2005 Fiscal Year Final Research Report Summary
Fracture Mechanism and Strength Evaluation of Functionally Graded Materials Taking Account of Inhomogeneity and Gradation of Microstructure
| Project/Area Number |
15360050
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Shizuoka University |
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Principal Investigator |
TOHGO Keiichiro Shizuoka University, Faculty of Engineering, Professor, 工学部, 教授 (10155492)
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| Co-Investigator(Kenkyū-buntansha) |
ARAKI Hiroyasu Shizuoka University, Faculty of Engineering, Research Associate, 工学部, 助手 (60115433)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Functionally graded materials / Composite materials / Inhomogeneity / Composite model / Strength evaluation / Fracture toughness test / Fracture test / Fatigue test |
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| Research Abstract |
In order to apply ceramic-metal functionally graded materials (FGMs) as heat resistive structural materials, it is important to establish evaluation method of strength taking account of inhomogeneity and gradation of microstructure in FGMs and to make clear their fracture mechanism and strength under mechanical and thermal loading. In this investigation, numerical method for FGMs and test method for small specimens at room temperature to elevated temperature were established, and fracture behavior and strength of ceramic-metal FGMs were examined. Obtained results are summarized as follows.
1.A model of two-phase composites is developed based on the micromechanics and concept of matricity for interpenetrating microstructure. By incorporating this model into a finite element method, the numerical method taking account of inhomogeneity and gradation of microstructure in FGMs is established.
2.The size of FGMs fabricated by powder metallurgy is about 30mm in diameter and 10mm in thickness. The tests method to evaluate fracture mechanism, fracture toughness and crack growth behavior by small specimens under at room temperature to elevated temperature is established.
3.Non-graded composites with deferent composition and FGMs are fabricated by powder metallurgy using partially stabilized zirconia (PSZ) and austenitic stainless steel (SUS 304). Elastic moduli, fracture strength, fracture toughness and crack growth behavior are examined for these materials at room temperature to elevated temperature and influence of inhomogeneity and gradation of microstructure is made clear.
From the above results, method to predict the fracture behavior in FGMs and method to evaluate strength of FGMs are suggested based on the micromechanics and fracture mechanics.
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