Uniaxial tension-compression tests on plate specimens of mild steel were carried out in order to obtain the characteristics of stress-strain relation to be used for analysing unloading and inverse loading processes of thin plates elasto-plastically bent by lateral load. Results of the experiment were approximated fairly well with an analytical expression on the unloading coordinate in which the effect of plastic pre-strain was taken into consideration. Moreover, influence of plastic prestrain on the relation or the Bauschinger effect was examined in detail.

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A sheath of electric cable must endure the pressure of the cooling oil flowing through it. This report gives a method for calculating the stress distribution in a spirally corrugated tube subjected to a uniform internal pressure. The method of analysis is based on a general bending theory for shells, and is applicable also to a tube with corrugation of U or Ω type. Among components of Stress appearing in the wall, the largest one in its absolute value is the direct stress at the trough in the direction of spiral. This value becomes larger as the radius becomes larger, and shows little variations with the wave height of corrugation. The shearing stress and the twisting moment are nearly proportional to the pitch of the spiral, but other stress resultants and moments hardly depend on it. The maximum stress calculated for the cable sheath of the standard type is nearly equal to the value obtained from the theory for shells of revolution.

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"A dividing differential equation method" to analyze the principal vibrations of multi-degree-of-freedom linear vibrating systems is proposed. By this method, an overall sytem is divided into several partial systems in order to make the principal vibrations of the overall system correspond one-to-one and continuously to those of the partial systems, and a first-order differential equation with an independent variable expressing the degree of connectivity among the partial systems is introduced. The theory is developed for studying the natural frequencies and the normal modes of vibration simultaneously and also for another care when only the natural frequencies are treated.A way of setting up an auxiliary system is presented. The numerical computations of the principal vibrations of an overall system can easily be executed by making use of a suitable numerical method and an electronic computer, the programming for which is very easy.

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The vibrations of a cylindrical shell of which one end is built-in and the other is combined to a circular plate or of which both ends are combined to circular plates are studies. The displacements of a circular plate and a cylindrical shell which is built-in at one end are shown in graphs. The distribution of the bending moment in this cylindrical shell is also shown.

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The present report is concerned with a statistical research on the isolation of random vibration. A model system with two degress of freedom is taken up and its behaviour is analyzed when the random excitation is loaded on the foundation. The excitation is a stationary random force with an ideally withe spectrum over all frequencies. By investigating the properties of the mean square values of absolute accelerations and relative displacements, the optimum and the worst conditions for the suspension of the above-mentioned system were obtained, and a theoretical way of deciding how to suspend machnies was explained. Moreover the authors diagramed so that many values may be decided easily.

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In this paper the forced frictional vibrations acting upon friction, which is generally expressed as a function of relative sliding velocities, are treated from the point of view of self-synchronization. First of all, the vibrations are considered as approximately a combination of two simple harmonic vibrations, one with the frequency of free vibration, the other with the frequency of excitation. The motion is considered as a bration with the frequency of excitation with slowly varying amplitude and plase, and a certain zone of synchronization is determined next. Further an experiment is conducted to verify the result of analysis.

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Experimental studies were carried out on the caracteristics of diffusers of rectangular cross section which have an angle of expansion 2θ=30°, 60°, 90°, and 180° and an area ratio of 4. Remarkabel improvement of the pressure coefficient and energy loss coefficient is achieved by means of suction at the entrance. It is found that the most effective position of suction is at the point right down stream of the corner. The diffuser efficiency increases with increase of aspect ratio. The efficiency, however, tends to be constant as the aspect ratio exceeds four. When the angle of expansion is 20°, 30°, 60°, and 90°, the rate of optimum suction is 3 to 4 per cent of the total flow rate. With this optimum suction, the efficiency of these wide angle diffusers approaches that of the diffuser of 2θ=10°.

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An experiment was carried out on the flow around a dual jet which is issued from two parallel slot nozzles set on a common end wall and is mixed turbulently with the ambient air. Distribution of cavity pressure, that of mean and fluctuating velocities, shape of the jets and cavity length were determined. From these measurements, the effect of distance between the nozzles on the flow field was studied and the following results were obtained : (1) Two jets attract each other and the axis of a jet coincides with an arc of a circle. (2) Except in the case of small distance between two nozzles, the radius of the jet axis and the cavity length increase in proportion to the nozzle distance. (3) Except in the region near the nozzle and the junction of two jets, momentum flux of the jet in flow direction is conserved.

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This paper treats the self-excited lateral vibration of a poppet valve. It is shown that the static force proportional to displacement of a valve is strongly influenced by the pressure between a valve and its seat and that the dynamic force proportional to its velocity is effected by squeezing out fluid between a valve and its seat and also by the time rate of change of momentum of fluid. The effect of squeezing out fluid has a positive damping, while the time rate of change of momentum of fluid has a negative damping. Therefore, the self-excited lateral vibration of a valve occurs, when the latter damping becomes larger than the former.

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In this report the author has made an experimental analysis on the lateral forces, the discharge coefficient, the stability and frequency of a poppet valve. The results are compared with the theoretical analysis reported already in the first report. It is made clear that (1) in order to increase the lateral stability of a poppet valve, it is necessary to make a valve seat ratio larger, to lower a valve lift and to use a working fluid of high viscocity, (2) the theoretical computations show good qualitative agreement with the experiments, and if we adopt the concept of "the effective valve seat ratio", the theoretical computations show good quantitative agreement with the experiments.

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By the adoption of M-combustion process proposed by J. S. Meurer, the low rate of pressure rise and smoother running will be assured, because combusion takes place after gradual evaporation of the fuel from the combusion chamber wall. Also, the combusion behaviour of this process is almost the same as the prograssive combusion of pre-mixed mixture, so the combusion completes quickly and better thermal efficiency will be assured. This paper covers an experiment with regard to the attempt of M-combustion applied to a swirl chamber, to improve the multifuel capability of diesel engine. And the effects on the combustibility of the wall temperature, dimensions of the fuel injection system, and engine operating conditions were discussed, and engine performances on gas oil and gasoline were compared. As the result, smoother combustion was assured by the adoption of M-combustion on swirl chamber, and if gasoline was used as fuel, exhaust smoke was reduced over a wide load renge. If this process was applied to direct injection engine such as M. A. N., there will exist a weak point concerning the formation of the combustion air swirl, but if a swirl chamber is used, this problem will be solved perfectly.

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Magnitudes of the stresses in the cutting edge during machining metals were calculated applying stress functions based on the theory of elasticity, and the accuracy of calculation was testified by the experiments on the destruction of the actual cutting edges under certain cutting conditions. In the case of machining chilled cast iron with some WC-Co cemented carbides, the results of two experiments are compered with the theoretical values. The two tests are carried out with the following purposes : 1. To find the minimum lip angle which endures the cutting force when the cutting speed is low. 2. To find the compressive strength of cutting edge for the destruction due to thermal softening when the lip angle is constant. The theoretical values are found to be in good agreement with the experimental values in spite of many hypotheses.

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