| Budget Amount *help |
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2013: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2012: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2011: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
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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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