A thermodynamically consistent elastoviscoplastic phase-field framework for structural damage in PTFE

Abstract

Deformation in polymers is highly dependent on molecular structures and motion and relaxation mechanisms, which are highly influenced by temperature and mechanical load history. These features imply that some models can fit for specific classes of polymers and not for others; moreover, these models also include several non-linearities, which turns out to be challenging for computational simulation. This work develops and simulates a thermal-structural phase-field model for the polytetrafluorethylene (PTFE) polymer. The constitutive multimechanism model used considers a non-isothermal non-linear elastoviscoplastic model, able to represent elastic molecular interactions, and viscoplastic flow from polymer segments. Material parameters for complex rheological models are addressed, through a genetic algorithm, to adjust curves from simulated models to stress-strain experiments available in literature. Results of stress-strain curves, followed by rupture, for a temperature ranging from -50° C to 150° C are plotted in comparison with experimental results, presenting a reasonable fit.