1998 Fiscal Year Final Research Report Summary
Basic Theory for Dynamical Stability of Fracture Propagation
| Project/Area Number |
09640468
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
物性一般(含基礎論)
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
NAKANISHI Hiizu Kyushu Univ., Faculty of Science, Professor, 理学部, 教授 (90155771)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Dynamical Fracture / Stability / Pulse Propagation / Front line Stability / Surface Wave / Visco-Elasticity |
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| Research Abstract |
1. The surface wave for a visco-elastic material is studied analytically and by numerical simulations. It is found that there is no surface wave solution in the case that the effect of surface tension is larger than the effect of elastic stress. Such a situation is not very realistic for an ordinary solid material but can be realized in a gel, therefore it is expected that fracture dynamics is very different from an ordinary solid in the gel where the elasticity is very small.
2. Dynamical stability of the crack front line that propagates between two plates is studied numerically using the simple two-dimensional mass-spring model. It is demonstrated that the straight front line is unstable for low speed while it becomes stable for high speed. For the uniform model, the roughness exponent in the slower speed region is fairly constant around 0.4 and there seems to be a rough- smooth transition at a certain speed. For the inhomogeneous case with quenched randomness, the transition is gradual.
3. Dynamics of fracture propagation is analyzed in the case where the fracture surfaces restick after the fracture front has passed for Mode III fracture in the two-dimensional elastic material. It is found that the fracture speed is determined by the resticking condition in the case without dissipation.
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