The fundamental assumptions of cavity expansion models for penetration - revisited

Abstract

The fundamental assumptions motivating the use of cylindrical (CCE) and spherical (SCE) cavity expansion solutions for the prediction of penetration mechanics are revisited. Predictions of an ovoid of Rankine model (OR), which has been validated relative to axisymmetric numerical simulations, are used as a reference solution for normal penetration into a metallic target. In previous papers it has been observed that the average axial resistance stress is independent of the penetration velocity until a critical value which denotes the onset of separation of the target material from the projectile’s surface. The main conclusion of this paper is that the velocity fields in the CCE and SCE models do not accurately model a realistic flow field for penetration of a projectile. The results in this paper quantify the errors caused by low estimates of the static resistance stress and compensation due to incorrect dependence of the resistance stress on the penetration velocity predicted by the CCE and SCE models.