Influence of opposing wave nesting in compression-loaded composites

Under static compression loading, large interlaminar normal and shear strains have been shown to occur as a result of layer waviness. Previous research has shown that nested (in-phase) layer waves produce roughly the same maximum interlaminar shear and normal strain values as a single wave of similar geometry. This paper addresses the influence of wavy layers that are out-of-phase, or mirrored about the neutral axis. Experimental results using moire interferometry reveal that opposing (out-of-phase) waves also produce roughly the same maximum interlaminar shear and normal strain values as a single wave of similar geometry, while analytical predictions using finite element techniques show a trend that partially disagrees. This supports the conclusion that although mechanical performance in wavy composites will be primarily due to the amplitude of individual waves, local interactions among waves at certain separations may produce an important contribution.