Ballistic impact of anisotropic 2024 aluminum sheet and plate

2024 Aluminum sheet and plate are known to have anisotropic strength characteristics with regard to plasticity. However, numerical investigations of the impact behavior of sheet metals rarely consider anisotropic behavior. The effect of anisotropy in an impacted 2024 aluminum target is investigated experimentally and numerically. Normal impact experiments of titanium alloy and tool steel projectiles, with impact velocities ranging from 190 to 299 m/s, into 3.175 mm thick 2024-T3 sheet and 12.7 mm thick 2024-T351 plate are presented. Rear surface strains and displacements are measured using three-dimensional digital image correlation (DIC). Simulations of selected impact experiments, using a six-component anisotropic plasticity model for the target, are compared to the experimental data. Two model parameter sets are used. The first set accounts for initial anisotropic strength properties of the target, while the second reduces to an isotropic (von Mises) yield function. The objective of the numerical simulations is to study the difference in the results between the anisotropic and isotropic parameter sets. Results show that the yield function parameters used for simulations of both the 3.175 mm sheet and 12.7 mm plate have a significant effect on the calculated residual velocity of the projectile. The anisotropic parameter set simulations agree with experimental rear surface panel displacements and strains for both target thicknesses. There is experimental evidence of anisotropic deformation behavior only in the case of the 3.175 mm thick 2024-T3 target panels. The results demonstrate that the form of the yield function has a significant effect on the results of the impact simulations. (C) 2013 Elsevier Ltd. All rights reserved.