Influences of stress wave forms and superposition of vibratory stresses at the periods of the maximum stress under a low-frequency varying load on cyclic SCC have been investigated with a high-strength aluminum alloy, and the loading condition dominating over cyclic SCC and the competition between cyclic and dynamic SCC have been discussed. The threshold stress intensity factor for cyclic SCC, K_max = K_FSCC, is independent of hold time at the maximum stress, but increases with a decrease in varying load rates per time K^^·. At higher ΔK_%lt;eff%gt;, however, da/dN is enhanced with a decrease in ΔK^^·_%lt;eff%gt; i.e., at longer rise time; this is similar to those of conventional corrosion fatigue. On the other hand, the superposition of vibratory stresses promotes corrosion products-induced wedge effects with K_op =K_max. In this case, K_FSCC is determined by the threshold stress intensity factor, K_DSCC, for dynamic SCC under the secondary vibratory stress condition.

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This paper is concerned with the beneficial effects of additional holes or indentations on fatigue crack propagation. Two indentations facing each other at the tip of a crack are especially effective for retardation of crack propagation. The effect of the indentations can be approximately estimated from the existence of residual stresses produced by the indentations.

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The present paper deals with the tensile strength and fracture mode of SiC fiber exposed to a hydrostatic pressure, isothermal heating and liquid aluminum environment. These conditions are sometimes encountered in FRM fabrication by a liquid infiltration method. The results of the tensile-test showed no fiber degradation in a given isothermal heating and hydrostatic pressurizing, but the fiber exposed to the liquid aluminum environment degraded with an increasing exposure time. And a fractgraphic observation revealed the following. As for the original fiber, the isothermally heated fiber and the hydrostatically pressurized fiber, the cracking occurred from the inner defect of the fiber or from the surface defects. Most of the fibers failured by the inner defect are stronger than those by the surface defect. On the other hand, for the liquid aluminum exposure the fibers which the fracture originates from the reaction product formed on the fiber surface with the aluminum increased in number as the exposure time increased, and after 2min exposure all the fibers fractured by the reaction product.

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Adiabatic elastic constants for aluminum are calculated by a pseudopotential method in various atomic volumes, which correspond to arbitrary pressure and temperature. A temperature dependence of the ideal strength and the surface energy is evaluated from the stress-strain relation in <100> deformation mode up to the fracture strain. Using Lindemann's low, a pressure dependence of the melting point is also evaluated from the elastic constant C₁₁ at the melting temperature and is compared with existing experimental data. Finally, a method to obtain isothermal elastic constants is discussed by using Gruneisen parameter defined for <100> deformation.

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The stress concentration problem of a strip with a finite row of circular holes subjected to in-plane-bending is solved numerically. It is assumed that the holes have equal diameters and are placed on a center line of the strip at equal intervals. A numerical method is adopted in which a general form of stress function expressed in the polar coordinates and its transformed equation in the rectangular coordinates are recurrently used; the former is used in the method of Fourier analysis to satisfy the boundary conditions on the circular edges, and the latter is used in the method of Fourier transform to satisfy the boundary conditions on the rectilinear edges. Stress concentration factors are calculated and summarized in some diagrams. The calculated results coincide well with solutions obtained by the finite element method and experimental data obtained by electrical resistance strain gages.

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A numerical method of calculation by the finite difference method to solve an elastic stress analysis problem of rectangular domain is presented, and a scheme for treating the neighborhood of a crack tip is proposed. By using this method, the stress intensity factors of rectangular plates and strips with one or two cracks in mode I and mode II are calculated, and these results are compared with results by some other methods presented before to show the validity of this method.

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The stress distribution in threaded portions of bolt and nut being fastened by applying torque to nut is analysed by FEM. The object of analysis is assembly of a bolt, a nut and a fastened plate, which are all treated as axi-symmetric bodies. Two methods of analysis are proposed. The first method is composed of an axi-symmetric analysis for the state generated by applying tension to bolt and an analysis of torsion for the state generated by applying distributed torque at the contact surfaces. The distributed torque is approximately estimated from the distribution of the normal stresses generated at the contact surfaces by the axial tension. The second method is a three-dimensional analysis, where effects of lead angle are considered only through the relationships of forces acting on the pressure flank. From some calculations by the above two methods, effects of the torque applied during fastening on the stress distribution are estimated.

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An automated system for a rapid and precise X-ray stress measurement using a microcomputer has been developed. A block diagram of the system and a flowchart for the stress measurement method are shown. Of the various methods, the one most suitable for the material to be measured can be programmed in this system. The residual stress in a hardened steel having a broad diffraction profile (half-width of 7.2^°) could be measured in six minutes with a small standard deviation of 13 MPa by the Gaussian curve method using the sin²ψ method. Both the oscillation and the fixed ψ methods, using the Gaussian curve method, allow the X-ray stress measurement of coarse-grained steels; the sin²ψdiagram obtained by these methods had a good linearity. The residual stress measurement of an annealed chromium powder gave almost zero stress values, -3.2 to 2.9 MPa depending on the method used, showing high accuracy of the system.

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A small-scale boundary solution system for the classical St. Venant problem with prismatic beams of arbitrary cross section is presented in this paper. Since the problem can be resolved into four trunk problems related to basic loading states, the entire solution is assembled with each solution. Each trunk problem can be dealt only with respect to the boundary of cross section, which simplifies the data structure required for computation.

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By using an unique half cut model of an oil hydraulic poppet valve, the cavitation phenomena were directly observed and the pressure distribution was measured in the metering restriction between the valve seat and the poppet surface. As a result of this research, the occurrence process of cavitation in a poppet valve and the effects of it on the flow performance were made clear. Also, the differences in a performance of cavitation between the diverging flow and converging flow were understood.

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The influences of the chamfer length of the valve seat on the flow performance and the cavitation phenomena of an oil hydraulic poppet valve are studied experimentally using the half cut model. It is made clear that the discharge coefficient becomes maximum when the ratio of the chamfer length S to the restriction height h is a specific value within 1≤S/h≤3 in the case of a diverging flow, and S/h≤1 in the case of a converging flow, if the valve lift x^^- and Reynolds number R^*_e are fixed. The critical cavitation number K_c also becomes maximum in the same range of S/h as the above. In the case of a diverging flow with chamfer length of S = (1 2.5)h, a periodic flow turbulence occurs at the restriction under some pressure conditions, and it induces an unusual sound noise like a whistling with resonant vibration of the oil column in the pipe line.

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The wall shear stress in an unsteady duct flow is determined by equalizing the pressure gradient calculated from the momentum integral equation to that from the energy equation. This method is applicable to an unsteady flow subjected to a relatively low acceleration in a duct with arbitrary cross-section. Consideration on unsteady laminar flows in a pipe and rectangular ducts with various aspect ratios reveals that the present representation for time-dependent wall shear stress is superior to the quasi-steady representation commonly used so far. This fact suggests that the present representation is more useful than the quasi-steady one in the turbulent regime too. Accordingly, the representation for unsteady turbulent flow in the above mentioned two kinds of ducts are derived.

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Neutral stability of Gortler vortices was experimentally and theoretically examined. By towing a concave wall of 500mm radius of curvature at a constant speed in a water tank, the neutral stability of the vortices in a low wavenumber region was experimentally determined by observing the behaviour of a given disturbance, which was introduced with a row of wings of finite span, by the hydrogen bubble technique. The neutral curves were calculated for two cases of parallel flow and non-parallel flow models. The present measurements are explained by the Smith model better than by the Gortler model.

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Interfacial shear stress was measured for a thin liquid film flowing concurrently with air flow under wide ranges of gas and liquid flow rates in which various kinds of wave structures of flow patterns are realized. The results are summarized as follows. (1) Interfacial shear stress depends on flow pattern besides the condition of air flow. (2) The waves on the liquid film are not equivalent to the roughness on a solid wall especially for a higher air flow even when the crests of waves on the film do not jut above the viscous sublayer. (3) A correlation for friction factor which is equivalent to shear stress was proposed for the cases of turbulent air flow.

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The generation of a disturbance wave on a liquid film flowing concurrently with a gas in a horizontal rectangular duct is analyzed theoretically based on the instability of both the dynamic and kinematic waves. The result shows that the occurrence of a disturbance wave strongly depends on a film thickness. The film thickness obtained theoretically by assuming both the liquid film and the gas flows being laminar is larger than the experimental value. Therefore, the experimental data on film thickness are used to predict the flow condition of transition from pebble wave to disturbance wave. A simple correlation for the P-D boundary is obtained which includes the effect of the duct height. Finally, the role of a disturbance wave in liquid film formation is also discussed.

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Characteristics of centrifugal pumps handling air-water mixtures are analyzed on the basis of a gas-liquid separated flow model, which is generally accepted in the analysis of the data on a two-phase flow in piping systems. And a method for predicting the pump characteristics is presented with use of parameters of friction-loss and shock-loss multipliers. Size of air bubbles flowing through pump impellers was measured. The bubbles in the inlet region of the impellers have an extremely uniform size with fairly small diameters. But in course of flow, the bubble diameter grows gradually due to coalescence of the bubbles.

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The visibility and the scattering particles of Laser Doppler Velocimeter are discussed in this paper. Using fine wires as seeding particles, the relation between visibility and the ratio of the diameter of a fine wire to the fringe width and that between visibility and the dimensionless aperture radius have been investigated experimentally. The results agree with the theoretical values of the cylindrical shape particle. The shape of output signal waves has been researched experimentally when two fine wires of same diameter and different diameters passed at constant interval in the interference fringes.

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Transient responses to sudden changes in pressure or flow rate in both single pipeline and series pipelines are theoretically studied under open-end and closed-end condition. A fundamental equation used in this analysis is the one for fluid line model in which the frequency-dependent effect of viscosity is taken into consideration. It is confirmed that the theoretical results well agree with experimental ones obtained under various system conditions and parameters.

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A single-stage transonic turbine was tested over a wide range of pressure ratios. The exit Mach number of nozzle and blade are supersonic at the design pressure ratio of 4.16. The measured performance was compared with the results calculated by a mean-line prediction method, using two kinds of loss systems. One is Ainley & Mathieson's system improved by Dunham & Came (AMDC), and the other is Craig & Cox's system (C&C). It was found that airflow characteristics and loss systems play an important role in estimating the performance of a transonic turbine, especially when nozzle and rotor row are choked alternately.

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In this paper, a new analytical method is presented for the boundary value problem of the non-linear unsteady heat conduction with temperature dependent thermal properties. Two non-equilibrium integral functions have been introduced: a function of the thermal conductivity Φ₁(φ) and a function of the heat capacity Φ₂(φ). By setting the integration intervals of these functions such as to satisfy the relation Φ₁(φ) = Φ₂(φ), the non-linear heat conduction equation could be linearized. This method is applicable to the cases such as linear, quadratic and exponential variations of the thermal conductivity and heat capacity.

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Experiments have been carried out on free convection heat transfer from horizontal cylinders in staggered arrangement. Average heat transfer coefficients of individual cylinders and the whole cylinder array were measured in order to clarify dependence of those coefficients upon the geometric figures including spacing and off-set distance between two cylinder lines. Visualization of flow fields around the array has also been tried to explain the heat transfer behavior of cylinders in array. The experiments show that there exist some optimum values of cylinder spacings and the off-set distances to increase the heat transfer coefficients and that the heat transfer promoting effect can be expected especially when the array is set between parallel walls.

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In the present work, an investigation was made on the heat transport through insulation powder evacuated under high vacuum, in which an aluminium powder was added for radiation shield. Experiments on heat flux in the powder were carried out from room temperature down to liquefied Belgium temperature, which enabled us to examine the relation between the heat flux and temperature. Furthermore, the general solution for total heat transfer for combined radiation and conduction proposed by Wang and Tien was applied to the powder, and was compared with the experimental results. We then quantitatively determined the roles of the contribution from both radiation and conduction and the effect of added aluminium powder, and investigated the basic heat transfer mechanism in the powder at low temperatures such as extinction coefficient for radiation and contact conduction between particles.

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In the previous paper the initial dispersion process of jet engine exhaust plume was discussed with the data of jet engine field test as well as those of the model test. The momentum dominant region in the jet was treated mainly, and the model test was carried out for a few nozzle heights over the ground board corresponded to the engine installing heights of the aircraft. There are considerable differences in the ratio of inertia to buoyant forces in the jet between the engine operating modes, i.e., in takeoff mode (TO) the inertia is dominant, while the buoyancy is dominant in idling mode (ID). These typical conditions of TO and ID modes were examined and the results are compared with each other and with those of field test. The source position of atmospheric turbulent diffusion after the jet dispersion is estimated from these results.

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The author showed in the previous report that the key factor must be the phase lag of the governing pressure taken at a narrow passage called subventuri beside a throttle valve, because the hunting disappears when the phase lag is minimized by displacing the pressure source to the common intake duct just down the throttle valve and the subventuri. In the present work, he experimentally determines the frequency response of the engine system and the one of the pneumatic governor system composing a closed loop, in order to verify the existence of hunting under the subventuri pressure control and its non-existence under the suction pressure control.

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With a target of developing a Stirling engine to be driven by waste heat of refuse incinerators etc. with the working gas such as sir or nitrogen, a displacer type engine was made on experimental basis, and its performance was tested. Air and nitrogen are cheaper and easier to handle than helium or hydrogen which is generally used as the working gas, but the flow resistance of the gas of such a kind is fairly higher than that of helium. In order to reduce the flow resistance, special perforated copper heat-transmitters were adopted as heater elements and regenerator matrices. Conveniently, the welding job required for making the heater of this type is comparatively little. The test showed almost satisfactory performance of the engine. However, it became clear that in order to raise the mean working pressure still more, the gas-seal device for the power piston should be much improved.

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For the purpose of suppressing the ground vibration as pollution, this paper presents both the design procedure and the realization of an active force control system, and also makes it possible to replace a conventional spring support with a rigid support of a vibrating machine. First, based upon the properties of an active force controller, the fundamental characteristics required for a dynamic compensator are shown. Then, with a view to designing the active force control system in terms of a feedback control method, a Nichols chart is modified so as to gain an appropriate compensation network. With the aid of the chart, the control system is designed, with the result that a sufficient suppression of an exciting force is verified experimentally. Next, in order to achieve a stable drive of the control devices, a realization of low gain compensator is presented. Finally, for the case where an exciting force has a sharp peak at a certain frequency, a method to produce notch effects is proposed.

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The practical problems in torsional vibration of Diesel engine shaftings might be almost completed by using the computer technique. Nevertheless, there is still some problem in them to examine more exactly the nonlinearlity of structural elements and an end-damper in the engine damping magnifications (EDM). First, the equivalent hysteresis (EH) shafting is defined through the transformation method of two stages from n %gt; 2 to n = 2 between stiffnesses and dampings. Second, the equivalence relation between multiple parton model and equivalent simple parton model is proved, where the parton here means the equivalently concentrated mass. Then, the EDM is defined on either shafting without an end-damper or one equipped with it. The illustration method of EDM is first developed on the former shafting, which is convenient and effective to explain the scattering spheres of Wilson's experimental values of 200 sorts of engines. On the latter one, it can be also illustrated to make the whole damping stress necessary to an end-damper estimated easily through another transformation method of two-stages, whether the damper is equipped or not, concerning the nonlinearity between shafting and an end-damper.

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It may be practical to apply a marking-off technique for manufacturing the restricting grooves designed on the bearing surface of an externally pressurized gas-lubricated bearing with surface-restriction compensation. The marking-off produces a triangular cross-section of grooves. In this paper, a simple, convenient method is introduced to evaluate the so-called equivalent clearance for the flow along the triangular grooves. then an externally pressurized gas thrust bearing with surface-restriction compensation through triangular grooves is analyzed using this equivalent clearance model. The design criterion of this type of the bearing is discussed from theoretical results of the fundamental bearing characteristics.

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This paper describes a method to correct structural errors in articulated robots. Structural errors, caused by a deviation of the actual parameters from the designed parameters, occur due to errors during assembly. There are two types of errors which reduce the absolute positioning accuracy of robots; one is an arm length error and the other is an angle error between neighboring arms. The arm length error has been extensively researched and corrected, but a means for correction of the angle error has not been completed yet. In this paper, these two types of parameters and a new algorithm to correct all structural parametric errors are introduced. Using this method, we achieved absolute positioning accuracy 100 times as precise as the conventional method.

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Laser-hardened S45C, SNCM439 and SMnC443H steel rollers and induction-hardened S45C steel rollers were tested using a sliding-rolling contact fatigue testing machine, and the surface durability and surface failure were investigated. The experimental results were discussed in terms of an amplitude of ratio of reversing orthogonal shear stress to hardness. The machanism of spalling failure of laser-hardened rollers was made clear, and it was recognized that the surface durability of a laser-hardened roller was possibly equal to or higher than that of an induction-hardened roller.

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Gears made of four kinds of low-alloyed steels with different hardenabilities were through-hardened in a cooling oil to investigate an influence of hardenability on gear distortions which is considered as a criterion for thickness of hardened layer. From the experiment, the gear distortions caused by the hardening are found to be related not only with the hardenability of the material, but also with the residual strain of dilatation curve. The reason why the gear distortions caused by through-hardening are not related only with the hardenability is in the existence of retained austenite. And there is a relationship between the product of ideal critical diameter and the residual strain on the dilatation curve, and the gear distortions caused by through-hardening. Moreover it is clear that grain size changed through annealing process affects gear distortions.

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Stress distributions in planet gears with a thin rim are analyzed by the photoelastic method and the following results are obtained: Although the position of the maximum stress occurring on a fillet varies with both the tooth load and the radial clearance between rim and gear shaft, it may be sufficient to consider the maximum tensile and compressive fillet stresses in the planet gear concerning the bending strength. In the case of a thin rim, if the radial clearance increases by more than a certain value, the stress amplitude on a fillet may increase rapidly and the value of the clearance may decrease when the rim thickness decreases.

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This paper presents a study on the effect of load variation on the bending fatigue strength of helical gears. A bending fatigue testing machine for cylindrical gears controlled by a micro computer was developed, and the bending fatigue tests of helical gears were carried out under a uniform cyclic load and a varying load which had the load spectrum of normal distribution. Various cumulative fatigue damage rules (Miner's rule, modified Miner's rule and VDI-Richtlinien 2151) were compared on the basis of the experimental results, and the effect of load variation on the bending fatigue strength of helical gears was clarified to a considerable extent. Furthermore the effect of understress on the bending fatigue life was investigated.

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This paper presents a study on dynamic behavior of thin-rimmed helical gears with various web arrangements. Natural frequencies of flexural vibration of gear body were measured and compared with the calculated results by Mindlin's method. The relations between these natural frequencies and spectra of circumferential, radial and axial vibrations were investigated. The circumferential, radial and axial vibration accelerations and the root stresses were measured under different running conditions by using a gear testing machine of a power absorbing type. On the basis of these results the effects of web arrangements on vibration and dynamic load were clarified to a considerable extent.

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This investigation intends to obtain the basic data for applying a newly proposed process utilizing a divided flow to actual gear-toothed machine part. In this first report, a two step forging method is used for the working of a spur gear and the possibility of cold precision die forging for the gear is examined experimentally, when a preliminary closed die forging is combined with the process utilizing the divided flow. In this experiment, the process has been successful in the complete filling up of materials into a die cavity under a low working pressure and is found applicable to various initial thicknesses of materials. Suitable restriction of a centripetal material flow, is found more effective for decreasing the working pressure and saving the material.

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The process utilizing the divided flow is applied newly to some machine parts such as a spline, a regular polygon and a spur gear with the purpose to clarify this useful process more universally. On the basis of the experimental data, its applicable range to these parts of various shapes and sizes is examined as compared with the respective expectations based on the upper bound theory. Through these examinations, it is concluded that the process utilizing the divided flow enables the precision die forging of the adopted parts under a lower working pressure and also enables the forging of the parts of various shapes and sizes within the range of similar working pressures. The process utilizing the divided flow, therefore, has wide applications to the cold precision die forging.

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In this paper, a mathematical model of a lathe spindle supported by rolling bearings is newly proposed; the main spindle is expressed by the Timoshenko beam and the rolling bearings are represented by springs and dashpots in radial and momental directions. Comparing with the experimental results, the mathematical model proposed here is found superior to the conventional model. The dynamic characteristics of the spindle-bearing system are simulated by the proposed model. From the calculated results, it is clear that the damping property of the system is dependent on the radial stiffness. Moreover, the damping property of the system is affected by both front and rear bearings.

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This paper deals with the forward stability of a truck crane for lowering the loads. Using a mathematical simulation model developed from the model for the back ward stability in the 1st report, the behavior of a truck crane overturning in the direction of the lifted load in a sudden stop operation during lowering is theoretically analyzes. Effects of crave specifications and constants on the dynamic forward stability are revealed. Thus, an accurate prediction of the stability of a truck crane can be made in the design stage.

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This paper is a continuation to the previous report on the forward stability of a truck crane. The analysis based on a strict simulation model gives precise results but is too complicated for practical use. Here an approximate method using a simplified simulation model is proposed to analyze the behavior of a truck crane overturnings in the direction of the lifted load by sudden stop during load lowering. Thus the minimum acceptable forward stability of a truck crane can be easily determined. Effects of crane specifications and constants on the stability have also been clarified.

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A numerical analysis by the method of characteristics is presented which enables a successful estimation by capsule collision. The pattern of collision for high speed capsules differs from that for low speed ones. Relation between time histories of pressure at fixed points of pipeline and pathes of capsules is discussed.

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