Development of the buckling evaluation method for large scale vessels in fast reactors by the testing of Grade 91 steel and austenitic stainless steel vessels subjected to horizontal and cyclic vertical loading

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Ando, Masanori; Okajima, Satoshi

Proceedings of ASME 2023 Pressure Vessels and Piping Conference (PVP 2023) (Internet), 8 Pages, 2023/07

Buckling evaluation methods capable of evaluating elasto-plastic buckling under axial compression, bending, and shear loads are required for cylindrical vessels of fast reactors to cope with thinning due to increasing diameter and application to the seismic isolation design against huge seismic ground motion. In this study, in order to confirm the applicability of the proposal evaluation method, several buckling tests and FE analyses were carried out using the specimens made of Gr.91 and austenitic stainless steel. The buckling modes and strength data in the load region where the interaction of cyclic axial compression, bending and shear buckling could occur were examined. As a result, it was confirmed that the proposal evaluation method estimated the buckling load in the tests conservatively.

Dislocation core structure and motion in pure titanium and titanium alloys; A First-principles study

Tsuru, Tomohito; Itakura, Mitsuhiro; Yamaguchi, Masatake; Watanabe, Chihiro*; Miura, Hiromi*

Computational Materials Science, 203, p.111081_1 - 111081_9, 2022/02

https://doi.org/10.1016/j.commatsci.2021.111081

The deformation mode of some titanium (Ti) alloys differs from that of pure Ti due to the presence of alloying elements in -phase. Herein, we investigated all possible slip modes in pure Ti and the effects of Al and V solutes as typical additive elements on the dislocation motion in -Ti alloys using density functional theory (DFT) calculations. The stacking fault (SF) energies in possible slip planes indicated that both Al and V solutes reduce the SF energy in the basal plane and, in contrast, the Al solute increases the SF energy particularly in the prismatic plane. DFT calculations were subsequently performed to simulate dislocation core structures. The energy landscape of the transition between all possible dislocation core structures and the barriers for dislocation glide in various slip planes clarified the nature of dislocation motion in pure Ti. (i) the energy of prismatic core is higher than most stable pyramidal core, and thereby dislocations need to overcome the energy barrier of the cross-slip (22.8 meV/b) when they move in the prismatic plane, (ii) the energy difference between the prismatic and basal cores is larger (127 meV/b), that indicates the basal slip does not activate, (iii) however, the Peierls barrier for motion in the basal plane is not as high (16 meV/b). Direct calculations for the dislocation core around solutes revealed that both Al and V solutes facilitate dislocation motion in the basal plane by reducing the energy difference between the prismatic and basal cores. The effect of solutes characterizes the difference in the deformation mode of pure Ti and -Ti alloys.

Development of the buckling evaluation method for large scale vessel by the testing of Gr.91 vessel subjected to horizontal and cyclic vertical loading

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Ando, Masanori; Miyazaki, Masashi

Proceedings of ASME 2021 Pressure Vessels and Piping Conference (PVP 2021) (Internet), 9 Pages, 2021/07

Buckling evaluation methods capable of evaluating elasto-plastic buckling under axial compression, bending, and shear loads are required for cylindrical vessels of fast reactors to cope with thinning due to increasing diameter and application to the seismic isolation design against huge seismic ground motion. In this study, in order to confirm the applicability of the proposal evaluation method, several buckling tests and FE analyses were carried out using the specimens made of Modified 9Cr-1Mo steel. The buckling modes and strength data in the load region where the interaction of cyclic axial compression, bending and shear buckling could occur were examined. As a result, it was confirmed that the proposal evaluation method estimated the buckling load in the tests conservatively. Moreover, a series of finite element analyzes using a model with residual stress due to welding revealed that the effect of residual stress on buckling strength is negligible in the evaluation method.

Study on the seismic buckling evaluation method for Mod. 9Cr-1Mo steel cylindrical vessel

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Kubo, Koji*; Sato, Kenichiro*; Wakai, Takashi; Shimomura, Kenta

Nihon Kikai Gakkai M&M 2017 Zairyo Rikigaku Kanfarensu Koen Rombunshu (Internet), p.591 - 595, 2017/10

no abstracts in English

First test results for the ITER central solenoid model coil

Kato, Takashi; Tsuji, Hiroshi; Ando, Toshinari; Takahashi, Yoshikazu; Nakajima, Hideo; Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; Kawano, Katsumi; Oshikiri, Masayuki*; et al.

Fusion Engineering and Design, 56-57, p.59 - 70, 2001/10

https://doi.org/10.1016/S0920-3796(01)00235-6

no abstracts in English

Plasma real-time control system for advanced tokamak operation scenarios in JT-60

Kurihara, Kenichi; Kawamata, Yoichi; Akiba, K.*; Miura, Yushi; Akasaka, Hiromi; Adachi, H.*; Hoshi, Y.*; Fukuda, Takeshi; Oikawa, Toshihiro

IEEE Transactions on Nuclear Science, 47(2), p.205 - 209, 2000/04

no abstracts in English

None

Miura, Makoto; Honda, Yutaka*; Omori, Takuro; Kaneko, Hiromitsu; ; Yato, Tadao*; Tanaka, Yasumasa; Konashi, Kenji

PNC TN841 79-11, 118 Pages, 1979/02

PNC-TN841-79-11.pdf:10.71MB

no abstracts in English

Heterogeneous nano-structures and specific mechanical properties of heavily cold-rolled stainless steels

Miura, Hiromi*; Kobayashi, Masakazu*; Todaka, Yoshikazu*; Watanabe, Chihiro*; Aoyagi, Yoshiteru*; Oba, Yojiro

no journal, , 

Heavy cold rolling can develop unique mixed structures with nano-lamellar, shear bands and mechanical nano-twins in various kinds of stainless steels. In particular, "eye-shaped" twin domains developed in phase are a main feature of the mixed structures. The heavily cold rolled stainless steels possessed a high tensile strength over 1.5 GPa as well as a ductility of 10%. The strength increased to 2.0 GPa by ageing. This indicates that the heavily cold rolling can produce excellent structural materials having high strength and ductility.

Buckling evaluation method of Mod. 9Cr-1Mo steel cylinder under horizontal and vertical loads, 2; Effects of cyclic loading and interactions of axial, bending, and shear buckling

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Ando, Masanori; Miyazaki, Masashi

no journal, , 

Buckling evaluation methods capable of evaluating elasto-plastic buckling under axial compression, bending, and shear loads are required for cylindrical vessels of fast reactors to cope with thinning due to increasing diameter and application to the seismic isolation design against huge seismic ground motion. In this study, in order to cnfirm the applicability of the proposal evaluation method, several buckling tests and FE analyses were carried out using the specimens made of Modified 9Cr-1Mo steel. The buckling modes and strength data in the load region where the interaction of axial compression, bending and shear buckling could occur were examined. As a result, it was confirmed that the proposal evaluation method estimated the buckling load in the tests conservatively. In addition, buckling strength evaluated by elasto-plastic buckling analysis had good accuracy compared to each test result by considering the stress-strain relationship and imperfection of test specimen.

Study on the effect of initial imperfection shape on buckling strength of cylindrical vessel under the horizontal and vertical loads

Okafuji, Takashi*; Miura, Kazuhiro*; Sago, Hiromi*; Murakami, Hisatomo*; Ando, Masanori; Miyazaki, Masashi

no journal, , 

Buckling evaluation methods capable of evaluating elasto-plastic buckling under axial compression, bending, and shear loads are required for cylindrical vessels of fast reactors to cope with thinning due to increasing diameter and application to the seismic isolation design against huge seismic ground motion. In this study, the effect of initial imperfection and stress of large vessels manufactured by welding multiple plates on the buckling load was evaluated via a series of analyses. In these analyses, the superimposition of global imperfection over the entire vessel due to accumulation of misalignment in buckling mode imperfection had minimal effect on the buckling load. Accordingly, the length for measuring the imperfection amplitude should correspond to the wavelength of the buckling mode. The local imperfection and residual stress by welding also exerted small effects on the buckling load.