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Hideharu FUKUNAGA, Koichi GODA
1985 年 28 巻 235 号 p.
1-6
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
The present paper deals with microstructures and segregations of silicon carbide fiber reinforced copper-added aluminum and aluminum -added magnesium alloy composites, fabricated by squeeze casting, and refers to the effect of the microstructure on the tensile strength of composites. The results obtained are as follows: The results obtained are as follows: 1) Microscopic examination showed a solute element rich layer with semicircle surrounding was locally formed on fibers in the composites, whichever matrix alloy was used. The layer was identified as a eutectic constitution by EPMA decreased in thickness and area fraction, and for the case of 1% copper-aluminum matrix, no copper-rich layer was detected. 2) The appearance of the layer decreases the tensile strength of composites because of its brittleness.
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Masaki MORISHITA, Yasuhide ASADA, Akiyoshi ISHIKAWA
1985 年 28 巻 235 号 p.
7-12
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
A series of creep-fatigue tests conducted with 304 stainless steel at 650°C in a very high vacuum environment of 0.1 μPa were subjected to evaluation based on damage concept relating to an inelastic deformation behavior of the material. In the model, a damage is separated into two components of time-dependent and -independent. An inelastic strain is separated into time-dependent and -independent strain parameters. Damage components are related to inelastic strain parameters to give damage rate equations in which material constants are determined from experiments.
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Toshio Jingu, Koji Hisada, Ichiro Nakahara, Shuro Machida
1985 年 28 巻 235 号 p.
13-19
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
It is the purpose of this paper to analyse the problem of stress waves in a circular disk subjected to two equal and opposite concentrated impact loads at the end points of a diameter. The solution is based on the stress function approach and the Laplace transform method to a two dimensional non-axisymmetrical dynamic problem. The Laplace inverse transforms are accomplished by the evaluation of residue. The results of numerical evaluation are shown graphically as the variation of displacement and stress versus time. We discuss the relationship between the time dependent displacement or stress, and the arrival of wave.
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Masachika NAITOH, Masashi DAIMARUYA
1985 年 28 巻 235 号 p.
20-25
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
The purpose of this paper is to examine not only qualitatively but also quantitatively the influence of a rise time of longitudinal impact on the propagation of elastic waves in a bar. The adequacy of application of Love's theory for the propagation of longitudinal elastic waves to this problem is discussed by means of the simultaneous measuring of both axial and radial strains at the same stations along a bar. Theoretical results based on the Love theory predicted that, as the rise time of impact velocity increases, the effect of lateral inertia on longitudinal waves decreases and then the oscillatory wakes of it become negligibly small. Experimental results for a steel bar agreed well with the theoretical results. Moreover, as an example of appication, the experimental measurement of the dynamic yield stress by using a stress bar was analyzed.
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Katsuhiko WATANABE
1985 年 28 巻 235 号 p.
26-33
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
The conservation laws related to path independent integrals are discussed based on the conservation of energy and the principle of virtual work, and the equality of these laws is proved. Through the discussion of the conservation laws, it is also shown that the concept of energy momentum tensor which can be applied when limited constitutive equations are assumed can be extended to the useful concept which has no limitation on constitutive equation. Secondly, an expression of crack energy density by path independent integral is given based on the above conservation laws and the relations to other known path independent integrals (J-integral and J^
- -integral) are discussed. The concept of crack energy density was previously proposed by the author as a fundamental parameter in fracture mechanics and it is the purpose of the present paper to obtain a path independent expression of crack energy density for evaluating its value.
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Masahiro ICHIKAWA, Tohru TAKAMATSU
1985 年 28 巻 235 号 p.
34-39
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
Initiation of stable crack growth under Mode II loading in center cracked specimens of 2024-T3 aluminum alloy is investigated using the apparatus devised previously by the authors. This apparatus makes it possible to conduct Mode II testing on a specimen which has the same geometry as that for Mode I testing. It is shown that the stress intensity factor at initiation of stable crack growth, (K
i)n, is constant irrespective of the specimen width for W≧ and decreases as W decreases for W<Wo, where Wo is a certain specimen width. This tendency is quite similar to our previous results about Mode I loading. Finite element analysis is carried out in order to examine if J-integral is applicable. It is shown that the specimen width dependence of (K
i)n is well explained by (J
i)m=constant criterion. This result is similar to Kitagawa and others' analysis for Mode I loading.
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Yoshihisa MINAKUCHI, Kanae YOSHIMINE, Takashi KOIZUMI, Takanori HAGIWA ...
1985 年 28 巻 235 号 p.
40-45
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
A quantitative measurement of contact pressure by means of ultrasonic waves has been proposed to measure the contact pressure distribution between two elastic beams. At first, in a new proposed calibration method, the relation between mean contact pressure and sound pressure of reflected waves is obtained by using calibration blocks made of the same material and height as the beams. After such preparation, both sides of the laminated beams are compressed under locally uniform pressure, and the sound pressure of reflected waves is measured. From these relations, the contact pressure in beams is directly obtained. It is clarified that the experimental results agree approximately with the theoretical ones and the proposed ultrasonic method is practically useful.
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Ryuichiro YAMANE, Shuzo OSHIMA, Mamoru TAKAHASHI, Hideaki TAMAKI
1985 年 28 巻 235 号 p.
46-53
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
The static and dynamic properties of a pseudo-shock in a radial supersonic flow between two parallel plates were investigated. The length and pressure recovery of the pseudo-shock were smaller than those in a constant-area duct. Pressure fluctuations at two different points along the radius were simultaneously measured and were statistically correlated, so that the propagation of pressure fluctuation was obtained. They had tow main frequencies, high and low ones, which propagated in different directions.
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Munekazu OHMI, Manabu IGUCHI, Hirotoshi KAWABATA, Makoto TAKANO
1985 年 28 巻 235 号 p.
54-61
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
Velocity distribution measurements in an oscillatory pipe flow through a plate orifice are made with air over Reynolds numbers 3590 to 15300 at a frequency of 1.03 Hz. The Reynolds number is based on the amplitude of cross-sectional mean velocity and the pipe diameter. The velocity distribution in a laminar-like phase can be approximated by a laminar analytical solution presented so far, while in a turbulent phase it agrees well with that in a turbulent steady flow. A method of measuring a reattachment length, which is applicable to an unsteady flow as well, is proposed. The reattachment length in an oscillatory flow measured by this method is insensitive to acceleration and nearly constant under the present experimental conditions.
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Hiroshi TOKUNAGA, Yoshitsugu YASUI
1985 年 28 巻 235 号 p.
62-67
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
For the calculation of two-dimensional turbulent shear flows by the discrete vortex model, a numerical scheme by which motions of a system composed of many vortices can be calculated accurately is proposed. It is verified that the rolling-up process of the vortex sheet presented by Rosenhead is calculated accurately by this scheme. The present method is applied to the study of an unsteady turbulent shear flow which is represented by two hundred vortices with random vortex strengths and with initial random locations given by random numbers. As a result it is found that a coherent structure with a spiral form is realized in the turbulent flow, and the thickness of the turbulent shear layer increases linearly with time. It is shown that the calculated mean velocity, longitudinal and transversal turbulent intensities, and the Reynolds stress develop with time in the self-similar manner governed by the length scale of the turbulent shear layer thickness.
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Tadao FUJIWARA, Koji HIROSE
1985 年 28 巻 235 号 p.
68-73
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
A laminar flow induced by suction at the center of a circular vessel and the trajectory of a spherical particle setting freely in it are studied with a view to developing a highly effective circular settling tank. The numerical results about the flow fields obtained by solving the vorticity transport equations in difference form show that recirculation flows occur along the lateral wall of the vessel, and the flow characteristics depend on the depth of the influent weir rather than on the average velocity in it. For the flow fields, agreement with the experimental velocity vectors obtained with the aid of dye-method is generally good. The trajectory of a particle in the vessel is simulated by the use of a calculated flow field. The trajectories of the particles with influent water are similar to those of an ideal plain settling basin, but the trends about requird time to settle are reversed.
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Ryoichi S. AMANO, Shunichi SUGIYAMA
1985 年 28 巻 235 号 p.
74-79
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
A study is reported on the heat transfer characteristics of a flat plate when an axisymmetric air jet impinges normally on to the plate. The two-dimensional Navier-Stokes equations are solved by using the kε Boussinesq Viscosity Model (BVM). Refined wall function relations are used for the evaluation of the k-equation. The turbulence Prandtl number is proposed as a function of the local ratio of turbulent energy production to energy dissipation rate. Predictions by the present model show generally good agreement with the experimental data.
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Hideomi FUJITA, Heishichiro TAKAHAMA, Tadao KAWAI
1985 年 28 巻 235 号 p.
80-87
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
For a circular cylinder of diameter D=50mm attached tripping wires in cross flow, the pressure distribution around it, the drag coefficient and the Strouhal number were measured at a Reynolds number of Re=5×10
4, varying the diameter of the wires d=0.1 to 2.0 mm and the angle θ from the frontal stagnation point to the wire from 15 to 90 degrees. The pressure distributions were classified into three patterns. When the distribution was similar to that which should be observed in the critical state (i.e., at about Re=8.5 ×10
5), the drag coefficient of the cylinder with tripping wires of d = 0.3 to 2.0 mm was reduced to about a half that of a bare cylinder and then the tripping wires could be considered effective. The range of θ in which the wires brought about reduction in drag was rather narrow, and when the angle θ was over this range, the drag rapidly exceeded that of the bare cylinder and the pressure distribution also changed in shape.
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Kazuyasu MATSUO, Shigetoshi KAWAGOE, Keisuke SONODA, Toshiaki SETOGUCH ...
1985 年 28 巻 235 号 p.
88-93
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
In the case of moist air or steam rapidly expanding in Laval nozzles and condensation occurring in the supersonic section of the flow, if the heat released by condensation exceeds a certain quantity, the flow becomes unstable and a periodic flow oscillation occurs. In the first report, an empirical relation for the frequency of the periodic flow was presented and the range of oscillations was clarified. In the present paper, the flow oscillation has been examined experimentally for the case of rapid expansion of moist air, using a Ludwieg tube and a super sonic indraft wind tunnel. As the result, the effects of the initial relative humidity of the moist air and the nozzle geometry on the amplitude of pressure oscillation have been clarified. Furthermore, based on the experimental results, the mechanism of the flow oscillation has been discussed.
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Hayato MAEDA, Ryotaro IZUMI, Hiroshi YAMASHITA, Sadamu KAGA
1985 年 28 巻 235 号 p.
94-100
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
A rotating condenser with a scraper is considered as a new means to be used in condensing heat transfer augmentation. In the previous papers, we analyzed the case where the condensate film on a vertical and a horizontal rotating cylinder was scraped off mechanically by a plate, and we clarified the condensate states and the enhancement due to scraping. In this paper, we report on the experimental results about the condensation of refrigerant R-11 corresponding to the above analysis. The distributions of cylinder surface temperatures and the mean heat transfer coefficients are obtained. The effects of speed of rotation and temperature difference between vapor and condenser surface are made clear. The enhancement due to scraping is discussed in terms of the mean Nusselt number ratio and compared with analytical results.
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Takeo SAITOH, Kozo FUKUDA
1985 年 28 巻 235 号 p.
101-107
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
A three-dimension simulation for the urban heat island in Sendai with consideration of the land and sea breeze effects was performed. The governing equations were solved numerically under the assumptions of hydrostatic equiriblium, Boussinesq approximation, boundary layer approximation, and equivalent turbulent eddy diffusivity for energy and momentum, and so on. The computed results obtained from this study indicate that the urban heat island has also been formed in Sendai. The computed maximum wind velocities of the sea and land breeze were in agreement with the observed data. Further, the three-dimensional thermal structure and the flow patters were clarified in detail.
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Yoshiteru ENOMOTO, Shoichi FURUHAMA
1985 年 28 巻 235 号 p.
108-116
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
The optimum thin film thermocouple in terms of materials, shape and dimensions has been determined as follows. Equations of different element method capable of determining the temperature distribution in such a thermocouple are introduced in order to obtain the temperature distribution by which the combustion gas temperature and heat transfer coefficient affect the thermocouple under steady state and unsteady state conditions. Further, effects of thermophysical properties and dimensions of materials constituting the thermocouples have been studied. On the other hand, thermocouples made of different materials and in different shapes have been trially produced and embedded respectively into the piston of a 4-stroke gasoline engine. Actual measurements of such thermocouples proved the validty of calculated results, and it has been demonstrated that the above mentioned thermocouples have an adequate durability under high speed/high load conditions.
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Shin TAKAHASHI, Katsuyoshi SUZUKI, Tadashi KOSAWADA
1985 年 28 巻 235 号 p.
117-123
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
In this paper, free vibrations of truncated conical shells with variable thickness are studied by two methods. One is the method to use the stress-strain relations of the classical theory and the other is to use the three dimensional Hooke's law on the assumption that displacements are linear functions of thickness of shells. In both studies, Lagrangians of vibrations are obtained, equations of vibrations and boundary conditions are deduced from stationary conditions of Lagrangians and strict solutions are calculated in a form of series. These are, also, compared with equations and numerical result of the improved theory published by authors before.
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Youichi SASAKI, Hiroshi NIWA
1985 年 28 巻 235 号 p.
124-131
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
In order to meet the qualifications for design of piping with respect to the earthquake inputs which are required to consider increment of the intensity, earthquake resistant design will be required to consider a piping component behaving in both its elastic and plastic regions. The elasto-plastic vibration analysis of piping is extremely difficult to perform in a generalized form. So, a piping simple in configuration was used to find elasto-plastic properties when it was vibrated. Two methods were devised for approximate elasto-plastic vibration analysis of complicated piping structures considering the elasto-plastic properties obtained from the vibration tests using a piping simple in configurations: one using a modal analysis methods and the other using equivalent linear damping. Calculated results obtained by applying these methods were compared with experimental data for verification of validity of these methods.
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Tatsuhiko AIZAWA
1985 年 28 巻 235 号 p.
132-138
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
The flow-induced vibrations often cause severe troubles in nuclear reactor components, and hence mechanical engineers must make coupling eigenvalue analyses taking into account some interactions between structures and fluids. In this type of problems, natural frequencies and their associated modes should be calculated with sufficient accuracy, and for such purposes finite element method is usually a convenient tool. However, since conventional methods increase computer costs, more efficient algorithms are necessary for practical design analyses. In this paper we will propose an interation perturbation method to treat such eigenvalue problems. Since proposed method only need eigenpairs for uncoupled problem of structure, necessary ammount of computations reduces, and we can utilize usual finite element solvers installed in many program codes. To see effectiveness of our method in coupling problems, some numerical results are given for free vibrations of a beam submerged in water chamber.
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Keiji YOKOSE, Katsuhide THUCHIYA
1985 年 28 巻 235 号 p.
139-147
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
We analysed theoretically the lateral forced vibrations observed in a high speed truck when it runs on a rail with sinusoidal irregularity, assuming that the truck has spring and friction in series against truck turning. The analysis revealed that the running stability of truck is affected by various factors: the wheel tread conicity, the rotational stiffness of truck, the friction of side bearers, the creep coefficient, the viscous damping against truck turning, the flange clearance between the wheel and the rail and the lateral stiffness of rail and so on. Then, we made clear that the wheel tread conicity is one of the most important factors to prevent the lateral forced vibrations caused by rail irregularity, though for its prevention from practical point of view, it will be desirable to obtain an adequate restoring force against truck turning. The calculated results will be helpful for designing of the high speed trucks.
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Teruo IGARASHI, Makoto GOTO, Akira KAWASAKI
1985 年 28 巻 235 号 p.
148-154
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
Collision is one cause of mechanical sound. Impact sound occurs from an immense variety of sources, and may cause serious problems when it occurs to an objectionable extent in machines, structures, and the like. In view of the troublesome nature of impact sound, a series of studies have been undertaken in order to find a way to reduce it. This first report concerns the impact sound that is produced by the collision of a ball against a plate. Simply, a ball attached with a force transducer was collided with a square steel plate suspended freely, and the resulting impact sound and the pulse-like contact force occurring between the ball and the plate were measured simultaneously. Different kinds of ball materials and balls of differing diameters were tested at varying impact velocity, and the impact sound and contact force waveforms were observed and investigated through real time frequency analysis. As a result, the characteristics of impact sound have been clarified, providing an insight into the mechanism of its occurrence.
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Yoshio HARUYAMA, Atsunobu MORI, Tsuneji KAZAMAKI, Haruo MORI, Tadayosh ...
1985 年 28 巻 235 号 p.
155-161
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
Based on the Navier-Strokes equations in which the pressure is assumed to be constant across the film thickness, various approximate solutions and an exact one for the dynamic performance of externally pressurized infinitely long thrust bearings in a laminar flow regime are presented under the assumption of a small harmonic vibration. From comparison of the approximate solutions with the exact one, it is concluded that some kind of averaging approach in which a part of the time dependent term is treated exactly while the other inertia terms are averaged out across the film thickness gives close approximations in a wide range of designing conditions, and that the other kind of averaging approach in which all the inertia terms including the time dependent term are averaged out across the film thickness gives fairly good approximations.
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Tsuyoshi TABATA, Saiji MASAKI, Kou AZEKURA
1985 年 28 巻 235 号 p.
162-167
発行日: 1985年
公開日: 2008/02/15
ジャーナル
フリー
Multiple stage butt welding is attempted. The advantage of this welding is that bonding can be accomplished with a small load and a small deformation by selecting a proper initial height and a proper height reduction in each stage. The effects of the virgin surface ratio and the normal pressure at the bonding surface on the bond strength are investigated. The advantage of the multiple welding is explained by those two parameters. The bond strength is significantly depending on the virgin surface ratio. When the virgin surface ratio is high, the normal pressure is comparatively low, namely, nearly the same pressure as the tensile strength of the base metal.
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