Analysis of Orthogonally Cracked Laminates Under Tension

The problems of stiffness reduction and stress analysis of cross-ply fiber composite laminates, where all plies are cracked in fiber directions, are treated by a variational method on the basis of the principle of minimum complementary energy. The Young’s modulus obtained is a strict lower bound but is expected to be close to the true value on the basis of experience with a previous analysis. Approximate values of Poisson’s ratio and internal stresses have been obtained. The latter reveal important tendencies of continued failure by delamination.