Delamination growth and its effect on crack propagation in carbon fiber reinforced aluminum laminates under fatigue loading

Abstract

The fatigue crack growth in Fiber Reinforced Aluminum Laminates (FRALL) involves two inter-related damage processes, i.e. crack growth within the aluminum layer and delamination growth between the aluminum layer and the composite core. In this study, the fatigue crack growth behavior in Carbon fiber Reinforced Aluminum Laminates (CARALL) was analyzed using a simplified model which takes both fiber bridging effects and the delamination propagation into account, supplemented by an iterative calculation scheme. Results indicated that the delamination growth during the fatigue process exhibits an effective “self-adjusting” property such that the size of the delamination zone would converge rapidly, irrespective of the initial size. This is explained in terms of the decrease in the fiber bridging force, the driving force for delamination, as the delamination size increases. In general, however, the effect of delamination growth on the fatigue crack growth in CARALL was shown to be of secondary significance as compared to that of the stiffness of the composite core. It was argued that qualitative conclusions should be applicable to FRALL in general.