Buckling of a cylindrical shell reinforced by spiral stiffeners under external pressure was investigated theoretically and experimentally. Critical buckling pressure is determined by the energy method, and is almost identical with that for a cylindrical shell reinforced by ring stiffeners spaced with the same axial distance. The buckling pressure obtained by experiments is fairly below the theoretical one in the case of closely spaced stiffeners, and it is shown that plastic deformations due to initial imperfections cause such a decrease of the buckling pressure.

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To investigate the relation between the notch strength of a rod and that of the corresponding plate mild steel specimens, fatigue and tensile experiments are carried out. The results are summarized as follows. (1) The notch strength of a rod is greater than that of a plate for the same profile. (2) An experimental relation between fatigue notch factors of a rod and those of a plate is given. (3) Static notch strength doesn't depend on the notch root radius ρ, and local yielding is induced at earlier stage before the apparent yielding. When the yielded zone connects the opposite notchs, the stress is comparable with the lower yield point and doesn't depend on the notch shape. The notch factor of a rod estimated from that of a plate is greater than the measured one. (4) Relation between fatigue strength and static strength varies with ρ. (5) A notch constrains the deformation.

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Transient creep of pressurized circular cylindrical shells is analysed according to the strainhardening and the time-hardening theories on the basis of the power creep law and the Mises criterion. Total strain is assumed to consist of elastic and creep components. Equations of equilibrium are replaced by the corresponding difference equations in regard to the rate of displacement, and the solutions of the resulting simultaneous linear equations are integrated numerically with respect to time. Numerical calculations are performed for simply supported shells of 0.15 per cent carbon steel at 450°C subjected to constant internal pressure. The difference between these two kinds of hardening theory and the effect of the length of shells are discussed.

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The stress-strain relations for nickel-chrome steel, aluminum, and low-carbon steel were investigated under various cyclic loading conditions, such as constant strain cycling, constant load cycling with and without mean stress. The following approximate formula to represent the shape of cyclic stress-strain loop was obtained for the whole range of life excluding the initial and final periods, [numerical formula] where σ and ε denote the changes of stress and strain in each half cycle measured from the tip of each loop, σ_max is the maximum tensile stress in each half cycle and K, m, and p are material constants. Cyclic stress-strain curve proposed by Morrow can be deduced from the above formula in a special case.

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Low-cycle fatigue strength of nickel-chrome steel under various cyclic loading conditions, such as constant strain cycling, constant load cycling with and without mean stress, was discussed in relation to the cyclic plastic strain energy. Main results obtained were as follows : (1) The lowcycle fatigue strength depends on the maximum tensile stress σ_max as well as on the cyclic plastic strain energy ; (2) in the case of fatigue-type fracture, a unique relation-ship was found between the maximum tensile stress and the cumulative plastic strain energy to fracture, while in the case of unstable deformation-type fracture, another unique relationship existed between the unstable stress and the total plastic strain energy to the initiation of the cyclic unstable deformation. These relations are approximately shown by two straight lines in a log-log diagram. The line of unstable deformation-type failure lies considerably lower than the extrapolated part of the line of fatigue-type fracture.

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It was observed that the propagation rate of fatigue crack is faster under the presence of tensile mean stress. The purpose of the present study is to give a theoretical basis of the observed characteristics of fatigue crack. At first, the energies of a crack are evaluated, the elastic energy, the surface energy, the interaction energy with external stress field and the accumulated strain energy with stress cycles. Then, the energetic conditions of crack growth are discussed. It is suggested that the process of crack propagation is devided into nearly three stages, according to the size of crack, that is, the initiation, the growth of dislocation-type crack and the propagation of semi-macroscopic crack. It follows that, the mean stress have influence on every stages, which is approximately expressed in the form pV, where p and V are the hydrostatic component of stress and the volume of crack, respectively. Various other characteristics of fatigue crack are also discussed based on the energetic consideration.

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The bending and twisting fretting fatigue tests of carbon steels are carried out and the effects of cycle frequency are studied in comparison with the corrosion fatigue. The behaviors of the frictional force with progress of fretting cycles are observed. The results obtained are as follows : The fretting fatigue strength is decreased with lower frequency. The fretting damage is saturated in the early period of the total fatigue life, and the subsequent crack propagation period constitutes the most part of the life. The lower the frequency is, the shorter the saturation period. The frictional force increases initially and then decreases after showing a peak value. These changes at various frequencies well correspond to the extents of the fretting damage. Consequently, this shows that the fretting damage is attributed to cracks initiated under the frictional stresses at the initial stage simultaneously applied with the repeated stresses in the surface layers. The fretting corrosion without the repeated stresses hardly reduces the fatigue strength though the depth of wear scars is the same as that under fretting fatigue. The greater reduction of the fatigue strength by fretting under bending than under twisting may be also explained with the combined stresses.

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The behavior of the fatigue strength of annealed S 45 C carbon steel under composite stress consisting of rotating bending stress and superimposed stress of higher frequency was studied. The ratio of the frequency of superimposed stress to the frequency of rotating bending stress was selected as 11.6. It was observed that, when the ratio of superimposed stress to maximum stress was less than 0.2, the fatigue life was scarcely affected by the superimposed stress, but, when the ratio was more than 0.2, the fatigue life under composite stress was comparatively shorter than that under the stress of constant amplitude. The endurance limit was lowered by superimposing the stress of high frequency. The maximum decrease reached about 35 percent of the endurance limit under the stress of constant amplitude.

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With use of the main results already obtained from the low-cycle fatigue tests with mean stress for several materials, the authors derived theoretically the following expression : [numerical formula] where σ denotes the uniaxial stress and suffixes a, m, and e mean the stress amplitude, the mean stress, and the fatigue strength under completely reversed stress cycling for a given values of N_f ; and ζ is a material constant. This formula was checked against the experimental data obtained from some papers. The examination shows that the above formula may be used to express the effect of mean stress on the low-cycle fatigue strength approximately.

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in succession to the preceding optical microscope study, electron microscope and x-ray diffraction studies are carried out on the ultrasonic-fatigue of metals. In iron fatigued at an ultrasonic frequency, slip markings could not be observed on the whole even at high magnification (×3500), except rare occasions. This is in contrast with the feature of the specimen-surface formed by the conventional fatigue, in which ample slip bands with many microcracks appear. The mode of crack propagation in both cases, however, was not distinguishable by electron fractography. On the other hand, this observation ascertained that the surface appearance of copper-specimens fatigued by a stress cycle of the ultrasonic frequency was similar to that of the conventional fatigue. X-ray diffraction study showed that fragmentation of grains scarcely occurred in such a high frequency fatigue tests on iron.

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Using V-notched specimens of 0.36% carbon annealed steel, the effects of one impulsive load on the crack propagation and the final fracture are examined and the following results are obtained. (1) Only one impulsive load also affects the subsequent crack propagation and the final fracture and the fatigue lives are shortened. This phenomenon is more remarkable when the impulsive load is imposed during the crack propagation process and in one case fatigue life decreases to 20% of the original fatigue life. (2) There is a critical crack depth above which the effects of the impulsive load are more severe. This depth seems to correspond to the non-propagating crack depth. (3) The parallel law of crack propagation is applicable to the present results and even in the worst case results are situated in the safety range of the expected values.

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Using V-notched specimens of medium carbon steel, three kinds of fatigue tests under sinusoidally varying load are performed and following results are obtained. The rates of crack propagations are accelerated and the superposition law of crack propagation is not applicable to these test results. The reduced lives of the final fracture are about 30 or 40% of the expected ones which are estimated using the superposition law of crack propagation. Then, simple calculation method, namely multiplication law, is proposed to estimate the lives of final fracture under these varying load fatigue tests, whose method is based on the calculation using the fatigue lives under stepwise varying load and simple sinusoidally varying load fatigue tests. From these test results, authors reaffirm that some kinds of loading pattern perhaps make the fatigue lives of specimens shorter to the same degree as those of practically fatigued members, such as car axles, driving shafts and so on.

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Rigid-plastic bending of an anisotropic plate is theoretically impossible when the theory of anisotropic plasticity based on the maximum shearing stress theory is used in which the stress points are assumed to fall on any side other than the two special sides of the yield surface. It is found, however, that this problem can be analyzed in theory by considering that the stress points are at the three particular corners of the yield surface. It is proved that the results of this analysis are identical with those obtained when Young's modulus is taken as infinity in the elastic-plastic analyses of the previous report. The plate width extends or contracts and the plate thickness decreases or increases depending upon the features of the yield surface.

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In this paper, we deal with a new balancing method in which both the amplitudes of vibrations of two disks and the unbalance forces acting on bearings become approximately zero at any speeds of rotation. Furthermore, in general, it is made clear that the balancing of a flexible rotor consisting of n disks can be achieved by selecting n+2 correction planes arbitrarily.

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The authors studied the technique to estimate the step response of a complex system whose parameters are not known exactly but statistically. For the theoretical model they used a system expressed by one dimensional wave equation. At first they obtained the step response of stress and acceleration when the shape of a rod is described with a function of small variation deterministically. To prove the solution they compared it with their experimental results and got fairly good agreement between them. At the second step, they treated the sectional shape function as a stochastic variable, then they could describe the stochastic characteristics of the stress response as follows ; the mean value of the stress agrees with that of a uniform rod, and its variance becomes zero at T=1, 3, 5…, and between such moments it goes up and comes down with a quadratic shape. The maxima in each duration increase squarely.

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This paper gives the results of the experimental study of loss and secondary circulation due to various combinations of commercial elbows, and discussed the relationship between the loss and the circulation. Three general combinations are ; One where the two elbows produce a complete reversal in the direction of flow, termed the"U"bend ; and two where the two elbows produce an offset but no change in direction, termed the"S"bend ; and three where the two elbows produce both an offset and a 90 degree change in the direction of flow, termed the"twisted S"bend. The last combination gives rise to a strong single spiral motion in the straight pipe of curved pipes downstream and shows the maximum bend loss.

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In this paper are shown (1) a new treatment of the equations of motion and continuity with a little changeable control surface, and these fundamental equations are quasi-linear hyperbolic partial differential equations, (2) graphical method based on the characteristics of above-mentioned equations, (3) the analysis of the waterhammer with an air-chamber taking hydraulic losses of the outlet into consideration. As an example, waterhammer pressures are computed for two apparatuses equipped with and without an air-chamber.

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A formula for pressure drop caused by a bend is derived from analysis of energy relation in flow. The additive term in this formula, corresponding to the change of the fluid motion, is determined by the results of experiment, and is discussed in connection with patterns of flow through a bend. This formula is in good agreement with the results of experiment within the errors of measurement. The range of a pipe line in which flow is affected by a bend is similar to the case of pure fluid. Velocity of a particle through a bend and the optimum curvature of a bend with less pressure loss are also discussed in the present paper.

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Experiments on the discharged flow of both slurries of clay and Newtonian fluid through nozzles were carried out. From many experimental results, for example, on the effects of relative plug radius a, of submerged cylinder in tank, of throat contour of nozzles on discharge coefficient and the difference between the discharge coefficient at constant head and that at falling head, etc., it may be concluded that some elongation Δl of nozzle length l apparently takes place in tank for discharged flow of slurry through nozzle. On the basis of this conception, using the equivalent value ψ_a^* for ψ^*=(l/dR_εB) F (a) of nozzle, the loss of head φ={H/(v²/2g)}-1 can be determined from φ-ψ^* curve for a short tube having the same rounded-entrance as that of the nozzle. Coefficient in the discharge measurement of both slurry and Newtonian fluid by DIN and ASME long-radius nozzles can be determined using two dimensionless number R_ε and (4/an).

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An analysis on the statistical characteristics of static pressure pulsation in upward air-water flow through a smooth tube of 26.0 mm I. D. and 5.2 m long is made to have a correct understanding of the essentials of two-phase gas-liquid flow. The pulsating pressure is detected at five different locations along the tube and recorded simultaneously on an oscillograph paper. Using these data, the statistical properties such as the standard deviation, frequency function and spectral density of pulsating pressure are calculated. These are discussed with the particular emphasis on the relationship with the flow rates of both phases and the flow patterns.

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Improving the analysis of the author's previous report on a few points of importance, an exact analysis based on fundamental laws of dynamics and thermodynamics is accomplished on a simple but clearly defined model of compressible saturated two-phase flow. As the result, fundamental matters such as the behavior of energy within the two phases, the change of phase, the change of entropy, the variation of pressure near the exit of pipe in critical flow and others are clarified with physical distinctness. Besides, numerical computation is carried out for critical flow of the model afore-mentioned in case of water / steam system, and the results are presented. Distinction between critical flow with evaporation and that with condensation has an important effect on the analysis.

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This paper is concerned with the thermal stresses in a restrained-in-bending slab suddenly heated and cooled from both sides with a finite heat transfer coefficient. Such cases are very common in industries, so non-dimensional thermal stresses are calculated by computer with various Biot numbers at both sides of the slab. From these analyses the following results are obtained. (1) The thermal stresses are more influenced by the degree of heat transfer on heated side than by that on cooled side. (2) At the same temperature difference the thermal stresses become greater with better heat transfer. (3) Transient maximum thermal stress, which is a thermal shock, and the final residual thermal stress, which is a steady thermal stress, are compared with each other for various cases, and the former is shown to be important in the case where the heat transfer on heated surface becomes high.

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Transient comparison methods of simultaneous determination of thermal conductivity, thermal diffusivity and heat capacity with a plane-shaped standard sample are investigated. Series method and parallel method are proposed concerning the arrangment of the standard sample and the sample to be measured. Measuring method and necessary conditions of measurement are discussed, and the merits of the above two methods are revealed : Series comparison method is a very simple measuring method applicable to solids, powders and liquids, and the parallel comparison method is suitable for the precise measurement of relative properties among solids of resembling properties. Experimental results for plastics and spindle oil showed that the same accuracy with the transient absolute measurement could be obtained by these transient comparison methods.

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From such a standpoint that a radiation from a luminous flame is due to the small solid particles (so-called"soot"), a fundamental research for the radiation from the luminous flames of the propane-air and city gas-air was carried out on the basis of Mie theory concerning radiation. The purpose of this paper is to measure the scattered parts and attenuated parts of incident lights about a flame and study the radiation of a luminous flame systematically. A mean diameter D₃₂ of soot particles, defined as [numerical formula], where N (D) dD is the probability that the soot diameter is in the range of D and D+dD, is suggested to discuss the relation between the scattered light from the flame and the attenuated light by the luminous flame. It is showed that the values of D₃₂ obtained by scattering and attenuation are 1 400A regardless of diffusion or premixed flame. The density of the soot particles, C_v, is experimentally obtained from the attenuation of the incident light in our research, and general consideration of radiation from luminous flames is given.

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An experimental study was conducted of the effects of reduced gravity on the mechanism of nucleate boiling, using a drop tower method with high speed motion pictures and a telemeter equipment. Within the range of reduced gravity up to 0.082g, the normal nucleate boiling was observed to be insensitive to gravity, having almost the same frequency of bubble generation. The process of growth and departure of single bubbles was hardly affected by the gravity, while the process after departure was gradually influenced by it. This means that not the buoyant force but the inertia of liquid is the dominant factor controlling the departure process. Though, at lower gravities, the coalescence of bubbles became so large as to cover a part of the heater in space or time, single bubbles insensitive to the gravity were always observed at other parts of the heater in space or time, associated with little change in heat transfer characteristics.

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Viscosity of water and steam was experimentally investigated in a wide range of temperatures up to 900°C and of pressures up to 1000 bar. In this investigation, a capillary viscometer was used in the closed circuit system with a high pressure injector and a mercury manometer. Measured results are compared with the standard values of the ICPS Skeleton Table (1964), and with experimental values of other investigations. A newly correlated equation represents experimental results within about 2% deviations.

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A symmetrically scavenged two-stroke engine generally loses a part of its fresh cylinder charge through the exhaust port at the last stage of the scavenging process. As a remedy for this, the authors propose a method of throttling the exhaust by an orifice, which reflects a positive pressure wave so as to prevent an outflow of the cylinder charge. A series of experiments was performed on the effect of location, configuration and throttle ratio of the throttling orifice on the performance of an engine. It was confirmed that remarkable effects were obtained from both the improvements of engine output and fuel consumption, and the reduction of exhaust noise in comparison with the other types of exhaust system and, moreover, that an exhaust throttle of the multi-orifice type improved the engine performance over a wide range of engine speeds.

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In this paper correlations of the ignition starting gas law temperature and molecular concentration instead of a critical compression ratio were obtained under the conditions ; premixed n-heptane and air, equivalence ratio (S) : 0.5∼3, mean piston speed : 1 m/sec, without residuals, lubricant : molybdenum-disulphide. The pressure was so high that the reaction was automatically led to a hot flame after τ₁ regime. Thrice stoichiometric charge also actively burnt consuming oxygen as well as at a stoichiometry, nevertheless pressure rise rate was less than that. Cool flame starting temperatures, ignition triggers, were in a narrow range of 400∼430°C over S=0.5∼3. Shapes of indicator diagram are two-stage ignition at S=0.5, single stage ignition at S=2, 3. At S=1, two-stage ignition obviously at the molecular concentration of 0.21 kmol/m³, and at 0.43 Kmol/m³ two-stage but similar to single stage ignition.

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Der beim Anbringen eines Indikator-Druckaufnehmers am Motor entstehende Verbindungskanal verfalscht das Drucksignal. Die Verfasser haben eine Kompensationsschaltung gebaut und uberpruft, die, im Gegensatz zum bisherigen Verfahren durch Drosselung des Kanals, die im aufgenommenen Drucksignal enthaltenen Einflusse des Verbindungskanals elektronisch kompensiert. Nach diesem Verfahren erhalt man wesentlich bessere Indikator-Diagramme als bisher.

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Synthesis of the mechanisms for plane motion path generation has been done by numerical and geometric methods. These methods had so many defects that synthesis was very complicated and took more time. In this paper, these problems were solved by using the analog circuits to synthesize mechanisms clarifying the relation of each variable by tracking simultaneously with time parameter the moving coordinate of the drawing point on the connector and the fixed coordinates of the fixed pair points of the driver and the follower. Therefore, we could synthesize the most desirable mechanisms easily and in short time by changing parameters continuously in wide range.

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Externally pressurized porous journal gas bearing with solid sleeve parts, which may reduce the effects of waviness and roughness of the porous media, is introduced in this paper. The flow-model as used in the first report is also applied to this bearing so that the flow in the porous bushing may be analyzed theoretically by using the concepts of equivalent clearance and effective restricting lengths, yielding the perturbation solutions for pressure distribution. Then, the load capacity and the flow rate of the bearing are investigated by calculating the theoretical solutions, with the result that the optimum conditions of the design parameters are given for this type of the porous journal bearing.

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Assuming that the distribution curve obtained from the profile curve of the surface has a normal distribution, the relation between the surface roughness, the apparent contact area and the initial separation which is the distance between two median planes of surface in the beginning of contact is obtained theoretically. If the asperities are cones of the slopes which depend on the surface roughness, the relation between the distributions of slopes of cones and of slopes of small facets measured manually with a protractor on the profile curve is also deduced theoretically. The results of the theoretical analyses are compared with the experimental results for the initial separation and the distribution of slopes of facets on the profile curve. Results seem to support the plausibility of the proposed theory. Moreover this plausibility shows the possibility estimating the effects of the surface roughness and the apparent contact area of end faces of an object by length measurement.

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Assuming that the asperities on normally distributed surface are cones of the same slope that depends on the surface roughness, it is deduced theoretically by the slip-line theory that the real area of contact in the case of contact between a soft conical asperity and a hard flat surface or between a hard conical asperity and a soft flat surface depends on the slopes of the conical asperities, the coefficient of friction at the interface of contact asperities, and the flow pressure. If the real area of contact is corresponding to the geometrical area obtained immediately from the bearing-area curve, the relation between the real area of contact and the separation or the penetrating depth is also obtained theoretically. A comparison of calculated values based on this theory with experimental data shows good agreement.

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Assuming that the asperities on normally distributed surface are cones or pyramids the slopes of which depend on the surface roughness, the three dimensional number and the distribution of the radii of contact points are deduced theoretically. The results of the theoretical analyses are compared with the experimental results for the numbers and the distribution of the radii of contact points in the case of contact between two nominally flat metal surfaces prepared by sandpaper-finishing, sandblasting and grinding. Results seem to support the plausibility of the proposed theory. Moreover they show that over a wide load range the average radii of contact points are almost constant ; consequently the total contact area is increased mainly owing to the increase in the number of the contact points.

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This paper treats with a newly developed technique to fabricate complicated dies for press work and electrodes for electrolytic machining, which is characterized by high productivity, low cost and extreme simplicity. A number of thin wires are bound together by a retainer into a bundle so that each end of wire, which will be a surface element of an expected contour, may be pushed in with an ultrasonic vibrator to be located at a desired position. The positioning of each wire end can be controlled by utilizing a numerically controlled milling machine for instance, and the accuracy of the positioning is in the order of 5/100 mm. As the die surfaces which are constituted by a number of wire ends are not smooth, a rubber sheet is inserted between the blank and the die so that the surface of the blank may not be scratched. In electrolytic machining with a wire electrode, the surface of the product is as smooth as the one with an ordinary electrode, if the diameter of wires is less than 0.5 mm.

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In the first report, it was found through analysis that the surface condition of a compressed specimen depends on the film thickness of liquid lubricant and the roughening rate of free surface during deformation when the initial surface is flat. In this report, an experimental study on film thickness and roughening rate of free surface is presented. The film thickness on a round aluminium specimen compressed at low speed is proportional to D^2/3V^1/3p^1/3 where D is diameter of the specimen, ν is viscosity of the lubricant and p is the loading rate. The roughening rate of free surface increases with an increasing grain size of the specimen material. From an additional experiment, it is found that the true contact area with tool increases with grain size, and experimental result agrees qualitatively well with the analysis.

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