In order to understand rocking vibration characteristics of a small structure installed on the seismic isolation system using sliding mechanical system under various condition, we have performed vibration test and proposed a numerical analysis model using 2-DOF. From results of vibration test using sine waves and observed seismic ground motions as inputs, it was indicated that the rocking vibration and overturning behavior of a structure can be suppressed by setting the dynamic friction coefficient. The rocking vibration and overturning behavior of the structure could be suppressed by the dynamic friction coefficient on the small seismic isolation system in which the small friction coefficient that could not reach the overturning limit acceleration amplitude of the structure was set. In case of input as sine waves and seismic ground motions, it was good agreement between response wave forms in vibration test and numerical analysis. Therefore, the numerical model using 2-DOF proposed in the study is effective to evaluate vibration behavior of small structure installed on the seismic isolation systems with sliding mechanical system.

Welding is used as a joining method in the construction of many structures. Residual stress is generated near the bead because of locally given heat. It is well known that it degrades fatigue strength. Especially, it is a cause of stress corrosion cracks in stainless steel. Since reduction methods, stress-relief annealing and shot peening are widely used, reduction methods of residual stress have been studied. However, these methods require special equipment and are time-consuming. The authors have proposed a method using vibrations during welding and shown the effectiveness of the method in rolled steel for general structures. On the other hand, the authors have also investigated the effectiveness of the method on stainless steel which is used for important structures. However, the experimental conditions were not the same. In this paper, the reduction of residual stress on build-up welded SUS304 and SS400 specimens were compared in the same experimental conditions and the effects of material properties on the method were investigated. The experiment is conducted for different amplitudes of the ultrasonic vibration load and without vibration load. It is concluded that the reduction rate for SUS304 is greater than that for SS400 and that the greater the amplitude of the ultrasonic vibration load, the greater the reduction rate. Statistical values of residual stress were obtained and there were significant differences in the mean values between each amplitude of ultrasonic vibration load. Additionally, the effectiveness of the method has also been verified. The experimental results were examined by the simulation method using a model considering plastic deformation caused by ultrasonic vibration load. It is found that residual stress is reduced using ultrasonic vibration load during welding.

The sliding surface in the mechanical system is required to move smoothly and stop at the target position. The sliding surface can move and stop by applying adequate friction force. The friction force is controlled by developing technology creating small textures on the surface at a few to a few hundred micrometer intervals. If friction force is reduced by applying this technology to large area sliding surfaces of generators, machine tools and so on, the machining effect is drastically improved. On the other hand, ultrasonic vibration is used in many manufacturing fields. It is well known that surface roughness is improved and stress is reduced using ultrasonic vibration. In this study, knurling is focused on creating texture. Machining technology is developed to create wear-resistant texture on large area sliding surfaces with high precision and efficiency using ultrasonic vibration during knurling. In this paper, the effect of ultrasonic vibration on creating texture using knurling is examined by the fundamental experiment. In the experiment of making a groove on the surface with an indenter using a 2-dimensional table, pressing force and friction force are measured. These forces are reduced using ultrasonic vibration.

Welding is a joining method in used for various structures. Since heat is applied locally to the material in welding, tensile residual stress is generated near the bead, causes the stress corrosion cracking in stainless steel. Therefore, it is important to develop a method of welding residual stress reduction. We have proposed the method loading ultrasonic vibration for base material during the welding. The advantage of this method is to reduce the residual stress easily in short time. In this study, effects of acceleration amplitude on welding residual stress reduction using block material SUS304 is investigated-

Welding is a joining method used for many structures, and to melt the material applying heat locally.Since the tensile residual stress is generated in the process of cooling and hardening, and make less the fatigue limit of base material.Therefore, a method of welding tensile residual stresses without special devices is developing using ultrasonic vibration load.According to previous studies [1][2], they indicated that it was an effective method to reduce the welding residual stress using ultrasonic vibration load in case of built-up welding with metal block or thin metal sheets of rolled steel for general structure SS400.[3] Since the melting point of stainless steel used for important structures such as a nuclear reactor is higher temperature than that of rolled steel for general structure, it expects that the welding residual stress of stainless steel is higher than that of rolled steel for general structure.The residual stress is one of the reasons that is caused stress corrosion cracking.Therefore, it is important to develop a method of welding reducing residual stress in stainless steel.In this study, the effectiveness of welding residual stress reduction method using ultrasonic vibration load is investigated for austenitic stainless steel SUS304.Comparing results of welding residual stress between with and without ultrasonic vibration load, it was reduced by the wave of welding with ultrasonic vibration load.The reduction rate between the ultrasonic vibration load at the frequency of 36 kHz and of 58 kHz was almost same.However, comparing the reduction rate between acceleration amplitude of 2000m/s² and 5000m/s², the case of 5000m/s² is greater the residual stress reduction.From these results, the method of welding loaded the ultrasonic vibration at the frequency of 36 kHz and of 58 kHz can reduce welding residual stresses for austenitic stainless steel SUS304.Comparing effects between the acceleration amplitude of the ultrasonic vibration load and the frequency, the acceleration amplitude has a greater effect on the residual stress reduction.

Welding is used in many structures. Since heat is applied locally to the material in welding, tensile residual stress is generated near the bead, causes the stress corrosion cracking in stainless steel. We have developed welding residual stress reduction for structural rolled steel using ultrasonic vibration load. In this study, we apply this method for stainless steel SUS304 block material, and measure welding residual stress. Comparing the results of residual stress measurement between with and without ultrasonic vibration load, effectiveness of this method on stainless steel is investigated. As a result, this method can reduce welding residual stress in stainless steel. The reduction rate in case with acceleration amplitude of 5000m/s² is greater than one in case with acceleration amplitude of 2000m/s². From the t-test results, significant differences of welding residual stress reduction between them were confirmed. In case of ultrasonic vibration load with acceleration amplitude of 2000m/s2, welding residual stress was reduced 16% compared to no load. In case of 5000m/s2, it was reduced to 30%.

Welding is the joining method using locally given heat. Residual stress is generated near the bead and it degrades fatigue strength. A reduction method of residual stress in a short duration and low costs using ultrasonic vibration load during welding has been investigated. Build up welding was done for a block metal that is rolled steel for general structures SS400 by this method, and was measured residual stress by X-ray residual stress measurement device. In this study, effectiveness of ultrasonic vibration load for welding is investigated.

Various types of devices have been developed to reduce seismic response of the mechanical systems. Base isolation system is one of them. In such devices, friction characteristic is used. The authors have developed a base isolation system with friction for relatively small mechanical system. In ordinary case, response of mechanical system decreases with the increase of friction coefficient. However, in the experiment to examine the effectiveness of base isolation system, it is found that acceleration response takes minimum value at some friction coefficient. In this paper, experimental results are examined using a simplified model. As earthquake excitations, some types of random vibration are used. Responses of the mechanical system are obtained from moment equations using the equivalent linearization method. It is demonstrated that acceleration response takes minimum value at some friction coefficient in some conditions.

Extended Abstract Small exhibits displayed in the museum had been overturned and damaged by big seismic ground motion [1], [2]. In order to reduce the risk of seismic damage, some small base isolation systems for small exhibits, that are possible to install inside buildings, have been developed [3]-[5]. However, their mechanisms have been complicated and cost too much, the system is not popular in the small-scale museums. Therefore, we have proposed a simple seismic isolation system for exhibits in the museums [6]. In order to investigate effectiveness of the system, dynamic characteristics of the system are investigated by vibration experiment. The simple isolation system consists of two aluminium metal plates coated with solid lubricant. A large lower plate is 500×500 mm size, a small upper one is 125×125 mm size. A friction coefficient between two plates is 0.12. Since mechanisms of the system are quite simple, it is easy to maintain it. To confirm effectiveness of the system, the excitation experiment was performed using a seismic ground motion of Mid Niigata Prefecture Earthquake in 2004 recorded at K-NET NII019 (K-NET Ojiya) as the input wave. The peak acceleration amplitude on the input wave indicated 1313 Gal, the peak response amplitude on the system was 221 Gal. Since it has reduced to about 1/6 against the peak acceleration amplitude on the input wave, the system is effective to reduce the response on seismic ground motion. Next, the effectiveness of overturning prevention for small exhibits was investigated by excitation experiment. In the experiment, a vase that overturing acceleration amplitude is 400 Gal, was installed on the upper plate of system. The response waveform on the upper plate was enough reduced. Although a part of the response waveform on the top of the vase identifies such as pulse, it indicates that the vase generated rocking motion. And the vase did not overturn. In fact, the peak response acceleration amplitude on the upper plate is 221 Gal, is lower the overturning acceleration of the vase. The system is effective to prevent overturning of small exhibits in the museums by seismic ground motion.

Sliding surface in mechanical system is required to move smoothly and stop at target position. Sliding surface can move and stop by applying adequate friction force. It is necessary to develop machining technology to create texture with high precision and efficiency. On the other hand, ultrasonic vibration is used in many manufacturing fields. It is well known that surface roughness is improved and stress is reduced using ultrasonic vibration. In this study, machining technology creating wear resistant texture on large area sliding surface with high precision and efficiency using ultrasonic vibration during knurling is developed. The technology can be applied to the dampers and the base isolation systems for reduction of seismic response of the structures In this paper, the effect of ultrasonic vibration is examined by the fundamental experiment. In some of those devices, friction characteristics are an important factor for controlling their efficiency. In the experiment making a groove on the surface with an indenter using a 2 dimensional table, pressing force and friction force are measured. These forces are reduced using ultrasonic vibration. Pressing experiment making texture on the surface is also made. Deeper and clearer marks are formed using ultrasonic vibration during knurling.

Sliding surface in mechanical system is required to move smoothly and stop. Sliding surface can move and stop by giving adequate friction force. Friction force is controlled by developing technology creating small texture on the surface with a few micrometer to a few hundred micrometer interval. If friction force is reduced by applying the technology to large area of sliding surface of airplane, generator and machine tool so on, machining effect is rapidly improved. It is necessary to develop machining technology to create texture with high precision and efficiency. On the other hand, ultrasonic vibration is used in many manufacturing fields. It is well known that surface roughness is improved and reduce stress using ultrasonic vibration. In this study, machining technology creating wear resistant texture on large area sliding surface with high precision and efficiency using ultrasonic vibration during knurling is developed. In this paper, effect of ultrasonic vibration is examined by the fundamental experiment. A horn to amplify ultrasonic vibration is designed and made. Frequency of ultrasonic vibration is measured and it is found that desired frequency is available. In the experiment making a groove on the surface with indenter using 2 dimensional table, pressing force and friction force are measured. Pressing force and friction force are reduced using ultrasonic vibration.

Sliding surface in mechanical system is required to move smoothly and stop at target position. Sliding surface can move and stop by applying adequate friction force. Friction force is controlled by developing technology creating small texture on the surface with a few to a few hundred micrometer intervals. If friction force is reduced by applying this technology to large area sliding surface of airplanes, generators and machine tools, so on, the machining effect drastically improves. It is necessary to develop machining technology to create texture with high precision and efficiency. On the other hand, ultrasonic vibration is used in many manufacturing fields. It is well known that surface roughness is improved and stress is reduced using ultrasonic vibration. In this study, machining technology creating wear resistant texture on large area sliding surface with high precision and efficiency using ultrasonic vibration during knurling is developed. In this paper, effect of ultrasonic vibration is examined by the fundamental experiment. A horn to amplify ultrasonic vibration is designed and made. Frequency of ultrasonic vibration is measured and it is found that desired frequency is available. In the experiment making a groove on the surface with an indenter using a 2 dimensional table, pressing force and friction force are measured. These forces are reduced using ultrasonic vibration. Pressing experiment making texture on the surface is also made. Deeper and clearer marks are formed using ultrasonic vibration during knurling for the specimen made of copper.

It is important to understand characteristics of rocking vibration related to overturning small structures inside buildings. In order to investigate the behavior of rigid body by rocking vibration, excitation experiment by free rocking vibration was conducted. From waveforms of free rocking vibration, the natural period has been reduced with time, and has been depend on indicial angle. However, it is difficult to explain under an assumption that the restitution coefficient is constant. Using the restitution coefficient that depend on collision velocity to the basement, it was good agreement between experimental and analytical waveforms.

In order to investigate the effects of exhibits fixed by nylon gut in the museum on seismic ground motion, strength test on nylon gut and excitation experiment of specimen fixed with nylon gut have been performed. In case of weak tension on the nylon gut, since the nylon gut has been extended by the load, the specimen fixed with nylon gut was generated a rocking vibration, and sometime the bottom of specimen was slide. Finally, it has been overturned by shaking. However, in case of strong tension, although the weak rocking vibration was generated, it has not been overturned. The tension on the nylon gut is one of important factor.

Welding is the joining method using locally given heat. Residual stress is generated near the bead and it degrades fatigue strength. There are methods such as heat treatment and shot peening as a method of reducing the residual stress. However these require special equipment and a lot of time. The authors have proposed a reduction method of residual stress in a short duration and low costs using ultrasonic vibration during welding. As a result, the residual stress is reduced by butt welding while applying ultrasonic vibration in SUS304 stainless steel. In this research, effects of vibration frequency on fill welding using SUS304 stainless steel were performed.