1995 Fiscal Year Final Research Report Summary
Fundamental Investigation on Crack Behavior in Particulate-Dispersed Functionally Graded Material
| Project/Area Number |
06650100
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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 |
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, Associate Professor, 工学部, 助教授 (10155492)
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| Co-Investigator(Kenkyū-buntansha) |
ARAKI Hiroyasu Shizuoka University, Faculty of Engineering, Research Associate, 工学部, 助手 (60115433)
ISHII Hitoshi Shizuoka University, Faculty of Engineering, Professor, 工学部, 教授 (90022235)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Functionally Graded Material / Fracture Mechanics / Crack Behavior / Particulate Reinforced Composite / Finite Element Method / Crack Tip Singular Field / Fracture Toughness / Glass Particle Reinforced Nylon 66 |
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| Research Abstract |
In this project, in order to make clear the crack behavior in a functionally graded material (FGM), analytical work on influence of gradient on the fracture mechanics parameters and crack tip singular field, and experimental work on the mechanical properties and fracture toughness in composites and FGMs were carried out. Obtained results are summarized as follows.
1. Elastic and elastic-plastic analyzes of a crack in a particulate-dispersed FGM were carried out using a newly developed finite element method based on Tohgo-Chou-Weng's constitutive relation. The following conclusions are derived : (1) The stress intensity factors of a crack in FGM is affected by the gradient of mechanical properties. (2) The elastic and plastic stress singular fields around a crack-tip in FGM are basically described by the fracture mechanics parameters (K and J) as well as in non-FGM,using the mechanical properties of the material at the crack-tip. (3) The size of singular field decreases with an increase in the gradient of the mechanical properties. This suggests that the applicability of fracture mechanics such as small scale yielding condition and validity of J-integral is affected by the gradient.
2. Tensile tests and fracture toughness tests were carried out on seven kinds of glass particle reinforced nylon 66 composites. The stress-strain response, mechanical properties and fracture toughness of the composites depend on the particle volume fraction and the treatment of interface between the particles and matrix.
3. FGMs were made by joining four kinds of glass particle reinforced nylon 66 composites by hot press, and three point bending tests and fracture toughness tests were carried out on the FGMs. It was suggested that the strength of the FGM should be evaluated based on the analytical results taking account of the gradient and the fracture process in FGM can be different from that in non-FGM.
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