This paper brings together recent information on flow in curved pipes. As to fully developed laminar flow, the appearance of additional vortices for curved pipes of particular cross-sectional forms, existence of dual solutions, and effects of the pitch on the flow in a helically coiled pipe are presented. In the case of developing laminar flow in a curved pipe, fascinating behavior of the separation of the secondary flow boundary layer near the inner wall is shown. Flow in a rotating curved pipe and a periodically curved pipe are also discussed. Different hydrodynamic conditions at the inlet greatly affect the flow in the bend ; a strong swirl is created downstream of two 90° bends in combination according to the combination angles. A brief description of the discharge coefficients for bend flowmeters, and unsteady flow in curved pipes are also given.

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This paper presents an overview of the current trend of combustion research in spark-ignition engines. The subject of greatest and continuing interest is the elucidation of the mechanism of turbulent flame propagation and/or the flame structure. Although there remain some problems as yet, the goal may not necessarily be so far away, considering the remarkable progress in diagnostic techniques during the last decade. Advances in numerical aerodynamics have made it possible to simulate the flow phenomena in an engine. The field of numerical aero-thermo-chemistry, however, is still immature. Also, the investigation into knock has recently become a subject of growing interest. This review covers the above subjects, in some depth.

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The present paper if concerned with two transient thermal stress problems in a transversely isotropic infinite solid containing a crack with heat exchange on the crack surface. One is the problem of a penny-shaped crack, and the other is the problem of an external circular crack. It is very difficult to obtain the analytical solution for the temperature field, so only the finite difference method with respect to the time variable is introduced. Thermal stresses are analyzed by means of the transversely isotropic potential functions method. Numerical calculations were carried out for a graphite which belongs under transverse isotropy. The effects of transverse isotropy on the stress intensity factor are shown in the figures.

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In this paper, dynamic interaction phenomena on solid and liquid interfaces are discussed. Axisymmetrical responses of an infinite circular cylindrical shell, perfectly filled with liquid, are analyzed, based on Flugge's theory for a circular cylindrical shell and the potential theory for an ideal fluid under conditions of an impulsive external band pressure applied to the outer surface of the shell. The deflection and the moment of the shell and the pressure in the fluid are evaluated using a numerical inversion of the Laplace transformation method .the approximate solution for a shell with an equivalent mass on it is analyzed and is evaluated, based on the solution for the solid and liquid interactions.

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The shape rolling of an angle was analyzed by the energy method, in which the kinematically admissible velocity field was expressed as the sum of the fundamental velocity fields, and finite element division was applied, as reported in the previous paper. Here, most fundamental velocity fields are determined by a method similar to that proposed already, though some special velocity fields are defined concerning the position of a material before rolling and the curling of a material after rolling. Rolling properties are obtained and some discussions are made from a mechanical standpoint. Curling depends on the difference of the circumferencial velocities of the upper and lower rolls, and distortion of the cross section of a material is caused by the reduction of the side parts of a material near the upper and lower rolls. Consequently, it is proved that the authors' energy method can be applied to shape rolling successfully.

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To clarify the stochastic (random) behavior of cavitation in the near-sub-cavitating range, we statistically analyzed the acoustic pressure pulses generated from cavitation, and discussed subcavitation by introducing the threshold level selected for pulse detection for various states of test water, as well as the behavior of cavitation bubbles. We found : (i) the stochastic behavior is remarkably observed for a selected higher threshold level, and (ii) after the bubble cloud is initiated, the pulse energy directly related to eroslon deviates from the n-th power of cavitation number, σ, and decreases rapidly with σ.

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The P_LT_N method was extended to solve the equation of transfer in a plane-parallel, homogeneous scattering medium bounded by two transparent solid plates. From the results of extensive test computations performed for Rayleigh and Henyey-Greenstein phase functions, it was found that the present method can be used stably and accurately to solve the equation of transfer for a scattering medium with transparent solid boundaries, even for an optically thick case ; and that the accuracy of computations is notably improved by increasing the order of Chebyshev polynomials in the expansion.

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This paper reports on a comparison of the experimental and analytical results of the 1/3-harmonic and parametric combination resonance of a roller chain stretched vertically, which is regarded as a system with many degrees of freedom when the elongation of the chain during vibration is taken into account. A representative frictional coefficient is determined, and the influence of the phase angle between the forced displacement and the prescribed tension fluctuation on the combination resonance are examined using a chain with comparatively large friction. A comparison between characteristics of the combination resonances and the 1/3-harmonic vibration is also made. A good agreement between experimental and analytical results was confirmed.

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In order to calculate the pressure pulsations in pipelines in a frequency domain, it is necessary to linearize the velocity-squared nonlinear damping, under the condition that the flow in the pipe is periodic, but not sinusoidal. The authors have proposed a theory for the equivalent linearization in such cases, where two coefficients should be determined : one for the steady-state component of the flow in the pipe and the other for the fluctuating component including all frequency components. To verify the applicability of the theory, the responses of pressure pulsations in a straight pipe were calculated for several known input flows by the transfer matrix method, using three linearization schemes based n this theory. The results were all in good agreement with those calculated by the Runge-Kutta-Gill integration method.

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When a hanging articulated pipe is vertically excited at random in water, the dynamic behavior of the pipe is analyzed as a dynamic problem of a system with random parametric excitation and nonlinear damping. Though this system may become unstable under certain input conditions, the response does not diverge, due to the fluid drag force in proportion to the squared velocity. In this study, the response under the instability condition was analyzed. A model experiment was also carried out to confirm the analytical model. As a result, a simple equation between the input and the response was derived, and was confirmed by the model experiment. It was seen that this simple equation is valid for a small input, and the root mean square of the response velocity is proportional to the power spectral density of the parametric excitation at twice the natural frequency of the excelling mode.

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Vibration and attitude control problems are dealt with for a suspended maneuvering module (SMM), in which a gondola with control functions on board is suspended by a rope from above. Keeping in mind the applications of this type of suspended system for rescue work in the csse of fires in skyscrapers, it is necessary to control the position of the SMM toward the targets and to suppress the vibration of both the gondola and the rope. A visual feedback control system made of a TV camera and a PSD (Position Sensitive Detector) image information system are employed in this study in order to obtain the correct orientstion toward the target automstically and to search out the targets in vibrational environments. Some useful techniques using such feedback systems are demonstrated for estimating the relative positions between the SMM and the target in static states and even during vibration. Also, a vibration control method is proposed that controls air jets by the on-off PWM (Pulse Width Modulation) manner.

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The objective of this study is to establish an analytical procedure for viscoelastic fluid film lubrication based on a nonlinear four-element model, which should apply to lubricating oils containing a large quantity of high molecular-weight polymers. It is made clear from the flow characteristic test that the viscoelastic behavior of such lubricants is represented by a rheology equation based on a four-element model which consists of two nonlinear dashpots and two nonlinear springs. A modified Reynolds equation for finite-width bearings is derived by employing the nonlinear rheology equation. The effects of nonlinear viscoelastic characteristics on the film pressure are then studied with a parallel circular squeeze bearing, and it is shown that the experimental results agree well with the theoretical predictions.

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This paper describes an optimum design of hydrodynamic journal bearings under laminar and turbulent operating conditions. Simplified closed-form design formulas are presented for the eccentricity ratio, friction force on the journal surface and whirl onset velocity as a function of the Sommerfeld number or eccentricity ratio. The radial clearance, slenderness ratio and viscosity of oil, which optimize both the oil flow rate and the oil film temperature rise in hydrodynamic journal bearings under a constant load, are determined numerically for a wide range of journal revolution speeds.

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The floating clearance between the floating head sliders and disks of large capacity magnetic disk files is getting smaller and smaller, with the present values ranging form 0.3 to 0.5 μm. To ensure reliability, dynamic characteristics of sliders subjected to disk oscillation or runout munt be accurately predicted. Finite difference methods or the divergence formulation methods have, to the present, been used to obtain dynamic characteristics of sliders, but difficulties have arisen in treating complex-shaped sliders. In this paper, the finite element method is used to solve these difficulties. The calculated results agree with those obtained by the above-mentioned conventional methods. They also agree with the experimental results obtained using a flat taper-type slider with a yaw angle. Furthermore, the dynamic characteristics of a grooved slider and a negative pressure induction slider have been predicted by this calculation method .The present method is formulated to include the calculations of both static and dynamic characteristics.

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This paper reports on a study on the root stress of a thin-rimmed internal spur gear supported with pins. Root stress analyses by the finite element method (FEM) for internal spur gears of various rim thicknesses supported with pins were carried out. The effects of constraint conditions for gear models on the root stresses and the deformation of the rim are discussed, and the relations between the root stresses, the deformation of the rim and the position of the loaded teeth are indicated. The effects of the number of pins and the rim thickness on the root stresses are clarified to a considerable extent.

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Recent developments in the electronics industry require a piercing technique for making fine holes at a high production rate. The present research attempts to apply to such piercing a new manufacturing process utilizing the impact compression of a viscoplastic pressure medium recently proposed by the authors. As a result, the process is shown to be successful in piercing various fine holes, unobtainable by the conventional shearing process : for example, circular holes of 0.05 mm and 0.1 mm in diameter and a slit of 0.05 mm in width. The piercing pressure is examined theoretically and experimentally.

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Cutting forces and deflections of a workpiece are measured from the start of cutting operations and one of the important physical causes of regenerative chatter is found to be a small change of the cutting force that necessarily exists, even in a stable cutting condition. In a stable cutting condition, the workpiece is slightly disturbed by a hammer blow, and the changes of the cutting forces and the workpiece deflections are simultaneously measured. Vibratory parameters of a workpiece, that is, spring constant, damping coefficient and so on are precisely measured, and more suitable equations of motion for chatter vibration are proposed. These proposed differential equations of motion are calculated by a digital computer for two initial conditions : first, the workpiece suffers a small disturbance of displacement ; second, the workpiece is disturbed by a hammer blow. Results of numerical calculations are compared with experimental results, and a good quantitative coincidence is derived.

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A new sensor to detect stress and temperature in plastic deformation processes has been developed. Installed in a die, this sensor can detect both pressure and frictional stresses acting on the same point of the die surface. Moreover, it can simultaneously detect surface temperature. The sensor is designed to detect pressure from 0 to 300 MPa and frictional stresses from 0 to 150 MPa. The principle of detecting 3-directional stress is that for the deformation of a parallel plate structure. Surface temperature is calculated from the two temperatures detected by two pairs of thermocouples at different points under the surface. The sensor is called a Die-sensor. Examples of measurements are shown, and applications of the sensor are discussed.

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