Interactions of impact shock waves in a thin-walled explosive container. I. Impact by a flat-ended projectile

Interaction of impact shock waves that could detonate an explosive (Composition B) confined in a thin-walled container impacted by a cylindrical projectile is numerically studied, based on the Forest Fire explosive reaction rate model. After the impact, rarefaction waves from projectile periphery and front cover–explosive interface catch up the forward-moving shock fronts in the explosive as well as in the projectile. At a high impact velocity, the transmitted shock front induces detonation at the front cover–explosive interface. At an intermediate velocity, the rate of energy release from the shock-compressed volume in the explosive is such that the associated effects prevail over the effects caused by rarefaction waves, leading to detonation after the shock wave travels a certain distance in the explosive. There is a range of minimum impact velocities at which the effect of rarefaction waves prevails over the energy release; hence, the detonation is excited not behind the shock-wave front moving over the explosive but only after shock-wave reflection from the high-impedance back plate. It is suggested that, in interpreting the detonation behavior of an explosive confined by a high-impedance container, one should take into account the effects of shock-wave interaction with container walls.