Improvement of modified maximum force criterion for forming limit diagram prediction of sheet metal

This study presents a new criterion (MMFC2) for predicting the forming limit curve (FLC) of sheet metal. The strain path evolution critical element examined in uniaxial tensile test is elaborated by incorporating results experimental measurement, finite simulation, and theoretical prediction via Modified Maximum Force Criterion (MMFC). A scaling factor introduced to mimic evaluation with simulated one. It believed that rotation principal axes theoretically considering material point, which initially co-axial external load coordinate, implicates macro track change. Furthermore, an optimal event second derivative axial rotations proposed indicate localization formulate FLC. performance compared original MMFC FLC three automotive metals, all related data were published Benchmark Numisheet 2014 conference. use different hardening laws yield functions analogy. comparison reveals MMFC2 are more sensitive employed constitutive model than MMFC. concordant data. Nakajima tests conducted CR4 mild steel sheets validate capacity criterion. Well agreement between experimentally measured based on Yld2k function verifies its usefulness practice.