Void nucleation by inclusion debonding in a crystal matrix

TLDR

The study investigates how stress triaxiality determines whether decohesion or shear localization occurs first. A numerical micromechanical model with independent constitutive laws for matrix, particles, and interface is used to perform plane‑strain analyses of a doubly periodic array of rigid cylindrical particles in a crystal matrix with three slip systems, comparing predictions to an isotropic hardening flow theory and exploring two interface shear behaviours (periodic and decohesive). The crystal model shows that shear localization at the particle‑matrix interface can inhibit decohesion by producing large localized strains.

Abstract

In a numerical micromechanical study of void nucleation, a framework is used where constitutive relations are specified independently for the matrix, the void-nucleating particles and the interface. Plane strain analyses are carried out for a doubly periodic array of circular cylindrical particles. The particles are taken to be rigid and the elastic-plastic deformations of the matrix are described in terms of continuum crystalline plasticity, using a planar crystal model that allows for three slip systems. Comparison is made with void-nucleation predictions based on a corresponding flow theory of plasticity with isotropic hardening. The crystal model can give rise to shear localization at the particle-matrix interface and shear localization, which leads to large localized strains in the matrix, is found to inhibit decohesion. The role of the triaxiality of the stress state in determining whether decohesion or localization occurs first is investigated. A parameteric study is also carried out for a crystal matrix using two descriptions of the interface shear behaviour; one is periodic in the shear displacement across the interface, while the other allows for shear decohesion.