Rotating beam fatigue tests over the temperature range 20-450°C were made on low carbon steel in annealed and low-temperature-quenched conditions. The relationship σ_w=C_w+k_wd^-1/2 which describes the dependence of the fatigue limit σ_w on the grain diameter d has been proved in this series of experiments to apply up to about 400°C. Both of the two constants C_w and k_w reached the maximum at 350-375°C and the minimum at about 200°C. The existence of the maximum in the values C_w and k_w is found to be caused by a rapid strain ageing. The fatigue strength at 450°C was independent of the grain size. Below 400°C, σ_w is increased by quenching. The increase in σ_w is induced by an increase in C_w, not in k_w, which is little influenced by quenching. The increase in C_w only may be explained as the consequence of precipitation hardening due to quench-ageing developed prior to fatigue stressing .

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The dynamic response of a cylindrical shell with finite length to a concentrated impact load on its arbitrary surface is studied. The response of radial displacement and stresses is made clear through the analysis which is carried out by using the theory considering not only radial but also in-plane inertia forces, and the effect of these inertia forces on the response of them is also examined. The relation between their maximum values and the ratio of length to radius of shell is shown, in addition to the dynamic load factor of the radial displacement.

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The moire topographic method using one grid or two grids is one of the most powerful means for measuring the surface contour of a three dimensional uneven object. But, so far this method has taken no account of the subject of discriminating between the concave and convex parts of an object. In this paper, new equations for the moire topographic method are presented, which contain a new factor for distinguishing between the projection and depression of a body to be measured. Further, in the case of two grids methods, it is shown that the mismatch method or the grid shifting procedure is an effective means for discriminating between the concave and convex parts of an object, and also the grid shifting procedure is very useful for obtaining the correct surface contour in the neighborhoods of the top and bottom of an uneven object.

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This paper studies harmonic wave propagation in an infinite elastic bar of elliptical cross section with stress-free surface by using Mathieu functions and modified Mathieu functions which are the exact solutions of the equation of motion from linear elasticity in an elliptical cylinder coordinate system. We give a procedure leading to the frequency equations for longitudinal, torsional and flexural waves by making use of the orthogonal properties of Mathieu functions. Numerical calculation for each mode is carried out.

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It is said to be difficult even for a bus to secure the directional stability and shorten the braking distance by means of the ideal braking force distribution, since it is affected significantly by the friction coefficient between brake linings and drums. It, however, becomes clear through the theoretical analyses and many experiments that the optimum control of braking force distribution is achieved successfully by using a new device which consists of disc brakes at rear and drum brakes at front. The latter are equipted with specially designed wheel cylinders to mitigate self-energizing action.

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The sensitivity of closed loop poles which are assigned to desired locations by state feedback is shown as a function of redundant parameters of the feedback gain matrix. The pole sensitivity is found to be adjustable even if these poles are fixed. An algorithm for designing the redundant parameters which lower the sensitivity of these poles to variations in the plant parameters is derived. An example is given to verify the effectiveness of this procedure.

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This paper deals experimentally with the mechanism of an impulsive pressure generated by a collapsing bubble. In a water filled shock tube, an expansion wave and a subsequent compression wave are applied to single, twin and triadic bubbles. The growth, collapse and rebound of bubbles situated at various distances from a solid boundary are observed by means of high-speed photography and in-line Fraunhofer holography using a pulsed dye laser. The results indicate that the impulsive pressure is caused by a shock wave radiated at the instant of the rebound of a collapsing bubble, and that the subsequent jet impingement does not produce any detectable effects. The pressure pulse is found to be of the order 10⁴ ∼ 10⁵ atm, and its duration 2 ∼ 3 μsec.

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In this paper, the numerical solutions are presented which describe the pressure-time relationship that occurs at the end of a pneumatic transmission line following large pressure changes through the magnetic valve at its inlet. One dimensional continuity, momentum and energy equations describing the flow in a pneumatic transmission line have been solved numerically using the Runge-Kutta method for the inlet condition based on the flow rate through the valve. When the energy equation is used in them, the agreement between the experimental results and the numerical works is found to be dissatisfactory, because it is difficult to evaluate the wall shear stress and surface heat flux for the unsteady flow. If the flow is assumed to be barotropic, however, the calculated values for the isothermal flow show good agreement with the experimental results.

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Recently pressure and speed of hydraulic equipment tend to grow higher and higher, and therefore, cavitation and aeration in hydraulic fluid flow become a problem of engineering. So it is important to measure the bubble content of the hydraulic fluid quantitatively. For our study we used the light transmission method to measure the void fraction of bubbles in hydraulic fluid instantaneously. So we studied experimentally by using this method and discussed the results by theoretical analysis.

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In the present study the behavior of heat transfer in a rectangular cavity with one isothermal vertical wall heated and the other cooled is investigated. Heat transfer coefficients on the vertical walls are measured for fluids with Prandtl number Pr of 3 to 40, 000 in case of aspect-ratio H/W from 5 to 47.5 and their correlated results are presented for laminar, transition and turbulent regions, respectively. It is shown that the present arrangement (Nu_H-Ra_H) using the height of cavity as a representative length may significantly by useful in the various heat transfer modes accompanied with flow patterns of them.

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The effect of buoyancy force on laminar heat transfer rate downstream of a sudden enlargement of a two-dimensional duct is numerically discussed for a variety of velocity profiles at entrance to the enlarged part. It is clarified that variation of physical properties or of Grashof number with change of wall heat flux has a considerable influence on convective heat transfer as well as flow pattern, and that the Nusselt number in a separated region is closely connected with the velocity profiles at entrance to the enlarged part.

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The radiative and convective heat transfer from a longitudinal rectangular fin array on a plane surface has been analytically investigated by applying the Monte Carlo method. Optimization of the heat transfer performance of the finned plate system has been examined for various combinations of parameters : emissivity, Biot number, radiation number, convection-radiation parameter, fin spacing to fin height ratio, fin height to fin thickness ratio and specular component of reflection.

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Temperature distribution within a rotating cylinder, in which heat is generated locally on the surface at a band heat source, and is removed over a local cooling band on the surface, is calculated by means of the Rayleigh-Ritz Method. Numerical results are graphically illustrated. The method proposed here is more applicable than functional analysis to the problem with some types of complex boundary conditions such as those of local cooling. It is also more applicable than numerical analysis to the problem with moving heat source and moving boundary conditions.

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In this first report in a series of studies to measure the thermal conductivity of fluids at high temperature and high pressure, preliminary studies on the reliability of a transient hot-wire method and measured results of eight liquids are described. Measurements were performed for water, methanol, ethanol, benzene, acetone, glycerin, refrigerants R11 and R113 at atmospheric pressure in the temperature range -90 - +80°C. Empirical correlations were established for each liquid. Comparisons with available data in literatures showed reasonably good agreement for most of liquids.

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Several empirical equations have been proposed of the interfacial friction factor in a gas-liquid tow-phase annular flow, but there exists a significant inconsistency among the results calculated by these correlations. In addition, none of them indicated good agreement with the present experimental values obtained in ripple flow regime. An experiment was made to collect the information on main parameters characterizing air-water interface, such as wave height, wave propagation velocity and wave frequency, possibly interrelated with the interfacial friction factor. Using the results, there of a new relationship between the interfacial friction factor and the parameters was introduced.

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Air swirl speeds were measured in a motoring and firing run of a direct injection diesel engine, and the results were compared with those in steady flow tests. Experimental results show that, during the combustion period, the swirl speed in the firing condition is almost the same as that in motoring. There is a linear correlation between the swirl speed predicted from the results of the steady flow tests and that measured at top dead center in motoring. Therefore, it is recognized that the steady flow test is available to evaluate a swirl producing ability of inlet system of engine. The reduction in swirl speed during the compression period was estimated by considering the friction force acting at the air-solid interfaces.

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This paper reports on a theoretical calculating procedure of the oil film behaviour between the piston ring and the cylinder wall. The analysis assumes: (1) that the sliding surface of the ring may be approximated by a parabola; (2) that the oil film viscosity is constant; and (3) that the trailing end of oil film pressure varies according to the Reynolds boundary condition, namely the pressure profile ends at apposition where the pressure becomes a downstream pressure and also the pressure gradient becomes zero. The paper gives also an example of oil film behaviour between the circular-faced piston ring and the cylinder wall which has been calculated under the conditions corresponding to a small sized 4-stroke cycle kerosene engine.

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Dynamic characteristics of planar mechanisms with clearances are studied with use of Lagrange's equation of motion. In general multi-link planar mechanisms, the equations of relative motion between two links joined by a revolute pair are derived considering the friction at the pair, and the conditions for separation and contact of two pair elements are determined. Such theories are proved to be applicable to the mechanisms with prismatic pairs, and are practically applied to a four-link mechanism which has three revolute pairs with clearances and to a slider-crank mechanism which has revolute pair with clearance. The dynamic behaviors of those couplers and follows are analyzed theoretically and experimentally.

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By means of pairing the guides and rollers of rolamites with each other, a new mechanism with multi-degree of freedom whose inputs and outputs are displacements and/or forces has been derived. The mechanism has been called a compound rolamite, and an analysis of the number of the elements and quantities determining the mechanism, a construction of the fundamental structure and a determination of the necessary band-gener-ated forces for the prescribed output function have been carried out with some examples of its application given.

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In this paper, the workpiece regenerative chatter during cylindrical traverse grinding is theoretically analysed. The depth of cut, which is closely related to the grinding stiffness and the contact stiffness, is assumed to change stepwise in the wheelwork contadt area due to the elastic deformation between the grinding wheel and the workpiece. It is theoretically indicated that the depth of cut of the last step could not be zero. The growth ratio of waves, which are generated on the workpiece surface during successive two revolutions of the workpiece, is derived in order to discuss the stability of grinding process. Theoretical results show that the chatter vibration tends to occur under the grinding conditions such as low traverse speed, high workpiece speed, wide wheel width, and small depth of cut. A few experiments were carried out to discuss the theoretical results. Both results showed qualitatively good agreement.

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In the estimation of scoring limit of gears, it is supposed that the effect of metal-structure and hardness is important. In the present report, the scoring limit was studied by using an Amsler wear testing machine. The materials of test rollers were steels specified under JIS S43C, SCr4 and SCM22H. From experimental results on various metal-structures from ferrite-pearlite structure to martensite structure, it became clear that the scoring limit increases with the hardness and an initial scoring takes place on the surface of steel containing a small quantify of retained austenite.

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(1) The influence of the tightening velocity on the friction coefficient of fastener μ was investigated. (2) The influence on μ of the lubrication state, the surface treatment and the material combination of bolts and nuts was examined from the viewpoints of the central tendency and the dispersion. (3) The screw-thread friction coefficient μ_S and the bearing-surface friction coefficient μ_W were measured separately. Both the mean value and the standard deviation of μ were calculated statistically with the data of μ_S and μ_W, and a comparison between the calculated and the experimental results was made. (4) Some coating materials to reduce the standard deviation of μ, which are called "μ-stabilizers", were tested, and it was found that they are useful for decreasing the variation among subgroups.

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The effects of back tension on the lubricating conditions are investigated on a laboratory rolling mill for three nonferrous sheet metals. Back tension lowers the inlet pressure and helps the lubricant to enter the roll bite, thus brightness of the rolled surface and in most cases the coefficient of friction are decreased by increasing back tension. Though the variation in oil quantity dragged into the roll bite may be estimated by the proposed parameter t_d=η(U₀+U₁)/[α(2κ₁-p₁)], the coefficient of friction depends on not only t_d but also reduction and material rolled . Some of the reasons are also suggested.

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