Delamination testing and modelling for composite crash simulation

The availability of high performance low cost carbon fibre in materials such as non crimp fabrics (NCF) has led to renewed interest in advanced composites for automotive applications. A wide range of structural applications are possible; however, amongst other considerations the performance of these materials under crash and impact loading is a primary concern. For crashworthiness simulation of large scale composite structures compromise modelling methods are needed that can balance accuracy and modelling efforts with acceptable computational (CPU) costs. For this reason, a modelling technique is used that represents the laminate as a stack of plies using layers of shell elements. These layers are tied, at the ply interfaces, using special constraint elements to represent the mechanical elastic and delamination energy absorption characteristics of the resin rich interface. Delamination is an important aspect of composite integrity and, in order to assess this, a test program of candidate textile reinforced composites under Mode I, Mode II and mixed mode loading has been conducted. This data, together with ply failure data, has been used in the proposed model to simulate a complex demonstrator automotive structural component; details of the numerical models and example results are presented.