Solution to problems caused by associated non-quadratic yield functions with respect to the ductile fracture

Accurate material behaviour and its response to loading are needed for a reliable calibration of ductile failure criteria. Non-quadratic yield functions often necessary such description. Nevertheless, it leads the prediction stress states that inconsistent with expected deformations in contradiction experiments when associated flow rule is adopted. These problems may be solved by applying less restrictive non-associated rule. Therefore, an isotropic non-quadratic phenomenological plasticity model was developed as function second third invariants deviatoric tensor. The convex proposed allow different stresses tension, compression shear. For simplicity, same used plastic potential. Each these described seven parameters. scheme so-called next increment corrects error method adopted implementation within finite elements. Above that, three additional models were calibrated 2024-T351 aluminium alloy. It shown how resolves above-mentioned problems. Moreover, possible extensions include hydrostatic dependence.