| Project/Area Number |
09650112
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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) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1998: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1997: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | Shape memory alloy / Unified thory / Transformation condition / Thermomechanical loads / Transformation surfarce / Martensitic transformation / Back stress / Strain recovery |
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| Research Abstract |
A transformation condition, which depends on the thermodynamic generalized forces and the internal variables, was introduced to describe the start and progress of the martensitic transformation. A set of evolution equations for the internal variables were derived by solving a conditional extremum problemcomposed of the dissipation inequality and the tranformation condition. The thermoelastic, rate-type, constitutive relations and the evolution equations govren the behavior of the alloy. The transformation condition introduced was proved to be judt the transformation driving force discussed in metallurgy. The concepts of the "isotropicphardening" and the "kinematical hardening" were developed theoretically.
The martensite start condition and the austenite start/finish conditions were determined experimentally under the multiaxial stress state. The martensite start surface, represented by an oval cone, was asymmetric in the stress-temperature space, thus approving the theory with the third invariant of the stress deviator. The austenite start consition was given by a plane in the stress-temperature space. The direction of the plane depends on the martensite variants induced during loading, whereas the posion of the plane the amount ofthe martensite. The austenite start plane translates depending on the amount of martensite. In case many martensite variants are induced during loading, the austenite start condition is represented by a polygonal cone.
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