Showing papers in "Jsme International Journal Series B-fluids and Thermal Engineering in 1978"
TL;DR: In this article, two tandem circular cylinders in a stream up to the range of much higher Reynolds numbers than the critical one were investigated in a low speed wind tunnel, by making the surface of the upstream cylinder rough with two types of surface roughness, the critical Reynolds number of the cylinders was reduced.
Abstract: Flows around two tandem circular cylinders in a stream up to the range of much higher Reynolds numbers than the critical one were investigated in a low speed wind tunnel. By making the surface of the upstream circular cylinder rough with two types of surface roughness, the critical Reynolds number of the cylinders was reduced. Drag coefficients and Strouhal numbers of the two tandem circular cylinders were measured and the flow patterns on the cylinders were visualized by the surface oil-flow technique, in the subcritical flow regime, in the supercritical one where there were laminar bubbles followed by turbulent separation and in the transcritical one where purely turbulent separation occurred without laminar bubbles but with an extremely regular vortex shedding behind the cylinders. The flow characteristics of the two tandem circular cylinders were discussed and the effects of Reynolds numbers and the gap spacing between the two cylinders were made clear.
80 citations
TL;DR: In this article, the authors deal with the mechanism of an impulsive pressure generated by a collapsing bubble in a water filled shock tube and apply an expansion wave and a subsequent compression wave to single, twin and triadic bubbles.
Abstract: This paper deals experimentally with the mechanism of an impulsive pressure generated by a collapsing bubble. In a water filled shock tube, an expansion wave and a subsequent compression wave are applied to single, twin and triadic bubbles. The growth, collapse and rebound of bubbles situated at various distances from a solid boundary are observed by means of high-speed photography and in-line Fraunhofer holography using a pulsed dye laser. The results indicate that the impulsive pressure is caused by a shock wave radiated at the instant of the rebound of a collapsing bubble, and that the subsequent jet impingement does not produce any detectable effects. The pressure pulse is found to be of the order 104 ∼ 105 atm, and its duration 2 ∼ 3 μsec.
60 citations
TL;DR: In this article, the influence of the thickness of a ring gear on the fillet stress of the ring gear and the load distribution among each planet gear was studied experimentally in a single-stage Stoeckicht planetary gear (Type 2K-H) constructed with spur gears.
Abstract: The authors studied experimentally the influences of the thickness of a ring gear on the fillet stress of the ring gear and the load distribution among each planet gear. The planetary gear used in this study is a single-stage Stoeckicht planetary gear (Type 2K-H) constructed with spur gears. The results are as follows : (i) The fillet stress of the tension side in the ring gear of a toothed thin-ring is smaller than that in the ring gear of a toothed thick-ring. But the fillet stress of the compression side in the former is larger than that in the latter. (ii) The influence of the eccentricity of the ring gear is sufficiently eliminated by using a ring gear floated with gear coupling, independently of the thickness of the ring gear. And the mean load distribution rates for each planet gear are nearly equal.
48 citations
TL;DR: In this paper, a theoretical analysis was made on the blot loosening mechanism on transversely loaded joints whose clamped parts slip relatively and the following were derived: (1) the condition necessary for the bolts to loosen by self rotation, (2) the physical meaning and the theoretical equation of the critical slippage between the clamped part, (below which the bolts do not rotate), (3) the theoretical equations of the bolt loosening angle under the above-mentioned condition.
Abstract: A theoretical analysis was made on the blot loosening mechanism on transversely loaded joints whose clamped parts slip relatively and the following were derived: (1) the condition necessary for the bolts to loosen by self rotation, (2) the physical meaning and the theoretical equation of the critical slippage between the clamped parts, (below which the bolts do not rotate), (3) the theoretical equation of the bolt loosening angle under the above-mentioned condition. Simple experiments were carried out to measure the friction coefficient of the bolts under the transverse slip of the clamped parts. Specifically, the critical slippage between the clamped parts, and the bolt loosening angle with the clamped parts making an arc slip were measured. The theoretical and empirical results were then compared.
46 citations
TL;DR: In this article, a turning test on glass-fiber-reinforced-plastics was performed with several tool materials, e.g., sintered carbides, cermets and ceramics, and the wear patterns and wear land growth rate were analyzed to clarify the relationship between physical (mechanical) properties and flank wear of cutting tools.
Abstract: A turning (facing) test on glass-fiber-reinforced-plastics was performed with several tool materials, e.g., sintered carbides, cermets and ceramics, and the wear patterns and wear land growth rate were analyzed to clarify the relationship between physical (mechanical) properties and flank wear of cutting tools. The main results are obtained as follows: (1) When cutting speed is increased, the rate of wear on the nose in every tool material starts to increase remarkably at a certain speed, i.e., a critical speed. (2) Thermal conductivity coefficient versus critical speed curve is approximately linear when plotted on log-log coordinates. The higher the thermal conductivity coefficient of tool material, the higher the critical speed becomes. There also seems to exist an influence of the compressive strength and thermal expansion coefficient of tool materials on its performance in high speed cutting of GFRP.
46 citations
TL;DR: In this article, the general theory of dynamics of four-bar linkage with clearances at all turning pairs, using a continuous contact model, based on the assumptions that the pin is always in contact with the socket in each pair, is described.
Abstract: This report describes the general theory of dynamics of four-bar linkage with clearances at all turning pairs, using a continuous contact model, based on the assumptions that the pin is always in contact with the socket in each pair Dynamic motion of the linkage is analytically treated, and four coupled differential equations for the contact angles and one differential equation for the input torque are presented According to the present theory, the forces acting at the joints are derived
45 citations
TL;DR: In this article, the authors considered a single-stage Stoeckicht planetary gear (Type 2K-H) as a model which took the tooth stiffness and the run-out errors of each gear and so on.
Abstract: The authors considered a single-stage Stoeckicht planetary gear (Type 2K-H) as a model which took the tooth stiffness and the run-out errors of each gear and so on. And the authors statically analyzed the relation between the run-out errors and the motion f the center of the sun gear, and further compared the calculated results with the measured ones. The conclusions are as follows : (i) The motion of the center of sun gear draws a trochoid curve. (ii) In the torque of higher-speed shaft, there is a variation whose frequencies coincide with the number of the relative revolutions of each gear for carrier, and also there may be a variation whose frequencies coincide with the number of the revolutions which can be obtained by adding or subtracting these numbers of the relative revolutions.
40 citations
TL;DR: In this paper, the relationship between the frequency and the damping capacity or the slip ratio and between a damping joint and the mode of vibration was investigated with two kinds of jointed cantilever beams which are connected with a single bolt and several bolts respectively.
Abstract: The heavy machine tools are often made of welded steel and at the same time jointed beam or a damping joint is often used. However the behaviour of the damping capacity of higher mode of vibration of the jointed beam has not been yet fully clarified. In this paper the relationships between the frequency and the damping capacity or the slip ratio and between the damping capacity and the mode of vibration have been experimentally studied by the use of an improved band-width method with two kinds of jointed cantilever beams which are connected with a single bolt and several bolts respectively.
38 citations
TL;DR: In this article, the authors carried out experimental investigations about the dynamic load and the torque variation in two cases, in which the meshing-phases of each planet gear in a single-stage Stoeckicht planetary gear differ.
Abstract: The authors carried out experimental investigations about the dynamic load and the torque variation in two cases, in which the meshing-phases of each planet gear in a single-stage Stoeckicht planetary gear differ. The results are as follows : (i) The variation of dynamic load due to the errors per mesh in the case in which the meshing-phases of each planet gear are equal is smaller than that in the case in which they are different. But the torque variation of a higher-speed shaft in the case of the former is larger than that in the case of the latter, because the phases of the variation of dynamic load at three meshing points are equal. (ii) The modes of free vibration at the resonance frequency of ring gear change according to the meshing-phases of each planet gear.
31 citations
TL;DR: In this paper, the authors adapted the continuous contact model for analysing the dynamics of the crank-lever mechanism with a clearance at the joint of coupler and lever, and the results of numerical calculation of the link motions, input torque and experimental results for the input torque are shown.
Abstract: The method employing the continuous contact model is adapted for analysing the dynamics of the crank-lever mechanism with a clearance at the joint of coupler and lever. Results of numerical calculation of the link motions, the input torque and experimental results for the input torque are shown. They are compaired with the results on the mechanism with a clearance at the joint of crank and coupler in the 2nd report, and the effects of the amount of the variations of clearance, driving speed and mass ratio of coupler and lever on the input torque are discussed for the design of linkage.
28 citations
TL;DR: In this paper, the mechanism of deformation in tube spinning is discussed on the basis of the observation of metal flow experimentally, where the volume of the material built up in front of the roller, the critical reduction of the thickness of the tube and the elongation of tube during the process are estimated quantitatively and then, it is proposed to introduce the parameters of deformations ξ and z0 which are useful to explain the complex flow of the metal under the roller.
Abstract: The mechanism of deformation in tube spinning is discussed on the basis of the observation of metal flow experimentally. The volume of the material built up in front of the roller, the critical reduction of the thickness of the tube and the elongation of the tube during the process are estimated quantitatively and then, it is proposed to introduce the parameters of deformation ξ and z0 which are useful to explain the complex flow of the metal under the roller. From the accuracy of the diameter of the parts and the results of the measured working forces, optimum working conditions are shown which are useful for practical purposes in the industry. Besides, the process of two passes of a staggered roller is recommended from the results of comparison with one pass process of the roller.
TL;DR: In this article, the forces acting at the joints of a crank-lever mechanism with a clearance at turning pairs are found by a straightforward solution of the equations of motion of the moving links.
Abstract: The forces acting at the joints of a crank-lever mechanism with a clearance at turning pairs are found by a straightforward solution of the equations of motion of the moving links. In each case of the mechanism with a clearance at the joint of crank-coupler or coupler-lever, the forces acting at the joints are calculated by the kinematic analysis in 2nd and 3rd reports. The following points are discussed: (1) a shaking force acting on the frame, (2) effects of the amounts of clearance, driving speed and mass of link on the forces acting at the joints, and (3) comparison of the direction of a force acting at the joint with the contact angle and the limits of applicability of the continuous contact model.
TL;DR: In this article, the roughness effects on the three-dimensional boundary layer flow along an enclosed rotating disk have been studied theoretically and experimentally as well as the admissible roughness.
Abstract: Roughness effects on the three-dimensional boundary layer flow along an enclosed rotating disk have been studied theoretically and experimentally as well as the admissible roughness The results show that an increase of roughness of the rotating disk results in an increase of core rotation and then in a considerable increase of pressure drop toward the disk centre, that an increase of roughness of the chamber wall has reverse effects, and that the equal roughness of both walls makes the flow almost same as one along smooth surfaces The theoretical results based on the logarithmic velocity distributions show good agreement with the measurements The well-known formula of admissible roughness in the two-dimensional flow is confirmed to be effective even in the three-dimensional boundary layer flow, because the secondary flow has little effect on the flow in the immediate vicinity of the wall and then the viscous sublayer is not influenced so much
TL;DR: In this article, preliminary studies on the reliability of a transient hot-wire method and measured results of eight liquids are described, including water, methanol, ethanol, benzene, acetone, glycerin, refrigerants R11 and R113 at atmospheric pressure in the temperature range -90 - + 80°C.
Abstract: In this first report in a series of studies to measure the thermal conductivity of fluids at high temperature and high pressure, preliminary studies on the reliability of a transient hot-wire method and measured results of eight liquids are described. Measurements were performed for water, methanol, ethanol, benzene, acetone, glycerin, refrigerants R11 and R113 at atmospheric pressure in the temperature range -90 - +80°C. Empirical correlations were established for each liquid. Comparisons with available data in literatures showed reasonably good agreement for most of liquids.
TL;DR: In this paper, the free vibrations of a string with time-varying length are analyzed and the equations of motion with respect to the new variables are solved by method of separation of the variables.
Abstract: Free vibrations of a string with time-varying length are analyzed. An equation of motion is the well-known wave equation. Since the length of the string varies with time, its free vibration can not be determined by previous methods. Therefore, new variables of position and time are introduced and the equations of motion with respect to the new variables are solved by method of separation of the variables. Though so-called "eigenvalues (or eigenfrequencies)" and "eigenfunctions" are determined, "eigenfunctions" and initial conditions are expanded into Fourier sine series and then algebraic equations of infinite dimensions are introduced. In such a way, the free vibrations are solved.
TL;DR: In this paper, free and forced vibrations of a string with time-variable length are treated theoretically under the assumption that the variation rate of the length of the string is small, and the solutions are obtained n the form of a power series of a small parameter which prescribes the variation rates of length.
Abstract: Free and forced vibrations of a string with time-variable length are treated theoretically under the assumption that the variation rate of the length is small. The solutions are obtained n the form of a power series of a small parameter which prescribes the variation rate of the length. The theoretical analysis shows that the free vibration has a nature of a travelling wave. As to the forced vibration occurring during a transition through the fundamental resonance point, the analysis shows that the amplitude becomes maximum slightly later than the moment when the "natural frequency" of the system coincides with the frequency of the external force. An experimental analysis is performed for the forced vibration. The comparison of the results of the theoretical analysis with those of the experimental analysis shows a fairly good agreement.
TL;DR: In this article, the authors proposed a usefull measuring method based on the theory of propagation of longitudinal elastic stress wave, which can estimate the external force ranging from quasi-static to impact, at the end of a cylindrical bar can be estimated by measuring stresses at two suitable points on it.
Abstract: The impact force is measured usually by the method of Hopkinson Pressure Bar. However, the measurable time range of this method is restricted by the length of the bar. The author suggests a usefull measuring method based on the theory of propagation of longitudinal elastic stress wave. In this method, the external force, ranging from quasi-static to impact, at the end of a cylindrical bar can be estimated by measuring stresses at two suitable points on it. Also the length of the measuring bar can be shorter than in another methods.
TL;DR: In this paper, the shape optimization problem for a structural beam where its allowable displacement is restricted under multiple loads is addressed, and a growing-reforming procedure is employed to evaluate the envelope of the stress induced by the possible loads.
Abstract: This paper deals with the shape optimizing problem for a structural beam where its allowable displacement is restricted under multiple loads. A Growing-Reforming Procedure proposed by the authors is employed. The Procedure is extended to the cases where a beam has to support a number of possible loads ; that is, a method to evaluate the envelope of the stress induced by the possible loads. In order to make allowable displacement within a restricted value, a combined method of sensitivity with the Growing-Reforming Procedure is introduced. A computational algorithm based on this method is established. Some typical applications are shown to demonstrate the effectiveness of these methods.
TL;DR: In this paper, a polygonal plate is formed by setting some rigid line supports on a simply supported rectangular plate, and the reaction force and moment acting on all edges of the polygonian plate as unknown harmonic exciting loads are obtained.
Abstract: This paper presents an analytical method to study free vibration of polygonal plates clamped at the edges A polygonal plate is formed by setting some rigid line supports on a simply supported rectangular plate Regarding the reaction force and moment acting on all edges of the polygonal plate as unknown harmonic exciting loads, the stationary response of the plate to these loads is obtained The force and moment distributed along the edges are expanded into a Fourier sine series with unknown coefficients, and homogeneous linear equations are derived with use of restraint conditions at the edges The natural frequencies and the mode shapes of the polygonal plate are determined by calculating the eigenvalues and eigenvectors of the equations From the numerical calculation carried out on an equilateral triangular through a regular octagonal plate, it was clarified that the mode shapes of clamped polygonal plates can be classified into several groups of various types
TL;DR: In this article, the temperature distribution due to the heat input was analyzed by the Fourier heat conduction equation, and the stationary deflection and stresses of the plate induced by the thermal moment were analyzed theoretically.
Abstract: Recently, thermally induced vibrations have assumed increased practical importance in many industrial fields, and some methods of analysis were developed to study the vibrations of beams and rectangular plates induced by external heating. However, only a limited number of papers are available on circular plates. This paper studies the thermally induced vibration of a circular plate and an annular plate. The plate is subjected to a sinusoidally varying heat flux on one surface, while the other surface is thermally insulated. The temperature distribution due to the heat input was analyzed by the Fourier heat conduction equation. The thermal moment due to the temperature was calculated and the stationary deflection and stresses of the plate induced by the thermal moment were analyzed theoretically. Some interesting phenomena were revealed as the result of the numerical calculation carried out by the application of the theory.
TL;DR: In this paper, the fundamental features of the distortional deformation of an open-cross-section member are studied and the analytical models are restricted to the members of one-degree-of-freedom.
Abstract: The essential features of the distortional deformation of an open-cross-section member are studied. The analytical models are restricted to the members of one-degree-of-freedom. The assumptions used in the semi-membrane theory are employed, and one dimensional analytical method applicable to distortional deformation is introduced. The concept of two shear centers of distortion can be introduced. This is an extended concept of a centroid and a torsional shear center. The distortional bimoment introduced here should be taken into consideration as a generalized force. According to the results of the calculation of a cantilever, the stress value at the fixed end has the possibility of being about twice as high as the value of the conventional beam theory.
TL;DR: In this article, the evaporation process of a single droplet of n-cetane and n-heptane on a hot surface was investigated and the results of the experimental study were clarified.
Abstract: This paper concerns the evaporation process of a single droplet of n-cetane and n-heptane on a hot surface. The initial diameter of the droplet is approximately 2 mm and the hot surface is made of stainless steel and the range of its surface temperatures is between 300°C and 600°C which involves the maximum evaporation rate point and the Leidenfrost point. From results of this experimental study, the effects on the evaporation life time of the gas temperature around the droplet and of the surface roughness are clarified. Furthermore, by the observation of the evaporation process through a high speed camera, the evaporation life time curve is divided into 6 regions according to the mode of evaporation of the droplet. Especially, the evaporation process in the transition region can be interpreted by the successive change of the modes of evaporation, that is from the contact evaporation to the spheroidal evaporation.
TL;DR: In this article, the authors carried out an experimental investigation about the torque variation in a single-stage Stoeckicht planetary gear (Type 2K-H) constructed with spur gears.
Abstract: The authors carried out an experimental investigation about the torque variation in a single-stage Stoeckicht planetary gear (Type 2K-H) constructed with spur gears with the following results : (i) The torque variation in the planetary gear is caused by the errors per mesh and the run-out errors of each gear. (ii) When the number of error cycles per mesh coincides with all kinds of natural frequencies of the planetary gear, the torque variation of higher-speed shaft increases. (iii) A resonance is caused in the gear testing machine with a planetary gear by the run-out error of the sun gear. Consequently, the torque variation of lower-speed shaft increases.
TL;DR: In this paper, the load distribution of a toothed belt whose pitch is different from that of pulley is discussed theoretically and experimentally, and the effectiveness of the theoretical prediction on load distribution is proved by the experimental results.
Abstract: In this paper, the load distribution of toothed belt whose pitch is different from that of pulley is discussed theoretically and experimentally From this study the following conclusions have been obtained : 1) The pitch difference exerts an important influence on the load distribution, so the most suitable pitch difference should be chosen in consideration of the transmissive load, the modulus of elasticity of the belt, the compliance of the bled tooth, the coefficient of friction between belt and pulley 2) The effectiveness of the theoretical prediction on load distribution is proved by the experimental results
TL;DR: In this paper, a method of determination of the oil film thickness from the contact behaviors between the rolls and the strip is proposed, where the surface roughness of roll is measured by means of a similar method to that proposed by Saeki et al. The measured values are in good agreement with the calculated values.
Abstract: Author proposes a method of determination of the oil film thickness from the contact behaviors between the rolls and the strip. The oil film thickness at the contact hcon is written as hcon = (the surface roughness of roll) × 1/2 + (the surface roughness of strip) × 1/2 The oil film thickness in rolling is measured by means of a similar method to that proposed by Saeki et al. The measured values are in good agreement with the calculated values. When the oil film thickness is greater than hcon, the reflection in the rolling direction R agrees with that in the transverse direction R90. When that is smaller than hcon, the reflection in the rolling direction is higher. Consequently, a parameter which can represent the lubrication mechanism in cold rolling is derived as α=R/R When α=1, the lubrication mechanism is hydrodynamic and when α > 1, that is boundary.
TL;DR: In this article, the influence of the transmitted tooth load on the dynamic increment load and others about a sngle-stage Stoeckicht planetary gear (Type 2K-H) constructed with spur gears was investigated.
Abstract: The authors studied experimentally the influence of the transmitted tooth load on the dynamic increment load and others about a sngle-stage Stoeckicht planetary gear (Type 2K-H) constructed with spur gears. The results are as follows : (i) The influence of the eccentricity of lower speed shaft and higher speed shaft can be sufficiently eliminated by using a floated sun gear. (ii) When the natural frequency of a planetary gear coincides with any order of the mesh-frequency, the tooth load varies largely and the momentary load distribution is reduced to inequality. (iii) When the transmitted tooth load becomes small, the dynamic load and the additional torque increase remarkably.