A micromechanical approach to the viscoelasticity of unidirectional hybrid composites

Combination of the well-known rule of mixts. and the classical theory of linear viscoelasticity leads to a stress/strain relation that effectively predicts the viscoelastic behavior of hybrid composites in uniaxial extension. From this theory, the rule of mixts. does not apply directly to the dynamic quantities, whereas it can be used directly to correlate the storage and loss moduli of the composite to the properties of its components. The stress/strain relation is exptl. verified under isothermal conditions for a unidirectional, hybrid polyethylene-aramid/epoxy system both in const. strain rate and dynamic forced vibration expts. The micromech. model leads to numerical predictions which are in good agreement with exptl. data on composite materials in various compns.