Seiji Kitamura
Japan Nuclear Cycle Development Institute
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Journal of Pressure Vessel Technology-transactions of The Asme | 2009
Keisuke Minagawa; Satoshi Fujita; Seiji Kitamura; Shigeki Okamura
In Japan, mechanical structures installed in nuclear power plants, such as piping and equipment, are usually designed statically in an elastic region. Although these mechanical structures have sufficient seismic safety margin, understanding the ultimate fatigue endurance is very important in order to improve the seismic safety reliability for unexpected severe earthquakes. Moreover, clarifying a margin of seismic resistance of mechanical structures that suffered a severe earthquake is being required. In this study, the energy balance equation that is one of valid methods for structural calculation is applied to the above-mentioned issues. The main feature of the energy balance equation is that it explains accumulated information of motion. Therefore the energy balance is adequate for the investigation of the influence of cumulative load such as seismic response. The investigation is implemented by forced vibration experiments. The experiment models are simple single-degree-of-freedom models that are made of stainless steel and carbon steel. In the experiment, random waves having predominant frequency similar to natural frequency of the experimental model are input in order to obtain adequate response not only in the elastic region but also in the plastic region. As a result, experimental models vibrate under resonance condition, so response acceleration is approximately seven times as big as the input. The excitation is continued until the experimental models fracture, and is carried out with various input levels. In the experiment, models suffered cracks at the bottom end, and fractured finally. As a result, input energy for failure increases as time for failure. In other words, more input energy for failure is needed in case of small input. Moreover the correlation between increment in input energy and input energy for failure is investigated. It was confirmed that input energy for failure is inversely proportional to increment in input energy per unit time. Additionally energy for failure of stainless steel is about twice as big as carbon steel. The correlation between fatigue failure and energy is confirmed from the vibration experiment. Therefore it is expected that time for fatigue failure can be evaluated by the energy balance equation.
Journal of Pressure Vessel Technology-transactions of The Asme | 2002
Takaaki Sakai; Masaki Morishita; Koji Iwata; Seiji Kitamura
Experimental validation of the design guideline to prevent the failure of a thermometer well by vortex-induced vibration is presented, clarifying the effect of structure damping on displacement amplitudes of a cantilever cylinder. The available experimental data in piping are limited to those with small damping in water flow, because of the difficulty in increasing structure damping of the cantilever cylinders in experiments. In the present experiment, high-viscosity oil within cylinders is used to control their structure damping. Resulting values of reduced damping (C n ) are 0.49, 0.96, 1.23, 1.98, and 2.22. The tip displacements of the cylinder induced by vortex vibration were measured in the range of reduced velocity (V r ) from 0.7 to 5 (Reynolds number is 7.8×10 4 at V r = 1). Cylinders with reduced damping 0.49 and 0.96 showed vortex-induced vibration in the flow direction in the V r >1 region. However, in cases of reduced damping of 1.23, 1.98, and 2.22, the vibration was suppressed to less than 1 percent diameter It is confirmed that the criteria of V r 1.2 for the prevention of vortex-induced vibration is reasonably applicable to a cantilever cylinder in a water flow pipe.
ASME 2002 Pressure Vessels and Piping Conference | 2002
Seiji Kitamura; Masaki Morishita
A structural concept of a vertical component isolation system for fast reactors, assuming a building adopting a horizontal base isolation system, has been studied. In this concept, a reactor vessel and major primary components are suspended from a large common deck supported by isolation devices consisting of large coned disk springs. A series of experiments using a simple model for the confirmation of the isolation effect, and a case study of vertical isolation device and plant layout are shown in this paper.© 2002 ASME
Jsme International Journal Series B-fluids and Thermal Engineering | 2001
Takaaki Sakai; Koji Iwata; Masaki Morishita; Seiji Kitamura
Journal of Structural and Construction Engineering (transactions of Aij) | 2014
Seiji Nagata; Shuichi Yabana; Kenji Kanazawa; Kazuta Hirata; Katsuhiko Umeki; Satoru Inaba; Takeshi Sano; Takashi Nakamura; Takuya Anabuki; Kazutaka Shirai; Seiji Kitamura; Masaki Morishita
Dynamics and Design Conference : D & D | 2013
Tomoyoshi Watakabe; Naoaki Kaneko; Shigekazu Aida; Akihito Otani; Kazuyuki Tsukimori; Makoto Moriizumi; Seiji Kitamura
The Proceedings of the Materials and Mechanics Conference | 2012
Naoaki Kaneko; Seiji Kitamura; Noboru Jinbo; Takumi Mizutani; Akihito Otani
The Proceedings of the Dynamics & Design Conference | 2012
Hajime Seki; Satoshi Fujita; Toshio Omi; Keisuke Minagawa; Seiji Kitamura; Tomoyoshi Watakabe
The Proceedings of Mechanical Engineering Congress, Japan | 2012
Hajime Seki; Satoshi Fujita; Toshio Omi; Keisuke Minagawa; Seiji Kitamura; Tomoyoshi Watakabe
The Proceedings of Conference of Kanto Branch | 2012
Hajime Seki; Satoshi Fujita; Keisuke Minagawa; Takahiro Yamanaka; Seiji Kitamura; Tomoyoshi Watakabe