This research concerns high efficiency propulsion method of multi-articulated robot by decentralized control using local feedback control. Recently, various robots, which are useful when disasters happened, have been studied. The high efficiency driving of these robots is required, because there are limits to an energy for robot propulsion at a time of disaster. To meet this requirement, the driving method using resonance point was proposed. On the other hand, natural frequencies of propulsion robot are varying in synchronization with the change of external environment. In this paper, the new driving method of propulsion robot using nonlinear control, which drives at the resonance point automatically, is proposed. Especially, investigation of the proposed method for large degree of freedom robot is done. Firstly, optimal excitation force of vibration propulsion mechanism is shown. The excitation force signal, which is realized the highest efficiency driving, is clarified by the driving experiment using various excitation force by centralized control. Secondly, the design method of new controller for decentralized control is introduced. The excitation force waveform of conventional control is square wave because of saturation element to limit the amplitude of excitation force. The new controller has the nonlinear damping element in place of saturation element. Finally, it is confirmed that the decentralized control using new controller can realizes the highest efficiency driving. The driving efficiency of the propulsion mechanism improved because of the optimization of the excitation force waveform.

In this study, we proposed a method for obtaining high contributing whole body vibration behavior to the interior noise by integrating separated measurement vibration data set. As the candidates, two integration methods (1: Averaged response point signal, 2: High contributing principal component) were prepared and these methods were applied to a simple plate for the accuracy verification by comparing the behavior with the original OTPA PC model. As the result, High contributing principal component method was found to have an ability for obtaining correct high contributing whole vibration behavior with small scale measurement system.

We have developed one-pitch phase analysis method (OPPA method) that measures the three-dimensional shape of a planar object at high speed. Using this, we constructed a system for measuring changes in 3D shape at high speed, and developed an OPPA vibration distribution meter for measuring vibrations of 3D objects. This system allows frequency analysis for each pixel of the camera. Each pixel of the camera is perfectly synchronized sensors without contact to an object. And it is quite easy to use. An accurate vibration distribution measuring device can be constructed. As an application example, the vibration of the body of a car, engine head, etc. is measured. The vibration mode analysis is also performed. The measurement principle and application examples are shown.

This paper proposes a methodology to adjust an excitation force amplitude generated by laser-induced plasma shock wave. To realize a remote sensing technique, we investigate a non-contact method to vibrate target mechanical structures or infrastructures to be inspected using laser ablation or laser-induced plasma shock wave. Laser ablation damages an excitation point of the structures because the laser beam is irradiated to the point. Laser-induced plasma shock wave is completely non-destructive method, but the amplitude of the excitation force of laser-induced plasma shock wave is less than that of laser ablation. Furthermore, laser-induced plasma shock wave is spherical, and only a portion of the wave is used to vibrate the target structures. In our experiment, an acoustic lens is used to focus laser-induced plasma shock wave, allowing a control the amplitude of the excitation force of that.

The finite element method is widely used to predict mechanical vibration for the purpose of improving the performance of mechanical products. However, in complex structures such as automobiles, much effort is required to make the accurately entire system model. Therefore, in this research, we propose a method to identify the state transition matrix of the entire system by hybridizing the state transition matrix obtained by finite element modeling only the target component and the state transition matrix identified from the experimental data. In this paper, as a numerical verification, we apply the proposed method to a beam model whether it is possible to predict the vibration and the vibration change due to structural modification. 岐阜大学大学院 Graduate School of Gifu University

Computer simulations using the combination of finite element method (FEM) and modal analysis are now useful methods for vibration prediction. However, when it comes to detailed models of large-scale structures, it takes time to evaluate and reduce each characteristic mode one by one. Especially, coupled modes that consist of global and local deformations require careful treatment for reducing vibrations. In order to reduce vibrations of coupled modes, it is essential to reinforce respective parts that relate to each deformation with proper balance. This is because applying incorrect reinforcement contributes to vibration increase. The purpose of this study is to classify each characteristic mode into groups based on its dynamic behavior and approaches for vibration reduction. It is effective for panel structures to focus on global and local deformations of each mode. Based on deformation shapes and their correlations, the characteristic modes of a panel structure are divided into three groups: global modes, local modes and coupled modes. By means of the classification, effective vibration reduction approaches for each mode group is presented. The behavior of coupled modes’ vibration increases and decreases caused by different reinforcements is also demonstrated. Furthermore,

The car is assembled from a large number of supplier’s parts which are installed onto the OEM-designed body to form certain function. Therefore, it is inevitable that noise and vibration problems in the car will occur when the parts are installed. Thus, if the resonance frequency of a main system (OEM's car body) is predicted through characteristic of subsystem (supplier’s parts), this will save a considerable amount of effort and time during the initial design phase. In this paper, a method of predicting multiple resonance frequencies of a whole structure due to mounting of small parts is presented based on the monotonicity theorem proposed by Weyl, and numerical examples are used to verify this theory.

As represented by electric vehicles, there is an increasing demand for efficient electric motors in various industrial areas. For the development of such electric motors, consideration of electromagnetic noise and vibration produced by the motors is inevitable. The electric motors consist of stationary and rotating components, which are respectively called as stator and rotor. When the electric motor is in operation, electromagnetic force is generated between the rotor and the stator. The electromagnetic force is used for the generation of torque, but as a byproduct, the stator is subjected to oscillatory load, which produces structural vibration of the stator. In this paper, we focus on the vibration analysis of induction machines, including vibration analysis under operating conditions, and experimental modal analysis. Spectral analysis of the vibration response of the induction machine revealed that large components can be observed at frequencies that are related to mechanical resonance, and side-bands of the integer multiples of the carrier-frequency of the PWM control.

The pantograph/catenary hybrid simulation (HS) system evaluates the performance of pantographs considering dynamic interaction between pantograph and catenary. In order to calculate dynamic motion of the catenary, the conventional HS uses contact force between pantograph head and catenary that is measured by a loadcell. However, if the contact point changes with time, it is difficult to measure the contact force using loadcell. This paper proposes an HS method that uses contact force identified based on the strain and acceleration that are measured on the pantograph head. The calibration factors to calculate the contact force are determined by static loading test and excitation test of the pantograph. The proposed HS method is compared with the conventional HS that uses the loadcell to measure the contact force. If center of the pantograph head is excited, the obtained contact force and pantograph head displacement of the proposed HS testing correspond with those of the conventional HS testing. However, if the excitation point is far from the center of the pantograph head, fluctuation of the contact force and pantograph head displacement of the proposed HS testing is smaller than those of the conventional HS testing. The difference between proposed and conventional HS testing may be caused by the missing transfer path of the load from contact strip to the pantograph head.

In machine tools, the low frequency vibrations are produced due to the acceleration and deceleration of the machining table. They lead to the relative displacement between the tool and the workpiece, resulting in lower machining accuracy. The vibrations are mainly rigid body vibrations of the entire machine installed on the foundation. Although they are affected by the characteristics of the foundation, it is difficult to theoretically estimate the vibration characteristics of the foundation. In this study, we propose a method for predicting the vibration characteristics of the machine installed on the foundation before its installation based on the FRF(frequency response functions)-based substructuring method. The method combines the FRFs of the foundation measured by the vibration test with those of the machine. As a basic study, we verify the validity of the prediction method using an analytical model for a rigid body with a flexible appendage supported by elastic bodies with which the supports and the foundation are modeled. Furthermore, we examine the support location to reduce the relative displacement between the rigid body and the flexible appendage.

In this study, we investigated the factor of large door vibration from the relationship between the compressor input force and the vibration mode of the refrigerator body by using transfer path analysis (TPA) to decrease the door vibration. At first, we measured the door vibration of a home refrigerator at various compressor rotational speeds to determine the rotation speed at which the door vibrates largely. Subsequently, the main contributor of the vibration was clarified using TPA. As the result, the door vibration was found to be increased by the door vibration mode and the input force along updown direction from the compressor. Accordingly, structural modification was carried out to decrease the door vibration considering the high contributing part. Finally, the vibration amplitude could be decreased about 90% at maximum.

In the design of the mechanical structure, the improvement of noise and vibration (NV) is important. The transfer path analysis (TPA) is the method which is widely used for the purpose of solving NV problems. It provides the way to analyze the system under the excitation. In this paper, applying the TPA based on the GTDT method to a simple finite element method (FEM) model, we try making the improvement of vibration characteristics of the model and consider the characteristics and the drawbacks of the GTDT method.

The experimental modal analysis is a technique for identifying modal parameters from vibration tests of mechanical structures. The single-degree-of-freedom (SDOF) methods using the frequency response function (FRF) is widely used in the actual application for identifying the modal parameters because of its simple operation. It is noted that the conventional SDOF method can be only applied when the target mode is dominant. But in some cases, the effect of the non-target mode can’t be ignored. In such cases, the multi-degree-of-freedom methods are used, while it is more effective if the modal parameters can be easily identified by the SDOF method. In this study, we propose a new SDOF method for identifying the modal parameters even though the vibration modes are relatively close. First, the theory of identification by the linear fit method in the case of approximating non-target mode components as a polynomial is explained. Next, the behavior of mode components close to the target mode is shown using the FRF of the cylindrical shell. Finally, we compare the modal characteristics identified using the conventional method and the proposal method, and conclude that the identification accuracy can be improved by the proposal method.

Modal properties such as natural frequencies, modal shapes and damping ratio are essential to understand structural dynamics of mechanical systems. Therefore, operational modal analysis (OMA), extraction of the modal properties without input signals, has been proposed to easily extract the modal properties under operational conditions. Recently, OMA for underdetermined systems, i.e. number of measurements is less than that of active modes, has been paid attention to reduce the number of sensors. This paper proposes the OMA framework for the underdetermined systems based on Bayesian tensor decomposition of second-order statistics data. The proposed method enables us to extract the modal properties from underdetermined systems without tuning the number of active modes because rank of the tensor data corresponding to the number of the active modes is automatically determined via Bayesian inference. To show advantage of the method, the modal properties are extracted from artificial vibration data obtained from a mass-spring system under the operational and the underdetermined conditions.

It is essential to investigate the vibration characteristics of the railway vehicle carbodies in order to improve the ride comfort of passengers. In the previous studies, the focus has been on the natural modes of the carbodies whose natural frequencies are up to 15-20Hz, because the passengers are sensitive to the vibration around such a frequency range. On the other hand, it is getting noticed that the vibration reduction for high-frequency is also important, especially for high-speed railways. The authors therefore have been tackling to estimate the vibration modes consisting of the natural frequencies up to 30-40Hz. In this study, the tested vehicle is excited by a shaker and the vibration accelerations in 3 directions are measured on the ceiling and the Žoor of the carbody with the much and denser sensors than heretofore. The two kinds of experimental modal analysis methods are then applied to estimate the modal parameters such as the natural frequencies,modal damping ratios, and vibration shapes.

When the dynamic design of a structure is carried out by using Finite Element Method, the dynamic characteristics of the member of the structure have to be identified in advance. Especially, the damping property of the actual complex shaped member is sometimes assumed to be same as the one of a simple shaped member with the same material. The damping properties are often become a function of the frequency or the order of vibration mode, so it is not certain whether we can apply the dynamic characteristics of the simple shaped member to the complex shaped one or not. In this study, a beam specimen made of steel is adopted, and the modal properties of both uniform shaped specimen and L-shaped one are identified, then influence of the shape processing is investigated on the damping property. As a result, it is recognized that the damping property is high in the low frequency band and low constant in the high frequency band. And the damping property of the L-shaped specimen is higher in the low frequency band than the case of uniform specimen, while it is almost same in the higher frequency band. Moreover, the effect of processing position on the modal properties is investigated. As a result, it is recognized that when the processing position is close to the edge, the increase of damping property is noticeable in low frequency.

Recent lunar explorations have revealed that water ice exists at the polar regions of the Moon. Because the exact location of ice, the depth from the lunar surface, its chemical and physical forms, and the amount of water are not clear, not only government space agencies but also private companies worldwide are planning to search ice directly by oper ating uncrewed rovers on the Moon. Japan Aerospace Exploration Agency is planning to operate a long drill, approxi mately 1.5-m long, which will be screwed in the regolith layer of the lunar surface, and regolith mixed with ice will be captured and lifted from the inferior deep portion of the regolith layer to chemical and physical analyzers mounted on the rover. A long-range vertical transport technology of regolith and ice particles is indispensable to realize the explora tion of ice under the lunar ground. To this end a vertical sampling and transport system for lunar regolith and crushed ice particles has been developed utilizing a vertical vibration transport mechanism that is possible to lift particles to a high position, easy to control, and has a simple structure. In this mechanism, the friction force generated between the inner wall of the tube and particles is mainly conveyed upward and particles are collected by oscillating up and down the tube inserted vertically into the bulk of regolith. A parametric experiment has been conducted to deduce an efficient transport system, and it was demonstrated that crushed ice particles mixed with lunar regolith simulant, as well as rego lith particles, are lifted for long distance by optimizing the configuration of the system and its operational scheme.

Although a snake-like robot can move in fluid as well as on the ground, it has to drive many actuators, so it is necessary to reduce the power consumption and improve the moving efficiency. Also, for a pipe survey, a snake-like robot must move in the environment such as not only water but also mud and clay by undulating motion. The survey of optimal behaviors in water and mud by using the numerical model is effective to resolve these problems because many combinations of the surrounding environment and parameters of input torque can be tried on the computer. For this purpose, we aimed to construct the numerical model of a snake-like robot that swims in water and oil with different kinematic viscosities. First, we performed experiments of the snake-like robot with 8 links swimming in three kinds of fluids, water and two kinds of oil with different kinematic viscosities, and measured the joint positions of the snake-like robot during the swimming motion. Next, two numerical models of the snake-like robot swimming in water and oil were constructed, whose unknown coefficients were identified by using the unscented Kalman filter (UKF) with the measured joint positions. As a result, we succeeded in constructing models in which the calculated position of the center of gravity (COG) of the snake-like robot agreed with the experimental values when the same input torque was applied to the numerical model as in the experiment.

We propose a front wheel mechanism that makes it easy to climb steps in order to reduce the burden on wheelchair users. Characteristically, by keeping the distance from the axle to the contact point between the wheel and the step to a minimum, the rotational force that prevents the step overcoming the step due to the load on the shaft is reduced, and the required force can be reduced. A mechanism is used to adjust the distance, which is called axis movement. Also, by realizing the wheel mechanism as a caster, it is possible to maintain the same moving performance as existing wheelchairs. We show the usefulness of the proposed wheel mechanism by attaching the wheels to an existing wheelchair and conducting a motion test.

In nature, a wide variety of creature uses flapping wings to fly. Recently, a flapping flight system imitating a flapping wing has been reported in the field of robotics. Despite recent advances, flapping wings have only in been studied in a small fraction of these biosystems. Consider the myriad of creatures, many challenges remain in understanding and studying flapping wings. Based on this consideration, our study direction is to study the flapping wings of ladybugs and then to realize a ladybug-based artificial flapping wing. Based on this consideration our study direction is to study the flapping wings of ladybird and then to realize a ladybug-based flapping mechanism. To that end, we are developing a prototype of a simple flapping mechanism that can make flapping based on the flight movement of a ladybug. Currently in the process of determining the prototype concept and developing it. In this presentation, we will introduce survey results obtained through simulations and experiments using prototypes.

The ASEAN countries, particularly Indonesia, are important partners in terms of political and economic stability in the region. Indonesia is the largest country in ASEAN, and has kept good relation with Japan as mutually beneficial partners. As compared to other ASEAN countries, such as Singapore and Thailand, the average age of Indonesian is significantly younger around thirty, and because of this, sustainable development is expected in the future. For such development, there is no doubt that higher education in engineering should play very important role. From my experience as JICA Academic Advisor for two years and seven months, situations surrounding higher education and other aspects are summarized here for your information. It is also assessed on how Indonesian government copes with globalization

Kansai University conducts an "Early Special Research" elective subject for the fall semester for third year mechanical engineering students who have earned credits. It is common to carry out graduation research in advance under the name "early", but in this laboratory, Design and manufacturing themes are offered to the students who are interested in design and manufacturing by himself. The students learn the kinetic principle of phenomena, design, manufacture model devices, and operate the devices to measure their performance. In this paper, five research themes, i.e. 2 DOF forced vibration, unbalanced vibration of rotating machine, one DOF vibration on running belt, inverted pendulum, and bending and torsion flutter of wing are discussed.

This paper introduces mechanics education using visual materials, experience materials, and confirmation quizzes. At the "beginning" of the lecture, students are guided from a physical or concrete existence to abstract concept. In engineering mechanics, we have created teaching materials to experience mass 1kg, force-deformation relationship, forcemotion relationship, support reaction force, stability of equilibrium, the center of gravity, and moment of inertia. Moreover, we have created teaching materials to experience free vibration and natural frequency of a one-degree-of-freedom vibration system, forced vibration and resonance, and whirling of a rotating shaft in mechanical mechanics, and PID control of positioning in control engineering. Using these teaching materials, demonstration experiments are conducted by teachers, and experience experiments by students themselves. At the “end” of the lecture, the points of the lesson are summarized in simple illustrations and short sentences to create a “mental model” that can be remembered for a long time. Moreover, in order to strengthen and establish the mental model that we created, we introduce confirmation quizzes that select the correct one from among sentences and diagrams that contain mistakes.

A spring-operating mechanism for high-voltage gas-circuit breaker has been developing. The simulation by using 1D-CAE method is carried out for this mechanism. The pneumatics, rigid body, spring, hydraulics and solenoid are modeled with each functional icon placed in the united simulation system. We confirmed good accuracy in plus or minus 5 percent for the simulation and the experiment on the prototype design. This simulation can also be applied for three pole gang-operated mechanism. Each motion of the pole is not in sync because the torsion of main shaft appear strongly. The parametric study for the designs has performed. Finally, the design of mechanism with the auxiliary damper was obtained.

Vehicle drivability is an important factor that is directly linked to comfort and product value. In the development of drivability performance improvement, there are cases that screening evaluation is performed by actual vehicles or simulation with CAE for the target phenomenon. However, the worst condition of the drivability phenomenon depends on the hardware and control specifications of each vehicle and it is difficult to extract by vehicle test. It is necessary to comprehensively test with a simulation or actual vehicles, and it is difficult to consider it in a limited resource. On the other hand, the objective function can be optimized with the minimum number of experiments by using Active Learning. In this study, we propose Bayesian Optimization that can predict the worst condition with minimum CAE calculation as a prediction method. Furthermore, we propose a development process using Bayesian Optimization. By using this method, a reduction in the number of calculations can be expected. Therefore, it can be used as a search method for the worst condition of drivability phenomenon at pre-screening in the initial stage of vehicle adaptation.

This paper addresses a class of self-excited vibration phenomenon’s modeling and simulation problem．A typical self-excited vibration occurs in hydraulic machine due to the sliding friction at the discontinuous contact/collision．Modelica models including mechanical and contact element using the 2-dimension polygon are applied to study the self excited phenomenon．The modeling and simulation analysis results illustrate the effectiveness of the model．

Modelica, which is a de facto standard tool that embodies the concept of 1D-CAE, is a programming language that has the potential of not being caught in the mere conventional mechanical engineering domain, the suitability for crossfield cooperation with forefront technologies, such as IoT and MBSE (Model Based Systems Engineering). There are two types of 1D-CAE approaches, "concept based 1D-CAE" and "model based 1D-CAE" which lead company's success. The paper attempts to explain the structure of 1D simulation using the five-level method of 1D modeling.

This study tries to evaluate the elastoplastic dynamic behavior of mechanical components during earthquake in resonance with their supporting structures, focusing on the response reduction due to inelastic energy absorption and the increase of earthquake load cycles. Four simple two-masses-models with two shear springs, those are linear loaddeflection characteristic for the structure and bi-linear type one for the equipment, are excited with 52 strong earthquake motions observed in Japan, and their response spectra are resulted parametrically with relatively small ductility factors ranged from 1.25 to 5.0. As results, it could be concluded that the seismic design demand reduction estimated by the constant-energy-rule can be reasonably achieved for both of resonant and soft frequency region of the equipment, and the numbers of energy-equivalent earthquake load cycles increases in accordance with targeted ductility factor increase, especially in the resonance between equipment and its supporting structure.

The effect of the peak frequency was considered by using the calculation method of the cumulative fatigue damage during the earthquake of the piping system developed in the previous report. For verification, we simulated the cantilever pipe with concentrated mass at the tip when the actual earthquake motion was fast-forwarded and investigated the effect of the change of peak frequency on the cumulative fatigue damage. The approximation method is based on the ASME O/M code for general piping, and the results may be applicable to general piping systems. In the case of the same piping system configuration, the effects of higher modes were also considered.

In order to incorporate the nonlinear effects of restoring force into the seismic design and evaluation of equipment and piping systems, it is very useful for practical use to easily estimate the elasto-plastic response to earthquakes. Previous studies have shown that the property of energy conservation is applicable in short-period structures and the property of displacement conservation is generally appropriate in long-period structures. However, it is not clear how applicable these rules of thumb are to the equipment and piping systems installed in nuclear power plants. This paper presents the applicability of the conservation rules to equipment and piping systems in a nuclear building. Seismic response analyses of pre-stressed concrete containment vessel building of nuclear power plant is carried out with BCJ-L1 and BCJ-L2 provided by the building center of Japan. Then, the time histories of the floor responses are used for calculating the elastoplastic response. As a result of this study, it was found that the property of energy conservation tends to hold when the ductility factor is small in shorter period range at the boundary of the predominant frequency of the floor in the building, but a large deviation occurs due to the elongation of the period which comes from increasing the seismic response due to resonance. And, it was also found that tend to have the property of displacement conservation, in a long-period structure although large errors are observed.

In order to confirm that an equipment has an appropriate margin for the ductile failure at full-section yielding by limiting the load acting on the equipment to the limits of the primary stress intensities for level Ds service limits, a load at which the stress was equal to or less than the limits of the primary stress intensities was obtained and compared with the collapse load by the limit analysis. A cantilever, a 4-leg support tank, and a core shroud were chosen for this comparison. As a result, the load at which the stress was equal to the limits of primary stress intensities was lower than the collapse load by the limit analysis in all the equipment. In addition, the cantilever applied the limit of class 1 vessels and the core shroud applied the limit of core support structures had small differences in load, and the 4-leg support tank applied the conservative limits of support structures resulted in a large difference in load. From these results, it was reconfirmed that the limits of the primary stress intensities for level Ds service limits are limits that have an adequate margin for the ultimate strength of equipment.

Many companies have carried out vibration test because it is one of the most important programs in the manufacturing industries. Test conditions and the acquired transfer function have been accumulated. The purpose of this study is establishment of the assessment method of the failure probability for the similar structures by statistically processing these data. In this report, we assessed the failure probability of the cabinet which is a simple structure. We analyzed the test results of fifteen cabinets. At first, we classified these cabinets into some categories as to the input wave, the fixed position and the mass. We calculated the representative transfer function, which is middle between the maximum transfer function and the minimum transfer function. Furthermore, we calculated transfer function uncertainty with the representative transfer function. We created the failure probability curve with this uncertainty. However, this uncertainty is different in the frequency. Accordingly, we created the failure probability curve of each frequency based on each frequency uncertainty. Furthermore, we created the 3D failure probability curved surface. We could assess the small cabinet with the 3D failure probability curved surface. The failure possibility of the cabinet can be estimated based on the failure probability curve before vibration tests. Finally, we could assess failure probability of cabinets considering that uncertainty is affected by vibration frequency.

It is important for overturning prevention of structure on seismic ground motion to understand characteristics of restitution coefficient at collision by free rocking vibration using small structure. In this study, characteristics of restitution coefficient at collision were investigated based on vibration experiments. In case that the restitution coefficient is constant, it was difficult to fit the free rocking vibration waveforms at later part between observed and numerical analysis. However, in case that the restitution coefficient are introduced nonlinear effects, they are good agree between them.

This paper describes a fundamental study on the seismic safety margin for the isolated structure using laminated rubber bearings. The variation of the seismic response assumed in the isolated structure occurs under the superposition of "Variations in seismic response due to input ground motions" and "Error with design value accompanying manufacture of the isolation devices ". The seismic response analysis which allows to their conditions is important to assess the seismic safety margin for the isolated structure. This paper clarifies that the seismic safety margin of the isolated structure for SFR is ensured against the basis ground motions of JEAG4601 and SFR through the seismic response analysis considering the variation factors of seismic response. In addition, a relationship between the seismic safety margin and the excess probability of linearity limits is discussed using the results of seismic response analysis.

Seismic isolation system is expected to enhance the safety of critical infrastructures, such as nuclear power plants. The system has been becoming widely spread and has applied for various structures. However, in recent year, unexpected ground motion occurs frequently around the world. Ensuring and enhancing the seismic safety against the large events are essential for promoting the implementation into a system. The probabilistic risk assessment is known as a useful tool to measure the safety and used for improving the safety of nuclear power plants. To establish the methodology for estimating the seismic risk of isolation system, ultimate characteristics of isolation device, hardening and slip phenomenon, should be considered. In this paper, the effect of hardening and slip phenomenon on seismic response and risk (annual probability of failure) of isolation device and equipment is investigated. Input ground motions are incremented up to the failure of devices and equipment and seismic response simulations are carried out. As the result of simulations, it was found that the hardening effect suppresses the response displacement of isolation device, although increases the risk of equipment and piping system. Thus, we have to utilize the appropriate evaluation model that can be taken into account the hardening and slip phenomenon of isolation device.

Japan is one of the most earthquake-prone countries in the world. Accordingly, the earthquake resistance of structures is required. To secure the earthquake resistance of the structure, the application of the 3-dimensional isolation system which reduces the horizontal and vertical seismic forces is effective. However, when the vertical frequency of the 3- dimensional isolation system is low, the rocking vibration occurs. In this case, the additional devices are necessary for suppression of rocking vibration. Consequently, the 3-dimensional isolation system becomes complicated. The response in the vertical direction is reduced at the appropriate vertical stiffness of the device, furthermore the rocking vibration is negligible. The development of the 3-dimensional isolation system that would not require the devices for suppression of rocking vibration is effective for improving the earthquake resistance of general industrial equipment. Furthermore, that is effective for the spread of device. In this paper, we will investigate the applicability of a 3-dimensional isolation system that would not require the devices for suppression of rocking vibration to general industrial facility. The seismic response analysis was carried out with simultaneous horizontal and vertical input. As a result, the response of the equipment near the natural frequency of 10 Hz in the vertical direction decreases. In addition, the response of the equipment in the horizontal direction is much smaller than the input ground motion. Accordingly, 3-dimensional isolation system has high seismic isolation effect. Furthermore, the rotation angle of the equipment is about 10^-4 rad. In addition, it does not adversely affect the seismic isolation performance. Therefore, no locking suppression device is required.

Seismic isolation is an effective way to reduce damage caused by earthquakes. One of the mainstream seismic isolation systems is seismic isolation rubber. This system isolates horizontal vibration but doesn’t isolate vertical vibration. In recent years, earthquakes with large vertical vibrations have been reported. Therefore, we need the seismic isolation device that can be isolated in the vertical direction. A vertical seismic isolation device of the previous study had the problems that it was soft in the vertical direction and bad response to disturbance. Also, the horizontal vibration affects the vertical seismic isolation performance. In this study, we propose a seismic isolation device that solves the problems of the previous research and verify its characteristics and evaluate its performance. To verify its characteristics, we model the device using SimulationX. In the new seismic isolation device, the rigidity of the device can be changed by the motor drive. Also, to decrease horizontal vibration of the device, three link mechanisms are concentrically arranged at equal intervals. This device can set the natural frequency low by the negative rigidity mechanism. We performed three tests to verify its characteristics and evaluate its performance. In the damping free vibration test, we found that the amplitude difference between the experiment and the simulation is different in the upper and lower sides when we considered the equilibrium height as a reference. In the vibration test, we confirmed sufficient seismic isolation effect in multiple seismic waves. In the resonance avoidance test, we confirmed that the device avoids the resonance by the motor drive.

Recently, Seismic Isolation Building is increasing for reducing damages from earthquake. However, isolation devices in building use nonlinear characteristic positively. So that, it is difficult to verify the behavior of building by comparing analysis results and real behaviors. So, in this paper, we make new analysis model of Tokyo Denki University No.1 building in Senju, which is seismic isolation building, with all isolation elements, and we analyze it. Also, we verify new analysis results and old analysis results, which is used model of elastic deformation only. As a result, the waveforms of analysis result approach the waveforms of observation result, and precision is increased. In addition, we are developing meta-heuristic program like Particle Swarm Optimization and Differential Evolution currently, and we confirmed that they can found suitable parameter. We aim to identify parameters by using these meta-heuristic methods in the future.

In our previous study, an isolation system was proposed for not only the short-period ground motion but also the long-period one. The basic concept is that the dynamic property, which is the natural frequency, is changed by adding a spring when the amplitude of isolation table exceeds a threshold value. In the experimental equipment, there are some problems, such as, the complicated setting of clearance and the large acceleration at contact between the isolation table and additional spring. In this study, we improve the contact mechanism using the permanent magnets and soft sponges, and an isolation table for two direction is constructed. The applicability of the new isolation table is checked by using the experimental setup. As a result, the system can suppress the resonance phenomenon for two direction without large acceleration at contact time.

This paper deals with the rocking motion of cabinets and the acceleration of electronics in cabinets. In power plants or chemical plants, there are many control cabinets containing important electronics. In many cases, these cabinets are put directly. Thus, it is thought that in the worst case, cabinets may turn over by rocking motion during earthquakes and electronics may be in danger of breaking. Therefore, it is needed to develop methods that can suppress rocking motion and prevent electronics damage simultaneously. In this study, adjacent cabinets are connected with an elasto-plastic damper. The elasto-plastic damper has bilinear hysteretic characteristics and can absorb the energy of earthquake inputs. Firstly,we consider the single cabinet with electronics. The cabinet is modeled as a rotating rigid body around its corner. The internal electronics are modeled as a mass moving in the translational direction in the cabinet. This system is referred to as single cabinet system. We evaluate the maximum rocking angle of single cabinet and the maximum acceleration of electronics in single cabinet for base excitation. Next, we consider the adjacent cabinets connected by an elasto-plastic damper containing electronics. The cabinets are modeled as rotating rigid bodies. The internal electronics are modeled as masses moving in the translational direction in the cabinets. The whole system is known as a connected cabinet system. We simulate connected cabinets under the same conditions. Thus we compare the maximum rocking angle and the maximum acceleration of the single system with that of the connected system. Finally, we change the connecting position of elasto-plastic damper to understand the effects on rocking prevention and internal electronics protection. As a result,it was found that selecting the appropriate connecting position is effective in rocking prevention and internal electronics protection.

In this study, we develop an air suspension with a variable length slit restriction and make clear its dynamic characteristics. The proposed air suspension can provide the optimum equivalent damping coefficient by automatic damping adjustment mechanism. The optimum equivalent damping coefficient, which provides the minimum resonance amplitude, increases as mass of supported object increases. The damping coefficient can be varied by varying slit length of restriction. In order to vary slit length, the damping adjustment mechanism consists of a fixed plate, which has a partially circular groove, and a rotating flat plate faced to grooved plate. The variable length partially circular slit is foamed by two plates. The damping coefficient is almost proportional to an adjustment angle of the rotating flat plate in the adjustment mechanism. The adjustment angle which provides the minimum resonance amplitude can be obtained by simplified equation of the supported mass. The proposed system consists of the air suspension, two pressure gauges measuring atmospheric pressure and static pressure in the cylinder, the damping coefficient tuning mechanism, a servo motor rotating the flat plate to tune the adjustment angle and a micro-computer calculating the optimum adjustment angle using signals of the pressure gauges. Even if the mass increases up to the third of the nominal value, the minimum resonance amplitude is archived using adjustment mechanism.

The objective to extend the usable area of pipe supports up to plastic region is below; one is to enlarge the loading capacity, and the other is to add damping to piping systems using the absorption effect of seismic energy due to the elastic-plastic hysteresis property. To generate the energy absorption effect based on the elastic-plastic behavior of all pipe supports during the earthquake events, the small pipe supports are required in the small-bore piping due to the small seismic reaction. However, the structures to fix the piping on the wall are relative larger in fact. Taking into account the requirement and the specifications, a new hybrid type of elastic-plastic pipe support composed of the framework type component which is large and strong and the cantilever type component which is small and flexible is proposed in this study. The cantilever type component adds the damping by the plasticity and the framework type component protects the excessive deformation of the cantilever type component caused by the unanticipated plastic accumulation. This structure of the proposed supports is also useful for the practical design from the viewpoint of the safety design.

Plastic collapse or excessive deformation of a pipe causes double-ended failure of the pipe, that is, guillotine break, which causes a large leakage of the internal fluid. In this paper, based on the results of inelastic analysis of straight pipes, the limit of ductility factor that do not lead to plastic collapse or excessive deformation of straight pipes is clarified. Next, the relationship between yield strength and deformation of straight pipes due to seismic forces is clarified on the constant-ductility response spectra, and it indicates that double-ended failure of straight pipes is not occurred even under excessive seismic forces at nuclear power plants in Japan.

An inertia effect, which is proportional to acceleration and mass as a negative force, keeps own situation of a body during movement under the inertia low. Recently some researcher focused on the inertia effect to control vibration. In previous paper the authors developed a vibration control device which is having variable moment of inertia by MagnetoRheological fluid inside a flywheel. Ferrite particles of the MR fluid are clustered when magnetic field is applied by 4 electromagnets to the flywheel. Then the radius of gyration of the flywheel, which depends on the moment of inertia, is changed, the vibration control device can have a variable moment of inertia. It was clear that the inertia mass effect was varied as higher current, and vibration control for the earthquakes was confirmed numerically and experimentally. In this paper the vibration control device using 8 electromagnets is updated from the prototype in order to get more inertia effect stably. Magnetic field in case of 8 electromagnetic poles was analyzed by FEM, and resisting force characteristics of the new device were investigated.

Oil dampers are indispensable devices for vibration suppression, but their nonlinear behavior makes it difficult to theoretically determine their damping characteristics. For that reason, the damping coefficient for oil dampers has conventionally been handled by introducing an experimentally determined constant into theoretical equations. In other words, the characterization of oil dampers has ultimately relied on experimentation. Fortunately, if the damping oil is a Newtonian Žuid, the Navier-Stokes equations are able to accurately describe its movement. In our previous study,the Navier-Stokes equations were solved using the finite difference method and the damping coefficient was accurately calculated for an annular-channel-type oil damper. In this paper, we report the damping and added mass characteristics of the commonly used oil dampers, the piston-hole-type and bypass-pipe-type dampers, obtained using the finite difference method as in the previous report. The most basic design formula indicates that the damping coefficients for these dampers are the same when the Žow paths are equal in length; however, it was demonstrated in this study that the damping characteristics of these dampers differ greatly depending on the shape of the convective vortex generated in the cylinder. The immersed boundary method was used in the present numerical analysis because the boundary of the Žuid to be analyzed is surrounded by fixed and moving walls.

In this paper, the damping force obtained by stirring the granular material was investigated both theoretically and experimentally. In a theoretical approach, the damping force was calculated using the discrete element method. It was found that an analytical solution is provided to estimate the relationship between the damping torque and the frequency of the blade. In an experimental approach, the effect of the vessel shape on the damping force was investigated. In this study, uniformly sized spherical particles were used as the granular materials. Some stepped parts were provided on the bottom of the vessel to increase the damping force. The effect of the stepped parts on the damping force was confirmed.

The granular material damper performs vibration reduction by converting the kinetic-energy that control on vibration object vibrates into thermal energy occurring by impact with the friction mark between the particle and the control on vibration object. Because the mechanism is simple, advantages include ease of the installation. On the other hand, it is difficult to predict the control on vibration performance by the characteristics of the particle to enclose and discontinuous vibration behavior. Therefore this research predicted the attenuation performance from simulation of the particle behavior using the discrete element method about the control on vibration of the granular material damper of the slight infinitesimal grain which paid its attention to basic particle size of the microsize.

The granular damper enables damping of vibration by enclosing a plurality of particles in the structure. The vibration damping principle of the granular damper is the dissipation of energy due to friction between particles. Since this damper is easy to install, it has been applied research as a vibration control structure for various machines. In order to ensure vibration damping performance and perform design, it is necessary to predict the frictional force between particles and the collision force with a container by simulation. The purpose of this research is to propose the evaluation method of the vibration damping performance of the granular damper and the prediction method by the discretized element method using the fine particles with the basic particle diameter of 100μm or less. As for the experimental method, various evaluations have been made possible by a simple test method in which fine particles are enclosed in a metal plate. With this test method, we succeeded in obtaining a good damping effect even with a granular damper with a particle size of 100 μm or less, and finding the control factors necessary for design.

In this study, influence that the damping force properties of the damper using particle assemblage received from flow rate of the inflow air were investigated experimentally. Zirconia balls of 0.5 mm in diameter were prepared as the particle. The damper was installed in the horizontal direction. The air was poured into the damper from bottom side holes, and the air was poured into outside from upper side holes of the damper. The forced displacement of the sine wave was given to the damper. The damping forces and displacements of the damper were measured. When the flow rate of the air is low, the damping force of the damper decreased as the flow rate is increased. On the other hand, when the flow rate of the air is high, the damping force of the damper increased as the flow rate is increased.

Recent years, high-performance and compact vibration isolator has been demanded with the advancement of precise technology. Among various vibration isolators, a passive vibration isolator is the most commonly adopted form due to its simplicity, stability and low cost. In the previous studies, the authors have proposed a simple and compact passive vibration isolator for the vertical direction using a post-buckled shape memory alloy (SMA) beam. This isolator achieved a low natural frequency assuring high static stiffness by utilizing the negative tangent stiffness of a post-buckled SMA beam. In this study, the restoring force is investigated by the Finite Element Analysis in which the phase transformation of the post-buckled SMA was taken in account to understand deeply the relationship between negative stiffness and phase transformation. The results show that the phase transformation from austenite phase to martensite phase and reversible transformation is associated to the appearance of negative stiffness. Also, in the restoring force of a SMA beam subjected to reciprocating motion in its post-buckled state was analyzed. As the result, it was found that the restoring force converged to a certain force when SMA was subjected to reciprocating motion．In future research, It is necessary to investigate dynamic mechanical characteristic and validate the performance of the isolator taking in account the phase transformation.