Predictions of viscoelastic strain rate dependent behavior of fiber-reinforced polymeric composites

A viscoelastic damage model for aligned and 3D randomly oriented discontinuous fiber-reinforced polymeric composites is proposed. The model, which predicts the effective viscoelastic stress-strain behavior of the composites, is based on a combination of the Laplace-transformed superposition principle and the ensemble-averaged micromechanics. The Weibull’s damage function is incorporated into the model for the modeling of the evolution of damaged fibers. An inverse analysis based on experimental data is adopted to simulate the strain rate sensitivity of the model. A series of numerical simulations based on the proposed model are performed to examine the influence of damage parameters, fiber orientations, strain rates, and the aspect ratio of discontinuous fibers on the behavior of the composites. In addition, experimental comparisons are made to illustrate and assess the predictive capability of the proposed model.