An elastic-plastic analysis of notched plates subjected to tension force or bending moment was made. Based on this analysis, methods of evaluating approximately the stress and strain at the notch root were proposed. Dimensionless master curves were proposed for estimating the stress and strain concentration factors under small-scale yielding condition and the stress and strain at the notch root under large-scale yielding condition. This master-curve approach was found valid in all the cases analysed in this study. A simple formula was further developed by which the stress and strain at the notch root could approximately be calculated under load conditions below and above the gross yield stress by using the J-integral, together with a formula for estimating the J-integral. The estimated values of the notch stress and strain by this set of the approximation formulae agreed well with the results of numerical analysis.

View full abstract

The contact problem of two laminated dissimilar rectangular plates subjected to an arbitrary symmetric loading is considered. The two dimensional theory of elasticity is used to analyse the contact stress and the deformation between the rectangular plates. By neglecting shearing stress on the contact surface, an exact solution satisfying the remaining boundary conditions is obtained. Numerical calculations are carried out for various rigidities and thicknesses of the plates under various loading conditions. In order to examine the results of the theoretical analysis, the contact stress is measured experimentally by using pressure-sensitive pins attached to a rectangular plate. It is confirmed that the theoretical results agree well with the experimental ones.

View full abstract

In the framework of the theory of continua with kinematical constraint of inextensibility, bifurcation from homogeneous finite deformation of an obliquely fiber-reinforced elastic slab under axial loads, both tensile and compressive, is studied. The matrix is assumed to be Blatz-Ko foam rubber. In spite of the uniform axial stress loading, the initial homogeneous deformation consists not only of axial extension or contraction but also of pure shear deformation owing to the oblique reinforcement. The bifurcation is analyzed on the basis of the incremental deformation theory. For various wavelength-to-thickness ratios, the critical loads are shown in the form of curves as a function of fiber inclination.

View full abstract

We devised a method of calculating the optimum angular pitches for blades in a high-speed fan that has unequal angular pitches, in order to reduce the level of a tonal annoying noise in such a fan. We used the influence coefficient-and least-squares methods in iterative calculations in which the harmonic spectrum associated with the angular blade pitches was made to converge to a target harmonic spectrum. Our new method of calculation makes it possible to determine the optimum angular blade pitches and target harmonic spectrum necessary for the production of a quiet fan.

View full abstract

The mean velocity field of a turbulent wake behind a cruciform circular cylinder which is composed of two sufficiently long circular cylinders is examined experimentally. The measurements were performed for the surface pressure distributions on the cruciform circular cylinder and the mean velocity profiles in the wake at a number of downstream stations in a wide range of x/d=3 to 594. It is revealed that the decay rate of centerline velocity defect is considerably slower, while the rate of growth of the half-width for the y=z plane of the present wake is very close to that of a two-dimensional wake. In the center region of the wake of the cruciform shape, secondary flows are observed and the magnitude of the flow is measured. The drag coefficient of the cruciform circular cylinder almost agrees with that of the equivalent two-dimensional circular cylinder.

View full abstract

This paper presents analysing methods of the response characteristics necessary for designing a miniature pressure detector of capacitance type and electronic methods for realizing a sensitive and wide-band measurement of pressure. Several detectors, a transducer and an amplifier are prepared with the object of examining the adaptability and practicality of these methods. Dynamic measurement and static comparative test between the present device and the other high-sensitive pressure measuring methods show that the analysis can well express the detector response to pressure and that the present method enables measurements more sensitive than the resolution of 0.002 mmAq (0.02 Pa).

View full abstract

Characteristics of fluid thrust acting on valve stem are studied by experiment in close relation to flow patterns of a supersonic air flow expanding through a valve of simplified geometries. The valve consists of a conical plug and a plane seat, and is mounted at a nozzle exit of a blow-down facility. The experimental pressure ratio is up to twenty. Changes of fluid thrust are closely related to transition of flow patterns. As the pressure ratio increases, the flow which, separated due to shock-boundary layer interaction, reattaches to plug surface, is abruptly altered into a flow pattern where the separation opens into atmosphere, and at the same time the fluid thrust increases significantly. From the measured pressure distributions along plug surface, it is clear that this change of fluid thrust is mainly caused by the reattached separation with negative pressure opening into atmosphere. This transition of flow patterns is simulated by a numerical analysis.

View full abstract

When a thin liquid layer, which is at rest under the action or gravity on a horizontal wall, is locally heated from below, a flow is induced in the layer by the surface-tension force. The flow in such a case is studied theoretically by using the Stokes approximation and the thin film approximation. This flow is governed by two dimensionless parameters, Nusselt number N and thermal Weber number M. When the liquid layer is heated from below, the free surface is always depressed. When the heating is strong, the liquid layer breaks up. The critical value of the thermal Weber number, above which the liquid layer breaks up, is found as a function of N. The shapes of the surface just when a breakup occurs are calculated. The critical thermal Weber numbers are experimentally found for the case of an oil sheet. These values are in agreement with the predictions from the theory.

View full abstract

The absolute velocities and static pressures in a standard type vortex pump were measured with five-hole pitot tubes for clarifying the flow conditions in the pump. The results can be summarized as follows : The flow through the impeller increased with an increase in discharge and the rate of increase was high in the over-discharge range. The boundary radius of the impeller inlet and outlet regions and the peripheral component of the velocity at the inlet decreased as the discharge increased. Furthermore, a theoretical investigation was made to clarify the internal flow conditions. The flow pattern theoretically obtained consists of a through-flow and a circulation flow, showing good agreement with the measured results.

View full abstract

The internal flow conditions were investigated experimentally and theoretically in the first report. In this report the internal flow conditions were measured over a wide range of impeller shapes and the pump performance was analyzed using the flow pattern which was clarified in the first report. The following results were obtained from this investigation. The theoretical no-slip pump head slightly decreased with an increase in discharge owing to a decrease in mean impeller outlet radius of the through-flow. Hydraulic loss increased as the discharge increased, but power loss from the circulating flow remained constant. Due to this power loss, the efficiency of the vortex pump was lower than that of a standard centrifugal pump. Variations of theoretical pump head, losses and other items affected by impeller shape were discussed and reasons for the differences in performance due to impeller shape were made clear.

View full abstract

Thermal structure of a flat plate turbulent boundary layer diffusion flame has been investigated experimentally. Measurements of fluctuating temperature and fluctuating velocity have been made, using an electrically compensated fine wire thermocouple and a laser-Doppler velocimeter respectively. Results show that a profile of turbulent intensity of temperature fluctuation has two maxima and one minimum. The minimum is located at the station where the gradient of mean temperature is zero. On the other hand, gradients of mean temperature at stations of two maxima are very high. In the region between the flat plate and the flame, the thermal structure is characterized by low frequency fluctuations, which are mainly attributed to fluctuations of the reaction rate at the reaction zone. In the region between the flame and the edge of the thermal boundary layer, the thermal structure is characterized by high amplitude and high frequency temperature fluctuations, which are mainly caused by the mixing of hot and cold gases.

View full abstract

Calculations using a chemical kinetic model for the oxidation process of unburned methanol were carried out on exhaust gases from a methanol fueled S.I. engine at air-fuel equivalence ratios of 0.8, 1.0, 1.2, and 1.4. Good correlation between the calculated and experimental results were obtained for methanol reaction behavior as well as formaldehyde concentration profile. The conversion reaction of nitric oxide to nitrogen dioxide plays a significant role in the oxidation of unburned methanol and the formation of formaldehyde. The presence of molecular oxygen in exhaust gases has a favorable effect on this conversion. However rich the oxygen may be, methanol oxidation is extremely slow in the absence of nitric oxide. With rich oxygen, methanol oxidation is rapid due to an increasing nitric oxide. It is explained by considering those effects how the methanol reaction rate attains a maximum value in exhaust gases between airfuel equivalence ratios of 1.0 and 1.2.

View full abstract

For vibration analysis of a rotor-bearing system considering gyroscopic effect and large damping forces due to bearings, a new analytical method to handle various boundary condition has been applied. It can be called a quasi-modal transformation method developed from the modal transformation. A complex eigenvalue solution method based upon the quasi-modal transformation is described and the results of corresponding numerical examples indicate that the solution has a sufficient accuracy. The quasi-modal method is also applied to the response history analysis in nonlinear rotor dynamics. The method is most suitable and powerful for vibration analysis considering nonlinear boundaries. In this analysis a new numerical integration method is introduced. It may be called a hybrid integration which combines the conventional direct integration and the modal one. The numerical examples show that the hybrid integration is numerically stable and practical.

View full abstract

In this paper, the vibrations of circular plates with variable thickness are studied by the method of Mindlin's thick plate theory. In author's previous report, the vibrations of non-hole circular plates have been analyzed exactly and in this paper, an exact solution of circular plates with hole is obtained. The effects of some parameters on frequencies are discussed and the present theory is compared with the classical theory.

View full abstract

This report deals with a method of evaluating coupled natural frequencies of a circular cylindrical tank. Starting from a variational principle, the authors obtain a functional relating to coupled oscillations between a linear elastic body of infinitesimal deformations and a perfect fluid of small wave heights. By imposing as constraints several of stationary conditions of the functional above-mentioned, an alternate functional is derived from which a complementary Rayleigh quotient is obtained. The first approximation for the complementary Rayleigh quotient gives approximate formulas of coupled natural frequencies for a circular cylindrical tank oscillating in an axisymmetric manner. Numerical examples show satisfactory coincidence between exact natural frequencies and approximate ones in the case of sloshing modes, whereas tolerable error of the approximation in the case of lower bulging modes.

View full abstract

For smoothing the motion of a robot hand, a simple method for trajectory interpolation of the robot hand has been developed, in which successive straight line trajectories are connected continuously by parabolas. Only a linear interpolation function of computation is required for this method and it makes the computation time so short that the trajectory interpolation can be performed real time while the robot is in motion. Determination of a closed loop spatial mechanism with single mobility which is equivalent to the robot arm with a specified hand location is also described in the paper for the purpose of analyzing joint displacements of the robot arm.

View full abstract

In this paper the authors investigated the effects of web arrangements on vibration of welded structure gears. The circumferential, radial and axial vibration accelerations of various types of welded gears were measured under different running conditions. The vibration accelerations of welded gears increase generally with an increase in the rigidity of web and rim parts of the gears. A double web gear shows the largest values of vibration accelerations and an asymmetric type of a welded gear the smallest ones due to the effects of the axial force, which is produced by a deformation of the rim and the web parts of the welded gear. The conversion rate of the circumferential vibration into a radial or axial one is different according to the type of the web arrangement.

View full abstract

In the machining of metals, it has been believed that the smoother the rake and the flank face on tooth are, the smaller the tool wear is and the longer the tool life is. Therefore such tools as hobs, demanding high accuracy, are ground carefully. But the degree and the cause of the influence which the face roughness of tooth has upon tool wear are not made clear completely. In this paper, relations between the hob tooth roughness and the tooth wear are made sufficiently clear concerning the degree and the cause of the influence, through many fundamental cutting tests.

View full abstract

The static bending stiffness and the axial displacement of the 7/24 taper shank tool, which is used in the machining center, have been experimentally investigated. Mainly, the effects of the taper size and angle error were investigated, by changing the tensile force of a draw-in bolt. From the results, It was found that the bending stiffness is affected by the tensile force and the taper angle error. The axial displacements of the taper shank are affected by the taper angle error, but independent of the taper size. In addition, the similarity law of the static bending stiffness is precisely investigated. From the results, it was found that the inclination angle which is the most important factor is in inverse proportion to the second power of the scale factor.

View full abstract

In this paper, the characteristics of a treatment of the grinding wheel (sulphur filled and nickel plated) has been examined in a creep feed grinding. It was found that the grinding forces always become smaller in a treated grinding wheel than in a normal grinding wheel and a critical depth of cut of which workpiece burning occurs, is large in the treated grinding wheel. Also, in comparison of the grinding wear and the grinding temperature, the Ni plated grinding wheel has smaller values than the normal grinding. Although the distribution of temperatures in the workpiece with normal grinding wheel concentrates in a small portion on contacting area, that of Ni plated grinding wheel does not show a steep temperature rise.

View full abstract