Fatigue life prediction of thick-section S2-glass/vinyl-ester composites under flexural loading

Fatigue life prediction of S2-Glass/Vinyl-ester composites has been studied analytically using the fatigue modulus concept. Traditionally it is assume d that the fatigue modulus degradation is a function of loading cycle only. In our present investigation, it is found that the fatigue modulus is not only a function of loading of cycle but also a function of applied stress l evel and thickness of the specimen. Using this concept, a practical and app licable method for predicting fatigue life is established. The method requi res two distinct parameters that arise from the mathematical formulation. T hese two parameters are determined in two ways. In one case, the parameters are determined using failure cycle numbers at two different stress levels. In the other case, the parameters are determined using fatigue modulus val ues at two different cycles at a particular stress level. These material pa rameters have been determined experimentally using both the procedures. Uti lizing the experimental data two appropriate functions for these two materi al parameters were obtained and incorporated into the life prediction equat ion. Fatigue life predictions using this method have been found to be withi n 10 percent of the experimental values. [S0094-4289(00)02404-X].