2013 Fiscal Year Final Research Report
Study on evaluation method of distribution of fatigue lives of defect-sensitive materials
| Project/Area Number |
23560083
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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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| Research Field |
Materials/Mechanics of materials
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| Research Institution | University of Toyama |
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Principal Investigator |
ISHIHARA Sotomi 富山大学, 大学院理工学研究部(工学), 名誉教授 (60019221)
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| Co-Investigator(Kenkyū-buntansha) |
MASUDA Kenichi 富山大学, 大学院理工学研究部(工学), 講師 (40548153)
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| Project Period (FY) |
2011 – 2013
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| Keywords | 疲労 / 信頼性 |
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| Research Abstract |
Fatigue tests under different R ratios were conducted using an extruded Mg alloy. In order to estimate the maximum inclusion area within the dangerous section of the specimen, the extreme-value statistics proposed by Gumbel was utilized. An initial crack length can be estimated by using the distribution of the extreme-value of the inclusion areas with an assumption that inclusion is equivalent to the crack. To analyze the small fatigue crack propagation behavior, a modified linear elastic fracture mechanics parameter, M proposed by McEvily et al was used. The relationship between the crack propagation rate da/dN and M parameter was found to be appropriate in predicting the fatigue lives under different R ratios. Moreover, the distribution of fatigue lives can also be predicted with Monte-Carlo simulation using the distribution of the extreme-value distribution of the inclusion areas and M parameter. The estimated results were in good agreement with the experimental ones.
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