Finite element study of the fibre-matrix interface behaviour of [10 degrees/90 degrees] laminated composites under tensile loading

A three-dimensional unit cell has been developed and modelled using the fin ite element method to investigate the interface failure behaviour of SiCf/S i3N4 composites under tensile loading at room and elevated temperatures. Th e model idealizes the composite as a regular rectangular array of fibres in 0 degrees and 90 degrees orientations embedded in the matrix. It introduce s three-dimensional contact elements between the fibre and the matrix to si mulate the interface conditions between the two phases. Slippage between 0 degrees and 90 degrees layers is also considered by introducing another set of contact elements at the layer separation planes. Two interface conditio ns, namely, infinitely strong and weakly bonded, are considered to establis h the correlation with the experimental data. To simulate the weak interfac e, the fibre and the matrix are assumed to slide over one another with shea r stress through the Coulomb mechanism. The same assumption has been adopte d for the layer separation planes. A finite element model utilizing these c oncepts has been developed. Stress-strain behaviour and the local stress di stributions at various ambient temperatures within the unit cell, are prese nted. The investigation has also been extended to include the effects of re sidual stresses in the finite element model. It is shown that the model yie lds results th at correlated reasonably well with the experimental data. (C ) 1998 Kluwer Academic Publishers.