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Center for Nonlinear Studies |
A reliable performance of materials in various environments requires a fundamental understanding of the role and contribution of the various processes occurring at the atomic scales and their contribution to the behavior at the macroscopic scales. Computer simulations allow the study of these phenomena and can complement experiments in the design of new materials with superior properties. My talk will discuss the capability of classical molecular dynamics (MD) simulations to model the microstructural evolution of materials in various environments. In particular, the deformation and failure behavior of metals under shock loading conditions as well as melting and recrystallization behavior of covalently bonded materials will be discussed. The predictive capability of MD simulations, however, is limited by the critical challenge attributed to the time and length scales accessible for the simulation. To address this challenge, a computationally efficient mesoscale modeling method called “quasi-coarse-grained dynamics” (QCGD) is developed that extends the time and length scale capabilities of MD simulations to the mesoscales. The QCGD method is based on solving the equations of motion for a chosen set of representative atoms (R-atoms) from an atomistic microstructure and retaining the energetics of these atoms using scaling relationships for atomic scale interatomic potentials as would be predicted in MD simulations. The success of the QCGD method is demonstrated by reproducing the thermodynamic behavior and the mechanical behavior of FCC, BCC, HCP and diamond cubic systems as observed using MD simulations using a reduced number of atoms and improved time-steps. The capability of the QCGD simulations to model the shock response and failure behavior of metals and unravel the evolution of microstructure at the mesoscales will be discussed.
Host: Avadh Saxena