Accurate Prediction of Projectile Residual Velocity for Impact on Single and Multi-Layered Steel and Aluminum Plates

The present paper deals with the simulation of impact of jacketed projectiles on thin to moderately thick single and multi-layered metal armor plates using explicit finite element analysis as implemented in LS-DYNA. The evaluation of finite element modeling includes a comprehensive mesh convergence study not previously reported in literature, using both shell and solid elements for representing single-layered mild steel target plates. It is shown that the proper choice of contact algorithm, mesh density, and strain rate-dependent material properties is crucial as these parameters significantly affect the computed residual velocity. The modeling requirements are initially arrived at by correlating against test residual velocities for single-layered mild steel plates of different depths at impact velocities in the range of ~800-870 m/s. The efficacy of correlation is adjudged in terms of a ‘correlation index’, defined in the paper, for which values close to unity are desirable. The experience gained for single-layered plates is next used in simulating projectile impacts on multi-layered mild steel target plates and once again a high degree of correlation with experimental residual velocities is observed. The study is repeated for single- and multi-layered aluminum target plates with a similar level of success in test residual velocity prediction. To the authors’ best knowledge, the present comprehensive study shows in particular for the first time that, with a proper modeling approach, LS-DYNA can be used with a great degree of confidence in designing perforation-resistant multi-layered steel and aluminum armor plates.