Spread of Detonation in High Explosives

Abstract

In a note¹ on the spread of detonation in a mass of high explosive from the point of initiation, Weibull demonstrates that, in a cylindrical cartridge of compressed T.N.T., detonation is propagated with a uniform and constant speed in all directions from the detonator. It may be of interest to record that pressed T.N.T. is not unique in this respect and that other high explosives, under suitable conditions, behave in a like manner. Nevertheless, as has already been shown², a constant rate of detonation from the point of initiation is not a feature common to all high explosives. This is further illustrated in Fig. 1, which is a conventional photograph of detonation traversing a 1¼ in. diameter cartridge of granular T.N.T. cartridged at a density of 1·0 gm./c.c. The cartridge was 7 in, long and was initiated with a detonator embedded in the explosive at the end corresponding to the hooked end of the trace. The curvature of the trace shows that the velocity of detonation was still increasing at 4 in. from the end of the detonator. It is interesting to note that this is the same explosive as that used by Weibull, but in a different physical condition, so that the constancy or otherwise of the rate of detonation in the initial stages is not a function of the explosive alone, but also of its physical condition.