A Multiscale Model for the Quasi-Static Thermo-Plastic Behavior of Highly Cross-Linked Glassy Polymers

Abstract

We present experimentally validated molecular dynamics predictions of the quasi-static yield and postyield behavior for a highly cross-linked epoxy polymer under general stress states and for different temperatures. In addition, a hierarchical multiscale model is presented where the nanoscale simulations obtained from molecular dynamics were homogenized to a continuum thermoplastic constitutive model for the epoxy that can be used to describe the macroscopic behavior of the material. Three major conclusions were achieved: (1) the yield surfaces generated from the nanoscale model for different temperatures agree well with the paraboloid yield criterion, supporting previous macroscopic experimental observations; (2) rescaling of the entire yield surfaces to the quasi-static case is possible by considering Argon’s theoretical predictions for pure compression of the polymer at absolute zero temperature; (3) nanoscale simulations can be used for an experimentally free calibration of macroscopic continuum models, opening new avenues for the design of materials and structures through multiscale simulations that provide structure–property–performance relationships.