Hardening of a rolled sheet submitted to radial and complex biaxial tensile loadings

Biaxial tensile tests are performed on cruciform specimens with the help of direct biaxial testing machine. Small offset-strain yield curves are detected on an aluminium alloy (AL1200) rolled sheet submitted to irreversible radial and complex biaxial tensile loadings. A predominant kinematic hardening and an important isotropic expansion are observed. A yield curve distortion is observed as well but, unlike the traction–torsion case, its intensity appears to be linked to the loading type. Moreover, the strain responses are analyzed in order to point out the pronounced anisotropy of the rolled sheet and to check if the sheet behavior is in agreement with a plastic flow associated with the yield curve.