[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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In order to suppress the vibrations of a cantilever beam, a new type of dynamic vibration absorber which consists of a double cantilever viscoelastic beam and a spring-viscous damper is proposed in this paper. The cantilever beam is excited sinusoidally at its base. The displacement transmissibility, i. e., the ratio of the displacement at the free end to that of the base, is obtained theoretically by using the transfer matrix method. In the numerical example, the variations of the resonant peaks are investigated when the absorber parameters are changed. Values of the tuning absorber parameters, which suppress the resonances of the cantilever beam, are shown.

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This report presents a load combination methodology for dynamic response analysis problems, based on a stochastic approach which has been practically introduced in the field of random vibration theory. The methodology proposed in this report has the advantageous point that the appropriate correlation effect among combined load component is taken into consideration and is evaluated in terms of the dynamic correlation factor ρ. The specific combination problem discussed here is the calculation of the maximum base shear coefficient of a large-scaled cylindrical liquid storage tank which can be simulated by a simplified lumped mass model, whereby the sloshing effect of the liquid is neglected. It is concluded that the equations of combination constructed here could be applicable for the case where the fundamental natural frequency of a tank is higher than half of the dominant frequency of input acceleration such as seismic ground excitation ; while an equation proposed in a previous report is effective for other case. The accuracy of this method is statistically examined by use of the random vibration technique ; and its advantage over SRSS (square root of sum of squares) law and ABS (absolute value summation) law is examined with the aid of the numerical computation of the practical examples.

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The forced nonlinear vibrations of simple beams supported with two kinds of ball screw type dampers are discussed both numerically and experimentally. The dampers are composed of a ball screw, a flywheel and a flyball or perpendicular type governor, and possess nonlinear characteristics. The beam is replaced by a lumped mass system and the Continuous System Simulation Language is used to simulate the motion of the masses and the damper on a digital computer. The results may be summarized as follows : (1) Two types of dampers are effective for suppressing the amplitude of the beam at the point of attachment of the damper at the first resonance. (2) The linear solution which is solved by regarding the governor as a flywheel differs from the nonlinear solution in the vicinity of the first resonance frequency of the beam. (3) Each damper approaches the snubber for larger values of moment of inertia J of the flywheel, and acts like the dynamic vibration absorber for smaller values of J.

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This paper presents a method for passing critical speeds of a rotating shaft by use of support springs made of memory metals. In this method the vibrations of the shaft due to whirlings are controlled by use of the on (heating) and off (cooling) heat control of the memory metals which support the bearings. In the analysis, the exact solution is obtained on the problem of a multi-span shaft carrying a disc. Numerical calculations have been carried out for some important problems and experimental tests have also been carried out to verify the present control method and the theoretical results.

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This paper presents optimal design of primary stiffness of conventional truck. The aim of this study is to introduce a function which represents optimal stiffness for hunting stability and curving performance. This has been done by analytical and not by numerical calculation. Using simple 4 degrees of freedom dynamic model of truck, optimal primary yaw and lateral stiffnesses were calculated for critical speed of wheelset and truck hunting as functions of various wheelset parameters and creep coefficient. For curving performance judging method was proposed considering any track conditions described by curve radius, flangeway clearance and cant deficiency. Introducing non dimensional flangeway clearance, formalized unbalanced centrifugal force, bending and shearing stiffnesses four equations were obtained. If these equations are satisfied, good curving performance can be expected. Using these results, optimal design of conventional passenger truck for high speed operation has been discussed.

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One of the most important characteristics of a railway system is that many coupled vehicles run in a long train. It forms mass transportation and extends many other advantages. However, most papers have treated dynamic analysis of railway vehicles as a single vehicle. This paper reports a new method using ""an equivalent one car model"", by which we can analyse the response of an intermediate car in a long train to track irregularities ; and also using this method, show the results of the essential difference in vertical frequency response between articulated vehicles and conventional two-bogie vehicles.

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When the emergency brake is applied on a long freight train, severe impulsive coupler forces can be developed under some conditions. Intending to find measures for the reduction of such forces, the authors have repeated computer simulations. As the force varies according to the time following brake application and also the location in the train, the method is intended to display the force of couplers through the time interval concerned. This paper proposes visual image processing on a personal computer for the purpose. The intensity of the coupler force is classified by seven colorimages on CRT. Observing the image and tracing the point of interest on the CRT by MOUSE, we can obtain the necessary deta : time, coupler number and force, at the same time. As an example, the authors applied this method to two trains of almost similar conditions and found the difference of phenomena by means of simulated images.

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This paper considers the swinging-up motion of a pendulum. When torque is applied to a pendulum staying at a natural position, the pendulum moves upward. If the torque is large enough, the pendulum reaches the upright position. If not, the pendulum goes back after defining the maximum angle of rotation. In this case, it is necessary to change the direction of the torque and to continue a swinging-up motion in order to move the pendulum to the upright position. This paper gives the maximum angles and the necessary number of the switchings of torque for various values of torque, and for damping factors. Experimental studies show good agreement with these numerical results.

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One of the most effective ways to realize a high speed positioning control is to lighten the weight of the mechanical parts of the system. But in such a system, flexibility must be taken into consideration in the control theory, otherwise it results in positioning error and remaining vibration. Positioning control depends on an access mode and a positioning mode ; and to realize a high speed positioning control, fast access is required at first. In the access mode, only the positioning of the load close to the object point is required. So in the access mode, it seems to be possible to control a flexible system with an open loop circuit, so long as there exists little disturbance. From this point of view, the access mode of high speed positioning control of a flexible system with minimum input energy is discussed in this paper.

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From our experimental results previously reported, it was considered that the formation of water film between contact surfaces remarkably influenced on adhesion force or contact mechanism under water lubrication. Here are reported the results of numerical analysis based on the Herrebrugh's integral equation for applying the EHL theory to water lubrication of steel rollers. The formulas of film thickness were obtained with various EHL parameters for lower pressure-viscosity coefficient such as that of water. Furthermore, it was shown that the adhesion coefficients previously obtained were well related to the contact load supported with asperities through water film, which was estimated by assuming asperities with spherical summit on one surface and Gaussian asperity height distribution.

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The floating gap of a floating head slider for large capacity magnetic disk files is becoming smaller and smaller, the present values being from 0.3 to 0.5 μm. To accurately predict the floating gap, numerical analysis by the finite element method has been carried out using the modified Reynolds equation with 2nd order velocity slip boundary conditions. The higher order effects of molecular rarefaction are taken into consideration. The calculated results are in exellent agreement with the experimental ones at low sliding speeds and low ambient pressures.

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The friction between a real engineering surface composed of many micro-asperities and a soft metal film is discussed. The frictional coefficient shows a remarkable load dependency when a hard single protuberance of a small radius of curvature is slid on a soft metal surface. This load dependency originates from the ploughing effect induced by the contact pressure and shearing resistance of the soft metal film deforming on the protuberance surface. Next, based on this result, the effect of real engineering surface topography on frictional properties is discussed.

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To certify the effect of the dynamic load on the oil-film-formation under partial elastohy-drodynamic condition in spur gears, the cross-correlation function R_xy(τ) was measured between the insulating voltage of oil-film and the vibration-acceleration in circumferential direction. The measured cross-correlation functions show clearly that the breakdown of oil-film is apt to occur at the maximum of vibration-acceleration. Under a light tangential load, the coefficients of correlations R (O) were minus and their absolute values were large owing to large fluctuation of dynamic load, compared with the case of a heavy tangential load. In the case of a pair of hobbed gears, R_xy(0) had a higher absolute value in comparison with the case of ground gears. However, after the oil-film was almost completely formed by running-in, or when some pittings occurred at gear teeth, the crosscorrelation functions were distorted and the absolute values of R_xy(0) became small.

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This study reports a method of clarifying the fatigue design of bolted joints. Two types of bolted joints are treated-one is the simplest cylindrical joint, and the other is the more practical T-flange joint. The following conclusions are obtained through stress analysis and fatigue tests of the above-mentioned bolted joints ; (1) A method is proposed for expressing the load applied to the bolt in joints by plotting the dynamic stresses of the bolt on the fatigue-limit (Haigh) diagram, taking the maximum load and the preload as parameters ; (2) The stress analysis of the T-fiange bolts is performed. The analytical results show good agreement with the experimental results using the strain gages ; ( 3 ) It is verified by the fatigue test that fatigue design of the T-flange bolts can be done by comparing the above-mentioned load and the fatigue strength of the bolts.

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Few investigations have been carried out on the characteristics of bolted joints subjected to external bending moments. Furthermore, it seems that the characteristics of bolted joints with gaskets or filler plates subjected to external bending moments have not been studied. In the present paper, the characteristics of T-flanges with gaskets (filler plates) are examined. In this study, replacing T-flanges and a gasket (filler plate) with finite strips, the contact stress distribution, the force ratio for the external bending moment (the relationship between an increment (decrement) of bolt axial force and the external bending moment) and the maximum stress produced in bolts are analyzed by using two-dimensional theory of elasticity. For verification, experiments are performed with respect to the force ratio for the external bending moment and the maximum stress. Analytical results are in a fairly good agreement with experimental ones.

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In order to analyze the vibration of a structure whose elements are connected with bolts, it is necessary to estimate the flexural rigidity of bolted connections : But, although a few papers have reported studies of flexural rigidity, it remains to establish a calculation method for flexural rigidity. This paper deals with a calculation method to estimate the flexural rigidity of bolted annular flanged connections subjected to an external bending moment. In the analysis, models for estimating the flexural rigidity K_b of bolts, and of annular flanges K_f are proposed, taking account of the dispersiveness of bolt disposition. Thus, a calculation method for obtaining whole flexural rigidity of bolted flanged connections is proposed, using the values of K_b and K_f For verification, experiments are performed under several conditions. Calculated results are in a fairly good agreement with experimental ones.

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The present paper deals with an improvement of the stiffness of bolted joints in machine tools. In the design of bolted joints, the stiffness, the bolt axial force and the distribution of the contact stress are important characteristics, and they have been investigated by many researchers. But the effects of the tightening position of the thread in a base, the height of clamped parts and the configuration of contact surfaces are not taken into consideration sufficiently. Thus, in the present paper, the effects of the tightening position of the thread in the base on the stiffness and the distribution of the contact stress are examined experimentally in the case where a beam is fastened partially to the base with tap bolts. As a result, it is shown that these effects contribute to the improvement of the stiffness of bolted joints.

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For the improvement of square shell drawability, the so called ""Strain Relief Effect"" is utilized, that is, the metal flow from the corner to the straight side region in a flange is positively promoted by friction decrease at the corner or/and friction increase at the edge of the straight side. The following points were clarified : (1) Increasing the blank size over the square shell limiting drawing ratio, the fracture punch load P_cr increases approximately linearly. However, it becomes constant when the blank size reaches large enough. (2) In this case, the crack initiates and grows along the periphery of the punch shoulder. The crack initiation and growth are restricted locally within the corner region of the punch shoulder. (3) The strain relief effect makes the distribution of meridian tension along the punch shoulder uniform and prevents the local crack. Thus, it improves markedly the square shell drawability.

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This paper deals with a boring bar used for boring operations in a speed range higher than the critical speed of the bar. One of the merits of this boring operation in a high speed range is that chatter-free machining is to be theoretically obtained. In this study, it is shown that the bar must be designed to have external damping as many times as internal damping. Also, it has been proved experimentally that chatter-free operation can be realized. Another unexpected advantage is that in the experiment of boring aluminium work, chips were all broken in short lengths cotrasting to continuous tangly chips in conventional boring.

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Actual cases for which the output event depends on the sequence of occurrences of repairable input events are shown in the FTA of Human-Robot Systems. The necessity of the quantification of consecutive failure logic is emphasized. The exact and approximate methods of calculating the existence probability, and the expected number of occurrences of the output event are given. Input to the consecutive failure logic is assumed to consist of statistically independent, exponentially distributed and repairable basic events.

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The human hand can perform various types of prehension, that is, grasp, grip, pinch, and nip an object. In order to enable a robot hand to do various types of prehension, it is necessary to make clear the function of the palm of a hand and the contact condition (grasping force, contact area, and its centroid) of each finger. From experimental analysis, the form of a palm of a hand is determined mainly from the shape of the object and the type of prehension, and varies with the thickness or diameter of the object. There is a logarithmic linear relation between the grasping force and the contact area in each finger. The grasping force becomes about 1.7 times as large as the weight of the object. If the thickness of the object is large, the medical and the fifth fingers p]ay an important role in various types of prehension.

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