| Project/Area Number |
09305011
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 | Science University of Tokyo |
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Principal Investigator |
OKUMURA Hiroyuki Science Univ.of Tokyo, Faculty of Science & Technology, Professor, 理工学部, 教授 (00010679)
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| Co-Investigator(Kenkyū-buntansha) |
KANEKO Kenji Science Univ.of Tokyo, Faculty of Technology, Professor, 工学部, 教授 (40016803)
MACHIDA Kenji Science Univ.of Tokyo, Faculty of Science & Technology, Associate Professor, 理工学部, 講師 (50089380)
KIKUCHI Masanori Science Univ.of Tokyo, Faculty of Science & Technology, Professor, 理工学部, 教授 (90107540)
NAKASONE Yuuji Science Univ.of Tokyo, Faculty of Technology, Professor, 工学部, 教授 (10266918)
CHEN Daiheng Science Univ.of Tokyo, Faculty of Technology, Professor, 工学部, 教授 (90217266)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Fracture Surface Analysis / Dimple Fracture / Crack on Phase Boundary / Mixed Mode Crack / Constitutive Equation / Aging / Phase Boundary / Stress Singularity |
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| Research Abstract |
The fracture surface analysis is developed using laser microscope and scanning electron microscope, and the micro mechanism of the fatigue fracture process is studied. The dimple fracture process with the nucleation, growth and coalescence of voids are studied experimentally and numerically. The three-dimensional finite element program based on the deformation theory is developed for this purpose. The strength of SiC particle reinforced aluminum alloy is studied. The constraint effect of the elastic-plastic fracture mechanism is also studied by the similar method. It is shown that the constraint effect is related with the microscopic fracture behavior by the voids.
The effect of Young's modulus and Poisson's ratio on stress intensity factors of interface crack was discussed under various kinds of mixed-mode loading. The complex stress-intensity factor K associated with an elastic interface crack was discussed via different three approaches : the virtual crack extension method, modified
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crack closure integral and displacement extrapolation. A polynomial fit was proposed to evaluate the stress intensity factors at the midsection of specimen with an interface crack subjected to mixed-mode loading. The stress-intensity factors can be simply evaluated by the present polynomials.
For this three years, effects of loading conditions, temperature of test, heat-treatments and chemical compositions of the iron-materials including a few non-iron materials and polymers, on viscosity and aging of dominant factors in the constitutive equations, were investigated systematically and some of them were formulated. this is a great step up to construct a inelastic constitutive equations with effects on micro/macro-textures of composite materials.
In order to develop a new fracture theory to cover non-homogeneous structure with metallic fine organization in a meso-scopic region, the cooperator put his attention on the stress singularity occurring in an interface or a corner of jointed dissimilar materials. First, the cooperator used numerical method to analyze the elastic and the plastic stress singularity and the intensity of the singular stress field for various non-homogeneous structures. Secondly, the cooperator presented a new fracture criterion based on the singular stress field. The usefulness of the criterion is confirmed by experiment results. Less
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