Accuracy of Empirical Gurney Velocity Prediction Models

Abstract

Gurney Velocity of an explosive is a required input into the standard Gurney Model of fragment velocity prediction from a metal cased explosive. It is a critical parameter in the comparison of compositions for performance prediction. Eight empirical Gurney theories discussed in this paper enable prediction of the Gurney Velocity of explosive compositions using differing Detonation parameters. Some parameters are easy to access, whilst others can be difficult to obtain. Only empirical methods are assessed here, being both simple to implement, but also giving reasonable accuracy. Aluminised explosive compositions are treated in an identical manner. Two Gurney Velocities exist for each explosive, ‘prompt’ for rapid case fracture and ‘terminal’ for ductile case expansion. This paper considers only the ‘terminal’ value, being the most important. Analysis of the accuracy of each empirical method is given and statistical comparisons made. Surprisingly some complex methods do not necessarily give any more accurate predictions.