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稲田, 茂昭 ; 西田, 浩二 ; 鳥羽, 正幸 ; 内田, 憲之
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application/pdf<br />Journal Article<br />The heat transfar of a drop impinging on a heated surface is influenced consid
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erably by liquid-solid contact and the accompanying formation of a vapor film. The aim of this study was to grasp the liquid-solid contact state more quantitatively by informations based on the temperature fluctuation of the heated surface during the impingement and the behavior of the drop on the heated surface. Experiments were conducted using two different drop diameters (2.3 and 4.0 mm), drop subcooling of 88 K, impinging Weber numbers of 12-98, and an initial temperature for the heated surface of 160-420℃. The unique miniaturization behavior of the drop was illustrated schematically by the imageprocessing method. The existence of four drop-boiling heat-transfer modes which clearly could be classified according to the initial temperatureof the heated surface was proved.
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谷藤, 克也 ; 小林, 正樹 ; 永井, 健一 ; 横瀬, 景司
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application/pdf<br />Journal Article<br />The deflation of an airspring deteriorates the riding comfort of railway vehicles due to an increased bending vibration of the car body. This paper describes the results of a calculation
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analysis for the car body-bending vibration with deflated airsprings excited at the car body. The results are summed up as follows. The bending vibration characteristics are affected to a large degree by the damping force acting to the primary suspension (axle spring). In case of the bogie structure in which the frictional force of high damping acts on the axle spring, the natural frequency of car bodybending increases when its airsprings deflate. The natural frequency decreases in the bogie structure which has a low damping force such as the usual oil dampers for the axle spring. Unless the oil damper fails, the acceleration amplitude of the latter structure is less than the former one under the deflation of airsprings.
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小島, 宏行
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application/pdf<br />Journal Article<br />In this paper, the finite element modeling of a flexible rotating plate, in consideration of both the bending vibration and the rotating motion, is presented. The frequency responses of the
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system consisting of the flexible rotating plate and the rotating axis with a torsinal spring and damper are investigated. In the finite element modeling of the rotating flexible plate, the element mass matrix of the rectangular plate element modeling of the rotating flexible plate, the element mass matrix of the rectangular plate element modeling of the rotating flexible plate, the element mass matrix of the rectangular plate element is formulated by use of the shape function derived by Melsoh. This element mass matrix, consists of three parts that correspond to the bending vibration, the interaction between the bending vibration and the rotating motion, and the moment of inertia. By using the element mass matrix, the equation of motion is obtained. Furthermore, the effects of the rigidity of the torsional spring on the frequency responses are demonstrated.
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小島, 宏行 ; 田口, 和哉 ; 辻, 浩明
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application/pdf<br />Journal Article<br />When an industrial robot with a power transmission mechanism such as a harmonic drive gear is operated, vibrations resulting from the torque ripple of the power transmission mechanism are
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frequently generated. However, few studies on robot vibration characteristics owing to torque ripples have been reported. In this paper, the vibrations of a horizontal two-link robot are investigated with consideration given to the torque ripple and the nonlinearity of the power transmission mechanism. In the numerical analysis, the torque characteristics are assumed to be the product of the nonlinear function of the torsional angle of the gear teeth and the torque ripple represented by means of the the Fourier series of the rotating angle of the input axis. Numerical simulation is carried out, and the effects of the torque ripple and the nonlinearity on the vibration characteristics of the robot are demonstrated. The experiment also shows that the torque ripple can cause a good deal of vibration.
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永井, 健一 ; 荒井, 徳幸 ; 長屋, 幸助 ; 武田, 定彦
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application/pdf<br />Journal Article<br />An analytical method is presented for free flexural vibrations of a cantilevered beam with a concentrated mass, introducing the new mode shape function to the Galerkin procedure. The mode
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shape function is expressed with the sum of the product of the trigonometrical function and the finite power series truncated with the fourth order. The trigonometrical function expresses the form of the higher mode of vibration. The coefficients of the power series are determined by solving the homogeneous equations for the boundary conditions of the beam. Applying the Galerkin method, the sets of differential equation in a time function are reduced. It is found that this method gives good accuracy to the natural frequencies and the natural modes of vibration within the limited number of terms for unknown time functions.
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神宮, 利夫 ; 根津, 紀久雄 ; 坂本, 賢治
概要:
application/pdf<br />Journal Article<br />The mechanical components of a ball thrust bearing, constant-velocity universal joint, locker arm of a cam driving a cylinder valve and a ball-type pressure-regulating valve, involve the elements
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of a sphere and an anvil. These are subjected to impact load. In this paper, we suppose a model with the simplest form of only a sphere and an anvil for these complex components. The sphere and anvil are in contact with each other and rest along the straight line joining their centers. When the free-side end of the anvil undergoes the normal collinear impact by travelling around the bar, the impact load transmitted into the sphere adjacent to the anvil is theoretically analyzed by a motion equation and Hertz's contact theory. It is important to find the particle velocity evoked by the arrival of a stress wave at the end of the anvil which is a point contact with the sphere. This particle speed is an initial velocity as the anvil transmits the load into the sphere. The validity of theoretical analysis is confirmed by comparison with an experiment under the same conditions.
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武田, 定彦 ; 長屋, 幸助 ; 永井, 健一 ; 井開, 重男
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application/pdf<br />Journal Article<br />This paper presents theoretical and experimental results for the steady state response of a relaxation-suspension system considering the unsymmetrical damping force under periodic excitation.
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the unsymmetrical damping force has two different values in period of the stroke velocity. In the analysis, exact solutions are obtained by considering the continuity of the response at the boundary in which the damping force varies. Numerical calculations are carried out for various values of the ratio of the damping coefficient. It is found that the reference line of the vibration in the relaxation-suspension system maintains a constant value within the range of the high frequency ratio, while the reference line in the direct-suspension system varies proportionally to the change of frequency ratio. The experimental values agreed fairly well with the theoretical results.
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永井, 健一 ; 長屋, 幸助 ; 武田, 定彦 ; 中村, 欣明
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application/pdf<br />Journal Article<br />Analytical results are presented for nonlinear vibrations of a stretched string connected with a laterally movable end mass at one end. Applying the modified Galerkin method to the basic
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equations, a set of ordinary differential equations with cubic nonlinearity is obtained. The steady-state response is determined by the harmonic balance method. Numerical calculations are carried out for the various values for the end mass to the string and the geometry of the string. It is found that if the mass of the end mass increases to greater than that of the string, the resonant response in the first mode of vibration can be treated as a linear vibration up to a sufficiently large amplitude. However, the resonant curves in the higher mode of vibration show responses with a strong nonlinearity within a small amplitude. The increment of the cross section area of the string also gives a strong nonlinearity to the response in every mode of vibration.
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永井, 健一
概要:
application/pdf<br />Journal Article<br />Parametric vibrations of beams carrying a concentrated mass subjected to both static and periodic axial acceleration are analyzed under four sets of boundary conditions. Introducing
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the mode shape function, which is expressed as the product of the power series truncated to the fourth order, and the trigonometric function, we obtain the boundary conditions at both ends combined with a simply supported end or a clamped end by exchanging the coefficients of the power series. Applying the Galerkin method to basic equations, we reduce the coupled Mathieu's equations. The stability boundaries of the principal, secondary and combination parametric resonances are examined using Hsu's method. Calculations are carried out for various values of the location of the concentrated mass in each boundary condition. It is found that the inertia force caused by the concentrated mass under periodic acceleration expands the instability region extensively. In particular, the boundary is extended when the concentrated mass approaches the end with a movable axial displacement.
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長屋, 幸助 ; 武田, 定彦 ; 井開, 重男 ; 永井, 健一 ; 松本, 康臣 ; 塩野, 二朗
概要:
application/pdf<br />Journal Article<br />This paper proposes an active control damper using an electromagnetic fluid, and presents an expression for obtaining the damping coefficient of the damper. The damping coefficient has been obtained
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by using the solution of the equation for the electromagnetic fluid which includes both Navier-Stokes' equation and Maxwell's equation. Numerical calculations have been carried out for some sample problems, and the effects of sizes of the damper and the magnetic flux density on the damping coefficients have been clarified.
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