Refine your search:     
Report No.
 - 
Search Results: Records 1-12 displayed on this page of 12
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Effect of ratchet strain on fatigue and creep-fatigue strength of Mod.9Cr-1Mo steel

Ando, Masanori; Isobe, Nobuhiro*; Kikuchi, Koichi*; Enuma, Yasuhiro*

Nuclear Engineering and Design, 247, p.66 - 75, 2012/06

 Times Cited Count:7 Percentile:48.53(Nuclear Science & Technology)

The effect of ratcheting deformation on fatigue and creep-fatigue life in Mod.9Cr-1Mo steel was investigated. Uniaxial fatigue and creep-fatigue testing with superimposed strain were performed to evaluate the effect of ratcheting deformation on the failure cycle. In the fatigue tests with superimposed strain at 550$$^{circ}$$C, slight reductions of failure lives were observed. All of the numbers of cycles to failure in the fatigue tests with superimposed strain were within a factor of 1.5 of that of the fatigue test without superimposed strain at 550$$^{circ}$$C. The apparent relationship between failure cycles and testing parameters was not observed. It was assumed that suppression of mean stress generation by cyclic softening reduces the effect of ratcheting strain. In the creep-fatigue tests with superimposed strain, test results indicated that the accumulated stain was negligible.

Journal Articles

Effect of pre-strain and ratcheting strain on fatigue and creep-fatigue lives in Mod.9Cr-1Mo steel

Ando, Masanori; Isobe, Nobuhiro*; Date, Shingo*; Kikuchi, Koichi*; Enuma, Yasuhiro*

Zairyo, 61(4), p.377 - 384, 2012/04

The effect of ratcheting deformation and pre-strain on fatigue and creep-fatigue life in Mod.9Cr-1Mo steel was investigated. Uni-axial fatigue and creep-fatigue tests with pre-strain and progressive strain were performed to evaluate the effect of pre-strain and ratcheting strain on the failure cycle. In the fatigue tests with pre-strain, failure lives were not declined. In the fatigue tests with progressive strain, slight reductions of failure lives were observed, however, they were within a factor of 1.5 of the failure life in normal fatigue test. In the creep-fatigue tests with progressive strain, the same conclusion of the fatigue tests was obtained. In both kinds of tests, maximum mean stresses during the tests were insignificant and/or generated in early cycle in the tests, and this character is considered as a reason of that the effect of ratcheting deformation on the fatigue and creep-fatigue lives are insignificant.

Journal Articles

Experimental investigation of strain concentration evaluation based on the stress redistribution locus method

Isobe, Nobuhiro*; Kawasaki, Nobuchika; Ando, Masanori; Sukekawa, Masayuki*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 11 Pages, 2012/00

Evaluation of local strain at structural discontinuities is an important technology in high temperature design of fast reactors because the failure mode in high temperature fatigue or creep fatigue damage is usually crack initiation and growth from such a locally high strained area. A rationalized strain concentration evaluation method was discussed experimentally in this study. The stress redistribution locus (SRL) method had been proposed to improve the accuracy of local stress and strain evaluation for structural discontinuities. High temperature fatigue tests of circumferentially notched specimens were conducted accompanying with local strain measurement by a capacitance type strain gage. Measured strain was compared with the prediction by the SRL method and the applicability of the method is discussed.

Journal Articles

Experimental investigation of strain concentration evaluation based on the stress redistribution locus method

Isobe, Nobuhiro*; Kawasaki, Nobuchika; Ando, Masanori; Sukekawa, Masayuki*

Journal of Nuclear Science and Technology, 48(4), p.567 - 574, 2011/04

A rationalized strain concentration evaluation method was discussed experimentally in this study. High temperature fatigue tests of circumferentially notched specimens were conducted accompanying with local strain measurement by a capacitance type strain gage. Measured strain was compared with the prediction by the SRL method and the applicability of the method is discussed. The SRL method improves the accuracy of inelastic strain estimation with keeping conservativeness in comparison with the Neuber's rule which is used in high temperature design codes.

Journal Articles

Ratcheting deformation effect on fatigue and creep-fatigue life in Mod.9Cr-1Mo steel

Ando, Masanori; Isobe, Nobuhiro*; Date, Shingo*; Kikuchi, Koichi*; Enuma, Yasuhiro*

Dai-48-Kai Koon Kyodo Shimpojiumu Maezurishu, p.110 - 114, 2010/12

no abstracts in English

Journal Articles

Development of elevated temperature structural design method for fast reactor vessels, 3; Critical temperature difference of 316FR steel and Inconel-718 for high-cycle thermal fatigue

Okajima, Satoshi; Isobe, Nobuhiro*; Kawasaki, Nobuchika; Sukekawa, Masayuki*

Nihon Kikai Gakkai 2009-Nendo Nenji Taikai Koen Rombunshu, Vol.1, p.125 - 126, 2009/09

no abstracts in English

Journal Articles

Development of elevated temperature structural design method for fast reactor vessels, 4; Effect of ratcheting strain on 316FR creep-fatigue strength

Kawasaki, Nobuchika; Date, Shingo*; Kikuchi, Koichi*; Isobe, Nobuhiro*; Kasahara, Naoto

Nihon Kikai Gakkai M&M 2009 Zairyo Rikigaku Kanfarensu Koen Rombunshu (CD-ROM), p.535 - 536, 2009/07

The effect of ratcheting strain on creep-fatigue strength was investigated in order to adjust the strain limit. Ratcheting creep-fatigue tests were conducted at 600 $$^{circ}$$C with 1 hr hold time. Creep fatigue lives did not decrease when the accumulated strain was superimposed within 5%. Therefore the effect of ratcheting on creep-fatigue strength is negligible when accumulated strain exceeds 2%.

Journal Articles

Development of elevated temperature structural design method for fast reactor vessels, 5; Effect of ratcheting strain on 316FR fatigue strength

Okajima, Satoshi; Date, Shingo*; Kawasaki, Nobuchika; Kikuchi, Koichi*; Isobe, Nobuhiro*; Kasahara, Naoto

Nihon Kikai Gakkai M&M 2009 Zairyo Rikigaku Kanfarensu Koen Rombunshu (CD-ROM), p.537 - 538, 2009/07

no abstracts in English

Journal Articles

A Comparative study of negligible creep curves for rational elevated temperature design

Ando, Masanori; Isobe, Nobuhiro*; Kawasaki, Nobuchika; Sukekawa, Masayuki*; Kasahara, Naoto*

Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 10 Pages, 2009/07

Journal Articles

Clarification of strain limits considering the ratcheting fatigue strength of 316FR steel

Isobe, Nobuhiro*; Sukekawa, Masayuki*; Nakayama, Yasunari*; Date, Shingo*; Otani, Tomomi*; Takahashi, Yukio*; Kasahara, Naoto; Shibamoto, Hiroshi*; Nagashima, Hideaki*; Inoue, Kazuhiko*

Nuclear Engineering and Design, 238(2), p.347 - 352, 2008/02

 Times Cited Count:21 Percentile:78.91(Nuclear Science & Technology)

The effect of ratcheting on fatigue strength was investigated in order to rationalize the strain limit as a design criterion of commercialized fast reactor systems. Ratcheting fatigue tests were conducted at 550$$^{circ}$$C. Duration of the ratchet straining was set for a certain number of strain cycles taking the loading condition of fast reactors into account, and the number of cycles for strain accumulation was defined as the ratchet-expired cycle. Fatigue lives decrease as the accumulated strain by ratcheting increases. Fatigue life reduction was negligible when the maximum mean stress was less than 25 MPa, corresponding to an accumulated strain of 2.2 percent. Accumulated strain is limited to 2 percent in the present design guidelines and this strain limit is considered effective to avoid reducing fatigue life by ratcheting. Micro-crack growth behaviors were also investigated in these tests in order to discuss the life reduction mechanisms in ratcheting conditions.

Journal Articles

A Rational identification of creep design area using negligible creep curve

Sukekawa, Masayuki*; Isobe, Nobuhiro*; Shibamoto, Hiroshi; Tanaka, Yoshihiko*; Kasahara, Naoto

Proceedings of 2006 ASME Pressure Vessels and Piping Division Conference (PVP 2006)/International Council on Pressure Vessel Technology (ICPVT-11) (CD-ROM), 5 Pages, 2006/00

For expansion of non-creep design area and simplification of design procedures, a rational identification method of creep design area by negligible creep (NC) curves was studied. NC curves of six kinds of stainless and ferrite steels for fast reactors were determined at 1.5Sm (Sm: design stress intensity). These NC curves are based on domestic material data. NC curves provide the relation between temperature and time that does not induce meaningful creep strain under the constant primary stress. As for 316FR steel, which is used for reactor vessel in Japanese fast reactor, non-creep design area is identified with comparing the highest temperature and 425C (constant upper limit for austenite stainless steal) by existing Japanese Guides. However, this temperature limit can be enhanced by NC curve concept when operating (thermal transient) time is long. NC curves under higher primary stress, and the curves under secondary stress were also studied. However, at the present stage, NC curves for stress level 1.5Sm were adopted to identify creep design area. The concept of NC curve was introduced into the interim FDS (fast reactor design standard for commercialized fast reactors in Japan) to simplify the creep design of fast reactor systems. Utilizing these curves, design becomes easier for components which are employed at comparatively lower temperature under normal condition and short holding time at high temperature.

Oral presentation

Development of high chromium steel for SFR in Japan and creep-fatigue assessment of the welded joint

Wakai, Takashi; Isobe, Nobuhiro*; Date, Shingo*; Asayama, Tai; Kubo, Shigenobu*

no journal, , 

12 (Records 1-12 displayed on this page)
  • 1