Small scale yielding analysis for a disclination-nucleated Zener-Stroh crack interacting with a circular inclusion

Abstract

The elastic-plastic fracture behavior of a Zener-Stroh crack nucleated by a wedge disclination dipole interacting with a nearby circular inclusion is investigated. It is known that a disclination is a strong source of internal stresses and energy, one possible way for the relaxation of the stresses can be in the form of an initiated crack. In the current work, the nucleated Zener-Stroh crack is simulated by a series of edge dislocations with distributed dislocation method. The influence of the disclination is accounted through crack surface traction free condition. To improve the analysis accuracy, the Irwin plastic zone correction is employed to evaluate the elastic-plastic fracture behavior at the sharp crack tip. Von Mises yielding criterion is applied in the plastic zone area to judge the yielding occurrence. Numerical results are given to study the influence of the disclination strength, disclination dipole arm as well as material properties on the stress intensity factor (SIF), plastic zone size (PZS), and crack tip opening displacement (CTOD). It is found that the property of the wedge disclination dipole has great effect on the stress field and the elastic-plastic fracture behavior of the Zener-Stroh crack. Either disclination strength or dipole arm increases, the SIF, PZS, and CTOD will increase significantly. For the same disclination, if the nucleated Zener-Stroh crack has a longer crack length, the SIF, PZS, and CTOD could be smaller. For a Zener-Stroh crack nucleated between the inclusion and the disclination dipole, the interaction between the disclination and inclusion greatly influences the elastic-plastic fracture behavior. However, this influence highly depends on material combinations of the two phases.