Fatigue Property Model of Hybrid FRPs Based on Residual Strength Concept in View of Stress Ratio and Loading Sequence Effects

ABSTRACT Fatigue tests are conducted on hybrid carbon fabric CF3052/glass fiber EW250F reinforced epoxy 3238A laminated composites under constant amplitude loading at five stress ratios to examine fatigue behaviors, and under H–L, L–H, and H–L–H block spectrum loading to determine fatigue lives. The effects of stress ratio and loading sequence and damage mechanisms are analyzed and discussed from experiments. A novel fatigue property model based on residual strength concept is presented to reveal the effects of stress ratio and loading sequence on fatigue lives, and new progressive fatigue damage modeling algorithm incorporating fatigue property and residual strength failure criterion is devised to simulate fatigue damage progression. Relative deviations of predicted fatigue lives under H–L, L–H, and H–L–H block spectra are respectively 7.9%, 11.6%, and 20.5% from experimental mean values, in superior prediction accuracy over the traditional Miner rule, demonstrating the effective and practical usage of the proposed model.