In order to study the effects of the mean plastic strain and the stress factor on the cumulative damage rule, low-cycle fatigue tests were carried out on 0.38 % C steel, austenitic stainless steel and heavily cold-drawn copper. It was found that the fatigue life under arbitrarily varying plastic strain conditions could be estimated by combination of the linear cumulative damage rule in terms of the plastic strain range-- pair and the effect of the reduction of the fracture ductility caused by the mean plastic strain. Even if the above mentioned effect of mean plastic strain was considered, measurable deviations from the linear damage rule were observed, particularly on the materials which tend to work-harden or -soften to a high degree. However, such deviations were found to be reduced by allowing for the difference in the stress behavior between variable and constant plastic strain amplitude tests.

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The dynamic stress concentration around circular discontinuities in an infinitely extended elastic plate, during passage of a cylindrical dilatation wave of which strength varies harmonically in time, is discussed. When the wave source is apart infinitely from discontinuities, the resulting dynamic stress concentration factor coincides with the result for a plane wave incidence. The influence of the proximity of wave source to discontinuities and the interference effect are studied in detail numerically for the cases of circular holes which exist in a finite domain. According to the results, (1) the maximum stress concentration factor is higher for greater incident wave curvature and (2) the maximum dynamic stress concentration factor approaches to a value which is higher than that of single hole, as the radius ratio between the holes becomes greater, when the radii of the curvature and of the reference hole are kept constant.

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In this paper, a technique to obtain an optimum strength shape is proposed by applying an automated design system. The main process of this technique is that at the first step a fundamental shape, which satisfies the design conditions, is made ; at the second step the superiority or inferiority of the shape is judged according to the stress distributions obtained by using the F.E.M. ; and more the shape is corrected at the final step. Particularly, at the final step the correction of shape is made by the method of changing the finite elements used by the F.E.M. into the optimum shapes. If these steps are repeated, the optimum shape will be obtained. Next, the above mentioned technique is applied to determine an optimum strength shape of a dam under water pressure.

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A nonlinear multidegree-of-freedom vibratory system is called tuned to internal resonance if several of the corresponding natural frequencies are integral multiples of the lower natural frequencies. In the paper is taken up a typical case of a two-degree-of-freedom system with internal resonance with a higher natural frequency twice the lower natural frequency, having nonlinear spring characteristic of second and third order polynomials of the displacements. Steady forced vibrations are investigated in the vicinity of the lower resonance point of the system. The theoretical analysis indicates that the second order harmonic occurs strongly in addition to the harmonic oscillation with a frequency equal to the excitation frequency; and that almost periodic oscillations occur in a certain region of the excitation frequency. The results of the theoretical analysis are shown to agree with those of an analog-computer analysis.

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For nonlinear programing problems with equality constraints, Powell has proposed a new sequential unconstrained method. This paper extends the method to the optimal control problems with both equality and inequality constraints. The following results are obtained. 1. The convergence of the method is proved under a few assumptions. 2. The optimal solution is obtained as finite values of parameters. Therefore, numerical difficulties can be avoided in the minimization of the penalty function. 3. The optimal values of parameters are closely related to the optimal Lagrange multipliers. 4. The convergence to the optimal solution can be forced to be rapid by increasing the parameters corresponding to penalty coefficients. Finally, The efficiency and the accuracy of this method are investigated on a problem.

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Subsonic compressible potential flow in a centrifugal impeller can be analyzed by using a pseudo-analytic function. In this paper, the foregoing method has been applied to the calculations of nonviscous and compressible fluid flows in a two-dimensional centrifugal impeller with thin logarithmic spiral vanes, and influences of compressibility on the velocity, pressure and density distributions along the vane surfaces under the condition of shokless entry have been calculated. Furthermore, heads and flow rates of the impeller in case of shockless entry have been shown charts.

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Measurements of velocity distribution in three turbulent boundary layers on a circular cylinder spinning in axial flows, two with adverse pressure gradients and one with favorable pressure gradient, are presented and discussed. The peripheral shear-stress distribution in the boundary layer is calculated numerically from measured mean velocity profiles. On the basis of them near the wall, the law of the wall is considered. A formula for the logarithmic velocity distribution in the peripheral direction is deduced on the usual assumption that the wall layer and the outer layer overlap each other. This expression succeeds in depicting the measured velocity profiles. A Richardson number describing the effect of rotation or streamline curvature on a turbulent flow is used in an attempt to clarify the character of these flows; the changes in the constants in the logarithmic formula for the velocity distribution are represented in terms of the Richardson number.

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The flow region round a circular cylinder with tangential injection of air immersed in a uniform flow is divided into four parts that are parts of curved wall-jet, turbulent boundary layer, laminar boundary layer and wake. The characteristics of each part are calculated by the authors' method on the curved wall-jet, Furuya's method on the turbulent boundary layer and Thwaites' method on the laminar boundary layer. Based upon these characteristics obtained, the aerodynamic forces are calculated and compared with the authors' experiment. It was found that, when one parameter among the lift coefficient, the drag coefficient, the front stagnation-point, the separation point of jet and the base-pressure coefficient was given, the rest of them are uniquely determined.

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Mean velocity and turbulence together with pressure distributions of jets issuing from ring nozzles with various openings, and spreading out radially over a flat smooth plate were studied. By changing the diameter and width of nozzles and discharge velocity, the flow pattern was measured. Flow field in the main region has been divided into two regions at the point of maximum flow velocity, that is, inner layer near the wall and outer layer away from the wall. Velocity profile in the inner layer is similar to Glauert's curve obtained for a radial wall jet, and the one in the outer layer agrees well with Goertler's curve for a two-dimensional free jet. Maximum flow velocity decays and growth of the jet half width lie on a single curve by making use of an equivalent nozzle width which contains the diameter and width of the nozzle.

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Frequency characteristics of fundamental hydraulic circuits which were composed of a hydraulic motor and a spool valve were studied. Analyses were carried out on : (i) a linear method, (ii) an approximate method using a non-linear equation with non-linear characteristics of the spool valve taken into account, (iii) the case where angular acceleration was neglected because of the slow rotation of the hydraulic motor and (iv) a numerical solution for the non-linear equation ; and the calculated results were compared with the experimental results. It was pointed out that the test results showed good agreement with the analytical solution of the linearized equation with respect to amplitude and phase of the hydraulic motor, whereas the average angular velocity of the motor decreased with an increasing frequency of the spool valve under the influence of higher harmonics caused by non-linearity of the spool valve.

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It is found experimentally that the lubricating oils, with high molecular weight polymers, indicate the composite flow characteristics involving pseudo-plastic and dilatant behavior. Applying a polynomial expression for such non-Newtonian characteristics, a modified Reynolds equation is derived, to obtain the pressure distribution and the load capacity of journal bearings. Comparing with experiments, the physical meanings of the composite flow characteristics are made clear. The effects on the bearing performance are discussed, by introducing a "ratio of nonlinearity" and a "rate of nonlinear influence".

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In order to clarify the surface durability of the surface hardened steels and the optimum design condition of the surface hardened gears, the carburized and hardened steel rollers were tested with a rolling contact fatigue testing machine. Consequently, it was made clear that there is an optimum case depth for the surface durability and that the crack initiation depth of spalling coincides quite well with the depth where the amplitude of the ratio of orthogonal shear stress to Vickers hardness becomes maximum. By using these test results, the authors introduced a tentative method for calculating the optimum case depth for surface durability of roller pairs which had various relative radii of curvature. And this calculation method was successfully discussed with the practical case-hardened gears.

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The authors have published a theoretical calculating formula of cutting force in orthogonal wood cutting accompanied with front split⁽¹⁾. It was obtained by applying the theories of beam on elastic foundation and linear fracture mechanics. In this paper, they analize the orthogonal cutting accompanied with front split, down split, side crack and lateral crack, and introduce the theoretical calculating formulas. Furthermore, they confirm by the experiments that their formulas are sufficiently applicable for practical use.

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