Modelling of failure in long fibres reinforced composites by X-FEM and cohesive zone model

Crack nucleation and growth in long Fibre Reinforced Composites (FRC) are investigated using the extended finite element method (XFEM) and the cohesive zone model. This makes it possible to model cracks within a finite element without the requirement of either remeshing or aligning the mesh with the interface. The level-set concept is used to localise the fibre/matrix interfaces and to perform the enrichment. The jump in deformation, at the interface, is enriched by an absolute function and the jump in displacement is enriched by a Heaviside function. The problem is discretized by means of two-dimensional finite elements in the plane strain framework and the fibres are considered as perfectly bonded to the matrix. The transition between perfectly bonded interface and debonded interface is governed by a cohesive zone model. The obtained results were compared to the existing analytical results and then extended to more complex FRC configurations. It was found that the proposed approach is accurate and sensitive to the interaction between fibres. As a result, the crack is correctly and quite easily tracked.