Cyclic deformation behavior of an epoxy polymer. Part II: predictions of viscoelastic constitutive models

The experimental results presented in Part I of this study were used to evaluate the predictive capabilities of two viscoelastic constitutive models. One of the models, developed by Xia and Ellyin, is in a differential form. The other, which is a modified Schapery model by Lai and Bakker, is in an integral form. The results of the comparison indicate that the Xia-Ellyin constitutive model simulated the experimental observations well. This was attributed to the existence of a general rule that delineates the loading and unloading parts of the cyclic response. The modified Schapery model was able to predict the general trends of the deformation behavior; however, it was unable to correctly simulate the unloading behavior. This difference became more pronounced when the applied cyclic stress/strain was high. At high applied loads, the material response became more nonlinear. POLYM. ENG. SCI., 45:103-113, 2005. [c] 2004 Society of Plastics Engineers
INTRODUCTION Polymers and polymeric composites in engineering service are usually subjected to multiaxial stress states with complex loading histories, and in many cases, the loading is of a cyclic nature. [...]