A note on the deep penetration and perforation of hard projectiles into thick targets

Two models were proposed in this note. Firstly, by assuming that the resistance acting on the projectile keeps unchanged during the penetration process, the new mean resistance approach based on dynamic cavity-expansion approximation was proposed. A simple unified model was further given to predict the depth of penetration (DOP) of different nose-shaped hard projectiles penetrating into diversified targets (e.g. concrete, metal, rock). Besides, the related mean resistance coefficient was confirmed as 0.4 based on the parametric analyses. Secondly, an experiment-based simplified semi-analytical perforation model for the thick concrete slab was obtained, in which the rear crater height was suggested as 2.5 times of the projectile diameter, and the ejecting velocity of rear shear fragment was advised as 20% of the residual velocity of projectile after perforation. The existing method for predicting the rear crater height was improved and the kinetic energy carried by the rear scabbing fragments were considered quantitatively. Finally, by comparing with the available test data, the prediction accuracy for DOP and residual velocity as well as the concise expressions of our models were validated. •The new mean resistance approach during hard projectile impact was introduced.•A simple unified penetration model for diversified targets was proposed.•A simple projectile perforation model for thick concrete panel was further given.•Model predictions show high degree of accuracies by comparing with the available test data.