The fatigue limits, σw₁ and σw₂, which are critical stresses for initiation and propagation of stage 2 cracks respectively, were compared among annealed, quenched and quench aged steels. To examine the effect of heat treatment on the fatigue life, crack propagation rate, d(2a)/dN, was measured at a stress above σw₂. The contribution of quenching and quench ageing to the increase in the fatigue limits is greater for σw₂ than for σw₁, and the relationship, ασw₁≃σw₀, is kept independent of the heat treatments, where σw₀ is the fatigue limit of unnotched specimens. Therefore, the notch sensitivity factor, ( σw₀/σw₂-1)/(α-1), is reduced by both treatments. The strengthening effect is more remarkable with quench aged steel than with quenched steel. At higher ΔK level, d(2 )/dN is independent of the heat treatment, and is correlated with the streas intensity factor ΔK. The increase in the fatigue life by quenching and quench ageing is due to the decrease in d(2a)/dN at lower ΔK level.

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In the present paper we describe the impact torsional stress of a circular bar supported horizontally and subjected to impact torsion, when a cross pin attached to the end of it was struck by a dropped bar. Stresses obtained by experiments were in good agreement with those by one dimensional theory except for the short time after the impact. Therefore it was found that the torsional stress by the present method was approximately estimated by one dimensional theory in relation to dimensions of the dropped bar and the circular bar, material constants of them and the length of the cross pin. In addition, on the basis of the above results an impact torsional testing device of Hopkinson bar type was designed and some experiments were carried out with thin tubular specimens of a low carbon steel (SS41). Torsional stress-strain relations of the material under high strain rates (about 10²/s) were compared with compressive ones. As a result, it was shown that Mises' yield condition was valid under high strain rates as well as low strain rates.

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We considered an elastic contact problem of a half-space indented by a truncated conical stamp, and obtained its rigorous solution. We showed the relation among the resultant load, the indented depth and the configuration of the stamp, and the distributions of the surface displacements and the contact pressures. The surface normal displacement is always larger than the result for a cylindrical stamp, and the difference becomes larger as the slope of the side plane of the stamp, k, tends to be small. The contact pressure has a logarithmic singularity at the corner (r=a) and becomes zero at the contact boundary (r=b). The pressure in r<a is smaller than that for a cylindrical stamp.

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By using the incremental finite element method with triangular plane elements, the snap-through action problems due to thermal expansion of the unit arch spring and the complex ones are analyzed. Then, for the purpose of analyzing the action of the bimetallic arch spring as a typical example of these springs, an effective method with beam-column elements is proposed. The latter method is applied in analyses of the thermal snap-through action of the U- and W-type bimetallic springs for thermoswitches. Then by examining several numerical results by the method of experimental designs, some design formulae for the U-type bimetallic spring are obtained.

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This paper deals with the flexural vibration and the buckling of a circular plate with various constraints on its annular circle. Particularly, the constrained conditions are treated by means of the weighted residual methods when they are partially different on the circle. The reaction force on the constrained parts may be considered an apparent external force, and then the inhomogeneous differential equation is solved. A few numerical results are given and the eigenvalue problems are discussed. The known examples are treated easily by means of this method.

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A reservoir-orifice method has been used to extend the steady flow duration of a Ludwieg tube. The unsteady expansion waves generated by the opening of a valve or a diaphragm interact with the orifice plate which separates the reservoir gas from the supply tube gas. The interaction process is investigated, and the conditions when compression, Mach, or expansion waves will be reflected from the orifice are clarified. During the interaction process above mentioned, the flow from the reservoir is necessarily choked at the orifice. Therefore, it would be impossible to reflect only Mach waves throughout the process of the interaction. The reservoir-orifice method is more effective when a quick-opening valve is employed instead of a diaphragm, and the extended flow duration amounts to about 20 to 50 percent of that of the conventional Ludwieg tube.

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In order to predict both the velocity profile and the relationship between friction factor and Reynolds number for pseudo-plastic fluids flow in smooth pipes, and improved mixing-length distribution is proposed in this paper. This distribution is a modification of Van Driest's model for Newtonian fluids flow obtained by referring to the results of the other researcher's studies about Newtonian and pseudo-plastic fluids. It seems that this mixing-length distribution is suitable for estimating and calculating both the velocity profile and the pressure loss for Newtonian and pseudo-plastic fluids flow in circular smooth pipes through the analyzed results as compared with experimental results. A set of design curves of friction factor versus Reynolds number is presented.

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Small first normal stress differences of fluids are measured by a method which utilizes the reaction force of the jet issuing from a capillary tube. The fluids used in the experiment are water and dilute polymer solutions. The data and the following discussion show that the first normal stress difference is not zero even in a steady Poiseuille flow of water and that the first normal stress differences in various dilute polymer solutions are greater than that of water but not so strikingly different from that of water as expected from the dramatic reducing effect of drag in turbulent flow conditions. These experimental data will be fundamentally available for the construction of a constitutive equation or the analysis of more complicated flows.

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The heat transfer of a critical flow in a small-sized nozzle has not been studied in detail, since the flow is too complicated. In this paper, the two-dimensional compressible laminar boundary layer equations in a parallel nozzle with heat transfer are solved numerically. The obtained results reveal that the two-dimensional critical flow patterns are classified by "nozzle characteristic number x_c". The local and mean heat transfer coefficients in the critical nozzles were calculated by defining an adiabatic wall temperature as gas temperature in reference. Especially, it is found that the local heat transfer coefficients rise sharply near the nozzle exit. The mean Nusselt numbers obtained numerically can be plotted on a single curve independent of the non-dimensional wall temperature θ_w, being arranged on the basis of "modified nozzle characteristic Reynolds number X_cdw"; furthermore they can be approximated by incompressible ones, if arranged on the basis of "X_cdws^-1" defined as the state of sonic point in the critical nozzle.

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Numerical and experimental analyses were carried out with respect to the relationships among the change of diffusion and combustion processes, the location of fuel injection port and the distribution profiles of surrounding air flows. With the object of simulating the complex flow field, a calculation was made under the conditions of three inlets using velocity profiles measured at respective inlets. Effective viscosity expressed in a similar formula to Prandtl one and numerical analyzing procedures of effective difference, finite reaction rate and of combustion efficiency were introduced to improve the applicability and the convergence characteristics of the calculation. The calculation results agreed qualitatively with the experimental ones, and it was concluded that the diffusion rate of fuel is significantly influenced by the fuel supplying position and the surrounding air flows.

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In this paper, a mathematical model on nitric oxide formation in diesel engines was proposed, and the propriety of this model was confirmed by comparing the calculated results with experimental ones. In this model, the gas in the cylinder was devided for convenience sake into three parts, namely, fresh air, burnt gas and the burning part where a constant pressure combustion of stoichiometric mixture was assumed. Then the gas in the burning part was assumed to mix and dilute to the condition of mean excess air factor according to a time function f(t, τ, m). The nitric oxide was assumed to be produced during this mixing process. And, Zeldovich's mechanism of chain reaction was used in calculation. As a result of the present calculations, a desirable agreement between calculated and measured values was obtained under various operating conditions.

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The velocities and accelerations of planar multilink mechanisms have been systematically analysed by means of several transformation functions which describe the relative motions of links in the basic open chains and the conditions of combinations of the open chains. Forces caused by loads, inertial forces and frictions have been also systematically analysed by means of two functions which describe the equivalent inertial forces of links and the internal forces of pairs.

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Following the previous paper the authors investigated the effect of surface roughness on scoring in rolling/sliding contact using a two disc machine. Although the lubricating condition in the previous investigation was very severe, i.e. a starved lubricating condition, in this investigation scoring tests were conducted under a mild lubricating condition, i.e. under a flooded lubricating condition. The scoring resistance of carbon steel was also significantly affected by the extent of work-hardening of disc surfaces and the formation of surface films during running-in in the same way as the previous investigation, that is, the scoring resistance of the discs with small roughness showed duality, and on the other hand that of the discs with rough surfaces increased with the surface roughness. Furthermore, it was confirmed that ferrite phase squeezed out on the disc surfaces played an important role in the formation of oxide films, and that the formation of the oxide films was a necessary condition to prevent scoring at the transition temperature of oil.

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Rotatory machines such as turbines and compressors, almost invariably, include several power transmission gears. The relation between the torsional vibration and the gear transmission mechanism supported by the oil-lubricated journal bearings, however, has never been elucidated. The unstable vibration phenomena (different from ordinary phenomena such as oil whirl, oil whip and so forth) were observed in the locked train type reduction gear system of a marine steam turbine while it was subjected to running conditions with no load. The unstable vibration phenomena are assumed to be due to the self-exciting vibration system which is caused by both the oil film characteristics of the journal bearings which support the reduction gears and the torsional vibration system. The results of the calculations using a dynamic model provide a satisfactory explanation of the phenomena. According to the authors' research, the unstable vibration phenomena are strongly influenced by the torsional rigidity of the system.

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A turning (facing) test on glass-fiber-reinforced-plastics was performed with several tool materials, e.g., sintered carbides, cermets and ceramics, and the wear patterns and wear land growth rate were analyzed to clarify the relationship between physical (mechanical) properties and flank wear of cutting tools. The main results are obtained as follows: (1) When cutting speed is increased, the rate of wear on the nose in every tool material starts to increase remarkably at a certain speed, i.e., a critical speed. (2) Thermal conductivity coefficient versus critical speed curve is approximately linear when plotted on log-log coordinates. The higher the thermal conductivity coefficient of tool material, the higher the critical speed becomes. There also seems to exist an influence of the compressive strength and thermal expansion coefficient of tool materials on its performance in high speed cutting of GFRP.

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