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 thermoelast ic stress state in cross-ply composite laminates containing multiple e qually spaced transverse cracks in the 90 degrees plies and subjected to tensile loading in the longitudinal direction. The model provides f ull field solution for displacements and stresses including the residu al thermal stresses which in turn are used to calculate the strain ene rgy release rate associated with various failure modes. The strain ene rgy 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 c rack. The computed results indicate that formation of new cracks never takes place until pre-existing cracks extend through the entire thick ness of the 90 degrees plies. The predicted results of transverse crac k density are in good agreement with the available experimental data.