1997 Fiscal Year Final Research Report Summary
Fracture Toughness Control in Functionally Gradient Material
| Project/Area Number |
07045018
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | University-to-University Cooperative Research |
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| Research Field |
Structural/Functional materials
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
WATANABE Ryuzo Graduate School of Engineering, TOHOKU UNIVERSITY,Professor, 大学院・工学研究科, 教授 (20005341)
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| Co-Investigator(Kenkyū-buntansha) |
INOUE Kanryu University of Washington, Department of mechanical Engineering, Professor, 工学部, 教授
TAYA Minoru University of Washington, Department of mechanical Engineering, Professor, 工学部, 教授
KOBAYASHI Al ワシントン大学, 工学部, 教授
LI Jing-Feng Graduate School of Engineering, TOHOKU UNIVERSITY,Associate Professor, 大学院・工学研究科, 助教授 (50241542)
KAWASAKI Akira Graduate School of Engineering, TOHOKU UNIVERSITY,Professor, 大学院・工学研究科, 教授 (50177664)
KOBAYASHI Albert S. University of Washington, Department of mechanical Engineering, Professor
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| Project Period (FY) |
1995 – 1997
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| Keywords | functionaly graded materials / composite materials / fracture toughness / thermal shock resistance / thermal residual stress relaxation / mechanical evaluation / fracture mechanics / indentation microfracture |
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| Research Abstract |
The international collaborative work between Tohoku University and The University of Washington on the evaluation of fracture toughness of FGMs were performed for three years with sharing research subjects between both contributors. Tohoku University took charge of the fabrication of FGM test pieces, testing of thermal shock property by burner heating test, as well as the valuation of the fracture toughness of FGMs by newly devised repeated Vickers indentation technique. The University of Washington, on the other hand, took part in the precise assessment of the fracture resistance that will be induced by the composition-graded layr. An unconventioanl hybrid approach using simultaneously optical measurement and numerical aclculation.
The burner heating thermal shock test on a FGM of zirconia/stainless steel showed that the initiation of cracks depends on the thermal stress generation and on defect distribution within the material. The formation of vertical cracks on the ceramic surface during cooling period of the burner heating test were observed, and the propagation of the cracks was found to be effectively suppressed by the graded layr. The repeated Vickers indentation test provides us easy and fast assessment of the fracture toughness of FGMs. Micromechanical and fracture mechanical considerations showed that the repeated Vickers indentation method is suitable for the assessment of the fracture toughness of FGMs particularly for the thin FGM layrs. The hybrid method provides us the more detailed information on the propagation of the cracks in the graded layr, and will be a viable approach for the clarification of the mechanisms of the crack propagation and its cessation.
The present collaborative work has provied fundamanetal information on the fracture mechanics of FGMs, and will contribute much to the progress of the FGM researches.
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Research Products
(12 results)
