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Hideaki NAKAYAMA, Yukio KANAYAMA, Masahiro SHIKIDA, Tsuneshichi TANAKA
1984 Volume 27 Issue 234 Pages
2599-2604
Published: 1984
Released on J-STAGE: February 15, 2008
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Impact fatigue crack growth behaviors were investigated by using 2017-T3 aluminum alloy, one of the representative f.c.c. metals for mechanical structure, as an experimental material under the stress ratios R=0 and -1. Results are discussed in comparison with those obtained under non-impact fatigue done under the same stress ratios. It is made clear, on log da/dN-log K
max diagram, that da/dN in impact fatigue is higher than that in non-impact fatigue under both stress ratio conditions. Furthermore, such a discrepancy in da/dN due to the difference in the stress condition does not disappear in the evaluation done based on the effective stress intensity factor range ΔK
eff. And, peculiarities of impact fatigue crack growth behavior obtained in this study well resemble those for low carbon steel demonstrated previously by the authors. It is concluded that the effect of the compressive load in impact fatigue loading of R=-1 on da/dN is smaller than that in non-impact fatigue.
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Kazuo TAKAKUDA, Yasushi TAKIZAWA, Takashi KOIZUMI, Toshikazu SHIBUYA
1984 Volume 27 Issue 234 Pages
2605-2610
Published: 1984
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The transient dynamic boundary value problems of elastic bodies with cracks are formulated in the forms of the integral equations. In particular, the equations for anti-plane problems are worked out in detail.Several numerical calculations are carried out and the variations of the stress intensity factors with time are clarified.for the SH step-stress waves which are incident on one or two Griffith cracks in an infinite body.
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Kazumasa MORIYA
1984 Volume 27 Issue 234 Pages
2611-2618
Published: 1984
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A special element that simulates elastic behavior near an elliptic hole has been developed for the finite element analysis of local stress concentrations arising from elliptic holes, notches, fillets and cracks. The formulation is based on Laurent series expansion technique and hybrid finite element model. The present element serves as a bending element as well as an in-plane one without modifying the computer program. It is an efficient mesh reducer and it gives accurate stress distribution in the near-field region. When one axis of elliptic hole is set at zero, the element becomes a crack element with embedded stress singularity and the stress intensity factors K
I, K
II or K
B, K
S are directly obtained as the sum of the internal parameters. Numerical example includes in-plane stretching and out-of-plane bending of plates with a variety of holes, notches and cracks.
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Mitsuyuki KOBAYASHI, Ohmi MIYAGAWA, Jinichiroh TAKAHASHI
1984 Volume 27 Issue 234 Pages
2619-2626
Published: 1984
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Crack propagations under creep condition at 700°C were investigated about two austenitic steels with different levels of ductility. Creep crack was found to grow as a result of creep deformation at the crack tip regardless of ductilities of materials used. It was also found that V/2l, where V^^· is notch opening displacement and 2l is crack length, has a nearly constant value during crack propagation with certain materials under a certain testing condition, and that creep crack growth rate can be expressed by the following equation: d(2l)/dt=V^^·/θ, where V is notch opening displacement rate and θ=V/2l. All data obtained, namely, d(2l)/dt, V^^·, θ, showed the validity of the above expression. It is demonstrated that this expression will be introduced by applying COD criterion to creep crack propagation.
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Minoru HAMADA, Yoji SHIBUTANI
1984 Volume 27 Issue 234 Pages
2627-2634
Published: 1984
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For bending problems of a circular plate with many circular holes is presented in this study a method of solution in which the general solution for the biharmonic equation in the polar coordinates is recurrently used until all boundary conditions are satisfied. This method is used to solve bending problems of a circular plate with one circular hole in eccentric position or with two circular holes of equal diameters in symmetric position. Two loading conditions are assumed; bending moment distributes uniformly at the outer edge of the plate, and the load concentrates at its center. As for the boundary condition, it is assumed that the edges of the holes are free and that the outer edge of the plate is simply supported for the first loading condition and simply supported or clamped for the second loading condition. Calculated results are indicated in some diagrams which are considered useful in design of thin-walled structures.
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Toshiyuki SAWA, Hiroyuki KUMANO
1984 Volume 27 Issue 234 Pages
2635-2642
Published: 1984
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In this paper, discussion is made on a contact stress distribution of bolted joints in the case where a rectangular metallic flat gasket is interposed between two T-flanges. Replacing gasket and T-flanges by finite strips, the contact stress distribution is analyzed using two-dimensional theory of elasticity. By numerical computations, effects of the thickness and the stiffness of gaskets on the contact stress distribution are shown. Next, the force ratio of bolted joints with gaskets, which is the ratio of an increment of bolt axial force to a load, is analyzed. With an application of the load the bending moment is produced in bolts. By taking this bending moment into consideration, the maximum stress produced in the bolts is also analyzed. Experiments are performed to verify these analyses. Numerical results are in a fairly good agreement with experimental ones.
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Kazuo TAKAKUDA, Kenji AOYAGI, Toshikazu SHIBUYA, Takashi KOIZUMI
1984 Volume 27 Issue 234 Pages
2643-2650
Published: 1984
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Steady state thermal stress problems of a bonded dissimilar medium, which has an external crack on the interface and is subjected to uniform temperature change or heat flow from infinity, are analysed by the complex function method. The distributions of displacements and stresses on the interface are presented as closed form solutions, and shown in figures.
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Toshikazu SHIBUYA, Takashi KOIZUMI
1984 Volume 27 Issue 234 Pages
2651-2657
Published: 1984
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A contact problem of an elastic half space with an adhered rigid punch under tension is considered on the basis of the three-dimensional theory of elasticity. The behaviour of the adhesion is approximated by a combination of tension and shear springs. The normal and shearing stresses on the adhesive plane of the half space are expressed by Jacobi polynomials. This mixed boundary value problem is reduced to solving two infinite systems of simultaneous equations. The distributions of stresses and displacements on the surface of the half space are illustrated in various cases of the adhesion. The effect of the adhesion on these results is discussed in detail.
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Yoshihiko SUGIYAMA
1984 Volume 27 Issue 234 Pages
2658-2663
Published: 1984
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Stability of a cantilevered system of articulated pipes conveying fluid is studied theoretically and experimentally by considering models having two degrees of freedom. The system is nonconservative and becomes subject to flutter-type or divergence-type instability depending on the system parameters. Firstly the effect of an intermediate lateral spring support on the stability is investigated to show that an additional spring support at the discharge end can be destabilizing. Secondly the combined effect of a spring support and a lumped mass is discussed. It is shown that the stability analysis by neglecting internal damping may result in an erroneous flutter prediction, especially when a big lumped mass is attached to the nonconservative system at its free end. Finally a set of experiments were conducted to verify the theory. Agreement between theory and experiment was satisfactorily good.
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Masaichiro SEIKA, Seiichiro KITAOKA
1984 Volume 27 Issue 234 Pages
2664-2669
Published: 1984
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A copper foil tested is made by tearing off electrodeposited copper on the surface of a stainless steel plate. The foil is about 12μm in thickness. Foil gauges are made by splitting the foil into many pieces in a rectangular for 9 of 2mm×30mm and they are attached to tapered rods of carbon steel which are used as the calibration test specimens subjected to cyclic torsion. When the foil is prestrained, preheated, and left at room temperature for a long time, the effects on the calibration values of the foil gauges are inspected in detail. On the basis of the above results, the methods of improving the sensitivity of the foil gauges are discussed.
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Yoshinobu MOTOHASHI, Takao SHIBATA
1984 Volume 27 Issue 234 Pages
2670-2679
Published: 1984
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Some phenomenological equations to hold among creep parameters of superplastic materials have been derived from a mechanical equation of state for superplasticity. A constant tensile-load creep test was carried out for Al-Zn eutectoid-base alloys to verify these equations. The equations agreed fairly well with the experimental results. Principal results obtained are as follows: Steady state creep disappears under the constant load. Accelerated creep accounts for most of creep strain. The relation between creep strain and time, and the time to rupture will be obtained if the minimum creep strain rate and m-value are known, where m is the strain rate sensitivity.
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Masafumi SENOO, Ikuya FUJISHIRO, Motohisa HIRANO
1984 Volume 27 Issue 234 Pages
2680-2686
Published: 1984
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To discuss the elastic properties of aluminum, the variations of the crystal energy at OK with the (100) lattice deformations are evaluated by means of the pseudopotential methods based on the model potential proposed by the authors previously. A distinction is made between the mechanical behavior of a face centered cubic (fcc) lattice in (100) loading (i.e. transverse stresses are zero) and in (100) deformation (i.e. transverse strains are zero). The fcc-bcc transitions and the elastic instabilities associated with the deformations are briefly discussed. Some elastic constants of aluminum at OK are calculated. The stress-strain relations for large elastic strains up to the theoretical tensile strength are presented.
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Kenji KANEKO
1984 Volume 27 Issue 234 Pages
2687-2693
Published: 1984
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A practical new plastic constitutive model is presented on the basis of many experimental facts for initially anisotropic metal after various prestrainings. This model has two surfaces which bound an elastic region. a transitional hardening region and a steady hardening region with respect to elasto-plastic behavior in a five dimensional deviatoric stress space. The surface G which represents the elastic region moves rigidly according to the newly presented rule. The surface G which distinguishes the transitional hardening region from the steady one moves in the direction of the stress vector and transforms its shape. The associated flow rules are adopted with the two surfaces in determining a corresponding plastic strain increment to a stress increment. The modified hardening coefficients are used when the loading point moves in the transitional hardening region. Applications of this constitutive model to some concrete examples will be presented in some following reports.
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Michio KURASHIGE
1984 Volume 27 Issue 234 Pages
2694-2697
Published: 1984
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The compressive strength or a cross-ply composite laminate consisting of fiber-reinforced elastic layers was analyzed on the basis of the ideal fiber-reinforced composite theory. Instead of the conventional traction continuity conditions, jump conditions at the layer interfaces involving singular stresses due to fiber-inextensibility were successfully applied. The dependence of the compressive strength on buckling wavelengths and the effects of rigidity and thickness of bonding layers were represented by curves.
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Hideo KIMOTO, Tatsuzo HIROSE, Yoshiyuki TSUDA
1984 Volume 27 Issue 234 Pages
2698-2705
Published: 1984
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In this report, in connection with the cavitation microjet, the behavior of a model microjet is photographed by a high-speed camera. The stress fringe propagating in a photoelastic material is also photographed, when the model microjet hits the material. From this experiment, it is revealed that the jet diameter of more than 0.6mm is necessary to generate the stress fringes in the impact velocity range of 40-140m/s. On the other hand, when a water layer exists on a solid wall, the following happens ; an impulsive pressure acts on the solid wall, when a jet whose diameter is 1.3-1.7mm hits the water layer surface and the solid wall. For a jet whose diameter is 1.0-1.2mm it acts on the solid wall, when the jet hits the water layer surface in case of the water layer thickness Th≲1.5mm, and while the jet front moves through the water layer in case of the thickness Th≲1.5mm.
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Toshihiro TAKAMI, Kouzou SUDOU, Masaru SUMIDA
1984 Volume 27 Issue 234 Pages
2706-2713
Published: 1984
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A pulsating laminar flow in a circular curved pipe is analyzed numerically, changing a flow rate ratio and a nondimensional frequency parameter. A time-dependence of internal mechanism is made clear, such as velocity profiles, distributions of wall shear stresses and others. A pressure gradient, important in engineering, is calculated on the basis of these results. Also, the pressure gradient of the pulsating flow is calculated approximately by assuming the quasi-steady state and taking an unsteady inertia force into account. The approximate result is compared with the numerical result for a mean value, an amplitude value and a phase difference of the pulsating pressure gradient.
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Masaru SUMIDA, Kouzou SUDOU, Toshihiro TAKAMI
1984 Volume 27 Issue 234 Pages
2714-2721
Published: 1984
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A pulsating flow in circular curved pipes is investigated experimentally. The experiment is executed in the region from the laminar flow to the turbulent one. Pressure drops are measured under the conditions of various frequencies, flow rate ratios and radii of curvature of the pipes. The experimental results are reported on the time-mean value, the amplitude and the phase difference of the pressure gradient and the power loss. These results are in good agreement with the approximate ones which are derived under the assumption of a quasi-steady flow.
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Manabu IGUCHI, Munekazu OHMI, Hiroshi NAKAJIMA
1984 Volume 27 Issue 234 Pages
2722-2729
Published: 1984
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Loss coefficients of the commercial 90 deg. screw elbow of Japanese Industrial Standards (JIS B 2301) whose nominal size is 11/4 in, are measured under the steady and pulsatile flow conditions. Effects of the cross-sectional area ratio of elbow to pipe and of the axial velocity distribution at the entrance of the elbow on loss coefficient are investigated in steady flows, and the appicability of Ito's estimation for elbow losses is discussed. The instantaneous and time-averaged loss coefficients are defined and evaluated experimentally in pulsatile flows. A frequency range where the turbulent quasi-steady relation for loss coefficient holds is determined on the basis of the present experimental results.
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Tsutomu NOZAKI, Masahiro NAKASHIMA, Keiji HATTA
1984 Volume 27 Issue 234 Pages
2730-2738
Published: 1984
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According to the experimental results about the jet flow issuing from the nozzles contracted on two sides and on four sides into the region bounded by two parallel flat plates, behavior of the flow depends on the nozzle shape and the initial turbulence intensity considerably. The variance and the degree of deformation of the velocity profile between the flat plates and the displacement thickness of boundary layer developed on them are newly introduced in this paper. By using these measures, it has been found that the extent of the secondary flow induced by the flat plates can be estimated quantitatively. Furthermore, the velocity profile of a bounded jet in the streamwise direction is similar to that of a two-dimensional jet approximately regardless of the distance from the bounding plate, except for a flow with small initial turbulence intensity with the nozzle contracted on all sides.
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Tsuneo AZUMA, Tatsuroh HOSHINO
1984 Volume 27 Issue 234 Pages
2739-2746
Published: 1984
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This paper describes an experimental study of the laminar-turbulent transition in the radial flow of a thin liquid film on horizontal plane. The film flow was obtained by a water discharge from the thin cylindrical opening formed by a circular nozzle and a flat glass plate. The transition mechanism could be clearly observed in a visual observation using a stroboscope, since a turbulent motion in the thin layer of water disturbed the water surface. A sequence of experiments revealed the existence of a critical discharge Reynolds number Re
t, cr, based on the equivalent length of opening, above which the transition takes place. The relation between Re and the dimensionless radius r
t* of the point of transition and the relation between r
t* and the local Reynolds number Rer based on the film thickness at r
t are established.
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Tsuneo AZUMA, Tatsuroh HOSHINO
1984 Volume 27 Issue 234 Pages
2747-2754
Published: 1984
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The radial flow of a thin liquid film is studied experimentally. The liquid film was obtained by a water discharge from the thin cylindrical opening formed by a circular nozzle and a flat plate. The film thickness was measured by means of a point gauge method. The experimental results about laminar flow are compared both with the theory of Watson and with the approximate solution for a film flow formed by a water jet falling vertically onto a horizontal plane, by using an equivalent length of opening instead of a radius of water jet. About the liquid film in which the transition from laminar to turbulent flow occurs, the approximate solution for turbulent region is compared with experimental results.
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Tsuneo AZUMA, Tatsuroh HOSHINO
1984 Volume 27 Issue 234 Pages
2755-2762
Published: 1984
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The radial flow of a thin liquid film, formed by water discharge through a small cylindrical opening between a circular nozzle and a horizontal plate, is studied experimentally. The velocity profile in a thin liquid film was measured with the aid of Laser Doppler Velocimeter. The results show that a boundary layer gradually grows in the downstream direction and finally the whole flow merges into a boundary layer, and that the transition from laminar to turbulent flow occurs when the discharge Reynolds number is large. The experimental results about the process of the flow development were compared with the theoretical values calculated by means of boundary layer theory.
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Tsuneo AZUMA, Tatsuroh HOSHINO
1984 Volume 27 Issue 234 Pages
2763-2770
Published: 1984
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The occurrence of the instability of a radial flow of thin liquid film is investigated. Two regions of flow field were considered. One is the region in which a boundary layer grows in a downstream direction, and the other is the region in which the whole flow is a boundary layer. For the former region, Orr-Sommerfeld equation was solved numerically by means of a modified Kaplan method, with the assumption of Blasius's and Watson's velocity profile. For the latter, O-S equation was replaced by a difference system, and solved taking account of the free surface condition for Blasius's and Watson's profile. In experiments, the wall pressure was measured, which was followed by spectral analysis. The pressure fluctuation frequency due to the disturbance wave was compared with the linear stability theory.
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Eiji HIHARA, Takamoto SAITO
1984 Volume 27 Issue 234 Pages
2771-2778
Published: 1984
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We investigated a horizontal two-phase flow transition from separated flow to slug flow without a phase change. A transition model is presented in this paper, based on the experimental results obtained in the air-water system. The model is derived from the growth condition of a wave on a stratified water layer. It agrees reasonably well with Mandhane's map of flow patterns. If disturbances enter the system, the slug flow transition is sometimes enhanced. To examine this transition enhancement, a test tube was attached to a water tank with a weir to regulate the initial water depth in the tube. When a water slug flows out of the tube, a bore goes upstream in the tube, and occasionally causes formation of a next slug. The theoretical model is used to predict the conditions of continual slug formation. The hydrodynamic behavior of slug flow is also examined.
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Ato KITAGAWA, Toshio TAKENAKA, Yuichi KATO
1984 Volume 27 Issue 234 Pages
2779-2786
Published: 1984
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A technique of hydraulic pressure pulse series generation by means of oil hammer is discussed. It is confirmed experimentally that a stable pressure pulse series can be obtained in a pipe, one end of which is attached to a rotary valve which controls a flow to be periodically off and on. The results of numerical calculation show good agreement with the experimental results. The pulse pressure is amplified by a booster piston, and the amplified pressure in the booster chamber runs up to about 140MPa at a frequency of 15.2Hz. It is expected that the frequency of the pulse series can be heightened by adopting a shorter pipe and the pulse pressure can be raised by increasing the amplifing ratio of the booster piston. The technique of pressure pulse generation applying an oil hammer is practical enough for generating a high frequency and high pressure pulse series.
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Takao KAWAMURA, Munihiko HIWADA, Ikuo MABUCHI, Masaya KUMADA
1984 Volume 27 Issue 234 Pages
2787-2794
Published: 1984
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In order to obtain the fundamental data on the high performance roughened heating surface, we tried to clarify the augmentative effects of a three-dimensional protuberance, whose height was the same order as boundary layer thickness. In this paper, the local heat transfer characteristics and flow field around a single and finite length circular cylindrical protuberance have been investigated experimentally, under the codition of H/D=0. 5∼1.0, H/θ=5∼15 and Re
H=5×10
3∼3×10
4 Consequently, the most effective shape parameter for the augmentation of heat transfer was indicated, and a wake flow structure was proposed. And an arrangement of maximum heat transfer coefficient was presented experimentally as a function of shape parameter.
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Koji AKAGAWA, Terushige FUJII, Sigeo TAKAGI, Masaru TAKEDA, Kouich TSU ...
1984 Volume 27 Issue 234 Pages
2795-2802
Published: 1984
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The development of an expander which has high efficiency and uses low-quality vapor-liquid mixture as the working fluid is very important from the view point of effective utilization of water dominated geo-thermal resources and waste heat sources from the factories. The fundamental performance of Hero's turbine, which is a radial outflow reaction turbine, has been investigated experimentally using an air-water two-phase mixture as the working fluid. Small scale models of Hero's turbine, which incorporate a 200mm diameter disk with three nozzles, have been tested in the range of G
l=0.6 to 1.2kg/s and G
g=0 to 12×10
-3kg/s. The effects of air flow rate, water flow rate, and quality on the efficiency and each loss have been discussed. Furthermore, the two-phase flow configuration in the passage of turbine has been observed. '
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Tomio SUZUKI, Ryoichi HIROSE, Kotaro MORIMOTO, Toru ABE
1984 Volume 27 Issue 234 Pages
2803-2810
Published: 1984
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The combustibility of pulverized coal has been studied for the injection of fuel into the blast furnace which is operated under the combustion conditions of the highest temperature and the highest velocity in the steel industry. The combustion efficiency of pulverized coal containing volatile matter ranging from 20% to 40% is from 59% to 93% at the position where the combustion of heavy oil is completed. The combustion efficiency increases with an increasing volatile matter content. Combustibility was determined using ash or titanium as a tracer and by gas analysis methods based on CO
2 production or O
2 consumption. The results indicate that the degree of oxidation coincides with the fraction burned by a titanium tracer method.
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Tomio SUZUKI, Ryoichi HIROSE, Kotaro MORIMOTO, Toru ABE
1984 Volume 27 Issue 234 Pages
2811-2817
Published: 1984
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The combustibility of a COM, a pulverized coal and a heavy oil was studied in high temperature furnaces for the steel making. Combustion efficiency was measured in a furnace with 1 m diameter and 4 m long tunnel, a thermal input of 40×10
4kcal/hr, a furnace temperature of 1300°C and a combustion air temperature of 150-450°C. COM and pulverized coal combustion cause a rapid main reaction and a slow char reaction. The char reaction determines the burn-out point of the fuel. The efficiency of COM containing coal is as high as that of heavy oil. The efficiency of COM containing petroleum coke is lower, because coke combustion produces much char. The efficiency of coal is lower than that of other fuels by 20-50% in the main reaction, and ignition is delayed. An increase of the combustion air temperature and the velocity, and a raising of the fuel injection position promote the main reaction and improve the efficiency.
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Masashi KATSUKI, Yukio MIZUTANI, Byeong-Ryun CHOI, Etsuo SHIBATA, Kats ...
1984 Volume 27 Issue 234 Pages
2818-2825
Published: 1984
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Flames dominated by coherent structures often appear in the shear layer between a couple of parallel streams of hot burnt gas and a cold unburnt mixture. Such flames were investigated by the synchronized Schlieren photography and electrostatic probing technique as well as by the laser Doppler anemometry. The ion current measurements conditioned by the instantaneous Schlieren photography showed that the most violent reaction occurred at the part of a coherent vortex where the unburnt mixture was engulfed. The flame is coupled with microstructures in coherent vortices and has the structure of a 'wrinkled laminar' flame.
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Kenichi ITO, Naoshi MATSUMOTO, Mitsuo KAJI, Masami KOYAMA
1984 Volume 27 Issue 234 Pages
2826-2832
Published: 1984
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Stability of wake flames formed behind a bluff-body with fuel injection was investigated experimentally in various geometries of two-dimensional bluff-bodies such as cylinders with 10-20mm diameters, hemi-circle, 60°wedge and rectangular rods of 12.5mm width. The bluff-body was located in an air stream flowing 5-60m/s. Fuels used were propane, methane, ethylene and butane. Flame stability limits, length or geometry of recirculation zone, distribution of chemical species concentrations, temperature and equivalence ratio in the zone were measured. The results show that the equivalence ratio in the recirculation zone is important in determining the flame limit. The air velocity at blow-off is inversely proportional to the square root of the bluff-body width, and is independent of the direction of fuel injection and the geometry of flame holder except for the rectangular rod.
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Akira NISHI, Teruo SAWADA
1984 Volume 27 Issue 234 Pages
2833-2838
Published: 1984
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To obtain the basic data for assuming the source position of atmospheric diffusion of the jet engine exhaust plume, a full scale field test was done at Chitose Airport for use in the air pollution assessment of the proposed New Kansai Airport. An engine of airbus was examined under a few operating modes. An observation net of about 100 meters wide and 25 meters high was constructed perpendicular to the jet axis, instrumented at several levels with sensord for velocity, temperature and concentration of pollutants. A model test was carried out in the laboratory to get the more widely applicable data and some of the results were compared with those of the field tests. The bending path of the jet axis by a crosswind was determined and a penetration length was estimated from the field test. The decays of maximum velocity and temperature as well as the jet spreads were determined from both field and model tests.
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Hisayoshi SEKIGUCHI, Toshihiko ASAMI
1984 Volume 27 Issue 234 Pages
2839-2846
Published: 1984
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This paper deals with a theory of vibration isolation of a two-degree-of-freedom system subjected to a harmonic motion. The system is made up of two subsystems each having a one degree of freedom. The first subsystem consists of a mass m
1 connected to a foundation in motion through a spring of scale k
1 and a dashpot of damping coefficient c
1 placed in parallel. The second one contains a mass m
2. a spring k
2 and a dashpot c
2, and is attached to the mass m
1 in the same manner. In a special case of c
1=0. the optimum tuning and damping of a dynamic absorber (m
2-k
2 ) have already been studied by Den Hartog et al. However the problem to be studied on the system having two dashpots c
1 and c
2 is still left unsettled. We searched for the optimum suspension of vibration isolation regarding the mass m
1 or m
2 of the system mentioned above.
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Osami MATSUSHITA, Michiaki IDA
1984 Volume 27 Issue 234 Pages
2847-2856
Published: 1984
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In this study, a new method is developed for analysing rotor vibration due to harmonic excitation, in particular, to excitation with frequency multiple of rotational speed, with aim at a computer aided designing for unbalance vibration. vibration due to balls or blades passing. and so on. This new technique, developed by expaning the concept of quasi-modal transformation. is more applicable than the usual modal one. The quasi-modal transformation is characterized by mode synthesis of the following two mode shapes. One is a mode shape obtained by undamped critical speed analysis of rotor shafting restricted at its bearing points. The other is a deflection mode shape caused by forced displacement on the bearing points. Only this new method is effective especially to the analysis of harmonic vibration response of rotor with multi-level shafting. The effectiveness is demonstrated by a 3-disc rotor, and an X-ray tube unitincluding a casing.
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Susumu SATO, Hiroshi MATSUHISA, Nobuaki OHIRA
1984 Volume 27 Issue 234 Pages
2857-2862
Published: 1984
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Vibration and noise of a damped wheel are investigated theoretically and experimentally. A dynamic damper composed of a rubber and a steel thin annular plate is attached to the web of a conventional wheel. In the theoretical analysis, the rubber is assumed to be a spring with viscous damping. The results show that the vibration and noise can be considerably reduced by the dynamic damper. When the fundamental frequency of the dynamic damper becomes equal to the natural frequency of the wheel, the vibration is remarkably decreased. In order to have an effective reduction of the vibration and noise, the rubber should have a large loss factor and the damper should be attached to the outer side of the wheel.
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Katsumi WATANABE, Hiroaki FUNABASHI
1984 Volume 27 Issue 234 Pages
2863-2870
Published: 1984
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In this paper, a simple method of displacement analysis of Stephenson six-link mechanisms of three kinds which have two closed five-link loops including the fixed and driving links is developed in the form of a solution of a sixth order equation. Moreover, their composition loops to arise from inversions of link chains for a set of kinematic constants are discriminated by means of the domains on the angular displacement curve of the component four-link chain; the domains are separated by the points which correspond to the limits of rotation of the driving link of the six -link mechanism and the positions of the longest or shortest distance between the end pairing points of the component two-link chain and are distinguished by the sign of the sine of the relative displacement angle of the latter.
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Katsumi WATANABE, Hiroaki FUNABASHI
1984 Volume 27 Issue 234 Pages
2871-2878
Published: 1984
Released on J-STAGE: February 15, 2008
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This paper deals with the motion-transmission characteristics of Stephenson six-link mechanisms of three kinds which have two closed five-link loops including the fixed and driving links. The positions of mechanisms are analytically determined at which the deviations of displacements of links due to small changes of kinematic constants and the forces acting at pairs due to external forces on links become extremely large. Then, a standardized expression of the functionally variable part of the denominator of the deviations of displacements of links which coincides with the one of the forces acting at pairs is adopted as an index of the motion-transmission characteristics. Moreover, the geometric property of the index is made clear and the relation between the index and the mechanical error in the output is experimantally examined.
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Hiroshi HONDA, Seiichi KITAMURA, Tominori YAMADA
1984 Volume 27 Issue 234 Pages
2879-2888
Published: 1984
Released on J-STAGE: February 15, 2008
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This report presents the results of fatigue testing on torch cut and machined high tensile strength steel (HT80 steel) racks of 40.4mm in module, 25 degrees in pressure angle and 63.5mm in rim thickness. Strain distributions along compressive and tensile fillets of the racks were obtained using the strain gage method and the results wore compared with those obtained using a finite element technique. The relations between the fatigue strength and the strain amplitude at the most critically stressed point in the rack fillet were then obtained utilizing the above mentioned results. Crack propagation behavior in the rack fillets was observed using plastic replicas, a magnifying glass, crack gages and the crack mark method. The results obtained are useful for fracture control of the racks.
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Katsumi YAMAGUCHI, Yasushi KUROSAKI, Minoru MAEDA, Yasushi KODAMA
1984 Volume 27 Issue 234 Pages
2889-2896
Published: 1984
Released on J-STAGE: February 15, 2008
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A new method for sheet metal forming which utilizes the strain-rate dependence of flow stress in the viscoplastic material and the friction-hill phenomenon is proposed. In order to assess its applicability, a dynamic compression test of clay specimens is carried out using a drop hammer apparatus, and the contact pressure on the specimen-platen interface is examined. It is concluded that the proposed method is applicable to sheet forming for relatively small articles. Based on experimental and theoretical considerations, a simple method for estimating the maximum pressure generated under any condition is presented. Some applications of' the process to sheet metal forming are shown.
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