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Tsunenori OKADA, Kaoru AWAZU
1981 Volume 24 Issue 189 Pages
461-467
Published: 1981
Released on J-STAGE: February 15, 2008
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To clarify the effects of corrosive liquid on the behavior of cavitation erosion, erosion damage of carbon steel in salt water has been compared with that in ion-exchanged water in a microscopic view by means of observation of the eroded surface by an SEM, and the following results are obtained. The erosion damage is highly affected by the grain orientation on the test surfaces. That is, on easily corroded grains many corrosion pits are formed originating from the crack propagation. However, on not easily corroded grains, slip bands are dissolved as soon as they are created, and therefore cracks are hardly formed in salt water unlike in ion-exchanged water.
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Kazuo HONDA, Tashiyuki TORII
1981 Volume 24 Issue 189 Pages
468-474
Published: 1981
Released on J-STAGE: February 15, 2008
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Quenched clad plates of low carbon steel and middle carbon steel were made as models of the laminated inhomogeneous metals such as induction hardened steels and carburized hardened steels. By using these clad plates, effects of the initial residual stress and the laminated inhomogeneity on the fatigue fracture were discussed. Main results obtained are as follows: The initial residual stress resulted in causing only the mean strain for the hysteresis loop, so that the fatigue lives of the clad plates were little influenced of the hardened layer-elasticity and softened layer-plasticity. Considering the slip deformation in biaxial stress of the low carbon steel layer, the estimated fatigue lives fairly well agreed with the S-N curves except in the vicinity of the fatigue limit of the clad plates.
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Norihiko HASEGAWA, Motohisa HIROSE, Yozo KATO, Yasushi SATO
1981 Volume 24 Issue 189 Pages
475-482
Published: 1981
Released on J-STAGE: February 15, 2008
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The effect of the rapid strain aging during fatigues stressing at 350 ∼400 °C on the fatigue strength of a low carbon steel plate was examined. The fatigue tests were made in plane bending at room temperature, 200°C, 375°C and 450°C. Both of the endurance limits of the sharp notched specimen, that is, the critical stress required for crack initiation and that required for crack propagation reached a maximum at 375°C and a minimum at 200°C. The threshold stress intensity factor range of a precracked specimen also reached a maximum at 375°C. The number of cycles to crack initiation and that to fracture at higher stress than the endurance limit showed the same temperature dependence as described above. The rapid strain aging at the peaking temperature is more effective inhibiting the crack propagation than the crack initiation.
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Norio HASEBE, Minoru UEDA
1981 Volume 24 Issue 189 Pages
483-488
Published: 1981
Released on J-STAGE: February 15, 2008
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A semi-infinite plate with a step and a crack originating from its angular corner is analyzed as a plane elastic problem. Uniform tension is considered as the boundary condition. Stress distributions are analytically calculated for the state before and after the occurrence of a crack. Stress intensity factors which are important in linear fracture mechanics are analytically calculated and are investigated for some angles of the angular corner and various crack lengths. The influence of the step on the stress intensity factors is also investigated. A rational mapping function which maps the semiinfinite region with a step and a crack into a unit circle is formed as a sum of fractional expressions. The rational mapping function and Muskhelishvili's method are used for the analysis. A closed solution which is exact for the shape represented by the rational mapping function is obtained.
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Toshikazu SHIBUYA, Takashi KOIZUMI, Kazuyoshi SUZUKI
1981 Volume 24 Issue 189 Pages
489-494
Published: 1981
Released on J-STAGE: February 15, 2008
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In a solid with many cracks, the stress field is affected by the mutual interference of cracks. The effect of the interference of many cracks comes between those of two and infinite cracks. Therefore, in the present paper, the torsional stress state of a hollow cylinder with two or infinite parallel internal circumferential cracks is considered on the basis of the theory of elasticity. Numerical results are illustrated for the distributions of displacements and shear stresses and for the relations between the stress intensity factors and the crack dimensions. The stress intensity factors in the case of infinite cracks are smaller than those in the case of two cracks. The stress intensity factors in both cases increase with an increasing distance between cracks, and tend to that in the case of one crack.
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Yotaro MATSUO
1981 Volume 24 Issue 189 Pages
495-500
Published: 1981
Released on J-STAGE: February 15, 2008
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In the previous works, including Weibull's, the relative coefficients of the multi-axial probability distribution functions for brittle fracture are proposed on the basis of uni-axial tension. On the contrary, in this paper, it is considered that Weibull's uniaxial distribution function is exactly correct only in case of tri-axial uniform tension. Then, new relative coefficients are proposed, which are constant and independent of the crack shape or condition of crack propagation, and some discussions are made on Weibull's parameters.
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Eiryo SHIRATORI, Kozo IKEGAMI, Tatsuhisa ISHII
1981 Volume 24 Issue 189 Pages
501-506
Published: 1981
Released on J-STAGE: February 15, 2008
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It is difficult to increase the radial strength of a circumferentially fiber-reinforced disc. a new reinforcing method by laminating and filament winding is proposed. The reinforcing effects of laminating or fastening the filament winding on a quasi-isotropic disc are investigated theoretically and experimentally in order to increase the rotating strength of the composite disc. The following results are obtained : 1] Analysis by the laminated plate theory gives a dangerous estimation of the rotating strength for a thick laminated disc. 2] Fastening the filament winding of carbon fiber outside the quasi-isotropic disc has a large effect of increasing the rotating strength, while the reinforcing effect by axial lamination is small.
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Fusahito YOSHIDA, Izumi OHTA, Eiryo SHIRATORI
1981 Volume 24 Issue 189 Pages
507-513
Published: 1981
Released on J-STAGE: February 15, 2008
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Cyclic creep behaviors of carbon steel are investigated by the true stress controlled low-cycle fatigue tests, stepwise or linearly increasing or decreasing maximum stress with a changing stress ratio. The constitutive equation proposed previously by the authors is found to be applicable to represent the strain accumulations in both increasing and decreasing stress conditions. The shape of the hysteresis loop including the cyclic creep strain increment is also discussed.
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Hideaki KASANO, Hisashi OSHIMA, Hiroyuki MATSUMOTO, Ichiro NAKAHARA
1981 Volume 24 Issue 189 Pages
514-519
Published: 1981
Released on J-STAGE: February 15, 2008
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The state of stress in a beam of circular cross-section simply supported and loaded in the mid-span is considered as the non-axisymmetric problem of a cylinder within the framework of the three dimensional theory of elasticity. In this analysis, Dougall's stress function approach is used and boundary conditions are satisfied by use of the Fourier integral transforms. In this case, the stresses on the surface are expressed with divergent series including divergent integrals, but by eliminating the divergent terms and using Shanks' acceleration method, numerical calculations are carried out. The validity of the elementary beam theory is examined in comparison with the results thus obtained.
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Hisao HASEGAWA
1981 Volume 24 Issue 189 Pages
520-527
Published: 1981
Released on J-STAGE: February 15, 2008
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This paper is concerned with the stress concentration problem of an elastic circular shaft with an annular groove of a semicircular form under tension. The problem has been treated by several authors, but is seems that these results do not always agree with one another. In the present problem, the author's results are in fairly good agreement with Sato's results analyzed by F.E.M. and measured by strain gages. It may be also said that the form factors shown in the paper conform to Neuber's results in the case of large radii of a groove compared with the radius of the shaft and also conform to Peterson's results in the case of small radii of a groove. A fundamental principle of the method of solution employed in the paper is to superpose Green's functions for axisymmetric body force problems of a solid circular cylinder. This method can be easily applied to other annular grooves besides a semicircular one treated here.
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Osamu DOI, Naoki ASANO
1981 Volume 24 Issue 189 Pages
528-533
Published: 1981
Released on J-STAGE: February 15, 2008
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The basic equations of motion with contact-impact behavior for two bodies are formulated by the finite element method based on the principle of virtual work, in which the unknown contact-impact forces acting on contact surfaces are treated as the forces acting on surfaces of each body. Regarding two bodies as being interconnected through contact surfaces makes it possible to eliminate the unknown force components form the basic equations Then, the equations of contact motion for two bodies can be derived for various contact states. The equations of contact motion are applied to a two-dimensional analysis of longitudinal impact of two prismatic rods with an equal cross-sectional area. Although the calculated results fluctuate periodically, the mean value agrees well with that obtained by the theory of propagation of one-dimensional elastic stress wave. This method is practically applicable to elasto-dynamic contact problems.
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Kozo OSAKADA, Jiro KOSHIJIMA, Hideo SEKIGUCHI
1981 Volume 24 Issue 189 Pages
534-539
Published: 1981
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The criterion for ductile fracture strain of carbon steels proposed in the previous reports is applied to a few modes of deformation. In general, the fracture strain predicted by the criterion agrees fairly well with the experimentally obtained one. The result suggests that the fracture strain is affected to some extent by the mode of deformation which was not taken into account in the criterion. When the direction of deformation is reversed during torsion test, a sharp bend is observed in the relationship between the strain before reversal and the strain to fracture after reversal. The bend is related to the initiation strain of fracture-nuclei-growth. The fracture strain of a torsional specimen after intermediate annealing is also found to change sharply when the strain prior to intermediate annealing exceeds the initiation strain of fracture-nuclei-growth.
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Toshiaki KANEMOTO, Tomitaro TOYOKURA, Junich KUROKAWA
1981 Volume 24 Issue 189 Pages
540-546
Published: 1981
Released on J-STAGE: February 15, 2008
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The characteristics of a flow, in which the laminar boundary layer along a flat plate at zero incidence interferes in the turbulent wake behind a circular cylinder, were studied experimentally and theoretically. The main results are as follows. (1) The boundary layer flow undergoes a remarkable transition from the laminar to the turbulent region under the influence of the velocity fluctuation of the wake flow. (2) The theoretical results based on the composite velocity profile obtained by superimposed the boundary layer flow on the wake flow agree fairly well with the measured ones.
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Iwao OHTANI, Tetsuo IWAMOTO
1981 Volume 24 Issue 189 Pages
547-554
Published: 1981
Released on J-STAGE: February 15, 2008
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A new casing has been devised, in order to reduce the noise of Roots blowers caused by their unique compression process. With an extended peripheral length, the new casing gradually reverses the flow of a high pressure gas on the discharge side through the clearance between the casing and the tip of the rotor. Using a 5.5kW Roots blower, a comparative test was made between the conventional casing and this peripharal extended casing having a clearance that should cause the pressure in the closed suction chamber to rise sinusoidally. As a result, it was found that the new casing could help mitigate the pressure pulsation of a discharge gas to reduce the discharge noise by about 10 dB(A).
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Hiroshi MAKI, Yuichi IKEDA
1981 Volume 24 Issue 189 Pages
555-561
Published: 1981
Released on J-STAGE: February 15, 2008
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In order to extend availability of a float-area-type flow meter, flow rate characteristics of the float-area-type flow meter when the frequency of pulsating flow was much larger than the resonant frequency of a float in the direction of the flow were theoretically and experimentally studied. As the result it was found that the indicated float position for the pulsating flow rate was always higher than that for steady flow rate. Limits of availability were ascertained as the result of the pulsating flow measurements.
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Kotohiko SEKOGUCHI, Tohru FUKANO, Yasushi KAWAKAMI, Hideo SHIMIZU, Toh ...
1981 Volume 24 Issue 189 Pages
562-570
Published: 1981
Released on J-STAGE: February 15, 2008
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The effect of a flow obstruction was experimentally investigated on the minimum thickness of a water film formed on the outer surface of the inner tube of concentric double tubes, through an annular cross section of which air-water two-phase mixture flows vertically upward. The flow patterns concerned are slug, froth and annular flows. Two kinds of obstructions were used in this experiment ; one is a ring type obstruction and the other is a thin circular tube type spacer. The liquid film thickness is drastically decreased by the existence of a flow obstruction, i.e., to about 40 μm. The film thinning process and the dependency of film thickness upon flow patterns are found to be quite similar to those on the inner wall of a single circular tube with an obstruction . Furthermore, an increase in minimum film thickness near an obstruction is observed resulting from the existence of an upstream obstruction.
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Minoru TSUKAHARA, Takemi CHIKAHISA, Noboru MIYAMOTO, Tadashi MURAYAMA
1981 Volume 24 Issue 189 Pages
571-577
Published: 1981
Released on J-STAGE: February 15, 2008
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The authors carried out experiments in order to realize alleviation of the rapid heat generation at the initial stage of combustion simultaneously with shortening of the combustion duration by combining the injection of auxiliary fuel preceding the main injection with a retarded fuel injection timing in a precombustion chamber type diesel engine. As a result, NOx concentration was reduced remarkably without any sacrifice of the specific fuel consumption in a pilot injection under a suitable condition.
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Akio NAGAMATSU, Masaaki OOKUMA
1981 Volume 24 Issue 189 Pages
578-584
Published: 1981
Released on J-STAGE: February 15, 2008
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Forced vibrations of mechanical structures are analyzed by the reduced impedance method the authors proposed. A structure is divided into some components, and the mechanical impedances of these components are calculated by the finite element method. These impedances are reduced and combined to get a united equation of the forced vibration. The forced vibrations of a plate, a box specimen and an actual cylinder block are analyzed by this method, changing the damping coefficient and the number of the finite elements of the components. On the other hand, the steady state vibration is measured under a harmonic exciting force, and the mechanical impedance is determined form the measured wave of the force and the acceleration. The calculated results are compared with the experimental ones in order to check the accuracy of the theoretical analysis, and both results agree well with each other.
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Keijin SATO, Osamu KAMADA, Nobuo TAKATSU, Susumu MORIYA
1981 Volume 24 Issue 189 Pages
585-590
Published: 1981
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A new travelling mechanism termed a vibratory travelling element is devised. This element has many bristles standing in regular order at two different inclinations and acting as cantilever springs. First, the possibility of travelling is examined by means of the computer simulation using a dynamical model, and secondly, the travelling mode and the velocity are mainly investigated experimentally. The experimental results verify the simulation, and it seems to be possible to develop this mechanism.
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Hiroshige FUJIO, Toshio AIDA, Takayuki ARATAKE, Eiji HOSOI
1981 Volume 24 Issue 189 Pages
591-598
Published: 1981
Released on J-STAGE: February 15, 2008
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Gears made of two kinds of materials and with limited face width were quenched. In an experiment of gears made of S45C an increase of tip cylinder diameter after through-hardening, was observed with a reduction of face width. Contrariwise gears made of SCM21 showed a reduction of tip cylinder diameter after case-hardening. From those results it is clear that gear deformation after the hardening process depends on the material and dimensions of gear. Moreover this study shows a theoretical calculation method for the temperature and deformation distribution in a cylinder with limited length during the quenching process. The calculated results show good coincidence with the experimental results obtained for the test gears and the equivalent cylinder test pieces.
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