Modeling Delamination Growth in Composite Panels subjected to Fatigue Load

One of the most critical aspects of composite structures is indeed associated to delamination phenomenon, especially with reference to their fatigue behavior. As a matter of facts, delaminations are strongly influenced by the fatigue induced degradation phenomena which can lead to a significant increase of delaminated area with the number of cycles, reducing the structural load carrying capability. In the present paper, an advanced numerical approach, very similar to the Paris Law formulation and based on the Energy Release Rate, is presented. The proposed formulation, in the frame of a geometrical non-linear analysis, is able to take into account the local damage accumulation along the delamination front in order to evaluate the delamination growth under fatigue loading conditions. In order to test the effectiveness of the proposed numerical approach, the fatigue behavior of a delaminated panel with a central hole has been simulated and the obtained numerical results have been compared with literature experimental results.