Finite Element Analysis of Delamination Growth in a Multidirectional Composite ENF Specimen

Abstract

Two different finite element models have been applied to the analysis of delamination growth in a multidirectional graphite/epoxy ENF specimen, which has previously been investigated experimentally. For a more accurate computation of energy release rates along the delamination front, and particularly the individual mode contributions, a layered 3-D shell finite element has been used. A 2-D finite element, based on Reissner-Mindlin plate theory, has been employed for simulation of the delamination growth. This element incorporates a process layer in which the delamination can grow. The virtual crack closure method is employed in both models to compute the energy release rates along the delamination front. It is postulated that these energy release rates control the development of the shape of the delamination front, as well as the final unstable growth of the delamination, as observed in the experiment. By a comparison between simulation and experiment it is found that in the present case of pure shear mode (combination of Modes II and III) the Griffith criterion predicts correctly the global delamination growth.