The stresses of U-type notched bars with certain inclusions of different materials under tension were investigated photoelastically. The matrix of the bar of epoxy resin and the inclusions of duralumin, epoxy resin, epoxy rubber (epoxy polysulfide copolymer) were bonded together by adhesive medium, and U-type notches were machined on both sides. The models were tested under tension with polariscope, and then the maximum stresses on the boundary of notches were investigated and several interesting results were obtained conclusively.

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A new direct stress fatigue testing machine which operates in a perfectly resonant condition under a new principle is devised and constructed. In this machine a repeated load is applied to a specimen by the inertia force of a mass forcibly vibrated by a crank and link mechanism just in a resonant condition. The amplitude of the vibration can be adjusted mechanically from zero to an arbitrary magnitude in operating condition without stopping the machine. So the starting is easy and the amplitude is kept strictly constant without any automatic control apparatus. The machine is proved to be satisfactory in operation. Some experiments are made on smooth specimens, notched specimens, and others.

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Fatigue lives of plain and notched specimens of a heat treated carbon steel are investigated under pulsating load varying in two stages. The experiments cover the cases where the stress value of the first stage is both higher and lower than that of the second stage, the stress difference between the first and second stages is varied and the stress cycle ratio in the first stage is varied. According to the result of the experiment, Miner's hypothesis seems to be effective, if scatter of fatigue lives is taken into consideration, although some exceptions are found in which cumulative cycle ratio is increased to some extent. For these exceptions, however, Miner's hypothesis gives lives on the safe side in design calculations.

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In presenting this article, it is our desire to describe the development of a fatigue testing machine for bent wire springs and shaped flat springs in sizes ranging from 0.1 mm to 1 mm diameter or thickness, and some consideration on the repeated bending fatigue strength of corrosion resistant spring materials ; nickel silver, phosphor bronze, and 18-8 stainless steel. The results indicate that when a cantilever spring is vibrated by applying force to it at the point 74.5% of the whole length from the fixed end, the effect of circular frequency of excitation in the fatigue tests is the smallest. The fatigue strength of an 18-8 stainless steel spring is notably increased as the section size of the spring is decreased, but in the case of nickel silver, the size effect on the fatigue strength is small.

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It is well-known that, in a plate under tension, a crack perpendicular to the direction of the tension causes a very high stress concentration at its tips and tends to spread, and the spreading can be stopped by drilling holes at the ends of the crack. Considering the above case and using the theory of elasticity, we have solved approximately the problem on the tension of an infinite plate containing two circular holes connected by a narrow slit. From the solution, it can be concluded that the stress concentration at the bottom of the circular hole decreases with an increase in the diameter of the circular hole and its value is very close to that given by the elliptic hole enveloping the two circular holes, but the former is larger than the latter.

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The present paper is concerned with the coupled thermoelastic problem for an infinite circular solid cylinder, whose surface is heated by heat transfer from medium at uniform temperature T₁°C. The body is supposed to be initially undisturbed. The following two cases are investigated : (1) The cylinder is free from loading, (2) The axial displacement of the cylinder is constrained and the cylindrical surface is free from external force. By means of the Laplace transformation an exact solution in the form of infinite series is obtained. Further, we examine the asymptotic behaviour of the solution for small time values. Numerical calculations are carried out for the cases of various values of the coefficient of heat transfer. Results are compared with that in the absence of thermoelastic coupling and its effect is considered.

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A method of solution to determining the thermal stress of an infinite elastic region under the conditions of linear thermoelasticity and containing some spherical cavities is illustrated by two examples for the problems containing two and three spherical cavities. The fundamental equations governing the temperature distribution of a uniform heat flow in a solid are first derived and then the elastic stresses in the solid bodies under prescribed temperature distributions are determined to satisfy the boundary conditions on the peripheries of the cavities. The method consists of a general series form of stress function in spherical coordinates, and it can be developed for a variety of cavity numbers and sizes. In this paper, the illustration for three cavities is given, and the numerical results are reported.

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In this paper, the same method of solution for the problem of determining the thermal stress as described in the previous report is illustrated by the example for the problem containing two spherical cavities. The stress distribution along the periphery of cavities was numerically calculated, so as to clarify the exact influence as exerted upon the stresses by the presence of some cavities in a heated region.

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When two periodic disturbing forces with frequencies Ω₁ and Ω₂ (Ω₂>Ω₁) are applied to a nonlinear vibratory system having unsymmetrical spring characteristics, the so-called combination tones of summed type with frequency Ω=Ω₁+Ω₂ as well as the combination tones of differential type with frequency Ω=Ω₂-Ω₁ can take place. In the present paper, the combination tones of differential type are discussed analytically and experimentally, and it is found that there are three types of the amplitude-frequency response curve of the combination tones of differential type as well as of summed type ; however, the relations between these types of the response curves and the ratios of the forcing frequencies K=Ω₂/Ω₁ are different from those of summed type. Further, introducing the conception of apparent external force, the phase angle and the backbone curves can be obtained, and the effect of unsymmetrical nonlinearity and damping force can be explained clearly.

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Experiments were carried out on 11 types of straight-edged nozzles and 11 types of roundedged nozzles which have an inner diameter of about 2 mm. These are the nozzles used for the air-micrometer, and the experiments were carried out in the case of the ratio of gap and inner diameter up to 0.1 using distilled water up to 3 m head and using low pressure air up to 500 mmAq differential pressure, and the discharge characteristics were investigated. The results are summarized as follows : 1. Excepting the friction loss and the discharged velocity energy loss, the additional loss of head which had not been clear was determined. 2. The values calculated using this result agree very well with the measured ones. So, unlike the former characteristic equations, the characteristics of double-disc nozzle with a large gap can be accurately calculated, especialy when the nozzle is sharp-edged.

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Using the same double-disc nozzles as in the third report, their discharge characteristics as high-pressure type air-micrometer were investigated under the following conditions : (1) The pressure difference up to 3 kg/cm² (2) The range of pressure ratio from 0.25 to 0.85 (3) The ratio of gap to inner diameter up to 0.1 The results are summarized as follows : 1. In using a double-disc nozzle available for the high-pressure type air-micrometer, there may occur two regions depending on the pressure ratio, the ratio of outer to inner diameter of nozzle, the inner diameter itself and the gap. In one region the viscous friction loss is prominent but in the other it is not. 2. Almost satisfactory empirical formulas which express the product of the discharge coefficient and the expansion factor, cε, were obtained for these two regions.

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Combining the experimental characteristic formulas of nozzles or orifices and double-disc nozzles which were obtained in the last four reports, characteristic equations were worked out for the low-pressure type and high-pressure type air-micrometers. The values calculated from these characteristic equations are in good agreement with the measured ones and these equations make it possible to calculate accurately the characteristics of air-micrometer in accordance with the types of nozzle or orifice and double-disc nozzle. Using these experimental formulas, some design charts can be prepared and any desired air-micrometer can be readily designed by using these charts.

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In the present paper, the spectra of total pressure fluctuation of flow for various operating conditions and measuring places are shown. They are obtained by a pick-up of condenser microphone type. These researches have brought the following conclusions : (1) The spectrum of fluctuation consists of the following two parts : i) The component, the frequency of which is (NZ)/60 c/sec or its multiples, where N is the speed of the fan per minute, Z is the number of moving blades, and ii) the component, the frequency range of which is considerably wide, and the magnitude of which is quite indefinite. (2) The first arises from the fan wheel, the second from the disturbance of the flow around the bodies in the fan. (3) The magnitude of the component which has the frequency of (NZ)/60 c/sec is proportional to the square of speed of the fan.

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The axial-flow pump was examined from the point of view of cavitation characteristics. The studies clarified the relationship between specific speed N_s and impeller diameters. According to this relationship, the suction performance of the axial-flow pump was expected to be improved by making its inlet diameter smaller than that of the outlet. Impellers of axial- and mixed-flow types, of the same design point and the same mean outlet diameter, were tested to prove the above supposition. The experiments revealed the following : in pump performance the mixed-flow impeller showed higher efficiency by 1 to 2% at normal flow and by about 5% at partial flow, and the shut-off horsepower decreased in proportion to the square of inlet diameter in the case where the mean outlet diameter was kept the same. In suction performance the mixed-flow impeller was superior in the incipience, except for K₁ cavitation, and showed about 10 to 20% higher critical S-values for drop in head and efficiency as compared with the axial-flow.

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The jet pump works by means of tendency of a stream or jet of fluid to drive or carry contiguous particles along with it. In a jet pump the maximum possible realized suction capacity Q₀ will be twice the driving capacity Q₀, because of limitations in area ratio between nozzle and throat. In the case of the newly designed 2-stage jet pump, the suction openings of the 1st and 2nd stage are connected on an even water level. Further, suction water of the 1st stage is also utilized for driving the 2nd stage. One primary objective of designing this trial pump was to achieve Q₃/Q₀=4. Changes in construction design, based on experimentation, were incorporated in the test pump unit on which test results were obtained, as follows : (1) Q₃/Q₀>4 was obtained as anticipated ; further efficiency is favorable. (2) The pump without a diffuser in the first stage outlet showed higher performance than that of a pump having a diffuser. (3) The function of the 1st stage was not influenced by opening or closing the discharge valve. The performance of the pump was, however, affected critically by operation of the suction valve of the 1st stage.

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This paper deals with a theoretical analysis of heat transfer from an inclined thin flat plate by natural convection, by using same analytical method as the author did for the heat transfer from a horizontal thin flat plate. If the laminar boundary layer exists all around the plate, the local heat transfer coefficient increases at a place near the lowest point of plate, and the difference of the coefficient between the upper and lower surface decreases as the inclined angle from the horizontal plane is increased. The average heat transfer coefficient of the lower surface is larger than that of the upper surface, and the average coefficient increases as the plate approaches to the vertical position.

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When the finned heat-transfer surface is used for heat exchangers, space radiators, or nuclear fuel elements under high temperature, there are some cases when the fin emits radiative and convective energy and are accompanied by internal heat source. There are some reports on the simple behavior of finned heat-transfer surface. But the mutual heat-transfer mechanism of fins has not yet been analysed. This report gives an analysis of the radiative and convective surface accompanied by an internal heat source. The steady state conduction equation is introduced, and solved numerically by the digital computer. Temperature distribution, efficiency and heat-transfer ratio are calculated. Various figures are introduced.

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The heat transfer and the pressure drop are experimentally studied on the extended heating surfaces with transverse fins for flow direction placed in the air channel of rectangular cross section. From the results of experiment on the effects of fin whose pitch and height are p and l respectively, channel height and Reynolds number, empirical equations for the heat transfer coefficient and the friction factor are presented. It has been shown that the ratio of fin pitch to fin height p/l is a most important factor for the heat transfer and pressure drop performance. In the case of the value of p/l=1.2∼1.6, the finned surface shows the most effective performance. The flow patterns between fins of the surface are observed and the effect of fin materials is also studied experimentally.

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Experiments were conducted to find out the influence of intermediate blades within the impeller channel on the performance characteristics of a radial turbine. In the first experiments, one or two intermediate blades were installed within each impeller channel respectively, and the influence of the number of intermediate blades upon the performance was examined. The results indicate that the installation of intermediate blades improves the performance considerably. The second experiments concern the investigation of the effect of the length of an intermediate blade upon the performance for the case of a single intermediate blade in each blade channel. The most favorable length of the intermediate blade obtained from the experiments is about 0.4 or 0.5 times the whole blade length.

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The piston temperatures of a Nissan-Automobile E-type 1200 cc gasoline engine were measured by the thermocouples, of which the lead-wires were passed through the combustion chamber and led to the stationary position. The influences of the pistion speed, load, cooling water, ignition advance, knocking and mixture ratio upon the piston temperature were examined. The following was worth noticing. (1) When the engine speed was 4 500 rpm under full load, the maximum temperature was about 200°C at the center of the piston head. (2) When the ignition timing was advanced, the piston temperature proportionally rose. Especially when knocking occurred, its maximum temperature reached 260°C, which was 60°C higher than that in case of the normal operation. (3) With weak mixture ratio, the temperature of exhaust gas rose, but there was little influence upon the piston temperature.

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Concerning the investigations on the heat flow from the piston of gasoline engine, there have been few reports. In this report, the following are described : (1) The measurement of temperature distributions of the pistons, piston rings, cylinder wall and gas in the crankcase. (2) The measurement of the rate of heat flow from every part of a piston at the speeds of 1500, 2500 and 3500 rpm and comparison of these experimental results with Ibrahim's calculation. (3) Comparison of piston temperatures, when various piston rings are used. Results are as follows : (1) Rate of heat flow from the piston rings and ring lands to the cylinder wall is 81% at a speed of 3500 rpm of full load. (2) The heat transfer coefficient on the inner surface of the piston is 35∼60 kcal/m²hr°C, (3) and besides, interesting data on the effect of piston ring upon the cooling of piston are obtained.

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In order to obtain the characteristic equation of mixed-flow propeller pumps, input headcapacity and hydraulic losses curves are investigated on the basis of experimental results by using various impellers and diffusion casings of different kinds and shapes. Both curves may be represented by flow conditions on the mean flow path, and hydraulic losses in impellers and diffusion vanes may be separated respectively into two parts, one being the friction or diffusion loss and the other shock loss. Each loss-capacity equation and loss coefficient are introduced. Using these relations, the overall characteristic equation for a mixed-flow propeller pump with an open impeller is obtained. It is seen that the agreement between measured and calculated characteristics by this equation is good except in the backflow region in the impeller. The distribution of each hydraulic loss based on this equation is also discussed.

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The profile errors due to the elastic deformations of grinding machines and workpieces in traverse grinding are analytically investigated in order to obtain the basic data for the improverment of grinding accuracy. A graphical method is employed for the estimation of the profile errors. The process of profile variation during grinding operation is also studied. The analysis shows that a constant α, which has been introduced from the elastic characteristics of machine, the grinding efficiency of wheel, the hardness of material to be ground, the property of coolant and other operating conditions, play an important role in the profile errors. The results of the analytical work have been compared with experimental data.

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Die Verfasser haben bereits die neuen Verfahren in der Ermittlung der Geschwindigkeiten und Beschleunigungen beim eine Bewegungsfreiheit besitzenden ebenen Gelenkgetriebe vorgeschlagen. Weil jedes von dem schwingenden Kurbelschleifegetriebe und umlaufenden Kurbelschleifegetriebe die Schleifbewegung auf einem umlaufenden Korper enthalt, gehen die Schleifgeschwindigkeit und -beschleunigung in die Gleichung von zweiten Beschleunigungen in diesen Getrieben und auch im Sonderfall hinein, daΒ ein Teil der Konturkurve des Plattendaumens geradlinig ist. Die Verfasser derivieren durch die Vektoranalyse die Grundformel von zweiten Beschleunigungen im Falle, daΒ die Schleife auf dem mit der Winkelbeschleunigung umlaufenden Korper schleift, und wenden die Formel auf die vorerwahnten Getriebe an. Die zweiten Beschleunigungen in diesen Getrieben sind einfach und genau durch das graphische Verfahren zu ermitteln.

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The authors analyzed an externally pressurized porous thrust gas-bearing in the previous paper. In such type of bearings, their characteristics are much affected by the roughness of porous surface of bearings. In this paper, to avoid such effect and to improve the bearing performance, the authors investigated the porous thrust gas-bearing with flat and solid ring surface, so-called 'flange', around the porous part. They applied the previous theory to this case and obtained the theoretical pressure distribution and load capacity. The experimental results coincided well with the theoretical ones qualitatively and fairly well quantitatively.

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The experimental and the theoretical researchs were performed on the cold-roll forming of metal strips to the cross section of circular arc through a set of the upper roll and the lower. From the experiment, it was found that the membraneous strain in the strip was negligibly small as compared with the bending strain. Therefore, the cold-roll forming was treated as a biaxial bending problem. The roll force and torque were analyzed by means of the strain energy method. The theoretical results were in good agreement with the experimental results.

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In the case of forming a sheet into cylindrical surface by stretching the sheet in circumferential direction under various conditions, the effects of time and magnitude of stretching are studied experimentally and theoretically. The experimental results are well explained by the results of theoretical calculations. The obtained results reveal that the springback decreases with an increase of the tensile force, and the amount of it is minimized when the sheet is only stretched after bending. It is also found that the difference in the springback between stretching after bending and stretching with bending is small for materials having a remarkable Bauschinger effect and large for materials having little such effect. Furthermore, it is found that if it is necessary to stretch the sheet during bending, in order to decrease the springback it is desirable that the tensile force be maintained as small as possible during bending and finally a large tensile force is worked after release of the first force.

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The bending deformation of material under the punch at the shearing time causes a deflection of sheared blanks. Moreover, because of the spring back of the bending, the diameter of sheared blanks is not always equal to the diameter of the die hole. The authors, in this paper, analyzed the bending moment and the axial force, which cause the deflection of the material, and made clear the effect of spring back on the dimensional accuracy. These analytical results were also confirmed by experimental results.

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This paper gives an account of the effects of drawing conditions on the drawability, using soft, half-hard and hard aluminium sheets of 0.4 mm in nomimal thickness. The drawing conditions examined included punch profile and lubricants over punch head. In order to clarify the mechanism of the fracture to govern the drawability, the fracture forces (i.e. the supportable drawing tension of metal sheet over punch head) were compared with the drawing forces throughout the drawing process and the strain and stress distributions of metal sheets over punch head were examined experimentally. As the result, three basic rules to control the fracture of metal sheets during the drawing process have been established. According to these basic rules, the effects of the drawing conditions on the limiting drawing ratio could be systematically understood.

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