In this paper, using a differential equation introduced by one of the authors, the behaviors of a cylindrical shell with periodic circular cut-outs under uniform external bending are analyzed, and the deformation, stress distributions and the flexural rigidity of the shell regarded as a beam are discussed. The method of analysis proposed in this paper has no restrictions with respect to the shape, size and the number of cut-outs. As the cut outs get closer to each other, the distribution of the radial displacements near the cut-out shows a complicated character under the influence of the cut-out. On the other hand, the value of stress concentration factor at a middle cross section and the flexural rigidity of the perforated shell are reduced.

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In this paper, impact fracture behavior of circular disks, which are made of whetstone or plaster, is discussed experimentally. The fracture phenomena of a disk being dropped on to a rigid plate are photographed for many disks which have various values of ratio a/b (a is the inner radius and b is the outer one.) From these pictures, the cracks appearing in the disks are classified in to several patterns. Next, the stresses developed in the impacted disk are visualized by using the dynamic photoelastic technique. By observing the maximum tensile-stress at the inside or outside surface of the disk, the fracture mechanism of the brittle disks can be estimated.

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As the means for measuring the surface contour of a three-dimensional uneven object by the moire method are known the oblique shadow method using collimated light beams and the modified method utilizing divergent light rays emanated from a point light source. The former method facilitates the accurate measurement of the surface contour of a measuring object. On the contrary, the latter method gives an approximate surface contour. In spite of the above mentioned drawback, the latter method has been used widely for the measurement of the surface contour of a large uneven object up to this day. In this paper, an accurate theory for the latter method is proposed. Also a procedure for determining the applicable limit of the latter method is presented.

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In the cases that an impulsive load (impulsive longitudinal load, impulsive shearing load or impulsive bending load) is applied, the stresses and the strains induced in an infinite elliptic bar are obtained. The analysis is based on the fundamental equations of three -dimensional elasticity. Laplace transform and Fourier transform techniques are utilized for the analysis. The inverse transforms are carried out under the following two assumptions ; (1) The eccentricity of the elliptic cross section is small. (2) After the application of the impulsive load, the elapsed time is not very short. The results obtained from the analysis are compared with the results of a circular bar.

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In order to prevent noise generated from torsional resonance of multiblade fan, motor-driven by thyristor speed controller, the authors analyzed torsional natural vibration and frequency response of the fan shaft system, and elucidated the key points in design for vibration reduction. In analysis, it was assumed that the blades were beams, and the vibration system was a linear and branch shaft system, and transfer matrix method was used. For frequency response analysis, especially, material damping of each part of the system and damping due to solid friction of the bearings were considered. With regard to the validity of analysis, the experimental proof was done.

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Most of the servo valves taken up for research previously were pressure control valves which control a hydraulic pressure linear to input current and allow a vent flow. No research exists on the servo valves which are able to control hydraulic pressure linear to input current at near zero flow rate without a vent flow. This report describes thet establishment of a design method by theory and experiments utilizing pressure control servo valves experimentally manufactured which are able to obtain hydraulic pressure linear to input current independently of flow rate.

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A method for solving the analytical problem of a cascade in a distorted and oscillating periodic flow is developed here by using the finite element method. The vorticities in an unsteady inviscid rotational flow were calculated by a convective-difference scheme. The outlet flow angle was corrected by successive iteration taking into account the Kutta condition, whereas the strength of shedding vortices was determined from one-valued pressure condition. The fluid-dynamic forces acting on the blade are expressed in line integral forms in the upstream and downstream regions. The present method is applicable to the analysis of a cascade with arbitrary blade profile in a periodic waved flow with large disturbances. However it is limited to the case of wave-length equal to the pitch of cascade. An example of the flow through a cascade composed of segmented circles was solved for an upstream absolute flow with the same direction and varying in the sinusoidal travelling wave. The pertinent streamlines, equi-vorticity lines and the time-variation of the lift and drag are shown in the paper.

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An analysis is made of pulsating laminar flow in a sinusoidally curved pipe. When there exists no steady flow, the axial velocity is larger in the inner part than in the outer portion of the pipe section. Steady flow makes the adaptation of secondary flow to the change in curvature of the pipe axis delay. When the value of the parameter k=√(ω*/ν*)r₀* is small, the degree of delay is similar to that for steady flow and is almost independent of time; but it becomes very different from the steady case and varies with time as the value of k increases.

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The turbulence characteristics of a coaxial round jet are studied experimentally. Measurement is made of the turbulence intensities and Reynolds shear stress for various excess-velocity ratios. The investigation is performed considering that the character of the jet varies towards downstream. It is found that the self-preservation does not apply for this flow field. The turbulence structure varies gradually with a progressing homogeneity of the intensity to the downstream and approaches asymptotically to an axisymmetric wake. The process of variation depends strongly on the initial condition and on the local excess-velocity ratio. Experimental results confirm the theoretical assumption which the authors made in the previous paper.

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Based on stability criterion, many researchers are investigating the lower critical Reynolds number of non-Newtonian fluid flow in tubes. The authors estimate theoretically the lower critical Reynolds number of Newtonian fluid flow in concentric annuli and in parallel plates and non-Newtonian fluid flow in circular pipes by the use of the stability parameter. The theoretical results of the present investigation are compared with the theoretical results given by Hanks, Mishra and Ryan and the experimental results quoted from literature. It is found that the theoretical lower critical Reynolds number agrees well with the experimental results of non-Newtonian fluid flow in circular pipes and also agrees with the experimental results of Newtonian fluid flow in concentric annuli and in parallel plates within the errors of the experimental values.

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The flow of polymer solutions form a reservoir through a capillary to air is experimentally investigated. The flow patterns in a reservoir, the axial pressure distributions in a capillary, and pressure fluctuations in both the capillary and the reservoir are measured. Then, the influence of the flow pattern in the reservoir on the pressure loss in a capillary and on the instability of the extruded jet are discussed. It was found that the pressure loss in the case of an unstable flow was larger than that in the case of an stable flow. And the onset of the unstable flow is discussed.

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Experimental investigations have been made of the forced-convection heat-transfer for a fully developed laminar flow in horizontal circular tubes and concentric annuli in order to clarify quantitatively the effect of natural convection on their heat-transfer characteristics. When the Grashof number Gr=βgLrTr/Ur², defined using Tr=WGLr²/α, Lr=(d²₂-d²₁)(q₁+q₂)/(d₁q₁+d₂q₂), Ur= ν/Lr as the characteristic temperature, length, and velocity, respectively, is introduced, the heat-transfer characteristics of the secondary flows induced by natural convection can be expressed by the following equations; for inner tubes, Nui=0.44Gr^0.20Pr^0.28(d₂/d₁)^0.35 for outer tubes, Nuo=0.38Gr^0.20Pr^0.28 These two equations are applicable to circular tubes and annuli, regardless of heating amounts of inner and outer tubes.

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Effects of a flow obstacle are examined on the film thickness in gas-liquid two-phase upward flow belonging to slug, froth and annular flow regimes. In this experiment, a ring type obstacle is employed as the obstacle, and time varying holdup is measured by means of the constant electric current method at eight cross sections near the obstacle. Discussions are made mainly on the minimum film thickness determined by the measured holdup. Whether the obstacle is inserted or not makes essential difference in the process of changing film thickness. Values of minimum film thickness for the upstream zone of the obstacle take minima at rather small air velocities and are reduced to approximately a tenth as large as those without obstacle. Minimum film thickness in the downstream zone decreases monotonously with air velocity.

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An additional experiment was made of the effects of flow obstacle on minimum film thickness in gas-liquid two-phase upward flow. The obstacle used in this experiment consists of four rectangular shaped pieces jutting from the inner surface of the tube. The results suggest that the present type of obstacle also has strong effects on the film thinning process upstream of the obstacle, which are similar to those of the circular ring used as the obstacle in the 1st report. However, because the liquid film can flow between the pieces, a reverse flow across the obstacle is easy to occur during the drainage period existing at low air velocities, and the amount of liquid accumulated below the obstacle at relatively high air velocities is reduced. On account of these effects, the minimum film thickness upstream of the obstacle increases at low air velocities and decreases at high air velocities. On the other hand, the minimum film thickness in the downstream region is almost the same as that without obstacle.

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The authors have studied about a liquid atomization by the impinging of two jets. In this paper, the film formation by jets with low velocity is treated. The relations between the properties of jets, i. e. the velocity, the impinging angle, the thickness and velocity distributions on a film, the size and the shape, are made clear by the experiments and compared with the calculated results. A particle track method for the velocity measurement, an interference method for the thickness measurement and a microflushed photograph for the size and shape of film have been used. By considering that the disintegration is caused by the relation between inertia force and surface tension at the edge of film, the size of film at the surface angle α is expressed as R_α=1/2 p/σ V_1α² K_α sin²δ_α The velocity distribution of jet has influences on the formed film. The minimum thickness at the same surface angle is proportional to the surface tension and inversely so to the density and the square of velocity of the film.

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The authors investigated the effect of surface roughness of 0.45 % carbon steel on scoring in rolling/sliding contact under starved lubricating condition using a two-disc machine. The scoring resistance of carbon steel was significantly affected by the extent of work-hardening of disc surfaces and formation of the surface films during running-in. The disc with small surface roughness which was little increased in scoring resistance during running-in had a tendency to suffer scoring even under mild condition. Therefore, the intensity of the scoring resistance of the disc with small surface roughness showed duality, that is, scoring occurred under extremely mild condition, or under extremely severe condition depending on the formation of surface films and the work-hardening. On the other hand, the disc with rough surface was work-hardened and the surface films were formed on its surface. Therefore, its scoring resistance was high.

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A new type of cutter "Revolving type pinion cutter" for the hobbing of the face gear has been developed in consideration of facility of manufacturing. The form of the cutter has been analysed and the calculations have been done to show the effect of various form factors on the cutter accuracy. The result shows that the cutter can be used for the hobbing of the face gear. A cutter has been made practically giving all the details of various steps necessary to make it. Face gear has been hobbed by fixing it in the hobbing machine. The form of the cutter has been confirmed by taking the tooth bearing of the generated face gear in actual mesh. It is proposed that the revolving type pinion cutter be used for the hobbing of the face gear for better productivity and economy.

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The hobbing theory of generating the involute gear teeth has been often reported. However, a hobbing mechanism of enlarging the unfinished tooth space has been rarely investigated, because this mechanism is very complicated and the cutting behaviors are different with each tooth and even in the position on one tooth profile. In order to make clear the causes of the tooth wear and the hobbing vibration, it is necessary to know the cutting behaviors at any point on the edge. This paper describes a method of calculating the length and the thickness to be cut on each point closely divided along the tooth profile without neglecting the tip roundness. This method can be applied to any hobbing condition, e. g. to the cases of spur or helical gear, and the conventional or the climb hobbing. Some examples analyzed by this method are compared with the practical hobbing results, and then some suggestions for both wear and vibration analyses are given.

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A coupled vibration system of a pair of helical gears and gear-carrying shafts is analyzed theoretically. The coupled vibration has four-directional components, which are torsional, lateral, longitudinal vibrations and rotational one about a certain diameter of a gear. In the analyses three pairs of helical gears of different helix angles are compared with a pair of spur gears. It is shown that from the view point of the dynamic load the torsional component is the most important in the vibration of helical gears as well as in that of spur gears. It is also shown that the rotational vibration plays a more important role than the longitudinal one in the coupled vibration of helical gears. The influence of gear-carrying shafts of continuous systems is also investigate to show that the system has more than four natural modes which may be excited through helical teeth.

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Dynamic strain and accelerations of three-directional vibrations of helical gears are measured and their natural frequencies, modes and exciting force are discussed in comparison with those of spur gears. Some interesting facts are found : As in spur gears, in helical gears also the most prominent natural frequency is the one which corresponds to torsional vibration of the geared system. Some natural frequencies and modes which are not found in spur gears appear in vibrations of helical gears. As the result of resonance in these frequencies the axial vibration level and dynamic load of helical gears both increase to some extent. The exciting force due to periodic variation of tooth stiffness decreases with an increase of helix angle. Any remarkable difference is not found between levels of exciting forces of two pairs of helical gears having same helix angle but different face widths.

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