Centrally notched plates were fatigued by changing the notch shape of a hole. And the fatigue crack propagation was investigated. It is revealed that the crack propagation curve has an inflection point; that, after this point, the crack propagation rates are unified by a power function of stress intensity factors; and that the crack length where the propagation curve indicates inflection is identical regardless of the specimen shapes. On the basis of these results, the method of the prediction of fatigue life is explained by the division of the life until this inflection point and, from inflection to failure. The former is estimated from plastic strain at a notch root and the life of smooth specimens; and the latter, from integration of the fatigue crack propagation rate. And a method of the determination of inspection intervals and crack size to be detected in practical use is proposed.

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Thermal recovery and its effects on the stress-strain relations of polycrystalline zinc have been investigated experimentally. Specimens were prestrained in compression at a certain temperature and under several constant strain rates, and annealed isothermally. Results obtained are summarized as follows. (1) During both the static and the dynamic deformations at -195°C, no detectable thermal recovery occurs. (2) At -195°C, the stress-strain relation is able to be determined only by the strain rate at the time within the strain rate range of 10^-4/s to 10^-2 and does not depend upon the strain rate history. (3) The activation energy obtained for thermal recovery is about (10∼12)kcal/mol and this value corresponds to the migration energy of vacancies produced during the plastic deformation.

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In studies of moving load problems, Galilean or Laplacian transformations have been commonly used by several previous investigators to construct the solutions. Meanwhile in this paper analytical techniques of superposition of harmonic vibrations are available because the elements composing an elastic half space are excited periodically by reciprocating surface loads. Formal solutions of the equation of motion described in terms of well known displacement potentials φ and ψ in the theory of elastodynamics, are decided from the theory of partial differential equations. Numerical calculations are carried out and we find out the differences between both stress distributions produced in the interior of the media by surface loads moving forward and by the Loads moving backward, even if both the loads coincide instantly with each other. That is one of the properties of the response of an infinite extended solid to reciprocating loads. These differences become large as the moving speed increases.

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This paper deals with the vibration and the transient response problems of a viscoelastic continuous beam on non-periodic elastic supports. In the analysis, the restoring forces of the elastic supports are regarded as unknown external forces applied to the beam. The solution for the viscoelastic beam is obtained from the correspondence principle by applying the Laplace transform to the constitutive equation and the equation of motion for the elastic beam in terms of these unknown forces.

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At the R.P.E. transition temperature, named by one of the authors, it was found that the stress-birefringence relation of polyester was linear even in inelastic range (in elastic range as well). By using this relation, factors of stress concentration and stress distributions at a free boundary were determined, and two-dimensional stress distributions at points apart from the free boundary were calculated by employment of the shear-difference method. Results obtained were in substantial agreement with the experimental results reported by M.M.Frocht. Moreover, the stress-strain relation of polyester at the R.P.E. transition temperature showed a good approximation to that of metal prototype, especially Al-alloy. Thus, it was proved that the photoplasticity utilizing the stress-optic law of polyester at the R.P.E. transition temperature is available to analyze the stress distributions in certain metals and polymeric materials.

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About a rotor accelerated across a resonance, which possesses a linear oscillating system with a single degree of freedom, excited by an unbalanced rotating mass, it is said that by investigating the non-stationary transitions of motion of the rotor under the critical condition that the rotor can pass barely through resonance or not, it is possible to formulate the condition; and an estimating expression for passage through resonance is introduced as follows; K=πμ_Iμ_Mqρmax < 1.0 In this case, if the rotor has a circular oscillating system moving in a plane, the estimating expression is given as K=2πμ_Iμ_Mqρmax < 1.0 where ρ_max is estimated by E_q. (9). Furthermore, about a rotor having an uncoupled oscillating system with two Furthermore, about a rotor having an uncoupled oscillating system with two degrees of freedom, 2 kinds of estimating expressions are proposed, which are divided into 2 parts depending on the frequency difference between 2 resonances.

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In order to attain dynamically optimum design of machine tools which would have minimum chance of machining chatter, an approach based on energy balances of a mathematical system at the resonance is developed and analysed theoretically. This method aims that the maximum compliance of the tool-work relative displacement in the direction normal to cut surface caused by the cutting force at the cutting point must be minimum across all frequency ranges. Using the computer simulations of machine tool structures, modal flexibilities are computed, by the magnitude of which the chance of regenerative chatter is judged. Focusing on the particular mode where the modal flexibility is predominantly high, and by consulting with the energy distribution through the complete structure at the mode, a design change is proposed such that the static flexibility is small and evenly shared by modal flexibilities in many modes. The outline of a computer program is described and demonstrated by computed and experimental results on a practical machine structure.

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The viscous flow around a flat plate making small unsteady motion in a uniform flow is analized on the basis of Oseen's equation. The exact elementary solutions of the basic equations in the cases that concentrated force acts at the origin parallel and perpendicular to the uniform flow are presented at first. These solutions yield the fundamental structure of each case. The solutions are applied to the problems of plunging motion of a flat plate and of oscillation parallel to itself. Substantial understanding was obtained from the interpretation of the calculated results concerning the effects of viscosity of the fluid on the unsteady forces of a flat plate.

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In this paper, suction performances of bent axis type and swash plate type axial piston pumps are investigated experimentally. At the same time, the relationship between the pressure in the cylinder and the bubble formation is observed using a simulated model of piston pump whose cylinder is made of transparent plastic. The experimental results about critical suction performances of axial piston pumps are compared with the evaluated results obtained in the 1st report. And it becomes clear that the agreement of both results is fairly good.

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In succession to the previous study, radiative heat transfer in three-row and four-row gray cylinder systems with square-center arrangements is exactly analyzed to discuss the influence of the number of rows on the characteristics of heat transfer of these systems. Radiative heat transfer in semi-infinite rows of gray cylinders as a limiting case of a large number of rows is also analyzed approximately by using a simplified model, and the accuracy of the solutions is evaluated. On the basis of equivalent emissivity, the characteristics of cylinder-row systems are examined in relation to the number of rows, surface esmissivity and center-to-center distance of cylinders.

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A statistical method is proposed to express the gas-liquid interface on a lot of waves existing in the ripple regimen of upward two-phase annular flow. Experiments were made to establish the present method on local liquid holdup and probability density of wave to its height. It was found that the probability density of wave conforms to log-normal distribution and the crest of wave becomes sharp as flow regime shifts from ripple to disturbance wave.

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To improve the performance of a gas turbine, the authors investigated the suction air cooling gas turbine cycle with a vapor compression refrigerator, where the refrigerator driven directly with a part of turbine output cools the suction air to reduce the required power of the air compressor. Based on the thermodynamic characteristics of this combination cycle, the authors are fully convinced that it is possible to improve the thermal efficiency and specific power in addition to suppress the variation of the performance due to a change in atmospheric temperature.

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To examine the influence of the pressure wave in an intake pipe system on the fuel flow quantity of a crankcase compressed two-stroke cycle gasoline engine, the authors carried out some experiments and then analyzed numerically on the unsteady characteristics of a simplified carburettor. Some conclusions reached are summarized as follows. (a) The fuel flow quantity from a carburettor decreases in inverse proportion to the amplitude of the pulsation wave acting on the carburettor throat and that is governed by the matching condition q^*=15·a/N(L_S+Δl). (b) When the throttle valve of carburettor is a small opening, the fuel flow quantity increases with the engine speed and the length of the main fuel pipe system because of the inertia effect of fuel liquid column in the main fuel pipe. (c) To prevent the variation of excess air ratio with the engine speed, the utilization of a Helmholtz resonator with elastic wall is effective.

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In order to study the cycle-by-cycle variations of combustion in a diesel engine, a continuous data acquisition system utilizing the analog computing circuits was developed and its accuracy was verified satisfactorily. Preliminary experiment proved that the amount of injected fuel per cycle could be measured indirectly by the integrated value of the injection nozzle lift. Then, applying the whole system to a two-stroke diesel engine, the necessary data including the indicated mean effective pressure etc. were collected and analyzed statistically. The result indicates that the irregularity of amount of injected fuel per cycle, which is subjected to the varying characteristics of the injection system concerned, mainly governs the variation of the indicated mean effective pressure.

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An analytical method of differentiating the link vectors in the single-loop kinematic linkage with respect to its design parameters is presented. In that the first derivative of a unit vector is perpendicular to the original one, this method is analogous to one of determining the velocity vector and the acceleration vector of link in the closed-loop kinematic chain. General expressions of the first and second derivative vectors are derived for the link vectors both in the open-loop kinematic model of the articulated robot arm and in the closed-loop 4-bar linkages.

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Analysis of transmission error curve of a pair of gears measured by a single flank meshing tester shows that the error can be separated into harmonic components and random ones. In this paper the effect of the random components of the error on dynamic loads is analysed theoretically and one example of numerical result is shown. Dynamic behavior of gear systems is considered as nonlinear, nonstationary random process because of variable spring constant, backlash term and random component of error, so the Fokker-Planck equation is derived. It is analysed approximately using statistical linearization and the mean and the variance of dynamic loads are calculated numerically. Monte-Carlo-Simulation is also performed to find dynamic loads by means of an analogue computer. The results show that the mean of the dynamic loads remains at similar level as in deterministic process where the random components of error are not considered for any gear speed, but the variance of them increases rapidly with an increase in speed over resonance frequency.

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In order to get the fundamental data about the extrusion method in the coexisting state of liquid and solid in Al-4Cu alloys with magnesium, the influences of extruding pressure, billet temperature and magnesium content on the mechanical properties of the extruded product have been investigated. The tensile strength of the extruded product fluctuates with the billet temperature. As the temperature falls, in other words, as the solid component increases, the tensile strength at first increases and after reaching a maximum, it begins to decrease and thereafter it begins to increase again. The microstructure of the extruded product consists of two different grains. One of them is the same which existed during extrusion and the other one is the grain that appears during cooling.

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