A micromechanistic perspective of cohesive zone approach in modeling fracture

Cohesive Zone Models (CZMs) are increasingly being used to simulate fracture and fragmentation processes in metallic, polymeric, ceramic materials and composites thereof. Instead of an infinitely sharp crack envisaged in linear elastic fracture mechanics, CZM assumes the presence of a fracture process zone where the energy is transferred from external work both in the forward and the wake regions of the propagating crack. In this paper, some of the mechanistic and computational issues in the application of CZM to model failure and fracture in real materials are discussed. In specific we address the issue of CZM in relation to micromechanical processes that are active in and around fracture process zone. We also examine the distribution of total dissipation energy, i.e. inelastic strain energy, and cohesive energy, the latter encompassing the work of fracture and other energy consuming mechanisms within the fracture process zone. It is clearly shown that a thorough understanding of the energetics and underlying micromechanisms of the fracture processes are essential for accurately simulating fracture and failure in materials and structures.