Irreversible Deformation Mechanisms for 1,3,5-Triamino-2,4,6-Trinitrobenzene Single Crystal through Molecular Dynamics Simulations
Résumé
The plastic behavior of the insensitive energetic molecular crystal 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is investigated through molecular dynamics simulations. A recent method, built to follow any prescribed deformation path, is used to apply directional shear and compressive deformations to a TATB single crystal, leading to the tridimensional characterization of its nucleation von Mises stresses σv(θ, ϕ), where θ and ϕ are the two angles (latitude and longitude, respectively) that define the loading direction. Furthermore, the local computation of the deformation gradient tensor helps to identify the mechanisms of the irreversible deformation. Two main types of plasticity mechanisms have been identified for the TATB single crystal: First, molecular dynamics simulations predict the existence of dislocations with an unusual local through-plane dilatancy process. Various slip systems among four different nonbasal planes have been identified, namely, (1̅01), (101), (01̅1), and (011) planes. Second, every deformation containing a basal-plane compressive component involves buckling deformation. A deformation path allowing a perfect twinning of the TATB triclinic cell has been found. This structure has been verified through molecular dynamics (MD) simulations. In order to understand the buckling mechanism, the TATB single crystal behavior under compression along its basal plane is studied in detail.
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