This paper describes a new equivalent stress including the principal stress parallel to fatigue cracks based on COD concept and examines the applicability of that stress using a SUS 304 stainless steel at 823 K in air. Also the equivalent strain is derived from that equivalent stress using a continuum theory. Both the equivalent stress and the strain are proved to be good parameters to arrange the low cycle fatigue data in multiaxial stress state.

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In this study, the effect of the Tufftride process to prevent a fracture of cracked steels has been examined. Static tensile strength, rotary, bending and cyclic torsional fatigue strength of steel specimens with pre-cracks were measured after they were Tufftride-processed. The measured values were compared with the strength of non-processed virgin specimens. The results show that the Tufftride process is more effective for fatigue strength than for static strength. For example, in the case of rotary bending, fatigue strength of a specimen with a pre-crack of 1.5mm can be raised to that of virgin specimens by the Tufftride process. The fatigue strength of non-processed specimens with a pre-crack of this size drops to about 63% of that of virgin specimens. It may be concluded that the Tufftride process can be applied to prevent a fatigue fracture of cracked steels.

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In order to predict the performance of a high-staggered low-solidity tandem circular-cascade diffuser of a centrifugal blower, variation of the lift-coefficient due to the mutual interaction between the two cascades is numerically evaluated assuming an inviscid flow. A tandem circular-cascade diffuser is tested at two different circumferential relative positions and the significant influence of the relative position on the lift coefficient is demonstrated. The blade circulation of each cascade is also evaluated from the measured pressure distribution along the blade surface and good agreement with the prediction is demonstrated.

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The effect of acoustically lined walls on cascade flutter is investigated theoretically using a semi-actuator disk model, which permits the considerations for flow turning and total-pressure-loss due to cascades. The three-dimensional flow fields, upstream, inside and downstream of the cascade are solved separately, and then joined properly at the leading edge plane and the trailing edge plane. The acoustic characteristics of walls in each region are specified by the uniform acoustic admittance. It is shown that an acoustically lined wall can stabilize as well as destabilize blade oscillation, depending on its acoustic admittance. The value of wall admittance which is effective for suppressing blade oscillation differs from the one effective for noise reduction. It is therefore suggested that the acoustic lining used for jet engines may work under an off-design condition for stabilizing blade oscillation.

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The three dimensional EHL problem between two elastic rollers with finite width is analized numerically using finite element method and the Newton-Raphson method. The effects of side leakage flow on pressure distribution and fluid film profile are considered and the following results are obtained. (1) Near the center line of roller, pressure distribution and fluid film shapes are resemble to that of the infinite width cae. (2) The maximum pressure appears near the side edge of roller. (3) The minimum film thickness is smaller than that of obtained by infinite width roller model. The convergency is quite severe and the results obtained in this study are limited to several cases. Further numerical calculations are needed to analyze the finite width EHL problem.

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The flow around an inclined flat plate of finite width is studied mainly by the flow visualization techniques for intermediate angles of incidence. At the front surface, any separation of the leading edge does not occure, but the flow yaws towards the side edge and sheds as a side edge vortex. At the back surface, the flow can be characterized by three flows of the side edge vortex, a flow separated near the side edge of the leading edge and a flow separated at the middle of it. The core of the vortex stems from the vortex shed from the neighbourhood of the leading edge, and the vortex extends to the plate center with a decline of its intensity. The flow separated near the side edge of the leading edge is reattached in a short distance by force of the side edge vortex and ;moved towards the plate center. The other separated flow at the middle is disarranged into decay by the side edge vortex and becomes stagnant near the plate surface. These flow characteristics correspond well to the results of the heat transfer behavior.

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Pipes with bend combinations are much used in the heat exchangers, since the curved path in the bends promotes the mixing in flow for active heat transfer. In the present paper, one of the pipes with bend combinations, namely, quasi-coiled pipes composed of many bend elements are investigated, and the relationships between the hydraulic loss and the secondary flow are studied experimentally. The configurations of the cross sections, the bent angles and the curvature ratios of the bend elements of the quasi-coiled pipes are changed in the experiment. The effects of these factors are investigated in detail. As the result, it is found that the secondary flow becomes the type of a one-directional swirling flow in the quasi-coiled pipes if the bend cross sections are changed from circular to rectangular. Moreover, many interesting results are described.

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Experimental results are reported on effects of a wall boundary layer on a flow created by a round turbulent jet injected perpendicularly through a plane wall. The data show that the wall boundary layer contributes to the formation of a swirling flow downstream of the jet together with a predominant negative pressure near the downstream edge of the jet orifice, ; jet spreads are controlled by the wall boundary layer thickness, δ, and ; velocity and total pressure along a jet center-line are expressed as simple functions of δ. A qualitative consideration on the basis of a vortex model of the flow field is also made on a mechnism, which brings about an increase in penetration of the jet into the cross flow with an increasing wall boundary layer thickness.

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This paper presents a new method of calculation for designing a supersonic nozzle and the experimental results. In the present method, calculation is started from the convergent part of the nozzle where the flowfield is subsonic and the boundary condition of downstream side can explicitly be given by considering a sonic line which is determined by using a new method which we have developed. The sonic line, as it is, can also be available as the initial value for the calculation of supersonic flowfield. The calculated results have been compared with experimental ones and a good agreement between them has been recognized. Furthermore, by using the present method, we have checked Hall's analytical result and Riise's assumption.

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This experimental study concerns falling water films on a vertical cylinder to which a ring with a square cross section of 1.5 mm×1.5 mm is attached. Using the electric capacitance technique, some characteristics of surface waves of water film were measured near the ring under the same conditions as in the previous experiment in which the film thicknesses were measured by a needle contact method. When the ring was in the non-equilibrium flow region, the predominant frequency of waves f_max increased just downstream of the ring and then gradually decreased. When the ring was in the equilibrium flow with disturbance waves, little difference was found in f_max upstream and downstream of the ring. Wave velocity was not considerably influenced by flowing over the ring. The effect of the probe diameter on accuracy of the capacitance technique was theoretically discussed by assuming two-dimensional sinusoidal waves.

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As a new one of the line elements employed to control and suppress wave transmission in hydraulic lines, the coaxial 'double' pipe is treated in the present report. The equation for a viscous wave flow between two cylindrical walls of different radii with the same axis is solved. for the case of periodical waves, the complicated solutions including many-valued complex Bessel functions of the 2nd kind are rigorously computed and conveniently approximated as well. In terms of wave transmission there exists an equivalent single pipe which well simulates the properties of a double pipe. Frequency response tests were successfully carried out in actual oil-hydraulic double pipes to verify the validity of the analysis. The experiment reveals that the wall elasticity works to reduce the velocity of sound much more in double pipes than in single ones.

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An expansion of moist air or steam in a supersonic nozzle gives rise to nonequilibrium condensation phenomenon, and a condensation shock wave appears in the supersonic section of the nozzle. In the present paper, a condensation shock wave was observed optically by a method in the case of moist air expanding in a supersonic nozzle, and the effect of the relative humidity of moist air on the shape of a condensation shock wave was discussed. Furthermore, a flow of moist air expanding in a supersonic nozzle was analyzed by the method of characteristics. Based on these experimental and calculated results, the mechanism of formation of a condensation shock wave was clarified.

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The analytical method for predicting the flow characteristics at the outlet of centrifugal impellers is presented taking into account the influence of velocity distortion in both the peripheral and the hub-to-shroud directions and its effectiveness was confirmed with the flow measurements around pump impellers. The results show that the increase of wall friction due to a mixing of flow just after the impeller exit should be adequately considered for successful prediction, and the influence of velocity distortion in the hub-to-shroud direction should also be considered for the case of the parallel-walled diffuser width being larger than the impeller exit width, while it is negligible in the case of the diffuser width being equal to the latter. It is pointed out that the peripheral velocity component of the outlet flow used for the determination of slip factor and the theoretical head should be defined by the mass-averaged value of the section.

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Pump casing stress caused by external piping forces and moments in addition to internal pressure was investigated. The test pump type was a axially split, single-stage double-suction volute with foot support. A stress analysis by FEN(MSC/NASTRAN) was first performed, after a FEM model had been accurately constructed applying a CAD system. Then, actual external piping loads were applied to four test pumps and casing stress was measured with strain gauges. Good agreement between analyzed and measured results of casing stress was obtained. When plural loading were applied, it was found that the magnitude of the loads but also by their direction. When nozzle loads based on API 610-6th standard were applied in addition to internal pressure, the highest stress was observed on the nozzle surface in the vicinity of the foot connection, and the magnitude of this stress was rather great. One of the conclusions from this study was that sufficient consideration must be made for casing stress caused by API loads, especially in the case of low pressure pumps.

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The nozzle of a cross-flow turbine has to give a certain circumferential velocity and an optimum angle to the flow at the nozzle exit (runner inlet). Therefore, the nozzle shape has an important influence upon the turbine performance. Its shape is asymmetric and complicated, and the exit flow from it has free boundaries. The flow from such a nozzle has not been analyzed enough until now because of complexity of its flow. In this report, the flow from a nozzle with arbitrary asymmetric curved surfaces is calculated numerically by Schwarz-Christoffel method. In order to estimate the accuracy of this method, the calculation results of the flow from a cross-flow turbine nozzle are compared with experimental ones. Furthermore, the effects of nozzle shape on the exit flow are investigated.

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In order to clarify the influence of blade camber ratio on the effect of surface roughness on axial flow fan performances, three rotor blades with different camber ratios have been designed to the same fan specification, and performance tests have been conducted by changing sand grain roughness of blade surface. The axial fan rotor with a larger camber ratio indicates greater deterioration of performance with an increasing surface roughness. In the case of small camber ratio, the torque coefficient of the fan does not change with roughness. Also the effect of blade surface roughness has been investigated from the viewpoint of boundary layer theory.

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In a large free forging press, the high speed operation of a directional control valve often causes an oil column separation in the return line just after the valve. The process of oil column separation from the start of valve operation to the contact of oil columns is analyzed by the numerical calculation, and the relation between the valve closing time of linear closing mode and the surge pressure due to the contact of the oil columns is obtained. The expression of flow characteristic of the valve can be simplified by use of an effective stroke of the valve. The general relations between the oil column separation caused by the linear mode closing of the valve and the dimensionless parameters which describe the characteristic of pipe system are obtained.

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The viscosity of pure 2, 2, 2 trifluoroethanol and its aqueous solutions of 85 mol% and 60 mol% has been measured in the temperature range 273 - 453 K and at pressures up to 40 MPa by a closed circuit capillary viscometer. No experimental data are reported for the pressure dependence of the viscosity of these mixtures so far. The experimental error of the present measurement is estimated at ±1.1%. The measured data were correlated with an equation of the viscosity in terms of temperature and pressure for each mixture. At atmospheric pressure, additional measurements were performed with the aid of a Ubbelohde viscometer over the whole range of composition was confirmed.

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Development of the new engineering materials such as ceramics, amorphous semiconductors, synthetic polymers, extreme-low and high temperature resisting materials, etc. has made it more and more important to analyze the unsteady non-linear heat conduction problems concerning these materials. This paper deals with two cases of one-dimensional exponential models of x=constant: (1) λand cρ are functions of coordinate x (model A) and (2) λand cρare functions of temperature T (model B). The transient features of heat transfer for both models have been mathematically analyzed and numerically calculated according to exact solutions.

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A new type impact damper consists of a bed of granular materials moving in a container fixed to the primary vibrating system. The problem is to determine the characteristics of the damper with granular materials, for reducing the vibration of a single degree-of-freedom system when the driving force is simple harmonic. This report treats the case when the bed in the container impacts on both end walls in a vertical oscillation of the system. Experimental models were tested in the laboratory and analyses were made to find steady state periodic solutions of the system. Results of analyses agreed favorably with those of experimental tests.

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Phenomena on the interaction between self-excited and parametric vibrations in the flow-induced vibration problems are described by a differential equation of Van der Pol - Mathieu type with the non-linear restoring force as a mathematical model. Periodic solutions in the regions of parametric resonances of the first and the second orders are approximated by the sum of two frequency components. These approximated solutions have high accuracy. The stability criterion of periodic solutions established by approximately obtaining the regions of instability in Hill's equation for small disturbances from periodic solutions.

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In order to eliminate the ground vibration as pollution, this paper presents a systematic design procedure of the active force control system proposed in the previous papers. First, from the viewpoint of feedback control, the active force control system with a series-type dynamic compensator is constructed. Secondly, with the aid of the parameter optimization technique, the necessary conditions for optimality of the system are derived. Thirdly, for the purpose of solving the conditions described by the nonlinear matrix equations, an iterative algorithm based upon the quasi-Newton method is proposed. Fourthly, by using the design procedure, the active force control system is designed. Finally, the characteristics of the system are discussed and the effectiveness of suppressing the exciting force is compared with the result of the feedforward control method gained in the previous papers.

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A magnetic disk drive is excited by an actuator force and a disk driving force. It is shown that vibration reduction results when the actuator force is applied to the rotary access mechanism. A vibration analysis utilizing a building block approach confirms that the carriage assembly structure contributes largely to the vibration characteristics of the access mechanism. The bending resonant frequency in the seek direction is detrimental to high accuracy and high speed head positionings. The relation between the structural stiffness of each element and its vibration characteristics is clarified. High rigidity elements which comprise the carriage assembly structure are investigated and comparative studies on two types of head supporting gimballs are carried out.

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This paper deals with an axial vibration of a horizontal rotor which is driven through a single craw type gear coupling under no load operating conditions. The effects of coupling misalignment on the vibration are experimentally investigated. Under good alignment conditions, remarkable axial vibrations with large amplitude and long period (in some cases 3mm in amplitude and 3sec. in period) were observed in certain narrow speed ranges. The period, which almost coincides with that of beat of the torsional vibration of a rotor, becomes larger with an increase in amplitude. When a large angular misalignment exists, the rotor axial vibration is not likely to occur. In order to illustrate the mechanisms of the axial vibration, three models are proposed on the basis of experimental results.

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A planet gear with thin rim, which has a small radial clearance between the rim and the gear shaft, is chosen as the subject of study. The stress distribution in the planet gear is analyzed by the photoelastic method and the following results are obtained: Fillet stresses are not proportional to the tooth load and they vary with the radial clearance even if the tooth load is constant. Both the position and the magnitude of the maximum stress occurring in the planet gear vary with both the tooth load and the radial clearance. Furthermore if the ratio of the radial clearance to the tooth load is constant, fillet stresses in the planet gear are proportional to either the radial clearance or the tooth load.

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A lot of investigations have been made on the friction between gear teeth, but most of them discuss its coefficient and few do its vibrational characteristics. As an element in a vibrational system, the friction has two aspects, that is exciting source and damping. In this paper, its vibrational characteristics are discussed. The results obtained in this study are: (1) The peak value of vibrational amplitude response curve caused by the friction, where main component of the vibration is synchronized with meshing frequency, is almost independent of lubricating oil viscosity and transmitting power. (2) Its effect as damping element to forced vibration depends on the kind of exciting source.

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In the no lubricant operation, it is believed that a stainless steel gear, a brass gear and a cast iron gear are better applicable as the mating gears of nylon gears for rust prevention, than a carbon steel gear. But the abrasion of nylon gear when the nylon gear meshes with these gears is not clear, because these gears have been little used. In this report an abrasion experiment of nylon gear, which meshed with these three metallic gears, was performed. And the abrasion of nylon gear in this experiment was compared and examined with the abrasion of nylon gear in the earlier report, which meshed with the carbon steel gear. The abrasion of nylon gear when the nylon gear meshed with three different materials gears has been made clear.

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It was confirmed that the endurance limit of power transmission nylon gear can be correlated with Tc·(T/b)[Tc: contact period of tooth of nylon gear, T: torque acting on nylon gear, b: face width], and an equation for predicting the endurance limit was offered. And the damage forms of nylon gears for power transmission were classified and each damage state was clarified. Each area of damage was shown too.

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About 36 kinds of spatial four-bar function-generating mechanism with a single degree of freedom between the drivers and followers, a systematic displacement analysis in consideration of clearances and tolerances has been carried out using four kinds of transformation functions and their derivatives with respect to kinematic parameters. Moreover, applying this method of analysis to a planar four-bar mechanism with offsets and clearances, the relations between planar mechanisms and spatial mechanisms have been discussed about the output errors.

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This paper presents a process of obtaining a leadscrew of higher lead accuracy in thread grinding. Leadscrews used for machine tools or length measuring machines often act as a standard scale for table positioning. They are ground after hardening. With the development of NC machine tools, they are required to have high level precision. This paper describes an improvement of the control system of the closed loop compensation device in the thread grinder. Thanks to the improvement a high pitch leadscrew of 800 mm in length can be obtained with a cumulative pitch error of 2.4 μm and a drunkenness of 2.0 μm. Furthermore, the causes of pitch error and drunkenness remaining after grinding are discussed.

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In order to accomplish the automation of machining process completely, chips must be continuously conveyed from machine tools to the disposal system by mechanical and fluidic methods. The latter method is more suitable for conveying chips produced under wet condition than with the former, but the mechanism of conveying chips through a horizontal pipe has not yet been clarified. Therefore, in this study the mechanism of hydraulic conveying of chips has been experimentally analyzed. From the results, it was found that the drag coefficient of conveying chips estimated with the representative area, obtained from the number of chips per unit volume, and maximum relative velocity is nearly constant within a range of Reynolds numbers from 20 to 10000. In addition, it was revealed that the maximum velocity for conveying chips through the pipe can be approximately estimated by using the void ratio and the number of chips per unit volume.

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