Review of hypervelocity penetration theories

A review is given of the empirical and approximate theoretical expressions which have been developed to describe various aspects of impact at hypervelocities where the projectile and some of the target materials undergo massive plastic deformation, breakup, melting or vaporization. Various stages of the penetration process are identified on the basis of experimental evidence. Empirical fits to experimental data, or, at velocities above the experimental range, to results of finite difference calculations of the penetration event, are reviewed. In some cases simple theories, usually requiring the evaluation of some undetermined parameters from experimental or numerical data, have been developed. These are described, with emphasis on those which have found use in the design of offensive or defensive systems