Analysis of transverse cracking in cross-ply composite laminates

An analytical model based on the principle of minimum potential energy is developed and applied to determine the two-dimensional thermoelastic stress state in cross-ply composite laminates containing multiple equally spaced transverse cracks in the 90 degrees plies and subjected to tensile loading in the longitudinal direction. The model provides full field solution for displacements and stresses including the residual thermal stresses which in turn are used to calculate the strain energy release rate associated with various failure modes. The strain energy release rate criterion has been employed to evaluate the critical applied stresses for two of the possible fracture modes; self-similar extension of a pre-existing flaw and the formation of a new parallel crack. The computed results indicate that formation of new cracks never takes place until pre-existing cracks extend through the entire thickness of the 90 degrees plies. The predicted results of transverse crack density are in good agreement with the available experimental data.