Modeling Effects of Crystalline Microstructure, Energy Storage Mechanisms, and Residual Volume Changes on Penetration Resistance of Precipitate-Hardened Aluminum Alloys

Report No. ARL-RP-266
Authors: John D. Clayton
Date/Pages: August 2009; 14 pages
Abstract: An anisotropic nonlinear crystal mechanics model is developed for a class of ductile aluminum alloys, with the intent of relating microscopic features and properties to performance of the alloys deformed at high strain rates that may arise during impact and blast events. A direct numerical simulation of dynamic tensile deformation of an aluminum polycrystal demonstrates a tendency for shear localization to occur in regions of the microstructure where the ratio of the rate of residual (i.e., stored) elastic energy to plastic dissipation is minimal. By coarse-graining predictions of the crystal plasticity framework using a Taylor averaging scheme, a macroscopic constitutive model is developed to investigate effects of microstructure on ballistic perforation resistance of plates of an Al-Cu-Mg-Ag alloy. Specific aspects of microstructure investigated include random and rolled cubic textures as well as stored elastic energy and residual volume changes associated with lattice defects, impurities, and inclusions such as second phases in the metal-matrix composite. Results suggest performance could be improved by tailoring microstructures to increase the shear yield strength and the ratio of residual elastic energy to dissipated heat.
Distribution: Approved for public release
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Last Update / Reviewed: August 1, 2009