| Project/Area Number |
06555030
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Kyushu Institute of Technology |
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Principal Investigator |
HARADA Shoji Kyushu Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (80029199)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUSHIMA Yoshihiro Kyushu Institute of Technology, Faculty of Engineering, Research Assistant, 工学部, 助手 (40156774)
KUROSHIMA Yoshihito Kyushu Institute of Technology, Faculty of Engineering, Associate Professor, 工学部, 助教授 (50253547)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 1995: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1994: ¥6,300,000 (Direct Cost: ¥6,300,000)
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| Keywords | Random Loading / Fatigue Life / Small Crack Growth / Crack Tip Opening Displacement / Rain Flow Method / ランダム疲労 / 変動応力 / 過小応力 / き裂伝ぱ / き裂開閉口 / 疲労寿命予測 |
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| Research Abstract |
To establish highly reliable fatigue life prediction method under random loading the rain flow method(RFM), originally developed as one of the most useful fatigue damage counting method, was re-interpreted by taking into account the actual fatigue process of crack initiation and propagation. Incounting fatigue damage, either cyclic plastic strain(LCF)or cyclic stress amplitude(HCF)has been used so far. Through the fatigue tests in wide fatigue region, CTOD was found to be a most suitable parameter in estimating fatigue damage. In case of LCF loading, the relationship between CTOD and the small crack growth rate corresponds fairly well to the relationship between the equivalent plastic strain and the small crack growth rate. On the other hand, the presence of the crack closure effect in HCF loading resulted in losing one-to-one correspondence found in LCF loading. This means, the crack growth rate should be estimated by using parameters DELTACTOD and DELTAKeff.
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