1994 Fiscal Year Final Research Report Summary
Crack Propagation in a First Way by Cyclic High Hrat Flux
| Project/Area Number |
05680428
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Nuclear fusion studies
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| Research Institution | University of Tsukuba |
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Principal Investigator |
SAITO Masakatsu Univ.of Tsukuba, Inst.of Engng Mech, Professor, 構造工学系, 教授 (70029198)
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| Project Period (FY) |
1993 – 1994
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| Keywords | fusion reactor / first wall / crack growth / high heat flux |
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| Research Abstract |
A 3 mm thick plate with a precrack is taken as a simple model of the first wall of the nuclear fusion reactor. To simulate the crack growth, high heat flux of 3MW/m2 is radiated to a circular area of 12 mm in diameter. Electron Beam is used as a heat source. 0.5 sec irradiation and 29.5 sec cooling is one cycle. The crack growth DELTAa is measured with respect to the cyclic number of heat irradiation. Average tensile stress of 50Mpa, 100MPa and 150MPa are loaded to the specimen in order to clarify the effects of the boundary condition. Finite element code ABAQUS is used for transient heat coduction analysis and elastoplastic stree analisys. The nonlinear fracture mechanics parameter J is numerically evaluated. Thus we have DELTAa/DELTAN (N : cyclic number) -DELTAJ relation.
In case of the average stress of 0MPa, (which is a result of the last year) 50MPa and 100MPa, the crack tip is yielded in compression by heat irradiation and is yieled in tesion by cooling. The rapid change of stress at crack tip make the crack to grow. This behavior is estimated by the above numrical model. But in case of the average stress 150MPa, the yield in compression does not appear by heat irradiation. The crack propagation behavior is similar to the conventional high temperature fatige test. This means that another model for culculation is needed to estimate the crack growth in the high average stress range.
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