Multiscale micromorphic theory compatible with MD simulations in both time-scale and length-scale

Abstract

In this study, the two-scale micromorphic theory incorporating tensile experiments and molecular dynamics (MD) simulations, which are compatible in both length scale and time scale is investigated. To the authors’ knowledge, this is the first attempt to combine fully-compatible experiments and MD simulations into a multi-scale continuum framework while considering the inhomogeneous plastic deformation scheme of glassy polymers. In the two-scale micromorphic model, experimental values are applied to the macro-scale while MD results are applied to the micro-scale. By adjusting characteristic length parameters, we show that the length scale in the continuum formulation can be compatible with that of MD simulations. Moreover, we prove that the micromorphic model can also be compatible in time scale with MD simulations by showing that the micro-scale can reach super-fast strain rates close to MD strain rates. Finally, this model successfully predicts the macroscopic behavior of ductile and brittle deformation when MD results of ductile and brittle cases are assigned respectively to the micro-scale of the micromorphic model. We expect this approach will be a new and essential route for bridging the molecular scheme in MD simulations with the continuum level.