1999 Fiscal Year Final Research Report Summary
Identification of plastic behaviors of structural steels at very large deformation
| Project/Area Number |
10650461
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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 |
構造工学・地震工学
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| Research Institution | NAGOYA INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
OBATA Makoto NAGOYA INSTITUTE OF TECHNOLOGY, DEPARTMENT OF CIVIL ENGINEERING, ASSOCIATE PROFESSOR, 工学部, 助教授 (30194624)
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| Project Period (FY) |
1998 – 1999
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| Keywords | plasticity / constitutive relation / plastic rupture / inverse analysis / large deformation analysis / material tests |
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| Research Abstract |
The initiation of brittle cracks in members degrades the ductility of steel structures. As observed in the Hyogoken Nanbu Earthquake, such brittle fracture is often triggered by preceding ductile fracture. The estimation of ultimate behaviors and deformation capacity of steel structures, therefore, critically depends on the ductile fracture of its members. However, few numerical method to investigate the ductile fracture of members is available because of the lack of the understandings of the quantitative aspects of such material characteristics. we have proposed an alternative experimental method to circumvent the difficulty using an FEM-based inverse analysis. This method provides a consistent way to determine the material constants by a simple uniaxial test. In the present work, we show that the FEM analysis with Gurson's model could be a suitable tool for the estimation of ductility limit of steel members. Once the material parameters are properly determined, the initiation of plastic rupture can be predicted with reasonable accuracy in terms of void volume fraction. However, we also note that the experimental result suggests the needs for the further investigation in some cases. In view of practical importance, we proposed a simple extension of Gurson's model to so called a kinematic hardening model. The modified model is coded as a plug-in user subroutine of an FEM program DIANA for practical numerical analysis.
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