FATIGUE BEHAVIOR OF RESIN INFUSION PROCESSED S2-GLASS WOVEN COMPOSITES

Woven composites have good properties in mutually orthogonal directions, more balanced properties than unidirectional laminates and have better impact resistance. The use of these composites for primary structural applications in place of conventional laminated composites has been increased considerably in the recent years. They are being manufactured by using new processes such as Resin Infusion (RI) and Resin Transfer Molding (RTM). These new processes are low cost, affordable and suitable for high volume manufacturing environment. One of the popular woven composites is fabricated using S2-Glass and C-50 resin system components by using Resin Infusion (RI) and Resin Transfer Molding (RTM) process. These woven composites are being evaluated for Integral Armor applications. These components are expected to be under fatigue loading. To assess the feasibility of this material manufactured through Resin Infusion (RI) and Resin Transfer Molding (RTM), it is very important to understand the fatigue behavior of these composite materials. In the first phase of the study the panels of this material were fabricated using Resin Infusion (RI) processing. Number of tests were performed to evaluate the basic properties such as modulus, ultimate tensile strength, and Poisson's ratio of this woven composite. Tension-tension fatigue experiments with R ratio of 0.1 were conducted to generate two important curves to characterize the fatigue behavior of this material system: S-N diagram and stiffness degradation over the entire fatigue life of the specimens. All the fatigue tests were performed at 1 Hz frequency. To study the progressive damage of the textile composites under fatigue loading. one set of specimens was subjected to different number of fatigue cycles starting from 1 cycle to 300,000 cycles and was investigated for failure mechanism using optical microscopy and SEM.