Evaluation of interfacial fracture toughness using cohesive zone model

Interfaces play a critical role in determining the stiffness, strength and fracture properties of polymeric, metallic, and ceramic matrix composites. In this paper, while comparing the origin of interfaces in the three systems, attention is focused on the metal-(intermetal-) matrix composites. The roles of processing induced residual stresses, and the chemistry evolution during in service on the mechanical properties in general, and fracture properties in particular are delineated. Stress-based and energy-based failure criteria to model interfaces are described with examples drawn from Titanium matrix composites. Finally a detailed discussion on using cohesive zone models (CZMs) to describe fracture and failure of interfaces is presented. While it is contented that CZMs present the best alternative from physics and computational perspectives, it is emphasized that the choice of the specific form and parameters is very important.