Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Okajima, Satoshi; Wakai, Takashi
Nihon Kikai Gakkai 2017-Nendo Nenji Taikai Koen Rombunshu (DVD-ROM), 5 Pages, 2017/09
It was reported that the long distance travel of temperature distribution causes a new type of thermal ratcheting, even in the absence of primary stress. In this paper, based on the results of inelastic finite element analyses, we investigated saturation behavior of thermal ratcheting strain due to long range travel of temperature distribution. As a result, we revealed that the long distance travel of temperature distribution generates plastic strain distribution made maximum at the central part. Because of the shape of the generated strain distribution, the residual stress accumulates even at the central part of the region passed through the temperature distribution. In the case with excessive long traveling of temperature distribution, the region with plastic deformation extended to the surrounding region. Otherwise, sufficient magnitude of residual stress to cause shakedown behavior accumulated on entire region, and the accumulation of the plastic strain saturated.
Nishi, Hiroshi
Fusion Engineering and Design, 81(1-7), p.269 - 274, 2006/02
Times Cited Count：4 Percentile：30.68(Nuclear Science & Technology)Tensile strength of the diffusion bonded joint was as large as that of Alumina dispersion-strengthened copper (DS Cu), however, the Charpy absorbed energy of the joint was considerably lower than that of DS Cu. Instrumented Charpy impact test and slow-bend Charpy test of diffusion bonded joints were performed to clarify the degradation of Charpy absorbed energy. Elasto-plastic analyses were also carried out in order to study the deformation behavior of the tensile and V-notched specimens for joints. As the results, the fracture behaviors of the impact and slow-bend tests were almost the same. Elasto-plastic analyses showed that the maximum strain occurred at the DS Cu apart from the interface for tensile specimen, however, the strain concentrated at the DS Cu near the interface for the notched specimen. This strain concentration arose from the mechanical heterogeneity between stainless steel and DS Cu in the bonded zone and attributed to the degradation of the absorbed energy of the joints.
Hazama, Osamu; Nakajima, Norihiro; Post, P.*; Wolf, K.*
Proceedings of 8th US National Congress on Computational Mechanics (USNCCM-8) (CD-ROM), 1 Pages, 2005/07
Computational science has always played an import role in nuclear engineering because it is quite difficult, if not impossible, to carry out experiments on the actual full-scale reactors in operation. We have been developing a numerical simulation infrastructure for carrying out numerical experiments on the virtual reactors constructed within computers. In order to understand the physical behavior of a reactor, interactions among various physial phenomena must be considered and understood. Therefore, a generic coupler has been developed to connect various software and hardware for the purposes of coupled simulations. Since this type of simulation requires large amount of computational resources, the coupler development is carried out on the ITBL GRID infrastructure. The development of this coupler and its applications to parallel and distributed coupled simulations with future development plans are reported.
Hazama, Osamu; Nakajima, Norihiro
Keisan Kogaku Koenkai Rombunshu, 10(1), p.259 - 260, 2005/05
It is impossible to carry out a controlled laboratory experiments on an operational full-scale power plant. Therefore, construction of a testbed to assess the safety of such systems by numerical means is believed to be meaningful. At CCSE/JAERI, a project to develop a numerical testbed to assess the safety of nuclear reactors have been begun. Simulations of such complex systems will inevitably require tremendous amount of computational resources. Therefore, the numerical testbed is constructed on the ITBL Grid middleware. A prototype of a generic software coupling interface was developed to couple various simulation software within the ITBL Grid environment to execute large-scale multi-disciplinary simulations on the testbed. This coupler and its application to some fluid-structure problems will be illustrated.
Hazama, Osamu; Nakajima, Norihiro
Proceedings of 6th MpCCI User Forum, p.76 - 77, 2005/05
In order to accurately solve complex physical phenomena, interactions of various phenomena must be considered, which makes simulations multi-disciplinary. We have been developing a virtual nuclear reactor simulator on the ITBL Grid infrastructure in order to assess the safety of the nuclear reactors. This simulator system allows for numerical experiments on the full-scale and fully operational virtual nuclear reactors which is not possible in real-life experiments. In order to clarify various complex physical phenomena within the reactors, multi-disciplinary simulations, which are computationally demanding, are required. We have been developing a software to allow concurrent use of arbitrary combination of hardware and software to realize a multi-disciplinary simulation system on the ITBL. We have used STAMPI, developed by CCSE/JAERI, and MpCCI, developed by Fraunhofer SCAI, to construct the system. The system is now functional on the ITBL and will be introduced.
Hazama, Osamu; Nakajima, Norihiro; Hirayama, Toshio; Post, P.*; Wolf, K.*
IWACOM, P. 161, 2004/11
The numerical methods and computational hardware of today allow for studies on multi-disciplinary simulations. We have been developing an "integrated numerical simulation system" to solve coupled simulation problems under meta-computing environments. The system aims to construct a competent coupler for carrying out multi-disciplinary simulations by allowing concurrent execution of arbitrary simulation codes on different computers in parallel. The effectiveness of this system infrastructure is illustrated through its applications to fluid-structure interactive problems.
Atanasiu, G. M.*; Hazama, Osamu; Guo, Z.; Yagawa, Genki*
Proceedings of 2nd International Conference Lifetime Oriented Design Concepts (ICLODC 2004), p.449 - 458, 2004/03
Some strategies in monitoring the structural seismic performance for a class of RC multistory buildings using linear and nonlinear dynamic analysis. New concepts and visions, considering the seismic input models based on probabilistic hazard level, will be presented. Numerical simulations of RC structures with different topologies are carried out as case studies, to search for a suitable strategy of seismic monitoring based on structural performance. For comparison, equivalent single degree of freedom models are also taken into account. The seismic input is based on the 1994 Northridge earthquake acceleration time histories. For comparison, the unscaled Kobe ground motion were also considered as input.
Hazama, Osamu; Guo, Z.
Proceedings of International Conference on Supercomputing in Nuclear Applications (SNA 2003) (CD-ROM), p.119 - 120, 2003/09
In order for the numerical simulations to reflect textquotedblleft real-worldtextquotedblright phenomena and occurrences, incorporation of multidisciplinary and multi-physics simulations considering various physical models and factors are becoming essential. However, there still exist many obstacles which inhibit such numerical simulations. For example, it is still difficult in many instances to develop satisfactory software packages which allow for such coupled simulations and such simulations will require more computational resources. A precise multi-physics simulation today will require parallel processing which again makes it a complicated process. Under the international cooperative efforts between CCSE/JAERI and Fraunhofer SCAI, a German institute, a library called the MpCCI, or Mesh-based Parallel Code Coupling Interface, has been implemented together with a library called STAMPI to couple two existing codes to develop an textquotedblleft integrated numerical simulation systemtextquotedblright intended for meta-computing environments.
Hazama, Osamu; Guo, Z.
Keisan Kogaku Koenkai Rombunshu, 8(2), p.759 - 760, 2003/05
no abstracts in English
Takada, Shoji; Futakawa, Masatoshi; *; Iyoku, Tatsuo
Proc. of the 12th Int. Conf. on Structural Mechanics in Reactor Technology,Vol. K; SMiRT 12, p.103 - 108, 1993/00
no abstracts in English
Katsuyama, Jinya; Yamaguchi, Yoshihito; Kaji, Yoshiyuki; Yoshida, Hiroyuki
no journal, ,
no abstracts in English
Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Tsuruta, Osamu; Suzuki, Yoshio
no journal, ,
Japan Atomic Energy Agency has been developing the three-dimensional virtual shaking table for earthquake-resistant evaluations in the atomic energy facilities. It is to realize an earthquake proofing reliability examination by analyzing the earthquake-resistant of the large structure on a computer. This is the trial that is going to realize a virtual shaking table examination such as difficult size of the original structures or nuclear power generation facilities while driving on a computer. Authors develop the structure analysis cord of the assembling structure so called FIESTA (Finite Element Structural Analysis for Assembly) as one of the core functions. This is the details analytical method that paid its attention to the behavior between the part of the assembling structure as one means to perform the earthquake-resistant evaluations for such as atomic energy facilities. In this report, it is reported the way of time history response analysis by assembly structural analysis.
Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Suzuki, Yoshio
no journal, ,
Quality Assurance is an issue for computational science and engineering. It is well discussed in verification and validation for Simulation. In finite element analysis, it is a problem whether the finite element discretization is appropriate or not. Also, algorithmic choice prepared variously by the recent R&D discipline that become the problem which one to take. An experiment was performed for the static analysis and natural frequency analysis to confirm how uncertainty is revealed. As a result, by means to compare accuracy of the calculation precision that utilized a parallel environment, the numerical experiment reconfirmed that the estimate of the calculation solution was possible.
Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Suzuki, Yoshio
no journal, ,
Facilities in nuclear industry are known as large structures consisting of components more than 10 million. A method to analyze an assembly by gathering its components data has been introduced. This paper discusses how to understand certainty in results of assembly structural analysis. Numerical results are discussed with K, computer.
Nakajima, Norihiro; Nishida, Akemi; Iigaki, Kazuhiko; Sawa, Kazuhiro
no journal, ,
An tried-out for the comparison with the observation and computational data is introduced. The simulation is carried out on the K by using an assembly structural analysis, so named FIESTA. The observation were determined in the high temperature engineering test reactor.
Nakajima, Norihiro
no journal, ,
The artifact deteriorates and goes. Since many are used under the loaded condition, dynamic analyses are ought to be studied in the designing process. While dynamic analyses give data in step by step, these data needs to be analyzed, efficiently. For data analyses, both deduction and induction methodology should be provided. In the research in JAEA for the digital vibration table, it is developing a methodology for a data analysis based upon abduction.
Takamizawa, Hisashi; Yamaguchi, Yoshihito; Katsuyama, Jinya; Nishiyama, Yutaka
no journal, ,
no abstracts in English
