Atomistic modelling of the hypervelocity dynamics of shock-compressed graphite and impacted graphene armours

S Signetti and K Kang and NM Pugno and S Ryu, COMPUTATIONAL MATERIALS SCIENCE, 170, UNSP 109152 (2019).

DOI: 10.1016/j.commatsci.2019.109152

We present a molecular dynamics (MD) simulation study on the hypervelocity dynamics of shock compressed graphite-up to hundreds of gigapascals- and impacted multilayer graphene armours by employing the AIREBO-M potential. The Morse-type non-singular intermolecular interaction allows the usage of relatively large integration timesteps for simulating materials' response at such high strain-rate. The MD simulation results are in good agreement with the shock Hugoniot curves and with graphite-to-diamond transition obtained from both density functional theory (DFT) and experiments available in literature. We then show that thermodynamic properties of graphite from MD calculations can be used as input for a reliable equation of state to be employed in continuum simulations. Finally, we find that the size-scaling of the hypervelocity impact properties of graphene armours matches well with the DFT results and theoretical predictions of earlier studies. Our results open a concrete possibility towards accurate and fast multiscale simulation from atomistic to continuum level of shock propagation, shock-induced phase transformation, and dynamic fracture in large or hierarchical carbon systems, such as graphene-based foams and nanocomposites.

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