A fair description of the plastic anisotropy of thin sheet metals plays an important role in forming operations, once material flow, springback as well as wrinkling and limit strains are significantly affected by the yield criterion used in the analysis. Such a criterion is a relationship which identifies the stress states capable to produce the transition of the material from the elastic domain to the plastic one. This relationship can be interpreted as being the equation of a geometrical entity in the stress space (the so-called yield surface). In the analytical relationships that describe the yield criteria, the components of stress tensor are accompanied by material parameters. The values of the parameters are determined using experimental data. During the last years, new yield functions were introduced in order to improve the fitting of the experimental results, especially for aluminium and magnesium alloys [1]. The CERTETA team has developed several anisotropic yield criteria [2],[3]. The paper presents a test used to estimate the predictive accuracy of a few yield criteria for anisotropic materials. The study is focused on the yield criteria developed at the CERTETA research center. The performances of the models have been tested on two sorts of sheet metals widely used in the industry: steel SPCEN and an aluminium alloy AA3103-0. The results (predicted yield locus, distributions of the uniaxial yield stress, anisotropy coefficients) show the influence of the number of material parameters included in the identification procedure on the accuracy of the criteria.
Artykuł przedstawia test wykonany w celu oszacowania przewidywanej dokładności kilku kryteriów plastyczności dla materiałów anizotropowych. Działanie modeli zostało przetestowane na przykładzie blachy cienkiej ze stopu aluminium AA3103-0 szeroko stosowanej w przemyśle. Wyniki (oszacowanie miejsca płynięcia materiału, jednoosiowy rozkład granicy plastyczności, współczynniki anizotropii) pokazały wpływ wielu parametrów materiału uwzględnionych w procedurze identyfikacji na dokładność analizowanych kryteriów