The fiber reinforced composites have come of age as economically and structurally available materials. It is well known that these have some basic features different from iron materials, such as a considerable scatter of mechanical properties and pronounced rigidity reduction under repeated stress. It this work, in order to investigate these characteristic fatigue behaviors, the number of cycles to failure, the reduction of rigidity and the residual strength are examined in three kinds of the commercial fiber reinforced composites under pulsating tensile stress. The fatigue damage in the proposed unit model having the properties peculiar to composite laminate is computed by using the linear elastic fracture mechanics and the calculated results agree with the experimental data fairly well.

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In this paper, a technique to determine effectively an optimum shape of two-dimensional and axisymmetric bodies under body force is proposed. This technique is based on the iteration of a sequential search method consisting of the following steps. In the first step, the superiority or inferiority of a given shape, which satisfies the constrained conditions of design, is judged by the deviation from the design object stress value. In the second step, this given shape is modified to an optimum shape by the proportional transformation method of the finite elements, which is considered an effect of body force. By using this technique the optimum shapes of the basic problems under gravity load or centrifugal force are obtained and the results are compared with the corresponding shapes given by elementary theory. Moreover and optimum shape of the rotating disk with a rim and a bored hole is obtained by applying the optimization technique. The validity of this shape is examined experimentally by comparing with the fracture strength of a bored, uniform thickness disk.

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This paper contains a solution in series form for the stress distribution in an infinite elastic solid which posseses three spherical cavities. The loading consists of a uniform field of uniaxial tension at infinity in the direction perpendicular to the common axis of the cavities. The solution is based upon the Papcovich-Neuber stress function approach and deduced with use of the spherical harmonics. The method can be developed for a variety of cavity numbers and sizes. Numerical evaluations are given for the stress distributions in the infinite medium containing (i) three equidiameter spherical cavities or (ii) two outer cavities of the same size and the central cavity of any size. The results illustrate the interference of three sources of stress concentration in a three-dimensional problem.

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A certain amount of slip occurs between the adjacent grains in the flowable zone of a dry granular system. In this case the distribution of forces around grains is considered to be modified from an ellipsoid similar to the stress ellipsoid. The expressions of stresses in this zone are derived from this idea, and the force distribution around grains is revealed. The domain in which slip occurs on the surface of the model sphere which represents a grain is made clear, and the approximated formulae for the relations between the stresses and the principal values of the forces around grains are derived. Furthermore it is found that the macroscopic internal friction coefficient of a granular system may differ from the friction coefficient between the surfaces of the adjacent grains in it.

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The transient vibration of a shaft passing through its several critical speeds at a uniform acceleration rate was investigated. The shaft is assumed to have a uniform section and be supported at both ends by springs and dampers. First, the free vibration of the system was analyzed to get the relationship between the damping given at the ends of the shaft and the modal damping ratio. Next, after evaluating the modal eccentricities and the modal damping ratios of the system, we calculated the maximum amplitudes of the shaft passing through the first and the second critical speeds at various acceleration rates using the approximate equations, which has been obtained from the analysis of the transient vibration of a system with one degree of freedom. Further, these calculated results were compared with the experimental ones.

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When a rotating shaft is supported by single-row deep groove ball bearings, the restoring force of the shaft has nonlinear spring characteristics. In the case of an unsymmetrical shaft, the subharmonic oscillation of order 1/2 of the forward precession shows unique features owing to the influence of some of the nonlinear components which have no effects on such an oscillation of a symmetrical shaft. By changing the assembly of the experimental apparatus and the degree of unbalance, we could obtain three kinds of resonance curves concerning this subharmonic oscillation. They are the following: a stable resonance curve of the hard spring type, an unstable region where unstable vibration with frequency 1/2·ω(ω: angular velocity of the shaft) appears, and the case where no subharmonic oscillation appears. In the analysis of such an unsymmetrical shaft system with nonlinear characteristics, the method utilizing normal coordinates cannot be used. We can explain such phenomena theoretically by the method proposed in this paper.

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The stability characteristics of spherical spiral groove bearings lubricated with incompressible liquid are investigated theoretically. Solving a differential equation for a bearing which have an infinite number of grooves, we obtain the pressure distribution induced by small vibrations of a rigid rotor about a static equilibrium position. From the pressure distribution we derive a stability criterion for radially unloaded bearings, and clarify the dependence of the stability on bearing parameters and on axial displacements of a rotor. The bearing parameters considered are the spiral groove angle α, the relative groove depth H_g, the groove ratio δ, and rotational speeds of grooved member ω₁ and smoothed member w₂.

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Ordinary Lagrange function and penalty function methods are typical methods for solving nonlinear programing problems with constraints. The application of the ordinary Lagrange function method is in general limited to convex programing problems. The penalty function method can be applied to nonconvex programing problems, but may suffer from numerical difficulties. The penalty shifting method is superior to the above two methods, since it can be applied to nonconvex programing problems without suffering from numerical difficulties. In this paper two geometric interpretations for the penalty shifting method are mainly given, so that its characteristics may be more clarified. First, the correction rules of two parameters and the relation between one of the parameters and the existence of a saddle point are investigated by the ordinary geometric interpretation. Secondly, the operation of the parameters is also investigated by a new geometric interpretation, and finally, the result for a nonconvex programing problem is illustrated by two geometric interpretations.

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This paper describes an underwater imaging system using multi-frequency ultrasonic holography. This imaging system has 11X11 receiving array and reconstructs the image by holographic calculation. In conventional mono-frequency holographic system, undesirable ultrasonic refrection from non-target objects degrades the quality of image. To prevent this image degradation, the authors propose a method of multi-frequency ultrasonic holography. It prevents image degradation not by an increase in the number of receivers but by an increase in the number of holograms formed by different ultrasounds. A good quality image can be obtained from a synthesized hologram that is vector summation of the phase-corrected holograms. The reduction rate of undesirable ultrasound is estimated to be 1/√(M), where M is the number of diffent frequency ultrasounds. The upper and the lower limits of applicable frequency bandwidth are presented. Finally the prevention of image degradation is demonstrated by experiments in the water.

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To shorten the time consumed for design computations in many engineering branches, the authors intend to use a new type computer system called array computer, which has hundreds of arithmetic units (AUs) connected in a multi-dimensional network. The most important, but difficult problem in design of this array computer is the development of an effective system of parallel data transmission between AUs. Hence this report deals with the development of this system, comparing the data transmission efficiencies of many conceivable systems. The results show that the effective arrangement of AUs is, (1) four- or five-dimensional array in the case of 1024 AUs, and (2) four- or six-dimensional array in the case of 4096 AUs. In both cases each AU is connected directly via data transmission lines with all AUs which lie on all coordinate axes passing through itself.

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In laminar flow of suspensions through a circular tube, particles migrate into a concentric annular region with the radius about 0.6 of the tube radius. This phenomenon is well-known as the tubular pinch effect. To clarify the mechanism, the influences of relative particle-fluid velocity, Reynolds number and particle diameter on radial particle displacement (lateral migration) were investigated by measuring the motion of a suspended spherical particle in laminar flow through a circular tube. Consequently, it was found that the motions of particles could be classified by the particle Reynolds number. And, especially, the relation between the particle Reynolds number and the equilibrium radial position of particles and the existence of critical particle Reynolds number for shifting from unilateral migration to bilateral migration were clarified.

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The revolution characteristic of feed rate of a rotary feeder is examined theoretically and experimentally when back pressure is not applied to the feeder outlet. The revolution giving the maximum feed rate is dependent on the inlet dimension, the total volume of wheel rooms and the number of wheel rooms of the feeder and on the relaxation time of solid particle. For solids having large relaxation time the maximum feed rate becomes independent of the relaxation time. Discrepancy between experimental results and a theory is largely due to irregular outflow of solids from a hopper to the feeder inlets.

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By using a crossed cylinder friction machine, the rolling-sliding friction tests under a lubricating condition were carried out, and the scoring marks which had been induced by single friction were studied. Then the initial situation of scoring can be decided by using a drawing method from the scoring marks on upper and lower cylindrical specimens. The features of scoring marks on the normalized steel, the hardened and tempered steel and the surface-hardened steel were also clarified by the observation with a microscope. And then the surface flash temperature at the initial situation of scoring was investigated on the basis of calculating results of frictional surface temperature in the elliptical contact area.

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The scoring resistance of the Vau-Null gear pair whose centre distance is not changed by the variation of the amount of addendum modification was examined from the point of view of the critical surface temperature rise on the meshing faces of the gears, and the following correlations between scoring resistance and the amount of the addendum modification of the gears were clarified : (1) The position of the maximum surface temperature on the meshing faces of the Vau-Null gears is remarkable affected by the number of teeth of pinion, gear ratio, the coefficient of addendum modification of gears and module. (2) The effect of the coefficient of addendum modification on the surface temperature on the meshing faces is complicated, and the optimum value of the coefficient of addendum modification against the scoring resistance of gears is decided by gear ratio.

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The limiting load for scoring was investigated by means of the FZG gear testing machine. The influences of coefficient of oil viscosity and concentration of anti-wear agent (Zn-P type) in oil upon the limiting load for scoring were disclosed. Furthermore the results of these gear tests were compared with the results of 4 ball tests. We have found in general that the higher the revolutional speed of gear, the greater the the influence of anti-wear agent upon the increasing rate of limiting load for scoring. And further we have found that the lower the viscosity of base oil, the greater the influence of anti-wear agent (Zn-P type) up-on the increasing rate of limiting load for scoring.

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In order to detcrmine the strength of induction-hardened chromium-molybdenum steel spur gears, fatigue tests were performed using a power circulating gear testing machine. As the result, the surface durability was obtained in connection with dynamic loads and it was shown by microscopic observation that there occurred fatigue tooth breakages starting from the middle tooth height which are induced by the spallings on tooth surface or sometimes bending fatigue fractures at the tooth roots depending on the dimension of tooth width. Moreover, it was made clear that tooth surface strength of induction-hardened gears must be evaluated in terms of stresses beneath the surface.

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This paper presents one of the methods for deriving a turbulent lubrication equation and a solution for the equation. The turbulent lubrication equation in the study is developed by such a procedure that the wall shear stresses in pressure flows and shear flows are evaluated based on the friction law of fluid, and their stresses are applied to turbulent lubrication by introducing a concept of equivalent pressure flow. From the analytical solutions, the effects of pressure flows on turbulent lubrication which have been neglected hitherto are considered. The effects are remarkable in the superlaminar flow regime in transit from laminar to full turbulent flows.

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In this paper, an application of the turbulent lubrication theory developed in the first paper to the finite width journal bearings is presented. Bearing performances such as film pressure, load capacity, frictional force and rate of flow in turbulent flows are evaluated by the numerical analysis. The effects of pressure flows on the performances not previously encountered are considered from the analytical results, and are discussed comparing with the published papers. Also, an experiment in a range of high eccentricities and of the mean Reynolds numbers up to 5000 is conducted to compare with the theoretical results. From agreement of the experimental results with the analytical ones, the validity of the theory is confirmed.

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The surface properties of workpieces obtained by skiving process (off-center turning) have been investigated experimentally for the effect of cutting conditions. The fidelity of transcription of cutting edge profile to skived surface and the methods to improve the surface accuracy are discussed. It was found that the surface roughness profile appeared having a plateau shape with small value of centerline depth Rp and that the surface roughness could be reduced by using the skiving tool with a small negative clearance angle or a certain edge roundness. The latter result can be explained in terms of the stronger burnish action. It is concluded that, from the viewpoint of the fidelity of transcription by power spectra, cemented carbide and cermet tools are superior to high speed steel tool.

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The plastic deformation of circular membranes of a strain-rate dependent, work-hardening metal is analyzed based on the strain increment theory. Numerical solutions for aluminum membranes are obtained under various types of loading as well as impulsive pressure pulses caused by underwater wire explosions. When the duration of a loading pulse is less than one-third of the time required to finish the deformation of the membrane, the deflection of a deformed membrane depends almost only on the impulse of the loading pulse and the instantaneous profile of the membrane is found to be trapezoidal during deformation. The relation between impulse of loading and deflection is calculated and illustrated. The forming limit due to peripheral necking is discussed. The neglect of strain-rate dependency of material leads to a notable underestimation of the forming limit.

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