Interface delamination vs. bulk cracking along wavy interfaces

Abstract

This paper analyzes the competition between bulk cracking and interface delamination along a wavy interface. The simulations embed cohesive elements throughout the entire mesh of conventional elements, such that crack paths emerge as a natural outcome of the simulations. The shape of interface is described using a sinusoidal wave form, with amplitude-to-wavelength ratios ranging from zero to one half. Asymptotic bimaterial crack tip fields are imposed at distances far greater than either the interface wavelength or cohesive rupture zone size, thus generating results for brittle fracture near asperities much smaller than the parent crack length. Results are presented for the far-field energy release rate that drives cracking (both along the interface and into the bulk), as a function of the interface amplitude, the position of crack tip, and the relative toughness of the interface and the bulk. Regime maps are illustrated that indicate the crack path as a function of the bulk-to-interface toughness ratio, along with the associated far-field energy release rate needed to drive failure.