Thermo-visco-plastic behaviour of fibre-reinforced polymer composites

The effect of temperature and strain rate on the tensile behaviour on a series of polymeric matrix-unidirectional glass–fibre composites was studied. Dynamic mechanical analysis (DMA) experiments, as well as tensile tests at three different strain rates and three different temperatures below Tg were performed on off-axis specimens of three different orientations. The strong temperature and strain rate dependence, exhibited by the materials examined, was further described theoretically by applying a formulation of finite elastoplasticity. Constitutive laws based on the material anisotropy, were applied, in combination with constitutive equations of hypoelasticity, written in their objective form. Moreover, empirical equations for the hardening coefficients, arising from the thermal activation theory, were proposed to formulate the temperature and strain rate effect.