Application of cohesive zone elements in damage analysis of composites: Strength prediction of a single-bolted joint in CFRP laminates

• An alternative strength prediction method is developed for bolted joints in CFRP laminates.
• The empirical dependency of conventional strength prediction methods is partly eliminated.
• The required inputs are the elastic properties, strengths and critical fracture energies.

Cohesive zone elements are implemented in 3-D finite element models in order to develop a strength prediction method for single-bolted joints in CFRP composite laminates. The motivation for using the CZEs is to avoid experimental correlation factors by directly simulating the subcritical damage mechanisms, which initiate and grow before the catastrophic failure of the joints. The CZEs, placed in the experimentally determined damage locations, receive shear loads and the corresponding shear stresses cause stress concentration relief around the hole boundary. Therefore, a simple maximum stress failure criterion is used to predict the final failure of the joints when the stress level at the 0° layers reaches the ultimate compressive strength. It is shown that the effect of various joint geometries and laminate lay-ups on the joint strength can be accurately accounted for by the method developed.