Assessing delamination growth under cyclic loading

To progress towards a slow-growth design basis for aircraft composite structures, the growth of typical damages must be predictable under service conditions. A review of limited experimental data available in the literature, mainly uniaxial coupon data, shows that the growth of delaminations or disbonds under cyclic loading is systematic and thus should be predictable. One such prediction was made here using a variant of the Hartman-Schijve equation. In the cases considered here, a simple metric namely delamination/debond length correlated to the number of cycles applied. Further investigations are required, particularly of representative aircraft structures.