Stress relaxation properties of an epoxy-based shape-memory polymer considering temperature influence: experimental investigation and constitutive modeling

Abstract

Epoxy-based shape-memory polymer (ESMP), belonging to viscoelastic thermosets, exhibits strong temperature-dependent relaxation property caused by the glass transition process. Thoroughly experimental investigation and accurate numerical prediction are indispensable to be performed in the structures that demand for high precise structural controls. In this work, key parameters of an ESMP in stress relaxation process including initial modulus, elastic modulus, viscous modulus and relaxation time were experimentally investigated and constitutive-model-based analyzed to study the influence of the temperature, where the constitutive model was established by modifying the constant parameters of a neo-Hookean hyper-viscoelastic model to be functions of the temperature. A numerical simulation method was developed by coding UMAT in ABAQUS using the constitutive model and was verified by finite element simulations of stress relaxation experiments. The maximum deviation of 4.5% between simulations and experiments indicated the reasonability of the model in depicting stress relaxation process considering the influence of the temperature.