Prediction of compressive strength of carbon-epoxy laminates containing delamination by using a mixed-mode damage model

It is well known that composite laminates are easily damaged by low-velocit y impact. The internal delaminations can drastically reduce the compressive strength of laminates. In this study, a numerical analysis for predicting the residual compressive strength of delaminated plates is proposed. The de laminated interfaces are modelled by using interface elements connecting th e three-dimensional solid elements modelling the composite layers. Delamina tion propagation is modelled by using a damage model based on the indirect use of fracture mechanics. Due to the complex stress state of the problem, a mixed-mode analysis including the three modes of fracture was considered. Experimental studies were performed on carbon-epoxy [0(4), 90(4)](s) and [ 90(4), 0(4)](s) laminates. They included low-velocity impact tests, followe d by X-ray damage characterisation and compression tests. Good agreement be tween experimental and numerical analysis was obtained. (C) 2000 Elsevier S cience Ltd. All rights reserved.