The Fourier transform technique and the theory of distributions have been applied to the analysis of dynamic and impact responses of cylindrical cavity in infinite elastic medium. The relationship between dynamic and impact responses has been discussed by means of the periodicity of loading, i. e., the parameter of Fourier transformation.

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In order to study rotating bending fatigue strengths and fatigue lives of press-fitted shafts under fluctuating load, fatigue tests were carried out under a two step pulsating load by using 29 specimens of 140 mm diameter. The test conditions are specified by the following notations : n₀ : Reversal numbers in one loading cycle. n_l : Reversal numbers under lower stress amplitude σ_l in one loading cycle. n_h : Reversal numbers under higher stress amplitude σ_h in one loading cycle. n_t : Transitional reversal numbers under the amplitude between σ_l and σ_h in one loading cycle. Six kinds of tests were made by varying the above factors, as n₀, n_h/n₀, n_t/n₀ and σ_l. The fatigue lives were converted into cumulative values of n_h by using the linear damage law. Through a logical analysis of these test results, it has been found that the fatigue lives decrease most remarkably comparing with those tested under constant stress amplitude if n₀ becomes smaller and n_t/n₀ larger, and remarkably decrease when σ_l exceeds the crack initiating limit. On the contrary, it has been also presumed that the fatigue lives increase if n₀ becomes larger, n_t is negligible and σ_l does not exceed the crack initiating limit. Irrespective of the changing of the fatigue lives, the fatigue strengths at 10 million reversals under the higher stress amplitude were scarcely affected by the test conditions.

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In this paper, it is studied theoretically that a harmonic exciting displacements generate the stationary impact vibrations in such a mechanical system with two degrees of freedom as consists of two masses with a clearance. The conditions for maintaining stable periodic vibration are analyzed and ranges of parameters are determined where asymptotic stability is assured. It is found from the results of theoretical analysis and numerical calculation, that stable fundamental impact vibration occurs in a wide range of the exciting frequencies when the clearance between two masses is close to the exciting displacement and a sub-impact vibration occurs when the frequency is high, while a two-impacts vibration occurs as the frequency becomes low.

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For the safety of nuclear power plants, piping systems of the primary loop should be designed as earthquake-resistant structures. Pipings, supported at both ends by some supporting structures, are the most fundamental configuration in a nuclear power plant. The dynamic response of a piping system to two random inputs is analyzed theoretically and the characteristics of response of such a system are discussed. And also the way of superposing its amplification factor from those of single-input models, which were already developed, is discussed. For design, an approximate formula of estimating amplification factor is given based on modal analysis method for pipings. Experimental studies are done by an analog computer. One hundred modified white noise signals are used as pseudo-earthquakes to avoid the effect of sampling or the locality of a particular earthquake. Quantitative discussions of response spectrum of this model are made.

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It is well known that the value of a drag acting on a body in an air stream may change or be controlled with the blowing air from its surface. In this study, the change of the drag acting on the cylinder with and without blowing was studied. Three types of blowing were applied i. e. blowing on total surface, upstream half surface and downstream half surface of the cylinder. At first, calculation of the drag was made from momentum change between up and downstream of the body. When the blowing was given on the down stream half surface of the cylinder, the drag decreases slightly with an increase of blowing. The reason for the increase is because of a rise in pressure and a decrease in width of the recirculation zone. The measurement of karman street in the wake of a cylinder was also made. The value of drag calculated with the measured values of the vortex street showed good agreement with that calculated by the momentum theorem.

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This paper describes a theoretical analysis of a laminar developing flow in the entrance region between parallel plates, when the inlet flow has a constant velocity gradient normal to the channel axis. The analysis is performed within the framework of the boundary layer theory, and governing equations are solved by a finite-difference method. The following results are obtained from the analysis : (1) If the flow rate through the channel is constant, the additional pressure drop in the entrance region is considerably decreased as the normal velocity gradient at the entrance section is increased. (2) As is physically expected, when isothermal walls of the channel are considered, the mean heat transfer rate is much larger at the wall of higher inlet velocity side than at the smaller inlet velocity side. However, an average value of the heat transfer rate on the two walls as a whole is smaller by a few percent than that for the case of a uniform inlet velocity profile. (3) The entrance length shows a significant reduction with the increase of the transverse velocity gradient at the inlet section.

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The authors carried out an investigation of the effects of the pump elements on the pump performance. The following conclusions are obtained ; (1) There are two types of head-capacity curves which depend on the fluid viscosity and they are classified by the vane angle and the dimension of flow channel. (2) The effect of clearance on the shut-off head is made clear with consideration of the vane angle, flow channel and fluid viscosity. (3) The shut-off head, maximum internal efficiency and torque dealt with in correlation to the dimensionless number based on vane angle, dimension of flow channel and fluid viscosity are systematically arranged. Also the shut-off head of radial vane type is ascertained with a widely changing number of vanes and sectional area of flow channel. (4) The head loss in the flow channel is determined taking into account the vane angle and the sectional area of flow channel.

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The rate of sublimation dehydration by the process of Vacuum freeze-drying was investigated after our former reports on the researches of sublimation of ice. Analyses of the temperature distribution in the sublimating materials by numerical methods and of the ideal drying-characteristics were presented. In the above analysis, the rate-determining steps considered were the rate of phase change from ice to vapor, the rate of heat supply to the sublimating surface and the rate of mass transfer of vapor through porous sublimated materials by the Darcy's and the Knudsen's flow. The analitical results were compared with experiments using homogeneous beds of sands and beef in pressure range 1-10^-2 mmHg.

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In order to study the influence of air intake and exhaust conditions on the engine performance in a poppet valve uniflow two-cycle engine, a series of fundamental equations and methods of estimating the engine performance were derived. Next a series of fundamental experiments were made on a single cylinder engine. Finally calculated values and experimental results with a four-cylinder automobile engine were compared, and good agreement was confirmed.

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Up to this time, the higher compression rations have been widely used in high speed diesel engines, but a lower compression ratio is demanded to achieve an increase in output with special regard to the stress of structure, engine noise etc. In this paper, some problems arising from the reduction of compression ratio in diesel engine were first described, and the basic data required to derive a low compression ratio in diesel engine were first described, and the periments, it was shown that the most important problems with low compression ratio are the reduction of maximum output and the increase of specific fuel consumption and this depends rather on the increase of cooling loss than on the reduction of theoretical thermal efficiency considering the rate of heat release in cycle. In the engine noise, the lower frequency part of sound pressure was reduced while, on the other hand the higher frequency part increased at a lower compression ratio. Consequently the sound pressure level of the overall range increased. In addition, the higher frequency part seems to be affected by the maximum rate of pressure rise regardless of compression ratio.

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In order to improve the multifuel capability o the diesel engine, we operated it by means of the exhaust throttling. By this technique, it was found out that the pressure of the residual gas was increased, and this made it possible to reduce that ignition delay because of a decrease in the quantity of the intake air and the rising temperature in the working gas at the end of compression. According to the experiment, utilizing a low cetane number fuel as automotive gasoline, the same combustibility as we could obtain with utilising gas oil was obtained, because the residual gas pressure was rose to about 3.0 ata. But, with a throttling of the exhaust has, fuel consumption was increased especially in a heavier load range. And yet, the smoke limited output was decreased and the engine noise became louder, because the pumping loss during the suction and exhaust stroke was increased and the charging efficiency was decreased. However, in getting such a combustibility, these are not considerably important. Because, the difficulties in running with a low cetane number fuel occure mainly at the lighter load range.

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Investigations were conducted on the undulations which occurred on the surfaces of rollers made of carbon steels (S35C, S45C, S55C) and Cr-Mo steel having hardnesses ranging from 160 to 210 H_B. Results obtained are as follows : (1) When the surface roughness of the harder roller R_max is greater than the oil film thickness h_min (based on elastohydrodynamic theory), undulations sometimes occur at Hertzian stresses lower than the shakedown limit (p_max=4.0 τ_k≒0.4 H_B which is calculated using the yield stress in a simple tension test). In this case, the amplitude of the undulations does not grow rapidly with running and running can be continued until pitting occurs because the plastic deformation is restricted to only a thin layer at the surface. (2) When h_min is greater than R_max of the harder roller, undulations never occur below a Hertzian stress of 0.4 H_B (shakedown limit). However, undulations do occur at Hertzian stresses of over (0.6∼0.7) H_B in most cases. When they did occur, running could not be continued until 2×10⁵ rotations due to growth in the amplitude of undulation and resulting large vibration and loud noise. (3) The limit stress for undulation can be increased by the following four methods ; (a) work-hardening of roller surface, (b) removal of roller surface after the first stage of running, (c) applying MoS₂ on roller surfaces at commencement of running, (d) cutting grooves on the softer roller. (4) Causes of undulation are not wear but accumulated plastic deformation at surface and / or at subsurface where reversed shear stress is maximum. (5) Undulations occur at from 10³ to 2×10⁵ rotations but never beyond 2×10⁵ rotations.

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For the process of so-called " punchless deep drawing", an optimum drawing condition is investigated under which the height of the drawn cup increases efficiently. Considering the dimensions of the rubber ring, the applied compressive load and lubricants for the contact surface between blank and die, the optimum condition for the first drawing operation is determined experimentally. It is especially emphasized that the internal diameter of the rubber ring d₂ should be chosen such that the ratio of d₂ to the die hole diameter d₁ may increase with a decreasing d₁. It is also extremely important to use a thicker ring so far as no fracture occurs at the coupled with polyethylene film. Furthermore, some examples of fractures and depressions at the bottom portion and also flange wrinkles are shown.

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