The macroscopic criterion for brittle fracture under compressive stresses, namely mode II fracture criterion, was substantiated by several tests such as tensile test, compressive test, splitting test, mode I and mode II fracture toughness tests and compressive test under hydrostatic pressure. Rocks, graphites and mortars were used for these tests. Also, we showed that splitting fracture is a mode II fracture, and that Youngs modulus is proportinal to the amount of the crack restraint under uniaxial compression, which is a stress difference between the applied stress at crack initiation and that at final fracture.

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In the present paper, the three-dimensional stress analysis of a rectangular cantilever thick plate subjected to a uniformly distributed load on the semicircular area of the upper surface is carried out using an extended Love's moderately thick plate theory proposed by one of the authors. From the results of numerical calculations, the three-dimensional stress states in a rectangular cantilever thick plate are clarified and it is found that the distribution of longitudinal normal stresses is nearly linear, and that of shear stresses is almost parabolic in the case of the ratio of thickness to width of the plate being less than 0.1.

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The authors study an elasto/visco-plastic dynamic response of thin shells to strong blast loads, where a consideration is given to the viscosity of the material in the plastic range. The equations of motion and the relations between the strain and the displacement are derived from the Sanders nonlinear theory for thin shells. The constitutive relation for shell response is linear elastic, visco-plastic. In the linear elastic range Hooke's law is used. In the plastic range the elasto/visco-plastic equations by Fyfe based on the model developed by Perzyna are employed. The criterion for yielding used in this analysis is the von Mises yield theory. The fundamental equations are numerically solved by a method using finite difference in both space and time. As a numerical example an elliptical, cylindrical shell subjected to external impulsive loads is analyzed.

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Some kinds of design methods of supersonic impulse turbine blade cascades have been already published. However, many problems have remained unsolved concerning the performance of the cascades designed by such methods because of the lack of systematic test data. In this investigation, two-dimensional cascade tests were carried out on four kinds of cascades designed by use of supersonic vortex flow, each of which has different turning angle and inlet Mach number at design condition. As the result, the general characteristics of these cascades, such as the variation of performance with inlet Mach number and back pressure and the correlation between the performance and turning angle or inlet Mach number at design condition, have been clarified.

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When wet air or steam expands rapidly, condensation occurs at a supersaturated state rather than at its equilibrium saturated state. Many studies were reported in regard to this phenomenon so far. Unfortunately, however, most of these investigations were done on supersonic flows, and in the case of a subsonic flow there are many questions which are not yet resolved, especially about the effects of condensation on the flow-field. In the present study the condensation phenomena of water vapor have been experimentally investigated for an unsteady subsonic flow induced in a driver section of a shock tube. As the result, the relation between condensation and thermal choking of flow due to heat release of the latent heat of water vapor has been clarified. When the flow is choked thermally, a shock wave is generated and propagates upstream. Assuming a simple flow model, the Mach number of the propagating shock wave has been calculated. At the end of the present paper, the thermally choked flow due to condensation has been discussed from a viewpoint of analogy with a detonation wave.

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The characteristics of an air flow around a sphere were investigated by means of the measurement of drag and pressure distribution and by the surface oil-flow method in the Reynolds number range from 10⁵ to 4×10⁵. A hysteresis loop was found in the drag coefficient - Re curve and also in the pressure coefficient - Re curve at the critical Reynolds number range between 2.1×10⁵ and 2.5 ×10⁵. In the present paper, the irreversible process of hysteresis was examined in this critical Reynolds number range. The experiments were carried out under steady flow in a wind tunnel of Gottingen type, the turbulence intensity being 0.5 percent.

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In order to examine the diffusion of a slightly heated jet on a plane wall, intermittency factors, crossing frequencies, conditional zone averages, power spectrum densities and probability densities of velocity and temperature as a passive scalar were evaluated by digital processing of instantaneous temperature and three velocity components. The intermittency factor distributions indicate that intermittent regions extend more in sparwise direction than in normal direction. This presumably results in a larger entrainment from sparwise edges and explains the cause of anisotropic growth of the three-dimensional wall jet observed in the 1st report. Turbulent zone averages of velocity and temperature are larger than those in non-trubulent zones. Probability densities of velocity and temperature have only one peak and their spectra have no spike in far field from the jet exit. Flow field is characterized by rather random and three dimensional turbulence. These results are confirmed by flow visualization of cross sections normal to jet axis.

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One of the authors reported on the analysis for the oscillation of a jet attaching to an offset parallel plate, caused by the infinitesimal periodic fluctuation of bubble pressure. This paper presents the influence of the geometry of flow passage, especially an opposite wall, on a jet attaching to the side wall and switching phenomenon of the jet caused by traversing the opposite wall quasi-statically. Some of the conclusions are as follows. (1) Flow patterns can be classified into two types depending on the geometry of flow passage. (2) An analysis for an attached jet which is influenced by an opposite wall was carried out. The analytical results are in good agreement with the experimental ones. (3) Attachment and detachment of the jet show a hysteresis phenomenon when the offset distance of the side wall is varied quasi-statically.

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Both the finite difference method (FDM) and the finite element method (FEM) treating the Navier-Stokes equation (NS) and the equation of continuity (EC) are generally used for the numerical analysis of viscous flows. In this paper we propose a new FEM without the NS and the EC for steady viscous flows. The formulation of the FEM is based on a hybrid type of the virtual work principle used in solid mechanics. To investigate the validity of the present FEM, we calculate a two-dimensional cavity flow. The results calculated by the FEM agree well with those by the FDM. A merit of the FEM makes it easy to treat boundary conditions that the quantities on the boundary are hydrodynamic ones such as velocity and/or pressure.

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This paper mathematically analyzes the flow structure and convective nonlinearity in the 'end correction' problem. The Laplace equation of the velocity potential is rigorously solved for a boundary geometry formed by a plane wall and a circular aperture in it. Applying three different kinds of flow conditions over the aperture to the solution, we obtain three different values of end correction and functional expressions for the potential and velocities. One of those end corrections proves to be larger than (8/3π)α(α ; radius of aperture) which Rayleigh has regarded as the upper limit. The distribution patterns of the potential and velocities in the flow are shown in diagrams. Moreover the Bernoulli equation gives the pressure and makes it possible to theoretically estimate the convective nonlinearity caused by the kinetic energy. The effects of hamonic wave-distortion on the end correction impedance due to this nonlinearity are also discussed.

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Theoretical estimation of viscous loss in the 'end correction' problem remains unsolved. Stewart or Sivian has applied to this purpose Rayleigh's imaginary correction tube originally proposed to explain fluid inertia effects. However such a hypothesis is expedient and groundless. This paper intends to theoretically analyze an oscillatory viscous flow around a circular aperture in a plane wall. By assuming concentrically hemispherical equipressure surfaces around an aperture, the flow is mathematically solved. The resulting flow model reasonably simulates the unsteady boundary layer on a wall, and gives a resistive end correction one-fourth as small as the resistance of an imaginary tube. It is pointed out that a large value of the non-dimensional frequency α√(ω/ν) deteriorates the accuracy of resistance measurement. The former experiments lack in this necessary precaution. Presumably that is why the experimental results by Sivian or others seem to support the questionable hypothesis.

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Step response of a hydraulic servomechanism under inertial loading is studied. Conclusions obtained from this study are summerised as follows : (1) If the hydraulic servomechanism is geometrically symmetric, free from external leakage, and if compressibility of oil is constant, then nondimensional pressures in cylinder chambers satisfy the relation P₁+P₂=1. This relation is lost when a cavitation appears in one of the cylinder chambers. (2) The stability becomes inferior with smaller bulk modulus and larger inertial load. (3) The stability becomes superior with internal leakage and viscous and/or Coulomb friction. (4) Asymmetricity A₁≠A₂ causes asymmetric response depending on input direction. (5) The step response is influenced significsntly by air bubbles dispersed in the oil. Effective compressibility of the oil is reduced by the air bubbles. The form of basic equations used today to study the hydraulic servomechanism is conserved in spite of presence of the air bubbles if the tangential bulk modulus is used.

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Infrared reflectivities and emissivities of nickel, cobalt and chromium are measured at high temperatures. Cobalt is found to have a remarkable hysteresis of emissivity around the martensitic transformation temperature. An optical dispersion equation is applied to describe the spectral characteristics of interband transitions and conduction absorption of electrons of these three metals. Quantitative expressions for the parameters in the equation are obtained for temperatures up to 1700, 1400 and 1000 K for nickel, cobalt and chromium, respectively. Spectral and total emissivities are calculated as functions of temperature and crystal phase.

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The paper describes a practical and precise analysis which concerns the matching between diesel engine and turbo-supercharger. The exhaust piping system of an actual turbocharged 4-cycle 6-cylinder diesel engine including engine cylinders and a turbine is calculated by applying the method of characteristics under the boundary conditions as exactly as possible. Since the computation at the pipe junction is extremely complex and tedious, a practical and reasonable simplification has been proposed, which accomplishes a considerable shortening of the computer time. The results of the calculation have generally agreed with the experimental measurements. The factors which influence the magnitude of the available exhaust gas energy are examined and the optimum dimensions of exhaust piping systems for the maximum energy utilization are suggested.

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This paper proposes a measuring system for determining the current position and/or heading of a ground vehicle. The system is made up of digital speed pick-ups (tire revolution counters) set on both sides of the vehicle, a self-contained computing processor and an X-Y recorder. The self-contained processor computes the location and heading of the vehicle using only the speed data of both sides of the vehicle and also presents the location data on the X-Y recorder within very short period. The experimental vehicle is a tri-cycle battery car with rubber tires. Reduction of induced errors has been performed by measuring the centrifugal acceleration of a turning vehicle and sensing the azimuth reference line drawn on the road. The trajectory of the vehice has been successfully displayed by the experimental system implemented. The system can be applied to determining the position and heading for automatic vehicle monitoring and automatic guidance of ground vehicles.

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Frictional noises which occur when a steel rod is pressed in the radial direction on a rotating thick steel disk with various random surfaces without lubrication are studied experimentally and theoretically. When the surface roughness becomes larger, loss of contact occurs. The results calculated by considering the random surface roughness as an external force agree with the experimental results. Assuming a rod as a sound radiator of cylindrical waves, the calculated conversion ratio from acceleration of a rod to sound pressure is coincident with the experimental results. Additionally, sound pressure level is proportional to the differentiation of lateral acceleration of the rod. This conversion ratio makes it possible to predict the sound pressure level from the easily measured acceleration.

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Usually the faults on the gear surface are noticed by a change in characteristics of gear sound. But it has been difficult to discriminate the symptoms on the surface of gear teeth using the sound of gears in operation. Authors suggested that the information about the surface failure might be obtainable by observing the frequency fluctuation of gear sound, and made a measuring system based on this information. In this paper the pitting tests are performed and the sounds of gears are measured at several numbers of load cycles. The scoring tests are also performed. The changes of the frequency fluctuation of gear sounds are introduced according to the failure growing. As a conclusion it can be said that the results by this new analyzing method revealed that a lot of information could be obtained about running conditions of gears, and that it is possible to open up a new field in detecting the gear surface failure.

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Squeeze casting increases the productivity of the fabrication of composite materials, whereas the theoretically expected strength is not easily attainable by it due to many factors. The present investigation has been carried out systematically to find the optimum conditions for squeeze casting applied to fabrication of SiC fiber reinforced aluminium. From the experiment, it is found that the selected conditions satisfy the requirements, i.e., soundness and high strength. The results obtained are summarized as follows : l) Squeeze pressure must exceed 500 kg/cm² to produce composites free from cavities. 2) Infiltration speed does not affect the microstructures and tensile strength. 3) There exists a suitable temperature range to fabricate reliably sound composite materials with a given volume fraction of fiber. The range can be presented by considering a parameter depending on both temperatures of fiber and molten aluminium immediately before infiltration.

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A new cold forming process of a hollow article with flange is developed. In this process, a special flow of the material for recess formation, which appears at the final stage of the conventional extrusion process, is promoted by applying an auxiliary mandrel load. This process has features of efficiency of production, high quality of the product and lower working load as compared with the conventional process. Further, this process is improved into a more efficient and easy process through the adoption of an idea to punch the hollow top of the product in the same working stroke. This punching achieves a precision shearing and a smooth sheared surface is obtained. Moreover, the punching die is useful to determine the product height and suppress the necking at hollow wall which limits the applicable mandrel load. So, the process becomes much easier to practice and an application to an actual gear blank with boss is possible.

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The theoretical stability characteristics of a rotating elastic shaft are investigated. For a symmetrical rotating shaft model, in which the shaft with a rotor at its midpoint is supported by journal bearings, the limit frequency at which oil whirl of conical mode starts (for both elastic and rigid shafts) can be analyically obtained in addition to the critical conditions which are absolutely stable against that mode of oil whip. A stability chart for the translational mode based on infinitely short bearing approximations and Gumbel's boundary condition is also presented.

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