Molecular Dynamics Simulation of Shock Response of CL-20 Co-crystals Containing Void Defects

Abstract

To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane (CL-20) co-crystals, shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene (TNT), 1,3-dinitrobenzene (DNB), solvents ligands dimethyl carbonate (DMC) and gamma-butyrolactone (GBL) with void were simulated, using molecular dynamics method and reactive force field. It is found that the CL-20 co-crystals with void defects will form hot spots when impacted, significantly affecting the decomposition of molecules around the void. The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s, and the main reactions are the formation of dimer and the shedding of nitro groups. The existence of voids reduces the safety of CL-20 co-crystals, which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly. Detonation has occurred under the reflection velocity of 4 km/s, energetic co-crystals are easier to polymerize than solvent co-crystals, and are not obviously affected by voids. The results show that the energy of the wave decreases after sweeping over the void, which reduces the chemical reaction frequency downstream of the void and affects the detonation performance, especially the solvent co-crystals.

Keywords

• CL-20 co-crystals
• Molecular dynamics simulation
• Reactive force field
• Impact response
• Hot spot
• Void defect