| Project/Area Number |
60460084
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
材料力学
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| Research Institution | Ritsumeikan University |
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Principal Investigator |
OHNAMI Masateru Faculty of Science and Engineering, Ritsumeikan University, 理工学部, 教授 (60066587)
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| Co-Investigator(Kenkyū-buntansha) |
SAKANE Masao Faculty of Science and Engineering, Ritsumeikan University, 理工学部, 助手 (20111130)
元家 勝彦 広島電機大学, 教授 (10069198)
MOTOIE Katsuhiko Hiroshima-Denki Institute of Technology
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥6,500,000 (Direct Cost: ¥6,500,000)
Fiscal Year 1986: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1985: ¥5,500,000 (Direct Cost: ¥5,500,000)
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| Keywords | High Temperature / Low Cycle Fatigue / Biaxial Stress / Constitutive Relation / Dislocation / X-ray Diffraction / 非比例負荷 |
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| Research Abstract |
Cyclic biaxial constitute relation was determined for an austenitic stainless steel SUS 304 and 1Cr-1Mo-1/4V aged and non-aged steels in the three test methods under combined push-pull and reversed torsion load at 823 K. The three test methods were the companion method, incremental/decremental method (I/D method) and step-up method. For 1Cr-1Mo-1/4V steel only the companion test was carried out. Proportional and non-proportional tests were carried out for SUS 304 steel in the I/D method. The major conclusions obtained are as follows.
1. The biaxial cyclic constitutive relation in the three test methods is well correlated by the Mises equivalent stress and stress except 1Cr-1Mo-1/jV aged steel. The scatter of the data in the companion test is comparatively large. 2. The cyclic constitutive relation in the companion test differs from that in the I/D test. The cyclic hardening exponent in the companion test is larger than that in the I/D test.
3. Larger cyclic stress amplitude is observed in the non-proportional test in comparison with the proportional test. The cause of the increase in the stress amplitude due to the non-proportional loading is discussed by TEM observations and X-ray diffraction. A simple equation to estimate the stress amplitude in the non-proportinal test is proposed. The estimated results based on the equation agree well with the experimental results.
4. FEM analysis is made for plate notched specimens using the cyclic constitutive relations obtained in the companion and the I/D tests in order to know how the difference in the constitutive relation affects the low cycle fatigue design life. The calculated results using both the constitutive relations do not differ each other, so that the difference in the constitutive relation due to the test method does not have an large effect on the design fatigue life.
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