Mechanism of Hotspot Formation in Energetic Materials Under Mild Impact Loading

Million tons of explosives are used in mining, civil engineering, and military applications. Accidental detonation of these explosives due to mild impact loading during transportation and handling has been a significant concern. These explosions form highly localized temperature regions called ‘hot spots.’ However, the fundamental mechanism of hot spot formation remains elusive. An experimental investigation using ultrahigh-speed microscopy and high-speed visible imaging is performed in this study to reveal the hot-spot generation mechanism under mild impact loading conditions. A model particulate composite, with its constituents, has properties roughly equal to its counterparts in polymer-bonded explosives and is used to reveal the dominant heat-generating deformation mechanisms. The high-speed microscopic infrared full-field measurement of the model material under dynamic loading showed that the local heating is mainly concentrated in the binder solid inclusion interface region. On the other hand, a high spatiotemporal resolution deformation measurement on the model composites reveals that this local heating is mainly due to the sudden frictional relative movement between the inclusion and the binder.