In spite of the practical importance, the solutions for the title problem under the action of various loadings have not been obtained. In this paper, based on the classical theory, and changing the geometry of plate, the following three cases are treated. The plate is bent under the action of (a) the vertical force by the column, (b) the moment by the column, and (c) a uniformly distributed load respectively. The construction of solution is based on the principle of superposition. The boundary conditions are satisfied by the Lekhnitski-Muskhelishvili's method on the internal contour and by the point matching method on the external. The following conclusions are obtained. (1) The point matching method is sufficiently effective. (2) Using the values nondimensionalized with respect to a side length of the square, the influence of the geometry on the stress concentration is the largest in (c) and the smallest in (b), and so on.

View full abstract

In order to investigate how mechanical and temperature conditions influence low cycle fatigue fracture, it is necessary to give attention to the process of fatigue fracture. The behaviour of fatigue cracks was observed in order to clarify the process of fatigue fracture. Fatigue tests were carried out using a AISI 321 stainless steel by a push-pull testing machine. According to the present experimental results, it is clarified that when fatigue tests are carried out under the same plastic strain range but different temperature conditions, the similar state of cracks are observed, provided the same ratio of number of repeated cycles to the number of cycles to fracture is given. Thus, it is concluded that the process of the low cycle fatigue fracture are influenced mainly by the plastic strain range, and that the rate of fatigue fracture depends on temperature.

View full abstract

In this paper an elastic analysis of the expansion joints used in pressure vessels and pipe lines under axial load is presented. Although these joints are widely used, few investigations on their strength have been published and at present designers are employing the rough formulas of M. W. Kellogg Co. for practical designing. Therefore in this investigation this problem is treated by using a shell theory and a calculating method is established by which the stresses and deformation of these joints can be evaluated. Numerical results of stress distributions and deformation for some dimensions of the expansion joints are shown, and these results are compared with experimental ones.

View full abstract

There is the Green's function or the Neumann's one as the fundamental solution of a ther-moelastic problem for an elastic body whose surface temperature or surface heat flow is given by a function of time and position. Each function for a semi-infinite body with a surface heat source has been introduced. When the body surface is exposed to a medium whose temperature varies throughout the space and with the time, however, the fundamental solution of thermoelasticity, which is the Robin's function, has not been investigated though the solution covers even the Green's and the Neumann's Then the author introduces the Robin's function. In other words, when the surface of the body, which has initially zero temperature, is exposed to a medium with zero temperature, and an instantaneous heat source generates on its surface, the temperature field and thermal stress distributions are analysed. Thereafter the variations of temperature and thermal stresses with time are numarically shown.

View full abstract

In this report, methods to restrain stick-slip in a hydraulic driving system are described. The acceleration feedback method is theoretically and experimentally verified to be very effective for the restriction of stick-slip. In addition, the transient velocity feedback method is found as effective as the acceleration feedback and more practical with respect to the drift in an electronic detecting device. In this method, the voltage in proportion to the table velocity is differentiated by a first order lead network and fed back to the servo amplifier. Furthermore, it is shown that self-excited oscillation may take place when the above mentioned feedback compensation is effected, but that this oscillation can be diminished by imposing dither on the servovalve.

View full abstract

In this paper, at first the authors analyze the dynamic characteristics of the self-damped air spring on the basis of the linear theory from the standpoint of the design of air suspension bogies. The equivalent mechanical model of the self-damped air spring is obtained, which is a kind of socalled elastically supported damper systems, and the relationship among the elements of the model and the design parameters of the air spring are given. Then, using the mechanical model, both natural vibration and transient response of the air suspension bogie are analyzed numerically. As the result, it is shown that the natural frequency and the damping ratio of the self-damped air suspension bogie scarcely vary with the car body weight, and the self-damped air suspension can reduce the magnitude of the transient response compared with a conventional mechanical suspension with oil-dampers.

View full abstract

A pseudo-shock occurs, when a supersonic flow is decelerated to subsonic in a duct surrounded by walls. Its shape is influenced by the main stream Mach number and the condition of the boundary layer. In this study, the authors investigated the phenomena of the λ-type pseudo-shocks experimentally, and obtained the distribution of the static and total pressure in the duct in the pseudo-shock region. The results show that the mechanism of the pseudo-shock can be divided into two parts ; the first is the upstream region in which the supersonic flow is gradually decelerated to sonic, and in the second downstream region the high speed flow in the central core is mixed with the low speed flow near the walls.

View full abstract

We measured the pressure distribution around eccentric rotating cylinders, of which the outer cylinder rotates, covering a wide range from a laminar flow to a fully developed turbulent flow in the case of various eccentricity ratios and clearance ratios. Water and glycerine-water solutions are used as working fluids, and pressure measurements are done under the condition that fluid pressure is increased in order to prevent the occurrence of cavitation. And we investigated experimentally the effects of eccentricity ratio and clearance ratio on pressure distribution and forceacting on the inner cylinder. The results obtained are as follows. (1) In the case where clearance ratio is relatively small, the theoretical pressure distribution ehich we reported previously is in good agreement with the measured one in a laminar flow region. (2) In a turbulent flow region, negative pressure occupies the greater part of clearance between the eccentric rotating cylinders. (3) An unstable flow between eccentric rotating cylinders was observed for certain clearance ratios β (β=0.04414 and 0.09413) in a transient region.

View full abstract

There are many essentially different flow types between the disk rotating in an open environment and the one with a shroud. In the present paper, we aim to research the heat and mass transfer rates from the rotating disk confronting to a stationary disk. Two patterns in variation of Sherwood number are formed with diminution of opening space c. The one of patterns is that Sherwood number decreases with the ratio of c/d₀, and the other changes as Sherwood number decreases to the minimum value at c/d₀=0.022 and turns to increase, where d₀ is the diameter of the rotating disk. In addition, we notice that the similarities between Sherwood and Nusselt numbers realize for each pattern, and that the rates of heat and mass transfer K_cm/α_m is estimated to be 1.35. In regard to j-factor by Colburn we affirm j_H is almost equivalent to J_D.

View full abstract

An investigation on the mass transfer for a two-dimensional jet of air impinging normally on a flat plate was undertaken. Results are summarized as follows. (1) Sherwood numbers at the stagnation point obtained experimentally are about twice those predicted by theory. This fact is due to the turbulence of jet itself. (2) By assuming the flow field on a plate simulated by the wall jet having an imaginary slot at the stagnation point and by applying Myer's theory concerning the heat transfer of the wall jet, we obtained the theoretical prediction for local Sherwood numbersm which agree well with experimental data. (3) Gardon's postulate that mean Sherwood number is correlated by the arrival Reynolds number was checked by the present experiment and discussed under the theoretical background.

View full abstract

Experimental and theoretical studies were made upon the configuration and detaching behaviors of an isolated vapor bubble in saturated nucleate boiling of water and ethanol. The dynamic contact angle was found to vary sharply as the bubble grows, so it should be concluded that the concept of contact angle can't be directly applied to the discussion of boiling heat transfer. The boiling rate at an individual nucleation site, namely D_df was predicted to be dependent upon heat flux and good agreement was obtained with experimental results. Further, many other data were newly obtained concerning the bubble shape and detaching characteristics.

View full abstract

There are a few formulas for the cavity-type mufflers aimed to reduce the noise radiating form an open end to free space. In this paper, the authors have attempted to establish more precise formulas for the attenuation of such mufflers. The attampt has been completed with success and it is now shown that those formulas given in the articles on mufflers can all be derived from the general equations given in this paper.

View full abstract

This paper deals with the problems in the sampling procedure of smoke density measurement concerning the regularity of smoke content in sample gas taken under constant engine operating conditions. Experimental results obtained on a two-stroke single cylinder diesel engine confirm that the Bosch smoke density varies with the sampling position along the exhaust pipe. Data are given on a smoke content-time variation in the exhaust pipe measured directly with a light absorption smokemeter as well as a pressure variation and discussion is presented about the influence of the phase correlation among the smoke content, pressure, and flow velocity variations on the smoke density of the sample gas. The phase correlation of the smoke content variation with pulsational flow is shown to be a predominant factor affecting the amount of smoke in sample gas. It is concluded that well-mixed gas would have to be sampled for the accurate measurement.

View full abstract

Die Heftigkeit des Klopfens oder harten Gangs bei einer Verbrennungskraftmaschine wird seit Jahrzehnten durch den Druckanstieg je Kurbelwinkel bezeichnet, obwohl der Grund dafur bis heute noch nicht ganz klar geworden ist. Die Verfasser haben die Beziehungen zwischen Druckanstieg und stoВariger Beanspruchung am Triebwerk bzw. Betriebsgerausch theoretisch betrachtet. Zur Bestatigung der Gultigkeit der angestellten Voraussetzungen wurden auch Experimente durchgefuhrt, und die theoretischen Ergebnisse wurden mit den MeВwerten verglichen, wodurch die Bedeutung des Druckanstieges je Kurbelwinkel klarer geworden ist.

View full abstract

Analysis of valve motion would reduce a great deal of experimental work preceding the final decision of valve gear design. A lot of attempts for such analysis have not been quite successful with their poor experimental data to be compared with the calculated results, which in due course mada authors take great care for such measurements at the beginning of the study. In this report authors introduced their methods of measurements for such use and discussed a single mass system (serial system composed of cam-equivalent push rod-equivalent valve mass-valve spring) for the description of valve motion. New definition of single mass system has enabled authors to give elegant explanation of various dynamic behaviors which characterize actual systems. This new equivalent system was applied to the calculation of valve motions, which were closely compared with the experimental results mentioned above.

View full abstract

A study was made of surface roughness effects on dry friction between two metals, assuming that the asperities are cones of slopes which depend on the surface roughness. Theoretical expressions were derived for ploughing, adhesion and total friction coefficients of cones, spheres and aquare pyramids ploughing along the soft metal surface. A comparison of calculated values based on this theory with experimental data shows good agreement. Moreover, theoretical discussion was made of surface roughness effects on dry friction on the basis of the analysis of mechanism of abrasive friction. The theoretical estimation of the coefficient of friction between two metal surfaces can be carried out using the relations between the surface roughness and the slope of the asperities, and the coefficient of friction due to the adhesion at the interface. The experiments also showed that the maximum displacement between two metal surfaces in contact before gross sliding occurs, increases with an increase of the surface roughness.

View full abstract

It is common experience that nuts and other threaded fasteners can be loosened by vibration or by impact even though they are initially tight. This report proves that a threaded fastener is hard to loosen when the angle of thread and the measurement of the screw end are properly chosen. The fastener with 60 deg. V thread is easy to loosen. Because the compressive stress waves, being propagated from the pressure falnk, are reflected at the free end of the screw, when they change into tensile stress waves, and they return to the pressure flank on the bolt side only. So a threaded fastener becomes hard to loosen, when the tensile stress waves don't return to the pressure falnk of the bolt thread. On the following two occasions, the tensile stress waves don't return to the pressure flank. (1) When the tensile stress waves are propagated towards the unthreaded part of the bolt. (2) When they are reflected back to the pressure falnk being changed into compressive stress weves.

View full abstract

A study was carried out on the mechanis, of oil loss past a piston ring series on account of its oil scraping ability. It was made clear that (1) oil scraping ability of the ring series was not given as the sum of each ring's ability and was attected by the mutual arrangement of rings in the series, (2) oil loss past the ring series was divided into two different parts : the one being a hydrodynamic loss nad the other a loss caused by the gas flow through the ring series, (3) the longer the length of the piston top land and the smaller the clearance between the piston and the cylinder wall was, the more effectively the oil loss was decreased, (4) to decrease the oil loss which was caused by the gas flow, oil scraping ability of the 2nd ring was much more important than that of top ring.

View full abstract

On an actual machine tool slideway, the "stick slip" motion of moving element is investigated experimentally under various sliding conditions, that is a variety of applied lubricant, mass of moving element, stiffness of driving system and driving speed, and the fundamental characteristis of the "stick slip" motion are clarified. Basing on these experimental results, in order to make the "stick slip" process clear, the characteristics of static friction in the period of "stick" are first studied concretely. As a result, it has been shown that the static frictional coefficient generally increases with increasing "stick" time, and that it can be expressed with a simple exponential formula by the "stick" time. Then, the transitional behavior of boundary lubricated mecahnism in slideway in the "stick" period is discussed in detail basing on the experimental results.

View full abstract

The properties of the "stick slip" motion occuring in the machine tool slideway are closely connected with the characteristics both in static and kinetic friction. In a previous paper, the static friction in the "stick" period was investigated. It has been shown in this paper that the characteristics of kinetic friction in the "slip" period can be examined collectively using the mean kinetic frictional coefficient μ_m in this period, and that the main factors which affect μ_m are the static frictional coefficient at the beginning of the "slip" motion and the time of the "slip" period. As a result, an expression for μ_m is proposed. Then, basing on the expressions for static and kinetic friction, the boundary conditions for occurrence of the "stick slip" motion are clarified, and the relation between properties of the "stick slip" motion and frictional characteristics is examined quantitatively.

View full abstract

The orthogonal cutting of cast iron was investigated in respect to the formation process of discontinuous chips. Four types of discontinuous chip ; shear type, tear type with a small crack, tear type with a large crack and crack type ware recognized in the micro-photographs of chip formation process taken by a motor-driven 35mm camera with a micro-flash illumination. From enlarged profile of surface irregularity taken by a surface roughness meter under various cutting conditions, the number of cracks and the angle of cracked fracture to the cutting direction were measured. As a result, it is understood that the type of chip produced depends on the cutting speed and the depth of cut, but not the tool rake angle.

View full abstract

This paper is concerned with a theoretical analysis of the dynamic plastic deformation of thin cylindrical shells under internal impulsive pressure. The shells are assumed to be made of a perfectly-plastic rigid material that obeys the flow rule of von Mises. The dynamic pressure is suposed to be such that at some given time a uniform radial velocity is instantaneously imparted to the entire shell wall lying between the reinforcing rings. It is possible to set up certain equations of motion on the basis of a few assumptions concerning stress-strain relation. Under certain conditions the expressions for principal stresses, radial velocity and displacement of the shell wall, deformation time and bending wave velocity are obtained in simple closed forms. The profiles of deformed shell are specified in three different types depending upon the distance between rings.

View full abstract

This paper is concerned with an experimental investigation of plastic deformation of thin cylindrical shells under an internal impulsive pressure. The analytical [results developed in the 1st report are examined by the experiments in deformation of copper shells. By using a technique of exploding wires an axially uniform and symmetrical pressure pulse is generated which propagates radially through the water within the shell. In cases where the pressure pulse strikes the inner surface of shell wall must be taken into account the reflected pressure pulse due to the mismatch of the mass of shell with the mass of pressure pulse in water. In order to satisfy] the presuppositions used in the previous analyses, it is necessary that the magnitude of the reflected pressure pulse be made sufficiently small in comparison with that of the pressure pulse. The influences of the mass of shells on the reflected pressure pulse are discussed. The displacements of the shell walls are observed with an accuracy of the order of 10μsec by using an electronic camera. Reasonable agreements between the experimental results and the analytical results are obtained except near the reinforcing rings in the early stage of deformation.

View full abstract