Strain hardening exponent role in phenomenological ductile fracture criteria

• Modification of three uncoupled ductile fracture criteria is proposed.
• Modified versions lead to better approximation of fracture envelope.
• Alternative design of universal biaxial calibration specimen is presented.
• Strain based error analysis is discussed.

The performance of ductile fracture criteria often depends on the accuracy of material constants identification. Calibration process of three uncoupled phenomenological models was analysed. All of them contain the strain hardening exponent which is related to material plasticity as one of the fracture criteria parameter. More flexibility, better approximation of the fracture locus and more convenient shape of the fracture envelope might be reached when the strain hardening exponent is considered as another independent parameter of the fracture criteria in the identification process. Results are illustrated on the example of two structural steels, AISI 316L and AISI 1045, respectively.