Ply-By-Ply Delamination Morphology In Composite Laminates Under Low-Velocity Impact

The residual strength of composite laminates following low-velocity impact is affected by the location and size of individual delaminations. This study presents a first step towards an empirical model for the impact damage morphology of individual delaminations. To this end, the total mismatch angle, defined
as the sum over the full stacking sequence of the mismatch angle at each interface, is used to categorize the potential for delamination. Impact tests have been conducted on specimens with various different stacking sequences, selected to have a variety of different total mismatch angles. Impact tests were conductedat increasing impact energies, to evaluate the effect of energy level on individual delamination size derived from non-destructive inspections. Results indicate that the morphology of individual delaminations depends solely on the fibre orientation of the bounding plies and is independent of overall stacking
sequence of the laminate, ply-percentages, the through-the-thickness location of the delamination within the laminate and impact energy. The extent of delamination at each interface is significantly influenced by impact energy and the number of interfaces available for delamination.