Numerical simulation of material separation using cohesive zone models

Abstract

This chapter will very briefly summarize the general foundations and developments of the cohesive zone model, which have been reported in literature during the past 50 years. According to the scope of the book, only material separation due to mechanical loading modeled by a cohesive interface will be considered, even though additional environmental effects may be taken into account. The reduction of the load bearing capacity of a cracked (or damaged) region by a separating interface is a strong simplification, but it reduces the complexity of the crack models significantly such that the model gained high interest in research and also in industry. The use of cohesive zone models for the simulation of crack propagation in engineering structures has first been reported in 1976. The increase in computer power, which promoted the use of the finite element method as well, has increased the possibilities in the application of the cohesive zone model. It is now used for almost all kinds of materials and many different processes, and it has undergone many extensions and improvements with respect to materials, loading conditions, numerical techniques, and mechanical formulations. After a short historical overview starting with the very beginning of the cohesive interface model, the chapter addresses several recent developments such as identification and use of traction-separation laws, mixed-mode behavior, unloading issues, and cyclic loading.