Penetration of laminated Kevlar by projectiles-II. Analytical model

analytical representation of the normal impact and perforation of conically-tipped hard-steel cylinders with an aspect ratio of three on laminated Kevlar 29/polyesler targets was developed to accompany corresponding text information. The global deflection was obtained using laminated plate theory; dissipative mechanisms including indentation of the striker tip. bulging at the surface, fiber failure. delamination and friction were modeled using certain simplifying assump tions. The event was divided into three consecutive phases: indentation, perforation and exit. Resistive forces for each of these mechanisms. valid for both static and dynamic penetration. were ascertained and. for the latter case. used in conjunction with Newton's law to provide the plate respons and the kinematic history of the projectile. A finite difference scheme was employed lo obtain the numerical results.A comparison of the ballistic limits and of terminal velocities for higher initial speeds obtained from the model and from tests showed very good agreement. The accord between predicted and measured displacement histories is satisfactory. but deteriorates successively when velocities and accelerations are examined. This effect is due to the process of difTerenliation of data as well as inaccuracies in the analytical rcprcsentation. Methods for extending the model arc suggested.