Design Analysis of Brass Cartridge Case for Water Disruptor Application

Abstract

Brass cartridge cases are being popularly used in various types of ammunition since last 100 years, e.g., armaments of small-arm cartridges, artillery shell, and power cartridges for fighter aircraft. Cartridges are filled with propellants and pyrotechnic composition. With suitable means of ignition, it generates hot gases with pressure and temperature. These gases are utilized to perform certain work on the system. Brass cartridge case for water disruptor applications plays a significant role in destruction of the suspicious objects. Further, it has cumulative consequence to make them non-operational. This paper discusses the design aspects of brass cartridge for disruptor application of suspected improvised explosive devices (IEDs). Performance evaluation of brass cartridge was carried out in closed vessel (CV) using the data acquisition system. Parameters such as maximum pressure and time to reach maximum pressure have been evaluated in this CV. The brass material properties such as tensile strength, percentage elongation, and yield strength were determined using universal testing machine (UTM). In CV test, the cartridge experienced 16.08 MPa. The same cartridge when fired in velocity test rig (VTR) it was subjected to 63 MPa internal pressure. Using the data obtained by above methods, an attempt has been made to determine stress, strain, and deformation of the cartridge case theoretically and numerically using ANSYS software. The results obtained by both the methods were compared. It was seen that the results are in good agreement with each other. It is observed that the percentage error for Von-Mises stresses is 13.2% using numerical and theoretical. The percentage error between numerical and theoretical values of hoop stresses are 11.5% for stress and for strain it is 9.6%. The main objective of this paper is to carry out design and analysis of cartridge case analytically as well as numerically. The results of FE analysis for stress and strain are in good agreement with theoretical calculated results and numerical analysis as percentage error is less than 13. This draws the inference for validating numerical and theoretical results. The novelty in this research work is that the cartridge case is subjected to propellant pressure generated inside the case with pressure of 63 MPa. This pressure is measured using data acquisition system in a specially designed test rig.