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Fatigue crack propagation under various kind of loading

Research Project

Project/Area Number 06555302
Research Category

Grant-in-Aid for Scientific Research (A)

Allocation TypeSingle-year Grants
Section試験
Research Field 船舶工学
Research InstitutionKYUSHU UNIVERSITY

Principal Investigator

TOYOSADA Masahiro  Faculty of Engineering, KYUSHU UNIVERSITY Professor, 工学部, 教授 (30188817)

Co-Investigator(Kenkyū-buntansha) ISHIKAWA Kuniteru  NKK corporation Engineering Research Center, General Manager of Ship & Marine St, エンジニアリング研究所, 構造研究室室長
NIWA Toshio  Faculty of Engineering, KYUSHU UNIVERSITY Research Associate, 工学部, 助手 (10208267)
YAMAGUCHI Kikuji  Faculty of Engineering, KYUSHU UNIVERSITY Research Associate, 工学部, 助手 (70037943)
GOTOH Koji  Faculty of Engineering, KYUSHU UNIVERSITY Assistant Professor, 工学部, 講師 (60274487)
Project Period (FY) 1994 – 1996
Project Status Completed (Fiscal Year 1996)
Budget Amount *help
¥12,800,000 (Direct Cost: ¥12,800,000)
Fiscal Year 1996: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1995: ¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 1994: ¥6,100,000 (Direct Cost: ¥6,100,000)
Keywordscrack opening and closure / random load / DELTAKAPPA_<RP> / plastic zone size received fatigue damage / inherent stress / cohesive force model / 二段二重ブロック荷重 / 過小荷重による疲労き裂の加速現象 / シミュレーションモデル / 表面き裂の合体成長 / 等価分布応力 / 遅延減速現象 / 疲労き裂の停留条件 / 表面き裂のK値 / バネモデル
Research Abstract

A Simulation model of fatigue crack opening and closing phenomena is introduced by developing Dugdale model.It is confirmed that the simulated RPG load (Re-tensile plastic zone Generated load) is in good agreement with experimental one.It becomes clear that a delayd retardation effect on fatigue crack propagation just after decreased maximum load can be also quantitatively assessed by effective stress intensity factor range DELTAKAPPA_<RP> corresponding to the period in which the re-tensile plastic zone appears, and stopping condition of a fatigue crack propagation is that DELTAKAPPA_<RP>*0.
It is also confirmed from the model that plastic zone size omega received fatigue damage is proportional to a two power of DELTAKAPPA_<RP>. It is reported that a fatigue crack propagation curve in residual stress distribution field and under "storm model" loading with changing mean load can be quantitatively assessed by using omega. However a problem occures in case of receiving very large spike load, which is assessed to unsafe side.
In the early stage of fatigue initiation, small surface cracks emanate and repeat coalescence one after another. Therefore aspect ratio of each surface crack has a large scatter. However the aspect ratio of a flctitious representative surface crack of which K value at the deepest point is the same as an increased K value due to interference effect of vicinity surface cracks and the depth is the same of the same of the deepest surface crack among surface cracks changes to be linear to the depth before the completion of coalesence. Moreover the method of a surface crack to be modeled into two dimensional problem by series springs model is also introduced.

Report

(4 results)
  • 1996 Annual Research Report   Final Research Report Summary
  • 1995 Annual Research Report
  • 1994 Annual Research Report
  • Research Products

    (21 results)

All Other

All Publications (21 results)

  • [Publications] 豊貞雅宏・丹羽敏男: "RPG荷重のシミュレーション" 日本造船学会論文集. 176. 427-438 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 豊貞雅宏・丹羽敏男・山口喜久次: "長いき裂に対する疲労き裂遅延減速現象とき裂停留条件について" 日本造船学会論文集. 176. 439-446 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 豊貞雅宏・丹羽敏男: "残留応力場における疲労き裂伝播挙動" 日本造船学会論文集. 178. 505-511 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 豊貞雅宏・丹羽敏男・後藤浩二・江藤健一他: "二次元化による表面き裂のK値近似解法" 日本造船学会論文集. 178. 535-543 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 豊貞雅宏・山口喜久次・武田謙二郎・竹下直宏: "切欠底に生じる疲労表面き裂のアスペクト比変化についての実験的検討" 西部造船会会報. 91. 169-176 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 豊貞雅宏 他3名: "ΔK_<RP>の物理的意味と構造物の疲労寿命推定法" 日本造船学会論文集. 180. 747-539 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 豊貞雅宏 他2名: "Physical meaning of ΔK_<RP> and fatigue crack propagation in the residual stress distribution fleld" International Jouranl of Fatigue. (掲載決定).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Masahiro Toyosada and Toshio Niwa: "Simulation of RPG load" Jour.of the Soc.of Naval Architects of Japan. Vol.176. 427-438 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Masahiro Toyosada, Toshio Niwa and Kikuji Yamaguchi: "Phenomena of Delayd Reterdation and Crack Stopping Condition for a Long Fatigue Crack" Jour.of the Soc.of Naval Architects of Japan. Vol.176. 439-446 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Masahiro Toyosada and Toshio Niwa: "Fatigue Crack Propagation Behaviro in the Field of Residual Stress Distribution" Jour.of the Soc.of Naval Architects of Japan. Vol.178. 505-511 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Masahiro Toyosada Toshio Niwa koji Gotoh: "Approximate Solution of K Value for a Surface Crack due to two Dimensional Problem by Series Springs Model" Jour.of the Soc.of Naval Architects of Japan. Vol.178. 535-543 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Masahiro Toyosada Kikuji Yamaguchi, Kenjiro Takeda and Naohiro Takeshita: "Experimental Study on the Change of Aspect Ratios of Surface Cracks Emanated from Notch Root" The West-Japan Society of Naval Architects. No.91. 169-176 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Masahiro Toyosada et.al.: "Physical meaning of DELTAKAPPA_<RP> and assessment of fatigue crack propagation life for structures" Jour.of the Soc.of Naval Architects of Japan. Vol.180. 539-547 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Masahiro Toyosada et.al.: "Phhsical meaning of DELTAKAPPA_<RP> and fatigue crack propagation in the residual stress distribution field" International Journal of Fatigue. (in publishing).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 豊貞 雅宏 他3名: "ΔK_<RP>の物理的意味と構造物の疲労寿命推定法" 日本造船学会論文集. 第180号. 539-547 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] 豊貞 雅宏 他2名: "Physical meaning of ΔK_<RP> and fatigue crack propagation in the residual stress distribution fild" International Journal of Fatigue. (掲載決定).

    • Related Report
      1996 Annual Research Report
  • [Publications] 豊貞雅宏 丹羽敏男: "残留応力場における疲労き裂伝播挙動" 日本造船学会論文集. 178. 505-511 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] 豊貞雅宏・丹羽敏男・後藤浩二・江藤健一 他: "二次元化による表面き裂のK値近似解法" 日本造船学会論文集. 178. 535-543 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] 豊貞雅宏・山口喜久次・武田謙二郎・竹下直宏: "切欠底に生じる疲労表面き裂のアスペクト比変化についての実験的検討" 西部造船会会報. 91. 169-176 (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] 豊貞雅宏・丹羽敏男: "RPG荷重のシミュレーション" 日本造船学会論文集. 176. 427-438 (1994)

    • Related Report
      1994 Annual Research Report
  • [Publications] 豊貞雅宏・丹羽敏男・山口喜久次: "長いき裂に対する疲労き裂遅延減速現象とき裂停留条件について" 日本造船学会論文集. 176. 439-446 (1994)

    • Related Report
      1994 Annual Research Report

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Published: 1994-04-01   Modified: 2016-04-21  

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