Effect of the shear and coupling elements of the Aij and Dij matrices on the impact behavior of glass, aramid and hybrid fabric composites

The impact behavior of glass, aramid and glass–aramid hybrid fabric epoxy matrix composites was evaluated. Delamination was identified as the main macroscopic failure mode of the composites. A simple relationship based on the macromechanical behavior of laminated composites was established, relating coupling—A26, D26—and shear—A16, D16—elements of the extensional and bending stiffness matrices to the total energy absorbed at impact. The results obtained show that the A66/D66 ratio is a relevant parameter of concern, correlated with the behavior of the composites under impact. Additionally, the coupling matrix Bij was shown to restrain the macroscopic delamination of the composites.