The objective of this paper is to investigate the contribution/role of the crack closure and the fibre bridging effects
in stress-ratio influence in mode I delamination growth in carbon/epoxy composite laminates. The crack closure effect
has been assessed by the identification of the non-linearity in the compliance curve of the double cantilever test
specimen after the delamination extension. The effect of fibre bridging was investigated by cutting the bridging fibres
during fatigue delamination. The fatigue test data was process using fracture mechanics principles. The delamination
growth rate in laminates was characterized using approach of strain energy release rate. The results of the experiments
of fatigue delamination growth with bridging fibres and un-bridged fibres have been compared for different
fatigue stress-ratios. The results show that crack closure only occurs at lower stress ratios. Fibre bridging does not
affect the stress ratio however the crack rate was decreased in this case.