Delamination in Thickness Tapered Composite Laminates

The structural performance of thickness-tapered laminates has been investigated using an energy-based damage tolerance methodology. The geometry studied is a thin laminate with discontinuous internal plies and a through-width delamination embedded at the interface between continuous and discontinuous sublaminates. An analytic model, based on shear deformation plate theory and linear-elastic fracture mechanics is employed to determine the Mode I and Mode II components of strain energy release rate. A two-dimensional plane strain finite element analysis is conducted to confirm the accuracy of the analytic predictions. The resulting pure mode strain energy release rates are combined with a mixed-mode growth criterion to predict the axial load required to induce delamination growth. Finally, the analytic and numerical model were used to predict failure in a delamination critical test specimen. Reasonable agreement of the actual and predicted failure loads was observed.