This review describes the recent studies of fluid film lubrication by non-Newtonian lubricants. Present-day lubricating oils contain a large quantity of high-molecular-weight polymers as a viscosity index improver and a viscosity thickener. Greases have been widely used in various types of equipment and machinery to simplify the lubricating system. These lubricants exhibit a non-Newtonian behavior. However, the classical theory of fluid film lubrication deals with the lubricants whose behavior is Newtonian. In recent years, several investigators have studied the fluid film lubrication characteristics of non-Newtonian lubricants in various bearings by considering different rheology models. In this paper, the problems of fluid film lubrication for such lubricants are reviewed by classifying the studies by rheology models.

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A new transfer matrix method is proposed so that it can be used for analyzing st6ady-state responses of nonlinear multi-degree-of-freedom systems. For proposing the method, the quantities describing the dynamic state of the system are expressed in the form of Fourier series, and formuldtion is made with respect to the increments in the Fourier coefficients. As numerical examples, the method is applied to the analysis of harmonic as well as subharmonic oscillations of a three-degree-of-freedom system.By comparing the resu1ts of the method with those of numerical integration of the equations of motion, the validity of the proposed method is confirmed.

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An exact method using power series expansions is presented for solving free vibrations of rotating thin circular cylindrical shells. Equations of motion, which are differential equations with variable coefficients, are solved exactly by power series expansions. Frequencies and mode shapes of rotating circular cylindrical shells with both ends clamped and with both ends simply supported are presented showing their variations with rotating angular velocity.

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Oscillations of a strongly nonlinear system under two-harmonic forcing excitations and joint forced and parametric excitations are investigated. It is obtained that such kinds of excitations tan provide the stabilization of forced and parametric resonant oscillations. Stabilization phenomena include the contraction of an ambiguous zone of oscillations, the increase of stability of resonant oscillations and spontaneous restoration of the resonance regime. These phenomena exist in the case of a nonmultiple ratio between frequencies of excitations, i.e., in the case of asynchronous excitations. It is also shown, that stabilization phenomena are quite similar for nonlinear systems with different types of asynchronous excitation. Therefore, these phenomena can be attributed to the common properties of nonlinear systems.

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This paper describes the general formulation for the in-plane flexural free vibration analysis of a multiple-layered straight-line structure by the transfer influence coefficient method. The structure is modeled as a distributed mass system with lumped masses and lumped inertia moments, and massless linear and rotational springs. The results of the simple numerical computational examples demonstrate the validity of the present method giving the numerical high accuracy and the numerical high speed, compared with the transfer matrix method on a personal computer. The main features of this method are the unification of the frequency equation for all boundary conditions, and the elimination method of the false roots when the bisection method is used for solving the frequency equation. The cancelling attributable to the adding and subtracting of hyperbolic and trigonometric functions is overcome by partitioning the uniformly distributed beams.

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Mechanical snubbers have often been used as supports for the piping in nuclear power plants, but recently, elastoplastic-type piping support devices (called energy absorbers), which are low in cost and maintenance free, have been planned for use instead of snubbers. Under these circumstances, to establish the concept of the piping design using elastoplastic-type piping support devices, a device test and a vibration test of the piping system suppported by elastoplastic devices were performed. Based on the test results, we performed the simulation analysis by various analysis methods. By the results of these investigations, we confirmed the following : ( 1 ) The evaluation formulas for the force-displacement relation and the dissipated energy of devices were established and are considered to be reasonable in comparison with the test results. ( 2 ) By determining that the energy absorber showed plastic behavior at the exciting of S1 level or more, we validated the response spectrum method as a seismic design method.

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This paper deals with an evaluation method for spatial sampling intervals in the measurement or the calculation of sound pressure distribution. In this method, a sampling coefficient is newly defined as the ratio of a sampling interval to the half-wavelength of the sound in question. On the assumption that the sound pressure distribution along an arbitrary straight spatial line in a sound field can be represented by a one-dimensional spatial coordinate in the line direction, it can be theoretically shown that the spatial sampling interval should be set so as to make the sampling coefficient less than 1. In order to examine the influence of the sampling coefticient, three models of sound sources have been used in experimentation. The sound pressure distribution around each model has been measured and calculated for different sampling coefficients. All the results obtained show that the evaluation method using the sampling coefficient is effective and applicable to actual three-dimensional sound fields.

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This paper presents the results of an investigation into the effectiveness of a circular cutting tool with a slit tooth on aerodynamic noise reduction. The aerodynamic noise from a circular cutting tool is caused by vortices generated behind a tooth. It is possible to reduce the aerodynamic noise by controlling the vortices. Using a columnar tooth model with a slit made longitudinally through the tooth, the vortices are controlled by the self-jet from the slit. From the experimental results, the sound pressure level of the aerodynamic noise is reduced and the influence of the slit ratio (slit width/tooth diameter) on the aerodynamic noise is clarified.

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A method is presented for identifying the discrete linear dynamic model expressed by mass, stiffness and damping parameters of a mechanical structure. First, the characteristic matrix of the structure system is determined from the identified modal parameters. Secondary, the mass parameters are identified from the autocorrelation function of the measured responses and the ones calculated from modal parameters in the case of one sine-wave excitation. Consequently the stiffness and damping parameters are obtained from the identified mass parameters and the characteristic matrix. Finally, a numerical simulation example and an experimental example which is a cantilevered pipe structure are demonstrated in detail. It is shown that the present method is applicable for the identification problems of practical structures since the test data can be obtained without additional complications.

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This paper describes an investigation into squealing sounds which occur in a large-sized cylindrical bearing under two testing conditions, a single bearing and a bearing fitted into an annular housing by an interference. Squeal of 4-6 kHz for the single bearing and two kinds of squeals of approximately 5 kHz and 6 kHz for the bearing fitted into the housing occur at the shaft speeds of l000-1600 rpm. These squeal frequencies are not equal to the natural frequencies of the in-plane vibration of the outer race or of the housing including the outer race. The natural frequencies of the in-plane vibration of the outer race coupled with the stationary rollers were calculated, replacing the roller/outer race contact in the loading zone by a spring and considering the friction between the roller and the outer race. As a result, the squeal frequencies approximately agree with the natural frequencies, which indicate an oscillatory instability, and also are close to the natural frequencies of a single roller with a spring.

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This paper presents a new numerical foil-bearing analysis method for two-dimensional foil-bearing problems based on the inverse analysis concept. This method efficiently and reliably provides a convergent solution for a specified bearing surface configuration with a large penetration. Conventional numerical foil-bearing analysis methods are reviewed first, and the problems inherent in the iterative calculation method for nonlinear governing equations are discussed. Then, the substitution iteration algorithm alternating between the time-independent Reynolds equation and the static foil deflection equation is reformulated as the iterative inverse analysis procedure of a set of self-consistent solutlons whose bearlng contour can approach the given value as rapidly as possible. As examples of the numerical calcuIation, a cylindrical foil bearing with a head wrap length of an actual computer tape head is analyzed. Converging characteristics and calculated results are presented.

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A new method for the direct numerical calculation of dynamic characteristics of fluid film lubrication is presented. The present method is derived by applying the boundary-fitted coordinate system to the divergence formulation method. A generalized algebraic equation for perturbed node pressures, derived by the present method, can be widely used to represent the arbitrary film configuration, arbitrary bearing shape and arbitrary vibration mode. As an example of a computer program using the present method, influences on stiffness and damping factors of a spherical spiral-grooved bearing with a radial eccentricity are shown.

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Temperature rises of all parts of gear equipment and oil must be known when the bulk temperature rise of gears is calculated. Though there is a thermal network method which can be used to predict temperature rises in gears, the true state is more complicated and the temperature rise of oil has not been discussed. In the present paper, the heat quantity at no load, the heat release coefficient of the gearbox and the quantity entering the gear axis from the bearing are calculated with experimental data, and the temperature rises of the gear surfaces and oils are measured. A method of calculating temperature rises of all parts of gear equipment and of oil is proposed. The predicted results are compared with the measured values. The contribution of the heat entering the gear equipment and the heat escaping from the gear equipment are calculated based on the predicted results.

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This paper describes the friction loss of internal gear drives. Friction loss of internal gear drives was obtained with various pinion surface finishings by the oil immersion formula which measures the temperature of lubricating oil for test gegrs. The gear friction loss ratios were between 0.28% and 0.84%. Then, statistical analysis of the experimental data was performed. It was found that the friction loss ratio of the internal gear is influenced mostly by gear speed, next by applied torque and slightly by pinion surface finishing. Furthermore, the friction loss of internal gear drives was calculated. The calculated value agreed approximately with the experimental data.

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Recently, plastic gears with lower noise have been demanded for assembly in sound apparatuses. For this purpose, the use of plastics filled with plasticizers for gears has been attempted. when plasticizers are filled into plastics, the deformability increases; on the other hand, the strength and wear resistance decrease. Accordingly, there are some people who doubt their practicality. Therefore, in this study, gears were made of material made by filling more than lO% plasticizers into nylon, and the effect of silencing was confirmed, and the basic characteristics of gears such as the wear of teeth and the change of the tooth profile were experimentally examined.

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In the previous report, the method of calculating the fatigue strength of plastic gears using strain energy was proposed ; however, the conditions only extended to gear life in the ordinary-temperature environment. Recently, the use of plastic gears has expanded, so that they are now used frequently in elevated-temperature environments. For example, the plastic gears used to drive the drying drum in paper-making machines perform at the ambient temperature of about 90°C. Owing to these facts, a method of estimating the operation life of plastic gears is proposed in this report. Here, the change of the properties of teeth due to working temperature was taken into account using the calculation method developed in the previous report in order to be able to cope with the plastic gears operated in the environment of both elevated-temperature and ordinary-temperature.

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This paper presents a study on the residual stresses generated by case-hardening in the splined shaft with straight-sided teeth. A heat conduction analysis and an elastic-plastic stress analysis during the quenching process of the splined shaft were carried out by means of the 2-dimensiona1 finite element method (FEM), with changes of the thermal expansion coefficient and yield stress with the temperature and carbon content being taken into consideration. The effects of the tooth profi1e of the splined shaft and the case depth on the residual stress were examined, and the optimum case depth was clarified.

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The purpose of this paper is the analysis and classification of robot wrist configurations by geometric characteristics of orientation and canceling. The relationships between wrist configurations and these characteristics must be specified for designing the kinematic mechanisms of a robot. The analysis and classification are performed, dealing with a list of useful wrist configurations. The process of establishing the list is as follows : 1) exhaustively enumerating types of wrist combinations, 2) forming rules to exclude duplicate or ineffective combinations among enumerated wrist configurations, 3) listing the useful wrist configurations without duplicate or ineffective configurations. Each wrist combination in the list is analyzed in view of the geometric characteristics consisting of the orientation and canceling characteristics. From the result of the analysis, the respective wrist configurations are classified according to their orientation and canceling characteristics.

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Crawler-type vehicles have a higher mobility on soft ground than wheel-type vehicles because of low-ground pressure and high-driving force. Therefore, it is important to understand the dynamic interaction between the soil and the track shoes durine propelling on soft ground, but there are few studies on such phenomena. Also, the dynamic driving force, the dynamic Rround pressure distribution and the dynamic behavior of the vehicles have not been developed theoretically at all. In this paper, a suitable simulation model, which considers the dynamic effect of the soil, has been proposed, and the equations of motion have been developed by Lagrange's equation.

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The aim of this investigation was to study a manufacturing system by the method of a centrifugal casting technique for a ceramics/metal functionally gradient material (FGM). The centrifugal force enables the ceramics powder in a metal to create a gradient distribution. The mixture consisting of plaster and corundum was chosen as an experimental model. The mixed materials were cast into rings under the combined conditions of four different volume fractions and three different No. times of gravity. The corundum profile was measured and analysed by cubic order polynomial equation. A mathematical model based on the expression was proposed to consider the effects of the volume fraction of the powder and the centrifugal force on the distribution. The model can express the observed distribution fields in a unified manner. A manufacturing system using the model was discussed in terms of whether it satisfies the designed distribution of the powder.

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It is difficult to eliminate recast layers and cracks in laser-machining caramics. These defects significantly detract from the excellent properties of ceramics. This paper describes the feasibility of a crack-free processing method for hot-pressed silicon nitride (Si₃N₄) ceramics using a yttrium aluminum garnet (YAG) laser. The Q-switched YAG laser pulses controlled at below 500 ns in duration and 10 kHz in repetition rate are effective for the purpose of crack-free machining of Si₃N₄ ceramics because the thermal stress is most likely localized only in the laser-heated shallow area. The integrity of the crack-free surface is evaluated by the fracture strength and residual stress. The strength of laser-processed test pieces is reduced by 10 to 20% compared with diamond-ground ones because the high residual compression layer generated during grinding is removed.

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