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2001 Fiscal Year Final Research Report Summary

Evaluation and modeling of fracture toughness based on the mezzo-scopic elastic-plastic fracture mechanics

Research Project

Project/Area Number 11450262
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Structural/Functional materials
Research InstitutionNAGOYA UNIVERSITY

Principal Investigator

MIYATA Takashi  Nagoya University, Materials Sci. & Eng., Prof., 工学研究科, 教授 (20023228)

Co-Investigator(Kenkyū-buntansha) ABE Eiji  Nagoya University, Materials Sci. & Eng., Assit. Prof., 工学研究科, 助手 (80303676)
TAGAWA Tetsuya  Nagoya University, Materials Sci. & Eng., Asoc. Prof., 工学研究科, 助教授 (00216805)
Project Period (FY) 1999 – 2001
KeywordsFracture toughness / Elastic-plastic fracture mechanics / Local approach / The Weibull fracture stress / Steels / Toughness testing
Research Abstract

Cleavage fracture toughness of steels was mezzo-scopically analyzed on the basis of the statistical local fracture criterion approach. The statistical Weibull stress criterion at the crack tip region suggests that the cleavage fracture toughness of steels can be described as a function of the yield stress, and other mechanical properties of the materials. Formulation of the cleavage fracture toughness was first examined through an investigation on correlation between the cleavage fracture toughness and the cleavage fracture stress obtained in notched round bar specimens in accordance with the theoretical prediction. Then, scatter of the toughness, strain rate and specimen thickness effect on the toughness, deterioration of the toughness due to cold working and irradiation, and improvement of the toughness caused by the Ni addition, were analyzed through the formulation above.
The specimen size requirements in toughness qualification are also discussed on the basis of statistical local fracture criterion approach. The Weibull stress criterion for cleavage fracture is applied to the constraint loss field at the crack tip described with the toughness scaling model (TSM). The new model proposed demon strates that the TSM is a particular case for a material with a particular combination of the Weibull shape parameter, m and the strain hardening exponent, n. Analytical prediction indicates that the specimen size re quirements in toughness must be significantly depending on the value of n and m of the material. The 2-and 3- dimensional FE analysis were performed to confirm above analytical prediction.

  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] 田川, 哲哉: "破壊靭性試験における試験片寸法の標準化に関する一考策"日本造船学会論文集. 186. 485-497 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miyata, Takashi: "A Proposal for Specimen Size Requirements in Toughness Qualification with the Weibull Stress Criterion"Jour. Testing & Evaluation. 28. 62-65 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miyata, Takashi: "Mezzo-scopic Analysis of Fracture Toughness in Steels"Proceedings of SAM 2000 IV Latin American Colloquium on Fracture and Fatigue. (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miyata, Takashi: "Application of Local Approach to Dynamic Fracture Toughness of Steels"Proceedings of Charpy Centenary Conference 2001. Volume 2. 761-768 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miyata, Takashi: "Qualification of Cleavage Fracture Toughness on the Basis of Local Fracture Criterion Approach"Advances in Fracture Reserch ; Proceedings of 10th International Conference on Fracture. 10th. 2.9.2 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] TAGAWA, Tetsuya: "Specimen Size Requirements for Cleavage Fracture Toughness based on the Weibull Stress Criterion"Journal of the Society of Naval Archtects of Japan. Vol. 186. 485-497 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] MIYATA, Takashi: "A Proposal for Specimen Size Requirements in Toughness Qualification with the Weibull Stress Criterion"Journal of Testing and Evaluation. Vol. 28. 62-65 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] MIYATA, Takashi: "Mezzo-scopic Analysis of Fracture Toughness in Steels"Proceedings of SAM 2000 IV Latin America Colloquim on Fracture and Fatigue. (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] MIYATA. Takashi: "Application of Local Approach to Dynamic Fracture Toughness od Steels"Proceedings of Charpy Centenary Conference 2001. Vol/2. 761-768 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] MIYATA, Takashi: "Qualification of Cleavage Fracture Toughness on the basis of Local Fracture Criterion Approach"Advances in Fracture Research; Proceedings of 10th International Conference on Fracture. paper#2.9.2. (2001)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2003-09-17  

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