Strain energy based failure criterion: Comparison of numerical predictions and experimental observations for symmetric composite laminates subjected to triaxial loading

An analytical model to predict the constitutive response, failure initiation and post-initial failure behavior of fibrous composites under triaxial loading has been developed based on a strain energy formulation. This paper highlights the means of developing several key parameters in the model and extends the model to include the effects of in-plane thermal residual stresses accumulated during the curing of composite laminates. The derivations of a set of consistent model input parameters for several composite material systems are described. A series of comparative stress-strain curves and failure envelopes are provided comparing model predictions to published experimental data. The strain energy based failure model is found to provide good agreement with the experimental observations studied in this work.