On the Validity of Hardy’s Atomistic-Continuum Thermomechanical Theory
Albert To (University of Pittsburgh), Yao Fu (University of Pittsburgh)
From Atomistics to Reality: Spanning Scales in Simulations and Experiments Symposium A
Wed 1:30 - 2:50
CIT 165
This work seeks to establish a high-fidelity atomistic-to-continuum link for non-equilibrium processes by making several modifications to Hardy’s theory. Although Hardy’s thermomechanical quantities were derived analytically to conserve mass, momentum and energy, they have not been rigorously tested and validated numerically in the past. Therefore, the validity of Hardy’s theory has been tested by checking if they are able to conserve mass, momentum and energy numerically in the present work. A few non-equilibrium processes were simulated using molecular dynamics (MD), including Gaussian pulse and shock wave propagation in one-dimensional (1D) and three-dimensional (3D) fcc crystals. Based on the test results, a new normalization rule has been proposed so that the computed thermomechanical quantities can conserve the fundamental properties more accurately. To a large extent, Hardy’s theory has been found to be valid regardless of the width of the localization function, the interatomic potential and crystal structure, with and without ensemble averaging. The results from this work will help 1) inject confidence in employing Hardy’s theory with the proposed modifications to analyze MD simulation results, especially for non-equilibrium thermomechanical processes and 2) pave the way for concurrent atomistic/continuum coupled simulations.