Multi-scale Modeling and Simulation of High Explosives and Propellants

Science & Technology Review Article March 2003

High explosives (HE) react exothermally when subjected to mechanical insults, including impact and shock, or thermal insults, including both rapid and slow heating. The violence of the response depends on details of the insult, the strength of confinement, and the explosive formulation. Our activities in this area are closely coupled to the Chemical Sciences Division of the CMLS directorate and the Energetic Materials Center.

Our molecular dynamics calculations include classical force fields for the study of shear deformation in explosive molecular crystals and carbon clustering in the gas products of under-oxidized explosives, quantum chemistry simulations to determine decomposition rates of explosives at high temperature and pressure, such as occur in detonations, and the early stages of carbon clustering, and first-principles quantum calculations to examine energy barriers to decomposition pathways.

We use thermochemical equilibrium calculations to predict the high-pressure and high-temperature equation of state of detonation products, including estimates of the transport properties of these fluid mixtures. These properties are used in our coupled thermodynamics-hydrodynamics calculations of high-pressure flame and detonation wave propagation. The results of these calculations of flame speed as a function of pressure and temperature are used in our mesoscale calculations of the transformation of defects into hot spots that release energy by high-pressure flame propagation.

Our simulations are constrained by quasi-static and dynamic experiments performed by other H-Division groups (High Pressure Physics and Shock Physics) as well as others in the CMLS directorate (Chemical Sciences Division).

Our work is used to provide improved predictions of the performance, safety, and reliability of HE, as well as gun and rocket propellants in the nuclear weapons stockpile and conventional weapons systems of the Department of Defense.

For more information on this project, please contact Jack Reaugh.

UCRL-MI-142025