Mode II fatigue delamination behaviour of composite multidirectional laminates and the stress ratio effect

•Mode I fatigue delamination tests are conducted and mode II R-curve behaviour of fatigue delamination has been observed.•A fatigue delamination model is proposed to characterize the combined effects of fiber bridging and stress ratio on the mode II fatigue delamination growth behaviour.•All fatigue data collapse into one single master curve in the log–log plot if using the proposed model.•The model has been further validated by extra public fatigue data of other material type and interfaces.