The effect of torsional prestrain on tensile and low-cycle fatigue properties of a medium carbon steel was studied. A series of small-sized tensile and fatigue specimens were prepared from large-sized prestrained specimens in order to ensure good homogeneity of the torsional prestrain in the cross-section of the small-sized specimens. Three modes of prestraining were selected in this study; unidirectional, twistback, and single- or cyclic-reversed torsion. Fracture ductility decreased almost linearly with increasing unidirectional prestrain, while the decrease of fracture ductility in the other modes of prestrain was much less than that in the unidirectional one. A transitional decrease in fracture ductility, which has been reported for inhomogeneously prestrained specimens, was not observed in this study. A slight trace of recovery in fracture ductility due to twisting back the unidirectional prestrain to the macroscopically undistorted original state was observed, in contrast with the almost complete recovery for the inhomogeneously prestrained specimens. The low-cycle life of the unidirectionally prestrained specimens was reduced by an amount which would be predictable from the decrease in fracture ductility of those specimens. For other modes of prestrain, however, the influence on fatigue life was undistinguishably small in this study.

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In this paper, the stress distributions and displacements arisng in a shrink-fit cylinder under torsion are analyzed by applying the point-matching method, which is very useful to analyse elastic contact problems. It is assumed that an infinite solid cylinder is shrink on to a finite hollow cylinder and subjected to torsion at Z=∞, while the outer surface of this finite hollow cylinder is free or fixed by a rigid body.The calculations are carried out for the following two cases : (i) The condition of the shrink-fit surface is complete adherence.(ii) The certain portions of the surface adhere, whereas other slide over one another.The numerical results are obtained for models in the various values of the modulus of elasticity in shear.

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As an example of the non-stationary problems of thermoelasticity for shells, a thin cylindrical shell of finite length subjected to an instantaneous plane hot spot at some point is discussed. Regarding the intensity of a hot spot at some point in the initial state as a delta function and applying Fourier transform, the temperature distribution is determined by solving the non-stationary equation of heat conduction for a shell. The associated thermal displacements and stresses due to this temperature distribution are obtained in the form of double Fourier series by employing the differential equation for thermoelasticity of the cylindrical shell introduced by K.Mizoguchi. The numerical calculations are carried out for a cylindrical shell subjected to an instantaneous plane hot spot at its center, and the temperature distribution, the thermal deflection, and the thermal membrane and bending stresses with the lapse of time are shown in the figures.

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The paper is concerned with a transient creep problem of thin plates with stress concentrated parts (notch or hole etc.) subjected to load in their own plane. In analysis of this problem the finite element method is employed. The solutions are obtainable for two hardening creep laes : the time hardening law and the strain hardening law. As numerical examples some problems on thin plates with a hole or a notch are treated, and the difference between the calculating results from two hardening laws is discussed. The results of the prediction method agree well with experimentally determined values for aluminum plates with circular notches at room temperature.

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Studies on the flow birefringence of polymer solutions and polymer melts in the shear fields are expected to afford useful means for the rheological analysis of a viscoelastic flow.Experiments with Furukawa Polybutene HV 300 and aqueous solution of carboxymethyl cellulose were carried out with concentric cylinder type measuring device to clarify the interrelations between the shear rate γ and the shear stress τ dependences of the fringe order per unit optical path n and the extinction angle λ as weel as the temperature and the concentration dependences of these relations.The shear rate-optical relation obtained was approximated within a confined shear rate range by the following expression. n=C(γ)γ=C_mγ^m where both C_m and m are constants and C(γ) is called shear rate-optical coefficient. The time-temperature and the time-concentration reduction laws held well with n vs. C(γ) relation. Furthermore, the stress-optical relation was approximated by the following formula. n=2C_στ/sin 2X where C_σ is the stress-optical coefficient.

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The impact damper is a device for reducing the vibration amplitude of a mechanical system by the collisions between the damper mass within the container which is rigidly attached to the vibrating system and the container ends.In this paper, the damping effects of the impact damper are discussed for the mass spring system whose spring has nonlinear restoring characteristics. The nonlinear vibration system is approximated by a piecewise linear system. And the fundamental impact vibration when the damper mass collides with the container twice per cycle at equal time interval is treated theoretically, because this type of vibration is considered the most effective in reducing the vibration amplitude of the system.From the results of analysis and numerical calculation, it becomes clear that the domains where the stable periodic motions exist are comparatively large for a soft spring system and in these domains the damper can be considerably effective in reducing the vibration.

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In this paper, the pressure response to the linear change of a flow rate in oil pipelines is treated. The theoretical expressions representing the shape of the pressure response to it have been derived, and the influences of the parameters in the pipeline-systems on the pressure response have been elucidated.The theoretical expressions for the pressure response including nondimensilnal parameters have been indicated as a sum of series, and experiments have been performed by changing the inner diameter of pipeline, coefficient of kinematic viscosity of oil and linearly changing time of the flow rate, respectively. The theoretical expressions and the experimental results agreed with each other, and the results were examined closely. The expressions representing the maximum pressure and the damping properties of the shape of the pressure response have been derived approximately.

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When a layer of fluid heated from below is divided by a horizontal porous wall, the onset of thermal instability is suppressed. The present paper deals with this phenomenon.Visual observations suggest two possible types of convection, one of which is local convection bounded on the top (or bottom) by the permeable wall, and the other is convection passing through the wall. On the basis of these flow patterns, an analysis gives two kinds of critical Rayleigh numbers, the smaller of which is considered to produce convection of the corresponding pattern. Here suppression of convection is caused by an increase in the work done by viscous forces or damping forces. This analysis can approximately explain the experimental values of the critical Rayleigh number. A similar analysis is also made for a porous layer in which there exists a porous wall of smaller permeability.

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In this report, the following analyses, numerical calculations and experimental results are reported, concerning a one-dimensional transient heat conduction problem with melting or freezing.(1) For a substance, the thermal diffusicity of which in solid state is sufficiently larger than that in liquid state, simple approximate equations of the temperature gradient in solid and the temperature distribution in liquid are proposed when the cooling-surface temperature varies slowly and arbitrarily.(2) Using the above equations, an approximate solution for the position of the solid front is proposed as a simple explicit equation.(3) The applicable range of the above equation is discussed through both analysis and numerical calculations, and the limit of application is shown using a non-dimensional parameter.(4) Expermental results for distilled water agree with the above approximate equation within an error of 10% in cases of various cooling-surface temperature changes.

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The growth and collapse data as well as the slip data of vapor bubbles were obtained under surface boiling conditions with water flowing in an annular channel with the velocity ranging from 0.1 to 5 meters per second, and with the subcooling ranging from 20 to 80°C under the atmospheric pressure. With the aid of the existing correlations and related informations, several discussions were made on the temperature profile in the boundary layer and on the bubble characteristics such as the bubble lifetime, the maxium diameter, the time of the maximum diameter and the average velocity in the radial motion during the growth and the collapse stages.

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Because of the complexity of the chemical reactions involved, any current theory of premixed laminar flame cannot absolutely predict the burning velocity. In the present study, based on the analogy between the reactions in the combustion wave and those in the ignition process at a homogeneous mixture, a tentative theoretical model has been established to permit the prediction of the burning velocity from the ignition-delay data. Essentially, this model takes the following matters into consideration; the one is the history of temperature to which a portion of the mixture is submitted during the preheating zone, and the other the broadening of the ignition point caused by the diffusion of chemical species. Applied to methane-air mixture, comparisons of the predicted burning velocities with the measured ones under various conditions have shown a fairly good agreement, suggesting that the proposed model is essentially correct.

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The high-speed photography was used to make clear the influences of lean pre-mixture on the combustion in the cylinder. In this attempt, a 2-hole nozzle was used for main injection, main sprays were deflected in two directions at an angle of 50°. The pre-mixture was intentionally concentrated in one of the two main sprays, so that two different combustion processes with and without the pre-mixture could be compared under the same condition.The results obtained are summarized as folloes : (1) Under the existence of the pre-mixture, ignition nuclei can break out all over the main spray core and even outside of it. The area of breaking out of them is so widened that the flames can rapidly spread over the chamber, and the flaming duration can be reduced.(2) For the favourable results shown in (1), n-paraffins and methyl alcohol are most effective as the auxiliary fuel. Acetone and cyclohexane are not effective at the compression ration of 12. Increasing the ratio to 18, these fuels have the same effectiveness as n-paraffins. In general, it defeats its own purpose to use the aromatics having simple side chains as the auxiliary fuel. Aromatics seem to ignite later than the main fuel.

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Gear rating is decided by tooth strength, surface durability and scoring resistance of gear pair. In Japan, in order to prevent gear-tooth breakage induced by end tooth bearing, gears are often crowned heavily.The stress calculation method for this heavily crowned gear is already proposed by one of the authors, but this calculation method is very troublesome. So, it is desirable that a simple and easy stress calculation method for crowned gear be established.For this reason, the authors proposed a simple and easy calculation method for maximum longitudinal tooth stress of crowned gear using the infinite length cantilever plate theory applied with moment-image method introduced Wellauer, E. J. and Seireg, A.. This simple and easy calculation method is a method by which the maximum gear-tooth stress is obtained as the stress of uniformly loaded spur gear divided by the crowning factor. The crowned gear tooth stress is estimated for the gear-tooth load distribution which is obtained by solving the contact problem about two elastic ellipsoids substituted for meshing gear-tooth.The authors demonstrated by experiments that this crowned gear-teeth stress calculation method is quite proper. Moreover, they proposed the stress calculation method for a special state of end tooth bearing of crowned gear, and proved the practicability of this method by experiments.

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Previous studies of authors on the force-fitted gear have been done for gears having no bosses on their sides and comparatively small size gears.But the force-fitted gears mestly used in various types of macines have bosses on their sides and are of large size.In this paper, the stress caused by force-fitting at the root fillet of gear teeth having bosses on their sides and of large size gears was chosen as the subject of the present study.Moreover bending fatigue strength and stress at the root fillet of these test gears are examined.The following results are obtained.(1) Bending fatigue strength of gears having bosses on their sides is lower than that of gears having no bosses on their sides, and the differences between them are mostly caused by stress concentration at corner of step in gear rim.(2) Calculated results by theoretical and practical formulas introduced for small size gears agree fairly well with the experimental ones of large size gears.

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The principal problem of this paper is to introduce theoretical and practical formulas for the stress at the root fillet of the force-fitted gear tooth in case when gear rim and boss are made of different materials.For experiments five combinations of the gear rim ano bosee made of different materials from each other were chosen, and the stress at the root fillet of tooth caused by force-fitting was measured.Moreover, the bending fatigue strength was examined.The following conclusions are obtained.(1) Theoretical and practical formulas for the stress along the fillet curve of the force-fitted gear can be introduced. So by these practical formulas the stress along fillet curve of the force-fitted gear in case when the rim and boss are made of different materials can be calculated easily.(2) Calculated results by the theoretical formulas agree fairly well with the experimented ones.(3) Coefficients ηψ_Ri, ψ_Bi related to tooth profile, ψ_Ri, ψ_Bi are equal to ψ_Ri, ψ_Bi adopted in case when the rim and boss are made of the same material.

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