Cohesive zone model

The Cohesive Zone Model (CZM) is one of the most important developments in fracture mechanics. It’s widely used to simulate how cracks start and grow in solid materials. Unlike traditional methods, CZM treats fracture as a gradual process, where the surfaces slowly separate across a small zone called the cohesive zone. This zone resists separation through cohesive forces, which are modeled using special elements placed between regular (bulk) elements. These cohesive elements don’t represent physical material they represent the forces that hold the material together as it starts to break apart.

CZM offers key advantages over conventional fracture methods like Linear Elastic Fracture Mechanics (LEFM) and Crack Tip Opening Displacement (CTOD). It can be used even when there’s no initial crack, and it’s suitable for modeling blunt notches and complex interface behaviors. It also allows for more realistic simulations where the size of the nonlinear zone near the crack tip matters something other methods often ignore.

In this short video (under 11 minutes), you’ll learn how to build a simple CZM model in Abaqus to simulate crack propagation. The approach is fast and works well even for large-scale models. The tutorial includes both the simulation output and the Abaqus CAE file, and it’s designed to be straightforward focused on practical use rather than deep theory.