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-velocity 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 delaminated interfaces are modelled by using interface elements connecting the three-dimensional solid elements modelling the composite layers. Delamination 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 [04, 904]s and [904, 04]s laminates. They included low-velocity impact tests, followed by X-ray damage characterisation and compression tests. Good agreement between experimental and numerical analysis was obtained.