembly. In the fourth stage, the macro command is expanded to the command in the work level. This algorithm is implemented as a knowledge-based system in Prolog. We have verified the effectiveness of this algorithm for experiments on disassembling/assembling machine units by robotic manipulators.

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The characteristics of the work space of a thumb-forefinger mechanism are discussed with the direction of turning stick and the zones of contacting finger surfaces. The finger hinge motions for turning a slim stick are determined under consideration of hinge angular speeds and hinge torque. This paper analyzs (1) the work spaces related to the contacting zone of finger surfaces (2) the work space evaluations on the speeds and the torques (3) the suitable direction of stick turning. Those analyses show that (i) the combination of thumb tip sphere and forefinger tip sphere has a work space which accommodates any direction of stick turning, (ii) other surface combinations suit a limited turning direction, (iii) the combination of thumb sphere and forefinger tip cylinder gives the most widely spread work space.

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This paper presents a study on the load bearing capacity of a copper alloy gear. The surface durability of the copper alloy roller and gear was investigated by carrying out running tests and compared with the results for the S45C normalized steel roller and gear. The bending fatigue strength of gears of copper alloy and S45C normalized steel was also investigated. The load bearing capacity of a copper alloy gear (mating gear:S45C) used in this paper was found to be higher by about 100% than that of a S45C normalized steel gear (mating gear:S45C). The copper alloy may be available as the material for a power-transmitting cylindrical gear.

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To know the tooth root stress of a bevel gear is very important for this intensity design. However, it is very difficult to obtain the tooth root stress of a bevel gear, because this shape is complicated. In the present paper, the stresses at the root of the fanshaped cantilever are calculated. Comparison of the calculated root stress with the experimental result by the fan-shaped cantilever-plate-testing apparatus confirmed the reliability of the present calculation method.

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When hypoid gears are used as high-reduction gears with a 90-degree shaft angle, the expected gear cannot be obtained by a calculation method for designing general hypoid gears. In our first report, we set up a fundamental formula regarding the design by a difference of the pinion shape. In the present report, by using the results, the calculation method with adjustability of the tooth bearing and degree of freedom for designing is investigated for the case in which the blanks of pinion and gear are of conical shape. As a result, it is clarified that a method for designing which accomplishes the above purpose is can be obtained if the gear spiral angle is freedom as a variable.

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In this paper, an exact method for calculating stress in closely coiled helical springs of arbitrary cross section is developed, and the shape optimal design method shown in the previous paper is scrutinized for adequacy. In order to obtain exactly the optimal shape of the wire cross section which minimizes the weigit of a helical spring, stress analysis should be exact and the convergence to the optimum should be foolproof. Therefore, the exact theory of stress analysis is first developed. In this new theory, stress is obtained by solving the functional derived from the state equation of the curved beam by means of FEM. Then the adequacy of the optimum design method shown in the pervious paper is confirmed through investigation of a bar problem.

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This paper presents a detailed discussion of the shape of the wire cross section of a helical spring that has the minimum weight under specified characteristics of a helical spring, especially where the coil curvature is large, Stress in the helical spring is calculated by the finite element method based on the stress function. The optimization problem is solved by the steepest descent mothod whose adequacy was confirmed in the previous paper. As a result, (1) it is assumed that many design points whose weights are almost equal to that of the global optimum exist around the global optimum point because stresses around the periphery of the wire cross section cannot be made uniform in the case of large coil curvature: (2) the converged solutions obtained from various initial shapes slightly differ in shape from one another, but are almost equal in weight; and (3) the converged solutions are not local minima, but are assumed to be located near the global minimum point in the design space.

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This paper presents an inverse analysis method to provied an efficient tool in designing flying head slider bearings for magnetic disk recording. The proposed calculation method is based on the static analysis of slider bearings and allows us to calculate the slider flying height, pitch and roll angle for a given load and loading point. Slider flying height and attitude angles are iteratively calculated from the time-independent Reynolds equation and three loading equations in translational, pitching and rolling directions. An iteration technique to ensure a convergent solution of the inverse problem and the convergent characteristics are discussed. The effects of radial position and skew angle on slider flying height and attitude angles are also presented for a 3.5-inch disk drive by using this technique.

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A numerical solution of elastohydrodynamic lubrication of line contact in combined rolling and normal squeeze motion is presented. The solution is obtained under the condition that the normal squeeze motion is instantly applied to the steady elastohydrodynamic contact between a rolling cylinder and a plane. The effect of surface waviness on the elastohydrodynamic line contact is studied as an operative example of elastohydrodynamic lubrication in combined rolling and normal squeeze motion. One of these calculated results is as follows. The initial change in the oil film thickness in a high-pressure area appears in the inlet region. Then the change in the oil film thickness moves toward the outlet region. The approach motion of the cylinder causes a temporary increase in the oil film thickness in a high-pressure area.

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In this paper, the seal mechanism of knife edge seals was explained and then a new type of a knife edge was developed. The following results were obtained. (1) The seal mechanism of knife edge seals was divided into the following three types according to the width of the flat land on the apex of the knife edge. (a) The penetration type, (b) the indentation type, and (c) the intermediate type. The PC/l-values of the compressive force for sealing were the lowest in the case of the (a) type. (2) The developed knife edge had the seal mechanism of the penetration type in the case of (a). The Pc-values of contact pressure for sealing were nearly equal to the Meyer hardness in the seal surface layer, regardless of both the surface roughness and the finishing of the seal face. In the case of the seal material of copper, carbon steel and stainless steel, the Pc/l-values were approximately 15-40, 45-110 and 80-190kN/m, respectively.

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This paper describes the design method and fabricated result of a hydrostatic air bearing spindle which has both high static stiffnesses and high damping ratios at resonance frequencies. The air bearing spindle designed by the proposed design method is composed of two thrust bearings of 110mm outer diameter and 55mm inner diameter and one radial bearing of 50mm length and 50mm diameter. The developed air bearing spindle has a high static stiffness of 500N/μm in the thrust direction, 110N/μm in the radial direction and 3.9×10⁵Nm/rad in the angular direction under the supply pressure of 0.49 MPa. Dynamic stiffnesses measured by the experimental modal analysis method are, respectively, found to be 1.8, 2.6 and 2.2 times the above-described static stiffnesses in each direction. These static and dynamic stiffnesses are found to be in a fairly good agreement with theoretical ones. Damping ratios are, respectively, 0.039, 0.035 and 0.055 in the thrust, radial and angular directions, which are roughly 50 percent larger than the theoretical ones.

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In metal cutting, it is a well-known fact that the value of Q/P, which is the ratio of the tangential force Q and the radial force P, is remarkably different in machining and grinding. In this paper, considering machining and grinding collectively, investigation on the effects of basic factors which produce such differences systematically was carried out by a simple model experiment. The results of the experiment made it cleat that compared to machining, in grinding, all values of the basic factors such as interference depth of cutting edge and workpiece, cutting speed, cutting edge condition, etc. are in the direction toward reducing the cutting force ratio. Moreover, the results of an overall grinding test showed that the force ratio in grinding is controlled by the product of the interference length and the maximum interference depth per cutting edge of the abrasive grain on the cutting surface of the grinding wheel.

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The bending strength of advanced ceramics as a construction material is not sufficient. One of the reasons for this is due to microcracks generated during the machining process. Firstly, this paper describes the effects of grinding conditions upon the bending strength of alumina ceramics. Secondly, the effects of vibration characteristics of the surface grinding machine upon the bending strength of ground ceramics is investigated. The bending strength of ceramics is measured by usint the 4-point bending method. The surface integrity and subsurface integrity were observed by using SEM micrographs. There are critical relations between the grinding process and the bending strength of alumina ceramics.

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