Experimental and numerical study on the effectiveness of the barrier protecting explosive against electric initiation systems

Improvised explosive devices are responsible for death and injury of thousands of people (both civilians and soldiers) annually. They are often produced by simple home-made modifications of the old artillery shells. One of the ways of preventing modification of currently used artillery shells intended to make it more difficult to use as IEDs was analyzed in the article. A special safety barrier placed between the fuse and the explosive in order to block the access to the explosive after unscrewing the fuse was proposed. The barrier was used also to protect explosive against detonation with commonly used electric initiation systems. Therefore the main aim of the analyses presented in the article was to determine a critical barrier thickness for which the acceptor has 50% probability of being detonated. The research included experimental gap-tests as well as numerical reproduction of the phenomenon in the Impetus AFEA software. Various types of electric initiation systems were analyzed differing with material of the body, type and amount of explosive used as well as the shape of the frontal part of the detonator (flat or with hemispherical cavity). Critical barrier thicknesses were determined for individual variants of donor-gap-acceptor systems. Numerical model of the phenomenon was defined and validated against experimental data. Small differences between the experimental and numerical results allow to use the model to initial evaluation of the effectiveness of different barrier variants.