Numerical derivation of strain-based criteria for ductile failure: Discussions on sensitivity and validity

The structural application of HSLA steels can be fostered by considering their ductile failure properties in design. To achieve this we discuss an approach to numerically derive Johnson-Cooks criterion from GTN simulations. The critical state is assumed to be the onset of softening within a global neck. Due to the non-uniqueness of the GTN parameters a calibration scheme is required to enhance the reliability of the procedure. Such a scheme is proposed and tested on the basis of a GTN sensitivity study. With the proposed procedure the strain-based design criterion can reliably be derived for triaxialities higher than 1.0.