Averaging Molecular Dynamics simulations to study the slow-strain rate behavior of metals
Sarthok. K. Baruah Sabyasachi Chatterjee Amit Acharya Gerald J. Wang
The application of molecular dynamics (MD) simulations to quasi-static loading is severely limited by the large separation between atomic vibration timescales and experimentally relevant deformation rates. In this work, we employ the Practical Time Averaging (PTA) framework to overcome this limitation and enable atomistic simulations of crystalline solids under quasi-static loading conditions. PTA exploits the intrinsic separation of time scales by defining slow variables as time-averaged observables of the fast atomistic dynamics and their evolution in the slow loading timescale, thereby avoiding explicit integration of the fast dynamics. Using this approach, we simulate uniaxial deformation, in both tension and compression, of (4 to 20) nanometer sized cubic specimens of face-centered cubic Aluminum nanocrystals and applied strain rates approaching quasi-static conditions (10^−4 s−1 − 10^−3 s−1).
