Wide-Temperature-Range Large-Deformation Tensile Behavior and Constitutive Modeling of Polytetrafluoroethylene

This study investigates the tensile behavior of polytetrafluoroethylene (PTFE) tube material across a wide range of temperatures, displacement rates, and sampling directions. Temperature has a dominant effect: flow stress decreases and ductility increase markedly as temperature rises, while displacement rate and sampling direction show only minor effects. A temperature-coupled three-part superposition quasi-static stress (TPS) model is developed, using Arrhenius-type relationships to describe how the model parameters evolve with temperature. This model outperforms the Johnson–Cook, Ogden, and Zhu–Wang–Tang (ZWT) models across the full strain range and the entire tested temperature range. Molecular dynamics simulations further show that rising temperature increases free volume and chain-segment mobility while reducing chain orientation, providing a molecular-scale explanation for the observed thermal softening.