Cyclic uniaxial tension-compression tests with various constant strain amplitudes were performed on mild steel to investigate the change of stress-strain curve in the initial stage of cyclic loading. Strain amplitude was nearly equal to a half of the corresponding prestrain. In order to apply the result obtained to a cyclic elastoplastic analysis, the stress-strain curve in each half cycle was fitted by a polynomial, whose coefficients were examined in relation to the number of half cycles and the magnitude of prestrain. An approximate expressioin for the curve in any half cycle was obtained as a function of the number of half cycles, magntidue of prestrain and coefficients in the expression for the first half cycle after the initial loading.

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In the metal working, friction force between tool surface and worked material gives large influence in the form of plastic deformation of it. Some kinds of experiments are performed in this report concerning non-uniform deformation of a hollow cylinder caused by friction on the interface in axial compression, in order to verify the theoretical results given in the previous report (part 3 of this series of research). Shape of bulges on both the inner and outer surfaces, load of compression distribution of normal pressure on the interface, etc. are measured in various conditions of lubrication, changing the shape of the hollow cylinder. Furthermore, measured values of friction coefficient agree with both the theoretical results by the finite element method and by Kudo's method.

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Formerly, an experiment concerning deformation of an elastic-viscoplastic block compressed oppositely by elastic flat punches was performed for various punch widths. In the test, the effect of punch width became more remarkable with lapse of time in the transient period from the instant of loading to the equilibrium state, while it was not remarkable at the instant of loading. Moreover, the deformation of the block increased with an increase of the punch width, and it was concluded that the effect was due to the time dependence in plastic deformation. In the present paper, to investigate the effect of the block height on the trend obtained in the previous paper, the same experiments are continued for various heights of block. In these experiments, the effects increase considerably with an increase of the block height.

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It is a very important problem that the spin axis of a two-degree-of-freedom gyroscope can't preserve its original direction in case the housing on which the gyroscope is mounted oscicllates. The authors discuss the behavior of the spin axis of a gyroscope mounted on the oscillating housing, and analyze the phenomena theoretically and experimentally. In this paper the formulas of the drift rates are obtained by taking advantage of the fact that one can regard a two-degree-of-freedom gyroscope with two gimbals as a spherical quadric crank chain mechanism in case that the directioin of the spin axis remains unchanged. In the experimental section the drift rates and the amplitudes of the forced vibration are measured for various initial positions of both gimbals and forced frequencies, and resonance is investigated.

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This paper concerns theoretically with self-excited oscillations caused by solid friction. A model, in which solid friction and spring force are applied to a block lying on a moving belt, is used to represent this class of mechanical problem. The solid friction force considered is assumed to vary with the relative sliding velocities between two solid bodies, namely, the friction-velocity characteristic is given by a polygon having two straight line segments and the critical value of static friction is different from the value of kinetic friction without slipping. Several types of limit cycles and the regions in which they occur are shown in figures according to the characteristics of the friction-velocity function. The appearances of amplitudes and periods of limit cycles are also described in nondimensional forms against the velocity of a moving belt for various characteristics of the friction-velocity function.

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Oscillations caused by solid friction are treated experimentally in a rotational system. A ring-like body is connected to a spring and can oscillate coaxially with a rotating shaft under the application of spring force and nonlinear friction force between sliding contact surfaces. Pre-driving of the rotating shaft just after the cleaning of sliding surfaces has a great influence on the characteristic curve betwen kinetic friction moment and peripheral velocity of the shaft. Pre-driving produces a change in configuration of the characteristic curve, therefore the corresponding amplitude-velocity curve and the period-velocity curve obtained experimentally show different appearances from those without pre-driving. These curves are qualitatively similar closely to theoretical ones derived from Lienard's construction.

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In order to make clear the scale effects of the regenerative pump with non-radial vanes, the authors carry out an investigation of the pump performance using 18 kinds of impellers which combine six diameters from 94 mm to 180 mm with three vane angles 60°, 90° and 120° changing the dimensions of the flow channel and fluid viscosity. The following conclusions are obtainded : (1) The influences of impeller diameter on the performance vary with the vane angle. (2) The relations between pump elements and coefficients of shut-off head, flow-rate, torque and maximum value of internal efficiency are made clear. Consequently, the authors give the outline of design method considering the effect of fluid viscosity. To facilitate the description, two examples by the present design method are given. The calculated values agree well with experimental results.

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The main object of this work was to provide data with sufficient accuracy to assist the digital computer study of simulating the process of dropwise condensation which the authors had been developing. Special care was taken in measuring heat flux and steam-to-surface temperature difference during dropwise condensation on both plane vertical surfaces and inclined surfaces. The effect of non-condensable gases which might accumulate near the condensing surface was minimized by making the steam flow with appropriate velocity. Simultaneously, high speed motion pictures and instantaneous photographs were taken through microscope and data on the drop size distribution over the surfaces, the critical radius of drop detachment and the rate of drop growth due to coalescences with neighboring droplets were obtained under vairous conditions.

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In order to study an unsteady cutting mechanics wity varying undeformed chip thickness using such a work material as aluminium, copper and others which has a comparatively low yield point and high work-hardening characteristic, up milling and down milling of a rolled aluminium workpiece and an annealed one are carried out. The distinctive features differed from a steel cutting are found out. Cutting force in down milling increases in spite of a decrease in undeformed chip thickness, and suddenly decreases at the later stage of cutting process. Two patterns of variation modes exist in the variational configurations of cutting force in down milling. It is considered that these phenomena are the general features when cutting these materials and that they result from the varying undeformed chip thickiness and work-hardening characteristic. This consideration is confirmed by calculating the varying depth of a work-hardened layer under a machined surface and by measuring the hardness of the machined workpiece.

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