| Project/Area Number |
11650102
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Hosei University |
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Principal Investigator |
SAKINO Kiyotaka Hosei University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (20120818)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
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| Keywords | High Speed Deformation / Steel Iron / Strain Rate Dependency / Hopkinson Bar Method / Thermally Activated Process / 鉄の活性化エネルギー |
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| Research Abstract |
Strain rate sensitivity of a flow stress in BCC metals is known to increase greatly in the high strain rate ranges above about 1×10^3/s. High strain rate tests are performed for low carbon iron using a modified Hopkinson pressure bar system in a strain rate range mainly from about 4×10^3 to 5×10^4/sec. At first, in order to evaluate the effects of the instantaneous strain rate and strain rate history on the dynamic flow stress of the iron at very high strain rates, the strain rate change tests are made in the strain rate range from about 10000 to 20000/sec. The results indicate that the instantaneous strain rate plays a dominant role. Furthermore, to evaluate the strain rate dependency of the dynamic flow stress at high strain rates, the stress-strain rate curve using activation energy E(τ) for deformation of pure iron obtained by Aono et al. is used. The flow stress at quasi-static strain rate region is controlled by the mechanism of a thermal activation of dislocations over short range barriers. The flow stress at strain rates ranging from about 1/sec to 2×10^4/sec is controlled by the thermally activated process of formation of kink pairs, however at higher strain rates a second rate controlling mechanism appears to be predominant.
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