| Project/Area Number |
10650445
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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 |
土木材料・力学一般
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
IWAKUMA Tetsuo Dep. of Civil Eng., Tohoku University, Professor, 大学院・工学研究科, 教授 (60120812)
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| Co-Investigator(Kenkyū-buntansha) |
GOTO Fumihiko Dep. of Civil Eng., Tohoku University, Research Associate, 大学院・工学研究科, 助手 (10261596)
中沢 正利 東北大学, 大学院工学研究科, 助教授 (20198063)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Localization / Cyclic Loading / Elasto-Plasticity / Double-Slip / Progressive Failure / Non-Coaxiality / FEM / Stability / 繰り返し戴荷 / 微視すべり |
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| Research Abstract |
Many localized deformations are observed in the ultimate state of structural and geotechnical materials. Since it is important to predict how such localized deformations are initiated and developed, we propose a constitutive model which is represented by small number of parameters and yields no difficulty in numerical calculations. The model includes a micro-slip mechanism as the second inelastic part of deformation after the condition of localization of deformation by Hill is satisfied. The first mechanism is modeled using non-coaxiality which triggers the localization under plane strain condition. The micro-slips are formulated by the double-slip theory.
Numerical check with standard tensile tests shows stable numerical calculation up to very large deformation states. Comparison in this bench-mark tests results in good quantitative accuracy of the large deformation behavior, and in good qualitative resemblance of the distribution of localized deformation bands. Compression tests and indentation problems are solved to show eligibility of the present model. Since this model can resist in tension, the results cannot be compared directly with those of geomaterials. But the results of the progressive development of high strain distribution are very similar to those observed in large-scale tests in several laboratories.
As an application to the structural problems, a thin plate under cyclic loading is analyzed. This plate is a partial model of web plates in steel box piers under the action of a heavy earthquake. Results show that the non-coaxiality helps wide distribution of high plastic deformation within this thin plate after its buckling. Especially the bending distribution of strain become no longer linear because of high localization of plastic strains in one side of thin plates.
The model proposed an be easily enhanced for geomaterials including dilatancy and pressure sensitivity.
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