Uncoupled ductile fracture criterion considering secondary void band behaviors for failure prediction in sheet metal forming.

• A new phenomenological ductile fracture criterion considering micro mechanisms of void nucleation, void growth, and evolution of void coalescence is presented in this paper. • The secondary voids band and rotation of voids effect are considered in the new ductile fracture criterion. • The new ductile fracture criterion can be utilized for predicting initial fracture in sheet metal forming with lager range of stress triaxiality. A new phenomenological ductile fracture criterion that is proposed. The proposed model is associated with the micro mechanisms of void nucleation, void growth, and evolution of void coalescence. The secondary voids band and rotation of voids effect are considered in the new ductile fracture criterion. A series of upsetting test results of aluminum 2024-T351 and TRIP RA-K40/70 steel are used to construct and compare the accuracy of fracture locus proposed by new ductile fracture criterion, Modified Mohr-Coulomb criterion and extend Lou-Huh criterion. The fracture locus constructed using the proposed criterion is close to the experimental data points over a wide stress state range from uniaxial compression to balanced biaxial tension. Then, a series of upsetting tests and square cup drawing tests are conducted with Al6014-T4 to evaluate the accuracy of the proposed criterion. All results indicate that the proposed ductile fracture criterion can be utilized for predicting initial fracture in sheet metal forming. Image, graphical abstract [ABSTRACT FROM AUTHOR]