Detonation transfer between explosives is most commonly based on shock wave propagation from a donor to an acceptor charge. The propagation of a shock wave between adjustment explosives or between the explosive and the inert material has a complex nature. Different effects, such as rarefaction waves or surface-surface contact may affect shockwave attenuation.
Engineering design often requires incorporating a metal or air gap between donor and acceptor explosive units. The metal casing of standard explosive units, such as detonators or boosters, may influence the detonation transfer process and therefore has to be taken into account when analyzing the probability of detonation transfer. In such cases application of the classic Gap-Test approach, based on a plastic gap between explosives, is not straightforward. Increasing the air or metal gap between explosives may increase fragment size and dispersion cone and in this way increase the probability of detonation transfer. Substituting an air gap with plastic cards may also increase the probability of detonation transfer because of higher impedance values of the media.
A semi-analytical analysis was performed, followed by a series of experiments in which explosive trains with various gap media between the donor and the acceptor were detonated. The test conditions allow the application of complex gaps made of different materials.
A numerical analysis, based on Lee-Tarver model, was performed in order to verify and analyze the experimental results. The outcome of FEM analysis is consistent with empirical data. Influence of tested inert gap materials and its configuration on shock wave behavior was clearly shown.
The result of the analysis and experiments indicate that there is a complex correlation between shock wave detonation transfer and engineering properties of the gap media used. The gap thickness and material have a major influence on two major modes of detonation transfer, shock wave and fragmentation. The present work may serve as a case
