The crack propagation behavior in fretting fatigue was investigated with carbon steel S45C. Fretting fatigue tests were carried out under cyclic direct stresses of 100 and 140 MPa, and a contact pressure of p=80MPa for stress ratios of R=0.33, 0, -0.33 and -1. The crack closure phenomenon was monitored by the elastic unloading compliance method with a strain gage attached just beneath the crack front, and it was also observed on a TV monitor. The relationship between crack length a and crack propagation rate da/dN in fretting and unfretting fatigue was affected by stress amplitude σ_a and R. The crack closure phenomenon occurred markedly in fretting fatigue owing to the compressive force by the fretting pads. The effective stress intensity factor range ΔK_eff, calculated by using the measured crack opening ratio U, can represent the crack propagation behavior in fretting fatigue relatively well without the effect of R or σ_a.

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The present paper deals with a problem on the duration of impact between two bars. The two bars collide with each other longitudinally, one being plastically deformed and the other remaining elastic during the collision. In order to estimate the duration of contact between the two bars impacting each other, the variations of stress at the impact end are examined theoretically and experimentally. The theoretical predictions based on the strain-rate dependent theory for plastic wave propagation show that as the length of a specimen, the impact velocity and the magnitude of the dependence of strain-rate increase, the duration of contact increases regardless of the rising mode of the impact velocity and its rise time. The experimental verification was made by measuring the time variation of elastic-plastic stress at the impact end of a lead specimen in collision with an elastic stress bar made of carbon steel. The theoretical predictions almost agreed with the experimental observations.

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When applying the results of a model study to practical problems, it is convenient to know the relation of similarity in them. We experience an impact behavior as shown in a contact of cam and cam straddle, more space after punctuation arc spot welding, etc. This paper studies mechanical similarity in the collision between two round bars or a round bar and periphery of a circular disk, which are of various dimensions and material constants. It is important that the similarity of stress and the equation of motion are valid for the dimensions, material constants of the member, and the time. Supposing the dynamic similarity, we could investigate the response to the use of the material which is stable to the impact, instead of, for example, titanium of firing caused by heat storage resulting from rapid deformation, and valuable materials which need not be subjected to an unknown impact load.

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A solution is presented to a doubly mixed boundary-vale problem of the torsion of an elastic layer by an annular rigid punch attached to one plane face with the other face bonded to a rigid foundation with an annular hole. The problem is reduced to a solution of infinite systems of simultaneous equations by assuming that both the displacement on a plane face and the stress on the other face may be expressed as appropriate series. Numerical results are obtained showing the effect of a hole and thickness of the layer on the torsional deformation and the stress field, and comparisons are made with the results in the case of the absence of the hole.

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Effects of the contact condition at the first ridge on mechanical behaviors of threaded portions were analysed using an axi-symmetric FEM which is appropriate for the three-body elastic contact problem including the effects of friction on two contact surfaces between threads of bolt and nut, and between fastened plate and nut. The cross sectional shape of nut at the first ridge changes circumferentially due to the lead angle of thread, which causes non-symmetric mechanical behaviors concerning the ratio of flank loads and the stress concentration at the root of bolt. Four types of models were used to estimate these non-symmetric behaviors approximately. Each of them represents the cross section rotated one fourth revolution around axis. The analytical members are bolt, nut and fastened plate, and only the shape of nut is changed. The analysis is done by the axi-symmetric FEM without considering the effects of lead angle. The ratio of flank loads and the stress concentration at each cross section show some remarkable effects of the non-symmetric behaviors.

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This paper describes a method for the determination of fringe orders and directions of principal stresses in the whole region of a 2-dimensional photoelastic model by image processing. The fringes (isochromatics, isoclinics) are extracted as points where the first derivative of the density distribution is zero. The determination of fringe orders or directions of principal stresses between extracted fringes uses the values and pattern of extracted fringes. The results obtained can be displayed as a shaded image on the monitor TV, and be utilized effectively for stress analysis by the finite element method, etc.

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Three dimensional stress state in an internally-pressurized hollow cylinder made of fiber reinforced plastics is considered when its outer surface is restrained with a rigid hoop. Mathematical formulations are made within the framework of the transversely isotropic elasticity theory, and the use of two harmonic type stress functions and the method of Fourier transforms lead to a Cauchy-type singular integral equation of the first kind. Numerical calculations are carried out to show the effects of elastic anisotropy on the contact pressure and the bending stresses.

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The stagnation state of a flow induced by unsteady expansion waves is dependent on the strength of the expansion waves. Therefore, even if the initial condition in the supply tube of a Ludwieg tube is the same, the stagnation stage of the flow in the test section varies with Mach number of the flow in the supply tube. In the present paper, the starting process of a transonic Ludwieg tube with a quick-opening valve upstream of the test section was experimentally investigated over a range of the throat areas of the nozzle which is uniquely related to Mach number of the flow in the supply tube. Based on the results of the pressure measurements, wave diagrams showing the starting process were presented, and the effects of Mach number of the flow in the supply tube on the starting process were clarified with consideration of the flow rate in the plenum chamber.

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In case of zero-secondary flow of a supersonic air ejector with a throat in its mixing section, the flow in the ejector oscillates for a particular range of the stagnation pressure of the primary flow. In the present paper, the flow oscillation was experimentally investigated by optical observations and pressure measurements. It has been shown that an oscillation with frequency of about 100∼150 Hz is superimposed on as oscillation with frequency of about 3∼6 Hz, and that the former oscillation is caused by the jet from the primary nozzle oscillating vertically to the center line of the ejector. The mechanism of the flow oscillation has been clarified taking the behavior of the jet from the primary nozzle and the variation of pressure in the secondary stagnation chamber into consideration.

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This paper describes a developed annular cascade wind tunnel and newly advanced experimental techniques for investigating aerodynamic damping acting on an annular cascade in a transonic flow and at a high reduced frequency. For the study, a high speed mechanical drive system has been developed and Freon gas has been chosen as working fluid in the wind tunnel. The drive system can controlled-oscillate all the 16 blades composing an annular cascade in torsional mode at a constant amplitude and at a constant interblade phase angle up to a frequency of 500 Hz. This frequency corresponds to a reduced frequency of 1.2 (at M=1.4 and C=72mm). Three auxiliary apparatus also have been developed for aerodynamic damping measurement and flow visualization. With the experimental installations and the techniques, a lot of aerodynamic damping data have been collected on compressor and turbine cascades.

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Fluidic watering device has been developed, to which self-oscillaitng phenomena are applied, and which has a very simple structure. This device is named vortex chamber oscillation device. The jet is controlled only by a circular vortex chamber, and self-oscillation occurs due to a pressure difference between the left and right parts of the vortex chamber. By the momentum balance of main jet, the critical pressure difference to switch the jet left and right is calculated. By the difference between the masses of air flowing into the chamber through an air hole and air flowing out accompanying the jet, the time required for reaching the critical pressure is calculated, and the oscillation frequency is determined. This watering device gives appropriate size of water drops and uniform water distribution. This device was successfully used for the Shinkansen to melt snow on the track and the roofs of stations.

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An implicit finite-difference method to solve an incompressible fluid flow is proposed. In the method primitive variables (velocity and pressure of the fluid) are used, and an idea that the Navier-Stokes equations have a certain invariant in each iteration is introduced. As a numerical example, a two-dimensional transient Womersley flow is calculated. It is shown that the method has an accuracy of 0(Δt) (Δt : discretized time increment), and the accuracy of the present method is found to be satisfactory by comparison with the analytic and the existing methods.

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Measurements are made for the mean flow and turbulence properties of a three-dimensional wall jet issued from a circular nozzle adjacent to a wall into a turbulent boundary layer with or without an adverse pressure gradient, and into a quiescent fluid. The maximum velocity of the wall jet in the boundary layer decreases more slowly in the downstream direction than in the quiescent fluid, and these inverse values do not grow linearly with the axial distance. The half-widths in the normal and spanwise directions in relation to the wall, L_y and L_z, are considerably smaller in the wall jet injected into the boundary layer than in the one into the quiescent fluid. The variation of the maximum turbulent intensity is discussed in connection with those of two-dimensional wall jets with and without a wall flow. The patterns of the isopleths of the mean velocity and turbulent intensity are given.

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The axial velocity of a laminar, fully-developed pulsating flow in curved circular pipes has been measured by means of a laser doppler velocimeter in a wide range of various parameters, i. e. radius ratio of pipes R/a, mean Dean number D^^-, Womersley number α and flow rate ratio η. The experimental results agree well with the solutions of the numerical analysis. The instantaneous velocity measured is classified into a time-mean component and varying ones and the effects of parameters on them are discussed. Explanations are given for the complicated behavior of the curved pipe pulsating flows.

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Fully-developed turbulent flow in a rotating channel is simulated numerically by means of Large-eddy Simulation (LES). It is intended to supplement the difficulty of experiments of this type of flow with numerical analysis. LES is successfully applied to reasonably reproduce notable features of the effects of Coriolis force on the turbulent shear flow and its structure. Namely, the stabilization of the flow on the suction surface and the intensification of turbulence on the pressure surface by Coriolis force are confirmed. Also, modification of the time averaged flow due to the above effect is demonstrated in detail. It is also suggested that the subgrid-scale model of a very low intensity turbulence must be improved.

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Characteristics of the structure of a turbulent flow in a rotating channel have been investigated numerically using Large-eddy Simulation (LES). The authors previous paper reported successful prediction of the global effect of Coriolis force by simulation. In this paper, attention is focused on the behaviour of large scale eddies and the mechanism of production of turbulence under the action of Coriolis force is discussed. LES is confirmed to be useful to get experimentally. It is suggested that, in the Coriolis force field, the so-called sweep and ejection, which make a positive contribution to the production of Reynolds stress and turbulent energy, are intensified on the pressure side. Contrarily, on the stabilized side, the streak structure, which is closely associated with the production of turbulence, is observed to disappear.

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A practical mathematical model capable of predicting the dynamic strains in a finite length straight pipe subject to waterhammer has been investigated. The membrane shell theory, neglecting the radial inertial force, is employed and calculated numerically by the "two step Lax-Wendroff method" after having transformed the displacement equation of motion into equations of conservation for strain and particle velocity. An experimental investigation was carried out for two oil-filled straight pipes whose boundary conditions were open-fixed/closed-fixed and open-fixed/closed-free, and pressure fluctuations and axial and circumferential dynamic strains were measured. The experimental and analytical results are discussed in detail, and the proposed mathematical model and method of calculation are found to be sufficiently appropriate to evaluate the dynamic response of the pipe wall.

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It is, in general, a tedious and mistake-prone task for us to prepare a FORTRAN program which solves differential equations by means of the finite difference method. To avoid this procedure, the authors have developed a LISP program which generates the necessary FORTRAN code. The practical utility of the present LISP program is amply demonstrated by using this program for ordinary and partial differential equations. As an example, the authors solve the boundary layer equations which govern the flow on a rotating cone in a linearly retarded external axial stream. It is shown that as the effect of rotation grows, the flow ceases to separate from the wall, and then the axial, circumferential wall shear stresses and the local Nusselt number increase.

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The first-order solution to Oseen's equation is determined for liquid flow around a spherical gas-bubble at low Reynolds numbers under the assumption that the velocities and the stress are continuous at the interface between gas and liquid. This solution leads to new drag-coefficients of a spherical gas-bubble rising in quiescent liquid as Cd = 16 (1+ Re/8)/Re, where Re is Reynolds number related to the diameter of a spherical gas-bubble. The measurements of hydro-dynamic drags experienced by small gas-bubbles in quiescent liquid at the Reynolds number between 0.03 and 1.0 show good agreement with the new drag formula introduced in the present paper. The visualized streamlines around a spherical gas-bubble at the Reynolds numbers below 0.3 agree well with the streamlines predicted by the first-order solution to Oseen's equation.

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Critical condition for a small particle to collide with the wall is studied theoretically in an axially symmetrical stagnation point flow of an incompressible viscous fluid. In the phase plane the equation governing a particle trajectory has a singularity at the origin and the behavior of a particle motion near the wall is complex. The critical condition, under which a particle velocity is proportinal to the distance from the wall, is found by using the solution of particle trajectory expanded near the wall. It is governed by three parameters, that is, the Stokes number, the initial position and the initial velocity. On the contrary, in case of an ideal fluid, it is governed by two parameters, that is, the Stokes number and the initial velocity. The particle trajectory is obtained by matching a numerical solution far from the wall with an asymptotic solution near the wall in the phase plane. The results obtained here are also valid in case of the oblique stagnation point flow.

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The purpose of this study is to investigate the basic properties of a ferrofluid jet in a magnetic field. Using capillary nozzles which have various diameter, the behavior and the droplet formation of a water-based ferrofluid jet in a magnetic field perpendicular to the flow direction are experimentally examined. Then the factors greatly influencing the liquid column length and the droplet spacing of ferrofluid jets ejected from capillary nozzles are found by using dimensional analysis.

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The required NPSH (net positive suction head) of a pump with an inducer is determined by the suction and total head performances of the inducer and the suction performances of the pump. The authors have indicated that the influence of the performances mentioned above on the combined suction performance of the pump with an inducer depends on the pump discharge. The operating discharge range of the pump with an inducer is divided into three parts, in which the total head decrease occurs in the inducer and/or pump sections. In this report, the influence of the suction performances of the inducer and pump on the combined suction performance is investigated, and a method is proposed to predict the combined suction performance of a centrifugal pump with an inducer over the whole operating discharge range. The predicted results are compared with the results obtained experimentally.

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The effect of an air-separator to improve the low-flow-rate performance of an axial flow fan has been reported by present authors. This report describes the results of a flow measured within the flow passage of the fan equipped with an air-separator, in order to study the mechanism of the apparatus. The results suggest the importance of the effective removal of the lump of low-energy fluid near the fan casing, which is caused by, such as, leakage flow through tip clearance of blades. It has been confirmed that the air-separator is an excellent apparatus for this purpose.

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A design method of horizotal-axis wind turbines is presented, which is based on the lifting-line theory. †The design theory has two themes ; one is to obtain the circulation distribution of the minimum energy lost for a given output power, the other is to determine the expanded profiles and the pitch curve of a wind turbine blade for a given circulation distribution. The Goldstein function can be applied to the former theme. Kramer's diagram for two-bladed, three-bladed and four-bladed wind turbines are represented by means of the Goldstein function. Applying the present method, wind turbine blades are designed and their profiles are investigated. Furthermore, the performance of a two-bladed wind turbine is obtained by the experiments and compared with the numerical result calculated by the lifting-line theory considering viscous effects. It is concluded that the present design method is applicable to horizontal-axis turbines.

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Up to this time there have been many papers concerning theoretical and experimental investigations of the collection efficiencies of the axial flow types and of the returned flow types of cyclone dust collectors. However it is very difficult to estimate the collection efficiencies by a numerical analysis, since an exact grasp of the three dimensional turbulent rotational flow and of the behaviours of the fine solid particles on the centrifugal field in the cyclone dust collector can not be obtained. Therefore the authors made two kinds of normal (standard) cyclone dust collectors and five kinds of special forms (cone cyclones, sphere cyclones and a semi sphere and cone combined cyclone) of the returned flow types of the cyclone dust collectors. Then in order to compare the collection efficiencies of the normal cyclone dust collectors with those of the special forms of the cyclones, fine fly-ash particles were used as a test dust. In this paper the characteristics of the collection efficiencies of the above mentioned seven cyclone dust collectors which were related to the centrifugal effect, the feed dust concentration and the feed dust mass per unit time per energy dissipation of air flow are described in detail.

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This paper investigates how the local heat transfer coefficient is affected by geometric shape and the clearance "C", when turbulence promoters of various types (blockage ratio D/2H=0.22) are set in staggered arrangement in a rectangular duct in order to augment heat transfer from the wall. The distribution of local heat transfer coefficients depends on the clearance "C", which can be further differentiated by the presence or absence of the Karman vortex shedding. The degree of augmentation is also analysed, taking account of the pressure loss. It is found that the performance ratio η(the ratio of average heat transfer for the present system to that for a smooth duct under the condition of equivalent pumping power) is larger than unity for all types, when the range of clearance "C" is smaller than 3 mm.

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Three phase pressure drop in horizontal pipes was investigated for air-water-sand flow in 0.0416m I.D. pipe at atmospheric pressure and temperature and for hydrogen-solvent-pulverized coal flow in 0.0109m I.D. pipe at high pressure and temperature with use of a tube furnace in the coal liquefaction test plant. When the three phase flow was regarded as a two phase gas-slurry flow, the pressure drop in the three phase flow was flow was found to be reasonably well corre-coefficients for air-water-sand flow seem to be the same as those of simple slurry flow though some scatterings are observed.

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Magnesia ceramic is bonded to copper plate by a direct bonding method. This bonding method is the Refractory Method what has been discovered by the authors. There is a bonding region between the magnesia ceramic and the copper plate. Results of study concerning thermal resistance of the bonding region are described. The thermal resistance is measured by a method which has been invented by the authors. The bonding region is the most stable when the bonding is done at about 1120 °C bonding temperature. Bonding time hardly influences the value of the thermal resistance. A cuprous oxide (CuO) layer exists in the bonding region. Thickness of the CuO layer hardly affects bonding temperature and bonding time. Effective area of the bonding region for heat transfer is measured. The measuring method is based on an ultrasonic flaw detection. Effective thickness of the CuO layer is obtained from a viewpoint of heat transfer. It is found that the thermal resistance is mainly caused by the CuO layer in the bonding region and it mainly depends on the effective area of bonding.

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Following a study in which the area surrounding thin film thermocouples was assumed to be heat insulated as reported previously, the distribution of temperatures in thin film thermocouples embedded in combustion chamber walls of internal combustion engines which were in steady-state and unsteady-state temperature fields was studied, where the equations of different element methods, introduced in previous report, were expanded. Effects of the adiabatic layer and thermocouple body materials on the measured combustion chamber wall surface temperatures and heat fluxes were studied. As a result, it was indicated that thin film thermocouples capable of measuring instantaneous temperatures and heat fluxes on the combustion chamber wall with high accuracy, could be produced.

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A computer simulation of an N₂O downstream mixing gasdynamic laser is made using leaky stream tube approach. The numerical results show that the temperature rise due to mixing is significantly detrimental to the laser performance. In order to reduce the temperature rise, the area ratio of the N₂O-He nozzle should be made large. However, the supersonic solution in the mixed stream does not satisfy the second law of thermodynamics at very large area ratio. Therefore, within the range of the present investigation, the laser performance is optimized at an area ratio of 6. It is shown that a small signal gain coefficient of 2.25 m^-1 and the maximum available laser energy of 7.70 W/cm² attainable.

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This paper describes an experimental study on the ignition of unsteady hydrogen jets injected into compressed high temperature air behind reflected shock waves. Hydrogen gas was injected into the test section 8.5 -11 ms before incident shock wave were reflected from the end plate. Pressure measurements as well as the detection of light emission due to combustion of a hydrogen-air gas mixture were made with use of a photomultiplier and pressure gages. The results are : (1) The ignition delay time observed under the temperatures ranging 800 to 1600 K were from 0.5 to 15ms. (2) There exist ignition limits similar to the experiments with premixed gases. However the authors did not recognize clearly "explosion-peninsula". (3) The ignition delay time of unsteady hydrogen jets injected into the shock compressed air was longer than that of the hydrogen-air mixture, because finite duration is needed for mixing. (4) The low temperature hydrogen spurted into the high temperature air acts to decrease the temperature in the test section. As a result the ignition delay time for the unsteady hydrogen jet becomes longer.

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A laser doppler velocimeter was allied to a steady-flow test rig to analyze the transition of an intake swirl and a turbulence in a cylinder of a D.I. diesel engine. Three dimensional mean velocity and turbulence were measured with two kinds of intake ports that showed different engine performance. The formation process of the swirling flow in a cylinder was revealed by investigating the angular momentum flux around the intake valve and around the cylinder axis. The transition of the swirl and the turbulence along the cylinder axis showed a remarkable difference between these two ports. From the correlation with engine performance, it was found that the in-cylinder flow near the cylinder head (up to 0.6 ∼0.7 x bore) had more important effect on the engine performance than the swirling flow the swirling flow in the downstream region (1 ∼2 x bore apart from the cylinder head, swirl detectors are often placed).

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By means of gas sampling and gas chromatography, the process of mixture formation was observed in case that a volatile fuel was injected into the preheated air in a constant volume combustor. For the estimation of the density of an unburned mixture, it is necessary to measure both quantities of fuel and air in the mixture. In the ordinary method for that purpose, some exclusive gas chromatographs are used for organic and inorganic gas analyses, so that the same sample should be put into respective chromatographs. In order to diminish the accompanying troublesome procedures, the piping of columns in a gas chromatograph is so devised as to analyze simultaneously both components. Once a sample gas is put into this gas analyzer, both organic and inorganic components can be detected at the same time.

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The characters of oscillations induced in a nonlinear vibratory system whose natural frequencies are not in the ratios of prime integers and yet satisfy the condition of internal resonance, are discussed via a typical example. The example taken up here is a three-degree-of-freedom system whose linearized natural frequencies p_i (i=1, 2, 3; p₁ < p₂ < p₃) satisfy the condition p₁ + p₂ = p₃ of 2p₁ + p₂ = p₃, and which is subjected to harmonic excitation. The characters of oscillations induced in the system near primary as well as secondary resonance points are examined. For analysis the harmonic balance method is employed. The analysis reveals that near some of the resonance points the internal resonance occurs accompanied with three harmonics with their frequencies satisfying a certain relation. With three harmonics with their frequencies satisfying a certain relation. Also it is shown that an almost periodic motion can occur. The validity of the obtained results is confirmed by direct numerical integration.

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The subharmonic entrained vibrations of order 1/2 of a nonlinear retarded system with a soft spring type are investigated by making use of an averaging method, under the condition that both a periodic exciting force and a constant force are operative. The Routh-Hurwitz criterion provides the stability conditions of these steady oscillations. It is also revealed that almost periodic vibrations occur in the same frequency region in which the entrained vibrations appear. These two kinds of oscillations are studied numerically using mapping plots in the phase plane. The analytical results relatively agree with the numerical solutions and the results of an analog computer. In addition, it is shown that the subharmonic oscillations of order 1/2 can take place in the same system, even though there is only a periodic force as the stimulating force.

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Behaviors of a parametrically excited system with a self-excitation are investigated by analyzing a differential equation of van der Pol-Mathieu type. Beat phenomena are observed in the neighborhood of parametric resonance of order land their two kinds of approximate solutions are obtained. The comparison between them and a solution by Runge-Kutta-Gill method are performed and it is found that the existence of a solution approximated by two components is limited to a narrow region of frequencies. The character on the waveforms and frequency components is considered in detail.

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Using a pair of gears in mesh, an experiment is made on the forced torsional vibration of a two degrees of freedom system with a clearance between two rotating bodies. The experiment shows the existence of a phenomenon that two bodies collide with each other multi-times at one side of the clearance during a half cycle of the forced motion. It is suggested that this phenomenon does not occur in a single degree of freedom system but occurs in a system with at least two degrees of freedom. Effects of the dimension of the clearance and the average angular velocity on the strength of the impact force are investigated. A computer simulation is made. The results of the simulation show good qualitative agreements with those of the experiment.

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This paper deals with the self-excited vibration of a Mindlin circular plate subjected to distributed frictional forces as a function of relative slip velocity in tow regions on its outer circumference. The effect of the internal resonances is however not considered here. It is found form the averaging method that there exist two stable steady-state solutions of single mode with different spatial locations with respect to the tow frictional regions. In general the stable solutions become unstable as the distributed regions widen, but, on the other hand, the stable self-excited vibrations due to the distributed frictions occur anew. However, within a certain length of the distributed regions, the self-excited vibration characteristic has the same tendency as that due to concentrated frictional forces at two points, which was dealt with in the previous paper.

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The free vibration of rotating cylindrical shells is examined in reference to that of a thin rotating ring. The results of the experiment and the theoretical analysis for four kinds of boundary conditions (i, e., (A) both ends clamped; (B) simply supported without axial constraint; (C) simply supported with axial constraint; and (D) clamped at one end and free at the other end) are presented. It is found that the dependence of the frequencies upon the rotating speeds is insignificantly affected by the boundary conditions, and thus can be represented by the simple relation for a thin rotating ring, provided that the frequencies and rotating speeds are normalized by the natural frequencies of a non-rotating cylindrical shell.

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Large capacity magnetic disks require a head postioning accuracy in the order of a few micro-meters. This implies a technology to master the difficult problems of the disk-spindle assembly vibration. The following subjects are studied in this paper : (1) The gyroscopic effect on the natural frequency of the rotor-bearing system is experimentally made clear by exciting a rotating spindle. (2) The whirling force acting on the spindle system is dominantly caused by slight deformations on the ball bearing races. (3) It is shown numerically as well as experimentally, considering whirling direction, that the resonance causing a head positioning error results from a coincidence of rotor natural frequency and the ball bearing excitation frequency.

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We made experiments on the vibration s of a rotating shaft with a hollow rotor partially filled with liquid, and investigated especially the variation of resonance curves at the major critical speed and the effect of viscosity and specific gravity on the unstable vibration. As the result, the following are clarified. (a) A hysteresis phenomenon appeared in the resonance curve at the major critical speed. (b) The rotating speed where the resonance curve takes a maximum value becomes lower as the quantity of liquid increases. (c) The amplitude at the major critical speed changes variously depending on the volume of liquid, the initial bending of the shaft, and the unbalance of the rotor. (d) The width of the unstable region depends on the specific gravity of liquid but it is independent of the viscosity. (e) The growing rate of the unstable vibration decreases as the viscosity increases.

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Steady state deflection of cylindrical magnetic tape due to rotating head scanning is theoretically and experimentally investigated. The deflection is analyzed taking bending stress, tension, inertia and damping into consideration. The analysis shows that wavy deflection is caused both before and behind the head under some scanning conditions. The critical conditions and the effect of the scanning conditions on the wavelength and damping ratio are closely analyzed. An experiment is made on a transverse recording device and the results are compared with the theoretical results. As a consequense, in the wave length, the experimental results agree with the theoretical ones, where the damping force is calculated from the squeeze effect of an air film between the tape and the head rotor.

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This paper presents the hunting stability and curving performance of high speed rail vehicles. Considering non-linear creep force and flange contact, the lateral force of the leading wheel on outer rail is calculated in steady state curve negotiation. The critical speed of wheelset and the truck hunting are also calculated. The influences of the linkage which is so-called cross-anchor linkage, the linkage between wheelset and truck frame, and secondary suspensions which are composed of bolster anchors, anti-yaw damper and primary anti-yaw damper are examined. The results are compared with analytical solutions of an optimal design proposed by the authors for good stability and curving performance. Finally the design of truck suspension is discussed. By studying the difference among analytical vehicle models, it is proved that it is possible for analysis of hunting stability to use a truck model or a half body model. Moreover, the calculation results of hunting stability by using the half body model are compared to agree well with the test results of a vehicle conducted on roller rig in Railway Technical Research Institute of Japanese National Railways.

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This paper presents a new concept of a flexible and versatile shape reconfigurable control mechanism of a robot, called a versatile robotnoid (Vroid), which can be applied for plant maintenance work and other outdoor operational works, where the working environments are restricted due to mobile space and terrain. The Vroid I based on the multiple link-wheel mechanism has abilities of passing through rough terrains, passing over obstacles and going up and down stairways. Compare with the conventional wheel, crawler and legged locomotion types of the mobile mechanisms, the proposed Vroid I is considered superior with respect to flexibility and adaptability to working environments. Utilizing the redundance of joints in degrees of freedom, a method of the joint static control sequence is proposed to minimize the torques required to joint rotation under some constraints, which can easily be solved by the linear programming approach.

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Position and vibration control problems are dealt with for a gondola-rope system, in which the gondola is suspended by the rope from the above. Keeping in mind applications of this type of a suspended system for rescue works in case of fire in skyscrapers, it is necessary to control the position of the gondola toward targets and suppress the vibration of both the gondola and the rope. A vision system consisting of a TV camera is employed in this work in order to obtain the correct orientation toward the target automatically and search the targets in vibrational environments. Some useful techniques using the vision system are demonstrated for estimating relative positions between the gondola and the target at rest and even during vibration. And also a vibration control method is proposed which controls air jets in the on-off manner.

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In order to evaluate the severity of asperity interactions in rolling contact, the authors introduced a new parameter asperity interacting frequency Naf. Naf is defined by the number of contact points of higher hardness roller with different microgeometries which come into contact with any one point of mating roller of lower hardness. And the effects on rolling contact fatigue were examined using thermal refined or hardened rollers with different hardnesses. As the result, in a similar manner to the previous results obtained using normalized steel rollers, it is found that there exists a regular relation between the parameter Naf and the pitting life in pure rolling conditions. Furthermore, it is recognized that the occurrence of micro-pitting, which is apt to develop on the surface of a case-hardened steel roller, is decisively affected by the parameter Naf.

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In order to develop a simulation program for roll-finishing of involute helical gears in a crossed axes system, a new conception of a virtual lead correction was used in a calculation of the distributed loads on tooth flanks of skew gears. Using this conception, a theoretical calculation method of the tooth flank load distribution for spur gears could be applied to skew gears. Furthermore, in order to consider a free end effect on plastic deformation of work-tooth flank, indentation tests of two rotating rollers were carried out, and then an empirical equation represented this effect was obtained. The tooth forms calculated by this simulation program showed a fairly good qualitative agreement with the measured ones. Therefore, this program can help decide the optimum working conditions of roll-finishing.

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Theoretical solutions are obtained in terms of displacements and stresses for the case where a uniformly distributed load is applied in an arbitrary direction along the base line and also a uniformly distributed moment load is applied around the base line of a cylindrical shell without teeth. Furthermore, the maximum and worst shearing stress point is determined. The point is independent of the shape of the cylindrical shell.

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In the present paper, the root fillet stresses of welded spur gears of various dimensions and web arrangements are analysed by the three-dimensional finite element method (FEM). The effects of rim and web thicknesses, face width, web distance in double web gears and maldistribution of loads along face width on root stress distributions are investigated. Furthermore based on the results, the recommendable dimensions and web arrangement of welded gears (thin-rimmed spur gears) are indicated.

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In the 9th and 10th reports of this study, in order to investigate deformation and stress characteristics of a thin rim gear which are needed to determine the rim thickness, we calculated the deformation and stress values when concentrated and uniform distributed and uniform distributed loads act upon a thin plate shell in which one side is free and the other sides is built-in. In this report, we applied these calculations to actual gears, to propose a theoretical solution of the worst stress of tooth fillet when a uniform distributed load acts upon tip of the involute spur gears which have thin rim and center web. We examined its property by three-dimensional photo-elastic experiments.

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