Analytical engineering models of high speed normal impact by hard projectiles on metal shields

In this review we consider mainly relatively simple engineering models which can be physically substantiated although usually their justification requires a large number of assumptions. These models are characterized by the following features in the case of normal impact: either they determine the relations between the ”integral characteristics” of penetration (depth of penetration, ballistic limit velocity) in the explicit form (in algebraic form or including quadratures) or they describe local interactions between the shield and the penetrator in the points of the penetrator-shield contact surface that yield such integral characteristics. In this overview we present more or less comprehensively all widely used and also not well known analytical models which have been suggested for describing high-speed penetration into metal shields. This survey is characterized by the following distinguishing features: (i) includes an unprecedented large number of models; (ii) presents models suggested during recent years; (iii) analyzes models which have been originally published in Russian and are not well known in the West.