• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to previous page

Observations of subcritical crack initiation and growth processes by scanning acoustic microscope

Research Project

Project/Area Number 63550085
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 材料力学
Research InstitutionOsaka University

Principal Investigator

OGURA Keiji  Osaka University, Engineering Science, Professor, 基礎工学部, 教授 (70029007)

Co-Investigator(Kenkyū-buntansha) SAKAGAMI Takahide  Osaka University, Engineering Science, Research Associate, 基礎工学部, 助手 (50192589)
NISHIKAWA Izuru  Osaka University, Engineering Science, Research Associate, 基礎工学部, 助手 (90189267)
MIYOSHI Yoshio  Osaka University, Engineering Science, Associate Professor, 基礎工学部, 助教授 (40029434)
Project Period (FY) 1988 – 1989
Project Status Completed (Fiscal Year 1989)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1988: ¥1,400,000 (Direct Cost: ¥1,400,000)
KeywordsScanning Acoustic Microscope / Fatigue / Slip bands / Surface cracks / Initial stage of crack growth / 初期き裂進展
Research Abstract

Scanning acoustic microscope (SAM) was used to investigate the the crack initiation and propagation processes in the subcritical crack growth problems such as fatigue, stress corrosion and creep. The main interest was put on examining when and how the slip bands grow into the microcracks in fatigue. The materials selected in this study were pure copper, pure nickel and type 304 stainless steel. Fatigue tests were conducted and interrupted in a certain stage. The samples were provided for the observations by SAM and an optical microscope. The results are summarized as follows.
1. The fine fatigue slip bands were able to observe when a frequency of ultrasonics was selected beyond 600MHz in the SAM observation. Subsurface informations, on the other hand, were able to obtain only when the lower frequency less than 40OMHz was used in the observations. The slip bands and cracks in the SAM image were visible best in intensity in the pure nickel samples.
2. A clear difference was often observed in the SAM images in the certain two slip bands in which no differences were found in the optical microscopic images. This was found to be due to the differences in the subsurface situation and in the surface topography of the two slip bands.
3. An interference fringes were observed around the initiated cracks, These fringes, however, were not observed for any slip bands. The transitional process from a slip band to a crack was unfortunately not examined in this study.
4. The depth and the inclined angle of the initiated cracks were estimated quantitatively by the analyses of a V(z) curve and an interference fringe.

Report

(3 results)
  • 1989 Annual Research Report   Final Research Report Summary
  • 1988 Annual Research Report
  • Research Products

    (15 results)

All Other

All Publications (15 results)

  • [Publications] 小倉敬二: "疲労き裂発生過程の超音波顕微鏡観察とその画像情報の検討" 日本機械学会関西支部論文集. No.904-1. 72-73 (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] 小倉敬二: "レ-ザ干渉法による中高温下疲労き裂開閉口の計測とき裂進展下限界" 日本機械学会論文集. 56. (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] 小倉敬二: "中高温下不活性ガス環境下における疲労き裂進展とき裂開閉口" 材料. 38. 1395-1401 (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Keiji Ogura: "Observations of fatigue crack initiation process by SAM with discussions on its image intensity" Preprint of the JSME meeting. No.904-1. 72-73 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Keiji Ogura: "Crack closure measurement at elevated temperatures using laser interferometric gage and fatigue threshold, Transactions of JSMS, 56(1990)"

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Keiji Ogura: "Fatigue threshold and crack closure in inert gas at moderately elevated temperatures, Journals of the Japan Society of Materials Science, Japan, 38(1989), pp.1395-1401."

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] 小倉敬二: "疲労き裂発生過程の超音波顕微鏡観察とその画像情報の検討" 日本機械学会関西支部論文集. No.904ー1. 72-73 (1990)

    • Related Report
      1989 Annual Research Report
  • [Publications] 小倉敬二: "レ-ザ干渉法による中高温下疲労き裂開閉口の計測とき裂進展下限界" 日本機械学会論文集. 56. (1990)

    • Related Report
      1989 Annual Research Report
  • [Publications] 小倉敬二: "中高温下不活性ガス環境下における疲労き裂進展とき裂開閉口" 材料. 38. 1395-1401 (1989)

    • Related Report
      1989 Annual Research Report
  • [Publications] 小倉敬二: 材料. 37. 1077-1083 (1988)

    • Related Report
      1988 Annual Research Report
  • [Publications] 小倉敬二: JSME International Journal.Series 1. 31. 92-99 (1988)

    • Related Report
      1988 Annual Research Report
  • [Publications] 小倉敬二: Proc of the VI Int.Congr.on Experimentel Mechanics. 2. 1267-1273 (1988)

    • Related Report
      1988 Annual Research Report
  • [Publications] 小倉敬二: 材料. 38. (1989)

    • Related Report
      1988 Annual Research Report
  • [Publications] 小倉敬二: 材料. 38. (1989)

    • Related Report
      1988 Annual Research Report
  • [Publications] 三好良夫: 日本材料学会第25回X線材料強度に関するシンポジウム講演論文集. 194-198 (1988)

    • Related Report
      1988 Annual Research Report

URL: 

Published: 1988-04-01   Modified: 2016-04-21  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi