Rotating bending fatigue tests were carried out to evaluate the characteristics of surface crack growth in an age-hardened Al-alloy and an annealed Al-alloy The main results obtained are as follows : (1) The rack growth rate in an annealed Al-alloy is expressed by the following equation. dl/dN = Cσⁿ 1 (C, n : material constants ) The number of cycles to failure of a plain specimen can be estimated by this equation. (2) In case of an age-hardened Al-alloy, a surface crack propagates rapidly along a slip band when the crack is short, and then the crack propagates zigzag, in that time the increase in the crack growth rate is low.

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Two-dimensional elastic stress analysis in plane strain state has been made for adhesive scarf and butt joints. Bending stresses in adhesive layers at distances greater than several times the layer thickness from the free surfaces show almost linear distributions and are zeros near the mid-width of joints. Maximum principal stresses caused by contraction of adhesive are uniform in the region of adhesive layers greater several times the thickness away from free surfaces and their directions agree with the longitudinal directions of adhesive layers. Distributions of bending stresses corrected for the stress gradients by bending and stress distributions caused by contraction of adhesive show mutual similarity in the vicinity of the free surfaces of adhesive show mutual similarity in the vicinity of the free surfaces of adhesive show mutual similarity in the vicinity of the free surfaces of adhesive layers provided the aspect ratios of the adhesive layers are greater than 20 (bending) or 1020 (contraction). Maximum stresses in both cases appear at the corners of free ends of the layers. Bending stresses in this analysis almost agree with those analyzed by photoelastic method.

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This paper deals with a contact stress distribution in bolted joints when a full face metallic flat gasket is interposed between two pipe flanges. Replacing a gasket and pipe flanges by finite hollow cylinders the contact stress distribution is analyzed using three-dimensional theory of elasticity. By numerical computations, effects of the thickness and the stiffness of gaskets on the contact stress distribution are shown. Next, the force ratio of bolted joints with gaskets, which is the ratio of an increment of bolt axial force to an internal pressure and the sealing performance are analyzed. With an application of the internal pressure, a bending moment is produced in bolts. The maximum stress produced in bolts taking this bending moment into consideration is also analyzed. For verification, experiments are performed. Analytical results are in a fairly good agreement with experimental one.

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A problem of stress concentration in an infinite body which contains two spherical cavities of equal diameter and is subjected to uniform tension in the direction of the row of cavities is treated in this paper. A method of solution is proposed for this problem, in which the solution for an infinite body with one cavity is superposed recurrently on the solution of an infinite body without cavity so that the boundary conditions on the surfaces of two cavities are satisfied. The validity of this method is verified by comparing the calculated results with the solutions obtained by H. Miyamoto and with the results by the finite element method. Numerical results obtained by the present method are shown in some illustrated figures.

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We have already proposed a simple procedure for obtaining stress intensity factors by the finite element method. The applicability of the simple procedure for the elasto-dynamic problem is investigated in detail. Particularly, the dynamic stress intensity factors for the opening mode deformation crack are investigated in this paper. The application of the simple procedure is demonstrated with several problems. As sufficient results are confirmed by the investigations, the dynamic stress intensity factors for a centrally cracked rectangular strip subjected t suddenly applied and sustained tension are calculated by using the simple procedure for various ratios of the crack length to the plate width systematically, and the relation of the dynamic stress intensity factor and the static one is investigated.

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This study deals with an axisymmetric oscillatory flow of an incompressible viscous liquid in a circular porous pipe, which starts from rest. Change of the axial velocity profile over an arbitrary cross-section of the pipe duet to a step change and/or an oscillatory one of the flow rate is analytically obtained including a transient component of the velocity in the inlet region. The present analysis is based on Oseen's approximation of the momentum equation and the validity of this method is confirmed by the modified momentum integral method. Dynamic distributions of wall friction and pressure coefficients are precisely discussed on the boundary conditions for oscillatory injection and suction from the pipe wall. Furthermore the following two facts are made clear : one is that slip velocity on the wall has an immediate connection with wall friction, the other is that both the alternating component of the axial velocity and the slip velocity on the wall make the inlet short.

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Oscillatory laminar flows in curved pipes were numerically analyzed and studied experimentally. Flow regimes were classified into seven patterns according to the Dean number De and the Wormersley number α. For large De and α flow pattern was found to change abruptly across a certain boundary. The phase lag of the pressure in De. The friction factors also increased with α, but increased with De following a slight decrease.

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This paper describes local characteristics of heat and mass transfer when humid air is cooled and dehumidified in a tube bank. The tests are carried out for a single tube in a uniform flow and for false tube banks of staggered and in-line arrangements in which the test tube is placed at the first, second or third row and the other dummy tubes preserve flow pattern. Dimensionless coefficients of convective mass transfer Sh. convective heat transfer Nus and overall heat transfer Nu are expressed as functions of Reynolds number Re. Distributions of temperatures and heat transfer rates around the tube are also measured. From the first row up to the third row Sh asymptotically approaches a value analogically predicted from Nu corresponding to single-phase heat transfer. Nus is approximately equal to Nu at the first and the second rows and attains a larger value than Nu at the third row. The data on Sh and Nus at the third row agree well with the average characteristics of the tube banks reported previously by the authors.

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A previous difference method has a geometrical restriction in analyzing numerically thermal conduction problems about materials with any shape. Therefore it has been impossible to generalize the numerical solution of three-dimensional thermal conduction problems by the previous method. In this paper we propose a dual difference method which is free from the geometrical restriction of the previous method. Thereby the application of difference calculus can be extended to two-dimensional and three-dimentional problems about materials with any shape. The accuracy and the relative error depending on the shape of elements were compared and fount out to be smaller than in the previous method. Then, we made an experiment about the induction heating of a steel ball, and compare the experimental results with calculated results by dual difference method. A close agreement between measured and calculated values was obtained.

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A single acting Stirling engine with two pistons is considered to consist of five parts of an expansion space, a heater, a regenerator, a cooler and a compression space. The performance of the engine is easily calculated under the assumptions that the temperatures in those spaces are kept constant at each level through any cycle and that the pressure in uniform in all the regions. Calculations have made clear that the optimum phase difference is about 120°, the optimum ratio of swept volume is about 0.85 and the volume of the cooler affects the engine performance more largely than the other heat exchange volumes.

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C₃H₈-O₂-N₂ mixtures were spark-ignited in a motored engine cylinder, and the mass fractions of CO₂, CO, H₂ and hydrocarbons in the cylinder during the exhaust process were investigated. In the vicinity of the limits of flame propagation in the engine cylinder, branched flames, which propagate at relatively slow speed, appear. In the mixture composition in which the branched flames appear, the mass fraction of CH₄ increases extremely, but no discontinuous changes occur in the mass fraction of CO₂, CO, O₂, H₂, and high combustion efficiency was recognized. Furthermore, the effects of pressure and temperature on the quenching distance were expressed by an empirical equation. Quenching distance at combustion end were calculated, and the change in the mass fraction of total hydrocarbons versus the mixture composition was estimated.

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In this report, the parametric nonlinear forced vibrations of a beam with a mass subjected to alternating electromagnetic force are investigated analytically and experimentally. The beam is fixed at one end, and an alternating electromagnetic force acts on the mass attached to the other end of the beam. In the analysis, the governing partial differential equations are solved by harmonic balance method, and the second order superharmonic and the one-second order subharmonic vibrations are carried out by the Newton Rapson method, and are compared with the experimental results.

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Steady self-excited vibrations of a bowed string, which is perfectly flexible and subject to negative damping due to solid frictional force of general characteristic and to positive damping due to air resistance only, are studied by means of a Fourier series method utilizing series transformation. It is shown that in the limiting case of air resistance tending to zero the obtained solution reproduces the celebrated Helmholtz mode of vibration for a bowed string. The solution also substantiates Raman's results about the necessary bow force to maintain vibration.

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In a self-exciting system of Van der Pol type with the restoring force expressed as the product of a non-linear function of deflection and a periodic function of time, self-excitation and parametric excitation induce resonances of higher orders than orders 1 and 1/2. In the present paper firstly, behaviors in the region of subharmonic resonance of order 1/3 are investigated in the phase plane by using the averaging method. Next an approximate solution and the stability of a parametric resonance of order 2 is determined. In the neighborhood of this resonance a vibration with beat character occurs and then its amplitude is easily obtained. It is ascertained from the results of numerical calculation that the approximate solutions have high accuracy.

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An investigation was undertaken with a view to establishing a procedure for diagnosing the extent of rolling bearing defects from their vibration and sound. In the investigation the vibration of a ball bearing with multiple dents on the race surface of either the inner or outer ring was studied. The inner ring of the bearing was caused to rotate at a constant speed under a given thrust load applied to the outer ring. The radial vibration velocity of the outer ring was determined by a moving coil type converter and using the output so obtained, vibration waveforms were produced. Real time frequency analysis of the vibrations was done by Fast Fourier Transform analyzer and the effect of the measuring position of the outer ring on the vibration, etc. was examined. As a result, the fundamental characteristics of ball bearings having multiple defects were clarified, and an effective method by which to locate the defects and to determine their number and size was established.

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We made an apparatus with a steel rod and a thin steel disk. A disk serving as a railway wheel was clamped at inner radius and was free at its end. When a certain relationship exists among the natural frequencies in the axial direction of the disk, various internal resonances occur. We analyzed a squeal of the disk in internal resonances theoretically. Consequently, in internal resonances between two i-th and j-th vibration modes, such as ω_j=^^ 3ω_i or ω_j=^^5ω_i (ω : natural circular frequency of the disk), squeals with only a frequency of j-th mode and with frequencies of two modes (i-th and j-th modes) occur, but a squeal of a single i-th mode does not occur. If ω_j does not coincide with 3ω_i or 5ω_i completely, a frequency component of i-th mode is predominant in the squeal with frequencies of triple modes occurs. However, its generating region is very narrow.

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Sinking behavior of a very long pipeline installed on the sea floor which transports the cold water and the resources in the deep sea is analysed. In the application of the subsurface tow method, the effects of a horizontal tension caused by a barge and a removing rate of buoys along the pipeline upon the maximum landing velocity and the maximum bending moment of the pipeline are examined by the theoretical and numerical analyses. As a result, it is shown that the maximum landing velocity of the pipeline and the maximum bending moment produced in the pipeline can be decreased by removing the buoys from the shore-side to the offshore-side and by increasing the removing rate and the tension caused at both ends of the pipe.

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The clamping condition of a workpiece and/or a tool has a considerable effect on the machining efficiency and machining accuracy. It is, therefore, necessary to examine the clamping characteristics of chucks and fixtures. This paper describes the clamping characteristics of an electro-magnetic chunk which is one of the most commonly used clamping attachments in a surface grinder. The distribution of magnetic flux density and the normal and the tangential component of the chucking force were measured using the gauss meter and the strain gauge type load cell. From the measured results, the following conclusions can be drawn ; 1) The distribution of magnetic flux density is not uniform, being variable with the perpendicular position to the separator. 2) The chucking force is not always in proportion to the contact area and the relative position between the workpiece and the magnetic poles has a remarkable effect on it. 3) The clamping characteristics are significantly influenced by the contact conditions such as the surface roughness and the flatness of a workpiece.

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Using a two-disc machine, scuffing conditions were investigated with a 0.45% carbon steel refined which is higher in surface hardness and in the ability to form oxide film than the annealed carbon steel in the previous report. The following results were obtained. (1) The scuffing resistance of discs increased proportionally with an increase in surface hardness until the occurrence of scuffing. (2) If the film parameter was below 1 and the surface temperature increased up to the second critical temperature of about 180°C, scuffing took place. (3) It is the condition for preventing scuffing that the surface resistance to scuffing is sufficiently raised during running-in process of light load steps, or the film parameter is kept above 2.

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This paper discussed on a distribution of contact stresses when the cover of a pressure vessel is fastened with tap bolts to a vessel. In the analysis, by replacing the cover and the vessel by a finite hollow cylinder the distribution of contact stresses is analyzed by three dimensional theory of elasticity. In addition, the force ratio, which is the ratio of an increment of a bolt axial force to a load when a pressure is applied, is analyzed by using three dimensional theory of elasticity and theory of beam on an elastic foundation. Moreover, the maximum stress caused in bolts when a pressure is applied, is also analyzed. Then, a method to estimate the pressure causing a separation of the interface and a leakage of fluid from the joint is proposed. For verification, experiments are carried out. Analytical results are in a fairly good agreement with experimental ones.

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The present paper and the companion paper describe kinematic syntheses of planar link mechanisms with only revolute pairs to develop leg-mechanisms of biped machines which walk straight on flat grounds. It has been proposed to divide the leg-mechanism into two sub-mechanisms in order to make a kinematic synthesis possible ; one is an ankle-path-generator which generates a required trajectory of the ankle relative to the upper body, and the other is a foot-driving mechanism which generates a require angular motion of the foot about the ankle joint. The 1st paper discusses type selections of the ankle-path-generator, conditions and procedures of dimensional syntheses and the characteristics of the synthesized mechanisms, resulting in three practical ankle-path-generators.

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The paper describes a kinematic synthesis of a planner link mechanism with only revolute pairs to drive the foot which is attached to the ankle-path-generator obtained in the 1st paper. The ankle-joint angle and foot dimension necessary to realize a required gait have been determined in the case where the ankle-path-generator is predetermined. Then, a mechanism which is composed of a six-bar mechanism fixed on the thigh and a four-bar mechanism on the shank has been proposed and synthesized to drive the foot. A walking machine has been manufactured by combining the synthesized ankle-path-generator and the foot-driving mechanism with a mechanism for compensation of moments due to the gravitational and inertial forces. The machine has been experimentally confirmed to walk satisfying the given conditions.

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Influence of cladding on square cup drawability is examined using model clad sheets of hard aluminium and soft one which have remarkably different-drawabilities from each other. Addition of a hard component at the side portion of he horizontal punch contour and addition of the soft component improves the relative critical strength of a hard component at the corner portion of the horizontal punch contour. The draw ability of only the soft component is thus improved remarkably in contour shapes with a small ratio of corner radius to punch size and both hard soft components are improved in ones with a large ratio of corner radius to punch size.

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