Inter-relationships among elastic constants for symmetrical or unsymmetrical laminates with cracked 90-plies

Abstract

The relations between the stiffness components of a symmetrical or unsymmetrical laminate having trans-verse matrix cracks only in the 90-degree laminas are explored in this work. The crack closure condition for these laminates under membrane and bending deformations is established to obtain the interrelationships. These equations also link the in-plane equivalent Young’s moduli and the Poisson’s ratios of balanced symmetric laminates. Cracks in off-axis laminas are not considered here. The present relations are validated using numerical data reported in the literature. Each inter-relationship can be used to obtain one elastic property when other property was experimentally measured or analytically calculated.