Origin of Plasticity Length-Scale Effects in Fracture

Fracture in metals is controlled by material behavior around the crack tip where size-dependent plasticity, now widely demonstrated at the micron scale, should play a key role. Here, a physical origin of the controlling length scales in fracture is identified using discrete-dislocation plasticity simulations. Results clearly demonstrate that the spacing between obstacles to dislocation motion controls fracture toughness. The simulations support a continuum strain-gradient plasticity model and provide a physical interpretation for that model's phenomenological length scale. Analysis of a dislocation pileup under a stress gradient predicts the yield stress to increase with increasing obstacle spacing, physically rationalizing the simulations.


Published in:
Physical Review Letters, 105
Year:
2010
ISSN:
0031-9007
Keywords:
Laboratories:




 Record created 2014-11-07, last modified 2018-03-17


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