Quantifying Bulk Plasticity and Predicting Transition Velocities for Armor Ceramics Using Hardness Indentation Tests

Report No. ARL-TR-6050
Authors: Corydon D. Hilton; James W. McCauley; Jeffrey J. Swab; Eugene R. Shanholtz; Andrew R. Portune
Date/Pages: July 2012; 32 pages
Abstract: Many studies have shown that harder ceramics generally perform better in armor applications; however, the nature of the relationship between hardness and ballistic performance is not understood to a degree that is useful in materials development. In addition, some research has suggested that a material's potential for inelastic deformation (or its "quasi-plasticity"—a bulk property) may also play an important role in its resistance to penetration. Methods of quantifying the bulk plasticity of a ceramic material are, however, extremely limited. Recently, an empirical approach has been described in which hardness tests are used to quantify bulk plasticity in structural ceramics and predict their transition velocities. The current study extends this approach to a wider variety of potential armor ceramics. For those ceramics that have been tested in dwell/penetration transition experiments, the transition velocities predicted by this approach generally show excellent agreement (within 5% in most cases) with the experimentally determined velocities. Furthermore, the robustness of the technique is demonstrated through the incorporation of multiple operators and multiple hardness-testing units.
Distribution: Approved for public release
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Last Update / Reviewed: July 1, 2012