In order to derive theoretically the fatigue life distributions of metals and alloys, it is assumed that a propagative fatigue crack is initiated at the region on specimen surface where the slips occur in two or more mutually adjoined grains, and that the orientation of a grains distributed uniformly in every directions. Then, the linear models for the configuration of grains in the surface layer are combined with these assumptions for the simplicity of formulation. Theoretical results obtained here are in good agreement with the trends of the experimental results on the distribution of fatigue lives in low stress levels near the fatigue limit. Especially, the trend of the probability of failure being saturated at a finite level and the stress dependency of this trend are well explained by the theory established in this study.

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The problems of the interference of notches and loaded ends which must be considered especially in the material test are discussed quantitatively. For this purpose, in the 1st report, the cases of a strip with two semicircular notches under several tensile load conditions along its ends, with its axial length varied, are taken up. For the analysis, the indirect boundary integral method together with the frictitious boundary method is used. Furthermore, by the same method of solution, the problems of stress concentration due to U-shaped notch are treated.

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This paper deals with the axially symmetric torsion of a hollow cylinder with an internal crack. It is assumed that the curved surfaces are free from stresses. The boundary value problem is shown to be equivalent to a problem of solving a pair of dual series equations. This dual series equations are reduced to an infinite system of simultaneous equations. Numerical results are presented for stress, displacement and stress intensity factors.

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A theoretical method is presented for the bending problems of perforated plates within the framework of the Poisson-Kirchhoff theory of thin plates. The method is illustrated by giving the solution for an infinite plate with a doubly periodic set of circular holes having a square or triangular pattern under unequal uniform bending moments about the axes of symmetry. Numerical results are given for the distributions of the bending moments around the holes and stress concentration factors over the entire range of pitch to diameter ratios of general interest. The results show the power and flexibility of the technique. The solution obtained here can be used, just as it is, for a plate with holes of arbitrary shape and array. Also the extension of the method to a plate under a class of loads other than uniform bending, e.g. twisting moment or transverse shearing force acting on the edges of the plate is quite straightforward.

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By method of singularities, the theoretical treatments of two-dimensional centrifugal impeller blades vibrating harmonically with the arbitrary frequencies and the phases are described for the forces and the moments under the assumptions of an incompressible, inviscid, nonstalled flow. Some computed results on the case of radial impeller blades are presented. The results show that the aerodynamic damping forces and moments about rotational axis vary significantly near the integer values of the ratio of vibrating frequency to rotational speed, so that the instability of single degree of freedom becomes possible at the frequencies depending upon the vibrating phase angle.

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A reservoir-orifice with variable opening area has been developed for extending the useful steady flow duration of a Ludwieg tube. The orifice which separates the reservoir from the supply tube is made such that its opening area increases properly from a certain initial to a final value during the running. The unsteady expansion waves generated by the opening of a valve or a diaphragm propagate upstream in the supply tube and interact with this orifice. The interaction process is investigated, and the conditions when the reflected waves become compression, Mach or expansion waves are clarified. When the orifice reflects only Mach waves, i.e., complete elimination of the reflected waves can be achieved, the extended running time by the present method is much longer than that of the conventional Ludwieg tubes.

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This paper studies the propagation characteristics of pressure wave through a gas-liquid plug-train system which is one of the simplest flow regimes for two-phase flow. A relaxed pressure wave occurs owing to both liquid inertia and gaseous compressibility and propagates at a slower speed in this system than in a gas. The experimental results for an air-water plug-train system at rest in a pipe agree qualitatively with the analytical results for a coupled mass-spring model. The system shows a peculiar dispersion property and behaves symmetrically and concavely with respect to 0.5 in void fraction. The propagation velocity of pressure wave approaches the maximum, which is equivalent to that of pressure wave in a homogeneous two-phase mixture, as the plug length decreases.

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The effect of a transverse magnetic field on a steady flow of liquid metals in curved rectangular channels is studied theoretically in this paper. A solution is obtained using the boundary layer approximation. The results for the resistance coefficient agree well with the experimental results over wide ranges of Hartmann numbers, Dean numbers and aspect ratios. Besides it is made clear that the suppression effect on the secondary flow by the Lorentz force gets larger with an increasing Hartmann number, so that the value of the resistance coefficient for a flow in a curved channel coincides with that in a straight channel even at high Dean number regime.

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Flow patterns of a supersonic air flow and the related noise characteristics are studied by experiment for simplified geometries of the valve. The valve consists of a conical plug and a plane seat, and high pressure air is discharged through it into atmosphere. The pressure ratio is up to thirty. Various types of the flow patterns are shown by shlieren pictures. It is found that, as the pressure ratio increases, the flow along the plug surface is abruptly separated to attach to the seat, and that, at the same time, the noise is reduced by more than 10 dB(O.A.). The pressure ratio where the attached-to-plug flow is recovered is lower than the ratio where the attached-to-seat flow occurs. This change of pattern, which may cause a significant variation of force on the valve trim, is closely related to shock-boundary layer interaction.

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An analysis is carried out on the radiative transfer in a paint-type coating layer of absorbing and anisotropically scattering medium with two different boundaries of air-coating and coating-substrate. Mie scattering equations are used to evaluate the scattering and the absorption coefficients of the spherical particles of the pigment. A numerical approach to the solution of the transfer equation, using Gaussian quadrature formula and Gaussian elimination procedure, is presented. The effects of the optical properties of the pigment (TiO₂, Fe₂O₃ and carbon), the pigment volume concentration, the absorption by the vehicle and the reflection characteristics of the substrate (specular or diffuse) on the bidirectional and hemispherical reflectances are examined. The wavelength dependence of the results is examined also in the range from 0.35 to 20 μm.

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Further improvements in thermal efficiency of steam and nuclear power plants are an important problem in the present energy crisis. This report presents the performance characteristics of two fundamental condensation cycles employing carbon dioxide as a working medium. The effects of cycle parameters on thermal efficiency in non-reheat and reheat condensation cycles and values of optimum reheat pressures are discussed. Furthermore, losses in each component in different Co₂ cycles by utilizing the exergy concept based on the second law of thermodynamics were analyzed and the effects of regenerating on irreversible losses were discussed. As the result, it was shown that at turbine inlet pressure of about 250 ata and turbine inlet temperatures higher than 650°C CO₂ condensation cycles in double- or triple-reheating give a better performance than conventional steam power-plant cycles.

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A theoretical analysis is presented on a transient process through which non-equilibrium state occurring in saturated liquid-vapor system changes to stable equilibrium state. In this analysis, energy flux and mass flux between the liquid phase and the vapor are expressed by the phenomenological transport equations. The transfer functions between the change of the volume or mass in this system and the resulting change of the pressure or temperature of liquid and vapor are obtained, when these changes are fairly small. The natures of the two-phase transient phenomenon, especially the change of pressure and temperature, were discussed by using the results of numerical calculations in the case of carbon dioxide and water, whose material properties are different from each other.

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Experiments were performed on the response of a flame stabilized in the wake of a circular cylinder to sudden acceleration or deceleration of a free stream with the use of a shock tube with two diaphragms, which served as a short-duration wind tunnel and a generator of plane waves of regulated strength. Interesting features in the behavior of a wake flame subjected to acceleration were found, viz. the formation of a bottle neck contraction, its convection downstream, its growth with time and the splitting of the burnt-gas region, followed, at lower accelerations, by the development of a new flame and pressure oscillation. The extinction of combustion occurred at higher accelerations. On the other hand, a partial expansion of the burnt-gas region was found behind the flame holder when subjected to deceleration, but pressure oscillation and flash back were not observed.

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The least-squares method which uses influence coefficients was applied to a multispan, multibearing rotor system (10 bearings, 5 spans), and its effect was investigated. In this paper, the above balancing method was applied in the case where unbalance is distributed in one of the rotors in a multispan rotor system. The experimental results were as follows; (i) Simultaneous multiplane, -multispeed, -2 directional balancing yielded excellent results. (ii) When both horizontal and vertical vibrations are considered in balancing test, accurate balancing is to be expected.

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In a previous paper (Part I), the mechanism of wheel vibration was investigated theoretically and experimentally. In this paper, the effect of the rate of rotation and the load on the vibration, and the characteristics of sound radiation are discussed. The vibration and the noise levels increase with the rate of rotation. The load, however, has no significant effect on them. The frequency distributions of both are affected by the rate of rotation and the load; i.e. under a high rotation with a low load, the frequency distribution approaches that of a free disk. Coefficient of sound radiation (the sound power divided by the mechanical power) is introduced to investigate the characteristics of sound radiation. The coefficient has a large value at low order natural frequencies and a peak at a frequency which is higher than the coincidence frequency. As the diameter of a wheel increases, the peak frequency approaches the coincidence frequency and the peak value increases.

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High speed rotating machines, such as the centrifugal machine, may have deviations of mass, stiffness and damping coefficient in manufacturing process, and are also exposed to the danger of earthquake. In the design of a rotor system, these factors should be accounted for from a view point of reliability. This paper deals with this problem specifically, when the statistical properties of errors of a rotor system and those of an earthquake (i. e. its period, magnitude and statistical character of wave) are known, the statistical properties of the rotor vibration are obtained, and a period of the first collision with the guard of the rotor system is calculated in a statistical sense. It is concluded that the statistical property of the seismic wave has more influence on the reliability than that of the damping coefficient in the rotor system. If the statistical relation between the magnitude and interval of an earthquake is known, the period of the first collision with the guard can be obtained.

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This study deals with the manipulator control problem from the dynamical standpoint where the time factor plays an important role. It includes a coordinate transformation of the position and posture and the force and moment, a control of the coordinative motion, and a visual feedback control. In the first report, the coordinate transformation necessary to control the coordinative motion of the hand of a manipulator has been analyzed. As the result, it is shown that there are several singular points determined by the arm mechanism. At these singular points, the kind of the configuration of the arm for the same position and posture of the hand changes and the number of degrees of freedom of the hand decreases. Utilizing these results, a method of calculation of the global coordinative motion is proposed. This method eliminates the difficulties which may arise at the singular points and enables a change of the kind of the configuration.

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In the second report, a computer control system of the coordinative motion of the mechanical arm is described. This control system is a real time system which consists of a servo system to control the motion of the arm, tactile and visual information processing systems and some other subsystems. The servo system is a software servo system, of which the controlling unit is constructed of a computer software. In this controlling unit, a mathematical model of the arm and its driving unit is programmed. Making use of this mathematical model, the motion, force and moment of the hand and the stiffness of the servo at the hand can be controlled in various coordinate systems properly designated in the work space of the arm.

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In the third report, a visual information processing system and visual feedback control of a hand are described. By this visual information processing system, it is possible to track moving objects and to measure their positions and velocities. As mentioned in the second report, this processing system is stored and run in a different computer from the one which controls the motion of the arm. The visual feedback control of the hand is performed by making use of these parallel processing systems. As a work example of these systems, a task of catching a rolling ball by the hand was chosen and carried out. In this visual feedback task, anticipating the catching position and time of the rolling ball from its measured position and velocity, the hand moves to this catching position by this time and catches it.

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The generating mechanism of frictional noise in dry friction is experimentally and theoretically studied, when a contact rod clamped at one end is pressed in the radial direction on a rotating disk. The results are obtained as follows: (1) Frictional noise is classified into two categories, rubbing noise and squeal noise. (2) When the coefficient of friction between the rod and the disk is small, the vibrating energy is small. Therefore, the frictional noise is rubbing noise, which is of a low level. (3) When the coefficient of friction grows great as the result of the tip of the rod being worn, the rod vibrates in the lateral direction as in the fundamental mode. Thus the vibrating energy increases and the frictional noise changes to the squeal noise, the sound pressure level of which is higher than the rubbing noise by 20-30 dB. These lateral vibrations seem to be self-excited vibrations caused by the friction.

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Dynamic characteristics of air-lubricated slider bearings operating under submicron spacing conditions are investigated theoretically and experimentally. From the modified Reynolds equation, considering slip flow effects, the properties of air film stiffness and damping are calculated in the frequency domain by small perturbation method and finite difference method. Influences of the molecular mean free path on the dynamic characteristics of air-lubricated slider bearings are discussed and a design method for high performance slider bearings, operation under submicron spacing conditions, is presented. Experimental data on the frequency response of the submicron slider spacing are in good agreement with the analytical results.

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Based on the approach to average out the inertial forces across the film thickness, modified Reynolds equations and their boundary conditions are introduced to evaluate the influence of the inertia forces of a gas film on the dynamic properties of an externally pressurized, gas lubricated, parallel thrust collar bearing with multiple holes admission. From comparison with the experiment it is concluded that the influence of the film inertia forces on the damping characteristics is considerable, and that the presented modified Reynolds equations and their boundary conditions yield good predictions of both the bearing stiffness and the damping coefficient in a wide range of designing conditions.

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Experimental studies to improve the load carrying capacity of plastic gears are presented. In the first place, the load test of nylon gear, which have the same cutting as steel gears, is tried and the limit value of power-transmission and the distribution of temperatures which rise under no lubricant are examined. In the next place, after the consideration of the temperature distribution in gear toot, the load test of nylon gears which are cut with counter-crowning is tried. It is confirmed that these gears are able to be used for power-transmission under limited conditions.

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