Three dimensional finite element study of the behaviour and failure mechanism of non-crimp fabric composites under in-plane compression

The compressive behaviour and the mechanism responsible for failure of a [0,90]n non-crimp fabric (NCF) laminate are studied using a 3D finite element (FE) model of the representative unit cell at the mesoscopic scale. The tows of the unit cell were generated using a straight FE mesh taking into account the waviness of the fibres with the definition of the mechanical properties of each element according to the actual direction of the fibres. A parametric study has been carried out to evaluate the influence of the non-linear behaviour of the tows and of the fibre crimp on the compressive failure mechanism of the laminate. The numerical predictions are discussed and compared with experimental data. The results lead to think that the mechanism of failure of a [0,90]n NCF laminate under a pure compressive load is controlled by the shear strains that appear in the crimp part of the 0° tows. It is also found that the non-linear behaviour of the tows and the fibre crimp substantially contribute to the development of the potential failure initiation mechanism. A satisfactory agreement between the numerical and experimental compressive stress-strain curves is obtained for the highest fibre crimp angles considered.