The Role of the Yield Criterion on Stress and Strain Paths Under Non-proportional Loadings

Recent studies highlight the importance of improving the description of the material behavior, particularly for non-proportional loading paths. This work discusses the differences in the stress and strain ratios predicted by different yield criteria, when applied to describe the plastic behavior of an aluminum alloy, submitted to different non-proportional biaxial loading conditions. Reloading with or without unloading is analyzed to highlight the importance of the unloading stage on the stress paths, since the stress state cannot change abruptly for a material undergoing plastic deformation. Although the yield criteria adopted seem to have a small impact on the stress state predicted for each force-controlled loading condition, the influence on the strain path is non-negligible.