A numerical approach to the disbonding mechanism of adhesive joints

The need for lightweight structures in aeronautics is leading to a strong interest in adhesively bonded joints. Incomplete knowledge of their fatigue behaviour is a major obstacle to their application. At present, the prediction of the disbonding growth is yet an open question. This work aims to develope a numerical model for the computation of the disbonding growth in an adhesive joint. The scope is calculating the energy release under quasi-static conditions in order to relate it to the fatigue disbond growth through the existing analytical models. A finite element model for the prediction of disbond growth under quasi-static loading has been implemented in Abaqus, by introducing a cohesive zone model which is able to capture the process zone around the crack tip and to enforce an energy-based failure criterion. The model, which had originally been developed for double cantilever beam specimens under mode I, was extended to mode II loading. Numerical simulations are validated by comparison with experimental results on double cantilever beam coupons in mode I and with literature results on end notched flexure coupons in mode II conditions. The results from tests and simulations are in accordance with each other. The presented model is a suitable option for the estimation of fracture mechanics parameters in cases in which complex geometry and loads prevent the application of analytical theories.