Research on the forming and penetration characteristics of collinear EFP warhead with double-layer liners

The widespread deployment of Explosive Reactive Armor (ERA) has qualitatively enhanced the battlefield survivability of modern main battle tanks and heavy infantry fighting vehicles. The conventional Explosively Formed Projectile (EFP) warhead, which generate a single projectile, is insufficient to effectively destroy armor targets equipped with ERA. This limitation has created a significant performance gap in existing anti-armor systems. In response to the threat posed by ERA, the Collinear Explosively Formed Projectiles (CEFP) warhead has been developed as a novel, high-efficiency warhead designed to meet this operational requirement. The CEFP warhead employs a multi-layered liner structure. Upon detonation, it forms multiple EFPs that separate sequentially along the axis, each retaining penetrative capability. The leading EFP is intended to perforate the front plate or initiate the ERA, while the trailing EFP consecutively penetrates the primary armor. This mechanism significantly enhances the destructive potential against composite "ERA + Primary Armor" configurations. However, a critical challenge for this type of warhead lies in the suboptimal kinetic energy matching between the leading and trailing damage elements. To address this challenge and effectively defeat the composite protection system of ERA and primary armor, a coaxial double-layer liner EFP warhead featuring an "externally thin, internally thick" asymmetric liner structure is proposed. A comprehensive investigation into its formation mechanism and penetration characteristics was conducted through theoretical analysis, numerical simulation, and experimental validation. This study elucidated the influence of the liner thickness ratio on the kinetic energy of the leading and trailing EFPs. Research findings indicate that a single detonation of this warhead generates two axially separated EFPs with a significant velocity differential, both possessing penetration capability. It thereby achieves a sequential attack function: the leading EFP triggers the ERA, and the trailing EFP penetrates the primary armor. Under the constraint of a constant total liner mass, the velocity differential between the leading EFP and the trailing EFP can be continuously adjusted within a range of 78 m/s to 357 m/s by varying the thickness ratio of the outer and inner liners. Concurrently, the kinetic energy distribution ratio between the two projectiles can be flexibly configured within the range of 1:5.5 to 4.2:1. The feasibility of this innovative design has been successfully verified through static detonation testing of the warhead prototype.