Showing papers in "Jsme International Journal Series B-fluids and Thermal Engineering in 1967"
TL;DR: In this paper, the authors have focused their attention on the amplitudes of the relative slips near the end of the press-fit, and investigated them quantitatively, and the effects of various factors, such as size, shape, clamping pressures, magnitude of nominal stresses, number of cycles and frequency of alternating stresses, on the amplitude of relative slips are evaluated extensively.
Abstract: Although the significant reduction in fatigue strength produced by fretting of the press-fitted axle assemblies has been well known, the causes of this phenomenon have not been fully clarified. The purpose of this study is to clarify the influence of fretting on the fatigue strength of press-fitted axle assemblies where the minute relative slips at the end region of the hub on the axle surface occur due to the alternate elongation and contraction of the axle fibers. In the present paper, the authors have focused their attention on the amplitudes of the relative slips near the end of the press-fit, and investigated them quantitatively. The effects of various factors, such as size, shape, clamping pressures, magnitude of nominal stresses, number of cycles and frequency of alternating stresses, on the amplitudes of relative slips are evaluated extensively.
37 citations
TL;DR: In this article, the authors investigated the rotating bending fatigue strength of press-fitted shaft assemblies by varying the geometry of the hub and found that the hub overhanging from the shoulder was more preferable with an increase of fatigue limit about 50%.
Abstract: The purpose of this investigation was to improve the rotating bending fatigue strength of press-fitted shaft assemblies by varying the geometry of press-fitted portion. Four groups of 50mm-diam. press-fitted specimens were used. As the result, comparing with the fatigue limit of press-fitted plain shaft, maximum increase of the fatigue limit was obtained for the filletted shaft, in which the press-fitted hub had a low protrusion on the face. Taking the reduction of fretting corrosion into consideration, however, the press-fitting of hub overhanging from the shoulder was most preferable with an increase of fatigue limit about 50%. The fatigue limit of the press-fitted plain shaft could be increased by 50% due to press-fitting of hub which had the low protrusion.
26 citations
TL;DR: In this paper, the authors have analyzed the gas flow of the bearing with added consideration of the circumferential flow in the bearing clearance and the porous bushing, and the theoretical results are investigated experimentally, yielding a good conformity between them enough to certify the theory.
Abstract: For externally pressurized porous journal gas bearings, an analytical solution has been obtained by introducing the concept of the so-called equivalent clearance, but it is not good enough because of the circumferential flow being neglected. In this paper, the authors have analyzed the gas flow of the bearing with added consideration of the circumferential flow in the bearing clearance and the porous bushing. The theoretical results are investigated experimentally, yielding a good conformity between them enough to certify the theory. Then, the optimum design conditions of the externally pressurized porous journal gas bearing are determined theoretically for the various factors which affect the bearing characteristics. Thus, it is made clear that the bearings with the porous bearing surface can have excellent static characteristics.
20 citations
TL;DR: In this paper, the Bauschinger effect in carbon steels has been studied experimentally and attributed to the unevenness of the microscopic internal stress and strain produced by the prestrain.
Abstract: The Bauschinger effect in carbon steels having various structures is studied experimentally. First, the characteristics of the Bauschinger effect in carbon steel are studied and the quantitative description of the Bauschinger effect is made. And then, using this description, the relations between the Bauschinger effect and the prestrain and the structure, the anisotropy of the Bauschinger effect and the process of the removal of the Bauschinger effect by ageing are investigated. In conclusion, the Bauschinger effect in carbon steels is largely attributed to the unevenness of the microscopic internal stress and strain produced by the prestrain.
19 citations
17 citations
TL;DR: In this article, the authors studied the characteristics of these kinds of oscillations and showed that the magnitude of damping ratio has considerable influences on the properties of unstable oscillations, especially on unstable regions and negative damping coefficients.
Abstract: In vibratory systems having multiple degrees-of-freedom and under parametric excitation of frequency ω, oscillations of "summed and differential types"with frequencies ωi (≒pi), ωj (≒pj) take place when ω becomes nearly equal to sum of and difference between two natural frequencies pi±pj=pij, i.e., ω≒pi±pj, even if there is a damping force in the system. In the present paper, the characteristics of these kinds of oscillations are studied in detail, and it is shown that the magnitude of damping ratio has considerable influences on the characteristics of unstable oscillations, especially on unstable regions and negative damping coefficients, and that unstable oscillations can occur only in summed type and not in differential type.
16 citations
TL;DR: In this article, an experimental study has been made to determine the effect of vibration on the rate of heat transfer in natural convection from a horizontal fine wire to various fluids (air, water and ethylene glycol) Frequencies from 0 to 20 c/sec amplitudes from 05 to 35 mm and diameters of wire from 0031 to 0203 mm were employed.
Abstract: An experimental study has been made to determine the effect of vibration on the rate of heat transfer in natural convection from a horizontal fine wire to various fluids (air, water and ethylene glycol) Frequencies from 0 to 20 c/sec amplitudes from 05 to 35 mm and diameters of wire from 0031 to 0203 mm were employed The effect of vibrating motion may be considered in terms of a vibrating Reynolds number Re, based on the mean velocity of a wire Nusselt number may be predicted by the general experimental formula Nu=057Re1/2 where, Re is an equivalent vibrating Reynolds number defined by Re=320 (GrPr)1/3+RePr2/3 and Pr is Prandtl number and Gr is Grashof number Also, three modes in heat transfer were decided by the criterion that the coefficient of heat transfer deviates 5% from the one in pure natural and forced convection The boundaries of three modes may be controlled on the relative magnitudes of vibrating Reynolds and Grashof number and expressed by a dimensionless parameter X
16 citations
TL;DR: In this article, an analysis of static stiffness of a ball bearing which contains three and/or four balls is made as an extension of the former report, where all the effects due to the irregularity usually arising in the course of manufacturing and assembling are taken up for consideration, while the exciting forms of oscillation are actually represented by this ball bearing.
Abstract: An analysis of static stiffness of a ball bearing which contains three and/or four balls is made as an extension of the former report. Though the bearing is far from being useful, it provides us with one of the most important models in examining the spring property inherent in this mechanism. All the effects due to the irregularity usually arising in the course of manufacturing and assembling are taken up for consideration, while the exciting forms of oscillation, as suggested in the former report, are actually represented by this ball bearing which is the most simple practical one. The excitation in the direction of rotor axis is motivated variously : (a) by simple force due to inner ring rotation, (b) by displacement due to rotation of inner ring and balls, (c) by parametric as a Mathieu system due to ball rotation and (d) by variable clearance due to inner ring rotation. Correspondence of exciting form to its cause was disclosed clearly by means of an approximated analytical expression. For instance, it is possible that a mounting error, e.g. an obliqueness of rings, constitutes an important origin of oscillation, especially in the direction of rotor axis, i.e. the so-called abnormal vibration.
14 citations
TL;DR: In this article, the authors investigated how the wear on cutting edges of a blanking tool increased with the number of parts blanked, and discussed the wear influenced the blanking force, energy, dimensional accuracy, burr height, etc.
Abstract: In blanking, many factors influence tool wear. In this report, the authors investigated how the wear on cutting edges of blanking tool increased with the number of parts blanked, and discussed how the wear influenced the blanking force, energy, dimensional accuracy, burr height, etc. (1) On the face of punch and die, crater wear occurred and changed gradually into crater-slope wear with the increasing number of parts blanked, but punch flank wear and die opening wear were slope wear and increased uniformly. (2) Die face wear was greater than punch face wear, but at the sharp corners punch face wear and punch flank wear were remarkable. (3) The blanking force scarcely increased with the number of parts blanked, but the blanking energy increased considerably. (4) Dimensions, burr height and dishing increased and the sheared surface became worse with the number of parts blanked.
13 citations
12 citations
TL;DR: The theoretical analysis of a model of contact which is idealized in one of our test specimen shows that the convergent and divergent heat flows at the metallic contact spots on account of poor thermal conductivity of medium become strong contributory causes for thermal contact resistance.
Abstract: The theoretical analysis of a model of contact which is idealized in one of our test specimen shows that the convergent and divergent heat flows at the metallic contact spots on account of poor thermal conductivity of medium become strong contributory causes for thermal contact resistance. The experimental data on the contact of same metals agree fairly well with the exact solution obtained on the above-mentioned model of contact, assuming that the metallic contact spots are uniformly distributed and their equivalent radii are all of a size and approximately equal to 30μ.
TL;DR: In this paper, the effect of inertia on the flow between eccentric rotating cylinders was studied numerically covering the wide range of the parameters, such as eccentricity ratio, clearance ratio and so on.
Abstract: In this paper the inertia effect of the flow between eccentric rotating cylinders, when outer cylinder rotates, is studied numerically covering the wide range of the parameters, such as eccentricity ratio, clearance ratio and so on. At the same time the whole pressure and shearing distribution and the force acting on the inner cylinder are calculated. The results obtained are as follows. (1) When Reynolds number is constant, the effect of inertia increases as the eccentricity ratio decreases in the range of 0.1∼0.9 and as the clearance ratio increases. (2) When the inertia effect is neglected, the form of pressure distribution in the region of negative pressure is the same as in the region of positive pressure. When the inertia effect, however, is taken into account, the max. value of negative pressure is larger than the max. value of positive pressure. The greater the effect of inertia, the greater the max. value of negative pressure. (3) Considering the effect of inertia, the inner cylinder is acted upon not only by the force perpendicular to the eccentric direction but also in the eccentric direction. (4) Torque acting on the inner cylinder is not influenced by inertia, although the distribution of shearing stress varies depending on whether the inertia force is taken into account or not.
TL;DR: In this article, the buckling of rectangular plates under uniform compression was investigated, which are simply supported along two loading edges and are partially clamped along the other two sides, and numerical calculations were carried out on ten cases, and the diagrams were obtained which give the bucking loads for the rectangular plates of the aspect ratio 1, 2/3 and 1/2.
Abstract: This paper deals with the problem of buckling of rectangular plates under uniform compression, which are simply supported along two loading edges and are simply supported but partially clamped along the other two sides. The energy method is used in investigating this problem which was proposed in our previous papers for solving the general problems of statical deflection, stationary vibration, buckling, etc. of rectangular plates. Numerical calculations are carried out on ten cases, and the diagrams are obtained which give the buckling loads for the rectangular plates of the aspect ratio 1, 2/3 and 1/2. These results are checked by experiments.
TL;DR: In this article, the authors performed theoretical analyses and experimental investigations to give a solution to the separation of tooth meshing, which is accompanied with alarming noise or occasionally abnormal noise. And they considered that an unusual subharmonic noise would be caused by abnormal meshing of every second tooth or every third tooth.
Abstract: Some theoretical analyses and experimental investigations are performed to give a solution to the separation of tooth meshing, which is accompanied with alarming noise or occasionally abnormal noise. Tooth separation occurs at the specific speed defined by the amount of transmission error and tangential load. The more transmission errors are or the less the supplied load is, the lower the speed, at which separation occurs, may become. The largest dynamic load and the highest sound intensity level are presented immediately after the separation occurs. Noise spectra are elucidated in comparison with tooth behaviours. It is considered that an unusual subharmonic noise would be caused by abnormal meshing of every second tooth or every third tooth.
TL;DR: In this article, the effect of the waviness on thermal contact resistance is examined and it is shown that the thermal contact resistances are roughly the sum of the resistances for roughness and wavness in series.
Abstract: The effect of the waviness on thermal contact resistance is examined The experiments performed on a simplified model of waviness show that the thermal contact resistance is roughly said to be the sum of the resistances for roughness and waviness in series Long before investigating the theoretical analyses shown in the previous reports, we have obtained experimentally a practical method of estimating the thermal contact resistance That is, on the assumption that the thermal contact resistance is the resultant of resistances to metalmetal and metal-medium-metal parallel heat flows and the additional resistance attached in series to the metal-metal heat flow, this additional resistance may be taken to be constant for each metal This fact will be verified theoretically
TL;DR: In this paper, the void fraction and the frictional pressure drop were measured for slug and annular twophase upward flow in vertical tubes and some predictions were presented for the shear stress at the interface of the gas and liquid phases and for the flow state of the liquid film.
Abstract: The void fraction and the frictional pressure drop were measured for slug and annular twophase upward flow in vertical tubes. On the basis of the experimental results and the assumption of an annular flow model, some predictions are presented for the shear stress at the interface of the gas and liquid phases and for the flow state of the liquid film. The shear stress at the interface, which is affected by both flow states of the gas and liquid, may be expressed as follows : τi=(ζ/4) (ρgus2/2) where ρg is the density of the gas and us is the slip velocity. The value of the coefficient ζ, defined as above, is calculated from the experimental results and correlated with non-dimensional variables. For the liquid film an equation relating the liquid flow rate and the film thickness is derived from the shear stress distribution in the film by assuming that the film consists of two layers, a laminar sublayer and a turbulent layer. By applying the experimental results to this equation, the eddy diffusivity in the turbulent layer and the velocity distribution in the liquid film are calculated.
TL;DR: In this paper, the problem of elasto-plastic torsion of circumferentially grooved shafts is solved by the same numerical method as presented in the 1st report.
Abstract: In this report, the problem of elasto-plastic torsion of circumferentially grooved shafts is solved by the same numerical method as presented in the 1st report. The solutions based on both flow and deformation type theories are obtained for the Ramberg-Osgood material. The numerical calculations are carried out for several characteristic parameters of material, then the stress and strain concentration factors, stress distributions, the angle of twist, etc. are presented. The results calculated by the flow theory are experimentally verified, and comparing them with the deformation theory, it is proved that both results coincide fairly well with each other about the angle of twist, but about other quantities, for example, the stress and strain concentration factors, the difference between both results becomes larger as torque increases.
TL;DR: In this paper, the formation of a built-up-edge has been differentiated into two mechanisms, that is, adhesion or nucleation of built up-edge and growth of adhered metal.
Abstract: The formation of a built-up-edge has been differentiated into two mechanisms, that is, adhesion or nucleation of built-up-edge and growth of adhered metal. As to adhesion, the affinity between tool and work material has been investigated experimentally. The findings are that the position of a metal in the periodic table and the solubilities of the mating metals are substantially associated with the strength of adhesion. Although the temperature at the interface is primarily significant to accelerate the adhesion, the effect of relative velocity has been revealed to be negligible.
TL;DR: In this paper, a new type of inducer and the addition of an orifice plate placed ahead of it were investigated with a view to overcoming faults encountered in an ordinary inducer by making full use of characteristics inherent in the axial-flow impeller in low flow range.
Abstract: Suction performance of centrifugal pumps can in general be improved by the introduction of an inducer ahead of the main impeller. An inducer is substantially an axial-flow impeller having very steep head-capacity curve and low head coefficient characteristics near normal flow. An ordinary inducer may exert adverse effects on the pump due to the above characteristics. An inducer of special design was investigated with a view to overcoming faults encountered in an ordinary inducer by making full use of characteristics inherent in the axial-flow impeller in low flow range. With the new type of inducer and the addition of an orifice plate placed ahead of it, the values of NPSH at cavitation breakdown points decreased with decreasing flow rates and suction specific speed values of 7000 to 9000 (m3/min, m, rpm) were obtained at low flow rates.
TL;DR: In this article, the temperature distribution inside the carbide tool of a face-milling fly cutter was calculated from the previously obtained data of the tool chip interface temperature during the cutting period in machining a medium carbon steel.
Abstract: The temperature distribution inside the carbide tool of a face-milling fly cutter was calculated from the previously obtained data of the tool chip interface temperature during the cutting period in machining a medium carbon steel. Effects of the cutting speed, tool material grade, use of water-miscible cutting oil, work width and cutter diameter on the surface and internal tool temperature are discussed in the present study. The ratio of the cutting time to the period of a cycle (referred to as the cutting time ratio) is a decisive factor for the internal temperature pattern, and it also determines the cooling rate of the tool surface during the non-cutting time. A modified non-cutting time is proposed as a unique parameter which determines the tool-chip interface temperature during the non-cutting time when different work widths or cutter diameters are used.
TL;DR: In this paper, it was shown that the axial stiffness of a test bearing varies with twice the angular velocity of a retainer, and if the outer race being slightly inclined toward a shaft is fitted on a pedestal, a magnitude of the variation of the stiffness becomes the same as that of a normally mounted test bearing subject to a small thrust load.
Abstract: In this paper, we deal with the vibrational phenomena of a ball bearing of which the diameters of two adjoining balls are larger than those of the other seven balls. As a result, we make clear that the axial stiffness of test bearing varies chiefly with twice the angular velocity of a retainer. In addition, if the outer race being slightly inclined toward a shaft is fitted on a pedestal, a magnitude of the variation of the stiffness becomes the same as that of a normally mounted test bearing subject to a small thrust load. Furthermore, it is clarified that the resonant phenomena appear at certain rotational speeds at which i times, i=1, 2, 3…, of the angular velocity of retainer is close to a natural angular frequency of the system of a bearing having the diameter differences of balls.
TL;DR: In this paper, the authors obtained the thermal stress distributions in a circular disk due to an instantaneous line heat source in the welding practice and showed that the results for the line heat sources in the previous paper may be obtained by integrating the solution in this paper with respect to γ or θ.
Abstract: In the previous paper, we obtained the thermal stress distributions in a circular disk due to an instantaneous line heat source. The present paper is concerned with corresponding results for the action of a point heat source which appears in the welding practice. Numerical work is carried out for the case of the thermal stresses in a circular disk due to an instantaneous hot spot on the middle point of radius. In the final part, we show that the results for the line heat source in the previous paper may be obtained by integrating the solution in this paper with respect to γ or θ.
TL;DR: In this article, the authors carried out further erosion tests in the lubricating oil on copper-lead bearing alloy as well as tin-base white metal and found that the strength in the thin oil film becomes higher as the lining thickness is smaller, because the surface strains are more restrained by the backing steel.
Abstract: In the plain bearing under fluctuating loads, the shaft repeatedly closes to and separates from the bearing surface intermediated by a thin oil film, and occasionally bearing metals show erosion pits or spalling. In the previous paper, erosion tests were carried out by vibrating the disc at the free end of the magnetostrictive oscillator close to the steel plate or the plane surface of bearing alloy lining on steel plate in water or in various lubricating oils. The damages are due to fatigue by the collapse pressure of cavitation bubbles under a thick oil film and due to fatigue by the surface shearing of squeezed film under a thin oil film. At small film thickness, fatigue cracks are found near the periphery of eroded area and these lead to a catastrophic failure of the bearing by flaking off the lining metal. In the present paper, further erosion tests are carried out in the lubricating oil on copperlead bearing alloy as well as tin-base white metal. Copper-lead alloy is damaged more severely than tin-base white metal, because the failure of the former grows in networks of lead. The strength in the thin oil film becomes higher as the lining thickness is smaller, because the surface strains are more restrained by the backing steel. Meanwhile, the effect of lining thickness is hardly found at the thick oil film. Erosion damages in spindle oil with oleic acid are more intensive under the thin oil film than under the thick oil film, because the failure is due to the surface shearing in the former case and to the subsurface damage in the latter case.
TL;DR: In this article, the effects of temperature and strain rate on the compressive strength were clarified experimentally and the particular behaviour at the temperature near blue brittleness was explained using the Cottrell's theory.
Abstract: This paper deals with the dynamic behaviour of 0.03% C steel at high temperature (up to 700°C) within the range of strain rates of 10∼103/sec. The effects of temperature and strain rate on the compressive strength were clarified experimentally and the particular behaviour at the temperature near blue brittleness was explained using the Cottrell's theory. The dynamic stress to cause a certain amount of strain rises with the increase of strain rate at room temperature, but the stress is scarcely affected by the strain rate at 200∼600°C, and then the stress increases again with the strain rate at 700°C. The blue brittleness occurs at higher temperature with the increase of strain rate. For the static test and the dynamic tests of 102/sec, 3×102/sec and 103/sec of strain rate, the blue brittleness temperature is about 200, 550, 600 and 700°C respectively.
TL;DR: In this paper, the fatigue tests on 0.23%C steel were carried out with two superimposed cyclic Ioadings with different repeating speeds, in the case when the repeating speed of the secondary stress, the fast stress wave σa2, was 2000c/min, and the primary speed, the slow one, was 50 or 420 c/min.
Abstract: The fatigue tests on 0.23%C steel were carried out with two superimposed cyclic Ioadings with different repeating speeds, in the case when the repeating speed of the secondary stress, the fast stress wave σa2, was 2000c/min, and the primary speed, the slow one σa1, was 50 or 420c/min. The ratios of those stress amplitudes σa2/(σa1+σa2) were selected in the range from 0.75 to 0.27. Those complex stress patterns were analyzed by the peak pair count method, and the fatigue lives and endurance limits were calulated with the formula ; the method and the formula were proposed by the authors. The calculated values agreed well with the experimental results, even in the case where the primary stress amplitude was larger than the secondary one. It was also clarified that the peak pair count method is more widely applicable to those stress patterns than other count methods.
TL;DR: In this article, a thin liquid layer and a dry part in a contact area of a boiling bubble on a wetted heating surface was clearly obserbed by experiment using an electro-conductive glass.
Abstract: A thin liquid layer and a dry part in a contact area of a boiling bubble on a wetted heating surface was clearly obserbed by experiment using an electro-conductive glass. The thickness of the liquid layer was calculated by reasonable assumption that the shape of a contact bubble on the heating surface is semi-sphere, etc. It was found to be a very thin layer (roughly 10 μ order). And then heat transfer through the thin liquid layer was calculated, and it was found that its coefficient of heat transfer in the contact area of the bubble was very good (roughly 105kcal/m2hr°C order). Therefore we could understand that in the boiling heat transfer a main part is played by the thin liquid layer in the contact area of the bubble.
TL;DR: In this paper, the effect of the oxidation of surfaces on thermal contact resistance is investigated and it is shown that if the surface of a metal is oxidized, the thermal contact resistances becomes greater and its change with the increase of contact pressure is slower than in pure metal contact.
Abstract: The effect of the oxidation of surfaces on thermal contact resistance is investigated. If the surface of a metal is oxidized, the thermal contact resistance becomes greater and its change with the increase of contact pressure is slower than in pure metal contact. From the theoretical analysis these phenomena are explained only by the fact that the oxide of a metal has poor thermal conductivity compared with the pure metal.
TL;DR: In this paper, the spectral absorption coefficients of the bands are determined on the basis of total emissivities data of Hottel et al. coupled with the spectroscopic discussions about the location, width and contour of each band and the band emissivity are evaluated for both CO2 and H2O gases.
Abstract: This paper describes an analytical procedure for getting the band emissivities of carbon dioxide and water vapour and also shows the results of calculations. The wavelength range is divided into four regions, where a strong band is included in one region respectively. The spectral absorption (or emission) coefficients of the bands are determined on the basis of total emissivities data of Hottel et al. coupled with the spectroscopic discussions about the location, width and contour of each band and the band emissivities are evaluated for both CO2 and H2O gases. The summations of the individual band emissivity correspond with the total emissivities of Hottel et al. throughout the parameters (temperature and optical length) of interest. Consequently these results are applicable to the problems of radiative heat transfer, taking into account the monochromatic distribution of energy, the evaluations of the emissivities of mixture gases, etc.
TL;DR: In this paper, the authors investigated the propagation behavior of initial shock front in a shock tube at moderate shock strength and found that the formation distance is more than 20 times the tube diameter and becomes longer at larger diaphragm pressure ratio and lower driven gas pressure.
Abstract: Propagation behavior of initial shock front in a shock tube is investigated at moderate shock strength. Experimental result on the shock speed suggests the following flow model. At early stage of the diaphragm opening, a compression wave races into the driven gas, and it generates and intensifies a shock front. Once the maximum speed is achieved, the shock front gradually diminishes in intensity, overtaken by a rarefaction wave. A platinum wire heat gage is also used to confirm the validity of this flow model. The formation distance is more than 20 times the tube diameter, and becomes longer at larger diaphragm pressure ratio and lower driven gas pressure. Deviation of the maximum shock speed from the theoretically calculated speed depends mainly on the formation distance. The formation distance and the maximum Mach number are better correlated to diaphragm pressure ratio when parametrized by driven gas pressure. As a general remark the formation distance significantly affects the shock tube experiments as well as the shock Mach number does.