William Georges

The effect of detonation wave incidence angle on the acceleration of flyers by explosives heavily laden with inert additives

The incidence angle of a detonation wave in a conventional high explosive influences the acceleration and terminal velocity of a metal flyer by increasing the magnitude of the material velocity imparted by the transmitted shock wave as the detonation is tilted towards normal loading. For non-ideal explosives heavily loaded with inert additives, the detonation velocity is typically subsonic relative to the flyer sound speed, leading to shockless accelerations when the detonation is grazing. Further, in a grazing detonation the particles are initially accelerated in the direction of the detonation and only gain velocity normal to the initial orientation of the flyer at later times due to aerodynamic drag as the detonation products expand. If the detonation wave in a non-ideal explosive instead strikes the flyer at normal incidence, a shock is transmitted into the flyer and the first interaction between the particle additives and the flyer occurs due to the imparted material velocity from the passage of the ...

Reduction of ejecta from asperities on a metal surface upon shock breakout

Ejecta can be produced when a shock breaks out of a metallic surface with imperfections. The amount of material ejected depends on the wave profile and the surface finish. This work focuses on techniques to reduce the amount of ejecta produced. As a baseline, a Taylor wave loading was produced by detonating a high explosive next to an aluminum target featuring V-grooves on the free surface. The ejecta and free surface velocities were monitored with photonic doppler velocimetry (PDV). In an attempt to suppress the ejecta, the shock pressure was reduced by the addition of an air gap. The effect of a vacuum gap was also investigated. PDV spectrograms show that significant ejecta traveling at roughly three times the free surface velocity was produced when explosives were in contact with the target. The placement of an air gap or a vacuum gap between explosive and target suppressed detectable ejecta.

Influence of thick surface coatings on jet formation in flyer plate impacts

The criteria for jetting upon the impact of flyer plates is that an oblique shock solution in the impact point reference frame does not exist. This criterion has been extensively verified experimentally over the last few decades. Comparatively, there has been no studies in the open literature regarding the jetting criterion for the impact of multi-layered flyers or flyer plates featuring thick coatings. In this work we have developed an experimental set-up that allowed us to determine whether or not the impact of multi-layered flyers resulted in a jet or not using laser heterodyne velocimetry.