From a viewpoint of multibody dynamics, we propose modeling and formulation for such a motion of the rolling disks, and discuss about the mechanism of corrugation development based on the result of the numerical simulation. The unilateral contact between two rolling disks is expressed as a constraint condition on contact point and its surface profile changes with time due to wear development. In particular, we focus on the self-excited vibration with time lag for two disks with rolling contact. In this system, a phase difference between the corrugation profile and the contact force fluctuation influences corrugation development.

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In this paper, the newly produced rail vehicle that has Hybrid Power System consist of a Flywheel, hydraulic switching transmissions and a thermal engine on board is descrived. The Flywheel wears multi layer of Floating Shrouds which reduce aerodynamic drag force drastically, and the Flywheel is applied to super sonic velocity under the atmospheric environment like as in vacuum container. The Hydraulic Switching Transmission is made of our original technology that is newly developed by us. The vehicle has 3 pair of 2 independent wheels mounted on a load equalizer type of bogie with steering mechanism, and each wheel is driven by a hydraulic motor. The gauge is set as 1,067mm.

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A ladder truck with lift mechanism has played an important role in life-saving and fire-fighting. Although the quicker operation mechanism is requested for these demands, the lift operation generates a lot of vibration. Performing the numerical simulations taking the dimensions of the model and the modification of the input motion as parameters, the physical meaning of the dynamic behavior at the time of the lift operation is discussed. Moreover, the optimal control method for minimizing the vibration of a ladder is discussed.

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This paper describes a development of a magnetic levitation system with spin control mechanism. The feature of this magnetic levitation system is using permanent magnets and liner actuators. The levitated object is an iron ball which is suspended by a magnet in the vertical direction and is spun by four magnets in the horizontal direction. Experimental system is introduced. One degree of freedom levitation is examined and carried out. A spinning control strategy is proposed.

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This paper proposes a new type of Hybrid (HB) magnetic bearings which has permanent magnet (PM) within the stator. It is intended for a magnetic bearing to have high efficiency, good dynamic response and low cost. HB magnetic bearing is recognized as an efficient one. But the bias PMs should be installed between the radial magnetic bearings. It requires thick magnetic circuit and produces flux leakage. Hence a new magnetic bearing is proposed based on the HB type. The bias PMs are installed inside the radial magnetic bearing. Hence all the magnetic circuit is closed inside the radial magnetic bearing and it is relatively free from the flux leakage. This magnetic bearing system is controlled using the hall diode as a position sensor which locates on the top of PMs.

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This study presents experimental results and its analysis results of a magnetic suspension and balance system (MSBS) for a high subsonic wind tunnel of Japan Aerospace Exploration Agency (JAXA). A cone-cylinder model was suspended successfully up to 135 m/s flow speed and 13.4 kPa in dynamic pressure at ambient temperature. In this paper, analysis of the control characteristics employed in the tests and consideration of the aerodynamic influence are reported. From these analyses, next improvements of the control system are planned in order to apply to more high flow speed and dynamic pressure.

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In this paper, the newly designed Active controlled Magnetic Bearing that is improved performance of AMB by means of detecting the swaying velocity of the rotating object is described. This advanced AMB is brought near to Zero-power articles. The excellent design on power switching technology in electronics makes a path to the completion of Zero-power AMB. Two types of velocity detectors are produced for test, one is made of variable capacitance, other is made of variable reluctance. And a 10kJ Flywheel is being produced as a test instrument of the plot type AMB.

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Active Magnetic Bearing (AMB) controller can be designed based on linear or non-linear control theory. An example of the former is the PID control that is the most popular and widely used in industries. Variable Structure Control (VSC) is including in the latter. In this study, we added the VSC to an AMB-equipped flexible rotor under the PID control. The sensitivity function is generally recommended for evaluating the stability margin of the AMB linear system, we apply this function even to the non-linear system including the VSC.

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This paper proposes a new modeling technique and control system design for a flexible rotor using active magnetic bearings to control its elastic modes. The purpose of research is to pass through critical speeds caused by elastic modes of the rotor in order to obtain a high-speed rotation. To achieve this purpose, it is necessary to control not only motion but also vibration, because rotational motion affects on vibration. The new modeling method called as an extended reduced order physical model which simultaneously express motion and vibration of the rotor is used. Furthermore, a new controller combined PID with LQ control to flexible rotor is applied.

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In this research, the magnetic gradient drive system is proposed as a HiTc super conductor levitation motor with a new driving method. This drive system rotates the rotation body of apermanent magnet according to a rotating magnetic gradient. This permanent magnet is used as a levitation body of the high temperature superconducting levitation too. In this research, this motor was developed and the utility was verified by the experiment. Moreover, the movement of the rotation levitation body was simulated, and the utility of the theoretical analysis was verified compared with the experiment result.

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The standard PM type self-bearing motor uses surface permanent magnet across which the control fltix should pass. Hence it has trade-off between the strong bias flux and the control flux. This paper proposes a consequent type axial self-bearing motor. Thick permanent magnets are buried in the part of rotor surface. The control flux passes through the rest surface which has low reluctance. Hence it generates rotating torque and axial levitation force effectively. First, the fundamental principle is introduced how the motor produces the rotating torque and the levitation force. Then the motor is designed using FEM. The motor is levitated successfully. But the stable levitation control is not realized when it generates motoring flux. This is due to the magnetic saturation of the stator. To solve this problem, the motor was redesigned. The redesigned motor and magnetic bearing characteristics confirmed high possibility of the proposed self-bearing motor.

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In this paper, a new type of bearingless motor is introduced and some basic experiments on the motor is examined. The feature of this motor is that the rotor has coils with rectified circuit. The rectifier circuit magnetize the rotor in a fixed direction by applying AC power of stator coils. The activated rotor will be rotated as a PM motor. First, the principle of the proposed motor is explained. Next, basic experiments of activation, such as the induced voltage of the rotor coil, the intensity of magnetization of the rotor, and the generating force of suspension and rotation is examined. From these results of experiments, the feasibility of the proposed bearing less motor is discussed.

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The eddy current testing cable is used for inspection of thickness of evaporator tube in Monjyu (fast breeder reactor). This paper deal with the vibration noise of ECT cable generating when this cable is inserted or pulled back in the evaporator tube. We experimented with mock-up and examined characteristic of vibration noise of ECT cable. This experiment showed the vibration noise in inserting ECT cable was bigger than that in pulling back it and the frequencies of vibration were converged on one. We confirmed the countermeasure for ECT cable could control the vibration noise in radial direction of evaporator tube.

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There is a problem of vibration in a diagnosis system of helical evaporator tubes installed in a nuclear power station. Numerical simulations are implemented on the assumption that the vibration is caused by the Coulomb's friction. An analytical model is derived as a large scale nonlinear vibration system and a lot of computational cost would be required to carry out the simulations. The Transfer Influence Coefficient Method, which has high accuracy and efficiency in numerical computations, is applied and efficiently implements the simulations. The vibrations are qualitatively reproduced by the simulations. It enables us to make a pre-evaluation of several means to suppress the vibration and the most effective devise is expected through the simulation.

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The outbreak mechanism of self-excited oscillation of the wire electrode due to corona discharge has not been necessarily given yet. In this paper, the string oscillation placed in the corona discharge field and the ionic flow were measured simultaneously to examine the relationship of the outbreak mechanism of wire oscillation and the fluid force due to the ionic flow. As the result, the characteristic of the ionic flow has four time zone in the formation process and the string oscillation starts to grow after the ionic flow reached the fourth zone of the four time zone.

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In recent years, importance of analyzing complex systems has been increasing from the viewpoint of nonlinear dynamics. Nonlinear dynamical systems can have bifurcation in which a solution changes qualitatively with change of a parameter. If the number of coupling oscillators is large, then : behaviors are usually quite complicated and analysis of them is difficult. To investigate characteristics of such nonlinear coupling, numerical analyses and experiments of forced vibration were conducted by using a dynamical model of a coupled high-T_c superconducting levitation system. Motion pattern of each magnet in time and spatial correlation of all magnets' motion were analyzed by applying FFT, Poincare mapping and POD (Proper Orthogonal Decomposition) to time series data obtained by experiments and numerical analyses. It was found that change in pattern of vibration of each magnet can be accompanied by change in spatial correlation of all magnets' vibration. We also investigated complicated transient behaviors of many coupling oscillators.

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Electromechanical systems can show nonlinear dynamics which is often accompanied by bifurcation. This research investigates bifurcation of equilibrium points and structural stability in a fundamental electromechanical system by doing analysis and experiment. The system has three patterns which differ in arrangement of permanent magnets and an electromagnet. Experiment and analysis of free vibration show us pitchfork, transcritical and saddle-node bifurcation caused by changing current of the electromagnet. We also confirmed structural stability of the saddle-node bifurcation by considering effects of perturbations.

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This paper deals with impact vibration in continuous system excited by periodic displacement with arbitrary functions. The analytical model is steady impact vibration with an attached mass in simply-supported-beam at both ends. The attached mass collides elastically with clamped spring of asymmetrical faces. In order to clarify the main resonance of the system subjected to excitation by displacement, the resulting vibrations are analyzed using the Fourier series method and an exact solution is proposed for this system. Following the theoretical analyses, numerical calculations are performed, and the resonance curves are made using the resulting vibrations. Effects of the stiffness of clamped spring, the ratio of attached mass and the amplitude of excitation on the resonance curves are shown by numerical results. For verification of the analytical method, experiments are performed. The numerical results are in a fairly good agreement with the experimental ones.

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The various motions of hula-hoop were analyzed using the shooting method and ordinary numerical integration. The obtained solutions were verified by the experiment. The results are summarized as follows : There exist many types of motion depending on the ratio of vibration amplitude of supporting point and the length between the center of gravity and supporting point of hula-hoop, namely, synchronized rotation, synchronized subharmonic rotation, harmonic vibration, subharmonic vibration, chaos and so on. It is made clear that the velocity of rotation of the synchronized rotation is not constant, but fluctuates, the solution of synchronized rotation bifurcate to chaos after period doubling bifurcations. The experimental and the analytical results were qualitatively in good agreement with each other.

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In order to obtain a highly accurate periodic solution for systems based on Duffing equation with single-degree-of-freedom, an averaging method, which has been improved through the use of the Jacobian elliptic function, is proposed. Solution by combined Jacobian elliptic cosine and sine function are used as the generating solution of this averaging method. Numerical results of 3rd order subharmonic vibration and 3rd order higher harmonic vibration of forced Duffing oscillator are shown. By comparing with the very accurate numerical solution obtained by shooting method, it is confirmed that the present method is very effective in analyzing periodic solution of subharmonic and higher harmonic vibration.

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In tins study, a simulation method of seismic wave propagation was constructed using the Cellular Automaton method Aground, which is an analytical domain, was divided into cells and the local rules to update state parameters between cells were constructed as well as the local rules about the reflection and transmission between grounds. The intermittent update method was also proposed to adjust the difference of propagation speed of wave. The validity of the method was checked by the comparison of the simulation result with the theoretical one and the measured one and the results agreed well. It was considered that the method constracted in this study was efficient for actual applications.

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Friction characteristic is observed at joints of the structures. A practical estimation method of the first excursion probability of such structures subjected to random excitations such as seismic motions is proposed. First, the first excursion probability of structures with friction is obtained from theoretical method and simulation method. Next, when the tolerance level is normalized by the expected value of the maximum response of the structure with friction, the first excursion probability can be estimated independent of natural period and friction force.

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The transfer stiffness coefficient method applying the graph theory is developed in order to improve the applicability of the previous algorithm. In the new method, the analytical model is expressed by the signal-flow graph, and the optimal computation root in which the computational complexity and the memory requirement are both minimized is obtained by the contraction of the graph. An algorithm based on the present method is formulated for forced vibration of two-dimensional frame structure. The validity of the present algorithm is confirmed by the numerical computational results.

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This report shows a digested summary about the studies on applications of analytic solutions to simulation of vibration problems. Analytic solutions of various theories of continuous bodies can be used to vibration problems of arbitrarily shaped domain. The methods are classified into two typical types. One of them is converting analytic solutions to FEM'like relations. The resulted relations can be connected directly to usual finite elements. The other is the collocation method.

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This papre studies the analytical models for damping evaluation of composite laminates. For this purpose, the frequency equations for cantilevered laminated beams are derived analytically using the Ritz method, based on Classical Lamination Theory (CLT), First-order Shear Deformation Theory (FSDT), and Higher-order Shear Deformation Theory (HSDT), and then fundamental frequencies and specific damping capacities of the beams with different stacking sequences are calculated numerically. The applicability of each model for damping analysis is discussed from the comparisons of the numerical results and experimental results.

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This paper studies the topology optimization of cantilevered beam-type, extruded aluminum structures subjected to multiple combination loadings by genetic algorithm. In optimization, total strain energy of the structure is minimized under a constraint condition, where total number of inner ribs within the structure is kept to be constant, by selecting the locations of the ribs. The deformation of the structure is evaluated by using the finite element analysis developed for two-dimensional elasticity in this study. In numerical calculations optimal design solutions are obtained for the structures subjected to multiple combinations of bending, shearing and stretching loadings.

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This paper presents a procedure to derive reduced-order nonlinear modal equations of circular cylindrical shells. Modal analysis is applied to the nonlinear finite element equation by using base vectors, obtained by the finite element analysis. Base vectors for the transformation consist of dominant linear vibration modes and nonlinear displacement vectors derived approximately from the nonlinear finite element equation. Asymmetry of the deformation of the circular cylindrical shell with respect to its neutral surface is taken into consideration to determine the base vectors. Numerical results show good agreement with those presented in other papers.

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The lateral vibration of pedestrian bridge was induced by human walking in London. It was caused by the synchronization of human walking rhythm with lateral vibration of the bridge, but the mechanism of that synchronization has not been cleared yet. In this paper, the lateral vibration of pendulum with human walking was investigated by using neural oscillators model. Firstly, the neural oscillators themselves were testified numerically whether it could be applied to human walking. Then, human walking model on the pendulum was formulated, combining neural oscillators and the pendulum vibration. Experiments were carried out to investigate the synchronization phenomenon in various conditions and they were compared with the calculated results. The presented neural oscillators might simulate the synchronization of human walking on the vibrating bridge.

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This paper describes an optimal trajectory planning of biped walking. Humanoid robots cost much energy with normal walking. It is important to develop energy-efficient walking and a control method of natural walking. We are interested in natural, high-speed and energy-efficient motion of organisms from a perspective of rehabilitation, medical treatment and engineering application. We obtained the optimal trajectory solution with a minimal square integral of input torque under the full-actuated condition with optimum trajectory planning method developed in our laboratory. Then, I developed a experimental robot and verified this method.

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Players often say that some strings provide a better grip and more spin than others, but ball spin did not depend on string type, gauge or tension in the past laboratory experiment. There was no research work on the spin to uncover what is really happening during actual tennis impact owing to difficult experiment. This study made clear the mechanism of top spin and its improvement by lubrication of strings with high speed video analysis. As the main strings stretch and slide side ways more, the ball is given more spin when the main strings spring back and the ball is released from the strings. More spin produce longer contact time between ball and strings, resulting in the reduction of shock vibrations of the wrist joint during impact

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In this paper, we developed training machine with mechanical impedance display for strength training. This machine using impedance control can impose various loads on trainee in the second half of motion and at a certain moment under movement, such as spring (stiffness), spring and viscosity. By using this equipment, overload principle and specificity principle are considered that compatible training is attained.

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The technique for quantifying stretch reflex allowing multi degree of freedom movement was developed. Measurements are made from a triaxial accelerometer and an instrumented hammer with force sensor system. Stretch reflex dynamics were estimated using the recorded tapping force and the lower leg velocity. The input-output properties of system relating the reflex velocity were characterized using several measures : time delay (Td), reflex acceleration time (Ta), peak leg velocity (Vp), peak tapping force (Fp), peak reflex velocity-peak tapping force ratio (Vp/Fp). These parameters showed repeatability and to help characterize neuromuscular dynamics of stretch reflex. This technique may be also utilized as an educational tool in the medical field.

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Experiments were conducted on pulling head of human volunteers quasi-statically and influence which neck muscle activity responses have on neck bending characteristics was investigated. Experiments were conducted on impacting head of human volunteers and the human neck bending characteristics under different muscle conditions were quantified and analyzed. In this experiments especially, the head was modeled with a rigid body and the neck was modeled with beam, and the neck muscles were modeled with the springs, and the relation of the rotation angle and the moment of the Occipital Condyle joint were quantified as the neck bending characteristics.

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In the present paper the attention is focused on the effects of cavity in in-line tube banks on acoustic resonance which occurred in the two-dimensional model of boiler. As a result, we found many peak frequencies of sound pressure level with different Strouhal numbers, mainly about S_t=0.15, 0.26 and 0.52. The existence of cavities in in-line tube banks caused the resonance of S_t=0.15. The vortex shedding of S_t=0.l5 were generated inside of cavity and the tube banks without acoustic resonance. It was easy to generate acoustic resonance when there were cavities of tube pitch ratio of 2.5〜3.5 in in-line tube banks.

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The purpose of this paper is to clarify the effects of helical strakes around a serrated-fin tube on the vortex shedding. It was made clear that Karman vortex was clearly formed even in the case of a fin tube with helical strakes. The existence of helical strakes around a fin tube caused the decrease of the vortex shedding frequency and the increase of the periodicity of vortex shedding from a fin tube. The coherent scale of vortex in the spanwise direction is larger in the case with helical strakes compared with that of a serrated fin tube.

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In-line oscillation of circular cylinders in a turbulent flow was studied by carrying out the water tunnel experiments with circular cylinders that have finite span lengths, which were supported elastically in two degrees of freedom (in-line and transverse direction). Also, Screens set in the water tunnel generate turbulent flow. As a result, in the case of aspect ratio 15 cylinder, it shows the large response amplitude both in the 1st and in the 2nd excitation region. And the amplitude in the 2nd excitation region is dampened, as the turbulence intensity is larger. Furthermore, the Lissajous figure at 2nd peak changes from a figure of 8 in a smooth flow into a complex elliptical orbit in the high turbulent flow.

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This paper deals with an experimental study of vortex-induced vibrations of bellows structure subjected to fluid flow. The characteristics of the vortex-induced vibrations are examined experimentally with changing the gap length, the pitch length, the arrangement of bellows structure and number of flexible convolutions. The fluid flow around the vibrating convolutions is visualized and the structure of the vortex street is clarified. As a result it is found that the reduced flow critical velocity is about 5, without being dependent on a number and a p/D.

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In this paper, the fluid elastic vibration of circular cylinder-arrays is investigated using the computational fluid dynamics (CFD). The hybrid analytical method which consists of the analytical solution and the simulation solution by using CFD is propsed. Using this analytical method, we estimate the critical velocity and try to make clear about the vibration mechanism of cylinder arrays in unstable condition. Comparing with the reported experimental data, it can be said that the present results show considerably good agreements. Moreover, this present hybrid method is shown to have a good advantage in computation time and man-power.

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This paper deals with the static shape and dynamics of a curved fluid-conveying pipe, which is hanging horizontally and is supported at both ends. First, the effects of the gravity force acting on the pipe, the tension at the supported ends and the fluid force of an internal flow on the static equilibrium state of the flexible curved pipe are clarified theoretically. Second, the forced in-plane vibration of the curved pipe due to the pulsating component of an internal flow is examined theoretically. Finally, the experiments were conducted with a silicon rubber tube conveying water.

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When thin cylindrical shells having freely supported end as labyrinth air seals are subjected to axial leakage flows, an unstable vibration is apt to be occurred. The unstable vibration of thin cylindrical shells is analytically investigated considering the fluid structure interaction between shells and flowing fluids. The coupled equation between shells and fluids is derived using the Fliigge's shell theory and the Navier-Stokes equation. The unstable phenomenon is clarified by root locus based on the complex eigenvalue analysis. The influence of shell-dimensions on the threshold of the instability of the coupled vibration shells and flowing fluids is investigated.

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This paper describes the experimental and analytical study on the instability of falling water sheets. Falling water sheets composing enclosed room with behind wall incite their vibration. This phenomenon leads to low frequency pressure's vibration, and it makes trouble that resonates other structures on such as a dam's gate. On this study, we performed laboratory experiments, and confirmed that S products of its frequency and falling time are uniform to figure a little larger than integer. We consider the vibration is caused by feedback of water sheets kinetic energy through air pressure in enclosed room. The result of this analysis shows the figure S must be about integral value + 1/4. The vibration can be suppressed by cutting off the feedback with a baffle.

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The maenetic damper based on Lorentz Force is suitable for suppressing vibrations of rotating machines or moving machines in a clean room because of non-contact usage. ln this report, we suggest that a conductor of a circular-cylinder-type is added to a magnetic damper for a rotating machine composed of two conductor disks and a round shape magnet. Also we model not only the magnetic damper with the two conductor disks but also with the conductor of the circular-cylinder-type separately. As the result. both the analytical damping ratios agree well with the experimental ones.

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By special designing of two magnetic gaps, made by two pole pieces attached to a ring-shaped magnet and an axi-symmetric inner magnetic yoke, the authors could make a very simple and cheap magnetic damper effective for five axes. The two magnetic gaps have conical shapes which are effective not only for radial two axes vibration but also for axial one. The magnetic attractive forces in the gaps are counteracted by sandwiched gum sheets which also have damping effects. The effectiveness of the damper excluded the gam sheets part is shown by several experiments in which the magnet is included or excluded. A very simple graphical model for each axis which explains damping force due to a.c. magnetic flux generated by vibration was shown.

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Magnetic combined damper is a new damper composed by a set of coil spring, magnetic spring utilizing magnetic attracting force together with damping contributed by eddy current loss. Not like friction dampers, this new damper is basically non-contacting damper with many advantages such as robustness against aged deterioration and temperature fluctuations. Also it is anticipated to be an essential part in order to realize maintenance free machines under a wide variety of environment. However, in spite of the high demand, neither design methodology nor the method of analyzing static and dynamic characteristics is yet established. In this paper, firstly, we developed the model experimental apparatus and examined dynamic characteristics of magnetic combined damper. Secondly, we succeeded in deriving the method of calculating characteristics of the restoring force based on dimensions and material properties. Thirdly, we found a design method of dead band with interesting and useful characteristics.

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Regererative damper has been proposed and successfully reported. A question arrises how we can utilize the harvested energy. This paper introduces a new technology which uses a moving coil type actuator. A PWM step-up chopper is used to regenerate the vibration energy and control the damping force for the regenerative mode. Another PWM chopper is used to control the damping force for the active mode. A simulation is carried out to confirm the proposed control strategy.

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One degree of freedom model has been used in many researches of a overhead traveling crane. We propose two degrees of freedom model considering motion of a hook, and solve the basic behavior making mass ratio between a hook and a crane load mass, length ratio between a lope and a sling lope into a parameter. As a result, When mass and length ratio become large, system can be analyzed by single degree of freedom model. However, when mass and length ratio approach near one, a crane load motion greatly increase because a hook gives excitation to a load.

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This paper deals with a newly developed damper, called a keel damper, used to reduce bridge vibration caused by wind or vehicles passing over it. It was installed in two-girder bridge of span lengths 60m, and the vibration testing was carried out. The damping characteristic of the bridge was greatly improved by this damper. It was confirmed to have the high performance for not only first and but also second mode in which the frequency widely separated, moreover for minute vibration. As a result of investigating the temperature dependency of the performance, the characteristic agreed with the analysis comparatively well.

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In this study, a base isolation device using pseudoelastic shape memory alloy (SMA) wires is developed. A base isolation device using softening spring restricts acceleration transmission from the source of vibration so that pseudoelastic SMAs, which have origin-oriented hysteretic restoring forces, are utilized as softening springs rather than damping materials. Two SMA wires used in the spring are arranged as they are buckled when the spring are subjected to a load. Therefore, the spring's restoring force shows remarkable softening characteristic due to material and geometric nonlinearity. Furthermore, base isolation effect based on acceleration transmissibiliry is investigated experimentally and analytically.

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