Publications Details

Effects of Microstructure and Surface Roughness on Initiation Behavior in Vapor-Deposited Explosives

Stewart, James A.; Monti, Joseph M.; Bassett, William P.; Knepper, Robert A.; Damm, David L.

A mesoscale model for the shock initiation of pentaerythritol tetranitrate (PETN) films has been utilized to elucidate changes in initiation thresholds due to aging conditions and surface roughness, as has been observed from a series of high-throughput initiation (HTI) experiments. The HTI experiment has generated a wealth of thin-pulse, sub-millimeter shock initiation data for vapor deposited PETN films with thicknesses of 67-125 μm and varying accelerated aging conditions. This is because the HTI experiment provides access to growth-to-detonation information for explosives that exhibit a shock-to-detonation transition (SDT) with length and time scales that are too short to be resolved by conventional experiments. Mesoscale modeling results using experimentally characterized PETN microstructures are able to capture the general trend observed in experiments, in that increasing flyer impact velocity increases reactions until full detonation is reached. Moreover, the varying degrees of surface roughness that were considered were found to provide only minor variances in the peak particle velocity at the explosive output. The model did not predict a shift in the initiation threshold due to aged microstructures alone, indicating that additional mesoscale model improvements are necessary.