In the previous paper, the authors studied on the crack depth of a smooth specimen subjected to corrosion fatigue under a cycle frequency of 2300 c/min in saline, and the low temperature embrittlement of specimens having such corrosion fatigue cracks. In the present paper, the corrosion fatigue is given under a cycle frequency of 2300 c/min in tap water and 760 c/min in saline by repeated bending and also under 2300 c/min in saline by repeated twisting to make clear the influence of the crack depth on the embrittlement transition temperature of the materials subjected to corrosion fatigue under more extensive test conditions. The crack depth due to corrosion fatigue depends upon the damage of corrosion fatigue (k-1)/(k_c-1), irrespective of the conditions of corrosion fatigue such as the intensity of corrosive, the nominal stress, the cycle frequency, and either under repeated bending or repeated twisting, where k represents the corrosion effect proposed by the authors and k_c corresponds to k at the rupture time. The crack propagation rate under bending of the nominal stress σ_c is given as a function of the true stress σ_ck acting on the root of the corrosion fatigue crack. The embrittlement transition temperature T_r of the specimens having these cracks rises with the square root of the crack depth and is in an exponential relation to (k-1)/(k_c-1) under wide working conditions of corrosion fatigue.

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The authors have carried out rotary bending fatigue tests on large cylindrical specimens (0.2% carbon steel) having a circumferential groove welded by manual electric welding and also on small specimens taken from the welded part of the large ones. Two series of specimens, stress-relieved and not stress-relieved, have been tested in order to investigate the influence of residual stress at the same time. The results are summarized as follows : (1) The fatigue strengths of the large and small stress-relieved welded specimens have decreased to 43% and 58% of that of the solid specimens having respective sizes. Such decrease of fatigue strength may be caused by the defects such as blow holes in welded metal, which may result in the sharp notch effect. (2) The fatigue strengths of the large specimens which were not stress-relieved have decreased more remarkably, and are 38% of that of the solid specimens. However, for small specimens, the fatigue strength has not practically shown any effect of stress-relieving.

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Utilizing the physical meaning of interference of notch effects in two-dimensional elasticity, the author developed a method of calculating the stress in a plate due to the effect of interference of many notches. By this method, the stress concentration factors of an infinite plate containing an infinite row of elliptic holes subjected to tensile load were calculated. When the ellipses degenerate to circular holes, the stress concentration factors obtained by author's method are in close agreement with the exact values obtained by Howland and Isida.

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A method for solving the fundamental differential equations for the symmetrical problems of toroidal shells is proposed in this paper. The perturbation method is used, and the solutions are obtained in such a form that the numerical values of the solutions may be easily found, if the values of the parameters are given. The ranges of the values of the parameters in which the solutions are available with satisfactory accuracy are checked.

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In order to verify the usefulness of the method for solving the fundamental differential equations for torcidal shells, which was proposed in the first report, some examples of application are shown in this report. The first example is concerned with the bellows, the second with the Ω joint, the third again with the Ω joint of another type, and the fourth with the problem of thermal stresses of pressure vesscls.

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The Lagrangian in the vibration of a circular arc bar in its plane is discussed and the radial and tangential displacements are obtained in general forms. The frequency equations of a circular ring and a circular arc bar with hinged ends for the vibration in its plane are obtained and they are compared with the already known solutions. Then, the frequency equations of a circular arc bar with both ends built-in are obtained from the Lagrangian and the nondimensional frequencies are shown in figures. Also, for the vibration of a circular arc bar with free ends, the nondimensional frequencies are calculated and are shown in figures.

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The vibration of a circular arc bar which occurs perpendicularly to its plane is studied. Its Lagrangian is obtained and from the condition to minimize it, frequency equations and boundary values can be obtained. For a circular ring and a circular arc bar with both ends built-in, the frequency equations obtained by the method mentioned above are compared with the known ones. For a circular arc bar with both ends free, the frequency equations and the boundary values are obtained and some frequencies are calculated and given in graphs. Also, it is ascertained that the centre of gravity of the circular arc bar does not move during the vibration.

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When two periodic disturbing forces with frequencies Ω₁ and Ω₂ excite a nonlinear vibratory system, combination tones having a frequency Ω=Ω₁+Ω₂ appear. In the present paper, the combination tones are discussed analytically and experimentally. For a small value of frequency ratio K=Ω₂/Ω₁ (Ω₂≨Ω₁, K≨1), the response curves of combination tones are hard or soft spring type, and the magnitudes of amplitude increase with the value K and the value of the unsymmetrical nonlinearity. When the value K is somewhat large, peculiar response curves take place, and the amplitudes of harmonic oscillations become larger than those of combination tones. By introducing the conception of apparent external force, the back bone curves and the phase angles can be obtained, and further, the effects of unsymmetrical nonlinearity can be explained clearly. Generally, the amplitudes of combination tones are comparable to those of ultraharmonic oscillation.

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It is generally impossible to obtain the exact response of nonlinear control systems by the integral method. It is necessary, therefore, to use the approximate methods such as perturbation, iteration or others, when we intend to study the systems by the analytical method. The solution will be represented by infinite series, and the first several terms will afford an approximate solution. Then, the convergency of the solution and the accuracy of the approximate solution must be estimated, being compared with the numerical solution, which has a significant meaning in the theoretical study of nonlinear control systems. The author devised a modified Runge-Kutta method. He proved that the mcdified method is less troublesome in calculation with better accuracy than the conventional method in the illustrative analysis of the indicial response of gain-saturated second order servomechanism. He believes that the modified method will be superior to the conventional one in the general nonlinear gain systems or, moreover, in the general nonlinear control systems.

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Several types of system controlled by two or three human operators were investiaated to know fundamental characteristics of a manual control system including many human operators. Controlled systems were simulated on an analog computer. Cathode-ray-tubes were used as displays, and small light handles of disk type were used in order to eliminate dynamics of handle systems. The results showed that : In the system composed of serially connected operators, its characteristics are nearly equal to the enlarged characteristics of a unit-element. In the closed-loop system with operators connected in series, adaptive characteristics of human operators produce an undesirable influence, which can be eliminated by a minor feedback path. In the system composed of operators connected in parallel, operators' outputs tend to drift due to interaction between them. In the two-dimensional control system with strong interaction, the control by a single operator brings better results than the control by two operators.

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The conveying state of concentrated particles changes sensitively according to the local concentration of the particles, namely, with an increase of the local concentration of particles the acceleration factor of particle "k" decreases rapidly. Firstly, the new constant denoting the concentration of particles "m" modified from the mixture ratio "μ" by taking account of the specific weights and the velocities of air stream and particle, and the distribution of particles in vertical direction, is defined. Secondly, from the experimental results on the dispersed state of particles, the decreases of the acceleration factor k/k₀ are measured, where k₀ stands for the acceleration factor for a single particle. From the above investigations, the following empirical formula is obtained. [numerical formula] By using the above formula, we can presume the velocity of concentrated particles and the clogging of a pipe.

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In the flow of molten high polymers through capillaries, an instability occurs at shear stresses 10⁵∼10⁸ dynes/cm². The instability results in emerging streams of irregular shape. Several explanations of extrudate irregularities have been published up to the present, but they may be considered to be insufficient. In this paper, considering that the flow states of a viscoelastic fluid are governed by the elastic force, the viscous force and the inertia force, two dimensionless numbers R_e^* and N_E are deduced. Then, it is verified by the experiment that the onset of instabilities in an extrudate of molten high polymers depends on these dimensionless numbers R_e^* and N_E.

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Authors manufactured for trial a new type of electromagnetic induction pump in which electromagnetic force contributes to the revolving motion of the fluid, and induces pressure by means of centrifugal force. It was constructed with a casing made of SUS 27, shaped like an ordinary centrifugal pump, and with two disk stators on both sides fed with a three phase alternating current. The pump was designed to deliver 60 l/min of molten tin at 250°C against a pressure of 3 kg/cm². Testing apparatus consists of a pump, a 2 in. pipe line, a tank, two throttling valves, an electromagnetic flow meter, two pressure gages and some heaters. An approximate solution of the pumping action was obtained, and the analytical results agreed roughly with the experimental ones.

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Regarding the axisymmetric flow through an axial-flow turbo-machine, the radial equilibrium theory and the actuator disc theory have been expounded, in which the effects of impeller breadth and blade shape have not been considered. In this paper a method is presented, in which the above mentioned disadvantages are eliminated. To the axisymmetric flow through a turbo-machine of the free vortex type, the author applies the fundamental partial-differential equations derived from the equations given by Lorenz and Bauersfeld, and the following cases are treated. (1) The flow through an impeller at the off-design point is treated on the assumption that the flow in front of the impeller is a potential one, and numerical examples are shown. (2) The flow through an impeller at the design point is treated on the assumption that the flow in front of the impeller is an inviscid shear flow, and it is shown that the flow in the rear of the impeller has a more uniform axial-velocity distribution.

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For the purpose of investigating the aerodynamic damping effects on vibrating cascade blades, the authors made a water tunnel with a linear cascade in which five blades vibrate in a translatory mode with arbitrary frequency and phase angle between the adjacent blades. A series of experiments were carried out on an isolated blade and on the cascades with the following conditions : Blades : NACA 65-(12) 10 (fixed : 8, vibrating : 5) chord : 30 mm span : 60 mm solidity : 1 stagger angle : 0°, 30° amplitude of vibration : 2 mm The experimental results were analyzed by comparing with the theoretical ones hitherto obtained and with the aid of the considerations about the quasi-steady force of vibrating blades.

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Among theoretical studies about the aerodynamic force acting on vibrating blades in turbomachines, Whitehead's theory is the only one that has ever been undertaken for treating both stalled and unstalled blade vibrations on a unified basis. Unfortunately he made mistakes in comparing the order of magnitude of infinitesimal quantities, and moreover the assumption of the actuator disc cannot be expected to give a stability criterion for the blade flutter, because the assumption itself means that the reduced frequency is always zero, so his theory could give nothing but the erroneous results. Nevertheless, the actuator disc method first applied by him to the vibration problems is very promising. This paper, correcting his mistakes, gives a theoretical method of calculating the aerodynamic force by the "semi-actuator disc" method which is an extension of the actuator disc method.

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In the 1st report fundamental equations for calculating the aerodynamic force acting on the cascading blades vibrating in a translatory mode were given. This report shows the results of the calculation and gives the criterion for the flutter (the boundary of the region where the aerodynamic damping force cannot be negative).

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The analysis of the flow in an impeller passage of a mixed and inward-flow radial turbine is very difficult due to many effective factors such as inertia force, Coriolis' force, three dimensionality, viscosity and compressibility. In this report, an approximate analytical method is presented for a steady three dimensional flow of nonviscous and compressible fluid through the impeller of a mixed and inward-flow radial turbine. To measure the pressure distribution on the rotating blades of the impeller of a radial turbine, a mixed and inward-flow radial turbine was manufactured. The experimental results are compared with those by theoretical analysis and good agreement is found to exist between them. It is also shown that the torque calculated from theoretical pressure distribution is in fairly good agreement with the torque measured by experiment.

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Combustion noise of the Diesel engine of a pre-combustion chamber type will be originated by some mechanical cause involved with sharp pressure rise in the main chamber. This pressure rise is determined by the rate of heat release in it and the quantity of gas issued from the auxiliary chamber. In order to clarify the latter effect, which will be closely related with the pressure rise in the auxiliary chamber and the area of the connecting passage, an air model was proposed. The pressure rise in the main chamber caused by a sudden pressure jump in the auxiliary chamber was measured in various areas of the connecting passage, and was compared with the theoretical calculation in which gas inertia was neglected. As the result, it was found that the rate of pressure rise in the main chamber is proportional to the area ratio of the passage and inversely proportional to the volume ratio of the main chamber. Application of the result to the actual engines shows that transmission of rapid pressure rise in the pre-chamber to the main chamber is strongly suppressed, resulting in a smooth pressure rise with the pre-combustion chamber type engine, while it cannot be with the swirl chamber type.

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It was suggested in the previous paper that the area of the connecting passage in a divided chamber type Diesel engine determines whether a sharp pressure rise in the auxiliary chamber transmits to the main chamber or not. No attention, however, was paid to the pressure wave propagation in the combustion chamber that would possibly be of importance. In order to make up for this, the water analogue method was applied simulating such a two-dimensional unsteady flow problem. Test results show that, with a wide connecting passage, a sharp pressure pulse is formed and spreads in the main chamber, followed by a rapid pressure rise and pressure vibration of relatively low pitch. Such pulse and vibration decline with a decreasing of the area of the passage and with a smoothing of the pressure rise in the auxiliary chamber. Owing to this pulse, the maximum rate of pressure rise in the main chamber is exceedingly larger than the theoretical value predicted in the previous paper, while the average rate virtually coincides with the latter if fine waves are ignored.

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When starting the design of a muffler, the attenuation characteristics to be muffled must be prepared in advance. It is intended, in this report, to study a method to find the attenuation characteristics through calculation. In this paper, firstly the author has studied about the desirable standard level for designing an exhaust muffler, and secondly about the method of converting the sound pressure of the desirable noise level and the exhaust noise to power level, and then a whole system for designing a muffler was shown in various steps. Finally, an example of calculation for a real engine was presented.

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This report deals in applications of ceramics in machining several kinds of work material and it is divided into three major parts : (1) Types of failure and wear process. In this chapter it will be discussed what kinds of failure will take place on the flank and the face of cutting tools and how it will increase. (2) Applicability of the tool life equation. With brittle tool materials such as carbide and ceramic tools, the relationship between the tool life T and the cutting speed V can not be expressed by a single line on the so-called V-T diagram. It has been clarified in this chapter that such a phenomenon is caused by the presence of the welded fragments on the cutting edge at low cutting speeds and heat shock at high cutting speeds. Thereupon the numerical values with the cutting conditions have been obtained theoretically and experimentally. (3) Applicability of ceramic tools in machining. Firstly reliability of several kinds of ceramic tools has been revealed experimentally. As a result, it has been verified that the smaller the transverse rupture strength and the higher the cutting speed, the variance of the tool life becomes the higher. Secondly the applicability of ceramic tools in machining steels has been discussed from the viewpoint of tool life. The results could reveal that the ceramic cutting tool would show a good cutting performance for high carbon steels and free machining steels in comparison with the carbide and TiC base cermet tools.

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A higher production rate of face-milling will be realized if a more abrasion resistant but less tough tool material can be used without breakage. For this purpose, titanium carbide cermet tool material is studied for utilization in steel face-milling. The main problem is to provide the effective land and the proper rake angle to the cutting edge. The land strengthens the cutting edge against the impact, while the proper positive radial rake recovers the sharpness which is lost by the land. Basic studies with single bladed cutters presented enough knowledge for the design of a TiC cermet cutter. According to the basic data, a multi-bladed TiC cermet throw-away cutter was designed and examined in an experimental run. The trial multi-bladed cutter proved a good utility of TiC cermet in steel face-milling.

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Tool life tests were conducted on nodular cast iron grades 100-70-03 and 80-60-03 with carbide and ceramic cutting tools. It was found that the cast iron cutting grade carbide wasc much superior to the steel cutting grade carbide from the standpoint of tool life and metal removal rate. With these carbides, crater wear developed at high speeds as well as flank wear in the entire speed range tested. Ceramic cutting tool had superior cutting performance. Its tool life was greater than that for the cast iron cutting grade carbide at high speeds. The slope of the tool life curve for a ceramic tool was much steeper than that for a carbide tool. Cutting performance for grade 80 nodular cast iron was not always better than that for grade 100 nodular cast iron, though grade 80 is a little softer than grade 100.

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Tool life tests were conducted on ferritic nodular cast iron (grade 60) with carbide and ceramic cutting tools, and the results were compared with those for pearlitic nodular cast iron (grades 80 and 100). It was found that the ribbon type flank build-up or smear protects the flank of carbide tool from flank wear. The tool life for ferritic nodular cast iron was much longer than that for pearlitic nodular cast iron. The cast iron cutting grade carbide showed better tool life than the steel cutting grade carbide when machining nodular cast irons. The tool life for ceramic tool was longer than that for carbides, especially at high speeds because of the steep slope of the tool life curve for the ceramic tool. The wear processes of carbide and ceramic tools were investigated together with the variation in tool forces due to flank wear.

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The effect of sliding speed on the boundary friction is studied under various conditions by measuring the friction and electrical contact resistance between the sliding metal surfaces. As the result of experiment, it is found that the friction-speed characteristic is affected by oiliness of lubricant. Addition of varying amounts of oleic acid to a spindle oil not only reduces the friction, but also very much affects the friction-speed characteristic. A thick film lubrication is set up even at low speeds, if a small percentage of oleic acid is added to a spindle oil. On the other hand, 100 percent oleic acid provides good boundary lubrication and reduces friction, but causes a considerable increase in the amount of wear.

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The wear properties of mono- and multi-molecular layers of barium stearate are studied under various conditions of loads and speeds. The wear properties of molecular layers are compared by measuring the increase of friction coefficient and the critical number of runs with the abrupt rise of friction coefficient during repetition of sliding over the same track. As the result of experiment, it is found that the critical number of runs is increased with the increase of film thickness or speed and the decrease of load, but there is a marked decrease in the durability of the film where the number of layers is more than about 10 molecular layers.

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