Cookoff of Black Powder and Smokeless Powder

Abstract

We have completed a series of both vented and sealed cookoff experiments of black powder and smokeless powder in our Sandia Instrumented Thermal Ignition (SITI) apparatus at bulk densities of 1078 and 729 kg/m3, respectively. The confining aluminum cylinder was ramped from room temperature to a set point temperature and then held at the setpoint temperature until ignition. The setpoint temperatures varied between 495 to 523 K for the black powder and 401 to 412 K for the more sensitive smokeless powder. The vented experiments show a significant delay in thermal ignition, indicating that the ignition is dependent on pressure. Post experimental debris shows greater violence for our smokeless powder experiments than our black powder experiments. A simplified universal cookoff model (UCM) was calibrated using the black powder and smokeless powder SITI data and used to predict pressurization and thermal ignition. The current work presents the first calibration of the UCM with a double base propellant. This work also presents the first pressure‐dependent cookoff model for black powder and smokeless powder.

A Micromechanics Pressurization Model for Cookoff

“…A single high-density Sandia Instrumented Thermal Ignition (SITI) experiment [22] shown in Figure 5(a) is modeled in this section. Details of the SITI experiment have been described in numerous publications, e. g. [6][7][8][9][10][11][12][13]. The SITI experiment consists of two 2.54 cm diameters by 1.27 cm high cylinders of high-density PBX at 1881 kg/m 3 confined in the center of a 7.62 cm diameter aluminum cylinder.…”

“…Pressurization models in previous work [6][7][8][9][10][11][12][13] did not account for volumetric strain explicitly in the formulation, which could result in excessive pore crush for high-density formulations leading to negative gas volumes where the pore volume inverts leading to a non-physical solution and code stability issues. Pore volume inversion has not been a problem for low-density and intermediate-density explosives with large ullage volumes, pore volume inversion has been problematic for pressed explosives that are near the theoretical maximum density (TMD), such as the TATBbased explosive shown in Figure 1.…”

Cookoff of Powdered and Pressed Explosives Using a Micromechanics Pressurization Model

“…The Sandia Instrumented Thermal Ignition (SITI) experiment has been used to measure thermal ignition in a variety of explosives such as AN (ammonium nitrate) [13], TNT (trinitrotoluene) [14], PETN (pentaerythritol tetranitrate) [15], HMX (octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazoncine) based explosives [16,17], RDX (hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine) based explosives [18], Comp‐B (60 : 40 RDX : TNT) [19], ϵ‐CL‐20 (2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane) [20], black powder and smokeless powders [21]. We have used many varieties of the SITI experiment with various ullage and explosive volumes.…”

“…(2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) [20], black powder and smokeless powders [21]. We have used many varieties of the SITI experiment with various ullage and explosive volumes.…”

Waste Control Specialists Technical Review Team Report

“…Pressure, from evolution of gaseous products, is determined using a gas equation of state with an analytical expression for deformation of spherical defects caused by internal gas generation balanced by material strength in both gas permeable and impermeable waste. This model approach is robust and has been used for a wide range of materials from the older explosives [13] to newer explosives [14].…”