Initial Energy Dissipation Mechanism at Crack Tip on the Ductile to Brittle Transition
The objective of this study is to investigate energy dissipation mechanisms that operate at different length scales during fracture in ductile materials. A dimensional analysis is performed to identify the sets of dimensionless parameters which contribute to energy dissipation via dislocation-mediated plastic deformation at a crack tip. However rather than use phenomenological variables such as yield stress and hardening modulus in the analysis, physical variables such as dislocation density, Burgers vector and Peierls stress are used. It is then shown via elementary arguments that the resulting dimensionless parameters can be interpreted in terms of competitions between various energy dissipation mechanisms at different length scales, for example between dislocation nucleation from a crack tip and dislocation nucleation from a Frank-Read dislocation source in the material close to the crack tip. Criteria are established which are used to determine the initial, and perhaps dominant, energy dissipation mechanism at a crack tip.
KeywordsFracture dislocation crack tip dislocation nucleation Frank-Read dislocation source ductile to brittle transition
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- Kysar, J. W. (2002) “Energy dissipation mechanisms in ductile fracture.” Submitted to J. Mech. Phys. Solids Google Scholar
- McClintock, F. A., and Argon, A. S. (1966). Mechanical Behavior of Materials, Addison Wesley, Reading, Massachusetts.Google Scholar
- Rice, J. R. (1965) “An examination of the fracture mechanics energy balance from the point of view of continuum mechanics.” Proceedings of the 1st International Conference on Fracture, Sendai, (eds. T. Yokobori, T. Kawasaki, and J. L. Swedlow), Japanese Society for Strength and Fracture of Materials, 1, 309–340.Google Scholar