Analysis of jacketed rod penetration

An analytical model for the cratering process in a metal target due to high-velocity penetration of a jacketed rod has been developed. The jacketed rod consists of a central high-density core surrounded by a low-density jacket. The analysis is based on the observation that two mechanisms are involved in the cavity growth by eroding rods: flow of rod erosion products, which exerts radial stress on the target and opens a cavity, and radial momentum of the target as it flows around the rod front nose. Hence, the mushrooming effects on the cavity growth are isolated. The model includes the centrifugal force exerted by the core and jacket, radial momentum of the target, and the strength of the target. A criterion for the onset of “bi-erosion”, where there exist two stagnation points such that the performance is different significantly from the homogeneous rods, is obtained from the model. Predicted results for the final cavity diameter are found to match well with the corresponding test values. Further numerical simulations are conducted and indicate that as long as “co-erosion” occurs the penetration performance of jacketed rods is governed by the aspect ratio not of the jacketed rod but of the high-density core rod.