Predicting the Impulse from the Curved Surface of Detonating Cylindrical Charges

Abstract

AbstractTNT (Trinitrotoluene) equivalency depends on knowing the relative strength of different explosives compared to TNT. However, the current values for TNT equivalency mostly depend on work on spherical charges, whereas most military ammunition is cylindrical in shape. Cylindrical charges are known to give an enhanced blast close in when compared to that of spherical charges. A previous paper looked at predicting the peak pressure perpendicular to the curved side of a cylinder. This paper examines impulse data for the curved surface of cylindrical charges from the literature for Composition B and Pentolite and then describes experimental work carried out on cylindrical PE4 charges. Analysis of the free air experimental and literature data shows that it is possible to predict the impulse using a linear relationship, though it is not possible to decide on the best fit based on the current data. The fits for both I=KIM0.5/R and I=${K{^\prime}_{\rm{I}} }$M2/3/R give very similar correlation coefficients, where M is the charge mass and R the distance from the charge and KI and ${K{^\prime}_{\rm{I}} }$ are constants characteristic of the explosive. Values of KI and ${K{^\prime}_{\rm{I}} }$ have been fitted to literature and current experimental data for Composition B, Pentolite and PE4. Whichever of these two relationships is used, it should be possible to develop a method of determining TNT equivalency for the curved surface of cylindrical charges by using TNT equivalency=KI explosive/KI TNT, provided that data for TNT cylinders is obtained.