Nonlinear viscoelastic behavior of epoxy polymer-experiments and constitutive modeling

摘要

A systematic experimental investigation of an epoxy polymer has been carried out using thin-walled cylindrical specimens. The results clearly indicate a nonlinear viscoelastic behavior of the epoxy polymer with time- and path-dependency, interaction between shear and normal stresses, and the hydrostatic stress influence. A recently developed constitutive model is used to predict these experimental observations. The predictions for the creep-recovery and the transient loading-unloading tests are in good agreement with the experimental results. The hydrostatic stress effect is considered in the model formulation through introduction of a modified equivalent stress. In the case of complex biaxial loading, the model predicts the observed experimental trends in a qualitative sense, and the quantitative agreement is not as good as that of simple loading cases.