Effect of Casing Material on performance of Cased Munitions

Abstract

Prediction of blast parameters for cased munitions always remains prime interest for explosive experts and researchers in the field of energetic materials. These parameters not only assist us in characterization of warhead (warhead design and safety analysis) but are also the direct measure of performance/efficiency of warhead. These blast parameters include initial fragments velocity of fragments, shock wave pressure, number/size of fragments produced and spatial distribution of fragments. Determination of these parameters is a challenging task due to high cost of arena testing (acquisition of firing range and precise equipment like high speed cameras to measure fragments velocities), adhering to the safeties involve in handling of explosives, time and lot of manpower/other resources. Alternatively, numerical simulation techniques can be used to model the blast/fragmentation behavior of cased munitions. Besides providing better understanding of blast/fragmentation phenomena, these softwares can estimate blast parameters of fragmenting warheads. In this study, Autodyn with SPH (Smoothed Particle Hydrodynamics) solver is used to predict the blast parameters of a thick walled cylinder filled with Composition B explosives. Multiple simulations have been carried out by varying casing materials for same warhead. Comparative analysis of different casing materials has been carried on basis of predicted blast parameters of fragmenting warheads. On basis of simulation results, cast ductile iron has been recommended as an alternative casing material to conventional steel casing on basis of its better fragmentation characteristics, high end performance (higher strength, superior shock absorption, corrosion/abrasion resistance etc.) and cost effectiveness. It has been concluded that the casing material also affects the performance of fragmented warheads vis-à-vis efficiency of cased munitions.