| Project/Area Number |
11650095
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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 | Tokyo Metropolitan Institute of Technology |
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Principal Investigator |
TANAKA Kikuaki Department of Engineering, Tokyo Metropolitan Institute of Technology, Professor, 工学部, 教授 (80081256)
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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 |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | Fe-based Shape memory alloy / Multiaxial stresses / Transformation-start condition / Transformation-start curve / Reverse transformation-start curve / Reverse transformation-start cone / 逆変態条件 / 変態面 / 応力―温度空間 / 変態錐面 / 応力第3不変量 |
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| Research Abstract |
The transformation-start and -finish conditions are identified in an Fe-based shape memory alloy by carrying out the tension/compression-torsion tests of thin-walled tubular specimens.
The martensite-start condition determined in the isothermal proporional loading is represented by the ovalshape curves on the axial stress-shear stress plane, thus being different from the von Mises yield condition in plasticity. The temperature effect is isotropic. The third invariant of the stress should, therefore, be taken into account when constructing a transformation thermomechanical theory.
The austenite-start condition (the reverse transformation-start condition) is represented by a plane in the stress-temperature space. The direction of its unit normal depends on the direction of the pre-stressing, meaning on the type of the martensite variants induced in the pre-stressing process. When several types of variants are induced during pre-stressing, a polygonal cone is formed to represent the austenite-start condition in the stress-temperature space. The position of the plane in the stress-temperature space is governed by the amount of the variants.
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