This paper on "A Finite Element Approach for Predicting Delamination Growth" was presented at the NAFEMS World Congress on Design, Simulation & Optimisation: Reliability & Applicability of Computational Methods - 9-11 April 1997, Stuttgart, Germany.

Abstract

For more brittle composites such as carbon fibre reinforced epoxy laminates it is shown that criteria based on elastic fracture mechanics are an appropriate tool for predicting delamination growth under quasi-static and fatigue loading. The criteria are based on the distribution of the local energy release rate, which is obtained using the virtual crack closure method, implemented in a finite element analysis. For quasi-static loading the concept has been verified by analyzing delamination fronts of the well known unidirectionally reinforced double cantilever beam specimen. The experimentally observed delaminations show contours for which the energy release rate is constant along the front. For cyclic loading experiments have been performed utilizing a specimen that contains a ply cut and an adjacent deliberate delamination. Plots of measured delamination progression per load cycle versus computed energy release rate have been included in a Paris Law diagram as obtained experimentally using simple specimens for material characterization. The results lie well within the scatter band of the experimentally determined Paris Law.