The background to the third world-wide failure exercise

The authors have recently completed two world-wide failure exercises, which dealt with benchmarking recognised failure criteria under two-dimensional and three-dimensional loadings, respectively. A new phase, called the third world-wide failure exercise' is currently underway to fill some of the major gaps identified in the previous activities. The third world-wide failure exercise is concerned with highlighting the degree of maturity of the current capabilities of 12 internationally recognised methods for modelling various aspects of damage in composite materials. Such problems include matrix cracks due to thermal and mechanical loads; delamination; ply constraint and stacking sequence effects; loading and unloading phenomena; failure due to stress gradients (in particular the hole size effect). The topics addressed within the third world-wide failure exercise represent an extremely important and crucial area for advanced modelling and virtual testing of composites. The third world-wide failure exercise runs in two stages (1) Part A which is devoted to providing full details and a comparison between the 12 theories together with their blind' predictions, made by their originators, for a challenging set of test problems and (2) Part B which is concerned with comparing the theoretical predictions with experimental results and assessing the accuracy and maturity of the methods. This paper provides details of the background to third world-wide failure exercise, the process of completing Part A and a summary of key conclusions.