Identification and forecast of delamination in composite laminates by an interlaminar interface model

For the forecasting of delamination initiation and propagation, a previously defined meso-scale damage model sf composite laminates is used. At the meso scale, the laminate is described as an assembly of damageable layers and interlaminar interfaces. The aim of this work is to identify precisely the interlaminar interface model for +/-theta interfaces, with theta = 0 degrees, 22.5 degrees and 45 degrees being the relative directions of the fibres of adjacent plies. This identification is based on initiation and propagation delamination tests. Our analysis of the conventional propagation tests makes use of the links existing between the critical-energy release rates and some of the model's parameters. In taking into account the part of the energy dissipated inside the layers, the interfaces can be classified into two categories. the 0 degrees/0 degrees interfaces of brittle behaviour, and the interfaces at disorientated angles whose critical-energy release rate is greater. Standard edge-delamination tension tests are also conducted and analysed in order to identify the other parameters of the interface damage model. (C) 1998 Elsevier Science Ltd. All rights reserved.