In this paper, the modified form of Jones et al, model introduced by Moustafa et al. [1], Model I, describing the penetration of a thick metallic target by a continuous rod is examined for the following conditions: (i) the rod impact velocity is greater than 1.5 km/s and (ii) the rod aspect ratio is greater than 10. The predicted depths of penetration are compared with experimental measurements of Buchar et al. [2]. Model I proves its limited predictive capabilities; it can be only applied to describe the penetration of a long rod into a thick metallic target at impact velocities less than 1.6 km/s.
Moreover, the hydrodynamic theory developed by Tate [3,4] is modified herein by considering the essential dependence of target strength factor on the rate of its material deformation. Three different forms are used to determine the target strength factor; one is linear, whereas the other two forms are non-linear. The linear form correlates the target strength factor with rod impact velocity. The first non-linear form correlates this factor with rod impact velocity, whereas the second correlates it with rod impact velocity and aspect ratio. The modified Tate model, Model II, is used to cover the deficiencies of Model I. The predicted depths of penetration of Model II are compared with experimental measurements of Buchar et al. [2]; good agreement is generally obtained when the linear form that determines the target strength factor is used. Model II is also used to predict samples of time histories of penetration depth and rod residual length due to the impact of high-speed long steel rods of different strengths into thick steel targets. In addition, the model is used to study the influence of rod strength and impact velocity, respectively, on the depth of penetration and the rod residual length.