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Albuquerque, NM, United States

Warren T.L.,3804 Shenandoah PL. NE
International Journal of Impact Engineering

In this article, we investigate in further detail the differences between quasi-static and dynamic penetration models based on the spherical cavity-expansion approximation for rigid ogive-nose long rod steel projectiles that penetrate aluminum targets at normal impact over a range of striking velocities. Comparisons of experimental data with predictions from a preveously published incompressible power-law strain hardening penetration model that includes target inertia effects derived from a spherical cavity-expansion solution show excellent agreement for striking velocities to 1800 m/s. However, predictions from a previously published incompressible penetration model derived from a quasi-static spherical cavity-expansion solution that neglects target inertia effects loses accuracy with increasing striking velocity. In this work, we illustrate the effects that target inertia has on the deep penetration of rigid ogive-nosed long rod steeel projectiles that strike aluminum targets with normal impact over a range of striking velocities. This comparison is achieved by employing the cavity-expansion approximation with solutions for quasi-static and dynamic incompressible power-law strain hardeniong spherical cavity expansion solutions. These results indicate that the magnitude of the target inertia effects depends on striking velocity, projectile geometry and nose shape, projectile density, and target material properties. © 2015 Elsevier Ltd. All rights reserved. Source

Warren T.L.,3804 Shenandoah PL. NE | Forquin P.,Grenoble Institute of Technology
International Journal of Impact Engineering

In this paper, we employ a dynamic spherical cavity-expansion solution for use with the spherical cavity-expansion approximation to analyze the penetration of common ordinary strength water saturated concrete targets by small scale rigid ogive-nosed projectiles with normal impact. To do this, we first obtain a quasi-static spherical cavity-expansion model for the radial stress at the cavity surface of a plastic-cracked-elastic material. Next, we add on a target inertia based term to the quasi-static radial stress at the cavity surface to obtain an approximate expression for the dynamic radial stress acting at the surface of the spherical cavity. This spherical cavity-expansion solution is employed with spherical cavity-expansion approximation based penetration models that previously required prior depth of penetration data to obtain the quasi-static target resistance function. With the newly proposed penetration models, a description of the common ordinary strength water saturated concrete material is based on a linear pressure-volumetric strain relation and a pressure dependent shear strength plasticity envelope with a tensile cutoff and is obtained from laboratory scale material tests; therefore, no prior depth of penetration data are required. Analytical model predictions obtained with the newly proposed model for final depth of penetration as a function of striking velocity, along with analytical models for acceleration, velocity and displacement as a function of time, are shown to be in good agreement with the corresponding experimental penetration data. © 2015 Elsevier Ltd. Source

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