Fatigue Behavior of Filament Warp Yarns under Cyclic Loads during Weaving Process

Warp yarns in their different applications during weaving processes are often required to support loads, either in a static manner (simple tensile) or in a dynamic one (fatigue). For this reason, the investigation into the variations of the mechanical behavior of warp yarns during weaving condition is important. The purpose of this investigation was to simulate the cyclic loading of weaving process on filament warp yarns and report their fatigue behavior. In this study, the general characterization analysis of three types of the most ordinary filament yarns, polyester, polypropylene and nylon, was performed and then their fatigue behavior was simulated as warp yarns under cyclic loading by using the dynamic mechanical analyzer (DMA 2980). For this simulation, by looking at the conditions of the most common weaving looms, two sets of frequencies as loom speed and two sets of strains as loom geometry were chosen. The relevant variations of the yarn elongation, yarn stress, yarn storage modulus, yarn loss modulus and the damping factor of the yarns were measured and studied. Our test results revealed that the polypropylene yarns had the minimum change in their mechanical behavior and the nylon yarns had the minimum amount of characteristics under different loading conditions. It was found that the resistance of nylon to cyclic loads was higher than polyester and polypropylene. Also, polyester was the weakest yarn because of high change range in its mechanical and physical properties. We also demonstrated that only the polyester yarn revealed immediate failure at 2 % strain.