The behavior of fatigue cracks in plain specimens of pure iron whose mean grain diameter was 0.15 mm was examined by both rotary bending and cyclic torsion tests. The results were compared with those of the previous study using the same material of 0.04 mm in grain diameter. The difference of grain size had not any marked effect on the relation between length and depth of the cracks. The fatigue-notch factor in bending was higher than that in torsion, and the difference between the factors in both tests tended to increase with growth of grain size. The propagation of cracks in torsion was more affected by the orientation factors of crystal grains near crack tips than that in bending. It was found that the grain size was not necessarily dominant for the efatigue-notch factor of cracked specimens.

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In this paper the analytical formulation on the creep of axisymmetric shells subjected to arbitrary unsymmetrical loads is developed for two hardening laws : the time hardening law and the strain hardening law. The fundamental equations derived for incremental values with respect to time, after the expansion of all pertinent variables into Fourier series in the circumferential direction, are numerically solved by a finite difference method, and the solutions at any time are obtained by integration of the incremental values. In conclusion the computer programs are developed which can be used to predict the creep deformations of axisymmetrical shells under arbitrary loads. As a numerical example the creep deformation of a cylindrical shell of importance in practical use is treated.

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A cylindrical reservoir supported partially by two saddles is of the most universal type of horizontal reservoirs. In this paper, we tried to find a say to support profitably a reservoir of such a type. The relations of stresses and deformations of a reservoir under saddle reaction forces are investigated. The stresses and deformations are found as the solutions of the differential equations for cylindrical shells introduced by the senior author. Moreover, the effects of end plates on the strength of a reservoir are discussed by researching the relation of saddle location to the stresses in the reservoir. The results of our analyses show the following facts ; Using saddles having suitably rounded edges, the reservoir can be supported without making the local stresses so large. In the case of a reservoir supported in its cylinder part, the saddles sink into the reservoir to make the stresses large in the vicinity of them, so locating the saddles under the end plates is more profitable.

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The authors propose two kinds of method (Front Surface Method, Back Surface Method) by applying the X-ray measurement to a destructive method of removing thin layers to obtain three principal components of residual stress in a multi-layered cylinder composed of many elements of different materials and give the calculating formulas for every method. The formulas⁽¹⁾⁽⁴⁾ for a single cylinder can be derived as a special case from the present ones. As applications of the authors' two methods, they measured the residual stresses of a two-layered cylinder produced by the external or internal chromium deposition on a hollow carbon steel cylinder and compared them with the results obtained by applying the Strain Gauge Method⁽⁵⁾ to the same specimen. In a general multi-layered cylinder, the elements have different linear expansion coefficients, so that the residual stress distributions must be affected by temperature. The authors emphasized that the temperature of measurement should be set at a standard temperature and showed the correcting formula of residual stress for a changed measuring temperature in two-layered cylinder.

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The stresses in composite models with application to cemented joints, especially those by butt bonding, were studied by using the photoelastic and interferometric methods. The models were made of epoxy-poly sulfide copolymers. Tests were carried out under tension on a composite bar bonded at various interlayer breadthes. The results of experiments revealed that the stresses near the bonded boundary were not uniform and that in the joints with a soft adhesive layer, the stress concentrations were found on the end or center of bonded boundary in hard adherends, and they were almost reduced depending upon the decrease in the value of the breadth of adhesive layer. And in those with a hard adhesive layer, they were found on the end of bonded boundary in the hard adhesive layer, and they were increased depending upon the decrease in the value of the breadth of adhesive layer.

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By investigating the applications of Saint Venant's principle to dynamic problems, the stress wave propagation in a semi-infinite body subjected to an impulsive torque on the surface of a hemispherical pit is analyzed. The effect of the shear force distribution and the force variation in time on the impact stress is studied. The following results are obtained. In the case of a torque applied step-wise, the stress near the wave front is heavily influenced by the distribution of shear force on the surface of a pit. But in some time after the wave front is carried, the stress at a point far from the pit has no relation to the distribution of the shear force. The longer the rise time of the force, the smaller the influence of the distribution of shear force on the impact stress becomes.

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A rotating shaft system composed of a circular disc, an elastic shaft and two bearings is usually subject to some gyroscopic effect and has four natural frequencies p₁p₄ which correspond to four modes of whirling motion. Of these four, the first two are of forward precession (p₁>p₂>0) and the other two are of backward precession (0>p₃>p₄). We consider a vertical shaft system, in which a shaft is supported by a double-row self-aligning ball bearing at the upper end and by a single-row deep groove ball bearing at the lower end. If the two center lines of the upper and lower bearings are well aligned and if the shaft is situated at the middle of the angular clearance of the lower bearing, the elastic restoring force of the shaft has symmetrical nonlinear spring characteristics. For this rotating shaft system, summed-and-differential harmonic oscillations of the types [2p₂p₃], [2p₂-p₄], [p₂-2p₃], [p₂-2p₄], and [p₂-p₃-p₄], and a subharmonic oscillation of order 1/3 of the type [3p₂] can occur. In this paper, these nonlinear forced whirling oscillations are studied experimentally. Furthermore, it is pointed out that the polar coordinates are suitable for representing the nonlinear restoring force characteristics in these whirling oscillations.

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Regression equations for controlling sand mixing units in casting process by a small scale on-line computer are presented. Exponential smoothing method is used jointly to predict slow variation of sand properties, resulting in reducing storage requirement for control computer. Controller consists of two hierarchial computing system; an off-line large scale fast computer and a small scale on-line computer (mini-computer). The former revises the regression coefficients in a daily mode, by which the latter decides steering variables for the day's operation. Experiments are carried out in some commercial plant. The results do not show any observable differeces between the usual operation by human control and computer controlled experiments.

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Aerodynamic effects of the thickness of a boundary layer (δ_s) developed on an end wall facing a wing tip, the size of a tip clearance (s) and the angle of attack (α) on the lift and drag of a wing in a low-velocity flow are considered, and the correlations between local or total lifts and drags are discussed. Variations of the spanwise lift depend merely on a s under introduction of a dimensionless parameter, which includes a retained lift determined experimentally at the wing tip. Variations of the spanwise drag coefficient (c_D) against y_t/δ_s at s=0 depend on α in the flow region, in which aerodynamic effects of the boundary layer are predominant, but are independent of δ_s ( where y_t denotes the spanwise coordinate). Variations of c_D against y_t at s≠0 are expressed approximately by an exponential function, by use of which the total drag is given by a simple expression.

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The growth of the vortex-pair developed behind a circular cylinder was investigated experimentally, when the cylinder was moved impulsively in a water tank. The experimental conditions were Re = Ud/ν = 10²2×10³, d/h =0.040.67 where U is the cylinder speed, d the cylinder diameter and h the distance between side walls of the tank. The detailed patterns of the vortex sheets and path lines around the cylinder were visualized by means of electrolysis and Al-dust methods. When the ratio d/h is decreased to 0.1, the effects of the tank walls on the flow are substantially negligible. The vortex sheets roll up near the separation points when Re> 520 and a secondary small vortex-pair is formed on the upstream side of the main vortices. The pattern of the vortex sheets shedding from the secondary vortices changes as Re is increased. This phenomenon is closely related to the manner of growth and collapse of the main vortices. The wall effects were examined within the range of d/h = 0.10.67. When d/h>0.5, the separation of flow occurs also at the side walls and "wall vortices" are formed. These vortices deform the pattern of main vortices behind the cylinder.

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An investigation was carried out on various characteristics of a circular cylinder with tangential injection of air immersed in a uniform flow. As a result, it was found that a separation bubble took place where the radius of curvature of the cylinder was discontinuously increased even if the wall itself was smoothly connected; that the velocity profile of mixing region of jet was similar and cosine-like up to downstream of separation-point; that, when the intensity of jet was weak, the lift (drag) coefficient was reduced (increased) by injection of air when the station of the slot was up-stream of the laminar separation-point and that, when the station of the slot was downstream of the laminar separation-point, the control to fix the separation-point anywhere between the laminar separation-point and the station of the slot was impossible.

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This paper presents the effect of the side walls of a wind-tunnel on the flow around a circular cylinder and its wake in the N.P.L. type wind-tunnel having the test section of 60×60×310cm. and the dimensions of Karman vortex-street are observed in the water tank. The results are discussed by comparison with those of the investigations so far made.

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An interesting flow phenomenon in a cross-flow impeller --- an asymmetrical throughflow in a geometrically symmetrical impeller --- has been investigated experimentally. The causes of the throughflow are explained in relation to the flow mechanisms. Flow was visualized by moire method of topography and solid particles. The transient process of the flow from the starting of an impeller until formation of a large eccentric vortex was observed in details. If Reynolds number is larger than 250, the throughflow occurs in all the types of the impellers experimented. In the steady rotation of the impeller the eccentric vortex rotates slowly around the impeller-axis and flow pattern changes sequentially. The change of flow patterns is essential to the flow of the cross-flow impellers.

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The effects of a cone vertex angle θ on the frictional moment of a rotating cone were investigated experimentally over a range of vertex angles from 30° to 270°, when the cone was rotated in a conical casing the vertex angle of which was equal to that of the rotor. In the case of 120°≤θ≤180°, the moment coefficient C_M was found to be almost independent of θ in any flow regime, but at θ≤90°, a fairly large difference of C_M due to θ was observed in the region where the spacing ratio s/r₀ was comparatively large and the Reynolds number was small. Visual study of flow was conducted at θ = 180° (disk) and θ = 60°. It was deduced that, in the case of θ = 90°, vortices similar to those of Taylor type occurred in the flow.

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A mathematical model of the sonic oscillator operated by air is introduced. The basic equation describing the behaviour of the oscillator is reduced to a nonlinear difference-differential equation due to the distributed parameter interconnecting conduit, while the equation for the oscillator having no chamber in the control ports is reduced to a nonlinear difference form, which can be solved by a graphical method. It is shown by analysis that many features of the phenomena occurring in the oscillator can be comprehensively explained by means of the mathematical model, including the oscillator operated by water as a special case. Theoretical results derived from the model are in good agreement with experimental results.

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The statistical characteristics of ebullition of single superheated water drops in liquid paraffin were studied. The ebullition rate was found to be nearly proportional to the initial surface area of a drop and to increase with the rate of the temperature rise. It was also shown for the case of the temperature increasing monotonically with time that this statistical event is well arranged by the probability density for the temperature at the time when ebullition takes place. The qualitative interpretations of above results were presented.

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The blow-out limit of an air-atomized spray flame is studied. After some characteristic features of the results are discussed, a simple semi-empirical formula is presented. The flame base is stabilized in the recirculating flow region when the primary air flow rate is above the critical one The blow-out limit under this condition can well be expressed by a formula in which Craya-Curtet number c_ti, characteristic values of temperature and fuel mass concentration T^* and c^* are involved.

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In this paper, a new method using edge tone nozzles has been introduced for the purpose of improving three combustion characteristics, that is, the strength, stability and flame shape. Then the following subjects were examined by using several nozzles which are different in dimensions; (1) acoustic characteristics of nozzles and interactions between acoustic waves and combustion, (2) improvements in combustion strength and stable combustion region, (3) intensifying and stabilizing mechanisms, and (4) necessary strength of high frequency disturbance. The obtained results show that this method is effective to improve the above three characteristics simultaneously. Particularly, it has been found that flame shapes are altered by the secondary flow toward nozzle which is generated by the nozzle warping. The zigzag movements of combustion moles, which are caused by high frequency turbulence above 10 kHz, improve the strength and stability, and pressure variations over 60 mmAq are required to obtain high combustion efficiency.

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