The effect of modified ausforming on fatigue properties of_Ni-Cr and Ni-Cr-Mo steels has been studied. These steels were rolled to reduce the thickness tO 30, 54 and 72 % in the temperature range between 880°C and 700°C, and cooled to form martensite. Their fatigue properties under alternate bending stress were then compared with those of the conventionally treated specimen after tempering at 3OO°C or 6O0°C for 1 hour. Fatigue limit increased approximately linearly with the reduction up to 54 % and the increase of fatigue limit amounted to about 0.17 - 0.22 kg/mm² per 1 % reduction. The maximum improvement of fatigue limit was 39 % and fatigue life was prolonged by the process. Endurance ratio was then improved by modified ausfoming. Moreover, modified ausforming restrained the intergranular fracture of these steels after low temperature tempering. Matallographic observations revealed that the modified-ausformed specimen kept refined subgrains even after higher temperature tempering. It was found that the refinement of subgrains was an important factor in the improvement of fatigue strength of these steels.

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A technique to obtain an optimum layout of structural continua which gives minimum weight design is proposed by using the finite element method (FEM). In this FEM, the triangular elements of structural continua consist of orthogonally crossing members distributing uniformly and continuously. To arrange these members in the optimum directions, Davidon-Fletcher-Powell's method is adopted and the weight of the structural continua is minimized. The optimum layout of the frameworks is determined from the arrangement of the truss members in the finite element. The technique is applied to determine the Michell structures and the results are compared with the absolute optima.

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Transient response of an infinite elastic solid to a moving point load is considered. An analytical solution procedure is presented for solving a three dimensional problem of the moving load. The load motion is largely arbitrary. The subject problem is reduced to a simple consideration on "Arrival Time Function, " defined in this paper. Three typical ceses of the load motion, stationary, uniformly moving and accelerating loads, are discussed in detail. It is shown that analyses of waves and responses are carried out simultaneously by considering the behaviour of the Arrival Time Function and that extremum of the Arrival Time Function gives characteristic wave fronts such as shock waves ( leading waves ).

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The principles of virtual work for two elasto-impact bodies in a contact state and a separate one are required to formulate the finite element method (FEM) for the behavior of alternation between contact and separation like that of mating gears. The principle and its subsidiary conditions for two separate bodies are obtained by introducing a displacement vector corresponding to clearance and regarding two bodies as a body, and they are used to formulate the FEM for two bodies. Two-dimensional behaviors for longitudinal impact of two rods are investigated to verify the FEM for two elasto-impact bodies in a contact state and a separate one. The results by the FEM agree well with those by the theory of propagation of one-dimensional elastic stress wave. The use of the subsidiary conditions for two separate bodies makes it much easier to discriminate between contact and separation, and it is possible to decrease the executing time for computation. Some remarks are stated in Sec.5.

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The present study describes an experimental investigation on the flow around a circular cylinder vertically mounted on a plane wall along which a turbulent boundary layer is fully developed. For the purpose of decreasing the number of geometrical parameters, the height and diameter of the cylinder are taken to be equal in the present case. Measurements were made of the pressure distributions and the drag forces acting on the cylinder. The pressure forces of the circular cylinders were experimentally correlated with the mean dynamic pressure of the turbulent boundary layer, which was defined as q=∫_o¹(u/U₀)²d(y/h). Drag force coefficients were found to be expressed as a linear function of the mean dynamic pressure included in the turbulent boundary layer described above.

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The purpose of this investigation is to give a theoretical explanation for the vortex breakdown phenomena of a swirling flow in a pipe. In the proposed mathematical model, the mean flow is assumed to be a rigidly rotating one (constant angular velocity) with uniform axial velocity. It is found that the internal wave (inertial wave), which may occur in the swirling flow, plays a significalt role in the breakdown phenomena. An integer parameter in the formula describing the internal wave, has a close relation with the structural mode of breakdown. Thus, the first three values of the parameter, 0, 1, 2, correspond to the typical three observed types of breakdown, axisymmetric, spiral, and double helix, respectively. The present study concerns only time-independent types of these phenomena. The time-dependent ones will be discussed in another paper.

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The nonlinear stability of a thin liquid layer flowing down an inclined plane which is oscillating in a direction perpendicular to its surface is analyzed using the power series of amplitude in the form of the Fourier series with the coefficients depending on the time. Although the growth rate of the disturbances is influenced by the oscillation of the plane, its influence vanishes on an average. In the flow down an oscillating plane, the oscillation is synchronous and there is an equilibrium state with time-periodic amplitude and phase velocity. The magnitude of the time variation of the amplitude and the phase velocity increases as the amplitude of the oscillation of the plane increases and as the frequency decreases. However, taking the average, the equilibrium amplitude in the oscillating plane is smaller than that in the fixed plane. The flow is stabilized by the oscillating plane.

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A steady laminar flow of an incompressible Newtonian fluid in the inlet region of rectangular ducts is analyzed by the integral method. The main results obtained are as follows. (1) The axial pressure variation agrees better with experimental data than theoretical results by other methods. (2) The development of velocity profile agrees somewhat with experimental data. (3) The additional pressure drop and the inlet length can be predicted with satisfactory accuracy.

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The drag of a flow through uniformly dispersed spherical particles is predicted. The results are useful for studying the dynamics of multiphase flows containing dispersed particles and fluidized beds. In analyzing the flow, the many body effect on the drag is considered by utilizing the simple cell model method. The basic equation of motion of fluid is simplified by Oseen's approximation. The drag coefficient is computed as a function of the volume fraction of particle phase and of the Reynolds' number of flow.

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An ionized gas particle created by spark discharge between electrodes has a density different from that of the surrounding gas. This difference of densities causes errors in measuring the velocity when a spark tracer method is applied to an accelerated flow. In this paper, assuming a simple flow model, the error associated with the difference of densities of tracer and surrounding gas has been calculated for an unsteady accelerated flow induced by an expansion fan in a shock tube and for a steady accelerated flow in a subsonic nozzle. The error increases with time in the latter case, but in the former case it becomes maximum at a certain time. The calculated results qualitatively agree well with the experimental values measured in a driver section of a shock tube. Furthermore, the relation between the error and the magnitude of acceleration has been discussed.

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Experimental studies on converging detonations have been performed aiming at application to high-power pulse lasers and production of hightemperature plasmas. Viewing that the duration time of the detonation is relatively short (< 10 μs) at the converging point, spectroscopic measurements have often been used as diagnostic techniques. In the present study, the emission of CN violet bands from a converging point was analyzed using a microdensitometer. In order to determine the temperature at the converging point of a detonation, a method of matching the entire emission spectra was utilized. The anticipated emission spectra of the observed band can be theoretically calculated with a combination of the gasdynamic quantities, assuming Boltzmann distributions for rotational, vibrational and electronic energy levels. After several trial-and-error processes, the best fit was obtained for T = 11 000 K, N = 7.5 x 10¹⁶/cc and the Lorentian broadening half-width W_l = 0.003 nm : The detonation was produced using equi-molar oxyacetylene mixtures at P₁ = 60 Torr (8.0 x 10³ Pa) and T₁ = room temperature in an 80-cm-dia. double-disc-type detonation chamber. It was found, as a result, that unavoidable doppler broadening inherent to high temperature experiments and a wide slit function could be handled with no essential difficulty and a correct rotational/vibrational temperature could be obtained.

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The objective of the present work is to obtain information on the formation and the decomposition of the soot corresponding to the combustion condition. The quantity of combustion air and dilution of the fuel with N₂ gas are changed in a wide range and the quantity of fuel is constant in the experiment. The main results are as follows. The profile of soot concentration can be divided into two distinct zones, in the first of which the soot is formed and in the second of which soot combustion occurs. The soot formation occurs very easily with rich fuel and in the presence of some unburned hydrocarbons such as CH₄, C₂H₄ C₂H₆ and C₂H₂, there is no remarkable difference in both flames (Φ=0.6, 1.4). However, combustion of soot is remarkably different because of entrainment of air. With regard to effect of dilution with N₂ gas, the soot formation rate is greatly suppressed in the formation zone, as the dilution ratio with N₂ gas increases.

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The quenching distances of mixtures of methane and hydrogen with air are determined. The quenching distances are given as a function of hydrogen percentage of the hydrogen-methane mixtures, excess air ratio and pressure of unburnt gas. It is observed that the flame quenching phenomenon has probability nature at the region where the distance of the two discs approaches the quenching distance. Futhermore, the correlation of stretch factor and quenching distances is derived and the relation of hydrocarbon emission levels of piston engines and quenching distances is discussed.

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To clarify in more details the effect of swirl on the engine performance, a continuous alteration of swirl characteristics was made during the operation of engine by making use of the "variable angle swirler" installed around the scavenging ports of a uniflow scavenging engine. On the basis of the results obtained from the steady flow measurements in the cylinder, the effect of the swirl was mainly discussed in relation to the fuel distribution characteristics by inspecting it through the fuel consumption and the exhaust smoke. As the result of experiments, the difference between the optimum swirls for the exhaust smoke and for the fuel consumption, the relation between the geometrical configuration of injection jets and the swirling motion of air, the effects of the load and the shape of the combustion chamber on the optimum swirl, etc. were clarified.

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In this paper, we show a method for solving the free out-plane vibrations of a uniform curved bar of which the center line is a plane curve considering the effects of the bending, the torsion, the shear deformation and the rotatory inertia of the bar. We solve the equations of vibration exactly by a series solution. As numerical examples, we obtain natural frequencies and mode shapes of symmetric catenary, parabola and cycloid curved bars with clamped ends. The numerical results by the present analysis are compared with the ones by the classical theory and the effects of the shear deformation and the rotatory inertia are clarified.

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Various types of nonlinear forced oscillations are expected to occur in a beam subjected to harmonic excitation. The present paper concerns among others the summed and differential harmonic oscillations. Theoretical as well as experimental analyses are carried out for the oscillations. The theoretical analysis shows that only the summed type can occur in a beam, and that a constant term is necessary in the excitation for the oscillations to occur. The theoretical analysis also reveals that the transition to the state in which only the harmonic oscillation occurs, is made continuously by increasing the excitation frequency. The experimental analysis verifies the results of the theoretical analysis.

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As regards a balancing method for a flexible rotor, a modal-least squares balancing method is derived, which has both features of the modal balancing and least squares balancing methods. The effect of each correction mass, which is obtained by the above method, on the vibration is physically clarified. Even if the influence coefficients contain errors initially, they are easily corrected by applying the above method, and a good balancing result is then obtained. It is described by some numerical simulations how the above method is effective for the balancing of the flexible rotor.

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On a running machine, the band frequency components of vibration at each portion of the external surfaces are classified into two categories. One is a stationary component and the other is a non-stationary one. This paper describes an approach to estimation of the noise emitted by each of them. In the former case, assuming that the vibrating plate consists of many minute elements and each of them vibrates in a simple harmonic motion, the sound pressure levels can be estimated by summing up all the sound pressures radiated from each minute source. In the latter case, the radiation efficiency which is defined as a coupling co-efficient between surface vibration and radiated acoustic power can be calculated as a function of density, thickness and stiffness of each plate. The acoustic power levels estimated by using this radiation efficiency and the mean square average of vibration acceleration have been found to be in good agreement with those obtained from the experiment.

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A dynamic absorber which contains two fixed side magnets, and an absorber magnet (absorber mass) ' is called a magnetic dynamic absorber (M.D.). The absorber magnet is located between the side magnets and floats along the axis between them, each working on each other's magnetic forces. As the vibrating system (principal mass) is attached on a damped magnetic dynamic absorber and subjected to an external periodic force, the amplitude of the principal mass can be decreased. In this paper, the vertical and horizontal vibrations of a periodically forced vibrating system with M.D. are analyzed. Especially the most favorable state in the principal mass which is worked by M.D. is discussed and the values of its amplitude in the most favorable state are solved. Then the absorber factors of M.D. which depend on the condition are obtained and these are compared with the experimental results.

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An automatic control system for maintaining the working face stability of a "soil pressure shield machine" has been developed. This machine is particularly suited to tunnel constructions under unstable grounds. At first, the stability conditions and mathematical modelling of the working face are discussed. It is found that the best method of control is to correct the error in soil amount by soil pressure signals. An analogue simulation model for the total system is made, and system response characteristics are analyzed for various values of each parameter. An actual system is designed and manufactured according to the results of the above simulation, and is proved to have the expected performance. Putting its field operation data into the abovementioned simulation model, the model is verified to be reasonable and the values of the unknown constants are quantitatively estimated.

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This paper describes a method of the synthesis of a plane fourbar mechanism which generates a curve as an envelope of a straight line fixed on the coupler link. The envelope is expressed as the locus of the point of intersection of a straight line and its perpendicular passing through the instantaneous center of the coupler link. The proportion of the mechanism is determined by solving the equations for these two lines as well as the loop-closure equation of the mechanism. The generated curve touches the ideal curve at 2 or 3 prescribed points, or 5 tangents of the ideal curve, and its normal error may be reasonably small in a widely specified domain. Meanwhile, the error of the generated curve becomes quite small in the neighborhood of the prescribed points when the higher-order derivatives of the equation of the straight line are adopted also as the equations of synthesis.

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This paper describes a precise curve generation based on the envelope of a straight line fixed on the coupler link of a plane four-bar mechanism. The asymptotes, points of inflection and cusps of the envelope are discussed both analytically and graphically, and the normal deviation of the envelope due to small changes of kinematic parameters is formulated. Moreover, the tool-driving condition is analyzed for the generation of surfaces by means of a milling cutter or grinding wheel whose center reciprocates on the coupler link.

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The root stresses of thin rim spur gears are investigated by means of the two-dimensiona1 finite element method (FEM) with triangular elements. The effects of boundary constraints for gear models and of adjacent teeth on the root stress distribution are discussed. The gear tooth model with a single tooth is shown to be available for a sufficiently precise evaluation of root stresses. A suitable rim thickness of gear model for the stress analysis by FEM is proposed. The true root stresses are computed and measured for gears of different rim thicknesses. The true stresses computed by FEM are in a fairly good agreement with measured ones. On the basis of these investigations the effects of rim thickness on the root stresses and on the critical sections in thin rim spur gears are also discussed.

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The limiting load for scoring was mainly investigated by means of the FZG spur gear testing machine. As base oil we used five kinds of oil and as anti-wear agent we used Zn-dialkyl-dithiophosphate (ZDTP), which is one commonly used. We found out the effects of viscosity of base oil and the concentration of anti-wear agent on the limiting load for scoring. Furthermore we found out characteristic tendencies of 4-ball test, roller test and crossed helical gear test. All test results were compared with each other. Besides specific wear V_s as a function of concentration of ZDTP was also investigated with various viscosities of base oils. Here we found out an optimum concentration of ZDTP, which causes a minimum specific wear V_s.

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The study on the computer aided design system for machine tool structures has made a startling progress. The present computing methods cannot be applied to the absolute estimation of structural rigidity, only based on the information from engineering drawings, because there are some problems in the determination of the mathematical model. In future, it is, therefore, necessary to estimate absolutely and quantitatively the rigidity of a machine tool as a whole, using the information from engineering drawings. There are, however, two difficult aspects to the problems; one is a reasonable procedure for the deter-mination of the mathematical model to analyse the characteristics of the structural components, and the other is a procedure concerning how to incorporate the joint characteristics into the mathematical model. In this paper, therefore, a new reasonable procedure to determine the mathematical model using the rigidity distribution diagram for the basic structural component was proposed, and as an example, the static stiffness of the column of a floor type horizontal boring machine was analysed and the propriety of the procedure was certified.

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