The elasto-plastic fracture mechanics approach to fatigue crack propagation gives the following relationship ; Δa/Δn = c'·w^*m _L or Δa/Δn = c·w^m_L, where, Δa/Δn ; propagation rate of fatigue crack, w^*_L, w_L ; cyclic plastic zone length and monotonic plastic zone length at crack tip, respectively (w^*_L∝w_L is assumed), C, _C', m ; material constants, which are related to the ductility, elastic modulus and yield strength. In addition to above facts, authors insist that the plastic constraint around the crack tip is important in fatigue crack propagation, for the following reason ; the larger the plastic constraint, the faster the propagation rate of fatigue crack, because the crack propagates in plane strain state without ductility ; and the less the plastic constraint in plane stress state, the slower the rate. The transition phenomena exists between both states, depending on plastic zone width and the thickness of the plate. Above mentioned facts can be proved experimentally.

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An anisotropic yield condition and a flow rule of metal for various complex loadings were investigated in the three dimensional deviatoric vector space. The yield function was derived by considering the distortion and the translation of the yield surface. The configuration of distorted yield surface was represented as a set of points on a series of ellipses whose lengths of the minor axis were changed as a function of the co-ordinate on the symmetrical axis of the yield surface. The subsequent yield surface after the pre-strain path with a corner was assumed to translate in the direction of the stress increment vector. The flow rule was introduced from the normality rule of the plastic strain increment. The yield surfaces and the stress-strain relations along the proportional pre-loading path, the pre-strain paths with a corner and the cyclic loading path were calculated by using the derived yield functions. There was good agreement between the results of calculation and of experiment for brass.

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A structure whose load-displacement curve due to geometry change after initial yield is expressed approximately by a cubic nonlinear curve is represented by a dynamically equivalent system consisting of a nonlinear spring and a slider, and its dynamic response to the impact of a moving mass is analyzed by means of successive approximation. This analysis is carried out with a structure made of a rigid-perfectly-plastic material, but the results are applicable to the case of an elastic-perfectly-plastic material. Numerical examples are given for a U type beam subjected to an impulsive loading at the tip.

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Experimental study on the high frequency elastic wave mode propagating in a long circular aluminum rod was executed using new devices. A four terminals type piezo-electric transducer was used to observe the phase of vibration of each mode at the end of the rod and to classify directly the wave modes. Experimental results are as follows. Good coincidence between the theoretical group velocity and the experimental propagating velocity in each mode is obtained within the experimental errors. The mode coupling phenomenon is observed at the critical frequency, and also observed in the condition of the F2 mode type impulse. The directions of the neutral surface of vibration in the F1 modes are different from each other. The directions in the F1(2) mode and the F1(3) mode are perpendicular and parallel to the direction in the F1(1) mode respectively, and each direction does not change with a change of frequency.

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Dynamical behaviours of two beams connected with a set independent springs and subjected to an impulsive load are investigated taking the effect of the mass of springs into account. The solution is formulated by the method of the Laplace transformations with respect to both time and space variables, which allows one to analyze all the major performance characteristics in the system subjected to an arbitrarily distributed impulsive load. As a numerical example, the case of a concentrated half-sine impulsive force applied to the mid point of the upper beam is treated. It becomes evident that the amplitudes of deflection and bending moment in the beams decrease as the mass of the springs increases. The response curves are also compared with those for the mass-less springs of Wikler type. It is found that the similarities between the two responses diminish as the mass of the springs increases.

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The present paper investigates the characteristics of the critical velocity of a load moving on a beam supported by an elastic stratum. In the analysis it is assumed that the stratum is a continuum which is homogeneous, isotropic, and linearly elastic. Both welded and smooth contacts between beam and foundation are considered. The influence of the density and the thickness of a foundation on the critical velocities is studied. The results are compared with those obtained from the Winkler assumption. It is found that the critical velocities for smooth contact are not so different from those for welded contact. The critical velocities vary considerably with the values of the density and the thickness of the foundation. The velocity by the Winkler assumption and the one by the continuum theory are relatively close to each other when the foundation is a light and thin layer though they are generally different from each other.

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This paper deals with the flexural vibration s of a circular plate under various mixed boundary conditions. The mixed constraint conditions for the displacements of the plate on its circumference are formulated by means of the weighted residual method, and the corresponding dynamical boundary conditions are derived from the Lagrangian by the multiplier method in the calculus of variations. Numerical calculations are carried out for three examples ; one is of a circular plate clamped on part of its boundary and simply supported on the remainder, another, partly simply supported and partly free, and a third, partly clamped and partly free. an experiment is made on the last example, and the experimental values almost agree with the calculated values.

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For the purpose of predicting flow instability in sodium heated steam generators, a theoretical model was presented for boiling flow oscillations in parallel channel systems, and a computer code was developed. The propagation of thermal-hydrodynamic disturbances was described with a matrix transfer function, and the modes of proper oscillations were obtained by solving a characteristic equation, in which the boundary conditions were imposed on the transfer function. Eigenvalues and patterns of the properscillations determined for instability revealed that the frequency given by the eigenvalues is in good agreement with that observed in the performance of a small size steam generator.

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Turbulent boundary layer developing along a long streamwise bar with a square cross section placed on a flat plate was investigated experimentally. Measurements were made on the distributions of mean velocities, turbulence intensities and wall stresses. Main results obtained are as follows ; Near the streamwise edge and corner, secondary currents are generated whose directions near the bisectors are away from and toward the wall respectively. The wall region still exists near the edge and the corner, but the logarithmic straight part in the defect law representation undergoes an upward or downward shift. The Preston tube measurements showed that the mean value of the wall stress in the region affected by the bar agrees well with that in the two-dimensional region, which makes it possible to calculated the total frictional drag of this wall from the flat plate formula. usefulness of the approximated momentum integral equation in this case was examined using the experimental results.

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The characteristics of pipe-orifice flow in the free-molecule flow regime are analyzed by the kinetic theory of gases. Main attention is paid to number flux distributions of incident molecules on the pipe wall, which are given by simultaneous integral equations. The numerical solutions show that the interaction region between pipe flow and orifice one exists always at the vicinity of the orifice plate, and depends strongly on the ratio of the pipe-length to the pipe-diameter but weakly on the ratio of the orifice-diameter to the pipe-diameter. The analysis also shows that the conductance of a pipe-orifice having a finite pipe-length should be calculated exactly instead of bureau's approximate formula based on the assumption of no interaction, since the effects of the interaction become relatively large as the pipe-length decreases.

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The static and dynamic performance characteristics of a fluidic angular rate sensor were studied both theoretically and experimentally. It seems that the total time delay of a vortex rate gyro is composed of the time delay associated with the development of a stabilized tangential flow at the vortex chamber periphery plus the pure delay time associated with the fluid transport phenomenon. By this theoretical analysis, the transfer function of a vortex rate gyro was obtained as Ae^LS/(T₂s +1) and thereby, the effects of the vortex rate gyro configuration and supply flow rate on the pure delay time L, time constant T₂ and output sensitivity A were clarified. Experiments were conducted varying the vortex chamber thickness and the supply flow rate. It was found that experimental pure delay time L and time constant T₂ almost coincide with those obtained theoretically.

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Although it has been known that the oil hydraulic jet-pipe servomechanism may often fall into instability, the details of the phenomenon have not yet been clarified. In this study, the instability which occurs in an oil hydraulic jet-pipe servomechanism with a force feedback is treated theoretically and experimentally. The results obtained are summarized as follows : (1) A stability condition of the system is derived. (2) If the condition mentioned above is not satisfied, the system falls into a sustained oscillation, whose amplitude and frequency are uniquely determined by parameters of the system. (3) Under the design condition commonly used, the system is liable to instability. (4) When the jet-pipe is used in a submerged state in oil, flow forces on the jet-pipe appear. And in some cases these forces may cause instability to the system.

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In this paper, the authors have investigated the phenomena of thermal shock in cam curve type radial piston motors which are set in the environment of low temperature, and they show the methods to analyse the variation of clearance with thermal expansion as the temperature changes in both steady and unsteady states. The experimental results are obtained that the annular clearance comes in the hydraulic motor suddenly heated by oil of high temperature. It is made clear that the thermal shock is due to the difference of material thermal expansions between inner and outer parts of the cylinder. Thus some conclusions about prevention of thermal shock are reached.

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In order to simulate the thermo-hydrodynamic conditions at reactor power excursions, a test piece was placed in a forced convective channel and heated with exponential power inputs. The boiling heat transfer and the burnout heat flux under the transient heat input were measured, and pressure and water temperature changes in the test section were recorded at the same time. Following experimental results were obtained ; (1) Transient boiling heat transfer characteristics at high heat flux stayed on the stationary nucleate boiling curve of each flow condition, or extrapolated line of the curves. (2) Transient burnout heat flux increased remarkably with decreasing heating-time-constant, when the flow rate was lower and the subcooling was higher. (3) transient burnout phenomena were expressed with the relation of (q_max-q_sBO)_T = constant at several flow conditions. This relation was derived from the stationary burnout mechanism of pool boiling.

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Since the flow velocity in a free convection from a vertical plate is comparatively small, it may be considered that the influence of the divergent flame propagation on the ignition is negligible except in the case of very low burning velocity, and then the inflammable conditions are determined only by the hot surface. It this experiment, changes in the flow and the composition of mixture around the plate in every experiment under the same conditions are small compared to those in a forced flow. Therefore, it is relatively easy to know the qualitative characteristics of ignition. From the point of view described above, the authors arranged the experimental results making use of the relation between experimental parameters and critical ignition temperature obtained from a numerical analysis of the fundamental equations and showed that the experimental results agreed well with theoretical prediction.

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The temperature of a premixed gas during the compression stroke in a rapid compression machine and an engine may be measured by using infrared radiation. The infrared radiation pyrometer mentioned in this work employs the ratio of the absorptivity to the emissivity of water vapor at 2.7μ band. The spectrum at 2.7μ band is affected by the presence of CO₂ as well as the water vapor density. Besides, the dry air which is inactive in the infrared region may change the spectrum. Therefore, the influences of the change of the spectrum on the pyrometer reading were checked under the following conditions ; (1) variation of water vapor density, (2) variation of CO₂ density, (3) mixture of the two gases and (4) pressurization by dry air. No influence upon the measured temperature was perceived in the experiment under all these conditions.

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In the planetary gear, the inequality of load distribution arises on each planet gear because of random errors of manufacture and assembly. This phenomenon results in an increase of load to each part, the occurrence of vibration, and a drop in efficiency of planetary gear systems. Though there are a number of studies which are connected with load distribution, many of them are static studies. However, in fact, the dynamic behavior of load distribution in driving is complicated because of the influence of the deformation in each part, dynamic characteristic of the system. Therefore, to explain these relations, a systematic experimental work was carried out using Stoekicht planetary gear(Type 2K-H) with spur gears. Consequently, the following items are explained in this paper : (i) The mean values of load distribution among the planetary gears are nearly equality, but variations of dynamic tooth loads grow large in the high-speed range. (ii) Even if load distribution is equality, it happens that gear tooth dynamic loads largely.

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The purpose of this study is to examine a new powder compacting method which will be described later and to investigate the properties of the compact produced. The process is as follows. A mixture of the spherical cast iron powders of about 0.2 mm in diameter and water glass is poured into a plaster mold, compacted under a low pressure, solidified by carbon dioxide gas and sintered. Then the pores of the sintered product are filled with liquid copper. The results are as follows. The sintered products containing water glass 2% compacted under 50kg/mm² sintered for 3 hours at 1, 250°C, indicate a shrinkage of 1.6% in the direction of compaction after sintering, a porosity of 40% and a compressive strength of 2.0kg/mm². The specimens made by injecting copper into 75% of all the pores of the above sintered product for 3 hours at 1, 150°C indicate a dimensional change of 0%, a porosity of 2%, a tensile strength of 20kg/mm² and a compressive strength of 72kg/mm² with 40% elongation.

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