Prediction of ductile fracture for advanced high strength steel with a new criterion: Experiments and simulation

Abstract

This paper is concerned with prediction of the onset of ductile fracture by a newly proposed micro-mechanism-motivated macroscopic ductile fracture criterion in various stress states from shear to plane strain tension where most ductile fracture takes place in sheet metal forming processes. The new ductile fracture criterion (Lou et al., 2012) is calibrated by the equivalent plastic strain to fracture measured by the hybrid experimental-numerical method from four types of specimens manufactured from DP980 sheet whose fracture locus is eventually constructed. The calibrated criterion is utilized to construct the fracture locus of DP980. The constructed fracture locus is then implemented into the ABAQUS/Explicit code to predict the onset of ductile fracture for these three types of specimens. Three types of notched specimens are further designed for the validation of the ductile fracture criterion from uniaxial tension to plane strain tension by comparison of experimental results to those numerically predicted by the ductile fracture criterion. Three types of shear specimens are then utilized to validate predictability of the ductile fracture criterion between shear and uniaxial tension. The validation demonstrates that the ductile fracture criterion can accurately predict the onset of ductile fracture for these specimens. The comparison result with high accuracy reveals that the criterion can correctly describe ductile fracture behaviors of metals in various stress states from shear to the plane strain tension.