Fretting fatigue tests have been made about the effect of clamping pressure, p₀, and hardness of materials on the initiation of non-propagating cracks and also complete fracture under the conditions where the relative slip is fully controlled. The main results obtained are as follows. (1) Fretting fatigue strength based on the initiation of fatigue cracks, σ_w1, decreases linearly with the increase of p₀. (2) Fretting fatigue strength based on fracture, σ_w2, decreases gradually with the increase of contact pressure, and reaches a critical strength when p₀ is beyond a certain value. (3) These results in (1) and (2) are analogous to fatigue phenomena of notched specimens, when the stress concentration caused by fretting is considered. (4) When the relative slip of fretting is relatively large, σ_w1 is affected by the susceptibility of materials to wear.

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To clarify the effective factors for the crack propagation under varying load conditions, crack propagation is investigated using V-notched specimens and radial holed ones of 0.55% carbon steel and the following results are obtained. (1) The most important effective factor for the crack propagation under high-low type varying load condition is the essential increase of the stress at the crack tip for the opening of cracked surface caused by the repeated compressive plastic deformation. (2) In the case of steel specimens, there is no effect for the crack propagation under varying load condition caused by structural changing and it is also possible to estimate the crack propagation quantitatively considering the effect of crack opening. (3) It is also possible to estimate almost all the experimental results under varying load conditions qualitatively considering the effect of crack opening and existence of incubation period. (4) The effect of crack opening appears in the case of reversible stress condition but does not appear in the case of pulsating tension stress condition. This can be predicted by the calculation of the actual stress at the crack tip under varying load conditions.

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An elastic-plastic analysis of large deflection of axisymmetrically loaded circular plates is presented in this paper. Under the Kirchhoff-Love hypothesis, the incremental theory of plasticity together with the von Mises yield condition and the associated flow rule is adopted, and isotropic workhardening materials as well as elastic-perfectly plastic materials are treated. This is not an inherent limitation of the method. A numerical procedure with the finite difference approximation and the iteration technique is employed for the solution of the derived incremental basic equations of a two-point boundary value problem. Several results for various kinds of boundary condition and some values of plate thickness are given including the solutions of residual stress and strain for the first cycle of a loading-unloading process.

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We make a stress analysis on the above problem by means of a couple of stress functions with subsequent Fourier-Bessel expansion of the given loads on the boundary, and we obtain the same result as obtained by means of Hankel transformation. First, stress functions and their stress components are obtained for a general loading condition. Next we perform, for example, a numerical calculation and photoelastic experiment in a case similar to the condition of punching a thick plate. In the course of our calculation, we expand the part of hyperbolic functions of integrand contained within the stress functions expressed in infinite integrals by Taylor's law. Thus, integrating by terms, we obtain each stress component. By making use of the fact that the boundary conditions are satisfied asymptotically in the mode of a damped oscillation with an increase in terms, we are able to obtain an approximate solution sufficiently accurate for practical use.

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In this paper, the temperature distribution and the associated thermal stresses caused in a cylindrical shell subjected to a hot spot moving along a circumference with a constant speed, taking into consideration the cooling effect of the surrounding media and taking no such assumption as "quasi-stationary" or "shallow", are obtained by the general thermoelastic theory of a cylindrical shell introduced by the present author applying the Fourier transforms and the convolution theorem.

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B. Budiansky and P.P. Radkowski once presented a finite difference method for problems of unsymmetrical bending of axisymmetric shells. By putting the terms of inertia into the equilibrium equations in their paper, a numerical method for free vibration problems of axisymmetric shells of arbitrary forms is proposed in this study, and the validity of this method is checked for shells of various kinds-circular plates, cylindrical shells, conical shells, spherical shells, and shells of nuclear vessels.

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On the superficial Rockwell hardness test which is becoming more popular, the authors have reported the effect of various errors on the T scale hardness reading in the first report. In this report, the effects of errors in the preliminary load W₁ kg, the total load W₂ kg, the tip radius R mm of the diamond indenter and the included angle θ rad. on the N scale hardness reading H_RN are analytically clarified by using the extended Meyer's law and the law of similarity. As an example, the following equation is obtained for a medium hardness specimen (30≤H_R15N≤70), ΔH_R30N={139.2-9.486×10^-3(100-H_R30N)²}ΔR+1.734(65.40-H_R30N)Δθ+0.6656×10^-3(100-H_R30N)²ΔW₁-2.527×10^-2(100-H_R30N)ΔW₂ A good agreement is observed between the analytical results and the experimental ones. In addition, the authors' proposal for establishing a tentative JIS (Japanese Industrial Standard) is made.

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This paper deals with the optimization of a nuclear reactor system with consideration of neutron flux uncertainty. Using the average and two kinds of variance of neutron flux which are obtained by means of modal analysis technique, the author has formulated the maximization of average power output under the condition to make the uncertainty of neutron flux as small as possible and presented Mode Optimization Technique for the optimization problem of a distributive system. Numerical results show that the optimal distribution of average neutron flux is not always flat when we consider the uncertainty of neutron flux as a loss of safety or reliability of a nuclear reactor. The author finally points out some problems concerning the performance index for this statistical optimization of a nuclear reactor system.

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It is well known that the pneumatic-hydraulic control system can improve the incomplete points of hydraulic system in automatic contour-following machines. However, the characteristics of a pneumatic servomechanism is susceptible to influences of various frictions, owing to its small operational force. In this paper, the effects of the viscous friction in the pipe and the solid friction of the output element are examined theoretically and experimentally. The critical solid friction that does not have a harmful influence upon the dynamic characteristics of the pneumatic servomechanism is introduced as a function of the properties of the pneumatic mechanism and working conditions. On the basis of these results, the concrete and practical means for improvement of the characteristics of a pneumatic servomechanism are discussed.

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The viscoelastic properties which would be important in the unsteady flow fields in the Lagrangian sense are studied converging and diverging flows in a V-shaped duct. When the viscoelastic fluid flows slowly in the duct, the velocity profile can be approximated by that of a purely viscous, non-Newtonian fluid, applying the Denn model as the constitutive equation; and the differential equation for the velocity profile can be solved by a perturbation method regarding the "power law index" as a perturbation parameter. Using the velocity profile obtained, the stresses in the duct are analyzed. Results are in good agreement with the experimental results performed by Adams et al.

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A new transient measuring method of thermal diffusivity by continuous heating of a slab-like specimen to obtain the temperature dependence of thermal diffusivity covering a wide temperature range in a short time, is investigated. The principle is based on the solution of equation of linear heat conduction and the thermal diffusivity is determined from the temperature response at the center face of the specimen heated continuously from both surfaces. The measuring conditions are determined by theoretical analysis. By comparing the linear solutions of the measuring principle with the non-linear solutions of the measurement obtained analytically or numerically, the heating conditions of the specimens under which the linear principle is satisfied within required accuracies are determined. Results of testing polyethylene up to the softening temperature with an apparatus based on the above conditions are shown.

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The effects of various parameters on the ion currents to Langmuir-type cylindrical probes of Pt or Pt/Rh alloy were studied experimentally. First of all, in very low ion density flows of pure combustion gases, the effects of the potential and the dimensions of the probe on the ion current were examined. In the case, an apparent increase in ion current due to thermal emission of electrons occurred when the surface temperature of a probe containing Rh became higher than 1 900°K. The sheath thickness around a probe seemed to be larger than 0.5 mm. Furthermore, experiments were conducted in combustion gas flows, the ion densities of which were increased with the addition of potassium. Besides the effects of the potential and the dimensions of the probe, those of the flow velocity and the ion density of the gas on the ion current were examined, and an empirical equation for the ion current was obtained.

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The experimental results of static characteristics and dynamic behavior of frictional pressure drop in a long steam generating tube have been presented. The test section was made of 9.6 mm inside diameter and 42.74 m length boiler tube and was heated uniformly by alternating current. The static characteristics of the pressure drop expressed in dimensionless form agree well with the theoretical result decribed in the previous report and also with Thom's correlation. The experimental results of the dynamic behavior of the pressure drop with the change of inlet flow rates agree with theoretical results, and that with the change of heat input approximately agree with theoretical results except in the initial period. The experimental values of the time constants have been discussed.

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