Orthogonal optimization design and experiments on explosively formed projectiles with fins

Abstract

In this study, a polygonal shell is used to produce an explosively formed projectile (EFP) with fins for good flight stability. The forming characteristics of an EFP with fins produced by a polygonal shell are studied numerically using the LS-DYNA 3D finite element code. Orthogonal design method combined with range analysis is applied to optimize the EFP with fins. The orthogonal test schemes are established with 5 levels under plane initiation of 0.2 times the charge diameter and point initiation, respectively. The influence rankings of the EFP length-to-head diameter ratio, compactness, velocity, kinetic energy and length of fin-to-tail radius ratio are determined. Furthermore, the EFPs of the optimized design are tested for forming and recycling. Subsequently, the EFPs recovered from the tests are reconstructed. Finally, an EFP penetration performance test is conducted. When ignoring the influence of EFP initial state on target penetration, Steinberg and Johnson-Cook (J-C) constitutive models are used for the formation and penetration processes, respectively. The results show that the forming effects of EFPs with fins are coupled by the structure of liner, charge arrangement and shell structure. The ranges of the various structural parameters of the EFPs are obtained. The numerical simulation results of EFP with fins designed by orthogonal optimization method are in good agreement with the experimental results. The effectiveness of Steinberg algorithm and J-C algorithm in EFP forming and penetration process is verified.