Structural cohesive element for the modelling of delamination in composite laminates without the cohesive zone limit

TL;DR

This paper introduces a new structural cohesive element for modeling delamination in composite laminates, allowing larger mesh sizes and reducing computational cost without sacrificing accuracy.

Contribution

A novel 3D cohesive element that overcomes the mesh density limit of standard models, enabling more efficient delamination simulations in composites.

Findings

Mesh size can be ten times larger with the new element.

Over 90% reduction in CPU time compared to standard models.

Accurate predictions maintained despite larger mesh sizes.

Abstract

Delamination is a critical mode of failure that occurs between plies in a composite laminate. The cohesive element, developed based on the cohesive zone model, is widely used for modeling delamination. However, standard cohesive elements suffer from a well-known limit on the mesh density-the element size must be much smaller than the cohesive zone size. This work develops a new set of elements for modelling composite plies and their interfaces in 3D. A triangular Kirchhoff-Love shell element is developed for orthotropic materials to model the plies. A structural cohesive element, conforming to the shell elements of the plies, is developed to model the interface delamination. The proposed method is verified and validated on the classical benchmark problems of Mode I, Mode II, and mixed-mode delamination of unidirectional laminates, as well as on the single-leg bending problem of a multi-directional laminate. All the results show that the element size in the proposed models can be ten times larger than that in the standard cohesive element models, with more than 90% reduction in CPU time, while retaining prediction accuracy. This would then allow more effective and efficient modeling of delamination in composites without worrying about the cohesive zone limit on the mesh density.