Numerical Investigation of Penetration Characteristics of Preformed Spherical Fragments at Hyper Velocity

Abstract

Numerical investigation of penetration characteristics of 6mm SS304 preformed spherical fragments released from a Fragment Generator Warhead (FGW) impacting on Steel 1006 target plate of 1 mm, 3 mm and 6 mm thick in velocity range 1000 m/s to 5000 m/s and impact angle between 0° and 75°, has been carried out using the explicit code LS-Dyna which is predominantly used for solving impact problems. The simulation model employs a strain rate dependent plasticity model viz. Johnson-Cook model supplemented by Gruneisen Equation of State (EoS), to capture the large strain encountered in target plate due to impact of a spherical fragment at high velocities. The simulation model results are presented in terms of crater diameter on the target plate normalised over original fragment diameter. Empirical equations are available in literature to estimate the normalised crater diameter under the same impact conditions employed in simulation models. The simulation model results have been validated with experimental data available in literature and also found to be in good agreement with the results obtained from empirical equations. The effectiveness of the erosion contact algorithm over Smoothed Particle Hydrodynamics (SPH) method in LS-Dyna to reasonably predict the behaviour of the target material at high velocities of impact is demonstrated in the current study.