Study on the Influence of Elongation Ratio on Penetration Depth of Extended Long-Rod Projectiles

To study the effect of elongation ratio μ on the penetration depth of extendable long-rod projectiles (ELRPs), an ELRP was designed based on a conventional homogeneous long-rod projectile. First, finite element software LS-DYNA was employed to simulate the vertical penetration of both projectiles into armor steel targets, with simulation parameters and algorithms validated via experiments; subsequently, systematic numerical simulations analyzed the penetration performance of ELRPs (elongation ratio μ: 5.88–35.00%) under typical artillery velocities (1160–1600 m · s−1) and clarified the mechanisms of penetration depth gain. Results show that under the same conditions, ELRPs outperform homogeneous rods in penetration capability, attributed to two factors: (1) the ELRP’s segmented rod-like penetration mode yields higher efficiency and cumulative damage; (2) the slender leading section of the rear core sharpens the head shape, reducing penetration resistance on the rear core’s main segment to improve performance. However, as the elongation ratio μ increases, the “target core effect” becomes more prominent, weakening the rear core’s penetration. Within the studied range, an optimal elongation ratio μ exists—at 29.00%, the maximum penetration depth gain reaches 18.00%—driven by the competition between the rear core’s penetration enhancement and the target core’s weakening effect.