Fracture envelopes on the 3D-DIC and hybrid inverse methods considering loading history

Abstract

This paper deals with the comparative investigation of fracture envelopes constructed by the 3D-DIC and hybrid inverse analyses. For the evaluation of fracture limits of the DP980 12t steel over a wide range of loading conditions, tensile tests were conducted using three different specimens that are expected to induce certain stress states of plane strain tension, in-plane shear, and uniaxial tension at the potential location for the fracture initiation. The modified Mohr-Coulomb ductile fracture criterion was selected in this study to investigate the influence of the fracture envelope identification based on each way of loading history evaluation not only on the level of fracture limits but also on the fracture prediction especially for the simulation of square cup deep drawing. For an in-depth understanding of non-linear loading history on the variation of ductility limit, apparent fracture with respect to strain was numerically computed according to the change of loading path. Finally, a comparison of results from the square cup deep drawing test and the FEA prediction was performed in terms of punch force and stroke to confirm the model performance at various ways of the loading history evaluation.