| Project/Area Number |
62302025
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
材料力学
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
SAKATA Masaru Tokyo Institute of Technology, 工学部, 教授 (90016296)
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| Co-Investigator(Kenkyū-buntansha) |
ABE Hiroyuki Tohoku University, 工学部, 教授 (00005266)
OTSUKA Akio Nagoya University, 工学部, 教授 (60022993)
KITAGAWA Hiroshi Osaka University, 工学部, 教授 (30029095)
MIYAMOTO Hiroshi Science University of Tokyo, 理工学部, 教授 (70010593)
AOKI Shigeru Tokyo Institute of Technology, 工学部, 教授 (90016436)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥8,800,000 (Direct Cost: ¥8,800,000)
Fiscal Year 1988: ¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 1987: ¥4,400,000 (Direct Cost: ¥4,400,000)
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| Keywords | Ductile Fracture / Finite Element Method / Large Deformation Analysis / Slip line Theory / Process Zone / Intense Strain Region / Gurson's Yield Function / Void Volume Fraction / Crystal Model / Mixed Mode / 混合モード / 局所化 / J積分 / 楔形き裂開口 / ボイド率、混合モード / き裂 / 塑性変形 / 混合モード破壊 / 破壊進行域 / 空孔率 / 有限要素法 |
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| Research Abstract |
It is the purpose of the present research program to investigate analytically the deformation and fracture behavior at the crack-tip of tough-materials, to make a comparison with the experimental results, and to propose a criterion for ductile fancture at the crack-tip. Large deformation finite element analyses are performed to study deformation and microvoid concentration properties near a notch or a crack-tip under opening or mixed mode loadings with Gurson's constitutive equation used for simulating nucleation and growth of micrvoids. A macrovoid is also assumed to be located near the crack-tip in order to examine its effect on deformation and fracture behavior of crack-tip. It is shown that under mixed mode loadings one corner of a crack-tip sharpens while the other corner blunts, and the strain and void volume fraction become concentrated at the sharpened corner with the increase of mode II component. A macrovoid near the blunted corner grows rapidly and a strong interaction is evidenced with microvoid fraction concentrated at the location between the macrovoid and blunted crack corner whereas a macrovoid near the sharpened cormer is found to have little effect on crack-tip deformation and fracture properties. A generalized crack-tip opening displacement and other quantities are proposed as parameters that control onset and growth of a crack under mixed mode loadings and are compared with the experimental results. Among these parameters, the critical void fraction, the condition of shear localization, the plastic work at the crack-tip, and the generalized crack-tip opening displacement are thought to be candidates for ductile fracture criterion. Further investigations will be required bofore a definite conclusion can be drawn.
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