The Importance of the Cavitation Effective Yield Stress and the Hole Slenderness Ratio for Accurate Predictions of Ballistic Limit Velocities

Abstract

Perforation and penetration mechanics research is mostly governed by experimental and numerical investigations while analytical models are less available due to the extremely complicated nature of the subject. Sufficiently thick ductile targets are perforated by rigid, nose-pointed projectiles in a ballistic process whose dominant failure mode is ductile hole enlargement. Several recent studies have shown that for perforation process by ductile hole formation, the specific cavitation energy, which reflects the target material resistance to steady hole expansion, is essential for analytical predictions of ballistic limit velocities. The ballistic limit velocity is the minimum impact speed that is required for complete perforation of a given target by a given projectile. A logarithmic formulation for the specific cavitation energy of metal targets, which is based on the concepts of (spherical cavitation) effective yield stress and hole slenderness ratio, is shown in several recent studies to be very useful for analytical predictions of ballistic limit velocities. The logarithmic formulation for the specific cavitation energy is presented, and the concepts of cavitation effective yield stress and hole slenderness ratio are reviewed and discussed regarding their importance for accurate analytical predictions of ballistic limit velocities. The present article is a review of these two concepts and their usefulness in perforation mechanics.