Results on the Influence of Crack Tip Plasticity During Dynamic Crack Growth.
BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING
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Dynamic fracture processes in structural materials are often described in terms of the relationship between a measure of the crack driving force and the crack tip speed. In this article, ongoing research directed toward establishing a basis for such a relationship in terms of crack tip plastic fields is described. In particular, the role of material inertia on a small scale as it influences the perceived fracture resistance of a rate independent material is discussed. Also, the influence of material strain rate sensitivity on the development of crack tip plastic deformations, and the implications for cleavage propagation and arrest in a material that can undergo a fracture mechanism transition, is considered. The discussion is concluded with mention of a few outstanding problems in the study of dynamic fracture, including some recent experimental evidence that the traditional crack tip characterization viewpoint of fracture mechanics may be inadequate under very high rate loading conditions. Keywords Dynamic fracture, Dynamic crack propagation, Elastic-plastic fracture, High strain rate fracture, Crack arrest.