In this paper the Burzynski criterion, which was introduced for isotropic pressure-dependent materials, is modified for anisotropic pressure-dependent materials in plane-stress condition. The modified criterion can be calibrated with 10 experimental data points such as tensile stress at 0, 45 and 90, compressive stress at 0 and 90 and R-values in tensile stress at 0, 45 and 90 from rolling direction and also biaxial tensile stress and tensile R-value. To identify the anisotropic parameters an error function is set up through comparison of the predicted yield stresses and R-values with those from experiments. Then the Downhill simplex method is applied to solve 10 high-nonlinearity equations. Finally, considering Al 2008-T4 (BCC), Al 2090-T3 (FCC), AZ31 (HCP) and also Mg–0.5% Th alloy, Mg–4% Li alloy, pure textured magnesium, textured magnesium and Ti–4Al–1/4O2, which are HCP materials with ep ¼ 1%; 5%; 10% as case studies and comparing the results for the modified Burzynski criterion with experiments, it is shown that the Burzynski criterion is appropriate for pressure-dependent anisotropic materials with proper accuracy.

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