A fatigue life prediction method was developed to predict fatigue life of 2.5 dimensional woven composites subjected to fatigue loading. This method consisted of unit-cell model

fatigue damage criterion and material property degradation technique. Stress analysis was performed by three dimensional finite element technology based on the unit-cell model. Modified three dimensional Hashin fatigue damage criterion and Mises criterion were adopted to identify fatigue damage separately for the yarns and matrix. The stiffness property sudden degradation rules were applied to establish the fatigue damaged material properties; the residual stiffness and strength models considering fiber volume fraction were used to establish the undamaged material properties. The coincidence of predicted fatigue life and experimental data was studied

and the comparison results validated the fatigue life prediction method. The results indicate that the tensile-tensile fatigue life in warp direction increases with the warp fiber volume fraction increasing

while weft fiber volume fraction has little effect on tensile-tensile fatigue life in weft direction.