Matrix cracking induced by cyclic ply stresses in composite laminates

The objective of this paper is to review the wealth of experimental results obtained in our laboratory during the last 10 years and the related analyses. The relevant studies essentially involve a brittle-matrix composite (carbon/epoxy T300/914), intended as a model material for characterization under various experimental conditions. The physical and geometrical parameters governing the initiation, accumulation, growth and saturation of matrix cracks under cyclic mechanical loading have been identified. A shear-lag analysis, associated with an energy release rate criterion, is used to predict cracking development in each cross-ply laminate subjected to any fatigue loading. More recently, an experimental program has been achieved to characterize the damage development due to thermal cyclic loading. This investigation brought out the limitations of a purely mechanical approach for the prediction of matrix cracking due to cyclic thermal exposure.