Influences of stress ratios and stress cycle frequencies on cyclic stress corrosion crack growth characteristics of a high-strength steel have been investigated. The influences of stress ratios on crack growth rate under cyclic SCC are clearly distinguished between above and below K_ISCC. In the range of K_max, K_FSCC≤ K_max < K_ISCC, a decrease of R causes not only an increase of da/dt but also a lowering of K_FSCC. In this region crack growth rate is cycle-dependent, and the crack growth by a cyclic SCC is dominant. In high K_max, K_max≥ K_ISCC, time-dependent da/dt increases with an increase of R and the crack growth by a static SCC is dominant.

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Torsional fatigue strength of several types of shrink fitted shaft couplings is estimated based on the results of stress analysis, in which the changes of frictional coefficient and contact pressure during cyclic loading are taken into account. Then these estimated strengths are confirmed by torsional fatigue tests. The results are summarized as follows. The firictional coefficient in the slip region increases steadily with an increase of cycles and saturates for more than 10⁴ cycles. The saturated value of it is about 0.7. Torsional fatigue strength reduction factor of shrink fitted shaft is found to be K_f=1.28, which is far smaller than the rotational bending fatigue strength reduction factor (K_f=2∼3). Anti-fretting measures such as groove, taper are found to be not so effective for torsionalfatigue as for rotational bending fatigue.

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By applying a slip -initiation phenomenon by fatigue in an iron foil attached to a specimen, the method of obtaining cyclic stresses acting upon the specimen at high temperatures is studied basically. Effects of elastic moduli of basic materials, speeds of cyclic loads and test temperatures on the critical stress of slip-initiation in the iron foil are examined. The critical stress of slip-initiation is dominated by cyclic shearing strain on the surface of basic material and becomes lower with a decrease of cyclic speed. As an application of the method, stress-concentration factors in notched specimens are obtained under various cyclic speeds and temperatures. The results are in good agreement with those obtained previously. It is concluded that the present method can be applied favourably for stress measurement at high temperatures up to 430°C.

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Stress-strain relation of brass for the plastic deformation along bi-linear strain trajectories with various corner angles are expressed in a form of vector equation satisfying Ilyushin's special postulate of isotropy, with the use of Valanis' intrinsic time scale. A matrix of influence function is introduced for expressing clearly the history effects between the deformations before and after the corner point, and especially the coupling functions in the matrix are estimated according to experimental results. The stress-strain relations herein obtained are found to approximate with high accuracy the variations of stress components accompanying the increase of strain intensity after the corner of strain trajectory.

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The instability problem stated in the title is analyzed on the basis of Biot's mechanics of incremental deformations. The strip is reinforced by inextensible fibers in the direction of its width. In the course of the analysis, the matrix of the reinforced strip was specified as the socalled Blatz-Ko rubber, solid or foam. It was found that the strip of solid rubber never buckled under tension, while the one of foam rubber became unstable even under tension. There exist two types of buckling for the foam rubber : shear and internal buckling. However, the latter does not manifest itself physically, since the former always occurs first. The whole buckling aspect of the strip is similar to that of a slab in the plane-strain state.

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Up to the present, two flow models for pseudo-shock waves have been presented, i.e. shockless model and diffusion model. However, since the effects of upstream boundary layer and wall friction in the pseudo-shock region are not considered in these models, the flow properties calculated by these models are identical with those by the theory of normal shock wave, and they are much different form experimental values. In the present study experiments have been performed to investigate the effects of the upstream boundary layer on the pseudo-shock waves, by varying the Mach number and boundary layer thickness upstream of the pseudo-shock. Based on the results and modifying the diffusion model, a new flow model of the pseudo-shock has been presented in which both effects of the upstream boundary layer and the wall friction are taken into account. Calculated values by this modified diffusion model agree better with the experimental values than the previous flow models.

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This study is concerned with the flow of a viscous incompressible fluid between eccentric cylinders which rotate with respective angular velocities. The flow pattern between cylinders, and the torque and flow force exerted on each cylinder are discussed for a wide range of radius ratios and eccentricities. The revolutionary motion of the rotating inner cylinder around the center of the stationary outer cylinder is also discussed. The analysis is based both on the Stokes approximation and on the numerical solution of the Navier-Stokes equations. The flow patterns obtained from the analysis are compared with experimental results.

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The compressibility effects on bubbly water flows in comparison with those on compressible pure water flows past a steady two-dimensional supercavitating wedge are clarified by a local linearization technique which preserves the local features of the flow field with unified approach and higher accuracy than the former linearized one. The range of freestream Mach numbers is clearly defined for the subsonic, transonic and supersonic bubbly water flows. The clarifications of pressure waves in supersonic bubbly water flows are given. In purely subsonic flows the cavity drag is shown to be smaller while the cavity length is larger than that in compressible pure water. In transonic and purely low supersonic flows both cavity drag and length are shown to be less than those in compressible pure water and depend substantially on the air contents.

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Free convection heat transfer near the leading edge of an isothermal semi-infinite vertical flat plate with finite thickness has been analyzed numerically by the finite difference method for Pr=0.72, The effects of the adiabatic horizontal floor under the leading edge and of the shape of the leading edge on free convection heat transfer have been made clear. When the dimensionless height, H, of the leading edge from the floor is larger than 40, Nusselt number distributions near the leading edge are hardly influenced by the floor, taking lower values than any previous perturbation solutions and being correlated by the following equation : Nux/X^3/4=0.356 8+0.120 9 X^-1.238 X≥1.5 The Nusselt numbers near the leading edge of flat plates with finite thickness are correlated by the Grashof number based on the plate thickness, and the present results for a triangular leading edge agreed well with previous experimental results.

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A method for the measurement of the thermal diffusivity of a flat plate specimen is presented. In contrast with other traditional methods, the method permits the measurement to be conducted under arbitrary boundary conditions; namely, arbitrary heating and radiating conditions. The method utilizes a general solution of the Laplace transformed heat conduction equation and the Laplace integrals of temperature responses detected at three different positions in the specimen. The numerical tests are carried out to confirm the nature of the method, to verify the method and to evaluate the measuring errors. The Laplace parameter s is shown freely determinable when the product of s by the measuring time t_max satisfies the following relation : 8 ≤ st_max≤ 12. The measured thermal diffusivities of polymethylmethacrylate and soda glass are shown to be in good agreement with the reference data.

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An experimental investigation was made on the pumping characteristics of an air lift system consisting of an air-water separator and a constant head tank which are connected by a 25.9 mm I.D. U-tube and a water-return tube. This type of natural circulation system presents a signifacant fluctuation of flow; especially in some flow conditions with reduced pressure, there occurs a self-excited flow oscillation. This is attributed to the compressibility of gas in a gas-liquid two-phase mixture and reversion of water flow from the two-phase mixing section to the head tank. Time-averaged flow rate of water increases with the intensity of flow oscillation. The gas flow rate corresponding to the initiation of lifting water is reduced due to the flow oscillation.

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The present paper treats the heterogeneous type of spray combustion and aims to analyse the field of combustion around a droplet in the spray and then estimate the effective diffusivity by considering the many-body effect. The cell model method is applied to overcome the mathematical difficulty of many-body interaction and the variational method is utilized to introduce an approximate diffusion equation in the case where there is a macroscopic flow of mass. The deformation of the flame sheet surrounding a particle is also calculated.

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A bearingless windmill-type gas flowmeter was developed, and its characteristice are described with both theoretical explanation and experimental results. The windmill is mounted on a float, and the float is on liquid in a cup so that the friction against the rotation of the windmill due to friction of the float to liquid is reduced to be negligible at slow rotating speeds. To keep the axie of rotation of the windmill assembly to the center, a magnetic attraction is introduced. The flowmeter shows a satisfactorily linear relationship between rotating speed and flow rate over a wide range from 15 to 500 l/min.

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Homogeneous thermal oxidation of ethane-oxygen mixtures, highly diluted with argon, was studied in shock waves by the following emission and absorption of various species in the course of their reaction. The equivalence ratio φ= 3.5 [C₂H₆]/[O₂] was varied from O.2 to 2.0. The total density extended from 10^-5 to 10^-4 mol/cm³, corresponding to 0.1 to 1.0 MPa (1 to 10 atm) at 1400 K. For highly diluted mixtures the experiments indicate an influence of argon density on the induction period. In order to obtain the mechanism of the oxidation of ethane-oxygen mixtures, molecule and fadical profiles were calculated by the numerical integration of 58 reactions and compared with the experimental results. The calculated results agreed well with those experimentally determined. From this comparison a reaction schema from ethane oxidation was proposed.

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Recently, a turbine blade is becoming wider, thicker and longer, therefore it is not enough to know the vibration characteristics of only a single tirbine blade. In the present paper, the vibration characteristics of bladed disk assemblies of axial-flow turbines are experimentally investigated and calctlated. The natural frequencies and the natural modes of bladed disk assemblies are detected experimentally using the fast Fourier transformation of the measured impulsive force and the acceleration, and they are calculated by a new cyclic symmetry method the authors developed. The results of the calculation are in good agreement with those of the experiment, and it becomes clear that this new cyblic symmetry method is effective for analysis of periodically symmetric structures.

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In this paper, a seismic response analysis method of a hexagonal column group installed in a liquid with narrow clearance between columns, which can be supposed to make a coupled vibration due to the interaction between the columns and the liquid, is shown under the condition of continuity in the flow passage and the velocity potential theory. As a result of the parametric study on the sizes of a column group, their vibrational characteristics become clear, and it is possible to estimate the seismic response characteristics of the column group in a liquid for a great number of columns. Moreover, some of calculated values are compared with experimental ones, and it is found that they coincide closely with each other.

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During the start-up of synchronous motor driven systems, resonant torsional vibration can be caused by the pulsating torque of the motor. In this paper, a method of nonlinear transient analysis for this problem, using a digital computer, is proposed which can treat the effect of backlash. And, with this method, computation time can be saved. The calculated results of this method are in good agreement with the experimental data and the field test data. The vibration phenomena of such systems are examined thoroughly, and some different aspects between the response of nonlinear systems which include backlash and that of linear systems are shown.

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In order to improve the isolation performance of conventional vibration isolators, this paper proposes an application of dual dynamic dampers in place of viscous damping elements in the vibration isolator. The dual dynamic dampers equivalent in total size to a single one can be applied in a limited space. To reduce effectively the transmissibility at resonance peak, the optimum adjustment condition of the dual dynamic dampers is investigated theoretically and the design data of them are presented in graphical form. Subsequently, the effect of the dual dynamic dampers to control the resonance peak is shown to be greater than that of a single dynamic damper. The effectiveness of the vibration isolator equipped with the dual dynamic dampers indicated by the theoretical analysis is demonstrated experimentally by using a compact variable-stiffness type dynamic damper with magnetic damping.

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This paper is a study of the switching time in a bistable wall attachment fluid amplifier. We have made a bistable wall attachment fluid amplifier with a freely movable control nozzle and experimented on the switching time using this fluid amplifier. Being based on Sher's method, we have devised a similar model with the control nozzle angle γ as a new parameter. The calculated values from this model agreed well with the experimental results. When the inflow rate from the control port is same, the smaller the control nozzle angle is, the shofter the switching time is. Finally, we have found that the optimum control nozzle angle exists within some region (for instance, the region from -15 degrees to -25 degrees).

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The purpose of this paper is to examine a distribution of contact pressures on the interface of a cylindrical clamped part fastened with a tap bolt to a base which is sufficiently larger than the clamped part. The analysis is treated as a contact problem of two bodies. In order to obtain the distribution of contact pressures, the iteration method is used by the three dimensional theory of elasticity. Experiments are carried out and the analytical results show a fairly good agreement with experimental ones. In addition, the force ratio, which is the ratio of an increment of bolt axial force to a load when the load is applied on a bolted joint, is analysed. Corresponding to this analysis, an experiment is carried out, and the analytical result shows a fairly good agreement with experimental one.

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Theoretical analysis is presented for the dynamic behavior of a wave energy converter which has oscillating two-dimensional cylinders and absorbs power in an incident sinusoidal wave train. The energy converter is an array of two or more than two bodies connected by rigid links. By taking into consideration of the interactions of waves between the floating bodies, dynamic equations of a floating system with inertial, restoring and damping forces are derived using velocity potentials assuming a linear theory. Rate of energy absorption when each body in the array oscillates in two modes is obtained. It is shown that nearly 100% efficiency is available under the approximate tuning condition when three or four oscillating bodies are used and also that the band width of energy absorption efficiency will be largely widened compared with the conventional single body energy converter. These characteristics are of great practical value seeing the changeable nature of ocean waves.

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One of the causes of the thermal deformation of a machinetool-workpiece system is the heat of chips piled on it. The amount of the thermal deformation due to this cause, however, is hardly yet known. Because, the values of thermal conductivity of accumulating chips and thermal contact resistance between accumulating chips and the surface of the system are hardly clarified. In this paper, the thermal properties mentioned above have been experimentally investigated by using accumulating chips made of different kinds of material and under different cutting conditions and moreover a theoretical investigation has also been carried out considering a model of accumulating ideal chips. From above results, it has been made clear that the value of the thermal conductivity of accumulating chips can be estimated by using the values of the thermal conductivity of the material, the void ratio and the number of chips per unit volume and that the value of thermal contact resistance can be approximately estimated by using the same factors mentioned above.

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