| Co-Investigator(Kenkyū-buntansha) |
TANAKA Hiroshi Kobe University, Department of Mechanical and Systems Engineering, Associate Professor, 大学院・自然科学研究科, 助教授 (80236629)
HIWA Chiaki Kobe University, Department of Mechanical and Systems Engineering, Research Associate, 大学院・自然科学研究科, 助手 (80294198)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2004: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
The purpose of the present project is to construct fatigue damage evaluation systems for design and assurance of integrity of MEMS. For this purpose, we proposed a unique method, which combined the measurement of intrusion depth by AFM and identification of the slip direction by EBSP. The value of slip distance could be evaluated by this method, and it was found to be constant for all crack initiation sites. For austenitic stainless steel, the change of magnetism by martensitic transformation in fatigue process was utilized to evaluation of fatigue damage. In this measurements, MFM and MI sensor were employed. For the measurement of size and shape of subsurface inclusions and cracks in micro-materials, X-ray computed tomography using synchrotron radiation was employed, and inclusion and cracks larger than 5μm could be detected.
Fatigue tests of Zr-based bulk metallic glass were conducted, which is most promising material for micro-machines. In contrast with most of brittle materials, the metallic glass showed fatigue behavior. The fatigue strength was much lower than the tensile strength, and it had fatigue limit. From the surface observations of the fatigued specimen, a shear band was found to be formed just before crack initiation. The fatigue crack propagation tests were also conducted. The fatigue crack propagation rate was found to be controlled by the stress intensity range, ΔK, or its effective component, ΔK_<eff>, independent of the stress ratio and the loading frequency. In aqueous environment, the fatigue crack propagation was time dependent.
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