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Hiroo MIYAIRI, Masahiro NAGAI, Atsuyoshi MURAMATSU
1978 Volume 21 Issue 151 Pages
1-6
Published: 1978
Released on J-STAGE: February 15, 2008
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Acrylic resin is widely used as the denture base material, but a failure of the upper complete denture often happens during its use. Therefore, the denture base made of acrylic resin should be reinforced by something else. So, the authors have thought of improving the strength and rigidity by laminating the organic fiber reinforced plastics on the palatal surface of the denture base, which is called the canape construction. In this paper, the flexural strength, fatigue strength and the modulus of elasticity in bending of the canape construction were investigated as basic experiment. As the result, the flexural and fatigue strengths have been improved to 160% and 130% of the denture base acrylic resin, respectively. And the modulus of elasticity in bending has been improved 80%. Therefore, it seems that this new combination of materials using the canape construction might be applied well enough to the denture base.
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Hideaki KASANO, Hiroyuki MATSUMOTO, Ichiro NAKAHARA
1978 Volume 21 Issue 151 Pages
7-12
Published: 1978
Released on J-STAGE: February 15, 2008
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Theoretical results for an infinite cylinder subjected to tow diametrically opposite loads are obtained by the three-dimensional theory of elasticity. In this analysis, Dougall's stress functions are used and the numerical calculations are carried out for the concentrated loads which are the limiting case of the partially distributed loads. In this case, the stresses on the surface are expressed with a divergent series including divergent integrals, but by eliminating the divergent terms and using Shanks' acceleration method, calculations are carried out even for the surface stresses as well as the inner ones. Numerical results are presented for the distributions of stresses and displacements.
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Hiroshi NAKANISHI, Megumu SUZUKI, Minoru HAMADA
1978 Volume 21 Issue 151 Pages
13-19
Published: 1978
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A lower bound method of limit analysis of shells of revolution is proposed. The shell is assumed composed of a rigid/perfectly plastic material obeying the Tresca yield condition. The proposed method uses a part of the correct yield surface for shells of revolution, and gives statically admissible solutions. Using this method, the limit loads for two problems are calculated: (1) pressure vessels with rigid circular plates and (2) torispherical pressure vessels. The calculated results are shown in figures and compared with solutions by other methods. Further, experiments are performed with the torispherical pressure vessels, and their results are compared with the calculated results.
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Eiichiro TSUCHIDA, Kozo MAEDA, Ichiro NAKAHARA, Masao KODAMA
1978 Volume 21 Issue 151 Pages
20-29
Published: 1978
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This paper presents an exact solution for the stresses in an elasic thick plate having an eccentrically located spherical cavity under transverse bending. In the analysis six harmonic stress functions approach is used. The solution is expressed by a combination of the cylindrical and spherical harmonics in infinite integral form and infinite series respectively. The boundary conditions on the surfaces of the plate and the surface of a spherical cavity are well satisfied with the aid of the relations between cylindrical and spherical harmonics. Numerical results are given for the eccentric distance c = 0.25, 0.5 with the ratios of cavity diameter to plate thickness varying 0.05-0.45 and 0.05-0.35 respectively and the stress distributions around a spherical cavity are shown graphically.
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Akio SHINDO, Yasuyuki SEGUCHI, Osamu SHINMURA, Hiroyuki KOJIMA
1978 Volume 21 Issue 151 Pages
30-36
Published: 1978
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Incremental elastic-plastic problems are analysed numerically with respect to a straight bar under combined bending and twisting, and a thin-walled tube under tension or torsion combined with internal pressure. In both problems, the secondary effects are discussed; in the former, the solutions taking into account the secondary stresses which arise from the material compressibility in elastic region are compared with those corresponding to the incompressible material; and in the latter, the influences of the stress and strain distributions along the thickness of a specimen are examined to verify the apparent effects on the experimental yield surface.
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MASAHIRO GEN, YASUYUKI SEGUCHI, TAKUZO IWATSUBO
1978 Volume 21 Issue 151 Pages
37-43
Published: 1978
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In the evaluation of a structural reliability, it is important to seek the probability distribution of the structure, but in many cases, it is difficult to determine it for complex structures. In this paper the limit analysis of a structure with probabilistic natures is rewritten to a stochastic mathematical programming problem (i.e. chance-constrained programming problem), where it is assumed that the probability that the structure is within the yield loci is equal to the probability that the collapse does not occur, and then the probability distribution of strengths is estimated. As an example, a reinforced circular cylindrical silo subject to loading by its contents with, and the probability distribution of the strengths and the reliability of the structure are numerically calculated.
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Kiyoshi SHIMADA, Shuzo MIWA, Takafumi NAKAI
1978 Volume 21 Issue 151 Pages
44-50
Published: 1978
Released on J-STAGE: February 15, 2008
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Unbalanced vibration of a flexible rotor supported on two bearings is analysed in this paper for the case of flexible support with viscous damping. The analytical solution is obtained by using the concept of "forced mode", which makes the vibration phenomena for the system in consideration more understandable than before. Based on this solution, the condition as well as a possible procedure to balance such a rotor is theoretically demonstrated, conclusions of which are: (i) It is possible to obtain the universal state (in a practical sense) of balance of a flexible rotor which is satisfactory irrespective of its bearing properties, the magnitude of elasticity and viscous damping, through dynamic balancing and modal balancing of the rotor for the simply supported end condition, and (ii) this can be successfully be achieved by measuring shaft vibration of the rotor on flexible bearing with viscous damping.
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Hideo SAITO, Hiroshi WADA
1978 Volume 21 Issue 151 Pages
51-55
Published: 1978
Released on J-STAGE: February 15, 2008
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This paper investigates analytically the plane stress problem of flexural vibrations of an elastic beam supported by an elastic half-space and subjected to a sinusoidally varying force at the free end of the beam. Since the actual stress and displacement distributions at the interface between the half-space and beam are still unknown, we assume linear normal stress distribution and uniform shear stress distribution at the interface, and apply mean displacement and mean slope of the half-space. The dynamic effects of foundation stiffness and slenderness ratio on the response curves of the beam are presented.
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Kenzou NONAMI, Masakazu MIYASHITA
1978 Volume 21 Issue 151 Pages
56-63
Published: 1978
Released on J-STAGE: February 15, 2008
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The nonstationary vibration of a rotor with a gyroscopic effect in passing through its critical speed is studied by using the asymptotic method. In particular, the influence of a gyroscopic effect in passing through a critical speed is studied in detail on two cases, i.e., one of a constant acceleration and the other considering the interaction between the driving source and the vibration system. The effect of an internal damping on the stability is also studied. The experiments support the analysis.
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Toshihiro IOI, Ken IKEDA
1978 Volume 21 Issue 151 Pages
64-71
Published: 1978
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Main purpose of this paper is to analyse the forced vibration prevention of the vibration system with positive or negative damping by the damped dynamic absorber. The cases treated in this paper are: the case I (the alternative exciting force of a constant magnitude is acting on the mass of the main system), the case II (the alternative exciting force, of which the magnitude is proportional to the square of its frequency, is acting on the mass of the main system), and the case III (the alternative displacement is given to the foundation of main system), It is explained how the spring constant and the damping factor of the dynamic absorber are desirably optimized to make the vibration effect minimum. The optimum values in the above cases are given by the convenient empirical formulae.
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SHOJI MICHIDA, KEIZO YAMAGUCHI, TOSHIHIKO KURIOKA, YOSHIRO KAOAMI
1978 Volume 21 Issue 151 Pages
72-80
Published: 1978
Released on J-STAGE: February 15, 2008
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By using the incremental finite element method, the snap-through problem of the unit arch and that of the movable spring for the Z-type precision snap-acting switch (i.e. the microswitch) are analysis with sufficient accuracy in this report. The latter is treated as an example of the complex arch spring. Concerning the finite element formulation with beam-column elements, a new element model, the both ends of which are elastically supported on a fixed foundation, is proposed. By examining the numerical results by the method of experimental designs, some design formulae of the movable spring of the Z-type microswitch are obtained.
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SHOJI MICHIDA, KEIZO YAMAGUCHI, TOSHIHIKO KURIOKA, YOSHIRO KAGAMI
1978 Volume 21 Issue 151 Pages
81-89
Published: 1978
Released on J-STAGE: February 15, 2008
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The incremental finite element method is applied to analyze the snap-through problem of the movable spring for the V-and W-type precision snap-acting switches (i.e. microswitches). These movable springs are treated as two examples of the complex arch springs and idealized as composed of the "beam-column" elements. Calculated results are found to coincide with experimental one with accuracy enough for practical purposes. Further, by examining the numerical results with the method of experimental designs, some design formulae for the movable springs of the V-and W-type microswitches are proposed.
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Susumu MURATA, Takenori OGAWA, Masanori GOTOH
1978 Volume 21 Issue 151 Pages
90-97
Published: 1978
Released on J-STAGE: February 15, 2008
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In this paper, authors have presented a method to analyze the flow in a variable width centrifugal impeller. This analysis has been based on Hoffmeister's method and new considerations have been added to the analyses of through flow and displacement flow. Authors have applied this method to the calculation of nenviscous and incompressible fluid flow through the centrufugal impeller with thin logarithmic spiral vanes, and shown the velocity and pressure distributions on the vane surfaces and influences of the impeller width ratio on the performance of the impeller.
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Shuji TANAKA, Makoto KAIBARA, Akifumi TANAKA
1978 Volume 21 Issue 151 Pages
98-103
Published: 1978
Released on J-STAGE: February 15, 2008
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Some experiments of decay and modification of a trailing vortex, which is shed from the tip of a lifting wing are described. Flow fields of the trailing vortex are shown and the effects of the air jet injection from the wing-tip on the attenuation of the disturbances caused by the trailing vortex are discussed. When the air jet is not injected, changes in the flow fields near the trailing vortex in the flow direction are quite small and the total circulation and the disturbances due to the trailing vortex such as the large circumferential velocity, defects in the axial velocity and the static pressure are maintained in the region far downstream of the wing. When the air jet is injected, vortex filaments are distributed over a wide region and the disturbances can be suppressed to small quantities. The turbulence caused by the trailing vortex increases with the distance from the wing when the air jet is not used, but the jet injection has an effect to attenuate the turbulence.
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Sei-ichi IIDA
1978 Volume 21 Issue 151 Pages
104-111
Published: 1978
Released on J-STAGE: February 15, 2008
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In case of finite Reynolds number R
e, the second order solutions of boundary-layer equation for the flow over a circular cylinder with separated wake are investigated in the vicinity of the stagnation point. The second order effects for wall shear stress T
w due to the curvature of the cylinder and the displacement of main flow are discussed by introducing the method for higher order boundary-layer solutions developed by Van Dyke. As a results, it is shown that T
w decreases proportionally to R
e-1/2 and the effect of curvature amounts to 75 percent of the decreasing rate. Moreover, a new accurate method for solution of first order boundary-layer equation is proposed.
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Yasutoshi SENOO, Nobumasa KAWAGUCHI, Tetsuzou NAGATA
1978 Volume 21 Issue 151 Pages
112-119
Published: 1978
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Five conical diffusers with different divergence angles were tested to clarify the influences of swirl on the pressure recovery coefficients. Pressure recovery coefficients of all diffusers were improved by swirl, and the highest coefficient was observed in an 8-deg diffuser when the flow had a moderate swirl. The flow patterns in the diffusers were examined at various conditions to clarify the relationship between the swirl and the pressure recovery coefficient.
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Mitsukiyo MURAKAMI, Osami KITO
1978 Volume 21 Issue 151 Pages
120-127
Published: 1978
Released on J-STAGE: February 15, 2008
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Discharge coefficients of pipe orifices in swirling flow were measured and the results were discussed theoretically. Differential pressure across the orifices is affected by the swirling component and its amount is found to be a function of two parameters ; the rate of constriction of orifice opening and the intensity of swirling component. In a small orifice opening the differential pressure is decreased by the swirling component, and in a larger orifice opening it is increased. Relative change of the differential pressure was calculated theoretically by using a potential flow model. Distributions of velocities and pressures were measured and changes of energy and momentum of the flow through the orifices were discussed.
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Tomosada JOTAKI, Yuji TOMITA, Keio FUJIMOTO, Masaharu IWASAKI
1978 Volume 21 Issue 151 Pages
128-133
Published: 1978
Released on J-STAGE: February 15, 2008
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Using polyethylene pallets with a free falling velocity of 5.8m/s, measurements of pressure drop and solids velocity are mode in 41.2, 52.6, 66.8, 78.3 and 100.0 mm I.D. straight P.V.C. vertical pipes of length 24m up to a solids/air ratio of 43, varying air velocity from 9 to 50 m/s. A general correlation for additional pressure drop is derived, taken account of these factors. Pipe friction factors for solids are calculated and shown to be a monotonous increasing function of pipe diameter alone.
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Shigeki ARAI, Yukio TOMITA, Kouzou SUDOU
1978 Volume 21 Issue 151 Pages
134-141
Published: 1978
Released on J-STAGE: February 15, 2008
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With the development and use of such MHD devices as electromagnetic pumps in metallurgical and atomic industries, and MHD generators, the investigation of the flow of electrically conducting fluids in channels under an applied magnetic field is growing in importance. Here are reported experimental results of laminar and transition flows in a transversely applied magnetic field. Mercury is run in two types of rectangular channels, one having insulating walls, the other with insulating top and bottom walls and conducting side walls. The influence of Reynolds number, the electrical property of the side walls and the aspect rations of channels on such flows in the range of relatively low Hartmann numbers is described.
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Shuji ABE, Ryu FUJIOKA, Akira NAGASHIMA
1978 Volume 21 Issue 151 Pages
142-146
Published: 1978
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Viscosity of D
2O in the gaseous region up to 400°C and 300 bar was measured with the aid of a capillary viscometer. Existence of a negative pressure gradient at subcritical temperature was experimentally and quantitatively confirmed. Measured results of the viscosity on five isotherms were correlated into a simple empirical equation.
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Masaru HIRUMA, Shoichi FURUHAMA
1978 Volume 21 Issue 151 Pages
147-160
Published: 1978
Released on J-STAGE: February 15, 2008
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The amount of wear debris from the exhaust value seat in condensed water of exhaust gas was continuously measured by means of the R.I. method. At the same time, rotational and lateral motion of the value were measured. Then the mechanism of the exhaust value recession in using lead free gasoline as a fuel of the automobile engine was made clear as follows: Cast iron flakes were removed from the value seat and they adhered to the value surface. And then, these deposits wore off the value seat because of rotational and rolling motions of the value. Especially, during about 20 minutes after the running conditions were changed, the valve motions became more violent and the wear also increased rapidly. Thus the overall abnormal wear of the value seat was caused mainly by above mentioned transient phenomenon.
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Osamu DOI, Masao YOKOYAMA
1978 Volume 21 Issue 151 Pages
161-166
Published: 1978
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The authors have introduced a theoretical calculating formula of cutting forces in orthotropic material of wood by applying the theories of beam on elastic foundation and linear fracture mechanics. In this report, as their formula appears to be applicable to the crack type cutting in which chip is formed by crack extension from tool edge, they employ phenolic laminated sheet, unsaturated polyester resin, cast iron and coal as brittle materials for cutting experiment, and confirm their formula to be of practical use in the brittle material cutting by comparing the experimental results with the theoretical values.
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Genji YAMAZAKI, Hirotaka SAKASEGAWA, Takeshi KAWASHIMA
1978 Volume 21 Issue 151 Pages
167-171
Published: 1978
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A flow-shop has K machine groups in tandem, where the k-th machine group consists of a single server having variable processing-time, or of m
k parallel servers, each having the same constant processing-time. The allowable queue sizes in front of all machine groups except the first may be arbitrary. We prove the reversibility of the production rate in the model. And we propose a new technique using this property to estimate the production rate precisely by some numerical methods.
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