Numerical procedure for the prediction of projectile residual velocity for impact on mild steel plates

Abstract
The present paper deals with the development of a numerical procedure for the prediction of residual velocities of hard core ogival-nose projectiles normally impacting on mild steel target plates. The finite element modelling criteria are arrived at through a mesh convergence study by successively refining shell elements used for representing target plates. For generality, jacketed projectiles with a copper sheath and a hardened steel core are modelled with solid elements. The simulations are carried out with the explicit contact-impact LS-DYNA solver by employing a tabular strain rate-dependent constitutive model for the target plate. It is shown that the proper choice of mesh density is crucial for obtaining test-compatible residual velocity. The present approach of material modelling which captures the effects of strain rates on yield and failure stresses as well as failure strain is compared against strain rate-dependent modelling using the well-known Cowper-Symond relation. It is shown that the predictions using two different material models are found to be very similar to each other for the same target material. Additionally, the benchmarked modelling procedure is applied to computation of ballistic limits and studying the effect of plate thickness on projectile residual velocity.