  High pressure shear band formation is a critical phenomenon in energetic
materials due to its influence on both mechanical strength and mechanochemical
activation. While shear banding is know to occur in a variety of these
materials, the governing dynamics of the mechanisms is not well defined for
molecular crystals. We conduct molecular dynamics simulations of shock wave
induced shear band formation in the energetic material
1,3,5-trinitroperhydro-1,3,5-triazine (RDX) to assess shear band nucleation
processes. We find, that at high pressures, the initial formation sites for
shear bands 'over-nucleate' and rapidly lower deviatoric stresses prior to
shear band formation and growth. This results in the suppression of plastic
deformation. A local cluster analysis is used to quantify and contrast this
mechanism with a more typical shear banding seen at lower pressures. These
results demonstrate a mechanism that is reversible in nature and that
supersedes shear band formation at increased pressures. We anticipate that
these results will have a broad impact on the modeling and development of high
strain rate application materials such as those for high explosives and
hypersonic systems.
