A one-dimensional hypervelocity impact penetration model for metallic projectiles into semi-infinite metallic targets

The prediction of the crater formation and the penetration depth caused by the hypervelocity impact of projectiles into targets is a formidable effort. Most work in hypervelocity penetration mechanics is accomplished through experimentation. Extensive efforts have been made to fit data empirically, but these have not lead to an increased understanding of the mechanics of hypervelocity impact. The empirical and finite-element techniques currently used provide only an estimate of the crater formation and require an adjustment of various parameters based on experimental data. Current predictive models do not provide an accurate estimate of the penetration for all types of projectiles, because of the failure to consider all phases of the penetration process. The current work analyzes the analytical and empirical penetration methods which involve the use of the Bernoulli equation. These methods provide accurate results for long-rod projectiles (L/D > 3), but are inadequate for smaller aspect-ratio projectiles. The cavitation phase of the penetration process is usually ignored in current models, which results in inadequate estimates of penetration for low L/D projectiles. In this study, semiempirical equations, which include the cavitation phase, where developed for hypervelocity impacts involving spheres, L/D = 1 cylinders and long-rod projectiles and the results were compared to experimental data. The equations provide good correlations for a wide variety of metal-on-metal hypervelocity impacts. The only material properties required by the model are Brinell hardness of the target and the densities of the projectile and target materials.