A mechanical type of random fatigue testing machine is improved so that random loads with arbitrary overall means can be applied to the specimens. Random fatigue tests are then carried out by the testing machine both on hard steel (S55C) and aluminum alloy (7075-T6) in order to examine the utility of the machine and to determine the fatigue strengths or the fatigue lives of both materials under service loads. Further, discussions are made about the appropriate methods both of load counting and of estimation of fatigue lives under service loads. Consequently, the full wave count method is proved to be very useful since the fatigue lives estimated by that method are closer to the actual lives, irrespective of the material and the extent of the irregularity of the original random load.

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Low cycle corrosion fatigue tests of a high strength steel were carried out in 1 % NaCl under the primary trapezoidal stress wave form superimposed with the secondary stress fluctuations of small amplitude during a holding period at maximum load, and the following results have been obtained. The influences of small secondary stress fluctuations during a holding time in primary trapezoidal wave forms are far more dangerous in corrosive environment than presumed in air, and the corrosion fatigue life remarkably decreases when the secondary stress waves are applied However, balance between mechanical damaging action and corrosive action is reached at the total amplitude of secondary waves Δσ= 0.15 σ_max, which increases the fatigue life owing to the suppression of crack initiation. Though the propagation rate of corrosion fatigue is insensible to secondary stress fluctuations of small amplitude, the rate increases monotonously with an increase of Δσ over a limiting value (ΔK₁ = 10 kg·mm^(-3)/2.The secondary stress fluctuations increase also the thinning due to corrsion and fatigue deformation of materials.

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There have been treated some thermo-elastic problems of a heat source in the steady-state heat condition. In this paper, the stress analysis of a circular inclusion between point sources producing heat and absorbing it in an elastic plate is made, under the assumption that all the heat flowing out from the heat source passes through a circular inclusion or near it and flows out from the sink heat source, being always kept under the steady-state heat condition.

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Discs of uniform thickness with a hole at the center were molded by winding the prepregs of glass fiber roving with polyester resin. A circumferential crack occurred in the disc when the inner to outer radius ratio of the disc became larger than a certain critical value. It was found that this crack was due to residual stresses in the disc developed in molding process. The distribution of residual stresses in the discs were analysed by considering anisotropic shrinkage of impregnated roving during the setting and cooling processes. These theoretical results approximately coincided with experimental results. From these results, it was made possible to predict the critical value of the inner to outer radius ratio less than which the crack did not occur in molded discs. It was also shown that the autofrettaged discs with arbitrary inner to outer radius ratio could be molded by anisotropic shrinkage of resin impregnated roving.

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The method of computing the stiffness constants of a curved beams by a simple finite element approach, where the beam is considered as a cascade-connection of straight elements, is used for the calculation of transfer-matrices of elasticity M^^-. Usually the calculations are carried out directly in numerical level by using an automatic computer according to the formula M^^- = M₁·M₂……M_n, where M_i is the transfer-matrix of the i-th element. By this method, however, an accumulation of errors decreases the accuracy, and few papers treated the characteristics of these matrices in general cases. In this paper, the author presents general explicit representations of matrices M^^- for two-dimensional curved beams. It is shown that the resultant matrix M^^- = M₁·M₂……M_n, where M_i = T_i(λ_iI+Φ_i), is generally representated in analytic-explicit forms, provided T_i is commutative-orthogonal and λ_iI+Φ_i are some triangular matrices. According to these results, the dilemma of increasing errors in the calculation against an increased number of partitions in order to obtain more precise results can be removed.

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Spherical tanks at present are designed so as not to break down or collapse even when they are exposed to a typical earthquake like the El Centro. However, if the oil damper is applied to the tanks, their resistance to earthquakes will be increased even more. This paper deals with a theoretical analysis on the suitable damping coefficient of a double acting damper fitted horizontally between the bottom of the tank and its base. In the theory, the optimum damping was selected to minimize the transmissibility resonance curve in the predominant frequency range of earthquakes. A scheme for the application of the damper was proposed, with which forced and free vibration tests were conducted for an actual 200, 000 m³ gas tank with and without a damper. As a result of the studies it was proved that the application of a damper to spherical tanks is very effective in increasing their resistivity to earthquakes.

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To clarify the dynamics of the derailment of a 2-axle railway wagon caused by the lateral hunting motion, a mathematical model of the 2-axle wagon which is applicable even to the phenomenon similar to the derailment, is formulated. With this simulation model the dynamics of a 2-axle wagon on the track with irregularities is investigated making use of a digital computer. Results of the simulation are compared with the experimental results, and the adequateness of the model is confirmed.

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Precise position control with an accuracy of 10 μ was impossible by mechanical means such as screw movement used so far. This is because continuous movement couldn't be expected due to sliding friction from a microscopic point of view. Also, it was impossible to avoid backlash even though mechanical pressure by spring may be adopted. The authors have developed practically precise control with an accuracy of 0.2 μ by a new method utilizing the electromagnetic force. In the new equipment, dynamic characteristics are also excellent because the damping time can be designed independently of characteristic frequency by electrical damping and because resistance to deviation from exact position can be selected widely by electrical feedback from a laser interferometer. For example, 66 g-wt is necessary to move it 0.1 μ in the case of only 0.56 W electromagnet, and the time taken for it to become stationary is less than 100 msec at the present stage.

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The flow characteristics of rarefied gas through a pipe orifice having an orifice plate of finite thickness is studied in the intermediate regime of rarefaction. The resistance and the pressure distribution are measured with emphasis on the effects of thickness of the orifice plate. The dependence of the overall conductance of the Knudsen number refers qualitatively to the case of a sharp edged pipe orifice which has been presented in Part I. As the flow approaches the free molecular limit, the conductance tends to a different constant value from Bureau's one. An improved formula to predict the overall conductance at the free molecular limit is proposed by the combination of conductances for a short tube and for a sharp edged pipe orifice. In the intermediate flow regime a method to estimate the overall conductance is also discussed, and an approximate formula for small pressure ratio is proposed comparing with the experimental results.

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The studies to measure the unsteady flow by means of a combined probe were shown in the previous papers. However there have been left two problems unsolved: One of them is the convenient procedure to process great many time-series data, and the other is the way to confirm the accuracy of the measuring systems. These means were established by using a digital data processor, improving the experimental devices and developing the computer program. In this paper, the calibration procedure of a combined probe is presented and the error estimation in flow measurements is discussed with the application of characteristic polynomials which are derived from the regression analysis for the calibration data using digital computer. To formulate the probe characteristics as polynomials is greatly useful in measuring unsteady or steady multi-dimensional fluid flows.

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A wall-attached fluidic element is caused to oscillate by interconnecting two control ports with a conduit. The oscillator is termed a sonic oscillator, which is usually operated by air. In this study, however, a mathematical model of the oscillator operated by water is introduced and its propriety is examined experimentally. The basic equation describing the behaviour of the oscillator is derived from several assumptions and it results in the generalised equation of Lienard. On the basis of this equation, the mechanism of oscillations is theoretically investigated and it is shown that oscillations are caused by the negative resistance in the input characteristics of the wall-attached element. Theoretical results are in satisfactory agreement with experimental results.

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In this paper, an oil hydraulic pipe line system terminated by a vibrating valve at one end and a constant pressure source at the other is discussed. The wave form of pressure pulsation and the mean flow rate of the system are calculated by an approximate method considering a nonlinear pressure-flow characteristic of the valve. In these systems, in spite of sinusoidal inputs of valve orifice areas, higher harmonics are generated and the mean flow rate is changed according to the frequency even if the mean valve orifice area and the mean pressure difference remain constant. Using a hydraulic pipe line-spool valve system, the pressure wave form and the mean flow rate are examined experimentally. And the results are compared with the calculating results. Agreement of both results is fairly good.

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Oil-hydraulic control valves sometimes become unstable if they are not well-designed. It is often experienced that the stability limits of the unstable phenomena depend on the characteristics of disturbances. However, the threshold of stability limit has not yet been clarified by using only the usual linear theory which is inadequate to consider the nonlinearity of the phenomenon. In this paper, the stability limits of the oil-hydraulic systems with spool-type pressure control valves are investigated both experimentally and theoretically, under conditions of sinusoidal disturbances with various combinations of amplitudes and frequencies applied to the systems. It is found that the nonlinearity of Coulomb frictional force acting on the sliding surface of the valve spool is one of the main causes of the specified stability of the system. Furthermore, the effects of valve configuration, rate of flow, and pipe length on the stability limit are clarified.

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An experimental study has been made on a turbulent heat transfer of air flow on an evaporating water surface in two cases : the case of heating a water surface with a flow of hot air and the case of cooling a water surface of high temperature with a flow of cold air. Heat transfer on the water surface is found to be higher, in both cases, than that on the solid surface. Then, a comparison between experimental and theoretical value is attempted on the equilibrium temperature of water surface, clarifying that the analogy is nearly established between heat and mass transfer within a turbulent boundary layer on a water surface. Velocity distribution in turbulent boundary layer is also measured, and it is found that the velocity profile on a water surface is different to some extent from that on a solid surface. Measured temperature fluctuation in a turbulent boundary layer reveals that the fluctuation is considerably greater than that in a boundary layer on a solid surface. The results afore-mentioned mean that the increase of heat and mass transfer occurs due to a rise of turbulence in a turbulent boundary layer on an evaporating liquid surface. However, the mechanism of the increase of turbulence has not yet been revealed.

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In regard to the stability of a diffusion flame in which air and fuel stream impinges at right angles to each other, from the experimental study the following factors could be found very effective to increase stability of the flame : (1) to make mixture ratio near-stoichiometric (2) to make velocity of fuel-air mixture flow small (3) to increase burner port temperature high From these results, to make sure the stability of flame of such a system, a new flame stretch theory was advanced. In the theory, it was assumed that at anchored point of the flame, concentration is stoichiometric. From velocity and concentration profile in the cold model, a stretch factor in the hot system was assumed. Under such assumptions, the results of calculating flame stretch factors were almost constant.

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The pattern of temperature distributions of gases in the combustion chamber of a rapid compression machine and in an internal combustion engine will be complex. And in this report, a successive approximation equation which gives the gas temperature measured by the infrared radiation pyrometer has been derived under the condition of nonuniform temperature distributions. The results agree with the measured temperature and the characteristics of the pyrometer have been investigated with hive model distributions which will occur in the combustion chambers. The pyrometer gives a little higher temperature than the average and the tendency will be more intensified as the ratio of the highest temperature to the lowest departs from unity and temperature levels become lower. The gas near the radiation detector affects the reading more than that located farther apart. Some examples to calculate the peak temperature of the gas in a combustion chamber have been presented.

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The design equations of an offset slider-crank mechanism to satisfy the first four precision derivatives of an ideal function are presented. The development of the equations is based upon the geometrical relationship of the "conjugate" slider-crank mechanism and the return circle of its coupler relative to the fixed link; the task of synthesis is thereby greatly facilitated. The derived equations take simple forms; and the numerical calculations can be performed readily and accurately with the aid of a desk calculator.

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This paper deals with the theoretical and experimental studies on cylindrical gears of two types which have no behaviours of driven gears under any load. The one is a gear which is named "double spur gear". The double spur gear is built up of two spur gears whose contact ratio is 1.5. These spur gears are fixed in such condition that they are staggered from each other by half pitch. The other is the profile modification for a helical gear by a new method. The profile modification for the helical gear must be performed either about the tip area of the pinion or of the gear. This method is proposed after a study on the meshing conditions of the helical gears under the transmitting load. These double spur gear and the profile modified helical gear showed good ability for the meshing test under any load.

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The mechanism of chip formation in wood cutting differs essentially from that in isotropic materials. The authors propose a calculating formula of cutting forces in orthotropic material of wood considering the typical split ahead of tool in orthogonal wood cutting. The authors adopt a simplified model to make clear the basic cutting mechanism and introduce an approximate calculating formula by extending the theory of beams on elastic foundation and that of linear fracture mechanics. The calculating formula is expressed as a function of elastic modulus of wood species, chip thickness, rake angle, tool width and frictional coefficient. The calculated values from the authors' formula agree well with the experimental ones with respect to the variations in wood species, chip thickness, rake angle and tool width.

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