An engineering penetration/perforation model of hemispherical nosed rigid cylindrical rods into strain-hardening targets

Abstract

We propose a four-stage model of the penetration/perforation by hemispherical-nosed rigid cylindrical rods into targets whose materials exhibit strain-hardening effects. During each stage of the penetration process, a kinematically admissible velocity field involving one or more unknown parameters is assumed. These parameters are determined by minimizing the rate of plastic dissipation. From this velocity field, the incremental deformations of the target, the penetration depth, the resisting force acting on the penetrator and hence its deceleration are evaluated. We propose a criterion for the formation and ejection of the cylindrical plug in the target and use it to study problems involving the perforation of the target. Computed results for the exit speed of the penetrator and, when the targets are not perforated, of the penetration depth are found to match well with the corresponding test values.