A rate-dependent constitutive model predicting the double yield phenomenon, self-heating and thermal softening in semi-crystalline polymers

The double yield (DY) phenomenon observed in a wide variety of semi-crystalline polymers (SCP) adds difficulties the material characterization. In this paper, constitutive model, termed as explicit polymer (ESCP) is proposed to study DY well rate- and temperature-dependent thermomechanical response below glass transition temperature. underlying kinetics due morphological changes spherulite micro-structure represented by rheological analogue described physically-based amorphous intermolecular resistance rate-independent crystalline interlamellar resistance. Independently-identified viscoelastic network are also implemented complete model description. activation disclosure component depend on saturated state phase. validated against experimental data obtained from different authors for three commonly used SCPs: nylon 101, LDPE PA6. A straightforward parameter identification procedure, requiring minimum number calibration tests, presented illustrate usage. thermomechanical-coupled analyses provide satisfactory predictions using simulated models cylinder compression dogbone tensile tests at rates, where self-heating thermal softening effects naturally captured model.