Numerical investigation of progressive damage and the effect of layup in overheight compact tension tests

This work describes a numerical investigation into progressive damage development in notched fibre-reinforced composite laminates. A finite element approach is used which explicitly models the sub-critical damage in the form of delamination and splits using interface elements, and fibre failure using a progressive statistical failure theory. Failure predictions were made for Overheight Compact Tension (OCT) test specimens using five different layups made up from IM7/8552 carbon/epoxy pre-preg. Owing to the detailed modelling of the individual damage modes, their interaction is well characterised. The numerical results obtained compare well with detailed test observations, capturing delamination, intraply splitting and fibre breakage. By including the subcritical damage that occurs at the notch tip in the model, it is able to represent the effect on the stress concentration and hence to predict ultimate specimen failure.