DEFORMATION AND PERFORATION OF SPHERICAL-SHELLS BY NORMAL IMPACT OF BLUNT-ENDED PROJECTILES

An approximate quasi-static theory is developed to predict large plast ic deformation and perforation of spherical shells subjected to impact by blunt-ended projectiles at normal incidence. Based on experimental observations for quasistatic load-displacement characteristics, the p roblem of a spherical shell under normal impact by a flat-ended missil e may be analyzed through the solutions to that of an equivalent circu lar plate struck transversely by the same missile. It is shown that th e approximate theoretical predictions with alpha = 30 (here alpha is a n empirical constant) are in good agreement with experimental data, in terms of maximum permanent transverse displacements and dimple radii. Furthermore, a theoretical formula for ballistic limits of spherical shells under missile impact is presented and the range of applicabilit y of the theory is discussed.