Effects of tandem and colliding shock waves on the initiation of triaminotrinitrobenzene

Abstract

The shock initiation of the insensitive high-explosive LX-17, which contains 92.5% triaminotrinitrobenzene and 7.5% Kel-F binder, was studied under simulated accident conditions in which two shock waves interact producing locally high pressures and temperatures. Two experimental geometries were studied using embedded manganin pressure gauges to measure the increases in pressure due to exothermic reaction at various locations as functions of time. These pressure histories were compared to ignition and growth reactive flow model calculations to determine whether a second shock compression of reacting LX-17 caused unusually rapid reaction rates and thus more extreme hazards. One experiment used a tandem flyer plate of aluminum and steel separated by a gap to shock the LX-17 charge, allow it to rarify, and then reshock the damaged charge to even higher pressures. These experiments revealed no significant enhancement of the LX-17 reaction rates under this shock, rarefaction, and reshock loading. The second experiment used a grooved flyer plate to produce a subcritical shock wave in LX-17, which then diverged and collided, producing a Mach stem interaction at the charge axis. The threshold conditions under which the Mach stem grew to detonation were measured. The standard LX-17 ignition and growth model yielded excellent agreement with the pressure gauge records in the Mach stem interaction region. The formation of Mach stem interactions by nearly simultaneous multiple high-velocity impacts was identified as a serious shock initiation hazard for heterogeneous solid explosives.