Constitutive Response of AA7075-T6 Aluminum Alloy Sheet in Tensile and Shear Loading

Abstract

Tensile and shear experiments were performed on AA7075-T6 sheet at strain rates ranging from quasi-static (0.001 s⁻¹) to high (1000 s⁻¹) in three sheet orientations (0°, 45° and 90°) with respect to the rolling direction. Digital image correlation (DIC) techniques were employed to measure the strains in the experiments. The AA7075-T6 alloy showed mild rate sensitivity over the range of strain rates tested. The level of plastic anisotropy was characterized and was shown to be rate-insensitive. The quasi-static experimental data was used to calibrate the eight-parameter Barlat YLD2000 anisotropic yield criterion to describe the anisotropic behaviour of the sheet material. The quasi-static hardening behaviour to large strains was also experimentally determined by converting the shear stress to an equivalent uniaxial stress and fit using a Hockett–Sherby model. The calibrated anisotropic yield criterion was able to capture the material anisotropy providing good agreement with the experiment data.