Fracture and indentation in single metal crystals (INVITED)

Abstract eng:
Cracks in elastic-plastic single crystals offer an opportunity to develop a fundamental understanding of plasticity under the extreme conditions of high plastic strain and plastic strain gradients. The asymptotic deformation fields near a crack tip in an elasticplastic single crystal adopt an angular sector structure centered at the tip that are strikingly different for stationary and quasistatically growing cracks. Herein we extend Prandtl’s analogy between a flat punch and a stationary crack to an angled indenter and quasistatically moving crack. Specifically, the angled indenter impinging into a material can be modeled asymptotically as a quasistatically closing crack. We present analytical asymptotic solutions to this boundary value problem and demonstrate that they are consistent with the predicted deformation state associated with the overall indentation deformation fields. Finally, we show that the predicted deformation state is consistent with experimental results of lattice rotation fields and associated densities of geometrically necessary dislocations.

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