Abstract
<jats:p>A model for the nucleation of a combined crack in the total elastic field of a negative wedge disclination and a blocked planar pile-up of lattice dislocations is developed. A criterion for crack nucleation in the total elastic field of a disclination and a locked dislocation pile-up with a small number of dislocations is proposed, applicable to materials with a fragmented structure. The crack nucleation conditions are analyzed as a function of the number of dislocations in the pile-up, external stress, disclination strength, and the screening radius of its elastic field. It is established that in the limiting case of large pile-ups of lattice dislocations and the absence of disclinations, the crack nucleation criterion transforms into Stroh»s criterion for crack nucleation at the pile-up head.</jats:p>