Mass loss and blunting during high-speed penetration

A new analytical model of high-speed friction was developed to account for the observed velocity dependence in sliding friction at high speeds and was successfully applied to the analysis of data previously reported by Jones et al. for a number of concrete penetration tests using ogive-nose projectiles of high-strength steel alloy. The model permitted very consistent predictions of penetrator performance and target strength based on the experimental data. The subsequent development by Davis et al. of a stepwise incremental approximation to the velocity-dependent coefficient of sliding friction simplified the implementation of the model, while preserving the quality of the linear approximation to the assumed velocity dependence in sliding friction at high speeds. The stepwise function further led to an engineering model for mass loss, neglecting the effects of blunting, which successfully related the work done by friction to the mass loss due to surface melting of the nose. In this paper, a generalized dimension less nose equation is developed, allowing these results to be applied to geometries other than the ogival case. Furthermore, the effects of blunting and progressive mass loss from the nose are incorporated into the existing model of high-speed penetration and applied to the analysis of previously reported penetration data. By incorporating changing nose mass and geometry due to frictional wear, the performance characteristics of steel alloys and selected nose geometries can be better evaluated, and the processes governing high-speed penetration and mass loss better understood. Given penetrator material, impact velocity and target properties, it is also possible to predict the performance of various nose geometries.