Fatigue Life Prediction of Thick-Section S2-Glass/Vinyl-Ester Composites Under Flexural Loading1

Abstract

Fatigue life prediction of S2-Glass/Vinyl-ester composites has been studied analytically using the fatigue modulus concept. Traditionally it is assumed 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 cycle but also a function of applied stress level and thickness of the specimen. Using this concept, a practical and applicable method for predicting fatigue life is established. The method requires two distinct parameters that arise from the mathematical formulation. These 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 values at two different cycles at a particular stress level. These material parameters have been determined experimentally using both the procedures. Utilizing the experimental data two appropriate functions for these two material parameters were obtained and incorporated into the life prediction equation. Fatigue life predictions using this method have been found to be within 10 percent of the experimental values. [S0094-4289(00)02404-X]