The Effect of Temperature on Fatigue Strength and Cumulative Fatigue Damage of FRP Composites

Polymer-matrix composites are viscoelastic materials and their mechanical properties are significantly influenced by temperature. The present study intends to investigate the effect of temperature on cumulative fatigue damage (D) of laminated fibre-reinforced polymer (FRP) composites. The fatigue strength (S-N relation) of FRP composite laminates was formulated with temperature-dependent parameters. The effect of temperature was further included in the fatigue damage approach formulated earlier by Varvani and Shirazi. The analysis was developed to assess the fatigue damage of FRP composites at various temperatures (T). Inputs of the proposed analysis included temperature-dependent parameters including Young's modulus (E), ultimate tensile strength (sigma(ult)), and fatigue life (N-f). The proposed temperature-dependent terms and equations were evaluated with the experimental data available in the literature. Temperature dependant-parameters of Young's modulus, ultimate tensile strength, and S-N relation were found to be responsive when used for unidirectional, cross-ply, and quasi-isotropic FRP laminates. The proposed fatigue damage model was examined using six sets of fatigue damage data and was found promising to predict the fatigue damage of unidirectional (UD) and orthogonal woven FRP composites at different temperatures. (C) 2010 Published by Elsevier Ltd.