Velocity of detonation,charge diameter and critical diameter in unconfined RDX-driven heterogeneous explosives

Abstract

The relationship between the experimentally-determined velocity of detonation of unconfined, cylindrical charges of RDX-driven PBXs and composite explosives, V(d), and charge diameter, d, has been examined critically. It has been found that, for many formulations, the data can be fitted more satisfactorily to an elliptical relationship between V(d) and (1/d) than to a linear relationship but this depends, at least in part, on the particle size distribution and shape of the RDX used in the formulation. It has also been observed that the experimentally-determined critical diameter of the formulation, d_c, can be directly related to the linear coefficient in the elliptical V(d) / d relationship, a*, by the equation, d_c = 2.208 a*. This leads to a practical outcome, namely:- that the critical diameter of an explosive formulation may be estimated without the need to prepare a large number of charges, very close to or less than the expected d_c.