In order to study the variation of the strength of mild steel with increased strain rate, we deal with the dynamic plastic bending of a cantilever. The cantilever can be assumed to be made of a rigid-plastic material when plastic deformation is large compared with elastic one. In the model of rapid bending of the beam proposed by Lee and Symonds, entire deformation is assumed to take place at a moving hinge at each instant, and there the shear force to be zero, since the hinge is the point of maximum bending moment. But in the case where the cantilever is struck transversely by a rifle bullet, the assumption that the shear force is zero is not reasonable because the effect of rotary inertia is not negligible. Thus an improved theory considering a certain shear force at the hinge is proposed and some results of experiments and analyses as a basis of our theory are presented.

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The purpose of this paper is to develop a practical method of stress and deformation analysis of body structures such as sedans and station wagons subjected to bending or twisting loads. Many of these are reinforced shell structures, the so-called"semi-monocoque"type of construction, but they contain relatively enormous structural"cut-outs"(such as door and window openings). In conducting research, an attempt is made to analyze the car body as a structure consisting of rigid frame parts and reinforced shells both components being rigidly jointed. The matrix method of structural analysis is used and the calculations are carried out on the digital computer IBM 7074. In order to check the validity of the present method, experiments are carried out on two-and three-dimensional models. Comparison between the calculated results and the tests indicates that the agreement of stress and deflection is fairly good.

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The compressive yield point and the flow stress to cause a certain amount of compressive strain of 0.03%C steel were obtained experimentally within the range of strain rates of 2∼200/sec. The ratio of dynamic yield point to static yield point is 1.6∼2.5 and the ratio of dynamic flow stress to static flow stress is 1.0∼1.6. The yield point and flow stresses begin to be affected evidently by the strain rate in the region of the strain rate of more than 1/sec. And the stresses increase rapidly in the region beyond the strain rate of 100∼200/sec. By the repetition of impacts, the strain increment caused by one blow decreases with the repeating of impact. But at low stresses, the early blows cause very small strain and the strain is produced appreciably thereafter.

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A 0.22% carbon steel and a"roll material"have been fatigue-stressed in the high stress levels under rotating bending with very low frequency in order to investigate the stress-strain behaviour in the plastic fatigue process. The constant strain tests as well as the constant stress tests have been conducted to compare both results. As a result, the curves of variation of strain or stress with number of stress repetitions have been obtained and the tendency of variation of the stress-strain hysteresis loop as well as the dynamic modulus is also reported. The special interrupted fatigue tests under constant stress amplitude have been performed to obtain some information about the effect of unloading, aging and reloading on the fatigue lives and the stress-strain behaviours. The multiple repeated stress tests of two-step level have been carried out, too, and the relation between the Palmgren's criterion Σ(n/N)=1 and the stress-strain behaviour under such conditions are discussed.

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Following the previous studies under cyclic bending stresses, the changes in half-value breadth, residual stress, hardness and microstructure have been investigated under completely reversed torsional stress amplitude and under alternating torsional stress with mean stress. It is found that the mean stress has little effect on the aforesaid changes. So it is deduced that, in the case of torsional stresses, the fatigue mechanism is not influenced essentially with mean stress, and consequently mean stress has little effect on fatigue life. It is also found that in torsional fatigue, tensile residual stress appears on the specimen surface at the initial stage of fatigue, and then it decreases with the number of stress cycles. It seems that the tensile residual stress is due to the absorption of excess vacancies, which are produced with stress cycles, by specimen surface.

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In order to perform the precise micro-hardness testing, it is very important to understand the basic effect of method of preparing specimens. So investigations on the conventional methods of preparation have been conducted. Using three kinds of metals, experiments on the mounting of specimen, the grinding, the polishing and the micro-hardness testing have been done. The results are as follows. (1) Polyester resin is better than others to mount specimens. But the initial stress becomes about -450 kg/cm² for mild steel and -150 kg/cm² for aluminum. Accordingly low strength materials such as single crystal metal and aluminum had better not be mounted. (2) Residual compressive stresses occur near the surface ground by the emery papers. On the other hand, residual tensile stresses occur near the surface polished by the lapping wheel with a well piled polishing cloth. (3) It is very reasonable to practise polishing after grinding, because the residual compressive stresses near the surface reduce remarkably.

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When the unsymmetrical rotor with angular velocity ω is excited by a periodic external force having frequency ω₀, two forced vibrations of frequencies ω₀ and ω₀'=2ω-ω₀ take place simultaneously. Depending on the circumstances, the amplitudes of the vibration of frequency ω₀'become remarkably larger than the amplitudes of the harmonic oscillation, i.e., the forced vibration of frequency ω₀. Thus the idea generally accepted for the forced vibrations, that"the frequency of the forced vibration is equal or relates to that of the external force"is not always applicable for the forced vibrations of the shaft carrying an unsymmetrical rotor. In the present paper the response curves, the amplitude ratio between two forced vibrations, the effects of the damping forces are discussed analytically, and the obtained results are ascertained through the experiments.

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Some of the tables of machine tools vibrate in the cutting process, no matter how uniformly they move when the machine is not working. In this paper, the vibration of a hydraulically driven table is analysed theoretically on the basis of the pressure-flow characteristic of flow control valve, the equation of continuity for oil flow, the equation of motion for sliding element, the friction-velocity relation between sliding surfaces, and the relation between the table motion and the cutting force. An experimental verification of theoretical analysis is made using the vertical milling machine of which the table is driven by hydraulic power.

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To eliminate the influence of the load inertia variations in servomechanisms, the energy feedback method is introduced. In this method, the manipulating energy is taken as a local feedback signal for the compensation of the load inertia variations. The energy feedback control system is analyzed by the phase plane technique, simulated and computed on an analogue computer. The energy feedback control is based on the optimum nonlinear control, and is furnished with the adaptive characteristic to load inertia variations besides the latter. In the conventional optimum nonlinear control system, the switching line of the manipulated variable is fixed on the phase plane. In the energy feedback control system, however, the switching line is not fixed but calculated during the transient response from both the error and the operating energy which follows the load inertia variations of the system. Consequently, the system applying the energy feedback method shows a remarkably adaptive characteristic to the load inertia variations.

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This study is generally concerned with the laminar, meridional flow in an arbitrarily shaped narrow gap between two axi-symmetrically formed walls. In this paper, a momentumintegral method is used to obtain the solutions for the downstream region where the exact series solutions obtained in the first report are no longer valid. Together with the usual Pohlhausen's parameter ∧=δ²/νdU/(dx), a new shape factor Γ=h²/U(∂²u/(∂y²))_y=k is introduced, which results in smooth changes of the hydrodynamical quantities from the inlet region to the filled region, and a rigorous theoretical expression of the pressure distribution containing both the inertia and the viscous effects of the fluid flow. As an example, detailed numerical calculations have been made for the radial outward flow between two parallel discs. The important conclusions are : the breadth of the separation region changes largely with the Reynolds number, and separation does not occur when the Reynolds number is less than a critical value R_cr≅100 : in the downstream region where X={1+x/(r₀)}²2R≅0.5, the influence of the flow condition close to the entrance disappears practically.

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In this paper, the flow configuration of the two-phase slug flow, which contains small bubbles in the liquid slug has been analysed. The experiment has been carried out for air-water two-phase upward flow in 27.6 mm ID glass tube, using the electrode probe which indicates the void ratio fluctuation. The new parameters such as the ratios of the large bubble (Taylor bubble) volume (f_dB) and of small bubbles volume in liquid slug (f_dS) to a control volume, the void ratio in gas slug section (fd₁) and the void ratio in liquid slug section (fd₂) have been introduced. These parameters except fd₁ are given experimentally as the funtion of mean void ratio fd only. They are as follows : fdB=fd^1.8 fdS=fd(1-fd^0.3) fd₁=<0.65> fd₂=fd^1.8

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This paper has presented the formulas to calculate the absolute velocities of the gas slug (Taylor bubble) w_B, the small bubbles in the liquid slug section w_S, the liquid in the liquid slug w_w and the liquid film around gas slug w_F by the mean void ratio and gas time ratio. The experimental values of the absolute velocities are expressed by the following empirical formulas for air-water two-phase upward flow in 27.6 mm I.D. tube. w_B=1.25(w_wo+w_do) ; w_S=1.10 (w_wo+w_do) ; w_W=0.96(w_wo++w_d0) Also the absolute velocity of the gas slug has been directly measured. The distribution characteristics of the small bubbles in the liquid slugs have been presented. It has been estimated on the results that the axial pitch is longer than the radial pitch, namely the small bubbles do not distribute isotropically.

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The authors tried to explain the effects of the dimensions of a vortex tube (especially the rate of partial admission of nozzle) on the energy separation of gas flowing through it. They tried also to explain the influence of the cold air rate on the flow and thermal fields in a vortex tube with the optimum proportion of the total area of nozzle openings (F_n) to the cross-sectional area of main tube (F_t). From these researches the following results have been obtained : (1) The maximum efficiency of energy separation is obtained when F_n≒0.17F_t. (2) The values of turbulent diffusivity calculated from the tangential velocity profiles nearly coincide with the values computed from Keyes'empirical formula. Reynolds number of jet from the nozzle, R_et=(0.5∼3.0)×10⁶. (3) For the case of large axial velocity, the modified formulae including the axial velocity terms (36) and (37) should be used to predict the stagnation temperature profile in the cross-section at the cold end of the tube.

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In order to reduce the loss of flow in the conical diffusers of large diverging angles, boundary layer suction through a single slit at the entrance is examined. Experiments are carried out for conical diffusers having area ratio of 4 and diverging angles of 10∼60 degrees. The loss coefficient decreases to the value of 0.2 for all angles of divergence, when the rate of suction quantity is 2%. Theory for the optimum rate of suction is discussed. A method to find out the separation point by powder is also examined.

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The radiation heat transfer mechanism is one of the significant problems in engineering. This problem is centered on the determination of the overall radiation interchange configuration factor. In the past, Hottel, Yagi-Kunii, Sparrow and Gebhart introduced the methods of calculating the overall configuration factor in the enclosure. But these methods have been too complicated for practical application, and are not suitable for making an accurate analysis and calculation. In this paper, a new method for determining the overall configuration factor within an enclosure filled with absorbing medium is described. Even if the enclosure is composed of a complicated shape and a number of surfaces, the conversion method expressed as a matrix form leads to a systematic and efficient solution of the overall configuration factor.

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In using convective and radiative fins on heat exchangers, space radiators or nuclear fuel elements at high temperature, there are cases when the thick fins emit radiation and convection energy to the enclosing gas. In this paper, an analysis of a thick plate and annular fin is made. The two-dimensional temperature distribution and efficiency of the thick fins are solved by the digital computer. The numerical solution of the net-convective and net-radiative plate fin is presented. Lastly, the relation between the efficiency of the thick fin and that of the thin fin is discussed.

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In using radiative and convective fins on heat exchangers, space radiators or nuclear fuel elements for heat release at high temperature, there are cases when the surface of the fins emits radiative and convective energy with mutual irradiation. Most of analyses studied thus far have been carried out for an isolated fin and have neglected the mutual irradiation. In this paper, thermal performances of radiative and convective plate-fins are systematically analysed on the basis of a derived steady-state integro-differential equation. This has been solved for a wide range of values of the normalized parameters. Lastly, the relation between the cases when there is mutual irradiation and when there is not is formulated.

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In order to solve problems arising in heat removal from gas cooled reactors, several thermal tests by an out-pile mock-up loop capable of giving same condition as in-pile operating condition are considered. This report presents the information concerning the various specifications, structures, installations, hazard preventing systems, functional tests and modifications of an HTPG (high temperature pressurized gas) loop. Many modifications of a sealing mechanism of the main circulator are made, especially for high temperature operations. Final design and tests of the blower-shaft seal and its purification system are described. Furthermore, heat removal tests of the polygonal spiral fins are made by the use of the HTPG loop. Lastly, the result of the test suggests that the polyzonal fin is a useful surface for extremely high-flux heat transfer.

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An MHD generator, with constant flow sectional area of 50×120 mm and active length of 1 000 mm, was constructed and experiments were conducted using combustion gas as working fluid. Generator channel was composed of MgO insulating walls and 20 segmented graphite electrode pairs and magnetic field of 14 kG was applied. Voltage, current, and output power characteristics were investigated under various conditions and maximum output of 17 kW was obtained at 7 MW input. The analysis of the generator was done assuming one-dimensional flow and the results were compared with experiment. As to induced voltage, theoretical and experimental results showed good agreement, but there was substantial discrepancy as to current and output power. By esimating, however, the electrical conductivity of gas lower than the theoretical value, agreement was improved. From this it may be concluded that, apart from the problem of electric conductivity of gas, the one-dimensional hydraulic flow analysis of channel represents the reality fairly well even on this scale of generator.

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The thermocouple wires were led from the connecting rod to the piston through in a coil which received a twisting stress only in the piston pin. From here the wires were led out by means of the"combustion chamber pass through and on the circular spring"method that had been used by the authors. From the measuring results, the followings were found. (i) The heat flow from the piston reaches to the middle part of the connecting rod, at the big end, however, this effect fade away. The temperatures of the crankpin and main bearing metal rise a certain extent above the surroundings by the friction. (ii) These temperatures are increased proportionately with the engine speed. (iii) An increasing the oil temperature increases the temperatures of the bearing-metals as same extent as it.

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The Cr-plated top piston-rings were irradiated, then the each amount of the radioactive wear debris of chrome and cast iron part were separately measured by mean of R.I. method. The main results of this investigation are as follows : (i) Wear of cast iron of the side faces is a several times or more as large than chrome of the sliding face. (ii) Wear of the cast iron is influenced sensitively by the oil-film-thickness. (iii) Additives of lubricating oil prevent mainly the carrosive wear, and its effectiveness is small when the normal runnig. (iv) When the piston-ring receive a high load, moreover the knock is occur, the wear is increased very sharply, specially the chrome part. (v) Dust is the most harmful, and air cleaner plays a very important part.

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The circular-arc-toothed cylindrical (CATC) gears can be generated by a circular-arc-toothed rack, such as the spiral-bevel gear-cutters of Gleason-type. In this paper, the characteristics of CATC gears with zero-spiral angle at the center of the face-width were studied ; the gears were made on the machines originally designed by the author to get high-precision cut or ground gears, and the following results were obtained. (1) At the center of the face-width, the tooth profile is shaped to an involute curve, but toward the both ends of the tooth, it deviates from the involute. (2) Not withstanding the above fact, the conjugate action of the teeth is obtained. (3) The gears with a desired crowning can be cut and ground without difficulty. (4) Even if the parallelism of the gear shafts is injured by the manufacturing errors or elastic deformations, the tooth-end-bearing can be avoided like in the case of the spherical rolling bearings.

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This paper treats experimental results on the mechanism of metal cutting with oscillating tools. In order to measure the cutting forces precisely, it is desirable that a tool be vibrated with a low frequency because there are many troubles in the experimental procedure of cutting if the tool is oscillated with a high frequency. Aluminum and brass are machined two-dimensionally with tools vibrated with 33 c/sec frequency and 0.2 mm amplitude. The depth of cut is varied from 0.03 to 0.15 mm and the rake angle from 0 to 40 deg, at the surface speed of works of 0.37 m/min. The cutting forces increase gradually with the increase of cutting distance in one cycle. This is more evident for the thrust force than for the principal force. Further investigations are now performed on the coefficient of friction on the tool-chip interface, the stress in the shear plane, and the effect of elliptical movement of a tool on the thrust force.

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The generating mechanism of the elastically produced errors had been clarified in the first report. There remain, however, some questions about optimum grinding conditions, under which the appointed accuracy can be obtained most efficiently. In this report, from such a viewpoint, the authors introduced the profile improving coefficient and the residual stock removal coefficient which showed the variation of profile errors in traverse grinding. The effects of grinding conditions on the profile errors were analytically investigated with these coefficients, and the results of the analysis were compared with the experimental results. Operating methods to prevent the profile errors on the end of a workpiece were also studied. And, it was shown that the limitation of the over-run of wheel and the adequate time of the dwell were considerably useful for improving the accuracy of workpieces and the grinding efficiency.

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Theoretical and experimental researches were performed on the shaving mechanism of sheet metals. From the experiment it was found that the shaving deformation processes of aluminum plates could be divided into three stages, indentation, chip formation and shear fracture. In the theoretical research, three slip line fields associated to the above stages were assumed, and the shaving load-punch penetration curves were calculated. Moreover, the influences of the shaving conditions (shaving depth, rake angle of die and metal temper) on the configuration of the shaved surface became clear.

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