On the efficiency and accuracy of stress integration algorithms for constitutive models based on non-associated flow rule

Constitutive models based on non-associated flow rule enable the accurate description of complex anisotropy phenomena by using distinct, but relatively simple, mathematical description for yield function and plastic potential. The computational complexity of stress integration procedure may thus be significantly reduced. The amount by which this advantage is reflected to the total computation time is, however, a function of the nonlinearity of the problem at hand. The present work aims to make a systematic comparison of two different stress integration algorithms, used in conjunction to non-associated flow rule. A fully explicit and semi-implicit integration scheme are analyzed in terms of accuracy and speed. The implemented yield model is Yld2000-2d with isotropic hardening. The validity of the stress-integration approaches is assessed based on the ability to reproduce stress-ratios, r-values and tensile test results. Additionally, measured earing profiles in cup drawing experiments are compared. The fully explicit implementation shows significant advantages in terms of speed.