Ductile failure in a constrained metal layer under mixed mode loading

Abstract

A ductile metal layer joining two brittle ceramic blocks is a common architecture in engineering applications. The failure process of such a constrained ductile layer under mode I loading was studied in a previous work. In this paper, the effect of mode mixity on ductile rupture of the metal layer is investigated. A finite deformation, finite element analysis is carried out under plane strain, small-scale yielding conditions. The rate-independent version of the Gurson model that accounts for microvoid nucleation, growth and coalescence is employed to represent the behaviour of the metal layer. The competition between two different ductile failure mechanisms, namely, far-field triaxiality-induced cavitation and classical near-tip void coalescence, is investigated in detail for different extents of mode mixity. The results show that far-field cavitation is the dominant mechanism under loading conditions that are close to mode I, while void coalescence near the notch tip becomes operative as the mode II component increases.