How to Model Delamination Using Cohesive Elements

A procedure for setting up cohesive-zone elements at ply interfaces to model delamination initiation and propagation in composite laminates.

Advanced Damage & Failure8 min read

how-todelaminationcohesive zonecohesive elementscompositeFEA

When to use this guide

Use this guide when modelling delamination with cohesive-zone elements in commercial FEA.

Identify the interfaces at risk of delamination — from geometry, stress analysis, or impact
Insert cohesive-zone elements at these interfaces — between the ply layers
Define the cohesive traction-separation law — initial stiffness, peak traction, fracture energy
Set the initiation criterion — quadratic interaction of normal and shear tractions
Set the damage evolution — energy-based with mixed-mode criterion (power law or B-K)
Provide Mode I and Mode II fracture energies (G_Ic, G_IIc) from DCB and ENF tests
Set the cohesive stiffness — high enough for accuracy, not so high for numerical issues
Mesh: ensure enough elements in the process zone — check mesh sensitivity
Run a single-interface verification — DCB or ENF simulation
Document the cohesive parameters and their calibration source