Temperature-accelerated molecular dynamics simulations of quasi-static yield stress of epoxy polymers

Abstract

Quasi-static yield stress of epoxy polymers is predicted through the molecular dynamics simulations using temperature-accelerated molecular dynamics approach. The derivation of stress under the quasi-static strain rate has been considered challenging due to the computational inefficiency on the time integral of Newton’s equation of motion. To overcome this time scale limitation, we propose an acceleration approach to construct Eyring’s curve, which can shows rate effect on the stress from quasi-static to high strain rate conditions, using yield stresses of elevated temperature conditions. From the uniaxial deformation simulations, it is found that the derived yield behaviors are highly dependent on the change of temperature and strain rate; the yield stress decreases with decreasing strain rate and increasing temperature. In this study, changeable shifting factors are introduced to appropriately shift the yields of elevated temperature conditions toward the quasi-static rate range. The predicted quasi-static yield stress of epoxy polymers is validated via experimental result. © 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.