In this paper, the double layered or triple layered piezoelectric pump is rationally designed for the purpose of more pump performance improvement. In the experiment, discharge rate characteristics of piezoelectric pump are investigated. In order to attempt the theoretical prediction of discharge rate, the deflection curve of PZT vibrator is examined. Experimental results show that the maximum discharge rates were increased than the single layer pump. And, in the case of driving in low frequency, the vibration displacement of PZT vibrator was approximated as the deflection curve, which calculated simplified theoretical model.

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The out-of-plane deformation of the roof-deck caused by the radial second mode of sloshing results in radial contraction of the deck, thereby inducing an elliptical deformation of the pontoon. In this paper, the stress caused by this elliptical deformation is analyzed. Numerical results show that the bending stresses are magnified locally near the joint with the deck. A method of reducing the circumferential membrane stress in outer portions of the pontoon is discussed.

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Dealing with car frontal crash, previous research has indicated that front side member plays major role in energy absorption. For protecting the passengers, the front side member is expected to absorb crash energy as much as possible. In this study, the front side member with half cut type is studied by parameter study and optimum design method. An optimal design system of the half cut type side member is developed, in which the objective function is to maximize the absorbed energy of side member structure; the design variables are structural parameters, number of edges of polygonal cross section; spot welding pitch length; and thickness of thin-walled side member structure; the constrained condition is that the mass of optimal side member must be less than the allowed value. The parameter study and optimum design results are then discussed. The effect of absorbed energy with each design variable is studied. And the optimal side member structure is capable of absorbing energy 17.01% more than that of original half cut type of box-shaped cross sectional side member structure which is generally used.

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All car manufacturers are recently required to develop the engine-hood for the purpose of protecting pedestrian heads. The engine-hood is evaluated by the pedestrian head protection performance test according to the HIC. It is important to control the acceleration time history at the initial stage and late stage for pedestrian head protection. This study also aimed to evaluate that impact characteristics of inner panels adopting corrugated panels improve pedestrian head protection by numerical analysis. As a result, the corrugated panel structure helped control the amount of displacement and it was effective in reduction of HIC.

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The 2003 Tokachi-Oki earthquake caused severe damage to oil storage tanks due to liquid sloshing. Seven single-deck floating roofs had experienced structural problems as evidenced by sinking failure in large diameter tanks at the refinery in Tomakomai, Japan. The pontoons of the floating roofs might be buckled due to bending load during the sloshing. The initial geometrical imperfection may diminish the buckling load of the pontoon. This paper presents the lower bound buckling load of the pontoons based on the reduced stiffness method proposed by Croll and Yamada. The axisymmetric shell finite element method is used in the linear elastic bifurcation buckling analysis.

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The finite element method is applied to the buckling analysis of laminated composite shells of revolutiion. The axisymmetric shell elements are used and the displacement field within each element is represented by Fourier circumferential components. The buckling analyses are performed for the composite cylindrical and conical shells under axial compression. The validity of concept of equivalent cylindrical shells for the buckling analysis of conical shells is investigated.

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Advanced fiber-reinforced laminated composite materials have been used as structural members in various fields because of their high strength and high stiffness-to-weight ratios, and hence analysis of thin laminated structures is important. In this paper, secondary buckling strength of composite laminated curved plates under biaxial compressive loads which are simply supported along four edges is determined, using the second variation of total potential energy. The necessity of secondary buckling is proven analytically, and the effects of various factors, such as shape parameter, lamination constitution, and biaxial compressive loads, are clarified.

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In this paper, we regard the ultrasonic wave as an oscillatory waveform and detect the minute degradation by means of the slight modulation of the ultrasonic frequency. In the experiment, we use epoxy resin adhesive which bonds two acrylic plates and detect the defect in adhesion. A new technique is employed to evaluate the frequency modulation of ultrasonic wave. A significant difference is observed in the ultrasonic frequency by means of the proposed method. By simulation, the cause of the observed difference is made known.

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This study investigates an identification method for physical parameters and vibration modes of beams. A robot arm is used to swing the beam, and input-output data of swinging trials are measured. In this method, physical parameters of the beams are identified by least-square method, and vibration modes are derived by finite element method (FEM), iteratively. Vibration modes of the beam are necessary to estimate actual physical parameters such as stiffness, El, and density, pA, of the beam. Temporary physical parameters are applied to assume temporary vibration modes for the initial condition of iterative calculation. Reliability of proposed identification method is confirmed by numerical simulations.

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For the structure of the motor, it repeats fine acceleration and deceleration such as in a constant speed. Because of this, it would cause revolution fluctuation and vibratory forces. The vibratory forces of the motor cause the vibration and the noise. In order to measure the vibratory forces, the rigid-body vibration needs to be measured, and we make the motor to be free support. However, depending on the size of the motor, it is difficult to make it be free support. In this study, we formulate a way to measure the vibratory forces of motor without free support and aims to establish it through experiments. In this measurement method which was invented, there is a possibility for practical use.

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Stochastic jump phenomena in the random responses of a Duffing oscillator subjected to narrow band excitation are investigated. The stochastic jump phenomena correspond to the existence of multiple stationary responses, which differ in phase angle to the excitation. In this paper, the product of complex wavelet transform of the response and the complex conjugate of that of the excitation is used to evaluate phase angle of each frequency. Numerical examples show that the product successfully identifies two states of the response, as well as the previously proposed criterion using real wavelet transform.

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The non-Gaussian response characteristics of a non-symmetric nonlinear 1-DOF system subjected to non-white excitation are investigated. Applying a previously-developed method, which contains the Non-Gaussian equivalent linearization technique and the use of the moment equations approach, the stationary responses are calculated. Skewness, Kurtosis, and equivalent linear coefficients are demonstrated as the maps of the non-Gaussianity. These show the effects of the non-symmetric properties of the system and the dominant frequencies of excitation upon the non-Gaussian response characteristics. The illustration also shows the relationship between the resonance of the system and the non-Gaussian response.

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When the system is subjected to excess vibrational load, the response is beyond yield point. In this case, restoring force has hysteresis loop characteristic. It is well known that the response is reduced due to absorbed energy by hysteresis loop characteristic caused by plastic deformation. However, strength of the system degrades owing to accumulated energy. In this paper, relation between accumulated energy by hysteresis loop characteristic and reduction of the maximum response is examined. The system is modeled as a single-degree-of-freedom system and subjected to filtered white noise. Assessing method for relation between degradation of the system and the maximum response is shown.

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In this study, we measured transfer functions of a bicycle at various experimental conditions by performing a hammering test and measured vibration at running for considering a suitable hammering test condition. In the tests, we focused difference of resonance frequency of a bicycle frame with driver and that without driver. As results, the transfer function measured at hanging the bicycle using a rubber tube (without driver) shows clear resonance peak and the frequency was almost same at that at running test (with driver). Therefore, hanging bicycle without driver was clarified to be suitable experimental condition for a hammering test.

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This paper deals experimentally and analytically with the design of a dynamic absorber to quench galloping phenomena generated in transmission lines in the condition of storong wind. Galloping phenomena are one of self-excited vibration called flow-induced vibration, and it is caused by a hydrodynamic coefficient obtained from lift force and drag having a negative damping. As a countermeasure, a dynamic absorber was experimentally applied to a simple experimental test rig composed of the main system supported by four springs. And, the simple analytical model of galloping was set up. The dynamic absorber was applied also analytically. It was found by the experiments and analysis that the natural frequency of the dynamic absorber should be tuned near the galloping frequency and the optimum damping of the dynamic absorber exists to quench the galloping. These results qualitatively agreed with experimentally and analytically.

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A diesel engine is mainly used to commercial vehicles from the viewpoint of fuel economy. But its exciting force is larger than that of petrol engine, which causes the uncomfortable vibration at an idling revolution. Therefore, in this study, an air spring is newly applied to the actual engine mount system of a medium duty truck and many vehicle tests are conducted for checking its vibration isolation effect and its big displacement caused by engine shock torque. As a result, the significant vibration isolation effect could be not only obtained, but the big displacement was within the limit.

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This paper presents a novel vibration control technique for a pendulum via cable-length manipulation. First of all, we derive the equations of motion for a pendulum with variable cable-length. In order to control the sway angle by using the reeling and unreeling of the hosting cable, we adopt a nonlinear feedback control in which a parametric resonance phenomenon is utilized. The feedback gains are determine by use of a particle swarm optimization so as to reduce as much as possible the sway angle. The ability of the proposed control technique is confirmed by numerical simulations. Furthermore, the realization and effectiveness of the present approach are verified by experiments.

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This paper deals with collision vibration in continuous system excited by periodic displacement with arbitrary functions. The analytical model is steady collision vibration in simply-supported-beam having an attached mass which collides elastically to symmetric faces with restoring force of hysteresis loops. In order to clarify the main resonance of the system subjected to excitation by displacement, the resulting vibration is analyzed applying the Fourier series method for this system. Following this theoretical analysis, the numerical calculations are performed, and the resonance curves are constructed 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.

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Authors have been examining the restitution property of the steel ball of the same diameter and the same mass to understand the impact phenomenon of the solid bodies. As the simplest case, the impact experiment and the finite element analysis were conducted for two spherical bodies subjected to collide repeatedly with the same position at the same speed. The experimental results are compared to the analytical results obtained by Finite Element Analyses, and they showed the same tendency.

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Impact vibration of beam that has very narrow clearance between beam and impact wall, and that is excited around 2nd natural frequency, was investigated and the followings are made clear. (1) The beam is weakly resonant if excitation frequency is nearly equal to even number times the 1st natural frequency. (2) Even if the excitation frequency is nearly equal to the 2nd natural frequency, the beam is not resonant because 1st mode is dominant the vibration. (3) Those are caused by asymmetric property of the system. Furthermore, the beam is strongly resonant at non natural frequency.

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When we take pictures with continuous shots with single lens reflex camera, the inner mirror must repeats to go down and up with very high-speed. In this operation, the mirror hits to a stopper and rebound instantaneously. We investigate the rebound characteristics of the mirror model with free fall testing. Rebound angle of the model is varying by the stopper position. In the experiments, we find the stopper position which has lower amount of rebound angle. And the experimental modal analysis is carried out for the mirror model.

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Squeal is often generated in car disk brakes. There are several kinds of squeals, called high frequency squeal and low frequency squeal. Both squeals are distinguished by their squeal frequency range and their vibration mode. The high frequency squeal is the coupled vibration between the pads and the rotor, and low frequency squeal is the coupled vibration between the caliper and the rotor. Recently, new kind of car disk brake squeal which is in-plane vibration in the direction of the rotor surface becomes a serious problem in this field. Several investigations were conducted to analyze the mechanisms of the in-plane squeal. However, the mechanism of in-plane squeal has not been clarified, yet. In this paper, several experiments and theoretical analyses using simple three degree-of-freedom system were conducted to analyze the mechanism of the in-plane squeal.

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In the torque converter of the automatic transmission car, the mechanism of lock-up clutch that improves fuel cost is used. However, the shudder vibration sometimes occurs. The shudder vibration is a torsional vibration, and is caused by the friction at the lock-up clutch. When the shudder vibration occurs, the tires vibrate in the torsional direction which leads to the vibration of the car. Therefore, the shudder disturbs the comfort for the passengers. In this report, the mechanism of the shudder was clarified by the experiment and theoretical analysis, and the countermeasure using the dynamic absorber is also analyzed. The results of the experiments qualitatively coincide with those of the numerical analysis.

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This study presents the experimental and analytical results of tests on the influence of pad contact stiffness on disk-brake squeal. Pads with different surface textures and thicknesses were prepared, and the frictional interface texture under compressive load was measured. Correlations between the dynamic stiffness and the texture of the brake pad surface were examined. We used a surface-contact model to analyze the generation of squeal, which is caused by pad surface texture.

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Disk brake squeal depend on the pressure for brake. It is necessary to clarify the cause of the pressure dependency of squeal to prevent squeal effectively. The past researches clarified that the pressure dependency of the dynamic stiffness of brake pad is a cause of the pressure dependency of squeal and squeal generation. In this study, the relation between the vibration mode of brake disk and sound pressure level of squeal is measured. And the mechanism of squeal generation is examined using an analytical model of three degree of freedom.

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We studied that the influence of a coupling element, which connects some nonlinear self-excited oscillators, on the self-synchronized phenomena. In this report, the model composed of two oscillators and a coupling element is investigated by applying the improved shooting method. As a result, in comparison with the previous model where two oscillators are directly coupled by a coil-spring and a dashpot, the self-synchronized phenomena widely occur against the considerable individual variability according to the parameter of the coupling element. In addition, the relation between the natural frequencies of the whole system and that of coupling element is also investigated in order to consider the reason why the phenomenon widely occurs.

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When the agricultural machines run on pavement, the vibration and the noise caused by interaction between the tire lugs and the road surface are inevitable. In this study, the test equipment is manufactured to determine the motion of a rolling agricultural tire with ground contact and the characteristics of motion for rotational speed are investigated. Next, natural frequencies and natural modes of the tire are obtained by caning out experimental modal analysis. By using the obtained results, the influence of vibration characteristics on the dynamic behavior of rolling tires are investigated.

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Synchronized vibration of lifts appears in cableway structures and has the possibility to lead to a serious accident. The purpose of this study is to analyze the vibration characteristics causing the synchronization. In this study, to construct a model of the coupled vibration of a rope and lifts, the rope was divided into multiple equivalent mass and spring elements and lifts were modeled as pendulums. Numerical analysis implies that energy of the system can concentrate in one of the lifts depending on initial phase conditions of the lifts and the vibration can become large.

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Based on the finite element method, a new analytical procedure on free flexural vibrations of a stepped beam is presented. In this analysis, the stepped beam is divided roughly into the segments with different cross section. The mode shape function proposed by senior author is introduced to discretized equation derived by the Galerkin procedure. This function expressed by the product of the truncated power series and the trigonometric function is continuously differentiable. The continuity conditions of deflection, slope, bending moment, and shear force are satisfied in the nodes of each segment. We call the name of this procedure as the Finite Segment Analysis. The natural frequencies of a straight beam are analyzed, and the accuracy of the numerical procedure is discussed. Changing dimensions of the stepped beam, the natural frequencies and the natural modes of vibration are compared. Accurate results of natural frequencies and the natural modes of vibration are obtained with a small number of segments.

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In this paper, a theoretical solution of forced vibration of an axially moving string, whose length is constant, is presented. Finite difference analyses of string vibration are also performed to verify the validity of this solution and to obtain the vibration characteristics of moving string. The calculated results of the finite difference analyses are in fairly good agreement with that of the theoretical solution. The effect of the moving speed on the resonant frequency and the anti-resonant frequency is clarified in the case of both ends are exited sinusoidally.

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In this paper, we discuss the contact behavior between the stator and the lining material that sticks to the rotor of an ultrasonic motor. The ultrasonic motor is powered by the vibration of the stator and operates with a frictional force between the stator and the lining material. Therefore it is important to examine the mechanism of the contact behavior to improve the energy efficiency and durability of the ultrasonic motor. We propose a numerical technique using the finite element method on the basis of incremental theory to examine the contact behavior. Moreover, we clear the contact mechanism and the driving characteristics of the ultrasonic motor.

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Nonlinear behavior of pipe conveying fluid is significant in the field of engineering and industry. Curved pipe conveying fluid which is hanging horizontally and is supported at both ends is excited at fluid velocity having a small pulsating component. Under a frequency region of pulsating component, curved pipe behaves spatially. In this study, it is theoretically and experimentally clarified that the phenomena is caused from forced vibration at in-plane, and also from nonlinear coupling between the in-plane and out-of-plane motions.

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We are studying a new analysis method for transient responses by using the digital filter. This paper demonstrates some time-frequency analysis results of responses based on typical differential equations. First, we present the results for the linear free and forced vibration responses of one degree-of-freedom system. Then we consider the responses based on Duffing's equation and it is shown that the dominant frequency change of the responses can be visualized in the time-frequency analysis results. And the responses based on Van del Pol and Mathieu equations are analyzed to understand the several dominant frequencies. Finally, we apply the time-frequency analysis to the data of car bumping and it is shown that the phenomena may be described by the Duffing's equation.

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This paper studies dynamic behavior of driving belt system with periodic stiffness. we make a motion equation by the Lagrange equation. It is numerically shown the bifurcation diagram and the resonance diagram. we show the period-doubling bifurcation by the bifurcation diagram, and its trajectory.

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Nonlinear vibrations of an elastic structure, with a nearly square liquid tank, under vertical harmonic excitation are investigated. When the tuning condition, a ratio 2:1:1, is satisfied among the natural frequencies of the structure and two sloshing modes (1, 0) and (0, 1), the equation of motion for the structure and the modal equations for sloshing are derived considering the nonlinearity of sloshing. Then, van der Pol's method is employed to determine the frequency response curves. The effectiveness of a square liquid tank as a tuned liquid damper is shown by investigating the influences of the system parameters on the frequency response curves.

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Analytical results are presented on chaotic vibrations of a post-buckled beam constrained by an axial spring under axial and lateral excitations. Equations of motion of the beam are derived including the term of parametric excitation due to the axial excitation. Nonlinear periodic responses are calculated with the harmonic balance method. Time progress of the beam, including chaotic response, is calculated with numerical integration. Effects of the amplitude and phase of the axial excitation are examined on the nonlinear periodic responses and the chaotic responses of the beam. Amplitude of nonlinear periodic responses and width of frequency region where chaotic responses are generated deeply depend on the phase difference between the dynamic response of the beam and the axial excitation.

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Vibration with a low frequency sometimes occurs in a vibro-impact system. The characteristics of the vibration are similar to those of the self-excited vibration. Therefore, this paper regards such a vibration as the self-excited vibration in a vibro-impact system, and investigates experimentally effects of some parameters on the vibration. The experimental apparatus consists of two rigid bars, one of which is excited by an unbalanced mass. The results show that the self-excited vibration occurs when the exciting frequency, unbalanced mass and constant of restitution are large. In particular, the vibration occurs clearly, that is, the natural frequency appears clearly, when the constant of restitution is small.

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We study periodic grazing impact of some specific multi-vibro-impact oscillators which inherent Grover wave algorithm. Periodic energy transfer is caused from the internal resonance between the globally coupled impact and non-impact small oscillators. Impact small oscillator that can lose kinetic energy from the energy transfer to pragmatize grazing impact near the zero velocity. We derived the condition of perfect zero velocity graze impact by using wave algorithm. Trace of impact map in Bloch sphere shows figure of eight orbit, which corresponds to the switch of two different impact modes at the graze impact.

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A theoretical and experimental investigation was conducted into impact oscillations between a panto-graph and an overhead rigid conductor line in a railway current system. The contact problem was modeled as impact oscillations of an intermediate spring-supported beam excited by an oscillating plate. First, the impact oscillations of a beam with a sinusoidal vibrating plate were theoretically examined. The impact relations are derived considering the effects of multiple modes vibrations. Using some of the concepts behind periodic oscillations, qualitatively distinct impact oscillations of the beam with multiple modes are clarified. The interactions between the lowest two modes during the impacts are also discussed. Moreover, we conducted an experiment using a similar model based on the analytical model. Qualitative agreement was demonstrated between the experimental and theoretical results. Some experimental results reveal specific impact oscillations which correspond to the theoretical results considering the interactions between lowest two mode vibrations.

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Chaotic vibration occurs in various mechanical systems such as shell structures, subsoilers for agricultural machinery, gear box, and so on. In this paper, we examine the chaotic vibrations under influence of periodical impact forces experimentally. Our experimental setup is a steel beam pulled by two magnets, which has two stable steady-state equilibrium. As a results, the periodical impact forces can change chaotic vibration on our setup to the periodic vibration in a case where the chaotic vibration includes high frequency component of external force.

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This paper is aimed for elucidation of the mechanism of synchronized phenomenon between two small oscillators coupled with one big oscillator. We confirmed the synchronized phenomenon by numerical simulation for the collision system without damping. In addition, we attempted to model and analyze the synchronized phenomenon by using transition matrix. We defined two operators, time evolution operator and impact operator, and clarified the role of those operators. The time evolution operator changes energy of oscillators in response to phase difference of oscillators. The impact operator changes phase difference of two small oscillators in response to energy of small oscillator.

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The authers have developed an synchronous vibration mechanism for a tamping rammer in order to reduce the vibration propagated through the human body. In this paper, the self-synchronized phenomena generated in the impact model with two oscillators are investigated experimentally and analytically. The results confirmed that the self-synchronized phenomena for achieving a good balance between vibration control and excitation can be generated. It is also proven that expanding the existence region of the beneficial self-synchronized solutions and eradicating the existence region of the unnecessary stable self-synchronized solutions can be accomplished concurrently by setting the system parameter appropriately.

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The purpose of this research is to develop a synchronous vibration mechanism in order to reduce the hand-transmitted vibration. In this paper, the synchronized phenomena generated in the impact model with four oscillators are examined experimentally and analytically. The analytical results agree well with the experimental results quantitatively. The results confirmed that the synchronized vibration for achieving a good balance between vibration control and excitation can be occurred, and that setting the system parameter appropriately enable to easy to generate the suitable synchronized vibration.

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We demonstrate the usefulness and validity of the subharmonic Melnikov method for bi- and trilinear oscillators in piecewise-smooth systems. Special attention is paid to degenerate resonance behavior. Analytical results are also illustrated by numerical ones via the computer software AUTO97.

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Flexible structure, such as beam or thin plate, would be unstable for some external forces. For example, in-plane excitation causes parametric resonance, and out of plane excitation causes forced resonance. In this study, dynamics of both horizontally and vertically excited slender cantilever beam was analyzed. The beam is assumed inextensible Euler-Bernoulli beam. Governing equation of motion has nonlinear elastic term and nonlinear inertia term. Applying Galerkin's method for the first bending mode, forced Mathieu's equation is derived. Frequency response is obtained by harmonic balance method, and its stability is investigated by phase plane method.

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A rational method of dimensional reduction is developed in order to analyze accurately a nonlinear vibration of a large-scale system with nonlinearity. Almost nodes without strongly nonlinear excitation are transformed into the modal coordinates. And a small number of modes whose effect on computation accuracy of the vibration analysis is significant are extracted. On the other hand, the remaining modes are appropriately approximated and are eliminated. The low-dimensional model is constructed by these procedures. Furthermore, by applying an efficient method to eliminate higher-order modes, the low-dimensional model is constructed without computation of higher-order eigen pairs. Effectiveness of this method is verified by computational result.

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The vibratory characteristics of multiple nonlinear beams attached to elastic structures under harmonic excitation are investigated. Van del Pol's method is used to determine the resonance curves. It is found that a part of resonance curves, which are stable in a system with one nonlinear beam, change to be unstable and that five branches for steady state solutions may appear. The beams vibrate in different amplitudes. This means "localization phenomena." The system may encounter fold bifurcations and Hopf bifurcations depending on the values of the system parameters. Amplitude modulated motions, including chaotic vibrations, are observed in the numerical simulation.

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Recently, wiping performance simulation and theoretical analysis of a wiper is desired to streamline the development of it. This research aims to describe the dynamics of the reversal behavior of the wiper blade. First, the experiment with the cut model of actual blade rubber was conducted to observe the reversal behavior of wiper blade. To theoretically identify the mechanism, governing equations are derived from the analytical model of wiper blade which consists of a rigid bar. Bifurcation produced in the reversal behavior is discussed with the equation of equilibrium focusing on the friction acting the rubber.

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Experimental results are presented on chaotic vibrations of a locally stepped beam constrained to axial compression. One end of the beam is clamped and the other end is simply-supported. The simply-supported end is elastically compressed by an axial spring. The dynamic responses of the beam are measured under lateral periodic acceleration. In typical frequency ranges, non-periodic responses are observed. The responses are examined by the Fourier spectra, the Poincare maps, the maximum Lyapunov exponents and the principal component analysis. The responses are found to be chaotic responses. In a specific axial compression of the post-buckled beam, the chaotic vibrations with dynamic snap-through phenomena are generated closed to the sub-harmonic resonance response of 1/2 order of the fundamental mode of vibration.

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Experimental results are presented on nonlinear vibrations of a plate carrying a concentrated mass with mixed boundary of rectangular and circular shapes. The plate with the mixed boundary is simply supported for deflection. Under periodic lateral excitation, chaotic responses are obtained in a specific frequency region. The chaotic responses are examined with the Fourier spectra and the maximum Lyapunov exponents. Applying the principal component analysis, contribution ratio of each vibration mode is clarified. It is found that chaotic responses of the plate without the concentrated mass are generated from the internal resonant response between the lowest and sixth modes. With the concentrated mass, chaotic responses are generated from the combination resonant response between the lowest and fourth modes of vibration. Increasing the concentrated mass, time variation of contribution ratio corresponding to each vibration mode becomes small.

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