| Project/Area Number |
08650811
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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 |
Structural/Functional materials
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KIM Byung-Nam The University of Tokyo, Research Center for Advanced Science and Tichnology, Research Associate, 先端科学技術研究センター, 助手 (50254149)
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| Co-Investigator(Kenkyū-buntansha) |
ENOKI Manabu The University of Tokyo, Research Center for Advanced Science and Technology, Re, 先端科学技術研究センター, 助教授 (70201960)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Ceramics / Crack path / Particle / Interface / Residual stress / Fracture resistance / Composites / Body force method / き裂経路 / 破壊靱性 |
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| Research Abstract |
A system simulating the crack propagation behavior in spherical particle-dispersed ceramic matrix composites was developed in order to investigate the effect of thermal residual stresses on crack path and fracture resistance. As a material, SiC particle-dispersed Al_2O_3 matrix composites and Al_2O_3 particle-dispersed SiC matrix composites were selected. The interaction of the concentrated stress field by a crack with residual stress due to the thermal expansion mismatch between particle and matrix was investigated along with the crack path. Stress intensity factors of the multiply deflected crack was numerically calculated by the body force method, and the 2-dimensional continuous crack propagation behavior was simulated in the range of the volume fraction of particles between 5 and 30%. In the SiC(p)-Al_2O_3 composites, a crack has a tendency to be attracted by the particles due to the residual tensile stress in the circumferential direction around the SiC particles, while a tendency to be pushed out due to the residual tensile stress in the radial direction around Al_2O_3 particles. The simulated fracture resistance (R-curve) in the Sic(p)-Al_2O_3 composites increases with crack growth, and the interface toughness has little effect on the R-curve. The increasing R-curve behavior was also found in the actual SiC(p)-Al_2O_3 composites made by hot-press, indicating that the R-curve behavior can be accomplished by only the residual stresses. In addition, the fracture toughness of the SiC(p)-Al_2O_3 composites increases with volume fraction of particles, while that of the Al_2O_3(p)-SiC composites decreases. These behavior is a result of the interaction between a crack and the thermal residual stresses, and is somewhat different from the results of the models of straight crack. In the latter case, 3-dimensional crack propagation is expected to be a primary toughening mechanism.
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