Anisotropic effects in large pore collapse and hot spots: continuum and molecular scale shock simulations

The formation and growth of hot spots has been shown as a driving mechanism for initiation in energetic materials. Many of these hot spots form due to shocks interacting with defects within the microstructure, such as pores and cracks. Realistic pore sizes can range from nm to mm, however due to computational costs, most molecular dynamics (MD) studies only simulate O(nm) sized pores. In this work, we use newly developed MD-informed material models [1] to perform continuum-scale pore collapse simulations using pore diameters of 250 nm and 500 nm. The results are compared with identical MD simulations and smaller pore calculations (continuum and MD) to determine any size-dependent effects on pore collapse and hot spots. Notable differences in post-shock shear banding behavior led to further analysis of the molecular simulations by analyzing under which crystallographic orientations shear banding will occur. The P2 order parameters and wag angles were calculated and compared for two different orientations (100) and (110). This work will give insights on pore collapse dynamics and hot spots in large pores along with the apparent anisotropy present during shock passage.



1. Herrin, J., et al., Pore collapse, shear bands, and hotspots using atomistics-consistent continuum models for RDX (1,3,5-trinitro-1,3,5-triazinane): Comparison with molecular dynamics calculations.Journal of Applied Physics, 2024. 136(13).