Effect of fiber properties on plastic behavior of 2 × 2 biaxial braided composites

Plasticity induced non-linear behavior of 2 × 2 braided composites was analyzed using a two scale modeling approach based on Hill’s yield function for orthotropic materials. Two ±25° biaxial braided composites that used same resin (EPON 9504) but different fibers (AS4 carbon and E-glass) were analyzed under uniaxial tensile loading. The resin was chosen to be the same so that the effect of fiber type on the degree of plasticity induced non-linearity could be characterized. Characteristics such as macroscopic stress–strain behavior, stress distributions, and plastic zone locations and sizes were examined. Conclusions about the effect of fiber type on the degree of plasticity induced non-linearity depend on the parameters chosen to quantify the plasticity. The results suggest that a glass braid tow is probably more susceptible to initiation of fatigue damage than a carbon braid tow of a geometrically similar braid.