Effects of strain hardening and strain-rate sensitivity on the penetration of aluminum targets with spherical-nosed rods

We present penetration equations for rigid, spherical-nosed rods that penetrate 6061-T651 aluminum targets. The penetration models use the spherical cavity-expansion approximation and constitutive equations for the target that include strain hardening and strain-rate sensitivity. We obtained closed-form penetration equations for an incompressible target material; however, predictions for a compressible target require the numerical solution of a coupled set of nonlinear ordinary differential equations. Numerical results show the effects of compressibility, strain hardening, and strain-rate sensitivity. We also show that our penetration model requires compressibility, strain hardening, and strain-rate sensitivity to obtain good agreement with previously published depth of penetration data for striking velocities between 300 and 1200 m/s.