The present study suggests a complete analytical model for armour perforation by ductile hole enlargement process. The new approximate model is applicable for entry, tunnelling and exit phases of a rigid nose-pointed projectile with an arbitrary nose-shape. The theory is based on dividing the target into infinitesimal thin layers, in which a cylindrical hole expansion is assumed. The elastoplastic work that is consumed by the target for infinitesimal projectile advancement is based on the specific cavitation energy and leads to reduction of the projectile kinetic energy. Several equivalent formulae for ballistic limit velocity, and a formula for the ballistic limit thickness are found to be independent of projectile nose-shape and nose length. The approximate model is compared with numerical simulations for AA6061-T651 targets that are impacted by two different ogive nose-shape projectiles at several striking velocities. A small nose-shape effect on the ballistic limit velocity is observed in the numerical simulations and is attributed mainly to the target axial effect and the bulge formation at the target rear surface, which are not considered in the approximate model.

中文翻译：

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延性扩孔装甲穿孔的近似理论

本研究提出了一个通过延性扩孔过程进行装甲穿孔的完整分析模型。新的近似模型适用于任意弹头形状的刚性弹头弹头的进入、掘进和退出阶段。该理论基于将目标划分为无限小的薄层，其中假设圆柱孔扩张。目标在无穷小的射弹前进时消耗的弹塑性功基于特定的空化能，并导致射弹动能减少。发现弹道极限速度的几个等效公式以及弹道极限厚度的公式与弹头形状和弹头长度无关。将近似模型与 AA6061-T651 目标的数值模拟进行比较，这些目标受到两种不同的尖头形状射弹以几种打击速度的撞击。数值模拟中观察到弹道极限速度存在较小的鼻形效应，这主要归因于目标轴向效应和目标后表面的凸起形成，而近似模型中没有考虑这些效应。