An asymptotic method of multiple scales has been used to model wave propagation normal to the layers of a tri-laminated composite where each of its major constituents is sandwiched between two bonding layers. The model has the form of mixture equations of three constituents and two common directors. The efficacy of the model is assessed by comparison of predicted and exact phase velocity spectra and stress profiles in the cell for time harmonic waves. It is also found that the influence of the bonding agent on the first mode phase velocity spectrum is insignificant. However, a significant variation of the stress in the bonding layers suggests the necessity of the proposed model which can recover a continuous stress-microstructure in the cell.

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Tensile strain hold-time experiments have been made with a type 304 stainless steel at 750°C in air and in vacuum of about 1×10^-5 Torr. The hold-time effect is observed to be more remarkable in vacuum than in air. The present data show that the frequency approach and the creep-fatigue interaction approach are insufficient for evaluating the difference of the hold-time effect in both environments. A new approach based upon the linear damage rule which is successfully applicable to evaluate the effect of environment on high temperature low-cycle fatigue has been proposed. It has also been shown that the present approach can predict the difference in a fracture face-fatigue type and creep type-observed in vacuum tests.

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Corrosion fatigue crack growth test of a high-tension steel HT55 was conducted in 1% NaCl, and the wedge effect by corrosion products and crack extension by corrosive dissolution have been estimated in terms of ΔKeff. da/dN against ΔK in 1% NaCl decreases in the order of 0.01 Hz, 0.1 Hz, in air (having no frequency effect) and 5 Hz under R=0.1. da/dN in NaCl at 5 Hz is smaller than that in air on account of the wedge effect by corrosion products. There is no wedge effect under R=0.5. When the wedge effect is eliminated by re-plotting the results in terms of ΔKeff, da/dN under R=0.1 decreases in the order of 0.01 Hz, 0.1 Hz, 5 Hz and in air as is under R=0.5. Supposing the linear summation hypothesis in terms of ΔKeff, the crack extension by corrosive dissolution (da/dt)_D is reduced.

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Sustained load stress corrosion cracking (SCC), Cyclic SCC (FSCC) and corrosion fatigue tests in 3.5% NaCl were performed on sensitized high-strength Al alloy specimens having various thicknesses. The SCC crack growth results from alternation between a crack growth of an anodic dissolution at grain boundaries and a brittle fracture of a ligament zone by hydrogen embrittlement. The influence of specimen thickness is observed not only on the threshold value for SCC crack growth K_ISCC but on the threshold value for FSCC crack growth K_FSCC ; the greater the thickness is, the lower the K_ISCC and the K_FSCC are. It is significant that the lowering of K_FSCC against K_ISCC becomes remarkably greater in a thick specimens. The thickness effect on the SCC and FSCC crack growths can be explained by the difference of constraint condition at crack tips.

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The temperature of specimens during the fracture toughness testing, varies due to the heat generation associated with a plastic flow near the crack tip. The temperature has been analyzed using a simple heat balance model and the generated heat has been calculated. Heat generation rate changes in a clear slope corresponding to the stable crack initiation. Hence, this phenomenon can be used for detecting the stable crack initiation. J-integrals were estimated based on the heat variation for three kinds of steels and were found to be close to the ones evaluated by the R curve method.

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Stress concentration factors of grooves in round shafts under torsion have been investigated by several investigators theoretically and experimentally. But those previous results disagree considerably. In this investigation, the accuracy of those results was examined for semi-circular grooves by means of the electro-plating technique. the experiment was carried out by using a particular procedure so as not to allow an error to be caused by a preconception of the investigator and the difference of experimental conditions. The result shows that the numerical values obtained by Nishitani et al. and Matthews et al. are reasonable.

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This paper presents a transient analysis of the propagation of stress waves arising in an elastic half-space subjected to concentrated tangential force varying with as the Heaviside unit step function on the surface. The solution of such a non-axisymmetric problem is obtained from the three dimensional elasto-dynamic theory. The wave motion equations can be obtained by introducing the stress functions ψ₀, λ₂ and λ₃. The boundary conditions of the external force are satisfied with the aid of the Hankel transform method and the Laplace transform theorem. The Laplace inverse transfomrs are accomplished by procceding with the integration along Bromwich integral path. The results of numerical evaluation are shown graphically as the relation of the displacement and the stress variations versus time in elastic half-space.

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Effect of an attached mass and damping on the stability of cantilevered articulated pipes conveying fluid is studied theoretically and experimentally in the case of two degrees of freedom. The transference of flutter-type instability from one branch in root locus diagram to another is discussed. This transference of the instability between two branches is one of the interesting phenomena in this type of non-conservative problems. Stability analyses by Hurwitz criterion are made with and without damping. It is shown by theory and experiment that the theoretical prediction without damping leads to undue stability limit when a big mass is attached near the discharge end of a cantilevered system.

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Using slip-initiation phenomenon by fatigue in an electro-deposited iron, we propose a method of measurement of the stresses in machine elements under fluctuating service loads. In the method, both the direct iron-plating and adhesion of deposited iron-foil are utilized. Accuracy of the iron-foil method, however, is far superior to that of the direct plating method. Basic properties of the iron-plating for stress measurement, namely, applicable test temperature, and effects of test interruptions and grain size of the plating on slip-initiation are examined. When the iron-foil method is applied, the stress-concentration factors in notched specimens are obtained at various temperatures. The results are in good agreement with the theoretical and experimental values obtained previously. Consequently, it is confirmed that the present method utilizing the deposited iron-foil is effectively applicable to the measurement of cyclic stress in the range from room temperature to 250°C.

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Methods of measurement using interference patterns of diffraction beams are effective in measurement of in-plane strains of plane surface of objects. This paper deals with a new method of measuring the first order derivatives of displacement. In this method an interferometer with a triangular, looped path is used and two beams producing an interference pattern pass the same, looped path clockwise and counter-clockwise respectively. Merits of this method compared with usual methods are as follows : (i) errors in interference fringes caused by unevenness of surface of mirrors, distortion of wavefront due to aberration of a collimator lens and non-uniformity of thickness of film (or specimen gratings) are compensated sufficiently for the practical purpose, (ii) diffraction beams of high order can be used and high sensitivity in measurement is achieved, (iii) the optical arrangement is simple and adjustment is easy, and (iv) the interference pattern is stable against shock or disturbance.

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Since a typical supercavitating hydrofoil has a sharp leading edge, its chordwise bending deformation and oscillation become a serious problem. Expressions are presented for the pressure distribution, lift and drag of a thin hydrofoil performing chordwise bending oscillation when clampted at the trailing edge at zero cavitation number. By using these expressions, chordwise bending flutter, chordwise bending divergence, strength near the leading edge and cavitation inception on the pressure side are investigated numerically. From the results have been deduced the following ; (1) The critical speed of cavitation inception on the pressure side is lower than the critical speed of chordwise bending divergence. (2) To give a slight thickness near the leading edge is very effective for increasing the critical speed of chordwise bending flutter and cavitation inception on the pressure side or decreasing the stress due to chordwise bending.

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Hydroelastic instabilities of elastic supercavitating hydrofoils on elastic supports are investigated. Expressions are presented for the pressure distribution, lift and moment acting on the oscillating foil which is chordwise flexible and elastically restrained in translation normal to the free-stream direction and in rotation about a prescribed axis which is normal to the plane of flow. By using these expressions, critical values of chordwise bending flutter, chordwise bending divergence, bending-torsional flutter, torsional divergence and cavitation inception on the pressure side are obtained numerically. From the results it has been deduced that chordwise bending flutter is possible but chordwise bending divergence is not. Furthermore it is shown that bending-torsional flutter boundary is influenced considerably by chordwise flexibility in high speed flow.

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The wave phenomena in a linear tapered tube were experimentally investigated by the step pressure input. In this report, we compared these experimental results with the theoretical results shown in the first, second and third reports. And we obtained the following conclusions. (1) In the experiments, various wave phenomena in a linear tapered tube were observed, and these results almost agree with the analytical solutions of the one-dimensional wave theory shown in the first, second and third reports. (2) The wave history at the end in a compound tube which is composed of a linear tapered tube and a tube with uniform cross section is similar to that at the end in a simple linear tapered tube. (3) Even in the compound tube, the analytical solution can be obtained by the method of eigenfunction expansion.

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This paper describes in detail some investigations relating to shock tube orifice flow experiments and its model calculations. The accuracy of the analytical results of the model has been checked by shock tube experiments. In addition, this model results are also compared with the steady flow data namely, ASME Tap relations and existing data relating to supercritical flow regime. The following results are obtained : (1) The pressure loss of orifice can be well estimated by our model calculations. (2) The agreement of compressible flow coefficients between shock tube model calculations and steady flow data is seen in both cases of subsonic and supercritical flow regimes. (3) These results hold not only for κ ( : ratio of specific heats) =1.4 (air) but also for other gases.

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A step response of hydraulic servomechanism under influence of compressibility of oil is studied. Firstly basic equations for a closed loop system under a general loading condition are studied. Secondly time dependent variation of pressure in the system and displacement with no-load condition are studied. An exact solution in an analytical form is given for this case. The compressibility of oil considerably influences pressures in the system, wheras its influence on the displacement response is small. The response under constant loading force is similar to the response without loading. When a few parameters are transformed suitably, the response with constant load or the Coulomb friction coincides with the response of the no-load system

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Step responses of the hydraulic servomechanism under spring load, viscous load and orifice load are studied considering the influence of the compressibility of oil. Some basic characteristics of the system are analized and an exact numerical analysis is performed with various combinations of system parameters. The influence of the compressibility of oil on the output displacement under these loads is comparatively small. The calculated results reveal that the output displacement obtained under the assumption of incompressibility of oil gives fair approximation in most cases. The influence of the compressibility of oil on pressure variation in cylinder chamber, which is small under the spring load, becomes large under the viscous and the orifice load. The system is generally stable under these loadings.

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Corrugated wall channels are investigated as a means of augmenting the forced-convection heat transfer with a single-phase flow in heat exchangers. At the first step of systematic studies to examine adequate configurations of corrugated wall channels, fluid flow states and heat transfer characteristics of laminar flows for parallel channels bent perpendicularly two times as fundamental elements of corrugated wall channels are calculated numerically for various values of pitch by a finite difference method. Consequently, aspects of flow, wall shear stress distributions, pressure losses, local Nusselt number distributions and heat transfer augmentations are shown, effects of bending are clarified, and adequate values of pitch are examined.

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This paper presents an experimental study of transient turbulent heat transfer from a flat plate with a constant heat capacity. The flat plate which is set parallel to a uniform flow is initially at the same temperature as the flow, and the plate is heated stepwise with time. The responses of turbulent heat transfer on the plate were studied experimentally. Transient local wall temperature of the plate was measured using a vacuum deposited nickel thin film as a resistance thermometer. The relations between dimensionless wall temperature or Spalding function and dimensionless time are shown. Close agreement between measured and analytical results was obtained within the experimental errors.

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The transient phenomena induced in the case where a gas slug grows rapidly due to a very high evaporation rate of liquid or a drastic decrease of system pressure, were simulated by using an air-water flow system and experimentally investigated with special attention paid to the dynamic behavior of liquid film around a gas slug. Meanwhile a theory was proposed to express the thinning process of liquid film around a gas slug in a transient motion. As a result the following were made clear : When the film thickness is measured at a fixed point on a pipe wall, it decreases with time in both the cases of transient and steady flows. But the greater the growing rate of gas slug, the greater the decreasing rate of film thickness. The transient behavior of the film thickness can be predicted by the proposed theory with a sufficient accuracy.

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A method is presented to analyze the vibration of a complex mechanical structure by using the natural modes of the components. A structure is divided into some components. All components are classified into master components ana branch components. The natural modes of each component are determined separately by the finite element method. The natural modes of all components are synthesized to form the generalized system coordinates. The equation of motion under these system coordenates is solved to know the vibration of the total structure. The vibration of a rectangular plate is analyzed by this method, changing some calculative factors. On the other hand, the vibration of this specimen is measured under the harmonic exciting force to get the natural frequencies and the natural modes. The calculative results are compared with the experimental ones to check up accuracy of the calculation and availability of the proposed method. It is clear that this method is useful for analyzing the vibration characteristics of complex structures.

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This paper describes a finite element analysis of elastic bodies with many contact surfaces and the applications of this method to the stress analysis of threaded connections. It is shown that the stress distribution in the threaded connections with dimensional modifications such as differential pitch and flank angle is analyzed by this method as easily and accurately as in the normal threaded connections. The stress distributions in the double nuts connection and flange coupling clamped with bolt and nut which have not been clarified previously are analyzed by this method. The results obtained confirm the utility of this method in engineering science and practice.

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Various analyses on the hydrodynamic lubrication of the piston ring with a parabolic shaped face have already been carried out by a number of researchers. However, the boundary condition of oil-film pressure which affects the theoretical oil-film behaviour has not been sufficiently studied in their analyses, because it is quite difficult to measure the oil-film thickness and/or the distribution of oil-film pressures accurately. This paper refers to an optical measurement of the oil-film behaviour of a circular faced slider which reciprocates on an optical flat without a tilting motion. Both the squeeze velocity and the separation boundary of the oil-film are simultaneously measured by means of a thin film interferometry, and their relation is compared with the theoretical relations based on various boundary conditions. Consequently, it is recognized that the Reynolds boundary condition is the most conformable of all conditions with the experimental results.

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Experimental and theoretical studies have been done on the frictional noise without lubrication when a steel rod is pressed in the radial direction on a rotating thick disk with periodic corrugation surface. When the surface roughness becomes larger, various resonances are observed in the frictional noise and acceleration because of the nonlinearity such as loss of contact between the rod and the disk. That is higher harmonic resonances, subharmonic resonances, higher-subharmonic resonances of the fundamental lateral natural frequency of the rod, the fundamental and higher harmonic resonances of the higher mode of the rod are observed. Moreover, the differential and additional harmonic resonances of the fundamental and 2nd lateral natural accelerations of the rod are also observed with a long rod. The calculated results by considering the corrugation surface roughness as the external force almost agree with the experimental results. However, subharmonic, higher-subharmonic and differential and additional harmonic resonances do not occur so remarkably as those in experimental results.

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The frictional noise without lubrication is studied experimentally and theoretically, when a steel rod fixed at one end is pressed in the radial direction on a rotating thick disk with an angle of inclination. When the rod is inclined to the same direction of the rotation of the disk, rubbing and squeal noise occur and their frequencies become larger with an increase of the rod angle. The higher the mode is, the smaller the rate of increase of frequency is. The variations of the frequency with an increase of the rod angle were calculated by considering only the lateral vibration of the rod. There is a qualitative agreement with experimental results. When the rod is inclined to the reverse direction of the revolution of the disk, chatter noise of a high sound pressure level occurs.

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Using a power circulating gear testing machine, the influence of EP film properties on the anti-scoring performance was examined in air and nitrogen gas environments. An electron probe microanalyser and a transmission electron microscope are mainly used to determine the chemical composition and the structure of EP film on tooth surfaces. The findings are as follows : 1) In the case of sulphur-additive (dibenzyl-disulfide), EP film is much formed, and the chief compounds in EP film are FeS and FeS₂. FeS is observed more often in nitrogen gas environment than in an air one. 2) In the case of phosphorus-additive (dialkyl-phosphate), the compounds of Fe₃P and FePO₄ in EP film show a favorable effect for anti-scoring performance as well as the chemical polishing effects.

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This paper is intended to find out the best cutting condition for the purpose of improving the cutting efficiency of a spiral bevel gear and the roughness of its finished surface. But the cutting experiment by the gear generator requires too much trouble. Therefore the authors analysed conditions in which a single blade of the cutter cuts the spiral bevel gear, and clarified the cutting conditions of the single blade, with a view to simplifying the experiment by using a single blade instead of the cutter.

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In this paper, the interference between belt tooth and pulley tooth at the incomplete meshing region of toothed belt drives is numerically calculated by using the analytical method mentioned in the 4th report, and the influence of the radius of the tip corner rounding and the pressure angle of belt and pulley tooth on the interference is discussed. Also, the authors discuss experimentally on the effect of the radius of the tip corner rounding of pulley tooth on the fatigue strength of L type polyurethane and polychloroprene rubber belt, and the displacement of the belt pitch line depending on the load and the frictional force acting on belt tooth at the incomplete meshing region. Further, the sliding velocity of the contacting point of belt tooth and pulley tooth is calculated and the total nominal stress at the bottom land corner of belt tooth is discussed.

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Large gears or through-hardened and tempered gears are often put to practical use without any finishing subsequent to hobbing. It has been found that in these types of gears tooth surface roughness plays a decisive role in improving the loading capacity. In this research experiments were performed, considering, among the factors influencing the surface roughness, the effect of the builtup edge to be the most significant. Therefore, the BUEs resulting from various hobbing conditions are measured. Further, the cutting thickness is calculated theoretically for each case, as one of the factors influencing the formations of the BUEs. The interrelationship among the cutting thickness, the size of the BUEs, and the surface roughness has been found out, thus enabling a qualitative prediction of the surface roughness from the knowledge of the cutting thickness.

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