Nanoindentation of the Triclinic Molecular Crystal 1,3,5-Triamino-2,4,6-trinitrobenzene: A Molecular Dynamics Study
N Mathew and TD Sewell, JOURNAL OF PHYSICAL CHEMISTRY C, 120, 8266-8277 (2016).
Nanoindentation of the insensitive energetic molecular crystal 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) was studied using constant- temperature and constant-energy molecular dynamics simulations. Displacement-controlled indentations at constant velocity were performed using a rigid, spherical indenter on the three principal crystallographic planes, (100), (010), and (001). The force displacement curve for the (001) (basal) plane exhibits a distinct elastic region in agreement with the analytical solution for indentation of an anisotropic half-space by a parabola of revolution. Stiffening precedes inelastic deformation, and the elastic-inelastic transition occurs with kinking and delamination of the layered basal planes and significant pile-up. The predicted nanoindentation hardness on the basal plane is 1.02 +/- 0.09 GPa. Nanoindentation on the (100) and (010) (nonbasal) planes yields a non-Hertzian response; this is attributed to an effective "softening" due to elastic bending of the molecular layers. Significant heating occurs in the vicinity of the indenter during indentation with a higher temperature rise for the basal plane.
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