January 24, 2017 @ 11:00 am - 12:00 pm
Non-equilibrium multi-scale coarse-grained simulation of energetic molecular crystalline materials
Sergey Izvekov, ARL
Energetic materials are often micro-structured crystallites in which mechanical stimulation (e.g., shock or shear) at the mesoscale can incite responses over a wide range of spatial and temporal scales. Computationally-reasonable particle-based simulations of energetic material behavior influenced by structural heterogeneities (from nano- to mesoscales) require implementation of both coarse-grained (CG) models and methodologies. Most CG modeling efforts have focused on predicting equilibrium properties with limited studies attempting to track non-equilibrium processes. In this presentation, a suite of computational tools is described that has been developed to simulate the response of CG models to stimuli, including structural rearrangement, mechanical deformation, phase transitions and chemical reactivity. Approaches have been developed to both generate and parameterize the CG models, as well as to simulate their non-equilibrium behavior based upon the multi-scale coarse-graining (MS-CG) [1-3] and constant-energy dissipative particle dynamics (DPD-E) [4,5] methodologies. The computational framework allows for bottom-up parameterization from higher resolution models for all components, although is not a requirement. The project is motivated by application of these tools to simulate the thermo-mechanical response of microstructurally-heterogeneous solid energetic composites, such as RDX/polymer explosives. However, the framework and methodologies are generally applicable to a wide range of material classes. We report applications of new MS-CG/DPD-E models to study shock propagation and hotspot formation in RDX based explosive. To date, progress has been encouraging, where we find the accurate MS-CG models coupled with the DPD-E method to be a viable tool for simulating the thermo-mechanical response of nanostructured molecular materials to mechanical stimuli.
References:
[1] S. Izvekov and G. A. Voth, J. Chem. Phys. 123, 134105 (2005).
[2] S. Izvekov, P. W. Chung, and B. M. Rice, J. Chem. Phys. 135, 044112 (2011).
[3] S. Izvekov and B. M. Rice, J. Chem. Phys. 140, 104104 (2014).
[4] M. Lísal, J. K. Brennan, and J. Bonet Avalos, J. Chem. Phys., 135, 204105 (2011).
[5] J. K. Brennan, M. Lísal, J. D. Moore, S. Izvekov, I. V. Schweigert, and J. P. Larentzos, J, Phys. Chem. Lett. 5, 2144 (2014).
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