BALLISTIC LIMIT EVALUATION OF A 5 MM STEEL PLATE AGAINST FRAGMENT SIMULATING PROJECTILE USING SINGLE STAGE PROPELLANT GUN

Abstract

Steel Plate is used for protection against fragments in auxiliary units of the armament system. The Ballistic Limit (BL) of the protection plate must be evaluated. This study evaluated a 5 mm steel plate for its BL against a 0.22’ calibre Fragment Simulating Projectile (FSP) using a smooth bore single-stage propellant gun of 30 mm Caliber with the support of Nylon Sabot. The velocity of the fragment was varied by adjusting the charge mass of the propellant (NC 1140) from 18 to 28.75 g to get a velocity from 600 m/s to 933 m/s. IR-based velocity screens were used to measure the projectile striking and residual velocity for pre and post-impact respectively. The target material was 1.0421 ST-52 Grade Steel, which is low-carbon manganese steel with good impact resistance. The projectile material was AISI 4340 Steel of Rockwell Hardness 30 ± 1 HRC. The FSP was recovered and the residual mass of the fragment was measured. It was concluded that there was negligible change in the mass of the recovered fragment. Therefore, the Recht-Ipson (RI) model of ballistic limit estimation is applied to evaluate the Ballistic Limit of the plate. In addition to this, V50 ballistic limit was also computed which is a statistical approach. It is observed that the V50 Ballistic limit for the target-projectile combination is 862 m/s approximately, whereas the RI model predicts a slightly higher ballistic limit.1