The predictive capability of failure mode concept-based strength criteria for multidirectional laminates

This contribution is a post-runner to the 'failure exercise'. It focuses on two aspects of the theoretical prediction of failure in composites [1-3]: the first is the derivation of failure conditions for a unidirectional (UD) lamina with the prediction of initial failure of the embedded lamina, and the second the treatment of non-linear, progressive failure of 3-dimensionally stressed laminates until final failure. The failure conditions are based on the so-called Failure Mode Concept (FMC) which takes into account the material-symmetries (by the application of invariants) of the UD-lamina homogenized to a 'material', and on a strict failure mode thinking. The results of the investigation are stress-strain curves for the various given GFRP-/CFRP-UD-laminae, biaxial failure stress envelopes for the UD-laminae, and initial as well as final biaxial failure envelopes for the laminates. In addition a brief comparison between Puck's and Cuntze's failure theory is presented by the authors themselves. (C) 2003 Elsevier Ltd. All rights reserved.