Effect of plasticity on cleavage crack growth resistance at an interface

Abstract

The mixed mode toughness of an interface joining an elastic–plastic metal to a solid which does not yield plastically is studied numerically for cases where fracture occurs by atomic separation. Thus, the length scale of the fracture process is typically much smaller than the dislocation spacing on the metal side of the interface. But even though the crack growth mechanism is brittle, the interface shows crack growth resistance due to plastic flow at some distance from the crack tip. It is assumed that the crack tip does not emit dislocations. Therefore, the numerical technique employed makes use of a thin elastic strip of material along the metal side of the crack tip, while the metal outside the strip is described by continuum plasticity. Most of the computations use an infinitely long elastic strip to represent the elastic core region around the tip, but the approximation of using a long strip is tested by comparison with a few analyses for a short strip.