Nonlinear numerical predictions of three-dimensional orthogonal woven composite under low-cycle tension using multiscale repeating unit cells

This paper reports the low-cyclic tensile responses of three-dimensional orthogonal woven composites based on the micro/meso-scale repetitive unit cells with elastic/viscoelastic models. The repetitive unit cell models for the resin impregnated fiber tows and the three-dimensional orthogonal woven composites at the fabric microstructure level were established. In the micro/meso-repetitive unit cells model, a nonlinear viscoelastic relationship with switch rule is introduced to characterize the mechanical behavior of the resin for the loading/unloading conditions. The fiber/fiber tows are characterized with linear elastic models. And damage initiation and postdamage constitutive models are also included for matrix/fiber and matrix impregnated fiber tows in the finite element analysis. The fatigue model with the mechanical parameters transferred from micro-scale to meso-scale model is numerically simulated with user-defined material subroutine and incorporated into commercial finite element software ABAQUS/Standard. The calculated results manifest the multiscale fatigue behaviors of three-dimensional orthogonal woven composites, such as the global stiffness degradation, decrease of peak stress, and even local damage behavior. The fatigue behaviors are also verified with the data in experimental and indicated that the model is an efficient strategy to predict the low-cyclic fatigue behaviors of polymer matrix composites.