Calibration Methods for the Extended Prout-Tompkins Chemical Kinetics Model and Derived Cookoff Parameters for RDX, HMX, LX-10 and PBXN-109

Thermal explosions result when local temperature-dependent heat generation exceeds heat loss via conduction. The temperature dependence of the heat source term is directly related to the material’s chemical kinetics, and hence the chemical kinetics has a direct impact on the thermal explosion times of a material. Much success has been gained in past work to accurately model thermal explosions in various explosives using multi-step Arrhenius chemical kinetics models. However, the generation of these kinetics models is time consuming and complex. Therefore, a methodology has been developed that allows for calibration of a single-reaction global kinetics model using One Dimensional Time to Explosion (ODTX) experimental data, which combines an iterative approach with a steepest descents optimization. This methodology has been applied to calibrate kinetic parameters for the widely-used explosives RDX (1, 3, 5-trinitrohexahydro-striazine), HMX (octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine), LX-10 (95% HMX, 5% Viton binder), and PBXN-109 (64% RDX, 20% Al, 16% binders). The average error between experimental and simulated ODTX and STEX data using this technique is approximately equivalent to that using the traditional multi-step models, and the time required for calibration of the global kinetics model has been reduced from months to hours.