Bulletin of JSME
Online ISSN : 1881-1426
Print ISSN : 0021-3764
Volume 23, Issue 179
Displaying 1-21 of 21 articles from this issue
  • Tomokazu MATAKE, Yasufumi IMAI
    1980 Volume 23 Issue 179 Pages 623-629
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    From the fatigue test of notched specimens of isotropic 70:30- brass, under bending, torsion, and combined stress state of them, a simple criterion for the slip-band crack initiation has been obtained. In spite of the complexity of the triaxial stress state below the notch root, only two stress components, the maximum shearing stress τmax and the normal stress σn acting on a particular slip plane, are responsible for initiating slip-band cracks. Using the averaged stress values over the half-grain-size depth below the notch root, linear sum of them, τmax + a·σn, acts just as the torsional stress in unnotched specimens. At the fatigue limit, therefore, the value for any combined stress state coincides with the torsional one. This relation is more general than the one which has been obtained before for unnotched specimens because of including the case for the unnotched as an extremely shallow notch.
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  • Takashi KAWAKAMI, Ichiro NAKAHARA, Eiichiro TSUCHIDA, Hiroyuki MATSUMO ...
    1980 Volume 23 Issue 179 Pages 630-636
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    This paper contains an analysis of the distribution of stresses in a circular cylinder having an eccentrically located spherical cavity under axial uniform tension. The method of approach is based upon the harmonic stress functions which are the general solutions of the equations of equilibrium in terms of displacements proposed by Dougall and Neuber. Owing to the linearity of elasticity, a solution can be obtained by superposing two solutions; one is expressed in terms of the cylindrical harmonics whose origin lies on the center axis of the cylinder, and the other is in terms of the spherical harmonics whose origin is at the center of the cavity. In order to superpose these solutions, we get the transformation formulae between these harmonics by altering Graf's formula. Then, making use of these relations, we can satisfy the boundary conditions on both surfaces of the cylinder and the cavity. Numerical results are given for eccentric distance c=0.25 with the ratio of the cavity radius to the cylinder radius varying 0.1∼0.5, and the stress distributions around the cavity are shown graphically.
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  • Toshikazu SHIBUYA, Takashi KOIZUMI, Kazuyoshi SUZUKI
    1980 Volume 23 Issue 179 Pages 637-643
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    We considered the problems of determining the stress intensity factors of two or infinite parallel external circular cracks in a hollow cylinder under torsion. We reduce these problems to solving an infinite system of simultaneous equations. Numerical results obtained for the stress intensity factor are worked out for various values of the distance between the cracks.
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  • Toshiaki MURAKAMI, Tetsu YANUKI, Masatsika NAKANO, Mitsuru ARII
    1980 Volume 23 Issue 179 Pages 644-649
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    In this paper the point-matching method is used to calculate the asymmetric contact pressure and stress distribution of a cylindrical shell induced by shrinking an asymmetric disk (which has a circular disk, sectors and ribs). The classical theory of thin shells developed by Flugge is used to calculate the asymmetric displacement of the shell and two-dimensional elasticity theory is used to calculate that of the disk. In calculating the radial displacements of the disk, sectors and ribs are in contact with the circular disk and the stress functions for the sectors and circular disk are used. The calculated distribution of the radial displacements of the cylindrical shell is in good agreement with the experimental data. The axisymmetric stress resultant Nφ, moment resultant Ms and asymmetric moment resultants Mφ, M are dominant stresses in the shell.
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  • Masataka SHIRAKASHI, Yukio TOMITA
    1980 Volume 23 Issue 179 Pages 650-655
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    To investigate the diffusion phenomena in the intermittent region near the turbulent interface, theoretical and experimental studies are made on the material diffusion in the mixing region of a non-turbulent flow and a turbulent flow behind a grid with equal velocity. A new expression for the coefficient of eddy diffusion which takes into account the decay of turbulence is proposed. The calculated curves using this expression agree well with the experimental results. It is pointed out that a critical frequency plays a significant role in the phenomena near the turbulent interface and that large eddies whose frequency is lower than this critical value contribute only to the bulk convection. Standing on this fact, it is shown that the mean concentration distribution calculated by the method proposed in our preceding paper coincides with the measured results.
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  • Yoshinori KITA, Yukio ADACHI, Koji HIROSE
    1980 Volume 23 Issue 179 Pages 656-664
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    A fluctuating eddy viscosity model for Reynolds stress is proposed. The validity of this model is verified for all frequencies tested through comparisons between the calculations and measurements. The analysis yields three properly-modified Strouhal numbers: the first of them is adequate to illustrate similarly the velocity distributions in turbulent region over a wide range of frequencies and the time-mean Reynolds numbers, the second is adequate in the vicinity of wall, the last is for the instantaneous friction factor. The following results are obtained: at low frequencies the amplitude of the wall shear stress is proportional to the amplitude of the velocity. At high frequencies it is proportional to both the velocity amplitude and the square root of the frequency. The predicted magnitude of the instantaneous friction factor exceeds that of steady state during accelerating flow and it is smaller than that during decelerating flow.
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  • Kouji KIKUYAMA, Mitsukiyo MURAKAMI, Hiroaki MATSUMOTO
    1980 Volume 23 Issue 179 Pages 665-671
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    The flow patterns and pressure recoveries in rotating, conical diffusers were investigated experimentally. The conical diffusers have straight walls and opening angles of 7°, 10°, 15°, respectively. Even in a diffuser having no separated zone in a stationary state such as in the case of diffusers with an opening angle equal to or less than 10°, separations occur on the lower pressure wall when the diffusers are rotated at a speed exceeding a certain limit. Velocity profiles and pressure distributions as well as the flow separation in diffuser sections are governed by a parameter defined by the ratio of a rotational Reynolds number to a flow Reynolds number. As the rotation rate increases, the point of separation approaches the inlet section of the diffuser and wakes formed by this separation grow in size, resulting in a poor pressure recovery in the diffuser. At the same rate of rotation, the pressure recovery in the diffuser with an opening angle 10° was the best of the diffusers tested.
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  • Jun MASUZAWA, Takahiko TANAHASHI, Tsuneyo ANDO
    1980 Volume 23 Issue 179 Pages 672-678
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    The entrance region for laminar flow in porous pipes with small injection or suction is theoretically analyzed. In this paper, a modified momentum integral method in the first report is applied to the entrance flow with a uniform inlet profile, and the following conclusions are obtained. (1) The velocity and pressure distributions, and the wall frictions in porous pipes are obtained by this modified method, and the results are in good agreement with those of Hornbeck's numerical analysis. (2) When the suction velocity is large, the pressure rises and the wall friction is small in the downstream region. (3) The larger the injection velocity is, the shorter the entrance region in porous pipes is. (4) When this method is applied to the entrance flow in rigid pipes, the results are also in very good agreement with the results obtained by Nikuradse et al.
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  • Morimatsu OHKI
    1980 Volume 23 Issue 179 Pages 679-686
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    Unsteady flow of a viscous, incompressible fluid in a semi-infinte circular tube with a porous, elastic wall whose length varies with time, but whose cross-section does not vary, is studied considering the effects of suction or injection on the wall. Laminar, similar solutions with respect to space and time are obtained. Velocities, pressure, drag, power and work of fluid are analyzed. There are the critical conditions of suction and injection on the wall in accordance with the conditions of motion of the wall either contracting or expanding in an axial direction. The conditions of suction and injection are divided into two parts, giving a classification of the situations of the induced flow fields.
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  • Hiroshi NAGATA, Tatsuya MATSUI, Haruo YASUDA
    1980 Volume 23 Issue 179 Pages 687-695
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    The flow around a circular cylinder started impulsively in water at rest was studied by the hydrogen bubble technique for the Reynolds number of 1200 based on the diameter of the cylinder. Taking into account the velocity defect behind the bubble generating wire, a method of calibration for quantitative determination of the flow velocity was established. In order to see the influence of the growth of separation vortices formed behind the cylinder on the potential flow field, the velocity field near the cylinder surface and the vorticity flux shedding from the boundary layer through the separation points were measured in relation to the time elapsed. The potential flow around the cylinder was found to change markedly with the time in which the growth of vortices in the wake was promoted.
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  • Hiroshi NAGATA, Tatsuya MATSUI, Masahiro ICHIKAWA
    1980 Volume 23 Issue 179 Pages 696-704
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    A procedure for obtaining true velocities which were estimated from the locations of time-lines visualized by hydrogen bubble technique was developed by taking into account the velocity defect behind a bubble generating wire. By using this technique, the velocity profiles in unsteady boundary layer on the circular cylinder which was started impulsively in still water were obtained at the Reynolds number of 1200 based on the cylinder diameter. changes in the displacement thicknesses and shape factors were determined in course of time and were discussed in comparison with the results by the existing theories. Velocity profiles of the boundary layer before and after the occurrence of a reversed flow were also measured. These velocity profiles were in fairly good agreement with Pohlhausen's profile, even at the location where a reversed flow appears. And they seem to change gradually before and after the occurrence of a reversed flow, unlike the velocity profiles at separation points in ordinary steady flows.
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  • Eiji HASEGAWA, Nobuyuki TANIYAMA
    1980 Volume 23 Issue 179 Pages 705-710
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    The stability problem of a liquid layer flowing down an inclined plane wall is studied theoretically, taking into account the time dependent wind stress on its free surface. The Floquet theory is applied to a differential system with periodic coefficients of this problem. This system is solved by the long wave approximation. The critical Reynolds number for this flow depends on the square of the amplitude of the wind fluctuation. The frequency of the wind fluctuation has the greatest influence on the instability of the liquid layer when the thickness of the liquid layer is of the same order as the thickness of the Stokes layer due to the oscillating motion. In case of low frequency the flow is destabilized by the wind fluctuation, but in a range of high frequencies the flow can be stabilized slightly.
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  • Chuji MIZUNO, Masayoshi KOBIYAMA, Yutaka YOSHIDA, Kiyoshi ENOKI
    1980 Volume 23 Issue 179 Pages 711-716
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    The thermodynamic optimum point of the suction air cooling gas turbine cycle with a vapor compression refrigerator is investigated. The maximum thermal efficiency and the maximum specific power increase monotonously with a rise of the temperature ratio by the suction air cooling, but the rate of increase of the thermal efficiency has a tendency to give the optimum value and that of the specific power has a tendency to decrease monotonously, compared with the conventional cycle. The effect of the reversed cycle (refrigerator) on the normal cycle (heat engine) is investigated. The effect on the thermal efficiency is larger than that on the specific power in the region of high temperature ratios.
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  • Chuji MIZUNO, Masayoshi KOBIYAMA, Yutaka YOSHIDA, Kiyoshi ENOKI
    1980 Volume 23 Issue 179 Pages 717-723
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    The authors analyze the performance at the partial load of the suction air cooling gas turbine cycle with a vapor compression refrigerator. The partial load is adjusted by changing the inlet gas temperature of the turbine, keeping the number of revolutions of the turbine and the flow rate of the inlet air of the air compressor in a constant state. The analytic results show that the gains in thermal efficiency and specific power at the partial load are in the same degree as at the design point, and that this cycle can suppress a variation of the performance caused by a change in atmospheric temperature at the partial load as well as at the design point, compared with conventional cycle.
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  • Ken KISHIMOTO
    1980 Volume 23 Issue 179 Pages 724-731
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    One of the most important characteristics of combustion processes is a flame temperature. However, the local temperature of an electrically augmented flame is too high to measure by the conventional methods. A new technique has been developed using a water cooled pneumatic probe. The results by this method show good agreement with the input energy with 3% error. In this paper, this technique is compared with other methods and some factors affecting its operation are discussed.
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  • Yoshitaro HIRANO, Katsutoshi OKAZAKI
    1980 Volume 23 Issue 179 Pages 732-740
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    The present paper deals with vibration problems of cracked rectangular plates. The two opposite edges perpendicular to the line of the crack are assumed to be simply supported in these plates. Therefore, the Levy-Nadai's form of solution is used. Fulfilment of mixed boundary conditions on the line of the crack are formulated by means of the weighted residual methods. Numerical calculations are carried out for three examples; In the first example two opposite edges parallel to the crack are assumed to be simply supported, in the second, free, and in the last example clamped. Results of calculation are compared with the works of other investigators.
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  • Takafumi FUJITA, Shinobu HATTORI
    1980 Volume 23 Issue 179 Pages 741-748
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    This paper deals with the response of a nonlinear system with collision subjected to a stationary random excitation. The system consists of an oscillator and reflectors at both sides. Various stochastic properties of the response are determined analytically, including the joint probability density function and the root-mean-square values for the displacement and the velocity of the oscillator, the average number of collisions per unit time, and the probability density functions, the mean values and the standard deviations of the impact velocity, the impulse and the impact acceleration. Experiments are also carried out to examine the analytical results, and good agreement between the analytical and the experimental results is obtained. Numerical results are presented to show effects of the clearance gap between the oscillator and each of the reflectors on the stochastic properties of the response. The width of the gap for snubbers is evaluated, employing the average number of collisions whose impact velocities are beyond a certain level.
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  • Katsumasa MATSUURA
    1980 Volume 23 Issue 179 Pages 749-758
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    A numerical and physical study is made concerning the non-stationary transitions of motion of a rotor with the condition that it can easily pass through a resonance. As a result of this study, theoretical design criteria for a rotor with a usable limit are introduced, and these criteria are compared with the results of experiments in which an actual rotor is used.
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  • Satoru HAYASHI, Takashi MATSUI, Kanehisa IMAI
    1980 Volume 23 Issue 179 Pages 759-765
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    This paper discusses the stability of a system consisting of nozzle-flapper valve and a pipe line and several features of the self-sustained oscillations occurring in the system. Conclusions are as follows: (1) It is shown that the multiple modes of oscillations may simultaneously become unstable in a system with a long pipe line. (2) It is made clear that the most effective nonlinear characteristic for limiting the amplitude of the unstable oscillation is the collision of the flapper with the nozzle tip. (3) A basic equation of the system including the equivalent nonlinear terms for the collision is proposed and approximately analysed to derive the frequency and the amplitude of the self-sustained oscillations. (4) The selective occurrence of a self-sustained oscillation is also investigated for a system having two unstable modes, and it is concluded that either of the two unstable modes selectively develops to a sustained oscillation.
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  • Sanae WADA, Masafumi TSUKIJIHARA
    1980 Volume 23 Issue 179 Pages 766-772
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    In this paper, an elastohydrodynamic squeeze problem between two spherical bodies lubricated with grease is studied. In this analysis, grease is assumed to be a Bingham solid whose plastic viscosity and yield stress depend on the pressure, and the time-dependent elastohydrodynamic equation for a Bingham solid is solved by the same method presented in the author's previous paper. It is discussed how the core formation, which is the inherent property of a Bingham flow, affects the film profile and the load capacity. In the experiment, a spherical body is dropped onto a lubricated optical flat and the film profiles are measured using the interferometric method and photographed by a highs peed cinecamera. It is discussed, using grease and gear oil, how the various lubricants affect the film profile. analytical results and experimental ones are compared.
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  • Sanae WADA, Hiromu HASHIMOTO, Tomoyuki NAKAGAWA
    1980 Volume 23 Issue 179 Pages 773-780
    Published: 1980
    Released on J-STAGE: February 15, 2008
    JOURNAL FREE ACCESS
    This paper presents a study of turbulent lubrication considering thermal effects on lubricant film. By applying a turbulent lubrication equation and an energy equation to finite width journal bearings and analyzing these equations numerically, the bearing performances such as film temperature and pressure are evaluated. Moreover, the dynamic characteristics such as stiffness and damping coefficients of lubricant film and the stability of rotor are also analyzed. The results obtained here show that the thermal effects on the bearing performances and the dynamic characteristics are prominant in the turbulent lubrication.
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