Surface markings in the fast fracture are approximately expressed in equations using both a constant velocity model in which the primary and the secondary crack fronts propagate at each constant velocity where the velocity ratio varies and an acceleration model in which the primary one is assumed to propagates with an acceleration. The results of the latter can accurately predict the surface markings of a point (a small circle), an approximate ellipse and a parabola observed in the engineering plastic plates of the unsaturated polyester resin. The critical distance for the primary crack front first to activate the secondary nucleus and the interference distance for both of crack fronts first to interfere are also determined.

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The stress concentration problem of an elastic circular shaft with one or two circumferential grooves of a semicircular form under torsion is investigated in this paper. The torsion problem of an elastic circular shaft with a groove has been investigated by several authors, but it seems that these results do not always agree with one another. The present results for the problem are in fairly good agreement with Nisitani's results calculated by the so called body force method and Kato's experimental results. There are few investigations on the torsion problem of a shaft with two notches. In this paper, the effects of the distance between two grooves and the radius of semicircular grooves on the stress concentration factors are shown. The method of solution employed here is an application of Green's functions for axisymmetric torsional body force problem of a solid circular cylinder. For this purpose, Green's functions mentioned above are shown.

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Contact stresses between two disks and a sandwiched solid-metal flat gasket are studied to discuss the sealing behavior of the gasket. Assuming that the gasket is an elastic body, the three dimensional theory of elasticity is used to analyse the contact stresses and the deformations in three laminated disks whose both sides are compressed by axisymmetrically distributed loads. By neglecting shearing stresses on the contact surfaces, an exact solution satisfying the remaining boundary conditions is obtained. Numerical calculations are carried out for various rigidities and thicknesses of the disks under various loading conditions. In order to examine the results of the theoretical analysis, the contact stress is measured experimentally by using pressure-sensitive pins attached to a disk. It is confirmed that the theoretical results agree well with the experimental ones except the vicinity of the loaded area.

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The stress concentration problem of a strip with a finite row of circular holes subjected to tension is solved numerically. The number of holes is taken from three to six. 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 with the method of Fourier analysis to satisfy the boundary conditions on the circular edges, and the latter is used with the method of Fourier transform to satisfy the boundary conditions on the rectilinear edges. Stress concentration factors are calculated and are summarized in some diagrams. The results coincide well with the solutions obtained by the finite element method.

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In this investigation, the deformations and stresses in a cylindrical shell under its own weight which is hanging on two wire ropes, are studied by an exact method using a fundamental differential equation for a thin cylindrical shell introduced by one of the authors, K. Mizoguchi. The deformations of a cylindrical pipe without end plates are said to become large. It is therefore discussed about whether it is all right or not to suspend a shell on ropes. Furthermore the problem of a cylindrical shell lifted up at a uniform acceleration is investigated. As a result, it is seen that the deformations of the cross section of a shell are almost invariable in the axial direction, and are different from the beam-like bending deformations.

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Stress strain curves of proportional loading paths under combined axial tension and internal pressure were obtained for aluminium pipe specimens. These curves were unified to a single curve through the equivalent stress and strain defined in this paper. The surface of iso-equivalent-stress loci is considered to be the yield surface, which was verified by some experiments.

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A finite pitch, finite chordlength cascade theory is constructed with elementary wave solutions of an actuatordisk analysis of a three-dimensional unsteady subsonic flow. The theory is applied to the analyses of unsteady forces due to blade vibration or sinusoidal gusts taking into account the effects of spanwise phase shifts of the disturbances. By comparing the fluctuating pressure in the flow passage between the blades with fluctuating lift curves in a complex plane, it is shown that an acoustic resonance in the space between the blades may enlarge lift fluctuation on the blades. Three-dimensionality of the disturbances decreases the lift fluctuation in case of an incompressible flow, but it has the opposite effect if the acoustic resonance occurs.

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A theory for unsteady small perturbations in a shear flow with an arbitrary, but piecewise linear, velocity profile has been developed. Based on this, rotating stall in three dimensional blade rows, subjected to a spanwise sheared inlet flow, is examined. With the total pressure loss characteristics known from experiment, calculations show the effect of flow shear and the spanwise total pressure loss distribution upon various aspects of rotating stall, e.g., the onset condition, the propagation velocity and the distribution of disturbances. The effect of the blade aspect ratio is also discussed.

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This paper presents an experimental study on oblique impingement of two turbulent plane free jets. The effects of impinging angle, impinging position and velocity ratio on the deflection angle and characteristics of a jet after impingement were investigated. As a result of this study, it is found that the deflection angle is in good agreement with the result determined from consideration of total momentums of two jets, and turbulent intensity becomes maximum near the impinging point but it approaches that of a free jet as downstream distance increases, and the index of decay law of maximum velocity in similar profile region increases as impinging angle increases.

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This paper treats the flow around a circular cylinder with a step in a uniform flow. Vortex shedding frequency was measured for various diameter ratios d/D (0 to 1.0), length-diameter ratios L/D (10 to 27) and Reynolds numbers Re (800 to 10⁴). Strouhal number S_t decreases with decreasing d/D and L/D, especially at low Reynolds numbers. The decrease in measured shedding frequency is explained by the effects of the downwash of a free stream from the step. The structure of vortex street was observed by visual means and six hot-wire anemometers. The three-dimensional effects due to the step were studied and Y-shape connection of vortex filaments was found for d/D≥0.8.

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In the preceding reports, a new theory of the multifold series expansion for the steady, laminar boundary layers has been presented. In the theory, a shortly-truncated series solution is always controlled and improved so as to give sufficiently high accuracy at every x-position under any mainstream-velocity distribution, by varying and adjusting the value of an arbitrary parameter which has been specially introduced into the series. This unique theory can be expected to be applicable to a wide range of applied-mathematical fields. The present paper intends to establish a solid foundation for those future extensive applications, namely, (1) to consolidate and complement the new theory, (2) to demonstrate that the mathematical property of the new series is perfect and most excellent in comparison with those of any other different forms of series expansion, and (3) as a demonstrative example, to apply actually the new theory to an exact analysis of the unsteady laminar flow between parallel discs with arbitrarily time-varying gap-width.

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Loss and discharge characteristics and pressure distributions of a flow of polymer solutions through pipe orifices have been investigated experimentally. Three β ratios have been studied, and the measurements have covered both laminar and turbulent regions. The results have revealed how the differences in those characteristics between polymer solutions and water depend on β ratios and Reynolds numbers. In particular, it has been shown that the loss induced by orifices in turbulent region is reduced in polymer solutions compared to that in water. It has also been shown that the ratio of pressure loss to meter pressure differential is almost independent of fluids for high Reynolds numbers. Furthermore, some suggestions have been made on the position of the vena contracta, the coefficient of contraction, the relation to the Toms phenomenon and the loss upstream of the vena contracta.

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The sailwing has various special characteristics due to its flexible structure. In order to estimate a variety of airfoil shape modes and steady state stability of the single membrane sailwing as a representative of the lift characteristics of a sailwing, a systematical method of analysis is present in three different trailing edge conditions. Through calculation examples, various modes of airfoil shapes and the steady state stability of each mode of the sailwing for each trailing edge condition are shown. The relationship between these characteristics and parameters of sailwing taking account of elasticities such as initial tension is also demonstrated. These characteristics are related to an abrupt change in airfoil shape and C_L-α curves of the single membrane sailwings.

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The inertial waves can occur in swirling flows under certain conditions. One of the fundamental phenomena due to the inertial waves is the "elastoid-inertia oscillation" which is a standing-wave oscillation of a fluid in a rotating cylinder. In the experiment reported here, the elastoid-inertia oscillations of several modes are induced as resonant states by a specially designed apparatus. The patterns of the flow field and resonant frequencies are examined by means of visualization techniques. The experimental results are compared with those of the inviscid linear theory. It is found that both the frequencies and flow patterns of the actual elastoid-inertia oscillations can be well estimated by the linear theory.

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An experiment was conducted of wake structure of a stationary capsule in a pipe flow. A reverse flow field behind the capsule due to a large scale vortex extends twice as long as the capsule diameter. Various quantities concerning the turbulence were obtained. As a result, the turbulence in the wake behind the capsule was found quite different from that of an ordinary pipe flow. When the distance between two capsules was less than twice that of the capsule diameter, the effect of the interaction between the two capsules on the drag was observed and the drag on the capsule positioned downstream decreased.

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This paper presents a discharge pulsating pressure (fluidborne noise) generated by a balanced vane pump. It is pointed out first that the pressure pulsation in vane pump includes three types of pressure oscillations, namely, the well known pressure ripple with a fundamental component at vane frequency together with harmonics, the low-frequency pressure oscillation with a fundamental component at rotational frequency of rotor together with harmonics, and the transient high-frequency pressure oscillation occurring with a period of vane frequency. In regard to the pressure ripple, it is pointed out that the experimental values can be explained well, up to about 8th harmonic of it, by the calculated values based on the present mathematical models for flow ripple considering fluid compressibility and pump source impedance. It can be said also that the above-mentioned low-frequency pressure oscillation is caused by the fluctuation in pump leakage flow depending on the rotational position of the pump, and that the transient high-frequency pressure oscillation is caused by the resonance of oil column in the pump discharge chamber including a port adapter.

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The preceding two paper proposed a theoretical formulation of wind penetration and heat transmission through a fabric layer fitting closely to a heated cylinder which is a simple model of clothing system. This paper describes the heat transfer experiments of cylinders covered with 'knicker hose', 'camel underwear', 'body tights' and 'nylon stocking' respectively. The data agree well with the theoretical predictions. Phenomenological features are explained; three regimes of penetration, i.e. front 'flow in' region, middle 'flow out' region, and rear 'stagnate' region. Heat transfer is augmented in the front region, and its behaviour depends primarily on the fabric thickness and the state of contact with the cylinder.

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With reference to the thermal performance of mechanical draft counterflow and crossflow cooling towers, computer calculations are made on the basis of the enthalpy potential theory. Some simplified methods of calculating the number of transfer units are examined and a new correction factor for crossflow towers is obtained in the form of an equation. Representative performance curves, which indicate the variation of the cooling range with inlet wet bulb temperature at constant inlet water temperature and flow rate, are also obtained in due consideration of the available data on the tower characteristics. Then, a simple test method is presented applying the performance curves to the evaluation of test results.

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Applying an alternating electric field to a coaxial-flow jet diffusion flame, the size, structure and concentration of soot particles and the temperature of gas were observed at various positions within the flame. The processes of formation, growth and oxidation of soot particles were examined by comparing the results with those obtained with no electric field applied. Although the peak concentration of soot particles on the flame axis increases as the intensity and frequency of the electric field are raised, the particles are oxidized rapidly due to an increased peak temperature downstream, resulting in a markedly decreased soot emission. The size of soot particles decreases as the intensity and frequency of the electric field are raised.

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Aiming at generalization of the experimental results concerning the effects of an alternating electric field on the processes of formation, growth and oxidation of soot particles reported in the previous paper, comparison between the isokinetic and sonic sampling techniques was made. The effects of an alternating electric field on the processes of soot formation were also compared between a coaxial-flow jet diffusion flame and a premixed flat flame. As a result, the superiority of the sonic sampling technique to the other technique was proved. In addition, the adverse effect of an alternating electric field on the formation of soot nuclei and its favorable effects on the coalescence, aggregation and oxidation of soot particles were reaffirmed.

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The efficiency of supersonic blade cascades for an impulse turbine designed by the conventional methods is not so high as expected because of the boundary layer separation. In this investigation, for improvement of the efficiency of the supersonic blade cascade, some important problems, such as accurate prediction of the starting Mach number and prevention of the boundary layer separation, are discussed based on the measurements and analysis of the flow in the blade passages designed by the free vortex flow method, which is one of the conventional methods. As the result, some design criteria are proposed.

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The aerodynamic effect of combustion in a swirl type combustor was studies using a flow direction detector probe, a Laser Doppler Velocimetry and a Spark Tracing technique. By the flow direction detector, the reverse flow region inside the recirculation zone was found. The velocity distribution was measured by the Laser Doppler Velocimeter and compared with that of without combustion. When the swirl number of the flow was higher than 0.5, the reverse flow zone was increased by the thermal expansion due to the combustion occurring in this zone. The axial velocity in this zone was also increased by combustion. On the contrary, when the swirl number was lower than 0.5, the reverse flow zone was decreased by the combustion. Flow photographs taken for flow visualization by the Spark Tracing technique showed that the small turbulence in the flow was diminished by the combustion.

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A component mode synthesis method is improved for analyzing the vibration of complex structures. The components are not classified into master or branch ones. The interface regions of these components are considered a component named 'interface component', whose displacement is represented with a linear combination of the natural modes calculated from the reduced mass and the reduced stiffness matrices of all other components. The displacements of the interior regions of all components except the interface component are represented with the natural modes of the interface region and the restrained natural modes of these interior regions. The equation of motion of the total structure is translated into a generalized coordinate of these natural modes. Numerical results of the natural frequencies and the natural modes of two specimens are shown.

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Impellers rotate at high speeds, and therefore in order to improve the efficiency of turbomachines it is necessary to take into account not only the static strength to withstand the centrifugal force but also the dynamic strength to withstand vibration in the design stage. In practice various kinds of exciting forces are applied to impellers, but in this investigation a screen with slots around its periphery is positioned in front of the impeller and the impeller is excited aerodynamically through this screen. The resonant vibratory stresses and the pressure distribution are measured simultaneously in resonant condition when the impeller is rotating at high speeds. The relationship between the resonant vibratory stresses and the pressure distribution is discussed in detail by analyzing the frequency variation of the two components.

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In this paper, the effects of the type of chuck and chucking conditions on the stability threshold and on the chatter mark in turning were investigated experimentally. The results obtained are as follows. (1) The type of chuck and chucking conditions have considerable effects on the chatter vibration. (2) The stability limit of chatter vibration represented by the critical overhang length is in good agreement with the result of exciting test on the chuck-workpiece system. (3) The damping ability of the chuck-workpiece system has a large effect on the chatter mark; the magnitude of the chatter mark decreases with an increasing damping of the system.

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As a part of the study on the acoustic/dynamic characteristics of a resilient wheel, the flexural vibrations of the wheel were investigated. At the first stage, the wheel was regarded as a composite circular disk and approximate dynamic characteristics were calculated. At the second stage, the accuracy of the analysis was improved by considering shear deformation and rotatory inertia of the ring type model. Impulse tests for various types of full size wheels were carried out and their dynamic characteristics were examined.

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This report describes the shock absorbing properties of a helmet-head system. An equivalent analysis model of helmet is estimated from the mobility curves which are obtained by experiments. And the changes in the parameters of this model at temperature from -20°C to +40°C are measured. MSC(Maximum Strain Criterion) model is chosen to estimate the damage of the head by an impact. Hence the influence of impact to the helmet-head system, which is formed in these two models, is clarified by simulation. This report also refers to the influence of the helmet's 'peak' when the shock is added to it. The results are as follows: 1) The changes of protection efficiency with varying parameters of helmet model are obtained. 2) The relation between the shock absorbing efficiency of helmet and the impact duration is obtained. 3) The 'peak' has less influence on the head than the wearing condition of the helmet.

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In this paper, the stability of a rigid rotor supported by externally pressurized gas journal bearings with a circular slot restrictor is theoretically determined by the use of the small perturbation method with respect to whirling amplitude. In the theoretical analysis, influences of the inertia forces of the gas film on the dynamic properties of this kind of bearing are investigated and theoretical results are compared with experimental data. Good agreement between the theoretical and experimental results is obtained and it is found that the effects of various factors which affect the stability of a rigid rotor supported by this kind of bearings can be accurately predicted by the present method.

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In this study, a power transmission spur gear is preferably a profile corrected spur gear. Supposing it is allowable that the given value deviates about ten-odd percent from the actual acceleration, it is synthesized how a pressure angle error and a normal pitch error influence the vibration of profile corrected spur gears, using the simulator developed by authors, whose outputs depict precisely the experimental behavious. The influence of these errors is revealed to depend on a rotational speed and a contact ratio as influence degree for each error. The influence degrees are shown on an influence chart of the performance of the rotational vibration by contour lines. A practical equation for the vibration of profile corrected gears having some errors is proposed.

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Many studies on load carrying capacity of gears have been reported. But the influences of tooth profiles upon the limiting load for scoring and frictional loss are not made clear. Experiments were carried out using test gears of module m=3.5 and 4.5 to investigate the influences of tooth profiles upon limiting load for scoring and frictional loss of spur gears. The frictional loss of gears is found not dependent upon the viscosity of lubricating oil. An empirical formula for friction loss was established. This formula was expressed with mean sliding belocity V_gm. Some tendencies are recognized about the limiting load for scoring and they are dependent upon the addendum modification factors. It was found further that the increasing rate of limiting load for scoring caused by ZDTP (additive) is quite dependent upon the tooth profile.

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584Influences of phosphate coating upon the limiting load for scoring of the hypoid gears wee studied using the following gears: (1) Pinions and gear wheels which were both case hardened. (2) Pinions which were only case hardened and gear wheels which were phosphate coated after case hardening. (3) Pinions and gear wheels which were both phosphate coated after case hardening. The limiting loads for scoring of the gears (1), (2), and (3) are quite different from each other. These differences were clarified. Furthermore the limiting loads for scoring of the hypoid gears without phosphate coating were compared with the results of the spur gear test and the disk test.

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Using two kinds of rolling contact fatigue testing machines with high performance, the authors investigated the upper limit of surface durability of a forged phosphor-bronze with a Brinell hardness of 150HB. After many investigations, a new higher pitting limit of 1120 MPa (114 kgf/mm²=0.76 HB) was obtained in the case of pure rolling conditions. when sliding was introduced, the pitting limit decreased by about 20%. The limit stress which can prevent the progressive plastic deformation was nearly equal to the new pitting limit. The flow of metal in the bronze rollers rotated at and near the new pitting limit was examined and compared with that obtained in the case of steel/steel combinations. The upper limit of work-hardening which can be attained in the bronze rollers before occurrence of pitting cracks was estimated using rollers with a few artificial protrusions. The scoring limit in bronze/steel combinations was investigated using a step load method and compared with that obtained in the case of steel/steel combinations. The bronze layer which adhered on steel roller surface after occurrence of scoring was analyzed using an X-ray micro-analyzer, and the effects of hardness of the mating steel-rollers were discussed.

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This paper describes a treatment of machined surfaces in contact in the structural analysis. In order to collect data on the contact stiffness, the relationship between the interface pressure and the surface approach of components subjected to normal forces was experimentally investigated, and then the obtained data were arranged for an easy computational utilization. Using those data, the influence of the contact stiffness on the resulting deformations of structures having joints was investigated by means of a finite element method. From the analysis, it was found that the contact stiffness has great effect of the deformation analysis of components subjected to both normal and tangential forces.

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