Influence of the edge effects on the initial velocity of fragments from a warhead

Warhead explosion computer simulations were carried out using the Hemp code, a two dimensional finite difference model. Several parameters were studied, including length to diameter ratio, metal/explosive weight ratio and the weight of closures. Each simulation provided information on isochrones, velocity of casing points versus radial displacement and the distribution of velocities along a warhead generatrix at casing rupture. A comparison with experimental results is given. The model predicts accurately the distribution of velocities of the fragments from a cylindrical warhead. An improvement of the Randers-Pherson model is proposed, as well as a further application to a warhead having closing plates at the ends.