The present paper gives a theoretical solution for an infinite plate containing a pair of circular holes, which are filled with elastic inclusions of another material, and subjected to uniform tension in the direction of the x- and y-axes. The analysis is developed on the basis of the Airy's stress function in the generalized plane stress and by applying the bipolar coordinates. A method of perturbation is adopted for the determination of unknown coefficients in the solution. The maximum stresses on the common boundaries are calculated and compared with the results available.

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Low cycle fatigue fracture surfaces of an aluminum alloy (17S-T4) and a low carbon steel were studied fractographically to throw some light on the transition of the fracture surface topography form the static type characterized by dimples to the fatigue type characterized by striations. The mechanism of formation of the tire tracks was also studied in detail by mean s of stereographic technique, matching technique and panoramic pictures taken by scanning electron microscope, and it is concluded that the tire tracks are impressions made by protrusions or edges on the mating fracture surface each time repeated stress was applied. Some examinations were also made on the mechanism of formation of the striations and the results suggested the validity of the model proposed by Laird and Smith. Finally, measurements were made of the striation spacing with notched specimens of aluminum alloy, and the results were summarized fairly successfully in terms of stress intensity factor calculated by taking account of the stress concentration due to notch effect.

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The coefficient of kinetic friction between sliding solids is influenced by vibration. This paper treats such a case as a solid body sliding on a surface vibrated sinusoidally in an arbitrary direction. Defining the effective frictional force effective to the motion of a solid body equivalently as a mean value of components of the kinetic frictional force projected in the slide direction, the effective coefficient of kinetic friction is expressed as a function of the velocity ratio V, the velocity of solid body X^^· to the amplitude of vibration velocity Aωsinγ. Some results obtained thus, analytically and also experimentally, are as follows : the effective coefficient of kinetic friction generally reduces at least with a decrease of V by any vibration, though varied in modes. And simultaneously the Coulomb friction comes to behave just like a viscous one. The most effectual direction of vibration to reduce it, is coincidence with that parallel to sliding, that V is near unity.

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Analysis is performed on the unsteady flow of liquid in a long circular tube in which the effects of tube ends are negligible. The analysis is made considering radial flow components and pressure distributions on the cross sections of the tube. Calculated transfer matrix which dominates velocity and pressure variation agrees well with experimental results under sinusoidal inputs. The proof is given that the pressure distributions on the cross sections are negligible. The viscosity of liquid affects the velocity distribution function. Numerical difference between exact transfer matrix and approximated transfer matrix which is calculated assuming Poiseulle flow, increases for higher frequencies especially in the neighbourhood of the characteristic frequencies of the pipeline.

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The frequency of a sound wave is changed from the original one by passing through the rapidly temperature changing gas. The new technique for measuring the varying gas temperature by detecting the frequency change of the passing ultrasonic wave was applied to the temperature measurement of combustion gas in a four cycle reciprocating engine. For the check of the measured temperature using this new technique, the measured sound velocity was compared with that by the conventional direct sound velocity measuring method. As a result of the experiment, it was concluded that the new measuring technique was reliable.

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In earlier syntheses of path generating link mechanisms attention has been paid only to make a coupler curve pass through the precision points on the ideal curve, and the order of them has been neglected, which is an important problem in tracing the ideal curve. In the present paper, the authors first classify, about the number of loops, the curves described by a point on the coupler link jointed to the driving link and obtain a planer five-link mechanism. Synthesizing a four-link mechanism which satisfies the angular relation between the driving and driven links of the mechanism, and combining these five and four-link mechanisms we obtain a six-link mechanism. Modifying the link parameters so that the tangential error of the coupler curve may become small, we can synthesize a planar six-link mechanism satisfying the order of the precision points on the ideal curve. The concept presented in the paper is applicable to multiple-link mechanisms.

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Conditions governing the roughening phenomenon of free surface in deformation processes are investigated. It is shown that the surface roughness increases with strain, and the roughening rate is affected by the mode of deformation (tension and compression), and by the position of the surface. The effects of the deformation mode and the position of the surface are related with change of the surface area during deformation. It is also found that the roughening rate is affected by grain size and the lattice structure of the metal, i.e. the roughening is remarkable in the metal of large grain size and of small number of slip systems. Wave length of the roughness is about 10 times as large as the grain size. Theoretical analysis of the wave length is carried out on the basis of probability.

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