Influence of advanced yield criteria on predictions of plastic anisotropy for aluminium alloy sheets

Extruded aluminium alloy sheets of AA7003-T6 are characterised by performing an experimental programme and numerical simulations. The anisotropic behaviour of the aluminium alloy is investigated using two linear transformation based anisotropic yield criteria Yld2000-2d (Barlat et al. [1]) and Yld2004-18p (Barlat et al. [2]). The yield criteria are calibrated using previously reported measured values of flow stress ratios and strain ratios obtained from uniaxial tensile tests and disc compression tests. The results from the model calibrations show that Yld2004-18p gives improved prediction. The evaluation of the selected yield functions is extended by performing numerical simulations of in-plane shear tests and plane-strain tension tests using the general-purpose non-linear FE code LS-DYNA. The results from the simulations show that the constitutive model based on Yld2000-2d predicts too low strength for the determined model parameters and indicates that the shape of the yield surface is inadequate. Predictions with the constitutive model based on Yld2004-18p gave better agreement with the experiments.