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Evolution rules of a representative surface crack intiating in stress concentration regions

Research Project

Project/Area Number 16360440
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Naval and maritime engineering
Research InstitutionKYUSHU UNIVERCITY

Principal Investigator

TOYOSADA Masahiro  Kyushu University, Faculty of Engineering, Professor, 工学研究院, 教授 (30188817)

Co-Investigator(Kenkyū-buntansha) YOSHIKAWA Takao  Kyushu University, Faculty of Engineering, Professor, 工学研究院, 教授 (50380572)
GOTOH Koji  Kyushu University, Faculty of Engineering, Associate Professor, 工学研究院, 助教授 (60274487)
TSUTSUMI Seiichiro  Kyushu University, Faculty of Engineering, Research Associate, 工学研究院, 助手 (70344702)
Project Period (FY) 2004 – 2006
Project Status Completed (Fiscal Year 2006)
Budget Amount *help
¥14,900,000 (Direct Cost: ¥14,900,000)
Fiscal Year 2006: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2005: ¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 2004: ¥5,600,000 (Direct Cost: ¥5,600,000)
KeywordsFatigue / Surface crack / Change of aspect ratio of a surface crak / Hull structural elements / Material softening / 下負荷面モデル / ビーチマーク / 応力比 / 大型溶接構造物 / 材料軟化
Research Abstract

In order to evaluate the surface fatigue crack growth in stress concentration regions, authors defined the representative surface crack that enables to consider the existence of multiple surface cracks in the regions. Evolution rules of a representative surface crack and single surface crack under complex stress concentration regions investigated. Besides, the effect of material softening phenomena for fatigue crack initiation is also investigated. General aspects of the result of this project are listed below.
(1)Numerical data to give a representative surface crack are obtained by finite element analysis and the survey of literatures.
(2)It is confirmed by the measurements in fatigue test that evolution history of a representative surface crack is not affected by stress ratio.
(3)The shape of test piece in order to investigate the evolution history of fatigue surface crack under bi-axial stress gradient fields is fixed by the questionnaires about fatigue damages in hull structures, and the specimens are fabricated.
(4)Fatigue tests are performed by applying test pieces mentioned above.
(5)By referring above mentioned fatigue tests and developed theories in this research, evolution rules of a representative surface crack is updated. Simple and useful formula to estimate the aspect ratio of a representative surface crack is introduced.
(6)Elastic-Plastic finite element analyses with subsurface model as a constitutive equation of material are performed in order to investigate the effect of material softening phenomena for fatigue crack initiation. As a result of above mentioned analyses and experiments, it is confirmed plastic strain enables to accumulate if applied stress is lower than yield stress and upper than proportional ratio.

Report

(4 results)
  • 2006 Annual Research Report   Final Research Report Summary
  • 2005 Annual Research Report
  • 2004 Annual Research Report
  • Research Products

    (10 results)

All 2006

All Journal Article (10 results)

  • [Journal Article] 応力集中部から発生する複数疲労表面き裂の成長評価法に関する研究2006

    • Author(s)
      穴井陽祐, 村上幸治, 後藤浩二, 豊貞雅宏
    • Journal Title

      日本船舶海洋工学会講演論文集 第3号

      Pages: 383-386

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Annual Research Report 2006 Final Research Report Summary
  • [Journal Article] 等価分布応力概念と仮想単独表面き裂について2006

    • Author(s)
      豊貞雅宏, 後藤浩二
    • Journal Title

      日本機械学会2006年度年次大会講演論文集 Vol.1

      Pages: 663-664

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Annual Research Report 2006 Final Research Report Summary
  • [Journal Article] 下負荷面の概念を導入した弾塑性モデルによる繰返し変形解析2006

    • Author(s)
      堤成一郎, 村上幸治, 徳田千晶, 中山祐一, 矢嶋泰基, 豊貞雅宏
    • Journal Title

      日本機械学会2006年度年次大会講演論文集 Vol.1

      Pages: 773-774

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Annual Research Report 2006 Final Research Report Summary
  • [Journal Article] 繰返し荷重に伴う塑性域の成長について2006

    • Author(s)
      堤成一郎, 豊貞雅宏
    • Journal Title

      日本機械学会2006年度年次大会講演論文集 Vol.1

      Pages: 667-668

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Annual Research Report 2006 Final Research Report Summary
  • [Journal Article] 弾性境界面およびダメージを考慮した繰返し弾塑性モデル2006

    • Author(s)
      堤成一郎, 豊貞雅宏
    • Journal Title

      日本機械学会2006年度年次大会講演論文集 Vol.1

      Pages: 771-772

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Annual Research Report 2006 Final Research Report Summary
  • [Journal Article] A conventional growth estimation method of multiple surface cracks Generated by fatigue in the concentration region2006

    • Author(s)
      Anai, Y., Murakami, K.Gotoh, K., Toyosada, M.
    • Journal Title

      Conference Proceedings of the Japan Society of Naval Architects and Ocean Engineers Vol.3

      Pages: 383-396

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Concepts of Equivalent Distributed Stress and Representative Surface Crack in FLARP2006

    • Author(s)
      Toyosada, M., Gotoh, K.
    • Journal Title

      Proceedings of Mechanical Engineering Congress 2006 Japan Vol.1

      Pages: 663-664

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Plastic Deformation under Cyclic Loading Condition2006

    • Author(s)
      Tsutsumi, S., Toyosada, M.
    • Journal Title

      Proceedings of Mechanical Engineering Congress 2006 Japan Vol.1

      Pages: 667-668

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Cyclic Plasticity model incorporation elastic boundary and damage concept2006

    • Author(s)
      Tsutsumi, S., Toyosada, M.
    • Journal Title

      Proceedings of Mechanical Engineering Congress 2006 Japan Vol.1

      Pages: 771-772

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Cyclic deformation of metal predicted by elastoplastic constitutive model with subloading surface concept2006

    • Author(s)
      Tsutsumi, S., Murakam, K., Tokuda, C., Nakayama, Y., Yajima, D., Toyosada, M.
    • Journal Title

      Proceedings of Mechanical Engineering Congress 2006 Japan Vol.1

      Pages: 773-774

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary

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Published: 2004-04-01   Modified: 2016-04-21  

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