Effect of shape of explosive charge in failure of rolled homogenous armour plate

Abstract

Land based munitions are used in defence applications for protecting the boarders of the country. Effect of the munition is studied for achieving the desired target damage. These munitions have explosive charges of cylindrical or rectangular bar shape depending on the requirement of lethality and coverage area. The bar munitions have rectangular section explosive charges of 100 mm×50 mm×600 mm length on either side of fuze cavity to cover the tracks. Work has been carried out to evaluate the effectiveness of these charges initiated from one end. The cross section of the charge will change the pressure generated in the near field of explosive charge. Rectangular and ‘V’ shape charges were evaluated keeping the explosive weight constant. The pressure generated in near field of charge has been simulated using Autodyne software. There is an enhancement of 2.4 to 3.5 times in peak over pressure and 2.5 to 4.1 times in impulse at 70 mm from base of section at initiation point and 600 mm away along the length. However, blast pressure cannot be measured in the near field due to limitation of instrumentation. Both type of section of bar charge were experimentally evaluated. Explosive mass of 1.9 kg in each case have been filled in the polycarbonate casing made from rapid prototype technique. The rolled homogenous armour (RHA) plates of 1000 mm × 500 mm × 40 mm were kept on cement blocks and charge was kept in inverted position. The charges were fired and failure of RHA plate on the front and rear side of plate have been observed. In case of V shape charge, cutting has been observed due to shape charge effect of plastic casing on the front side and failure is severe compared to rectangular section on the back side.