Finite element analysis of damaged cross-ply composite laminates

The problem of transverse cracks in T300/5208 graphite-epoxy cross-ply laminates was studied using generalized plane strain finite element analysis. The degradation of elastic modulus, Poisson's ratio, shear modulus, and coefficient of thermal expansion was predicted and then compared with analytical models and experimental data. The elastic modulus was predicted to exhibit relatively small degradation as a function of crack density as compared to the Poisson's ratio, shear modulus, and coefficient of thermal expansion which were predicted to have large degradations.

The resulting state of stress was also studied for several crack spacings. Interlaminar stresses were predicted to form as a result of the free surface of the crack. The crack tip also caused all the nonzero stresses to exhibit singular behavior at the crack tip.