Introduction Penetrator with Enhanced Lateral Effect PELE
Introduction Penetrator with Enhanced Lateral Effect (PELE) is a kind of ammunition which consists of a low-density material as the filling and a high-density material as the jacket [1,2]. When PELE impact target, the jacket is radially accelerated, expanded and fractured because of distinctive lateral effect. Behind-armor fragments by PELE will scatter with higher radial velocity than that by other ammunition such as kinetic PD123319 metal penetrators. This higher radial velocity of fragments will result in enhanced behind-armor damage effect. Paulus and Schirm  conducted PELE experiments by small-caliber projectiles with polyethylene (PE)/aluminum (AG-3) filling and tungsten alloy (D180k) jacket against aluminum (A-U4G)/steel (XC48) target with impact velocity ranging from 900 to 3000 m s−1. Expansion and fragmentation of these projectiles were monitored by X-ray photographs, as well as axial residual velocity and radial velocity of behind-armor fragments. Based on these detailed experimental data, Paulus numerically investigated lateral expansion behavior and presented an analytical approach of radial expansion velocity under assumptions of weak shock and acoustic approximation. According to Paulus\' data, Verreault [, , ] conducted further numerical and theoretical investigation on lateral expansion and fragmentation of PELE jacket. Considering propagation and interaction of shock/rarefaction waves in PELE without assumptions of weak shock or acoustic approximation, Verreault managed to describe impact-induced pressure evolution in PELE filling more accurately, and developed an improved model to predict maximum radial velocity and fragmentation of PELE jacket. Verreault\'s analytical results were in relatively better agreement with Paulus\' experimental data. This indicated model built by Verreault can effectively describe lateral effect of PELE, especially for small-caliber PELE projectile against thin target at high velocity. Besides, Zijian Fan and Xiwen Ran  developed another analytical model, which also predicted maximum radial velocity more accurately than Paulus\' estimation, by assuming kinetic energy accumulated as compression energy before being perforated will be completely released as radial velocity of PELE fragments. More experiments of PELE with various jacket and filling materials with impact velocity ranging from 400 to 900 m s−1 were carried out by Zhu . Witness plates were setup very near to main target plates, in this case axial velocity differences between behind-armor fragments can be ignored, to indirectly acquire maximum radial velocity of PELE fragments according to distribution of perforated holes on witness plates. Zhu also developed an analytical model for maximum axial and radial velocities of behind-armor fragments under assumption of weak shock wave and ignorance of energy loss. Furthermore, fragmentation behavior of PELE with rotation against aluminum target at various impact angle was numerically investigated by Jiang and Zhang with stochastic model . Researches aforementioned provide effective numerical/theoretical descriptions of expansion behavior of PELE when small-caliber projectiles penetrating thin target at high impact velocity. Here we presented a similar study on large-caliber PELE projectile (130 mm) with various thickness steel jacket against 30 mm RHA plates at low impact velocity (415 m s−1). By considering an additional radial shock wave originating from transmission at jacket/filling interface, an analytical model developed by Verreault was presented to accurately describe pressure evolution, lateral expansion and jacket fragmentation in this condition. To predict damage area on behind-armor witness target that was far away (2 m) from target plate, empirical investigation were conducted, focusing on relation between maximum emission angle of PELE behind-armor fragments and maximum axial/radial velocity. Further comparisons between analytical and experimental/numerical data verified above models and then revealed influence of d/D on lateral expansion and jacket fragmentation of large-caliber PELE.