42nd International Deep Drawing Research Group Conference - IDDRG 2023

The need for efficient mechanical component design has led the scientific community to evaluate the mechanical properties of anisotropic materials under multiaxial loadings. The mechanical behaviour of the aerospace grade AA2219 sheet was evaluated under planar biaxial stress conditions. The in-house designed cruciform specimen provides uniform strain and fracture in the gauge region. The load control tests were performed under different stress ratios of 0:1, 1:2, 3:4, 1:1, 4:3, 2:1, and 1:0 to develop yield locus. Online strains were measured using a digital image correlation (DIC) technique. Up to 40% strain of the sample tested at uniaxial loading conditions was achieved under equal-biaxial conditions, and the fracture was observed at the gauge area. The yield strength of the material increases, and the ductility decreases due to the stress triaxiality generated by biaxial loading. Effective young's modulus and effective strain hardening coefficient are calculated to understand the work-hardening behaviour of the material. To draw a yield locus till fracture plastic work-equivalence method was used to calculate stress coordinates for each biaxial test in stress space. The yield locus obtained by experimental data is compared with various phenomenological models such as Von Mises, Hill's 48, Hill's 93, and Barlat's 89. Barlat 89 predicts material behaviour more accurately than other models with exponent 12. Microstructural characterization, including fractography, EBSD, and Bulk texture, was performed to correlate material behaviour more distinctly under biaxial loading conditions.

Keywords – Planar Biaxial Test, Yield Locus Development, Texture Evolution