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ISSN Druckformat: 2150-766X
ISSN Online: 2150-7678
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NOVEL APPROACH TO MAKE HUGONIOT PREDICTIONS: QUANTUM MECHANICS/MOLECULAR DYNAMICS CALCULATIONS
ABSTRAKT
This paper proposes a novel approach to predict Hugoniot properties to characterize explosives materials. The originality and uniqueness of the approach consists in using together quantum mechanics, molecular dynamics calculations combined with known analytical methods. Indeed, four highly experimentally characterized energetic materials, cyclotrimethylenetrinitramine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), pentaerythritol tetranitrate (PETN) and triaminotrinitrobenzene (TATB), were investigated using quantum mechanics calculations and analytical methods. Using the pressure p and the ratio of specific densities v/v0, the p-v Hugoniot diagrams were obtained. Detonation velocities D were determined and used to define the Raleigh line. For the four compounds, the ratio of specific heats γ, a value between 2 and 3, was obtained. The γ effect, in terms of sensitivity and importance, was demonstrated. At the Chapman−Jouguet (CJ) state, the parameters (shock, particle and detonation velocities, CJ pressure and density, ratio of specific heats, and Hugoniot diagrams) were predicted and all compared quite well with the published experimental data. Moreover, molecular dynamics simulations were carried out to obtain the compression p-v diagrams. Using the isothermal-isobaric ensemble (NPT), molecular dynamics simulations were conducted at various pressures ranging from 2 to 40 GPa with progressive increments of 2 GPa. The Rankine−Hugoniot jump conditions were considered, and the associated shock speed Us and particle velocity up for each pressure p and relative volumetric change v/v0 were calculated. The simulations showed that a linear behavior exists between Us and up for the four explosives investigated.