Scaling of wear in kinetic energy penetrators

A new approach to the wear kinetics in kinetic energy (KE) steel penetrators is presented in this paper. The range of terminal velocities is analyzed up to ∼1300m/s. Ballistic experiments indicate that below hydrodynamic transition a significant erosion of steel penetrators is observed with concrete targets. As a rule, the shape of the nose region is significantly changed as a result of the penetration process, and smaller erosion is found in the shank region. Since during material removal the nose region is considered as a critical one, detailed studies of the wear rate were undertaken, and the results are presented in this paper. The analysis of wear rate is based on the data collected by personnel at Sandia National Laboratories, as well as by personnel at the Air Force Research Laboratory Munitions Directorate Damage Mechanisms Branch (AFRL/MNMW), located at Eglin Air Force Base, Florida for concrete targets and 4340 steel penetrators. It was found that a proper normalization of penetration experiments performed with different scales leads to the universal parameters defined as the rate of wear and the rate sensitivity of wear. These universal measurable quantities establish an effective measure of the wear intensity during penetration. Many physical processes may contribute during high-speed erosion, including melting, phase transformation and others; in this paper more details of the wear mechanism by ejection of the melt material are discussed. The model described herein permits for estimation of the order of the rate of wear and the velocity sensitivity of wear.