We experimentally examined the vibration response characteristics of tandem circular cylinders with a pitch-to-diameter ratio of 1.5, at which a strong vibrational coupling appears between each cylinder compared with that of 3.0. Experiments were casrried out changing the void fraction from 0% to about 20% (18%∼35%) for each reduced velocity ranging from 2 to 8. The experiments showed the following major results. (1) In tandem cylinders with a pitch-to-diameter (P/D) of, 1.5 air bubbles caused a large vibration in the cylinder system when flow velocity was smaller than that generating the lock-in state in the two cylinders and reduced the vibration slightly for the lock-in velocity range. (2) The response characteristic maps were made to show the effects of air bubbles on the P/D=1.5 tandem cylinder vibration. and (3) Suppression and excitation of the vibration seemed to be caused by the condition of the air bubble distribution in the region between the two cylinders.

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The excitation mechanism of a self-excited oscillation due to the fluid discharge over a flexible werir was investigated both theoretically and experimentally. A new type of hydroelastic instability was discovered during test operations of the Super-Phenix LMFBR reactor in France. According to a recent report by Aita, this phenomenon includes two types of instability modes: one is the sloshing mode which means the oscillation of a weir associated with coupled sloshing modes of both feeding and restitution fluid collectors; the other is a hydroelastic mode which means the oscillation of a weir associated with fluid-shell modes. In this report, the excitation mechanism of a hydroelastic mode is discussed by calculating the excitation energy brought by discharge to the fluid-structure system. The theoretical results for the range of hydroelastic mode instability virtually agreed with the experimental data.

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The fundamental characteristics of elastic dynamic buckling of thin cylindrical shell containing liquid due to seismic excitation, where shear load was predominant were investigated experimentally. The effects of liquid static pressure, fluid-coupled vibration and coupling with ovaling vibration on the threshold of dynamic buckling and on buckling deformation pattern were discussed.

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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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A finite element program is developed for analyzing vibration of piezoelectric structures. The validity of the program is confirmed by comparing the computed results with those of an experiment conducted on a piezoelectric unimorph cantilever beam. The vibration analysis of the stator of an ultrasonic motor is carried out by employing the program, and the frequency response, the characteristics of the travelling wave, and the trajectory of a particle on the surface of the stator are computed. It is shown that the surface shape of the stator plays an important role in the efficiency of an ultrasonic motor.

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The three dimensional vibration is analyzed for cantilevered elastic bodies of arbitrary shape. The analysis is based on the three dimensional theory of elasticity. Arbitrary shape of the elastic body is accommodated in the Ritz analysis by use of power series displacement functions and by integration over partitioned elements. A computer program code is developed to calculate natural frequencies of elastic solid bodies of complicated shape. Numerical examples are given for elastic bodies, including truncated quadrangular pyramids and cone cylinders for comparison, and for practical application, vibration of the thick turbine blade is analyzed.

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This paper describes methods for measurement of vibration intensity. The object is to make differences clear in effectuality of the methods to the search of exciting and absorbing points on homogeneous beams or flat plates. The intensity measurements studied are the finite difference method, the finite difference method neglecting the cross terms of the two directions in the plane and the cross-spectrum method, in which the second and third methods are compared with the first basic method. The vibration intensity maps evaluated by these methods based on computational frequency response simulations show that (1) the cross-spectrum method which holds on the assumption of complete free field is effectual for the survey of paths of vibration energy flow in the rough, but it is not effectual for the search of the exciting and absorbing points, but (2) the finite difference method neglecting the cross terms is effectual for the survey the of paths and the search of the points.

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The idea of a tendon vibration control system for the flexible space structure has been proposed, and to verify the feasibility of this concept for a cantilever beam-like flexible space structure, a hardware model was constructed in the laboratory. this paper discusses the hardware experiment of the tendon control system for a clamped-free flexible stainless-steel beam hung in the vertical direction. Since the test structure has very low damping, a low-order modal controller becomes unstable due to the truncated modes in the controller design called residual modes. This phenomenon is called spillover. In order to avoid the spillover instability, two different approaches to the control system design are examined both by numerical simulations and by hardware experiments. First, the DVFB(Direct Velocity Feedback Control) which adds damping to all the vibration modes like a passive damper, is applied. Next, a state feedback controller based on a reduced-order model which is called the HAC(High Authority Control), is applied and results in a spillover instability, Finally, a hierarchical controller called LAC/HAC(Low Authority Control/High Authority Control) considering of the DVFB(LAC) for damping augmentation of the truncated modes, and HAC is applied. As the result, the closed-loop system becomes stable and high performance is achieved.

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A digital optimal regulator technique is introduced in the problem of the active vibration control of a cantilever beam. A pair of piezoelectric cells are cemented on upper and lower surfaces of the beam and used as the actuator. Influences of the mass and the rigidity of the actuator are taken into account in the anlysis, and the equations of motion for the beam-control system are derived by applying the transfer matrix method. Simulated transient response of the beam is compared with the experimental result. It is found that the effect of vibration suppression is obtained by means of the present technique which compensaties for the calculation lag.

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Improved solutions are sought as an extension of the previous papers in which an exact solution as well as its precise numeration of the free vibration in a quadratic spring system are considered. A characteristic parameter, which is a function of the given frequency and governs all the Fourier coefficients, must be determined by solving a transcendental equation usually by employing a trial scheme. Two polynomials are proposed here to give explicitly the characteristic parameter; these formulae are asymptotically exact in cases of a quasi-linear small vibration and of a strongly nonlinear slow vibration. They are obtained by applying the reversion of power series and cover the entire frequency range with a relative error of less than 10^-14. Some numerical results are demonstrated and the waveform of the strongly nonlinear slow vibration is composed of a pulse train standing on the unstable equilibrium point. Formulae of reversed power series up to the 15th order are derived and listed.

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In the 3rd report, some characteristics of the exciting force acting on a tube array by air-water two-phase flow were shown. In this report the variance of the exciting force by two-phase flow at high temperature and at high-pressure conditions, which reach to 272°C and to 5.8MPa, respectively, are shown. From the experimental data, it is shown that the increase of the temperature or the increase of the pressure leads to the decrease of the excitement load. It is suggested that the exciting force is caused by the intermittently raising water slug, however, the main component of the load might be changed from the impact of the water slug to the flow of the water slug.

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Experimental results are presented for chaotic vibrations of a compressed buckled beam subjected to periodic lateral excitation. A thin duralumin beam coated with a sheet of thin vinyl was used as a test specimen. The beam was clamped at both ends to the base frame of an electromagnetic shaker. Initial axial displacement of the beam was controlled utilizing thermal elongation both of the beam and frame. Typical responses of time history and the strange attractor of the chaotic vibration were observed near the frequency range of the fundamental resonant vibration. It is found that the correlation dimension of the strange attractor yields a value of d=3.8 under twice the axial displacement corresponding to buckling load.

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In a previous paper, as a basis for developing a new identification technique of nonlinear distributed systems based on their dynamical responses, a technique applicable for identifying a nonlinear uniform beam has been proposed. In this paper some generalization is considered so that the technique can identify a nonlinear non-uniform beam. Numerical simulation is conducted, and the technique proposed is shown to be applicable.

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A new transfer matrix method is proposed which can be used to analyze steady-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 formulation 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 results 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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Transient responses of elastically connected double-beam systems are analytically studied, taking into account the effect of axial forces, by means of the Finite Integral Transform technique. The method is applicable to elastically connected two beams which are different in shape or material, and also applicable to many types of initial or boundary conditions unable to treat by most other analytical method. The analytical solution by the present method results in series expansion form in terms of generalized orthogonal eigen-functions arising from the boundary value problem which is associated with equation of motion of the system. For both (i) simply supported double-beam and (ii) double-cantilever, solutions under some types of loading conditions, (a) impulse loading, (b) step loading and (c) moving load, are proposed with a view to examining the transient response of the system.

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The Steady-state response is presented for a damped cantilever annular sector plate with curved radial edges and varying thickness by the Ritz method. The plate is transformed into a regular sector plate with unit outer radius by a transformation of variables. The transverse displacement of the transformed plate is approximately expressed in series of the power function. Substituting the expression for the kinetic energy and strain energy of the plate into a Lagrange equation, we analytically derive the dynamic response of the plate. The numerical examples are calculated for two types of annular sector plates with symmetrically and unsymmetrically curved radial edges. The effects of the damping factor and varying thickness are clarified quantitatively on the steady-state responses of the plate.

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In the experimental modal analysis, correct expression of the frequency response function (FRF) is indispensable for obtaining precise modal parameters by curve fitting. The FRF of a system of multiple degrees of freedom is explained as a summation of The FRF of systems of a single degree of freedom. In this explanation, only the natural modes within the object limits of frequency are adopted, and all natural modes of lower and higher frequency domain are neglected. The error caused by this neglection is revised with the residual terms. The usual residual terms are formulated of two constants called the inertial restraint and the residual compliance. But the revision of the error is not sufficient with these usual terms. A new formulation of the residual terms is proposed in the present paper by the series expansion of the FRF. Namely, FRFs of the lower and the higher frequency domains are expanded by Laurent and Taylor expansion methods, respectively. It is confirmed using both a model and an actual car body, that the proposed residual terms yield more precise modal parameters than the conventional ones.

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In this study, the mechanical system and the circular path control system of a horizontal two-link robot are constructed by utilizing step motors and harmonic drive gears. The effects of the excitation method of the step motors and the shape of the velocity pattern of the circular path control system on the dynamic characteristics are investigated. In the circular path control system, the control pulse generation algorithm to the step motors is constructed by use of inverse kinematics. From the experimental results, it is seen that the circular path control can be achieved with a comparatively high accuracy. Then, it is advisable for stable and fast circular path control without the failure phenomenon of the step motors, to utilize the two-phase excitation method of the step motors and the trapezoidal velocity pattern of the circular path control.

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The motion involved in the artificial finger-tips that turn a slim stick are analyzed on a basis of the stick motion. In most cases when this action is carried out by a human hand, the size of the stick is considered to be small in comparison with the finger-tip size. The basic motion of finger-tips that turn a slim stick is cleared to be consist a twist motion around the surface normal N and two pure rotations around axes A₁, A₂. These two axes are perpendicular to the normal N and to each other, and are defined by two principal curvatures of the surface. The basic motions of two fingers are combined under the conditions of cooperation of two finger surfaces. A coordinate system attached to the stick and the surfaces has some screw motion corresponding to the finger movements. This analysis also refers to a sliding motion on the rolling contact.

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This paper proposes an actuator in the magnetic levitation system using a permanent magnet and an electromagnet. In this system, the gravity force of the masses is supported by a strong permanent magnet in which two identical poles face each other. The vibration due to external disturbances is controled by use of the electromagnet by changing magnetic fluxes of one of the permanent magnets. The analytical expressions for obtaining the levitation force, spring constant and the control force versus the electric current in the electromagnet were derived using the equation of the electromagnetic theory. Numerical simulations under the control using the optimal regulator for the magnetically levitated boby were carried out. To verify the present theoretical results, experimantal results were also obtained.

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This paper is concerned with a study of a multiobjective optimization problem of a circular hump. The objectives of the design are to minimize the maximum value of the maximum accelerations of the drivers occurring while various vehicles with different wheelbases, including long ones, cross a hump at a design speed for the hump and to minimize the maximum difference between the maximum accelerations of the drivers at a specified speed over the design speed. The set of Pareto optimal solutions is obtained by a method consisting of the ε-constant method and a SUMT optimizing a hump in a lump for the vehicles. In addition, relations between the maximum acceleration of the driver and speed of the vehicle crossing the optimum humps are analyzed by means of simulation calculus for each of the vehicles.

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Large-sized cylindrical roller bearings often emit high level squealing in grease lubrication. There are many studies on the squealing sound of the cylindrical roller bearing, however, comprehension of this sound is far from complete. We have measured sound pressure, acceleration of outer race, the roller/race slip behavior, and sound intensity. A main frequency component of the squealing sound is the frequency range of 4∼6kHz which does not coincide with the natural frequencies of the in-plane vibrations of the outer race. A natural frequency calculated by the coupled vibration between the roller of the loading zone and the outer race agrees with the main frequency of the squealing sound.

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This paper describes an investigation into squealing sounds which occur in the large-sized cylindrical roller bearing fitted into an annular housing by means of an interference fit. Squeals of approximately 5 kHz and 6 kHz occur at shaft speeds of 1000∼16000 rpm. These frequencies are not the natural frequencies of the in-plane vibration of the housing including the outer race regarded as a thick ring. Replacing the roller/outer race contact as a spring in loading zone and considering friction between the roller and the outer race, we calculated the natural frequencies of in-plane vibration of the ring coupled with the stationary roller. As a result, squeal frequencies almost agree with natural frequencies which indicate an oscillatory instability and are close to the natural frequency of a single roller.

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This paper describes the analytical method of EHL problems and influences of bulk viscosity on the oil film profile and pressure distribution. Basic equations in this paper are derived taking the viscoelasticity of the oil film into consideration. Numerical solutions of the oil film profile and pressure distribution are obtained for extreme lubricating conditions. Results show that the compression of lubricating oil is delayed and the film thickness and pressure spikes decrease as the bulk viscosity increases.

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Sliding friction behaviors of Cu-10% Sn alloy sintered materials with mineral oil-dispersing fine MoS₂ powders are studied in combination with flat steels at a speed of 0.16 m/s, in an atmospheric pressure at room temperature. The main results obtained are as follows : (1) For sintered materials attempting to penetrate MoS₂ powders with over 0.7μm grain sizes dispersed in mineral oil, the friction coefficient and specific wear rate are close to those of sintered materials containing only mineral oil. (2) For sintered materials containing mineral oil with the dispersion of ultrafine MoS₂ powders having less than 0.3μm average grain sizes, the friction coefficient is less than 0.1 ; moreover, the specific wear rate is also about two orders of magnitude lower than that of sintered materials containing only mineral oil. WS₂ powders with 0.1μm average grain size also has the same excellent behavior.

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The influence of inlet swirls on dynamic fluid reaction moments and forces of a long annular seal was experimentally studied. The experiment was conducted under the parameters of rotor speeds, cylindrical whirling speeds and seal inlet swirl velocities. The rotor and the outer cylinder were set in a concentric condition. The tangential and restitutional moments were derived from the measured dynamical fluid forces in order to investigate the influence of the inlet swirl. Moments and forces were expressed as stiffness, damping coefficients and added mass. As a result, it was found that the dynamic characteristics of moments and forces are affected by the inlet swirl velocity. The cross-coupling terms of moment coefficients change their sign when the inlet swirl velocity turns to the opposite direction.

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In traction drives, the contact force is one of the most important factors used to obtain traction force. A loading cam and preload springs are used in the Half Toroidal CVT (Continuously Variable Transmission) for automobiles. Their use is very practical and it is considered that enough contact force is obtained on the traction contact point. Actually, on the cam surface, there is a friction loss which makes the contact force lower. In this report, the analysis of the cam force is examined and measured actual cam forces under various conditions are shown. The friction loss on the cam surface causes skew of the cam rollers. The friction coefficient is about 0.016∼0.019. The cam force is decreased by almost 20 %.

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The shrink fit between a ceramic shaft and a metal ring with the use of an shrink fitter of bimetal has been developed in this paper. The fitting strengths of the shrink-fitted assemblies were measured from room temperature to 600°C. The contact pressures between the shafts and the shrink fitters of bimetal were also calculated. The ceramic shaft was Al₂O₃ or Si₃N₄. The shrink fitter was a bimetal of SUS304 and SUS403. The outer ring was SUS403. It has been shown from calculations that the shrink-fitted assembly using the shrink fitter of bimetal is somewhat weaker than that using the shrink fitter of SUS304 when the thickness of the shrink fitter in the radial direction is over 6mm. The bimetal shrink-fitted assembly was approximately 3MPa stronger than that using the shrink fitter of SUS304 at 600°C when the thickness of the shrink fitter in the radial direction was 4mm. The fitting conditions under which the bimetal shrink-fitted assembly was stronger than that using the shrink fitter of SUS304 have been discussed.

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In order to avoid the influence of the displacement of gear axes under load upon tooth contact, the authors propose that a projective group of the surface normals should be concentrated upon the intersection point of the plane perpendicular to the wheel axis and the axis about which the worm axis rotates, displacing its position relative to the wheel. This idea was applied to the gear design using an hourglass-worm gearing with an arcuate tooth profile. A numerical analysis indicated that as much as 70∼80 % of the theoretical area of the utilized gear contributed to meshing at their estimated displacement positions.

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The most conventional hourglass-worm gear has a tooth profile of a straight type. This paper introduces an arcuate profile in the hourglass-worm gearing. The worm gear tooth surface is treated as being generated by a torus-shaped grinding wheel that has a circular axial section, and the effects of the radius of the axial section on the constitution of the surface of contact of the tooth surfaces are investigated. Consequently, the followings were clarified : (1) In the region spreading from the central section to the end section of the tooth meshing, the angle between the contact line and the realative velocity of gears can be designed virtually on a right angle. (2) The limit normal point curve can be set on the end-meshing section of the worm thread.

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Owing to the displacement of the gear axes, the worm and wheel seldom operate in their theoretical relative positions. Hence, on practically used hourglass-worm gearings, tooth contacts shift to the boundaries of the tooth surfaced, resulting in edge contact and extreme conditions of load. Assuming that the tooth contact undergoes virtually no change in its real operating position, we expect it to transmit the power highly and smoothly. In this study, the worm tooth profiles are classified roughly into two types (straight type and arcuate type), and the tooth bearing is numerically analyzed in relation to the estimated displacement of the axes. Consequently, the following results were obtained : (1) Area of contact severely decreases except for the concavely arcuate type. (2) On the concavely arcuate type, the diminution rate of the contact area depends on the radius of the circule; the most suitable value of curvature was found.

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Resin concrete is increasingly used in machine tool structures in order to improve the dynamic properties and to reduce the lead time of production. However, it has been pointed out that the thermal and mechanical characteristics of resin concrete are not clarified as yet. In this paper, the thermal conductivity, the specific heat, the coefficient of linear expansion, the Young's modulus and the Poisson's ratio of epoxy resin concrete have been experimentally investigated, and also some theoretical models have been investigated to calculate the thermal and mechanical characteristics. It is concluded from the result; that the thermal and mechanical characteristics of epoxy resin concrete depend strongly on the constituent materials; the relationships between characteristics and constituents are clarified to some extent. It is confirmed that the proposed models can be used to estimate some of the fundamental thermal and mechanical characteristics from the physical properties and volume fluctuations of the constituent materials, which can be used for designing an appropriate resin concrete.

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To calibrate the three-coordinate measuring machine (3CMM) with several kinds of measuring probes that differ in shape and size, it is necessary to know the attitude of the probe about the coordinate axis as well as the error vector. This paper presents a method of determining the attitude of the probe at several positions in the measuring range. In this method, the three-dimensional standard gages of two types and probes of four types with different offeset are used to observe the attitude, and the discrete distribution of the attitude vector is determined. Based on the proposed method, the experimental measurement to determine the attitude vector was performed. The systematic error at any position in the 3CMM can be calculated from the distribution of the error vector and the attitude vector. To verify the measuring accuracy corrected by the systematic error, distance measurements were performed using the gage blocks, and the measured values were corrected. As a result, it was clarified that the correction improves the accuracy of the 3CMM.

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This paper discusses one of three processes of the conceptual design of mechanical systems consisting of link mechanisms, gear mechanisms, etc. The three processes are (1) the determination of design specifications, (2) the automatic generation of mechanical system models which consist of mechanical models having the proper types of input and output motions and positional relationships between input and output axes, and (3) the selection of mechanisms, that is, the process which transforms mechanical models obtained by the second process into link mechanisms, gear mechanisms, etc. This paper deals with the second of these processes. The database of mechanical models, which are classified according to input and output characteristics is used to automatically generate the mechanical system model with one input and one output. For the case of a mechanical system model with one input and multiple outputs, two automatic generation methods, which determine the relationship between mechanical system models with one input and one output, are discussed, comparing the number of mechanism models generated by two methods.

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According to the conventional theory of mechanism, mechanisms are customarily subdivided into those of plane and space. However, since this classification is not dimple enough to lead to a unified theory, a more detailed classification seems to be necessary. Based on this definition of the mechanism is first clarified in this research by classifying the synthetic systems. Then, the content of mobility is made clear by classifying the mobility of contraposition. Furthermore, by establishing the concepts of space freedom and dimensions, and by introducing the concept of 1.5 or 2.5 dimensional space, space mechanisms are subdivided into the various types. Based on the above-mentioned ideas, many of the mechanisms, which have been treated as special cases because of nonconformity with the theory of number synthesis, can be included in the single unified theory.

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