Numerical prediction of ductile fracture in multi-stage single point incremental forming based on phenomenological modified Mohr-Coulomb

Since the conventional simulation for multi-stage single point incremental forming cannot describe the phenomenon of ductile fracture of material, the suitability of a deformation strategy is not evaluated. Therefore, the numerical prediction of ductile fracture is especially significant for the application and development of MSSPIF. In this paper, the calculation of forming stages and the evaluation criteria of ductile fracture are separately established to design intermediate profiles and to estimate initial crack of material for MSSPIF of straight wall parts based on phenomenological modified Mohr-Coulomb. Moreover, the effect of some factors (stress triaxiality, normalized Lode angle, and forming stage) on ductile fracture is analyzed in detail, and then a high-precision finite element model coupled MMC3 is established to predict the ductile fracture of material during MSSPIF. Meanwhile, the fracture forming limit diagram for MSSPIF is also obtained and higher than that obtained by single-stage single point incremental forming. (C) 2020 Elsevier Ltd. All rights reserved.