In this paper, stability on the polygonal deformation phenomena in BTA deep hole drilling is analytically investigated. The phenomena is modeled as a time delay system accompanied by cutting in which the amount of cutting on the workpiece is fed back as forced displacement. The authors focused on the condition of contact between the tool guide-pads and workpiece. According to the results considering the line contact and the distributed contact of the tool guide-pads, it is confirmed that system becomes more stable as the polygonal number is high in case the contact state is the distributed contact.

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In this paper, we design a flight controller for a twin-rotor helicopter model with considering actuator constraints. The controller is composed of the state dependent gain-scheduled feedback control law and the reference management device which are adjusted optimally by on-line computation. We show that the control system with the proposed control law achieves higher tracking performance as compared to the system with the standard constant feedback control law through experimental results.

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This paper deals with an experimental study on the effect of the phase relationship between fore wings and hind wings of tandem flexible flapping wings. A flapping mechanism of tandem flexible wings is developed in this study. And a self-excited driving system using frequency entrainment is applied to this mechanism. This driving system synchronizes the motion of fore wings and hind wings. The propulsion force generated by the tandem flapping wings is measured using a high-sensitive force sensor, and the performance of the propulsion force is clarified experimentally.

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This paper proposes a pulsed laser tracking, control, and energy transmission system to realize remote control for micro-vehicles. Such systems have been attracting the attentions of engineers because of their smallness and energy saving potential. Remote control of vehicles is realized by sending the information for motor actuation using a pulsed laser. The same laser tracks the vehicle motion. A second, high-power laser transmits energy to a photoelectric conversion element attached to the vehicle. An optical device is proposed that integrates the two systems without interference. A prototype system was developed and its performance was confirmed experimentally.

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This paper solves the stabilization problem for a flexible beam with both ends free using a boundary control technique. The boundary controller is designed according to the standard method for designing passivity-based controllers. For set point problems, the potential energy shaping that assigns the desired configuration to an equilibrium point of the closed-loop system is sufficient. The potential energy shaping is therefore completed by adding the artificial potential energy that specifies the displacement of the both ends of the flexible beam. Numerical simulations confirm the stability of the equilibrium configuration of the closed-loop system formed by the flexible beam together with the proposed controllers.

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A new type driven valve system for combustion engines has been presented, in which an actuator consists of a conical coil spring, a hollow motor and a screw. In the system, initial compressions and spring constant are controlled by an actuator. Hence, the resisting torque and the energy loss in a low-speed rotation are small in this system in comparison with normal engines. In addition, the jump and bounce phenomena in a high-speed rotation are suppressed by controlling initial compression and spring constant. The analysis for obtaining the jump and bounce phenomena of the present valve system has been presented. To validate the present valve system and the analysis, experimental tests have been carried out. It is ascertained that the load torque can be decreased, and initial compressions and spring constants can be controlled. The jump and bounce phenomena obtained by this analysis almost coincide with the experimental data.

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To improve efficiency of a coil winding machine, the speed of winding the wire is increased. Then the some problems occur with increasing the wire speed. For example, the wire is broken or stretched too much. This paper has a discussion a control of wire tension to avoid these situations. At first, we set a tension device at initial position. If the tension arm moves from the original position, we control an angle of arm to keep an original position by moving the drive motor. As a result, the angle of arm and the tension of wire are kept at specified value with small error. By the simulation, we confirm effectiveness of the proposed controller.

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Recent years, Modular construction method is used for shortening of a construction period in a large-scale construction site. Module is combination of construction and member of framework structured at factory. It is necessary for leveling of module when hauling module out of the ground with a crane in order to save the worker. It is able to solve this problem with calculating tension of wire beforehand. In this study, first time, we introduce method for calculating tension of wire that level off module and equalize each load of wire. Next, compare calculated value and experiment value. This is expected to shorten time of a construction period and simplify adjusting load of module.

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There are some approaches to control the vibration of a pendulum. Most of control models are composed of a pendulum and cart in a cart-type single pendulum system. However, our control method suggested in this report removes the pendulum from control model, and give the reference motions to state variables of the cart in order to control the vibration of pendulum. The reference motions are defined by Jacobian elliptic function which shows the solution of the free vibration of a pendulum. In this report, our control method is formulated and the effectiveness is verified by numerical simulation.

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Generally, we have a problem that the control inputs to stabilize pendulums and to swing up a pendulum interfere, when we swing up pendulums one by one in a multiple inverted pendulum system. To solve this problem, we proposed the subspace control for stabilizing the system and the method to swing up a pendulum by nonlinear resonance based on Jacobian elliptic function. In this report, we apply these methods to a parallel triple inverted pendulum system and verify the effectiveness of the methods by numerical simulation and experiments.

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CP control of a two-link planar flexible manipulator is studied. The technique to derive the target trajectory of the state variables and the computed torque wherein the tip position of the manipulator follows an arbitrary continuous path accurately is proposed. Also, the availability of this technique is confirmed by numerical simulation. The tip position follows desired trajectory accurately in both cases of the linear and circular desired trajectory.

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A system identification technique for a vibration isolation table by using subspace method (N4SID) and Frequency-Domain Least-Squares Approximation (FDLSA) is studied in this paper. The vibration isolation table is supported by four pneumatic actuators at corners of the table. A 3DOF mathematical model of the vibration isolation table is constructed. The regulator for the pneumatic actuator is driven by a stepping motor. A procedure to obtain the minimum-order-model is proposed, and the procedure can be fully automated. Effectiveness of proposed approach is examined by experiments.

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A new control device to suppress horizontal vibration in an elevator cabin, mainly caused by irregularity of a guide rail, is presented. The proposed control device consists of two rotary electric motors with eccentric masses. The one motor produces torque to rotate the eccentric mass according to the command signal from the controller, while the other motor rotates the mass to terminate the unwanted vertical force. The performance of the proposed system is examined through the numerical simulations considering the nonlinear characteristics of the rotating masses and the experiments with a miniature elevator cabin carrying the proposed actuator. The results indicate the proposed control device reduces the vibration without producing the unwanted vertical vibration.

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Recently, high-resolution measurement instruments such as probe microscopes have widely been used, since their price is getting down, their size is becoming compact. Therefore, these measurement instruments have been used at various environments. However, to use these instruments effectively, it is important to isolate the environmental vibration transmitted to these instruments. For this reason, we are developing new built-in type multi-axis vibration isolation device with inertia force generators (IFG). Designing this vibration isolation device, modal analysis and "direct inertia force control (DIFC)" was used. DIFC is the newly developed design method for the vibration control systems proposed by authors. Modal analysis and DIFC could make the complex control system design process more simple and clear. In this paper, we will show how the controller is designed, and also discuss the effectiveness of the method in experiment.

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This paper proposes a control method for the crank-slider mechanism as the active mass damper (AMD). Vibration isolation systems with spring support cause an increase in oscillating displacement at a natural frequency. A system of elastic supported machine frame with crank-slider mechanism can be expressed as time-varying system depends on crank angle. A state equation which contained variable parameters in coefficient matrices is derived from non-linear equations of motion. A controller is adapted the gain-scheduled control method for frame vibration reduction, and the linear velocity control method for crank motion control. State feedback gains are calculated by the linear quadratic regulator (LQR). The proposed method is confirmed by numerical analysis. As results, the system is reduced disturbance vibration by using the slider as active mass.

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Vibroacoustic modal filters for baffled structures in free space are formulated in terms of structural modal amplitudes, and then these filters are theoretically developed using PVDF films. PVDF film-based vibroacoustic modal filters perform the signal process to estimate vibroacoustic modal amplitudes themselves. Thus, any digital signal processor to calculate vibroacoustic modal amplitudes, which is required when point sensor-based vibroacoustic modal filters are employed, can be eliminated. The developed theory is verified through numerical simulations relating to a rectangular plate.

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This study presents dynamic behavior of a small size tire. A small size tire is used for personal mobility, for example, a bicycle, a wheelchair and so on. There are various steps and unevenness road in the actual traffic environment. The vibration is occurred when the small size tire passes a step or an evenness road. For the vehicle design, the force initiated by this vibration should be evaluated. In this study experiments are made using special device for behavior on bump for small size tire. Numerical model for small size tire is formulated by using mulitibody dynamics. In experiments, several types of step were used with various vehicle speeds. From measurements of tire, the acceleration acting on tire and the vertical displacement of tire, the effect of experimental condition were discussed. Furthermore numerical model is validated by experimental results.

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The present paper discusses the estimation of the road friction coefficient based on the brush model. This popular tire model is reanalyzed beginning from the conventional physical model, following which intrinsic expressions are derived. The grip margin that is defined as the residual tire force normalized by the radius of friction circle is estimated using the tire forces and self-aligning torque. A cubic equation is obtained as the grip margin equation for the isotropic model. The anisotropic model results in a quintic equation whose numerical solution is approximated by Chebyshev polynomials. The estimation method is verified by a numerical simulation using CarSim, a popular vehicle simulation software. The estimated friction coefficients are found to agree with the assumed values in the case of smaller grip margins, especially in lower friction conditions.

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In recent years, the car-body tilting mechanism using air springs is employed for shinkansen trains to speed up on curved sections.In this study, two analytical models, which can tilt the car-body based on the internal pressure of air springs, are developed. One model utilizes the change of air spring stiffness, and the other does the upward force resulting from the internal pressure of air springs.The numerical simulation shows the following results. The vehicle behavior of the two models are almost equal and they can reproduce the measurement data of actual vehicles on a curved section with vertical curve.

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It is difficult to reduce the transmitted noise through the internal panel of the railway vehicle by any existing active control methods, which are necessary to identify the vibration-modes of target structure, because the vibration characteristics of the interior panel changes while running. We propose a new noise control system that the noise insulation panel with piezoelectric material arrange, and enable the transmitted noise through a target plate to reduce by suppressing the vibration of the noise insulation panels with a simple analog control circuit. In this paper, after the equivalent mechanical models for a number of the piezoelectric material are shown, we demonstrate the analytical and experimental results about the control effects of the noise insulation panel and the transmitted noise through a target plate by the control system without identification to the vibration or transmitted noise characteristics of the target plate.

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The purpose of this paper is to reduce a impulse noise of floor structure by using the active noise isolation unit which constructed from the thin board and the piezoelectric vibrator. In the experiment, an additional weight is connected to the piezoelectric vibrator in order to improve the isolation loss of low frequency range, and examined its mass and number. The experimental results show that the isolation loss of low frequency range was increased as the additional weight became heavy, and the isolation characteristics were obtained by both control effects and those effects. Furthermore, depending on the selection of appropriate mass, the additional weight was also effective to reduce the floor impulse noise.

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It is light and development needs for a big insulation structure of the penetration loss are high. We are advancing the development of Active sound Insulation Units that arranges them with the Active sound Insulation Cell of the SISO control that enables the distributed control. Then, Active sound Insulation Units was newly developed with a Flat speaker in this research.

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This paper presents a new method to improve the transmission loss of a rectangular panel using active vibration control. This study can be applied to the window of a house or an office for making quiet space. Generally it turns out that the capability of sound transmission is determined by the mass of the structure. Therefore, in order to intercept the sound transmission at low frequencies, the material with heavy mass should be used. To obtain a high performance of interruptive sound using a light weight material, the active vibration control of the material can be used to improve the transmission loss.

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The purpose of this study is to apply Active noise control (ANC) to 3-dimensional space. Direct Adaptive Algorithm (DAA) proposed by Sano et al. is an effective algorithm because pre-identification of the secondary path, the path from a control source to an error microphone, property is unnecessary for this algorithm. However DAA has a problem that the control effect is affected by input noise level. Against this problem, we propose DAA with Step Size Auto Adjusting Method (DAA-SAM). This method normalizes signals into adaptive filters by reference signal. The normalized signals are used in updating adaptive filters. The validity of DAA-SAM against different input levels of impact noise and different secondary path properties is shown through computer simulations.

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On active noise control in 3-dimensional acoustic field, a control effect becomes worse when an evaluating point moves. Against this problem, authors proposed control by Filter-Map. This algorithm makes map by storing filters and updates the map. In this paper, the way to update the map is investigated. For appropriately updating, map reliability is calculated and the map is updated by using the map reliability. The validity of this method is confirmed by numerical simulation using acoustic characteristics in an anechoic chamber.

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In general, the sound waves propagate spherically in free space, which accordingly makes the global attenuation difficult. Placing number of microphones and control sources can improve the range of quiet zones and several studies have been done to this end, yet still limitations on implementation and cost cannot be neglected. In the present study, a new approach for active control of sound in free space is developed using high directional parametric loudspeaker as the control source. Both normal and the parametric loudspeakers are applied as control sources and results are compared based on measurement of interfered sound field. It is known that the suggested ANC system can mitigate sound locally but cause less influence on sound field in circumferential space.

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The present research studied about the noise reduction method based on the wave absorbing principle of the rolling noise which spreads over a seeable open space from the rail by the devices installed on the proof cover of railway vehicle. A device unit consists of one controller, one parabola-microphone and two plane-wave speakers. First, based on the acoustic numerical simulation analysis by using the 3-D Boundary Element Method, the methods of improving the previously proposed device construction concept were examined and then three kinds of new type devices were manufactured. And the fundamental characteristics of respective device were grasped experimentally. Then decentralized control experiments by using multi- device units which were estimated to be the best by the simulation and the above experiments were carried out and the method of improving the control effects of total system consisting of multi-device units was examined.

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In recent years, the drive-system noise and vibration generating from the motor vehicle of the narrow gauge line vehicles are decreasing by adoption of the low noise traction motor, low noise coupling and a low gear ratio. However, the noise of the drive unit is expected to be further lower at present. In this paper, we explained the present situation of the drive-system noise and vibration of the narrow gauge line vehicles, and aiming at finding out effective countermeasures, we carried out several analyses. We introduced these analysis cases that included a sound source separation method of the drive system noise, the fluid acoustic analysis of the traction motor, and the analysis of a structure-sound field of the gear device.

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Finite element method and boundary element method were applied to develop the low-stress and low-noise lightweight wheel. A design methodology was developed and applied, leading to the development of new plate shapes of wheel whose stresses generated were lower than those of conventional corrugated wheels. Candidate plate shapes were selected based on the analyses. Next, transient dynamic analyses were carried out for the wheels. At the same time, to verify the analytical results, these wheels were manufactured and experiments were implemented. Finally, sound analyses were performed and results were compared with that obtained by field measurements. From this study, a new plate shape of lightweight railway wheel was obtained that reduces the radiated noise as well as the maximum stresses generated in the plate region.

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This paper presents the theoretical procedure to predict the vibratory response and radiated noise of the engine block coupled with the rotating crankshaft and gear train shafts which drives the fuel injection pump and valve system. The exciting forces acting on the engine block and shaft system are combustion pressure, inertia forces of the moving parts, piston slap forces, fuel injection pressure and valve driving force and torque. This method is applied to estimate the effect of the backlash of the gear train on the gear impact forces, engine block vibration and radiated noise. The calculated results are compared with measured ones and the availability of this analytical method is discussed.

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This report deals with vibro-acoustic analysis using three-dimensional FEM for automotive seat structures having porous materials and metal frames. There are two media (i.e. internal air and a resin block) in the porous materials for the seat. By carrying out numerical analysis related to the model test, the porous materials for the automotive seat have sound absorption effects for cavity resonance in a room. This effect is mainly due to viscosity of internal air in the porous materials. Further the porous materials also have damping effects for the structural resonance of the metal seat frame under impact excitation at the metal frame. This effect is mainly due to viscoelasticity of the resin block in the porous materials. Furthermore, under an acoustic excitation from a speaker, vibration amplitudes of the metal frame increase by attaching the porous materials to the metal frame. It is "an effect of a sail" of the resin block in the porous material, which increases vibration level of the seat metal frame by receiving sound pressure. This effect can be simulated using Biot model for the porous materials, which have coupling effects between elastic deformations of the resin block and acoustic waves in the internal air.

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This paper describes musical scale generating mechanism of a steel drum which is made of a bottom of oil drum with many protuberances. Since the shapes of protuberances must be designed to generate natural frequencies which agrees with those of music scales, the steel drum generates musical scales when one hits the protuberances with a wooden stick.. In order to clarify the musical scale generating mechanism, FEM modal analysis of the steel drum is carried out based on a FE model obtained with shape measurement with a 3D-CMM. There exist modes of vibration in which the only a protuberance part vibrates at the natural frequency as same as the musical scale. Through the forced vibration analysis with impulse response and sound radiation analysis, sound pressure radiating from the steel drum can be reproduced.

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Sound is often generated by the vibration of a plate structure. In order to consider the counter measure of noise, it is useful to carry out a numerical simulation of the vibration of the plate. The plate often has a strucutre of non-uniform thickness. An elevated road or railway track is a typical example of such a structure. The extension of Mindlin plate theory has been considered and the implicit time marching method has been adopted, here. The comparison between the results obtained by 3-dimensional theory and Mindlin plate theory was made. The good agreement between two methods was obtained.

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Railway viaduct is one of the structures, which is subjective to reduce the noise since it causes an excessive degree of noise attributable to vibrations of the structural members such as floor slab, and it is desirable to predict the structure-borne noises. However, conventional methods such as Finite Element Method (FEM) are difficult to apply to predict structure-borne noises. Therefore, we have developed a new method by extending the vibration of flexure of members to the entire structure. As characteristics of the method, the structure is divided into some subsystems to analyze readily the vibration of each system, and define the trial functions for each system. As the result of comparison of the calculation and measurement of noise adjacent to the floor slab of concrete viaduct constructed on Shinkansen line, it revealed that the proposed method is able to predict approximately the structure-borne noises.

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The previous study derived the modal expansion of structural intensity for flexural vibration on a beam. Structural intensity is expressed by the superposition of modal terms composed of weight coefficients and cross-modal functions. As increasing the weight coefficient, the cross-modal function can be strongly or weakly exciting. The cross-modal functions are determined by the natural modes and the weight coefficients are determined by the natural frequencies, natural modes and the excitation point. Thus, the weight coefficients can be increased or decreased by the changing excitation condition. In this paper, firstly the modal expansion of structural intensity for flexural vibration on flat plates is newly derived. Next, based on the modal expansion, we propose a method to determine the excitation condition for the realization of structure intensity distribution desired. The application results on the flat panel and the compound plate structure indicate the validity of the method.

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A trial study to examine if the sound reduction effects in the rocket fairing are obtained or not was carried out by using, so to speak, Sound Decreasing Structure, considering that concerned Structure is very similar to the structure of existing rocket faring. Specimens are honeycomb sandwich plate structures composed of outer thin Al skin and inner porous Al of sound absorbing material in stead of Al skin. They were excited acoustically by white random noise in the rectangular acoustic tube and the transmitted SPL was measured in the anechoic chamber and compared with the excitation SPL. As a result, it turned out that sound decreasing effects were actually observed if the SPL is normalized by the velocity SPL of specimens. And besides if the sound absorbing effects of reflection sounds from the inner walls of faring model are added in addition to the above decreasing ones by setting the concerned models on all surrounding walls in the chamber, it was observed that SPL reduction effects were remarkably large in the low frequency range that is important from the practical point-of- view of breakage of satellite components.

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This paper describes a noise reduction design of transient sound radiating from a thin plate structure excited by random impact forces. The overall sound power of a coin storage box of a coin counting machine is set as an objective function to be decreased. The location and size of dimples adding on the box are set as design variables and are optimized with the sequential quadratic programming method. The sound power radiating from a box with optimum dimples reduces by 3.0dB. It is then confirmed that the proposed method is effective and useful for reduction of random transient sound.

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This paper proposes to reduce a heavy-weight impact noise of double floor. The magnetic levitated leg using the repulsion of permanent magnet has been developed to isolate the impact force from the double floor. In the experiments, construction method of the magnetic levitated legs is investigated from the displacement of static or impact load, and the floor impact noise. The experimental results show that the heavy-weight impact noise could be reduced about 10dB in range of 32-250Hz octave band. However, the displacement of static load was increased than the traditional rubber support legs.

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This paper proposed a new method which can reduce the noise in the duct by use of the perforated panel. First, in order to analyze the acoustic field in the duct with the perforated panel, the theory of the acoustic property of the perforated panel was established and the validity of the theory was checked by calculation and experiment. Second, in order to calculate the acoustic field in the duct by boundary element method (BEM) more exactly than the conventionally method, new analysis methods on BEM were proposed which can calculate the acoustic filed including the effect of the sound attenuation on the rigid wall and can calculate the acoustic field separated by the perforated panel. Finally, noise reduction performance of the perforated panel was measured by use of an experimental apparatus imitated a fan duct and was calculated by BEM, and results of the experiment and calculation showed the effectiveness of attaching the perforated panel to the duct.

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Using a dynamical systems approach and numerically computing the stable manifold of an equilibrium in the corresponding Hamiltonian systems, we propose a numerical technique for obtaining derivatives of stabilizing solutions to Hamilton-Jacobi equations for nonlinear control systems. We give an example for an inverted pendulum and demonstrate the proposed technique in both numerical simulations and experiments.

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Self-excitation thechnique is known as an effective excitation method for a cantilever probe of the atomic force microscope to measure the surface of a biological sample in a liquid environment. In this research, we deal with a van der Pol type cantilever probe, which is previously proposed to realize the non-contact mode, and experimentally examine the relationships between the response frequency and amplitude and the gap of the cantilever probe and the surface of sample. We examine the natural frequency of the cantilever in liquid. From the result, it is confirmed that the cantilever oscillates with a low amplitude that can detect the surface of the sample without giving damage. While it is difficult to estimate natural frequency of the cantilever under external excitation in liquid, it is easy to estimate it under van der Pol type self-excited oscillation.

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We study trajectory generation and attitude control of a two-dimensional space robot floating in space. The conservation law of angular momentum leads to nonholonomic constraints and hence results in inducing the so-called geometric phase of the base motion, while from the view point of attitude control of space robots, we need to control the attitude of space robots with no phase. To do so, we develop equations of motion of a two-dimensional space robot in the context of regular Lagrangian systems with holonomic kinematic constraints and we propose a trajectory planning of a space robot with controlling the base attitude.

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In order to stabilize the inherent unstable system like the inverted pendulum on a cart, severe judgment of situation is required. Accordingly, it can be expected that the human operators exhibit a complex behavior occasionally. This paper tries to identify the individual difference of human operator's behavior from time series data by using fuzzy inference and acquire individual skill of human operator. It also investigated the chaotic behavior of human operator and the possibility of the formation of complex system in the learning process of the human operator with difficult control objects. The operators in the experiment are skilled to some extent in stabilizing the inverted pendulum by training, and the data of ten trials per person were successively taken for an analysis, where the waveforms of pendulum angle and cart displacement were recorded. The maximum Lyapunov exponents were estimated from experimental time series data against embedding dimensions. It was found that the rules identified for a fuzzy controller from time series data of each operator showed well the human-generated decision-making characteristics with the chaos and the large amount of disorder. and the individual difference of chaotic and complex human operation can be identified with fuzzy inference.

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In this paper, we show how a Dirac structure on the cotangent bundle can be induced from a given constraint distribution and also show how implicit port-controlled Lagrangian systems can be developed by using the induced Dirac structure, which may be regarded as an interconnection of mechanical networks by analogy with electric networks. It is demonstrated that the implicit port Lagrangian system can be applied to a class of nonholonomic mechanical systems by an example of a vertical rolling coin.

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A new design method is proposed here to maximize the fundamental frequency of laminated composite plates reinforced by optimally shaped curvilinear fibers. Spline functions represent arbitrarily shaped fibers and the Ritz solution generates frequency equations. The optimum curvilinear shapes are searched for the maximum fundamental frequencies using genetic algorithms, and the increments of data points which define the spline shape are used as design variables under limitation of undulation. Comparison of the present analysis method with finite element method gave good agreement in terms of eigen frequencies and vibration modes, and the optimization results showed that the present plate with optimally shaped curvilinear fibers gives higher or equal fundamental frequencies when it is compared with the conventional plate with parallel fibers.

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This study proposes an optimization method to deal with free vibration of shallow shells with generally curved surfaces expressed in terms of cubic polynomial functions. Such shell structures with variable curvature are recently found in automobile and other design-oriented structural applications. In the first example, the fundamental frequency is maximized as the object function with respect to the curvature. The second example is given to maximize the difference of the lowest two frequencies, and the third one is to find the best curvature design to fit to any desired vibration frequency within the physically possible range. The optimization technique employed here is a part of functions in ADS program that is based on mathematical programming.

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The design sensitivity is very important information for designing and manufacturing composite material structures. In the present report, a certain type of sensitivity problem is studied for free vibration of symmetrically laminated rectangular plates simply supported along the edges. An analytical solution for sensitivity of natural frequencies is presented. Then the present solution is applied to some numerical examples of the plates, and the accuracy and effectiveness are verified.

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This paper presents the free vibration analysis of fiber reinforced plastic composite plates by using Discrete- Layer Theory. For this purpose, the governing equations are formulated for a cross-ply laminated, simply-supported rectangular plate based Higher-order Shear Deformation Theory (HSDT), Multi-Layer Theory (MLT) and Discrete-Layer Theory (DLT), respectively. In the numerical examples, natural frequencies and specific damping capacities of the plates with different stacking sequences and dimensions are calculated numerically by assuming complex elastic modulus. Finally the applicability of each analytical model for damping analysis is studied by comparing with numerical results obtained respectively.

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This paper presents free vibration analysis of composite plates with visco-elastic material. For this purpose, maximum strain and kinetic energies of the plate are derived analytically based on the Classical Lamination Theory, and then the frequency equation are obtained by using Ritz's procedure. In numerical examples, the identified models of the material characteristics for actual visco-elastic materials by using spring-dashpot models or fractional derivative models are employed and natural frequencies and specific damping capacities are obtained numerically. Finally an experimental study is also carried out by using the experimental modal analysis, and the accuracy of identified models is discussed form the comparisons of numerical and experimental results.

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In "Recommended Practice for LNG Aboveground Storage" and "Recommended Practice fo LNG Inground Storage", the allowable compressive stress of knuckle plate is linked to the allowable tensile stress. According to the change of the safety factor of allowable tensile stress in ASME Boiler and Pressure Vessel Code, the safety factor in these Practice has been restudied. In connection with the restudying, the integrity of the knuckle plate is investigated.

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