本論文では,2つの柔軟リンクを有するマニピュレータに関して,有限変形に伴う幾何学的非線形性を考慮したモデルを構築し,実験と数値解析の両面から定量的な面からモデルの妥当性の検討を行う.

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In late years, the speedup of the calculation is necessary so that HILS (Hardware In the Loop Simulation) which combined simulation with an actual machine experiment attracts attention, and simulation with the real time is demanded. In this paper, I inspected a shortening effect in calculation time in the dynamic simulation of the flexible multibody system by the parallel processing using common memory of the Domain Decomposition Method (DDM).

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In this investigation, a gradient deficient beam element of the absolute nodal coordinate formulation is generalized to a curved beam for the analysis of multibody systems and the performance of the proposed element is discussed by comparing with the fully parameterized curved beam element and the classical large displacement beam element with incremental solution procedures. It is demonstrated by several numerical examples that the use of the proposed element leads to better element convergence as compared to that of the fully parameterized element when thin beam problems are considered. It is also important to note that fully parameterized elements are required for correctly describing of shear and cross-section deformations and such effect becomes significant when thick beams are considered.

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Two wheels which are connected by the flexible structure are on the pair of rail, is exited by the earthquake excitation. The seismic response of the flexible structure is significantly affected by the friction coefficient and the restitution coefficient. The modeling method for seismic simulation of the flexible structure under multi contact problem is developed with the unilateral contact. As the result, the effect of the transition between the static friction and the kinetic friction on the seismic response of the structure is discussed.

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In this investigation, dynamic characteristics of independently rotating wheel systems (IRW) are discussed. To this end, a multibody IRW model is developed using the method of velocity transformation. The linear stability analysis of a two-axle IRW truck is first performed, and the hunting stability and vibration characteristics of IRW truck are investigated and the results are compared with those obtained using the multibody dynamics model. It is presented that the longitudinal creep force is not ideally equal to zero in tight curve negotiation and special care need to be exercised when a simplified IRW model developed by specifying zero longitudinal creepages is used.

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In this paper, the calculation method of the equivalent creep coefficient in case there exist many contact points between a wheel tread and a rail was proposed. By using this proposed technique, the equivalent creep coefficient was estimated for the actual wheel profiles of the commuter train. The simulation was also carried out in order to find out how the difference a value of a evaluated creep coefficient until influence the running stability of railway vehicle. As a result, it was shown that it is important to calculate a creep coefficient strictly for evaluation of running stability of railway vehicle.

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Lateral forces between wheels and rails must be reduced in order that rolling stock runs safely and smoothly on curved tracks. Excessive lateral forces will cause not only derailment of rolling stocks but also destruction of tracks, rail corrugation, track irregularity, squeal noise and wear of wheel and rail. In this paper the authors study 2 methods to reduce lateral forces and improve running performance on curved tracks without development of new wheel profiles and bogie structures. According to the results of numerical simulation, the authors conclude that "expansion of gauge widening" and "increase of tie plate angle of inner rail", ie. "change of inner rail inclination", can get sufficient rolling radius difference and increase running performance on curved tracks. "Expansion of gauge widening" is effective both in "arc wheel profile for linear metro" and CS wheel profile, on the other hand, "increase of tie plate angle" is effective in "linear metro arc wheel profile".

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This paper presents measurement and analyses of wheel/rail contact geometry in tight curving. Examination of wheel/rail contact conditions is one of the most fundamental problems for railway vehicle dynamics. In this paper, basic experiments were made with an actual bogie and full scale test track. The lateral position and yaw angle of wheelset, and contact patch were measured in tight curve condition. These experimental results are compared with numerical calculations which are based on three-dimensional two-point contact analysis proposed by authors. It was found that there are good agreements in comparison between measurements and calculations.

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Recently, high speed elevators are strongly desired. But generally, it causes the increase of the deformation and vibration of the traveling cable. In a bad case, it collides with the side of the cage or facilities in the hoistway, but studies about the traveling cable are very few. In this paper, the analysis by multibody dynamics (MBD) is investigated. Temperature dependent parameters are identified and contact analysis of traveling cable with wall was effectively conducted by MBD.

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This paper presents a formulation for dynamics of unicycle systems with nonholonomic constraints using principle of interconnection. It is shown that Planck-Okada-Arsove's logic enables to derive kinematical and dynamical constraints for unicycle systems and also that a mathematical model of unicyle systems can be obtained by implicit port-Lagrangian systems, in which constraint force can be effectively eliminated by using dual connection matrices. Finally, we illustrate the validity of the present approach by numerical simulations of unicycle systems together with bond graph models.

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To determine mechanisms with respect to cause of thrust force of Tripod Constant Velocity Joint, we construct a detailed model based on multibody dynamics approach. Though the joint is equiped with three rollers, this model consists of some parts concerned with one roller. We verify this model by comparing the computational results with the experimental ones. By using this model, we evaluate that the main factors of cause of the thrust force are three types of sliding friction force with respect to one roller.

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As basic principles for deriving the equations of motion for dynamical systems, there are d'Alembert's principle and the principle of virtual power. From the former Hamilton's principle and Langage's equations are derived, which are powerful tool for deriving the equation of motion of mechanical systems since they can give the equations of motion from the scalar energy quantities. When Hamilton's principle is applied to nonholonomic systems, however, care has to be taken. In this paper, a unified approach for holonomic and nonholonomic systems is discussed based on the modified Hamilton's principle. In the present approach, constraints for both of the holonomic and nonholonomic systems are expressed in terms of time derivative of the position, and their variations are treated similarly to the principle of virtual power, i.e. time and position are fixed in operation with respect to the variations. The approach is applied to holonomic and simple nonholonomic systems.

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A positive displacement (PD) flowmeters has been used for long years as it can measure volumetric flow directly. Since features of PD's are most exerted in oil related flow measurements, in present society which environmental issues are emphasized, they are required for high accuracy fuel consumption measurements in transport equipment industry such as automotive industry, as well as assuming an important role in cross-border transactions. Also, in recent years, development of secondary standards for JCSS registration is an urgent need; verification of our Screw PD Flowmeter is made, corresponding to such necessity.

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This paper presents development of a system which measures a distance between two points in high places. The distance is calculated using 3-dimensional coordinates within each distance from measurement point measured by laser-sensor, and angles by an electrical pan-tilt unit. The device's accuracy is ±10mm per 10m at most. And more, the digital zoom-camera unit is attached to focus the measurement point semi-automatically. The camera unit makes it possible to take a photo of measurement target. A measurement results are stored as photos including the values of measurements. The upshot is improvement of efficiency at measuring and reliability of data.

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A non-contact micro-nano displacement system using interfere metric phenomena is proposed. This system vertically irradiates the laser light to two grating pairs with grating difference of 1/4 cycles. The relative displacement between gratings can be calculated from moire signal intensities detected by photodetectors. The results indicated that the resolution of displacement sensing mainly depends on the pitch of grating. And resolution of lOnm at 50μm pitch of grating is obtained in present system.

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The issues in dynamic load cell have been investigated based on the wave propagation model. It was revealed that the output value of the cell varies depending upon dynamic rigidities, i.e. boundary conditions, of the set up position. For the controversy about dynamic calibration method for load cells, it was disclosed by the experiments that static method of calibration is satisfactory for the column type load cells which usually employed in the measurement of dynamic loads.

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Rubber materials have been used for the relaxation of impact stresses on the collision of steel members. The use of rubber is considered to be very effective for the stress relaxation through investigations on the progressive wave between members, however, the inference does not take the influence of multiple reflections of the incidence wave in the rubber into consideration. This paper disclosed by employing a wave propagation model that the stress relaxation diminishes as the steel member becomes longer, and the results of the model were verified by collision experiments using Hopkinson bar.

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This paper describes an improvement for the measurement system of the road friction between a tire and road. The priciple of the measurement system is detecting the defference of the gradient of the relationship between the slip ratio of the tire and the acceralation of the car. When the road friction becomes low, the slip ratio changes larger about same deviation of accelaration. In this paper, we propose that the information of a GPS is used for the improvement for the measurement system. Sometime road has a slop and when the angle of the slope changes, the measurement system output has an error. The information of GPS may reduce this error. The experimental examination is verified this proposal.

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This paper is concerned with the active wave control of a rectangular panel. It is the purpose of this paper to present a wave filtering method for the panel using shaped smart sensors and its application to an adaptive feedforward control system. Firstly, the design procedure of the wave filter using shaped PVDF sensors is presented based on a wave solution of a rectangular panel. Next, from a viewpoint of numerical analysis, the performance of the control system are clarified. Finally, an experiment of the active wave feedforward control system is carried out, demonstrating the validity of the proposed method.

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A Bayesian framework for anomaly detection in monitoring data using the relevance vector machine (RVM) is developed. Actual monitoring data of building response including anomalous data obtained due to sensor malfunction and/or impacts of human activities are investigated. The most significant feature of the relevance vector machine is that a model class which has very sparse models in it is automatically selected by taking the automatic relevance determination (ARD) prior and maximizing the marginal likelihood, which is called evidence in the context of Bayesian model selection. The optimized RVM successfully classifies the data into the categories of normal and anomaly with extremely high reliability.

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This paper addresses a force identification hybrid approach by Matrix Inversion Method with use of moment of forces. It is very important to identify excitation forces because accuracy of Transfer Path Analysis (TPA) has been depending on identified force precision. The six-degree-of-freedom (6-DOF) excitation forces (three DOFs in translation and three DOFs in rotation) are obtained by using 6-DOF FRFs that are estimated by Rigid Block approach. This is a hybrid method that uses strain gauges and accelerometers for measuring responses in vibration testing.

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This paper concerns a structural health monitoring (SHM) methodology that can detect and characterize local structural damages in early stage, developed by combining the concepts of two existing SHM principles, a piezoelectric impedance-based methodology and a nonlinear wave modulation spectroscopy. When the structure is subjected to a dynamic load at low-frequencies, the nonlinear vibro-acoustic interaction between the low-frequency vibration and the high-frequency wave field in the vicinity of "contact-type" damages causes the change in the driving-point mobility at the high frequency range. Therefore, if the piezoelectric element bonded on the structural surface is driven by a fixed amplitude high-frequency harmonic voltage source, the nonlinear modulation of the coupled electro-mechanical admittance can be observed as the amplitude and phase modulation of the current flowing through the piezoelectric element. A simplified modeling study of this phenomenon successfully leads to a damage evaluation index that assesses the intensity of the modulation of the modal stiffness. Experiments using a cracked beam are conducted to see how the stiffness modulation can be observed and to examine the performance of the proposed method.

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Rotating machinery is widely used in the industrial plant, for example, power plant, chemical plant, mass-production plant and so on. In order to ensure safety operation of the rotating machinery, vibration condition monitoring of the machinery can play a crucial role. In the previous authors' study, the vibration energy harvester of the piezoelectric bimorph cantilever type was proposed for vibration condition monitoring applications of rotating machinery. Proposed energy harvester consists of Macro-Fiber Composite (MFC) which is flexible and durable piezocomposite type actuator. This study aims at presenting simulation model for proposed vibration energy harvester. Numerical simulation results indicate the power generation performance of the proposed vibration energy harvester.

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Performance of vibration suppression using piezoelectric elements is lower than that of mechanical vibration suppression methods. Usually piezoelectric elements are attached to target directly with adhesive bond, and to improve the performance, the size of the piezoelectric element must be larger, and it induces increase in cost. To solve this problem drastically, a new technique which improves the performance of piezoelectric elements by using spacers is proposed in this paper. The optimum height of the spacer is derived theoretically, and the effectiveness of the proposed method and theoretical analysis are validated by calculation and experiment.

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Energy consumption to drive actuator is thought as a disadvantage of active vibration control. However, the actuator of active vibration control system absorbs energy from vibrating structure to suppress the vibration. In other words, the actuator regenerates energy from the vibrating structure. Especially, piezoelectric actuator can regenerate energy effectively, because it has few internal energy loss. Recently, class D amplifier based on switching circuit has been utilized due to its high-efficiency. It can drive the actuator with few energy loss and regenerate energy from the actuator. Therefore, the energy regenerative active vibration control system can be realized by using the class D amplifier to drive the piezoelectric actuator. The validity of the system has been shown by numerical simulation. In this paper, a cantilever beam with the energy regenerative vibration control system is produced and power consumption of the class D amplifier and the piezoelectric actuator of the system is measured by electrical power meter to show the validity of the system experimentally. The result shows power consumption of the class D amplifier and the piezoelectric actuator is negative and energy of the vibrating beam is regenerated as electrical power.

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A virtual inductance is employed for the piezoelectric shunt damping. This paper discusses the quantitative analysis how the time constant of the approximate differentiator affects the damping performance. Two methods for designing the parameters are proposed, one is analytical and sub-optimal method, and the other is numerical and optimal method. The experimental results demonstrate the effectiveness of the designing the virtual inductance.

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In this study, a semi-active vibration suppression system comprising piezoelectric elements is developed for flexible structures. The vibration suppression system comprises a cantilevered beam with bimorph piezoelectric ceramic tiles shunted by a RL electrical circuit with a switching part. This study shows that the resonant shunt circuit functions as a type of a dynamic damper for mechanical systems and the proposed switching control, inspired by a sliding-mode control law, is more effective than the passive damping system especially for the multi-mode vibration suppression.

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This research addresses the optimized motion plans for the variable geometry truss (VGT) in order to avoid the resonant vibration while the VGT moves a target payload from one point to another as a space manipulator. The VGT has high redundancy and can change its shape variously. The natural frequency of the VGT is also changed by the geometry of the VGT. We assume that sinusoidal excitation force is generated by the payload such as trouble satellite during the manipulation, and it can cause the resonant vibration. It is shown that the otimized manipulation clearly reduces the amplitude of vibration by avoiding the resonant vibration.

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The subjects of this paper are a requirement clarification for a robotic structural matrials and a proposal of the new concept by the comparison with the conventional mechanical structural materials. Take into account a evaluation method for the flexibility on the bicycle structure, the evaluation method of robotic structural matrials properties is considered. Focusing on carbon nanotubes have excellent mechanical and electrical characteristics of both, the CNT/PVDF composite is tried to fabricate, and evaluated the characteristics of the sensor. The sensor characteristics of CNT/PVDF composite is used to change electrical resistance by the strain to occur from external load. The fabricated CNT/PVDF composite is compared some mechanical properties with the typical conventional mechanical structure. The possibility of CNT/PVDF composite is considered for a robotic structural materials. CNT/PVDF composite elastic modulus for 22.3 vol% CNT was the highest. The degree of elasticity has improved by about 40 % compared with PVDF. As a result of the measurement the electrical resistance by using composites with 5 wt% CNT, the rise and fall of the sensor signal was confirmed by the strain change.

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This paper proposes a remote control system for micro-vehicles with two-way laser communication technology. A pulsed laser tracking/control system and a laser communication system using a MEMS (Micro-Electric-Mechanical-Systems) mirror are integrated for constructing the two-way laser communication system. Utilization of the laser communication technology effectively achieves the miniaturization and lightening of the laser-driven micro-vehicles because laser has high directivity and it is possible to concentrate the power. In order to remotely control the vehicle, the vehicle position is transmitted to the base system from the vehicle by the laser communication system with MEMS mirror. At the same time, driving command for the vehicle is transmitted to the vehicle by the laser communication system with pulsed laser.

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著者らによって開発中の減衰係数可変の振動制御装置(VCD : Vibration Control Device)を用いて,セミアクティブ制御を前提とした建築構造物の統合化設計を行う.VCDは,図A1に示されるようなボールねじとフライホイールからなる機構に発電機を組み合わせた機構となっており,隣接層間の層間加速度に比例した慣性抵抗力と,層間速度に比例した減衰抵抗力の両者を発生可能である.発電機には,発電機内を流れる電流の大きさを外部指令電圧によって調整可能な電気回路が接続されており,指令信号電圧を変更する事により,VCDの減衰係数をリアルタイムに調整可能である.VCDの可変減衰機能を用いて,地震外乱による応答の予測値から計算できる評価指標を最適化するようなセミアクティブ制御系を構成する.このセミアクティブ制御を前提に,構造物の各層間の剛性分布と予測型制御を行う際に用いる重みを最適化する統合化設計を行い,地震外乱に対する振動制御性能の最適化を行う.実際の地震波に対する構造応答に基づいて統合化設計を行うため,過去に記録された地震波や,人工地震波を外乱とし,セミアクティブ制御を行ったときの応答出力を用いて性能評価を行う.最適化手法として,擬似焼きなまし(SA : Simulated annealing)法を採用する.

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An adaptive truss is a truss structural system having a number of length-adjustable members. It is one of the typical examples of so-called adaptive structure. We deal with a statically indeterminate adaptive truss having shape memory alloy (SMA) wires for its length-adjustable actuators. In the current study, we discuss the dynamic characteristics of such mechanical system. A piecewise linear model taking account of the nonlinear and hysteretic characteristics of a SMA wire is introduced. The equation of motion of the adaptive truss taking account of such SMA characteristics and a numerical integration technique based on the Newmark β method are developed. We also discuss the influence of properties specific to SMA, such as the hysteretic behavior, on the dynamic characteristics of the adaptive truss.

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In this study, a damage identification method for beam structures by separating and extracting guided wave is investigated. Especially in this paper, a spatial-frequency reflection intensity map which effectively displays the reflectivity at a specific location and frequency on a spatial-frequency plane is proposed. From this map, one can figure out the location of a structural discontinuity such as boundaries and damages, and read out the reflectivity at the discontinuity of interest as a function of frequency. An analytical study reveals that the reflection characteristics in a specific inspection area between the sensor location and one boundary can be accurately estimated when the excitation force is acting only between the sensor location and the opposite boundary, and the excitation force acting inside the inspection area may harm the estimation of the reflectivity.

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Many machine structures are used in various places, such as a car and a motorbike, including a factory or power plant. So breakdown, damage, etc. of a machine structure may not stop only at loss of a function depending on the scale or part, but may cause an accident resulting in injury or death and serious economic loss. Vibration is listed to one of the causes, which a machine structure breaks down and damages Therefore which needs to perform unusual diagnosis of a machine structure and needs to evaluate the soundness of a machine structure by always measuring affecting vibration to a machine structure, and carrying out monitoring to it. This research performs health monitoring to a machine structure using a small sensor and a PIC microcomputer, and aims at constructing the system, which performs mechanical predictive maintenance.

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Continuous operation of rotating machinery with a rotor crack is a risk condition since the rotor crack grows rapidly and may fail causing a catastrophic accident. This paper improves the concise and accurate finite element model of the rotating shaft with an open crack. The natural frequencies in the rotating condition and the resonance curves of the double-frequency vibration due to crack are investigated. Furthermore, the natural frequencies and the resonance curves of the experimental system are measured. By comparing both the theoretical and experimental results, the accuracy of the developed simple finite element model of the rotating shaft with an open crack and the theoretical analysis method discussed in this paper are confirmed.

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This paper introduces phenomena causing damaging torsional vibration of rotating machinery driven by Variable Speed Drive (VSD) Motor. Inter-harmonic frequencies contained in excitation torque generated by motor, because of its distinctive pattern, may coincide with natural frequencies of rotating machinery during operation even though the machinery was designed so that fundamental frequency and its harmonics can avoid coincidence with natural frequencies in the operating speed range. Torque of rotor shaft and output current of VSD were measured during product test. Quantitative guidelines for torque associated with sideband frequencies of VSD output current and modal damping ratio for VSD driven rotating machinery are proposed. Integrated mechanical (rotating machinery) and electrical (motor with VSD system) simulation was also conducted and its results were compared with measured data.

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An improved algorithm of recursive least squares (RLS) is presented. In order to prevent wind-up of RLS with exponential forgetting caused by lack of persistently excitation, various methods have been proposed in the past. One of the most popular methods is RLS with variable forgetting factor which regulates trace of covariance matrix to be constant. This paper proposes an improvement of the algorithm which avoids a problem of the conventional method on model instability which arises when d.c. bias of input signal is slowly varying, which is a common case of plant monitoring applications in systems affected by ambient temperature and/or humidity varying considerably slowly compared to plant dynamics.

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Today we live in a comfortable environment made by air-conditioning machine. But when it breaks down, we can't stay comfortable environment. In this study, to prevent the facility from breaking down we try to find a sign of a failure before it occurs. In failure diagnosis, we used nnet being a back-propagation (BP)-type neural network (NN) and SVM (Support Vector Machine) having characteristic of maximizing margin. However both SVM and nnet couldn't distinguish normal case from refrigerant leak case, SVM could assess more accurately the condition of the facility than nnet after simulation test.

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Device diagnostics for a heat utilization process, which is a typical bottoming process of distributed energy systems, is developed through a numerical analysis using a dynamic simulation model. In this diagnostics, monitored devices are grouped by temperature control loops, which are composed of a controller, a temperature transmitter, a control valve, and a heat exchanger, and the flow rate of circulating hot water is not measured to reduce the system cost. First, malfunctions of the devices in the monitored process are detected by comparing output process variables estimated by using an input-output characteristic model with measured output process variables; then, the device with the malfunction is identified by the pattern matching with the trend database of the process variables under typical device malfunctions, which was preliminarily constructed through a numerical simulation. The case study for a heat utilization process with two temperature control loops shows that this diagnostics without measuring the flow rate of the circulating hot water can identify not only the control loop with malfunction device but also the malfunction device in this loop.

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The paper introduces the new method to estimate vertical road roughness from accelerations and suspension strokes of the automobile using ICA (Independent Component Analysis), and examines the performance through the numerical simulation. The authors propose to apply ICA to monitor the automobiles. ICA only presumes the independency of source signals, so it is expected that ICA can identify the road roughness without specifications of a car. To simplify the discussion, only vertical and pitch motions are considered. The integral of strokes, velocities, and differential accelerations are calculated by integrating and differentiating the measured accelerations and suspensions strokes, respectively. They are treated as parts of the observed data sets as well as the accelerations. By using ICA, the similar shape to the input road is estimated.

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Although the wear of contact wire is one of the most important problems for maintenance of an overhead catenary system, the wear mechanism of the contact wire is very complicated, and many unsolved problems still exist. The authors are studying in the quantitative effect of the pantograph contact force and the arc due to contact loss on the contact wire wear. For this purpose, the authors have developed a method, by which contact forces of all pantographs measurable during passing on sections where sensors are installed on the catenary. The method is effective in monitoring the behaviors of the pantograph. The authors have measured the contact forces and arcs on the line test. In this paper, the authors have reported the results of measuring the contact force on the line test. This result has indicated that the foregoing measurement method with sensors on catenary is properly valid.

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This study deal with nonlinear dynamics of a horizontally supported Jffcott rotor. When the rotational speed of the rotor is in the neighborhood of twice the natural frequency, it is expected that 1/2-order subharmonic resonance can be produced. By applying the method of multiple scales to the dimensionless equations of motions, we describe the linear unstable region which corresponds to the bifurcation set of sub-harmonic resonance and theoretically predict the occurence. Furthermore, using a simple apparatus, we experimentally confirm the prediction and clarify the nonlinear characteristics of the frequency response curve. While the frequency responce curve is hard-spring type in the case of the lower resonance in the lateral direction, it is soft-spring type in the case of the higher one. These nonlineaer characteristics correspond to those of the backbone curves clarified in the previous study.

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The use of the wind turbine generator has rapidly spread as the one of the clean energy sources. Recently, as the size of the wind turbine generator becomes larger, its maintenance becomes more difficult. However, there are few studies on the vibration analysis and its suppression in the conventional researches. The wind turbine is a special type of rotating machinery which has a long heavy blade rotating in the vertical plane under the action of the gravitational force. The wind power acting on the turbine blade changes periodically because of the height-dependent characteristic of the wind power. Therefore, the wind turbine blade requires the original point of view in the dynamical analysis. This paper investigates the fundamental vibration characteristic of the elastic wind turbine blade. The nonlinear analysis of the super-harmonic resonance is performed, and its characteristics are explained. Furthermore, the interaction effect of gravitational force and wind force on the super-harmonic resonance is clarified.

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This paper examines the accuracy of analytical solutions for nonlinear vibration analyses of continuous systems with quadratic and cubic non-linearites. As an example, we treat a suspended homogenous elastic cable whose two supports are fixed, and investigate the primary resonance of the second (first antisymmetric) in-plane mode (Ω=ω_2), in which Ω and ω_2 are the driving and natural frequencies, respectively. The steady-state responses are found by using two different approaches. In the first approach, the method of multiple scales is applied directly to the governing equation that is a nonlinear partial differential equation (direct approach). In the second approach, we discretize the governing equation by using Galerkin's procedure and then apply the method of multiple scales to the obtained ordinary differential equations (discretization approach). In the discretization approach, the detuning parameter σ, which expresses the relationship between the natural frequency and the driving frequency, is change from Ω=ω_ + εσ to Ω_2 = ω^2_2 + εσ so as to improve the accuracy of the solutions. In order to check the validity of the solutions obtained by the two approaches, they are compared with the solutions obtained by the finite difference method.

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In the previous studies, a method to construct a rational reduction model for a large-scale nonlinear structure having locally nonlinearities was proposed. In this study, the method of harmonic balance is applied to the reduction model to introduce the efficient computational technique for obtaining the steady-state vibration. By applying the harmonic balance method, the correctional quantities at modal coordinates of the reduction model can be computed from small size matrix computation at high-speed, and the correctional quantities at physical coordinates can be computed efficiently by recursive computation process using small size matrices. The effectiveness of these computational techniques is investigated from various computational results. Additionally, deciding method of the order of Fourier series for an approximate solution is investigated from view points of accuracy of solutions.

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With a conventional ultrasonic inspection, it is difficult to detect an obscure crack which does not show an indistinct reflection. In this paper, we regard the supersonic wave as an oscillatory waveform and detect the minute abnormality by means of the slight modulation of the supersonic frequency. In the experiment, we use rubber plates to make an obscure crack because of its manageability. A new technique is employed to evaluate the frequency modulation of supersonic wave. A significant difference is observed in the supersonic frequency by means of the proposed method.

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This paper studies flow-induced vibration of a circular cylinder in a cross flow. The cylinder is supported by two pairs of elastic cantilever beams and a wire that adds nonlinearity to the system. A pair of electromagnets is used as a device of external force. Nonlinearity of the restoring force is identified by using experimental data and mathematical model is established. Time history response of the vortex-induced vibration is measured experimentally. The time-frequency analysis is employed to the signal, and characteristics of the fluid-structure nonlinear coupled vibration are clearly observed. Theoretical analysis of fluid-structure system is attempted by using the wake oscillator represented by Van der Pol equation. Simulation results show the typical tendency of nonlinearity in the experiments.

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Analytical results are presented on nonlinear coupled vibrations of a system of a rigid rod supported by parallel strings. Nonlinear periodic responses are calculated with the harmonic balance method. Time responses of the system are calculated by direct numerical integration with the Runge-Kutta method. As the excitation frequency is increased, vibration form changes from in-plane periodic vibration to whirling, and then quasi-periodic responses appear accompanied by whirling and pitching motion. At the specific frequencies in the region of quasi-periodic responses, chaotic responses are also observed. As the excitation frequency is increased further, the vibration form transits to periodic pitching vibration with the jump phenomenon. It is found that the frequency region of the quasi-periodic response is narrowed as the eccentricity of the rod is increased. Furthermore, the region of the quasi-periodic response is slightly enlarged by the increase of the distance between the two strings.

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Squeal and chatter phenomena were generated in bicycle disc brake. In this report, the authors deal analytically with a simple coupled in-plane and out-of-plane vibration system with three degree of freedom subject to the friction in order to make clear the essence of such phenomena generated in bicycle disc brake system. In this model, two kinds of squeal were also generated in the nonlinear analysis, and the squeal generated in the linear analysis and the internal resonance phenomena were also generated in the nonlinear analysis. The squeal was in-plane unstable vibration in the disc surface direction, caused by the dry friction with negative slope with respect to the relative velocity. The internal resonance phenomena, that is, the chatter was the other frictional nonlinear vibration in which the squeal and the out-of-plane unstable vibration due to Coulomb friction were combine together through the internal resonance relationship between out-of-plane and in-plane vibrations caused by increasing of moment spring constant.

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Squeal and chatter phenomena were generated in a bicycle disc brake. The squeal was in-plane unstable vibration in the direction of the disc surface, caused by the dry friction with negative slope with respect to the relative velocity generated in the vibrating system including brake unit, spokes and hub. According to the experiments, the chatter was generated in a certain limited range of high temperature, and was the other frictional nonlinear vibration in which the squeal and the out-of-plane unstable vibration of the disc due to Coulomb friction were combined together through the internal resonance relationship between out-of- plane and in-plane vibrations caused by the temperature increase of the disc during braking. This paper deals analytically with the generation mechanism and the criterion of whether or not the squeal occurs, then they determine numerically whether the chatter occurs in a bicycle disc brake in terms of the nonlinear analysis.

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