A COMPARISON OF COMPOSITE MATERIAL FAILURE UNDER CYCLIC AND BLOCK AMPLITUDE LOADING

Abstract

Military use of glass fiber composites (GFC) is growing due to their advantageous strength-to-weight ratio. Applications of GFC are currently limited by the incomplete understanding of the failure characteristics of composites. A universal failure criteria and predictive fatigue model have been proposed to predict composite failure. The goal of this study was to further validate and refine the predictive failure model. This study subjected notched quasi-isotropic GFC and cross-ply samples to cyclic loading at multiple percentages of their ultimate tensile strength. This testing generated S-N curves for these composites. Further block amplitude cyclic testing of the notched samples was conducted. The results of the cyclic and stepped cyclic testing were then compared to theoretical predictions from the predictive model. GFC offer a variety of benefits over traditionally used materials; a better understanding of the failure criteria will allow these benefits to be applied in more areas of ship and aircraft design.