Low cycle fatigue tests were performed on several kinds of metal materials, and fatigue life was considered in terms of cyclic hardening property. The cumulative plastic strain energy to failure increases with a decrease in the plastic strain range controlled. The rate of the increase in that amount is influenced by the slip character of materials. Such a difference in the rate is reasonably interpreted by considering the shape of stress-strain hysteresis loop dependent on the slip character. A new criterion for low cycle fatigue was proposed on the basis of the effective plastic strain, ε_pe which is obtained through an analysis of the profile of the hysteresis loop. A simple equation of ε_pe·N_f= Constant is established in the life range from 10³ to 10⁷ cycles. This means that fatigue failure results from the linear accumulation of the effective plastic strain during strain cycling.

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Rotating bending fatigue tests were carried out, using the plain and notched specimens cut out from a rolled steel in the rolling and thickness directions and heat-treated in order to obtain three kinds of hardness. The heat-treatment done before turning, did not change the shape and distribution of inclusions. The main results obtained are as follows: 1) The anisotropy of fatigue limit increases as the hardness of material increases. This phenomenon is explained from the fact that the notch radius at the branch point changes with the hardness of the material. 2) In a high-hardness material, the notch radius at the branch point is extremely small and hence the anisotropy of fatigue limit does not disappear unless the notch radius is made extremely small.

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Low-cycle fatigue tests and sustained load tests of a high-strength steel (SNCM8) sensitive to stress corrosion cracking (SCC) have been carried out under various hydrogen contents. The threshold stress intensity facto for cyclic SCC under cyclic stress K_FSCC is smaller than the threshold value for static SCC under sustained load K_ISCC, K_FSCC being smaller with an increasing hydrogen content. In a steel tempered from a low temperature no hydrogen embrittlement is caused until diffused hydrogen is concentrated into a plastic zone at crack tips under small hydrogen content, so that the influence of stress waveforms becomes identical with that in a usual corrosion fatigue. Under high hydrogen content cyclic SCC plays a predominant role and a holding period during one cycle most enhances the crack growth. In a steel tempered from a high temperature the corrosion fatigue crack growth characteristics are the same as those in a usual low-strength tough material.

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Solution is presented, with in the classical theory of elasticity, for a class of asymmetric problems of an annular crack in an infinite elastic solid under shear. For the case when the components of the displacement on the crack face may be expressed in the form of appropriate Fourier series, the problem reduces to consideration of an infinite system of algebraic equations. Numerical results are presented for the stress intensity factors and the distribution of stresses and displacements on the crack face.

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The rotating strength of a circumferentially fiber-reinforced disc is limited by the radial strength of disc material. To increase the radial strength of the disc additional radial fiber-reinforcement, fiber-reinforcement tangential to the inner hole, and lamination-reinforcement with in-plane isotropy of discs are studied theoretically and experimentally. A method of laminating -reinforcement of a circumferentially fiber-reinforced disc is proposed.

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It is desirable in the moire method that fringe patterns with narrow fringe widths be obtained in order that the experimental accuracy may be raised. For this purpose special grids with different widths of bright and dark regions are useful. In this paper, new equations for determining simply the fringe widths formed by the grids with large pitches are proposed considering the widths of grid lines. These new equations are applied to several cases of special grids, and it is confirmed that new equations are valid experimentally. Besides, new fringes (false-bright fringes) are found to exist, and the nature of these fringes is examined.

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In this paper, the dynamic displacements and stresses in a circular cylindrical shell of finite length with both ends clamped, which is suddenly subjected to radial concentrated loads on its surface, are analyzed on the basis of Flugge's shell theory with use of the Laplace transformation. As a result, it is shown that Donnell's shell theory, which is treated in the previous paper, yields good results if the length of the shell is short or the thickness is thin using Flugge's theory as the standard of comparison, and the values of the dynamic maximum stresses are scarcely affected by the axial and circumferential inertia forces of the shell but the values of the lowest frequencies and the transient responses of the stresses are much affected thereby.

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In the present paper, the problem of thermal stresses in an infinite plate with an infinite row of circular holes, which are filled with elastic inclusions of another material, and subjected to uniform heat flow of temperature gradient μ in the direction of y-axis is treated. The analysis is developed on the basis of Airy's stress function in the generalized plane stress and by applying periodical harmonic function as the foundational function to obtain the temperature and stress functions. The successive approximation is adopted for the determination of unknown coefficients involved in the solution. Numerical calculations are worked out in some detail in order to clarify the effects of an infinite row of circular inclusions.

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This paper discusses the dynamic stress concentrations in bars with various bends. The flexural wave propagating along the bar which vibrates in an arbitrary direction is considered as an incident wave. Since the bar has bends, this incident wave induces longitudinal, torsional and flexural waves at these bends. In this paper, the elementary bar theory is applied for longitudinal and torsional waves, and the improved bar theory in which the effects of rotatory inertia and shear deformation are considered is applied for flexural waves. The analytical results for general problems are obtained, and the numerical calculations are carried out for cases of a circular arc bend, and L-bend and a Z-bend bars.

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Classical photoelasticity can be extended to analyse the stress-strain fields in viscoelastic materials. In this photoviscoelastic analysis, it is necessary to record and approximate with mathematical formulae a complete time history of the mechanical and optical characteristic properties of the viscoelastic materials. A new procedure, where the nonlinear minimization technique "SUMT" was utilized, was proposed to approximate those properties with Prony series representations. This procedure has been proved to be very rigorous and effective by applying it to two polymers, polyurethane elastomer and epoxy resin. Furthermore, it was considered appropriate to regard these two polymers as rheo-optically simple materials. Thus, their mechanical and optical behaviours were linear and the principle of reduced time (or time-temperature superposition principle) could be applied well.

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It is the object of this paper to study the stability of a complete elliptical plate restrained elastically against rotation along the boundary ellipse. On the basis of the ordinary thin plate theory, the buckling condition for the elliptical plate subjected to uniform compression in its middle plane is derived with use of trigonometric functions, hyperbolic functions, Mathieu functions and modified Mathieu functions which are the solutions of the equilibrium equation of a buckled plate. Theory is developed by paying attention to the orthogonal property of Mathieu functions. The lowest eigenvalues for the buckling mode symmetrical about both axes are presented in tables for a variety of aspect ratios, degrees of edge restraint and Poisson's ratios. Discussion of the degenerate case to a circular plate is also included.

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In measuring the aerodynamic damping characteristics of a cascade, when the air velocity is so high that the compressibility of the air can not be ignored, the vibration frequency becomes very high in order to keep a certain value of reduced frequency, and it is difficult technically to make all the blades in the cascade vibrate at the same time at so high frequency. In the method mentioned here, only the center blade in cascade is vibrating and the others are at rest, and the unsteady forces induced on the vibrating blade and other neighbouring blades at rest are measured and they are linearly combined with arbitrary interblade phase angle, thus the unsteady forces are equivalent to the one in the case when all the blades in cascade are vibrating at the same time with arbitrary interblade phase angle.

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The almost existing methods for analysing an unsteady two-dimensional cascade flow have treated the case of a plane flow. In this paper a method for the cascade flow on an arbitrary revolutional flow surface with an arbitrary varying passage height was proposed. In the method equations in terms of the vorticity component ζ normal to the flow surface and the stream function ψ are used. The equation for ζ is independent of the inclination of vorticity vectors and is calculated by a convective-difference scheme. The equation forψ is solved by using the Galerkin method. The treatments of trailing vortices were also developed. The method is applicable to the flows for arbitrary varying flow rates and rotor speeds and for non-uniform upstream velocity profiles due to the wakes. A numerical example of the flow with a sinusoidally oscillating flow rate is shown.

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Experiments on radial thrust in centrifugal pumps with a single-vane impeller are carried out. Three impellers with different subtended angles of vane and two delivery casings, i.e., volute casing and circular one, are designed. In the experiments the effect of the subtended angle of vane and that of the geometry of a delivery casing on radial thrust are examined. An analysis is also made to calculate the radial force acting on a single-vane impeller. From the present analysis and experiments, the following results are obtained. (1) It is confirmed that the radial thrust consists of the force caused by a delivery casing and that caused by an impeller itself. (2) The magnitude of the radial thrust in the case of the circular casing is less than that in the case of the volute casing. (3) The effect of the subtended angle of vane on radial thrust is small.

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This paper is concerned with the theoretical and experimental investigations of the accelerated critical air flow and heat-transfer characteristics in the divergent nozzles in which a sonic point exists midway between the inlet and the exit of nozzle fully taking into consideration the viscous effect. The compressible laminar boundary layer equations are solved numerically using a finite difference method, and a chart of the sonic line and the critical flow rate in a divergent nozzle are shown. The numerical solutions of the local and the mean Nusselt numbers of a critical nozzle are in good agreement with the experimental results. The range of critical divergent nozzles in which a laminar flow extends over the whole region of the nozzles is determined experimentally by the nozzle characteristic number and the divergent Reynolds number.

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The entrainment flow rate distribution, the gas velocity profile, and the concentration profile of droplets across the channel cross section in fully developed region of a horizontal rectangular channel of 150mm width and 50mm height were measured. The concentration profile of droplets was expressed by a simple equation based on a constant diffusion coefficient model. From this equation the effects of gravity and turbulent diffusion of droplets on the concentration profile were evaluated. The characteristic mean setting velocity of a group of droplets with various diameters was derived, and using this value the mean diffusion coefficient of the group of droplets was obtained.

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The transient behavior of a gas slug with rapid growth, which is encountered in evaporators operated under the atmospheric pressure, was investigated using a simulated flow system of air-water. The growth of a gas slug is considered to be brought about in two stages: the first is caused by an instantaneously enhanced pressure due to violent evaporation in a highly superheated liquid, and the second by a rapid decrease in static head as the gas slug ascends the vertical tube connected to the water-separator kept at a vacuum. The simulation of the first stage of expansion was made by introducing a gas slug, having a greater pressure than that of the water near the gas slug, into the test tube. It was observed that the gas slug flows upwards generating a damped oscillation: i.e., the tail end of the gas slug ascends linearly, but the top fluctuates remarkably. An analysis proposed of this transient flow can predict the complex motions of the gas slug with sufficient accuracy.

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An experimental apparatus for the supersonic flow of a spray-type two-phase (gas-liquid) fluid (the supersonic two-phase fluid tunnel) was made to investigate the compressible properties of this two-phase fluid. As for this supersonic two-phase fluid flow, the separate velocity of gas-phase and liquid-one, the ratio of gas-liquid mass flow rates, the ratio of gas-liquid volumetric flow rates, the gas-liquid volumetric ratio, the static pressure in the downstrem and the upstream of shock wave, the stagnation pressure in front of the blunt body, etc. were measured in this supersonic two-phase fluid tunnel and from these measured values, based on the theoretical treatment of this compressible two-phase fluid, the Mach number of this flow, the velocity of sound in this two-phase fluid, etc. were calculated. Comparisons between the experimental values and theoretical ones were done from a physical point of view. The experimental results fairly well coincided with the theoretical predictions.

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This paper deals with the stability problems of an asymmetric flexible rotor supported by asymmetric bearings. In a previous report the equation of motion of the rotor system is expressed as a time variant partial differential equation and it is transformed into infinite time variant ordinary differential equations. Then the stability of the system is theoretically and experimentally discussed on the parametric resonance, subharmonic resonance and so on. In this paper the instabilities caused by combination resonances are dealt with and the following results are derived. In addition to the conventional parametric resonances and subharmonic resonances, a sum type of combination resonances occurs, but a difference type of combination resonances does not occur in this system.

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Unbalanced vibration and way of balancing of a flexible rotor supported at its both ends by members having any mechanical impedances are studied theoretically by aids of 'forced mode' method, and the results are further verified by experiments. Following facts are revealed and confirmed. (1) Vibration of the system can be expressed theoretically in a serial form, consisting of two parts of different natures. The one is the term influenced by dynamic character of the supports and the other coincides with that of 'simply supported' (i.e. supported by pinned-pinned ends) rotor. (2) If the rotor is balanced in 'simply supported' modes combined with dynamic balancing, the state of balance is maintained on any other supports having different mechanical impedances. (3) The rotor can be satisfactorily balanced only by measuring the vibration of the shaft and bearings at a speed, without knowing mechanical properties of the supports.

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Effects of the gyroscopic moment on the nonstationary vibration, which occurs when a rotor passes through its critical speed at a uniform acceleration rate, are analyzed. The numerical integration results show that the gyroscopic moment makes the maximum amplitude small and makes the rotational speed, where the maximum amplitude occurs, high comparing with the results of a single-degree-of-freedom system. These phenomena may be explained by assuming that the acceleration rate in the gyroscopic system becomes large in appearance. Formulas for the imaginary acceleration rate and the maximum amplitude are derived by considering both the nonstationary vibration of a single-degree-of-freedom system and the change of the natural frequency of the gyroscopic system. The estimated maximum amplitudes are compared with the numerical ones.

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By using the modified Reynolds equations and their boundary conditions which have been proposed in Part I[1], influences of the gas-film inertia forces on the whirl instability and on the plane vibration in externally pressurized, gas lubricated journal bearings are analyzed. Analytical results agree well with the experimental results, and the following are concluded: 1) The inertia forces raise the whirl ratio and the damping coefficient considerably even if the bearings are normally designed. 2) This is remarkable when the feed hole diameter, the number of feed holes, the bearing clearance and the supply pressure are large. 3) The proposed modified Reynolds equations and their boundary conditions yield good predictions of such characteristics in a wide range of designing conditions.

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In this paper, a theoretical analysis of the radial spring characteristics of a ball bearing is presented, based on the studies by Perret/Meldau. We make clear 1) an improvement of the non-dimensional expression proposed in the former papers, 2) mean characteristics of fluctuation due to the change of configuration of balls, expressed as functions of a single variable: [radial clearance/(radial load/number of balls)^2/3], and their approximate formulae (accuracy of about 0.2%), 3) exact solution when only two balls are loaded and 4) modification of the above results (2) by a function of number and revolution angle of balls, which is available for general cases. Also numerical examples of the motion of inner ring and the differential stiffness are shown.

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This paper is concerned with synchronization of rotating machines connected by alternating flow hydraulics. Taking account of the interaction between driving and driven machines, synchronization phenomena are analyzed by the averaging method and the synchronizing phase angles are derived. The stability of the steady-state solution is investigated by means of Routh-Hurwitz criterion. Moreover, the influence of initial conditions on the steady-state rotating motion is considered on the phase plane and critical domain is discussed.

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Rigid contact wires used in monorail and new transportation systems are disadvantageous in that they are liable to cause interruption of pantograph contact, generate large noise, and shorten the service life of the slider. In an attempt to overcome these problems, a new type pantograph was trially manufactured and subjected to various tests with a newly installed rotary disk type equivalent testing equipment. When the new type pantograph was combined with a slider of graphite-disprsed copper type casting alloys, it was found, noise at a distance of 1 m from the sliding contact surface at 60 km/h was about 17 dB lower than with a conventional pantograph. Also, the factor of contact interruption was substantially reduced and the slider life vastly prolonged.

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A new graphic method is proposed, in which the hobbing state in the unfinished tooth space can be easily illustrated through simple calculations and with only one tooth profile template. This method is useful not only in the estimation of the cutting thickness, length and zone in various hobbings but also in the forecast of the chip flowing on the rake face. The tooth wear can be also related analytically with the cutting amount and the chip flowing. Additionally, several tooth profiles developed for the anti-wear purpose are discussed.

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The present paper makes it clear that Coulomb friction which acts on slideway of machine tool has an ability to damp a fluctuating external force and this capacity can be evaluated as an equivalent viscous damping which consumes the same amount of energy with the friction during one period of vibration. It is shown that the dynamic stiffness of a feed driving system attached with a hydrodynamic slideway, which usually possesses Coulomb friction, can be theoretically estimated if the corresponding equivalent damping is considered by the present theory.

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A feed driving model facilitated with a hydrodynamic, a half-floating, or a hydrostatic slideway was prepared and its dynamic stiffness was measured under the condition that when a Coulomb friction acted on the slideway, an exciting force, and a feed rate were varied. It is verified that the previous theory can well explain the experiment, that is, the dynamic stiffness can be estimated quantitatively if an equivalent damping capacity is evaluated from the Coulomb friction during vibration, and that, for a practical application, this friction can be replaced by the one somewhat smaller than the steady friction force measured for a steady feed.

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The tooth profiles of the finish rolled spur gears are analyzed theoretically by assuming a simple deformation model. under the conditions that the center distance is kept constant during rolling process or that the rolling load is kept constant; in each case the work is driven externally or free. Then the effect of the rolling methods mentioned above on the finish rolled gear tooth profiles is discussed. The finish gear rolling experiment by two opposed dies is done in the case that the work is driven only by a die. The theoretical tooth profiles are compared with the experimentally rolled tooth profiles and this deformation model is proved to be useful to determine theoretically the modified tooth profiles of the dies which produce the finish rolled gears with the required tooth profile accuracy.

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The authors investigated the influences of difference in hardness of mating gears and their roughnesses on the surface durability, using hobbed gears (gear ratio 1:1) and rollers with various roughnesses. It is found that the pitting life of hobbed gears with combination of unequal hardnesses is shorter than that of ones with equal hardnesses. And, it is considered that the surface of softer steel is damaged by the surface asperities of harder steel when the initial roughness is large. furthermore, form the results of roller tests, it is found that the hardness increases at the surface of softer steel with the number of cycles. This fact is critical for the initiation of fatigue cracks. Therefore, in the case of H_B≈340 (hardened and tempered) steel, it is clear that pitting is much influenced by the relationship between difference in hardness and initial surface roughness.

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The oil film thicknesses between the tools and the workpiece and their changes during a cup drawing operation are analytically predicted to facilitate estimating the effects of the process variables on the lubricating conditions, including the blank holding speed, the time elapsed after setting the blank holder until the beginning of the punch penetration, drawing speed, lubricant viscosity, blank material and the geometries of tools and workpiece. It is experimentally shown that the greater is the ratio of the calculated oil film thickness to the maximum surface roughness which would result on the deforming workpiece separated from the tool by a very thick oil film, the smaller are the contact ratio and the friction between the tool and workpiece. The experiment also shows significant changes in the lubricating conditions on the die flat and on the die profile during the process.

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