A procedure for the simulation of fatigue crack growth in adhesively bonded joints based on a cohesive zone model and various mixed-mode propagation criteria

This work deals with the simulation of fatigue crack growth (FCG) in bonded joints. In particular a cohesive damage model is implemented using the commercial software Abaqus, in order to take into account the damage produced by fatigue loading. The model is two dimensional and it is assumed that crack growth is confined to a straight bond line. The crack growth rate is evaluated using Paris-like power law expressed in terms of strain energy release rate. The crack growth rate is then transformed into variation of the damage distribution over the cohesive zone, leading to an equivalence between an increment of crack length and an increment of damage. The model also takes into account mixed-mode I/II loading conditions. In this work the validity of the model is tested by comparison with theoretical trends for conditions of pure mode I, pure mode II and mixed-mode loading. In the case of mixed-mode conditions, three models are implemented for the crack growth rate computation. The results of the models are in very good agreement with expected trends, therefore the model is adequate to simulate fatigue crack growth behaviour of bonded joint.