2016 Fiscal Year Final Research Report
Quantitative evaluation of local lattice instability in mode I crack tip
| Project/Area Number |
26420014
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Gifu University |
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Principal Investigator |
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| Project Period (FY) |
2014-04-01 – 2017-03-31
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| Keywords | 局所格子不安定 / き裂 / シリコン / マグネシウム / 応力拡大係数 / 不安定変形モード |
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| Outline of Final Research Achievements |
Toward the new fracture mechanics in the atomic scale, we performed various molecular dynamics simulations on mode I crack in bcc-Fe, diamond-Si and hcp-Mg and discussed their different behavior from the original viewpoint of local lattice instability. The atomic elastic stiffness (AES) is defined as the second order derivatives of the energy of each atom and the negative eigenvalue of the AES means the existence of unstable deformation path. The unstable area of Si is very localized to single lattice, compare to that in bcc-Fd which is wide butterfly shape of a few atomic lines around the crack tip. The area of hcp Mg is also localized for the brittle cracking in the basal plane while it is also widely spread in the butterfly shape for the ductile dislocation emission in the prismatic plane. We've succeeded to visualize the unstable deformation mode by the principal axis of the strain tensor [eij], of which components are the eigenvector of the negative eigenvalue atoms.
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| Free Research Field |
計算材料科学，固体力学
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