Bulletin of JSME
Online ISSN : 1881-1426
Print ISSN : 0021-3764
Volume 11, Issue 48
Displaying 1-24 of 24 articles from this issue
  • Jobu AWATANI, Ryutaro KIMURA
    1968 Volume 11 Issue 48 Pages 939-946
    Published: 1968
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    Properties of friction and wear of Nylon and polyethylene sliding over steel under unlubricated condition were investigated by using a special apparatus ; the amount of wear, the temperature of the sliding surface and the coefficient of friction could be measured at the same time during test. It was found that the temperature of the sliding surface was closely related to properties of wear. The behavior of friction was discussed from adhesion theory, taking account of the temperature dependence of yield pressure and shear strength. The following expression independent of experimental conditions was derived T0+kμpV=Ts for the usable limit, where Ts is the characteristic temperature of material, 120°C for high density polyethylene and 190°C for Nylon-6 and k is a constant depending on experimental conditions. γ-ray irradiation to polyethylene makes Ts high and improves its wear properties, but the irradiation was not so effective for Nylon.
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  • Hironobu NISITANI
    1968 Volume 11 Issue 48 Pages 947-957
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    The effects of size on the fatigue limits and the branch points of electropolished notched specimens were investigated. To clarify the effect of work hardened layers due to machining, the specimens having work hardened layers were also investigated. The main results obtained are as follows. 1) The necessary condition of non-propagating cracks is to take the root radius of a notch under a critical value ρ0 which is a material constant. ρ0 is about 0.5 mm for the 0.23% carbon steel. 2) The repeated maximum stress at the root of a notch at the fatigue limit based on crack initiation is determined only by the stress gradient x=(1/σ) (dσ/dx) at the root of the notch. 3) The size effect of the fatigue limits based on fracture in the range of existing of nonpropagating cracks is explained by the fact that the fatigue limits are determined from the stress concentration factor at the branch point α|ρ0.
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  • Tomokazu MATAKE
    1968 Volume 11 Issue 48 Pages 958-962
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    Following the previous paper (under reversed bending and torsion), fatigue damage of 7 : 3 brass specimens under combined stress is researched by 'annealing-electropolishing method'. Standard damage life, N0, is decided under two stress levels respectively. According to the results, fatigue damage concentrates on the surface of the specimen. N0 becomes shorter rapidly, as σn becomes greater, which is normal stress on the plane of maximum shearing stress. If the ratio of number of stress repetitions to N0 is constant, then the depth of fatigue damage layer is constant also under various stress states. Knowing N0 under reversed torsion, the depth of fatigue damage is decided using an emprical formula, under various stress states.
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  • Yoshihiko HAGIWARA, Kozo HATSUNO, Itsuro AOKI, Hiroshi NAKAMURA, Takes ...
    1968 Volume 11 Issue 48 Pages 963-971
    Published: 1968
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    To clarify the behavior of fatigue strength under service load from the view point of the crack propagation, fatigue tests under successively varying load were performed. In this paper, a prediction method for the crack propagation curve is proposed by applying the superposition law to the crack propagation of the annealed carbon steel specimens and the induction hardened carbon steel specimens, both of which are loaded under sinusoidally varying amplitude. Experimental results show that the Minor's law is applicable to the crack initiation for three materials : 0.17% and 0.36% carbon annealed and 0.17% carbon induction hardened steels. On the other hand, the superposition law is applicable to the induction hardened specimens, but is not applicable to the annealed ones and the results are situated in the dangerous side. Either, the effect of the period of varying load is not recognized in the present three materials.
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  • Rozo FURUHASHI, Masaharu KATAOKA
    1968 Volume 11 Issue 48 Pages 972-982
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    If the elastic coefficients are not constant throughout the whole body, such materials are called inhomogeneous. In this paper, using the concept of the parametrix of the fundamental equations in elasticity, the classical main results in the theory of elastic potentials developed by Fredholm, Weyl, Kupradze and many others have been extended to the case of inhomogeneous materials. Here, by the parametrix of the three dimensional elasticity, we mean the 3×3 square matrix constructed by the nine functions [numerical formula] where, λ and μ are Lame's coefficients, x and y are the points in the elastic body, and δsk is Kronecker's delta. Finally in this paper, the reduction of the fundamental boundary value problems in elasticity to Fredholm systems of singular integral equations is considered.
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  • Toshikazu SHIBUYA, Ichiro NAKAHARA
    1968 Volume 11 Issue 48 Pages 983-992
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    The problem of the semi-infinite body subjected step-wise to a concentrated impact load on the surface is treated by using the dynamical theory of elasticity. By using integral transformation, the results are obtained in forms of dual integrals which involve Laplace inverse-transforms and infinite integrals. The infinite integrals are evaluated by introducing a new variable. Laplace inverse-transforms which are separated from the static results are integrated numerically along the Bromwich integral path. As the result, the variations with time of the displacements and stresses are presented. The displacements and stresses begin to fluctuate suddenly upon arrival of a dilatational wave. In the neighbourhood of the symmetric axis, their absolute values increase till the arrival of a distortional wave. After this arrival, they decrease discontinuously and tend gradually to static results with an increasing time. On the symmetric axis, the radial stress is always compression and becomes maximum just before the arrival of the distortional wave. The circumferential stress is tension except for a short time just after the arrival of the dilatational wave, and becomes also maximum just before the arrival of the distortional wave. The magnitude of the maximum radial stress is about 3 times as large as the static one. The ratio of this stress to the static one in this case is considerably greater than the corresponding ratio in the plane stress state.
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  • Shinichi SUZUKI
    1968 Volume 11 Issue 48 Pages 993-999
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    It has become evident through the author's research that dynamic load factors are much influenced by solid viscosities for the case of a beam and rod subjected to transverse or longitudinal impulsive loads. This paper, treats the case of the ring subjected to uniformly distributed impulsive loads along the inner and outer edges. Loads are assumed to be damped exponentially. Three-element model is used and solid viscosities are represented by two parameters K and η. Approximate calculations are carried out on the assumption that Poisson's ratio is independent of time. The effects of solid viscosities on dynamic load factors of direct stresses in the circumferential direction at the inner edge are investigated. The analysis implies that, as the values of solid viscosities increase, dynamic load factors decrease remarkably in comparison with those for the case of a beam and rod.
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  • Masao SHIBAHARA, Juhachi ODA
    1968 Volume 11 Issue 48 Pages 1000-1014
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    In this paper, the authors consider three-dimensional elastic problems on a circular hollow cylinder under the axially symmetrical deformations. The problems on the cylinder are classified into twelve fundamental cases according to boundary conditions. The general solution to various problems was obtained by expanding each elementary formula to the condition in a form of a Fourier and Bessel series and by superposing the stress systems. As numerical examples, the stress distributions and deformations of a finite hollow cylinder subjected to uniform band pressure were calculated by the digital computer of Kanazawa University (NEAC-2230). This pressure is distributed circularly over the end-surface and over the middle zone of the inner or outer-surface.
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  • Koki MIZOGUCHI, Kaoru SHIRAKAWA, Shigeru HAYASHI
    1968 Volume 11 Issue 48 Pages 1015-1026
    Published: 1968
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    In the present paper, a pressure vessel with an elliptical cross section under uniform internal pressure is considered and the deformations and the stresses produced in it are discussed. As an eliptical cross section, it is conventional, in practice, to use a quasi-one connected by two circular-arcs. To obtain its exact solution the differential equation introduced by Dr. K. Mizoguchi is used and the analytical results are confirmed by the experimental ones obtained by H. Yamanaka and others. The results show that the deformations and the stresses in the vessel have very complicated features according to the forms of cross section and the lengths of shells. As pointed out by one of the authors in the previous paper, it is seen that it is not appropriate to use the energy method and the other approximate ones.
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  • Kiich SATO
    1968 Volume 11 Issue 48 Pages 1027-1036
    Published: 1968
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    In this paper, an approximate solution is given by the use of Galerkin's procedure for the large amplitude free vibration of a beam with immovable clamped ends, subjected to an initial axial load. The results of the vibrations of a beam with one end clamped and other end simply supported are known from those of the vibrations of the antisymmetric modes of a clamped beam. Numerical calculations are carried out for cases of the fundamental vibration of both beams. Finally, a comparison of the increasing rate of the fundamental frequency with the amplitude is made among the beams having different end conditions : both ends clamped, one end clamped and other end simply supported, and both ends simply supported.
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  • Yoshikazu SAWARAGI, Sachio TSUKAMOTO
    1968 Volume 11 Issue 48 Pages 1037-1046
    Published: 1968
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    In this paper, an analytical method of finding the suboptimal controller for a plant consisting of n-th order servosystem with the control signal θ (t) constrained by the condition that |θ (t)|=1 and a stationary Gaussian white noise is presented. The performance criterion considered here is the mathematical expectation of the integrated value of the mean-squared error. By using the dynamic programming method, the problem of this synthesis is reducible to the problem of solving a parabolic partial differential equation for the criterion function. Since, as a rule, it is very difficult actually to carry out the calculations, we use an approximate asymptotic method for the solution of such equations. That is, we asume that solution is expanded to the power series with respect to the dispersion of disturbance, at each approximation, it is determined in such manner as satisfies the necesary condition for optimality.
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  • Haruyuki SUZUKI, Keishi NAKAO
    1968 Volume 11 Issue 48 Pages 1047-1055
    Published: 1968
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    This article describes the probable inaccuracy of thermodynamic method for measuring the efficiency of water turbine. More than twenty water turbines have been tested by this method in Japan already. The writers investigate each error which would happen in all measuring operations, and present the value of probable inaccuracy for the effective head of turbine tested. From the result, the thermodynamic method is thought to be one of the excellant methods for measuring the efficiency of water turbine.
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  • Taijiro KASAI, Sigenori MATSUNAGA, Yukio KUNIKIYO, Haruo ISIBASI
    1968 Volume 11 Issue 48 Pages 1056-1067
    Published: 1968
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    The optimum diameter of axial-flow pumps has been theoretically studied taking the suction performance into consideration. Two high-head axial-flow pumps, composed of two tandem impellers, were tested to study their characteristic performances and suction performances. The main results of the study are as follows. The optimum flow coefficient decreases with the cavitation coefficient of the blade section. The pump, which demonstrates better suction performance and efficiency, consists of a lightly loaded 1st stage impeller with high stagger angle and a heavily loaded 2nd stage impeller of somewhat larger flow coefficient.
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  • Kohji KASAI
    1968 Volume 11 Issue 48 Pages 1068-1083
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    A conical type hydraulic poppet valve with an elastic support (e.g. a helical spring) builds up a complex vibration system with the inlet and outlet piping, and often induces a violent vibration making noise and leading the whole system into unstable conditions. In this report, the author derives the characteristic equation of the whole system including a poppet valve and inlet and outlet pipings. Some theoretical considerations are developed neglecting the outlet piping. The effect of the nonlinearity of the system is also discussed. Some experiments were conducted without outlet piping and varying the length of the inlet piping, spring constant, inlet pressure and other parameters. The experimental results agree fairly well with the theory. The conditions determining the disturbance frequency range in which instability occurs are obtained as a function of length of inlet piping, spring constant, inlet pressure, valve lift, valve shape and Reynolds number.
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  • Takeshi KUSUI
    1968 Volume 11 Issue 48 Pages 1084-1090
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    Concerning the research on the optimum nozzle dimension for hydraulic coal mining and other hydraulic processes, an experiment on the core-length L of turbulent water jet has been caried out on 45 nozzles of various configurations. Increasing the jet velocity, L passes certainly three stages : increasing, decreasing, at last saturating. From the consideration of dimensional relation, an empirical formula for the saturated value of L is given by [numerical formula] where ζs is the hydraulic loss coefficient of nozzle at very high Reynolds number, while fLs is the function of m the area coefficient of nozzle. For ζs<0.26, Ls/d does not depend on ζs. The optimum value of m is nearly 0.2, which gives the maximum value of Ls.
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  • Teruaki AKAMATSU
    1968 Volume 11 Issue 48 Pages 1091-1100
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    This paper deals with an unsteady laminar incompressible boundary layer over a semi-infinite plate set in motion impulsively, in order to elucidate an unsteady boundary layer which develops over a flat plate inserted into a shock tube. Expressing the velocity profiles in the boundary layer by polynomials with two unknown parameters (a boundary layer thickness and a form parameter) and dividing the boundary layer into two regions, there are obtained two momentum integrals, which are reduced to simultaneous differential equations. And the solutions making a smooth transition from upstream (Blasius'solution) to downstream (Rayleigh's solution) are obtained.
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  • Toshiyuki MAEDA
    1968 Volume 11 Issue 48 Pages 1101-1114
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    This report presents the results of a basic research into turbulent boundary layers with injection. The research was conducted solely from considerations of fluid dynamics. It is intended to solve technical problems concerned with a sweat cooling system for gas turbine blades. In the first stage, a theoretical formula for velocity profile in a turbulent inner layer without injection was formed from a basic equation of motion by applying to it the Prandtl's mixing length theory. Separately from this, a turbulent outer layer along a flat plate is understood as one which is featured by the phenomenon of intermittency. Then, the intermittency theory has been amplified to substantiate that the phenomenon in the outer layer can be solved by statistic means. In the next stage, the same theory has been utilized to explain the whole region of turbulent boundary layers with injection. In addition, correlations among factors, which symbolize the velocity profile for turbulent boundary layers, have been found from experimental values. Finally it was proved that the theoretical velocity profile and the mean skin friction for turbulent boundary layers can be calculated simply by using correlative and momentum equations.
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  • Yosimiti TANIDA, Takuro OKAZAKI
    1968 Volume 11 Issue 48 Pages 1115-1134
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    This paper presents a theoretical treatment of cascade blades vibrating in arbitrary mode, under any condition of cascade-whether stalled or not-on a unified basis, by means of the semi-actuator disc method.
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  • Yoshiro KATTO
    1968 Volume 11 Issue 48 Pages 1135-1144
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    In order to establish a bridgehead for attacking the complicated phenomenon of the two-phase critical flow, an exact analysis is initially attempted on an idealized model of constant-area adiabatic two-phase flow. On the process of analysis, it is pointed out that there is a dynamical critical-state which is determined in a self-consistent way from the fundamental equations of dynamics concerned with the flow. With this universal principle of critical state, the afore-mentioned model is analyzed exactly, and the variation of entropy at the critical state is also examined. Although the simplicity of the model adopted poses a problem, not only the analytical results thus obtained show a good correspondency with the experimental results, but also it has various distinctive characters which have not been seen in the existing theories. The study is then moved to the examination of the general structures of logic concerned with the dynamics and thermodynamics included in the analysis, and the results are presented in a clear form discussing important items such as the mutual independency between the regulations of dynamics and the second law of thermodynamics ; the relation between the model and actual flow ; and the state of actual critical flow. In conclusion, it may be noted that the basic dynamic concepts connected with the two-phase critical flow have been clarified.
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  • Koichi WATANABE, Hiroyasu OZAWA, Ichimatsu TANISHITA
    1968 Volume 11 Issue 48 Pages 1145-1160
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    A new equation of state for ordinary water substance in the critical region was formulated based upon the International Skeleton Tables (1963). The new equation of state is given in a form of pressure as a function of temperature and specific volume, and is valid in the ranges of temperatures from 350°C to 650°C, of pressures from 165.37 bar to 1000 bar, where the specific volume is less than about 10 cm3/g. The new equation has a comparatively simple functional form which is convenient for the practical computations with electronii computers and fulfils the condition of the thermodynamic consistency at the critical point in itself, and moreover it can cover the above mentioned entire region by a single formula. The specific volume and specific enthalpy computed from the equation agree well with the Skeleton Table values within the tolerances. The new equation was adopted as one of the subformulations of the 1967 IFC Formulation for Industrial Use.
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  • Ichimatsu TANISHITA, Akira NAGASHIMA
    1968 Volume 11 Issue 48 Pages 1161-1168
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    New equation of the saturation pressure for water is formulated and compared with the standard values of the new Skeleton Tables established by the Sixth International Conference on the Properties of Steam (1963). This new equation has a form of the simple fractional expression which can be easily calculated by an electronic computer, and covers the whole range of temperatures between 0°C and 374.15°C with a single equation. This equation has been adopted as a part of the internationally agreed 1967 IFC Formulation for Industrial Use which are the basic equations for the new International Steam Table. Also reported are values of the heat of vaporization for water calculated from the new equation of the saturation pressure.
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  • Shunichi OHIGASHI, Yoshisuke HAMAMOTO, Seiichi TANABE
    1968 Volume 11 Issue 48 Pages 1169-1174
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    A new measuring technique of gas stream velocity, based on the phenomena that the path of electric discharge moves downstream under influence of gas stream, has been developed. A probe, a thin conductive wire grounded by a resistor, is placed at a distance l downstream from electrodes. When the discharge path arrives at the probe, the probe voltage rises rapidly. By means of measuring the time interval τ, elapsing between the beginning of spark and the rising of probe voltage, the stream velocity w can be determined by the formula, w=kl/τ, where k is a constant, independent of distance l, intensity of turbulence, temperature and pressure of flowing gases. The value of k depends only on electrode spacing. Digital measurement of τ can be made easily. This technique can be applied to not only steady but pulsating flow such as suction flow of internal combustion engines.
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  • Fujio NAGAO, Kazuie NISHIWAKI, Sadao KAJIYA
    1968 Volume 11 Issue 48 Pages 1175-1180
    Published: 1968
    Released on J-STAGE: February 15, 2008
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    For a high-speed engine, valve timing is desired to be automatically controlled by engine speed to secure a good performance over a wide range of speeds. For this purpose an attempt was made to advance valve-closing and delay valve-opening automatically according to reduction of engine speed, by means of a hydraulic tappet with a hole for leakage of oil. The valve lift was measured on a motored engine so as to examine the relation between the diameter of the leak hole and valve timing. The result shows that the leak hole on the plunger controls valve-closing time with less effect on valve-opening, while the one on the cylinder wall influences only valve-opening time. Further, the valve motion was numerically solved by an original theory, which gave a fairly good estimation of valve lift. However, at low speed operation with this tappet, valve seating velocity becomes so high that a special cam profile which has low velocity over a range of closing time is desirable.
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  • Fujio NAGAO, Kazuie NISHIWAKI, Kazuhiko OTSUBO, Fuminobu YOKOYAMA, Tet ...
    1968 Volume 11 Issue 48 Pages 1181-1187
    Published: 1968
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    In order to find the optimum angle-area of the exhaust valve of a two-stroke engine as a function of engine speed, performance tests were carried out with a uniflow-scavenged diesel engine at various speeds under large valve-clearance. The test result showed that the minimum point of indicated specific fuel consumption curve shifted towards lower speed with decreasing valve anglearea, i.e. increasing valve clearance. By analyzing the test results it was theoretically ascertained that the improvement in performance at lower engine speed is mainly due to a decrease in blowdown loss and an increase in charging efficiency. An attempt was then made to control the valve angle-area automatically according to engine speed, by means of a hydraulic tappet with a leak hole, presented in the previous paper. The diameter of the leak hole was chosen so as to give appropriate angle-area for better performance at lower speed on the basis of the above discussion. A performance test with the device showed that fuel consumption improved over the lower speed range, especially under heavy load. The fuel consumption vs. engine speed curve approximately forms an envelope of the ones obtained in preceding tests. However, this tappet has a drawback of high valve seating velocity. This problem must be solved for practical use.
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