Wrinkling prediction for GPa-grade steels in sheet metal forming process

This paper newly proposes a phenomenological wrinkling criterion to predict the formation of severe wrinkling in GPa-grade steels by adopting a critical amount of compressive strain with respect to the specific triaxiality and the geometrical bending strain, which were updated incrementally. To enhance the accuracy of the wrinkling criterion during the sheet metal forming process, the non-flange and flange wrinkling criteria were separately applied to the adapted region, which was distinguished from the entire domain by checking the blank holding pressure (BHP) caused by the contact pressure between the sheet and binder, systematically. The proposed wrinkling criterion exhibits superior performance in the prediction of experimental wrinkles that occur in the B-pillar and crash forming with a TRIP1180 sheet when compared with conventional criteria such as geometrical bending strain, thickness strain, and potential wrinkling.