A Simplified Micromechancial Model for Analyzing Viscoelastic–Viscoplastic Response of Unidirectional Fiber Composites
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This study introduces a simplified micromechanical model for analyzing a combined viscoelastic-viscoplastic response of unidirectional fiber reinforced polymer (FRP) composites. The micromechanical model is derived based on a unit-cell model consisting of fiber and matrix subcells. In this micromechanical model, a limited spatial variation of the local field variables in the fiber and matrix subcells is considered in predicting the overall time-dependent response of composites. The constitutive model for the polymer matrix is based on Schapery’s viscoelastic and Perzyna’s viscoplastic models. An incremental stress-strain relation is considered in solving the time-dependent and inelastic response. A linearized prediction and iterative corrector scheme are formulated to minimize errors from the linearization within the incremental stress-strain relation such that both the micromechanical constraints and the nonlinear constitutive equations are satisfied. The goal is to provide the accurate effective stress-strain relations of the composites and the corresponding viscoelastic and viscoplastic deformation in the polymeric matrix. The micromechanical model is verified by comparing the time-dependent response of the glass FRP composites having several off-axis fiber orientations with experimental data available in the literature. © 2012 by ASME.
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