Prediction of the Full-Scale Cook-off Response Based on Small-Scale Testing

Reducing the violence of Slow Cook-Off (SCO) and Fast Cook-Off (FCO) to acceptable levels is of great interest to the Insensitive Munitions development. For example, the MIL-STD-2105C SCO test for Insensitive Munitions (IM) compliance requires a slow heating rate (3.3°C/hr) until reaction occurs whereby the ensuing reaction is characterized by degree of violence. A Type V (burn) reaction or better is required to pass the SCO IM metric. Latent venting is a common physical approach used to reduce the SCO violence of warheads. BlazeTech has developed a physics-based, fast-running model for the cookoff of munitions. The model describes the thermodynamic, kinetic and physical (such as thermal expansion and increase in porosity/internal surface area) transformations of the explosive prior to ignition and relates them to the increase in burn rate and reaction violence. This model has been partially validated using both SCO and FCO test data on PBXN-109 and PBXN-5. The primary objective of this effort is to tailor the existing BlazeTech cookoff model to PBXN-111 and incorporate the effect of venting on reaction violence. The integrated model can then be used to design a vent that reduces cookoff violence sufficiently to pass the IM metrics.