| Project/Area Number |
13305011
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 | Nagoya University |
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Principal Investigator |
TANAKA Keisuke Nagoya Univ., Graduate School of Engng, Professor, 工学研究科, 教授 (80026244)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Kazuo Nagoya Univ., Graduate School of Engng, Professor, 工学研究科, 教授 (30262851)
SAKAIDA Yoshihisa Shizuoka Univ., School of Engng, Professor, 工学部, 助教授 (10334955)
AKINIWA Yoshiaki Nagoya Univ., Graduate School of Engng, Assoc.Professor, 工学研究科, 助教授 (00212431)
KIMURA Hidehiko Nagoya Univ., Graduate School of Engng, Research Assoc., 工学研究科, 助手 (60345923)
KIMACHI Hirohisa Meijo Univ., School of Engng Science, Lector, 理工学部, 講師 (30324453)
田中 拓 神戸大学, 工学部, 助教授 (80236629)
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| Project Period (FY) |
2001 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥50,050,000 (Direct Cost: ¥38,500,000、Indirect Cost: ¥11,550,000)
Fiscal Year 2003: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2002: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2001: ¥42,380,000 (Direct Cost: ¥32,600,000、Indirect Cost: ¥9,780,000)
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| Keywords | Fatigue / Crack / Composites / X-ray stress measurement / Fracture mechanics / Microbeamn X-rays / Fracture mechanisms / Micromechanics / 微視機構 |
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| Research Abstract |
1. A new system of microbeam stress measurement was developed by using a high intensity X-ray generator and a position sensitive detector. The stress in the area of about 100 μm was measured with a high precision by the new system. The system was also used to measure the in-plane stress in the surface region of thin films with submicrometer thickness.
2. With the use of a high intensity X-rays from a synchrotron source, SPring-8, the stresses in the near crack-tip region in steel, ceramics and composites were successfully measured and used to predict the propagation behavior of cracks.
3. Using electron back scattering pattern and atomic force microscopy, the crystallographic condition of fatigue crack initiation in fine-grained steels is proposed. In the early stage of fatigue crack propagation, the crack deflection and branching increase the resistance of crack propagation.
4. The crack deflection and branching induce the fatigue crack closure level, and the crack propagation rate was a unique function of the effective stress intensity factor range.
5. The effects of the grain boundaries and second phase on fatigue crack propagation was modeled by the blocked slip band near the crack tip. The crack closure is further included in the model. The relative role of microstructural barriers and crack closure on the threshold condition of small fatigue cracks were calarified.
6. The effect of mixed mode loading on the fatigue crack propagation behavior was studied by using a precracked hollow cylinder under mixed torsional and axial loading. The fatigue crack propagation direction is controlled by the maximum range of tangential stress near the crack tip.
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