Effect of Adhesive Layers on Impact Damage in Composite Laminates

Adhesive layers were included along the interfaces of a baseline graphite/epoxy [0 5 /90 5 /0 5 ] laminate for impact study. Impacted specimens were sectioned longitudinally and transversely for observation of the damage modes. The existence of adhesive layers resulted in the following effects: delamination was effectively suppressed up to very high impact velocities; matrix cracking in the upper lamina was greatly reduced; and the contact area appreciably increased thereby reducing the stress concentration effect. An apparent disadvantage in using adhesive layers was found; that is, the bending crack in the bottom lamina which could branch out into delamination cracks when adhesive layers Were absent tended to penetrate the middle lamina and break fibers.