In a symmetrical four-point bending with friction at the loading supports and the reaction supports, the problem of nonlinear large deflections of a thin elastic simply supported beam is analysed by both the numerical method (R-K-G method) and the analytical method using the Legendre-Jacobi type elliptic integrals of the first and the second kinds. Moreover, the reduction techniques are proposed to estimate a maximum deflection, an end slope, a maximum bending stress in large flexural states with friction at both loading and reaction supports from the conventional linear bending theory in place of the exact large deflection theory. The experiment is performed to confirm the applicability of the large deflection theory. The experimental results agree well with those obtained form the presented large deflection theory.

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Dynamic radial and circumferential stresses are analyzed for hollow rotating discs which rotate at arbitrarily varying speeds, and the inner boundary of which is fixed on a rigid shaft. The problem is solved by using the Laplace transform, the convolution and Cauchy's integral theorems. The numerical computations are carried out for the discs which rotate with a constant angular acceleration up to N=10, 000 rpm during the time T_c s, and keep their rotation thereafter. The dynamic stresses give rise to the cyclic variations with respect to time in a constant rotating process. Their amplitude is proportional to T_c for (1/T_c) < 3.4x 10⁴ s^-1 and it reaches asymptotically twice the quasistatic stress as T_c approaches zero. Finally, the obtained results are compared with the quasi-static stresses.

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This paper deals with the stress concentration problem of a finite solid cylinder having a semicircular notch under torsion. The problems treated here are (i) torsion by a pair of rigid chucks attached to the circular cylindrical surfaces and (ii) torsion by surface forces acting on the end faces. Numerical results are compared with the results for an infinite cylinder, and influences of boundary conditions and the length of a finite cylinder on the stress concentration factors are investigated. The principle in the method of solution developed here is an application of Green's functions for torsional body force problems of an infinite thick plate. That is, the method of solution is to distribute torsional body forces in the interior of an infinite thick plate so as to satisfy boundary conditions of a region which is to become a finite solid cylinder having a notch.

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A new crack model which enables us to evaluate crack parameters such as crack energy density and its distribution, COD and COA under arbitrary load history is proposed and the availability of the proposed model is demonstrated through finite element analyses of elasto-plastic crack. The contents are as follows ; (1) A crack model considering the discontinuity in the cracked plane is introduced and the constitutive equation for a plane with discontinuity is formulated on as elasto-plastic case. (2) The finite element formulation of the model is carried out by introducing a plane element. (3) An elasto-plastic crack expressed by the proposed model under monotonic loading is analyzed by finite element method and the availability of the model is verified through the evaluation of crack energy density.

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A combined method of the usual energy method with the rigid plastic finite element method (FEM) is proposed. In this method a velocity field is expressed by a linear combination of a number of simple velocity fields and the unknown coefficients of that expression are determined by minimizing the total energy dissipation. Improved points are as follows : (i) difficulty in introducing a suitable velocity field in the usual energy method is reduced to a great extent, (ii) computation time is shortened by applying a technique in FEM and limitation of degree of freedom in the velocity field in the energy method is removed, and (iii) main part of program of computation is made common to general plastic workings. This method is applied to the analysis of flat-rolling of a bar, and it is found that rolling properties and deformation agree well with experimental ones.

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In the field of bar rolling, many experimental researches have been performed, and various empirical formulas are proposed. But there are few analytical approaches to this subject, because the flow of material in bar rolling is complicated in comparison with that in sheet rolling and it is not easy to determine the three-dimensional kinematically admissible velocity fields. Recently, we have proposed a new energy method using finite element division. In this paper, this method is descrived in application to bar rolling. First, technique of finite element division is suggested in order that we can apply the method to any type of rolling in which central region of material is reduced earlier than the other part. Second, the influence of degree of freedom of velocity fields on rolling properties is discussed, and an appropriate velocity field is proposed. Finally, this method is applied to the analysis of flow of material in two types of bar rolling, square-diamond pass and round-oval pass, and reasonable results are obtained.

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Stress-strain behaviors and ductile-to-brittle transition temperature were examined with a low carbon steel shocked in water by an explosive. With an increasing shock pressure, the yield stress gradually decreased to the minimum at a pressure of 1400 MPa. This minimum value was 62% of the stress for the specimen annealed prior to shock loading. From ageing characteristics of the specimen shock-loaded at 1400MPa, the above decrease in yield stress was supposed to be attributed to generation of free dislocations. Beyond 1400 MPa, the yield stress began to increase from the minimum with an increasing pressure. This behavior was brought about by occurrence of increased twinned grains. The transition temperature of a specimen shock-loaded at 1400 MPa was lower by 15 K than that of an as-annealed specimen, namely, 0.21 K of the temperature was lowered at every 1 MPa of the decrease in the yield stress.

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The thrust force characteristics of oil hydraulic poppet valves are studied experimentally. The thrust force is measured by using two apparatus ; a half cut model and a full shaped model of a poppet valve, with the valve lift X, the seat chamfer length S and the poppet angle 2φ changed. The influence of the change in these three valve factors on the thrust characteristics is made clear by comparison of the thrust coefficients, and the mechanism of the change in the thrust characteristics is also made clear by studying the pressure distributions and the thrust force components within three different region along the poppet surface; the upstream region, the restricted part and the downstream region.

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The double-vacuum phenomenon of a supersonic air ejector having a mixing tube with throat, which appears as a hysteresis on a performance curve, is experimentally investigated under the condition of a constant primary mass flow with the secondary one increased. It is shown that the phenomenon occurs when the induced secondary mass flow increases and a mixed flow of the primary and secondary flows is choked at the ejector throat. Owing to the choking at the ejector throat, as well as a shock wave which is generated by the choking of the flow at the throat of the primary nozzle, another shock wave appears in the section downstream of the ejector throat. The behaviors of these two shock waves are optically observed by a schlieren method, and numerically calculated under the assumption of a one-dimensional steady flow, and it is shown that the calculated results agree qualitatively with the experimental ones.

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The random choice method (RCM) was used to numerically solve shock propagation in a Laval nozzle and a Ludwieg tube. In quasi-random sampling procedure, van der Corput method was used. According to each specified incident shock Mach number and nozzle area ratio, the RCM analysis predicts five unique possible wave patterns. The starting process of the Ludwieg tube was also numerically analyzed by using the RCM.

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Wake structures behind a circular cylinder at Reynolds number of 3.7 × 10⁴ are investigated using a computer aided flow visualization technique, which includes our newly developed conditional sampling procedure. Phase-averaged velocity distributions in the boundary layer on a cylinder are measured and the process of generation and shedding of vorticity are presented. Total circulation discharged from the cylinder surface in a shedding cycle is directly evaluated. Phase-averaged stream-lines and vorticity fields in the wake are obtained, and using these results the coherent structures of the wake flow, i.e., geometrical arrangement, convection speed, a total circulation of a shedding vortex and inner structures of vortices are described. Less than 40% of the discharged vorticity appears in a shedding vortex, and a vorticity distribution in the vortex in the near wake is quite similar to that in an isolated theoretical viscous vortex. But the spacing ratio, convection speed and the drag coefficient obtained do not agree with those calculated from a classical theory.

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Large-eddy simulation is applied to the numerical investigation of a fully developed wall-bounded turbulent flow at the Reynolds number of 11500 with 32×32×32 grid points. Through the observation of the distribution of vorticities, production of Reynolds stress and turbulent kinetic energy, which are difficult to obtain experimentally, the structure of the turbulence is discussed. High speed flow towards the wall and lift-up of a low speed fluid are shown to have a tendency to develop into so-called sweep and ejection. Where these events happen contiguously, high and low speed streaks of streamwise vorticity are observed, which are regarded as the center of the production of turbulence. Well known counter-rotating streamwise vortices are appropriate as the conditionally averaged statistics, but they are not observed as an instantaneous structure in the flow field.

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The coefficient of pressure and the drag and lift forces as well as the local (stagnation, maximum) and mean Nusselt numbers of a cylinder in a rectangular conduit were determined experimentally and compared with those of a cylinder in a free stream. Moreover, in cases that one or two dummy cylinders were set parallel to the test cylinder, the pressure distribution and the profiles of the local Nusselt number around the test cylinder were examined, and the results were compared with those of a single cylinder. From the results the flow characteristics of a circular cylinder in a conduit were revealed.

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Numerical analysis was made of a fully-developed laminar flow in curved pipes of square cross-section under conditions wherein an oscillatory component of flow was superimposed on a steady mean flow. Velocity profiles, stream lines of secondary flow and distribution of wall shearing stresses were calculated in a wide range of various parameters, i.e. mean Dean number D^^-, Womersley number α and flow rate ratio η. It was found that one to four pairs of vortices were induced in the cross section in a cycle at moderate values of α. The kinetic energy of the secondary flow and the resistance factor were described.

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A two-dimensional jet begins to oscillate in transverse direction when it impinges on a wedge-shaped object. This is well known as the edge-tone phenomenon, and many experimental and theoretical studies have been made for a long time. Nevertheless, the mechanism of determination of the oscillating frequency which is one of the most fundamental properties of the edge-tone phenomenon is not clarified yet. In this investigation, the behavior of the oscillating jet and thee mechanism of determination of the oscillating frequency are studied experimentally and a theoretical model which explains these phenomena is proposed. And the propriety of this model is verified by comparison of experimental and theoretical results about the oscillating frequency and the shapes of the streak lines of the oscillating jet.

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This paper is a report on experimental results concerning the relationship between the fiber concentration of pulp suspension flow and the flow velocity for different shapes of turbulence generating means (orifice plate). The instantaneous concentration variation as spatially averaged in the duct width direction was measured by an optical method. The results show : (1) the upstream condition affects the fiber concentration unevenness cY^^' on the downstream side over a long distance ; and (2) the increment of cY^^' from its limit value cE^^', or " cY^^' - cE^^'', is well-correlated with a simply defined non-Newtonian Reynolds number, which can be easily determined.

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In order to improve the life and reliability of piston pumps and motors, it is essential to from a fluid film between the valve plate and the cylinder block. In this report, therefore, possibility of fluid lubrication is theoretically analyzed for the combination of a valve plate with conventional hydrodynamic pads and a cylinder block supported by both an outside journal bearing and an elastic shaft. The fluid film can be formed even in the case of swash plate type axial piston pumps, but a little change in operating conditions results in a large change in the film shape. Thus, even if a stable film is built up, it is liable to break.

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The effect of deposition on heat and mass transfer was investigated both theoretically and experimentally in a finned tube type heat exchanger under frosting conditions. A method for predicting the efficiency of heat and mass transfer was presented based on a uniform frosting model. The predicted results were in good agreement with the experimental data obtained under the two typical operating conditions of heat exchanger, i.e., the constant air flow rate and the constant revolution number of blower.

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Laminar flame development in a spherical vessel has been simulated accurately and solutions have been compared with the ones by the other investigators. The effects of differences in estimating physical values of gases on the calculated results were examined and the incorrectnesses in the analyses which have been revealed until now are pointed out. Accurate simulations give higher convergence ability in deriving the results compared with those by the concepts of isobaric combustion for which heat exchanges are introduced tacitly. It is proved that the relations between mass burnt ratio and pressure increment ratio can be rearranged into a curve irrespevtive of the differences in fuels and initial pressures.

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Generally speaking, geothermal fluids used for operating a turbine for geothermal power station contain several percent (in mass) non condensable gases. The major component of these noncondensable gases is carbon dioxide. For the purpose of clarifying the thermodynamic performance of a geothermal turbine, a calculation formula for obtaining the properties of wet steam mixed with noncondensable gases is shown. And steam table mixed with gases was prepared by using the calculation formula. In addition, the influence of noncondensable gases on the thermodynamic performance of geothermal turbines was also made clear.

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An understanding of the complex behavior of gas mixed steam in its expansion through a turbine stage is essential to the design of efficient and reliable geothermal turbine units. The 1st Report described thermodynamic characteristics and performance of geothermal turbines and showed state equations of steam with noncondensable gases. This 2nd Report presents some experimental results on the behavior of steam with noncondensable gases, such as the equivalent flow coefficient, fluid dynamic loss characteristics and deviation angle in nozzles or cascades. The tests were carried out in a steam tunnel, and measurements were made using the Schlieren method, a pitot probe, and a wedge probe. Results and conclusions obtained from these tests are reported.

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As to the thermodynamic performance of steam turbine to be operated by geothermal steam mixed with noncondensable gases, the 1st and 2nd Reports were presented to report on a theoretical calculation method. To confirm the accuracy of the calculation method, we have compared calculated values with actually measured values based on the results of performance tests conducted at a geothermal power generating plant. The result of comparison and examination shows that the result of calculation wherein the effect of gaseous components is taken into consideration well coincide with the results of performance tests within the range of measurement tolerance, and proves the reasonability of the calculation method.

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Atmospheric turbulence and inflow distortion produced in static test cause the turbofan engine fan noise level difference between in-flight test and in static test. For the solution of this issue, inflow control devices were studied at NAL, which can simulate an in-flight fan noise in ground static test by means of the elimination of inflow distortion and turbulence drawn in by turbofan engines. Based on a lot of basic experimental data, a geodestic 4 m diameter semi-sphere inflow control device (ICD) for large turbofan engines was developed. From a series of tests on aerodynamic and acoustic characteristics of the ICD, it was made clear that the developed ICD is a device which functions effectively for simulating in-flight fan noise in ground static test.

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This paper deals with the natural frequency of an edge-fixed disc in contact with a liquid, which acts as an added mass to the disc reducing its natural frequency. Calculations and experiments are carried out for the following two cases : Disc-shaped liquid is kept on the disc (1) with its free surface parallel to the disc and (2) surrounded by rigid walls without air content. In Case (1) the natural frequency of the disc decreases with an increase in liquid depth, and in Case (2) vice versa. The experimental results agree well with the calculations by means of finite element method within 4.3% error for the nodeless mode and for the mode with one diametral- and zero circular node. A reduction formula for the reducing ratio of the frequency is derived for arbitrary disc thickness, radius and density and also for arbitrary liquid density.

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For the purpose of suppressing the ground vibration as pollution produced by vibrating machines such as forge hammers, press machines and so on, this paper presents a new active force control method -a hybrid force control method. By using both the characteristic of a low pass filter of an elastic support and that of a high pass filter of an active force control method, the hybrid force control method aims to eliminate the exciting force in all the frequency range. First, this paper proposes a principle of the hybrid force control. Secondly, the fundamental characteristcs of the dynamic compensator are shown. Thirdly, from the viewpoint of phase compensation method, the design procedure of the hybrid force control system is presented, and the effectiveness of this method is clarified. Finally, in order to verify the control effect of the hybrid force control, an experiment is conducted.

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In order to suppress the vibration as pollution generated by machines, a new type of an active force control method -a hybrid force control method- was proposed in the previous paper. This method aims to eliminate the exciting force of machines in all its frequency range. This paper discusses the realization of the hybrid force control method from a practical point of view. First, based upon the experimental data, the design procedure of the system is presented. Second, in the suppression of the exciting force, the control effect in terms of an active damper is considered. Third, from a viewpoint of dynamic compensation, the effectiveness as well as the stabilization of the system is shown. Finally, the hybrid force control method including both the characteristic of a low-pass filter of an elastic support and that of a high-pass filter of an active force control method is realized experimentally.

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We discuss vibration phenomena due to an internal resonance in a symmetrical rotating shaft system with nonlinear spring characteristics. Especially, we treat the case that the critical speeds of a subharmonic oscillation of the order 1/2 and a synchronous backward precession coincide with each other. It is revealed that these two kinds of oscillations are coupled by some kinds of nonlinear components expressed by polar coordinates and that unique shapes of resonance curves appear due to the internal resonance. For example, several resonance curves appear in some rotating speed ranges, the region where the subharmonic oscillation occurs is separated into two parts.

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The frequency analysis is presented for rotating cylindrical shells subjected to the initial stresses which are generated by torque, external pressure of axial compression load. Consequently, it is found that, though the natural frequencies decrease depending upon the state of the initial stresses, even in the case of rotating prestressed cylindrical shells the instability phenomenon can't be observed and that the dependence of the frequencies upon the rotating speeds is approximately represented by the simple relation for a thin rotating ring provided that the frequencies and rotating speeds are normalized by the natural frequencies of a non-rotating cylindrical shell.

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This paper present an elastohydrodynamic lubrication of porous bearings applying a modified Darcy's law for non-Newtonian fluid, discusses the lubrication mechanism of human joints, and analyzed a flow of non-Newtonian fluid in porous bearings. It deals also with the effect of elastic deformation on permeability of porous matrix and the influence of squeeze velocity on pressure distributions, load carrying capacities, elastic deformations and flows theoretically. Furthermore, the theory is confirmed by experiments.

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Forced vibration of a gear system excited by transmission error having a period equal to the meshing period and by a random external force, is analyzed approximately by means of an averaging method. Some numerical examples are given. To facilitate analytical treatment, the time varying parameter system is transformed into a time invariant parameter system.

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A spheroidal graphite cast iron has many advantages in manufacturing and physical properties. The previous report showed that the new spheroidal graphite cast iron, which has high strength in as-cast condition, has a good machinability in hobbing tests and a high surface durability in roller tests. In order to apply this new material to medium-hardness gears, the load-carrying capacities are investigated by using a power circulating-type gear testing machine and a pulsator. the new spheroidal graphite cast iron gear has enough surface durability and tooth bending strength in comparison with alloy steel gears. In particular, the tooth surface of this material is smoother than that of alloy steel under the same hobbing conditions, and the material has a long pitting fatigue life. These facts indicate a typical availability of the new spheroidal graphite cast iron.

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Plastic gears have many excellent characteristics which are locking in metallic gears, such as corrosion resistance, self-lubrication, quiet running, and so forth. The meshing behavior of plastic gears is very different from that of metallic gears. Therefore, the life estimation is very difficult for plastic gears. In this paper, generating and growing mechanisms of abnormal wear which appears fatally near the root of plastic tooth are analyzed, and then it is clarified that tooth fractures which take place frequently near pitch point are caused by abnormal wear. Additionally, some methods for extending the life of plastic gears are proposed.

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An approximate equation has been proposed to clarify the rotational vibration behaviour of power transmission helical gear pairs with comparatively narrow facewidth. It has been based on the theoretical deflection solved by one of the authors using the finite difference method. and the rotational vibration has been treated as a single degree of freedom system and the meshing resonance frequency of it has been obtained. Furthermore, its propriety is verified by measuring the acceleration for each gear pair belonging to the three categories classified by contact ratio. it is found that the meshing resonance frequencies calculated by use of the proposed equation agrees with experimental values.

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To clarify the deformation mechanism of tooth surface in the rolling finish of gears, it is necessary to grasp the plastic deformation produced by the rolling. the deformation of tooth surface is affected by the face width and the hardness of tooth. In the present study the rolling finish of rollers is experimented under three conditions of specific sliding. The profile of rolled surface and sides, the radial and axial deformations and the hardness below the rolled surface are measured. The deformation of roller becomes steady after about three to six passes but it is affected by the width of roller. The relations among parameters of deformation are clarified.

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In order to study about deformation and stress characteristic on thin rim gears which is needed to determine the rim thickness, we calculate the deformation quantity and stress values on a removed gear tooth thin plate shell which is one side free and the other side built-in. In this case we neglect the gear tooth itself and accordingly this model deviates far from actual condition, but we can get basic characteristic to calculate rim thickness when concentrated load acts upon the shell. Assuming the above, we point out that the theoretical equation is an approximate equation so it is limited by dimension of shell.

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This paper describes the application of the boundary element method to the stress analysis of a threaded connection where there is a large flat unstressed surface, by using the Mindlin solution that enables us to solve the problem involving free flat boundaries without having to discretize those boundaries. The advantage of this method is in its simplicity of giving data as input for concrete problem undertaken by fastener designer in practice. This method make it possible to analyze the axi-symmetric and the three-dimensional problems of a bolted fastener with a contact surface and under service loading, by using the unit partitioning technique.

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