Application of progressive fracture analysis for predicting failure envelopes and stress–strain behaviors of composite laminates: a comparison with experimental results

The theoretical predictions, published in Part A of the failure exercise, are compared with experimental results provided by the organizers of the exercise. Two computer codes, ICAN and CODSTRAN, developed at NASA (Glenn Research Center at Lewis Field), were applied to predict the damage initiation, damage growth and global structural fracture in a wide range of multidirectional laminates. CODSTRAN was employed to predict (I) seven biaxial failure envelopes of [0°] unidirectional and [0°/±45°/90°]s, [±30°/90°]s and [±55°]s multi-layered composite laminates and (II) seven stress–strain curves for [0°/±45°/90°]s, [±55°]s, [0°/90°]s and [±45°]s laminates under uniaxial and biaxial loadings. In general, CODSTRAN gave reasonable predictions for cases where final failure was dominated by fibre fracture. There was, however, large discrepancy between the predicted and measured failure strengths and strains for cases where failure was dominated by matrix failure. Some of the discrepancy is attributed to (a) the effect of residual matrix stiffness that is discounted in simulations and (b) sensitivity of the specimens to the presence of biaxial stress state in certain cases.