Short Pulse Initiation of an RDX‐Based Explosive Using Large Diameter Flyer‐Plate Impacts

Abstract

AbstractTen impact experiments are presented that probe the initiation behavior of an RDX‐based explosive. The explosive pellets were impacted by thin aluminum impactors supported by low‐impedance polymers, thereby subjecting the pellets to short duration shocks. Impact conditions were used to determine impact tilt, pulse pressure and duration, sample transit time, and whether or not a detonation occurred. Exploding Foil Initiator (EFI) launchers were used as a baseline for evaluating the technique, and it was found that the present technique addresses multiple shortcomings of EFI‐based systems. The aluminum foil allowed impacts with pressure durations of 70–80 ns, resulting in input conditions closely matching those of EFI‐based systems. The thicker aluminum plate impactors resulted in pulse durations of approximately 600 ns and allowed access to a previously inaccessible region of the initiation curve. Initiation thresholds were bracketed using both impactors, and the data is compared with complementary initiation data from EFI‐based systems with good agreement. Based on the results and closely related work, a novel, physically‐based criterion is proposed to allow the initiation curve to be predicted based on the explosive's unreacted equation of state and sustained‐pulse, shock‐to‐detonation run distance (the “Pop‐plot”), giving a physical basis for previously published observations. Finally, the criterion is applied to the data available to propose a relationship between pressure, pulse duration, and run distance, suggesting that input pulse durations of 50–100 % higher than the critical condition should be applied to approximate the run distance of a sustained pulse.