Modifications to Walker-Anderson Model for Analysis of High-velocity Penetration of an Eroding Long-rod Projectile into Semi-infinite Concrete Targets

This paper presents a modified form of the Walker-Anderson (W-A) model for analyzing high velocity penetration of an eroding projectile into a concrete target in which the W-A model is improved by incorporating calculations for the plastic flow field of concrete in terms of its compressibility and strain rate sensitivity under severe pressure. With the changes to and calculations of plastic field in concrete targets, equations of penetration were rearranged. Solution of equations gives penetration depth, penetration velocity, projectile rod velocity and length of a projectile instantaneously. Results of this analysis were compared with experiments performed by authors of this paper`. Experiments were performed in order to test eroding long-rod (9≤L/d≤11) penetration into semi-infinite concrete targets at high impact velocities (650 (m/s) v 1150 (m/s)). Comparisons show overall agreement between results of the analysis and experiments (average error was 12%). In cases where it is not possible to perform the experiments, the results of the modified model have been compared with the numerical simulations performed by the authors in the literature. Parametric study performed in this paper showed that the two parameters- “plastic flow field characteristic α” around the projectile tip in the target and unconfined compressive strength of the concrete- are two key parameters influencing the results. The study showed that the level of importance of plastic flow field characteristic is high in forming the resistance against eroding penetration and its effect is not less than the unconfined compressive strength of concrete.