2023 Fiscal Year Final Research Report
Research on a technique of restraining fatigue crack growth using wedge effects of corrosion products
| Project/Area Number |
20K04677
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 22020:Structure engineering and earthquake engineering-related
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| Research Institution | National Institute of Maritime, Port and Aviation Technology |
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Principal Investigator |
Takahashi Ichihiko 国立研究開発法人海上・港湾・航空技術研究所, 海上技術安全研究所, 研究員 (30425748)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 疲労き裂 / き裂進展 / くさび効果 / 腐食生成物 / 高含水ジェル / き裂進展抑制シート / 含水成分 / 流電陰極層 |
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| Outline of Final Research Achievements |
Crack growth restraining sheets with a high water content gel were manufactured by way of trial and applied to plate specimens of steel, and the efficacy of the sheets to restrain crack growth was evaluated by fatigue tests. In order to find a local humid (or wet) corrosive environment, which is most suitable for the crack growth restraint by wedge effects of corrosion products on the crack surfaces, water components absorbed in the gel and effects of a cathode layer as promoting factors of the corrosive reaction were comparatively examined. As a result, it was found that the efficacy of the gel sheets with 3% salt water and synthetic sea water was remarkable (4.1~9.6 times extension in failure life), and the cathode layer produced certain additional positive effects in those gel sheets.
Above results were reported through a research paper and a presentation, and the fundamental techniques were applied for a patent.
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| Free Research Field |
金属疲労、海洋工学
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| Academic Significance and Societal Importance of the Research Achievements |
構造物に生じる損傷のうち、金属疲労に起因するものの割合は依然として高く、発生した疲労き裂が進展し続けて重大な事故に至ることのないよう、適切な対策（補修）を施す必要がある。これまでにも、き裂内に腐食生成物が生じると、所謂くさび効果によりき裂進展速度が著しく抑制される場合のあることが報告されていたが、現場における局所的な腐食湿潤環境の実現や制御が難しいことから、実際の補修法として積極的に利用しようとする例は見当たらなかった。本研究の成果はそのような課題に応えるものであり、従来、構造物において負の因子と捉えられてきた腐食現象を、き裂進展抑制のためのプラス因子として利用したところに特徴がある。
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