Effective constitutive equations for fiber-reinforced viscoplastic composites exhibiting anisotropic hardening

Effective elastic-viscoplastic stress-strain relations are derived for fiber-reinforced composites whose constituents are elastic-viscoplastic materials displaying anisotropic hardening. The derivation is based on a recently developed high-order continuum theory with microstructure for the modeling of viscoplastic composites, and is generalized here to incorporate anisotropic hardening effects. A specific reduction of the theory gives the effective rate-dependent elastic-plastic behavior of the composite which exhibits plastic anisotropy. In the special case of perfectly elastic constituents, the approximate overall moduli of the fiber-reinforced composite are obtained. Rate-dependent average stress-strain curves are given for numerous modes of cyclic loading of the composite. The effective behavior of periodically bilaminated viscoplastic composites is determined as a special case.