Property Degradation of Anisotropic Composite Laminates with Matrix Cracking. Part 1: Development of Constitutive Relations for (θm/90n)s Cracked Laminates by Stiffness Partition

The study on property degradation of damaged composite laminates is extended to anisotropic laminates with matrix cracking. In Part 1 of the paper, an idea of “stiffness partition” is proposed to deal with the puzzle that the in-plane normal response is coupled with the shear response of the laminates. For (θ m/90 n), laminates containing transversely cracked layers under general in-plane loading, the constitutive relations are derived and the effective stiffnesses are expressed as the functions of crack density.