Planar Shock Initiation of Porous Tetryl

Abstract

The plane‐wave shock initiation of a large particle size tetryl has been studied at five pressing densities between 1.30 and 1.70 g/cc. The explosive wedge technique was used to observe shock buildup to detonation for a number of initial shock strengths, obtaining shock position data as a function of time. Single‐curve buildup was assumed to determine values of the initial shock velocity in the explosive and these were used in the impedance‐match solution to compute the initial shock parameters in the explosive. Quantitative expression of the measured time of shock run in terms of the computed shock strength leads to a set of initiation relations characteristic of the test explosive. Comparison of these initiation curves for different densities of tetryl suggests that at least two initiation mechanisms are effective in low‐density tetryl. This interpretation is illustrated by discussing the data in terms of two theories of initiation which have appeared in the literature.