The diffraction of steady-state stress waves from arbitrary shaped inclusions in an infinite medium is described by means of a set of displacement potentials. Unlike some other formulations, this procedure can deal with boundaries of arbitrary shape. The solution of the integral equations yields a potential function at the interface which is employed to derive the stresses by surface integration. The formulation is presented for two-dimensional case. The inclusion is fixed in space which is void or rigid body for incident SH wave and is rigid body for incident P and SV waves. The resulting stress field was found to be in excellent agreement with that obtained from a series solution of diffraction of a plane harmonic wave from a rigid circular cylinder. solutions of other two-dimensional configurations of interest involving discontinuities are also presented.

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A method of optimum design for maximizing the buckling load of an elastic-plastic column of given volume, length, and material is presented. The column material is assumed to obey Ramberg-Osgood's deformation law and the buckling load is computed by means of the finite element method taking account of the tangent modulus theory. Rosen's gradient projection method is used for determining the optimum shape. Numerical results obtained for a simply supported column with similar cross section are shown to be in reasonably good agreement with the analytical solution proposed in a previous paper. As for new treated examples of columns with other cross sections and boundary conditions, it also seems that reasonable solutions are obtainable by the proposed method. Furthermore, we treat the problems including the constraint on a lower bound of the cross sectional areas of columns.

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The three dimensional analysis of stress and strain in linear visco-elastic bodies is considered when the loading is impulsive. It is shown that removal of the time variable by the applying the Laplace transformation enables a solution to be obtained in terms of an associated linear elasto-dynamic problem. Thus the analytical methods based on the stress functions can be utilized in visco-elastic analysis. As an example, the mixed boundary value problem of a semi-infinite body subjected to impulsive torsion on its surface by a rigid cylinder is analyzed assuming the material to be a 3-parameter standard solid model. Stress, displacement and stress intensity factor are shown for the cases of a given rotational angle and a given torque of the cylinder.

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The finite element method for plastic deformation of porous metals has been developed for the analysis of forming of sintered metal; based on the plasticity equations for porous metals and the upper bound theorem, a velocity field which minimizes the power is obtained. The stress components are calculated by the use of the incremental strain theory. Upsetting of cylindrical billets with smooth or rough tools and indentation of a flat punch into a cylindrical billet in a die are treated. The calculated load and the distributions of density and stress components show good agreements with experimental results.

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The rigid-plastic finite element method based on the plasticity equation for porous metals has been extended and applied for the analysis of plastic deformation of ordinary pore-free metals. The relative density is assumed to be very close 100%, eg. 99.5% or 99.95% in the calculation. The stress and strain states can be calculated with this method up to large deformation. Upsetting of a cylindrical billet with grooved dies and compression of square and rectangular thin plates with flat dies without lubrication are analysed. The analytical results of stress, load and deformed shape show good agreements with experimental results.

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Discharge coefficients, including general flow rate characteristics when the gradient of a tapered tube is large, of float-area-type flow meters are generally discussed. It is experimentally pointed out that the discharge coefficients became constant when a float, having the small length of the maximum diameter part of the float and having 180° vertex angle of the cone portions upstream of the maximum diameter part of the float, and a particular tapered tube having the gradient k=0.545 are employed. When employing such a combination of the float and the tapered tube, a semi-empirical formula to predict the flow rate characteristics is obtained and the limits of applicability of the formula are experimentally explained. Finally, a float-are-type flow meter having linear relations between the flow rate and the position of the float is manufactured.

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In the analysis of an accelerated two-phase flow, the phase change in thermal equilibrium condition, wall friction, interphase friction caused by the difference between two velocities and the entropy increase are considered. Some numerical calculations are made for the conditions of Ogasawara's experiments of a steam-water critical flow from a long constant cross-section pipe. The numerical results are in good agreement with the experimental ones, i.e. the pressure gradient close to the exit plane of the test pipe and the critical flow rates. Further numerical results show that, of the total pressure drop caused by friction and acceleration, the proportion attributable to friction approaches zero in the condition of a critical flow at the exit plane and that the critical flow rate is not determined simply in terms of pressure and quality at the critical flow condition but in the approaching process to critical flow condition.

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The effects of a flow obstacle set in an air-water two-phase upward flow system are examined on the minimum film thickness occurring upstream and downstream of the obstacle. The obstacles used are several rings different in length and gap between the outer surface of the ring and the inner surface of the tube. Instantaneous flow appearance near the obstacle strongly depends upon the net opening ratio of the obstacle including the gap, which obviously affects the magnitude of minimum film thickness. With the same gap, the reverse flow through gap is pronounced with an increasing length of the obstacle. This leads to an increase of minimum film thickness upstream of the obstacle. The effects of the various parameters of obstacle such as shape, size and gap are summarized using all the experimental results so far obtained.

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In a gas-liquid two-phase upward flow system with a flow obstacle, it has been reported in previous papers, the water film thickness below the obstacle is extremely reduced due to a drainage, which is caused by the prevention of a reverse flow of water film surrounding a gas slug. This paper presents an experimental and analytical approach to understand the film thinning mechanism during the drainage. A physical background for the formation of the minimum film thickness is also provided, and the film thinning effect due to drainage is suggested to be principal cause producing dry patch under diabatic condition.

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The application limit of the cavity model for the inlet or exhaust system was investigated by comparison between predictions and experiments of volumetric efficiency in 1st report. In this paper, the application limit was examined by comparison of calculations; the predictions obtained by an unsteady model including unsteady phenomena in the inlet or exhaust manifold and those of the cavity model. Then the limit of the cavity model in throttle degree, inlet or exhaust manifold length and engine speed was clarified and it agreed with that acquired from experiments. Furthermore, this cavity model was re-confirmed to be valid for the analysis of the gas exchange process under city-driving conditions.

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The free in-plane vibration of a slender arc of varying cross-section is analyzed by use of the spline interpolation technique. For this purpose, with the arc divided into small elements, the in-plane displacement of each element is expressed by a spline function of 7 degrees with unknown coefficients. The displacement is obtained by determining these coefficients such that the spline function satisfies the equation of motion of the arc at each dividing point and also satisfies the boundary conditions at both ends. In this paper, the tangential displacement of the arc is chosen as the variable to be solved from a sixth-order differential equation, from which the frequency equation is derived. The method is applied to free-clamped arcs with linearly, parabolically and exponentially varying cross-sections; the natural frequencies and the mode shapes of the arcs are calculated numerically and the effects of the varying cross-section on them are studied.

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Three dimensional numerical analysis for a spherical foil bearing scanning against a plane foil is performed, under the assumption that the foil is perfectry flexible and deforms as a set of strings stretched in the tension direction. The tends of pressure distribution, foil deformation, spacing distribution and minimum spacing are discussed in connection with the various bearing parameters such as bearing dimension, scanning angle and relative position between bearing and foil.

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The conventional analyses based on the classical Reynolds equation are incomplete to get five predictions of the dynamic characteristics of externally pressurized gas bearings. This seems to be attributed to the fact that the Reynolds equation ignores entirely the inertia forces of the gas-film. This paper process modified Reynolds equations, which are derived by averaging out the inertia forces in Navier-Stokes equations across the film thickness, and their adequate boundary conditions, in order to determine the influence of the inertia forces on the dynamic characteristics such as the whirl instability and the squeeze damping.

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In order to clarify the effects of hardness on the surface durability and surface failure, fatigue tests on various heat-treated steel rollers were carried out under sliding rolling contact condition. The surface failure modes could be estimated by the values of the maximum amplitudes A_max of the ratios of normal stress on the surface in circumferential direction of roller and of orthogonal shear stress under the surface to Vickers hardness and the peak amplitude A_{peak b} of the ratio of orthogonal shear stress to Vickers hardness which occurs at case-core boundary. The relation between the surface durability together with the surface failure mechanism and the hardness distribution could be clarified by calculating the amplitudes A_max and A_{peak b} and by Vickers hardness at the depth of these amplitudes. From the standpoint of design, the surface durability of a machine element can be evaluated from the equation A_max=0.051 or A_{peak b}=0.035 when the hardness and residual stress distributions of the machine element are known.

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In order to clarify the effect of specific sliding on surface durability of case-hardened gears in relation to temperature rise, the case-hardened chromium molybdenum steel rollers were tested in the range of specific sliding of 0 to -91 percent under two rotating speeds of 1800 and 5400 rpm by using a rolling contact fatigue testing machine. The experimental results on the surface durability and the surface failure of these rollers were discussed considering the temperature rise of roller. and it was suggested that in determining the surface durability of the case-hardened gears the temperature rise can not be neglected on the severe operating condition.

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The surface durability of the H_B≈340 hobbed gears made of a leaded free-cutting steel was investigated by using a power circulating-type gear tester. And, the surface durability of the honed gears was studied. It is found that the hobbed gears made of a leaded free-cutting steel are longer in pitting life than ones of a usual steel, and that the honed gears have a much longer pitting life. The main reason for these results is that the initial tooth surface of leaded free-cutting steel gears is smoother than that of usual steel gears under the same hobbing conditions, and that the honed gears have a much smoother surface. Therefore, these gear tests show that the surface durability of the H_B≈340 steel is improved by the smoother surface, and this confirms the results obtained in the roller tests in the previous paper (1st report)⁽¹⁾.

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