Modeling the strain localization of shell elements subjected to combined stretch-bend loads: Application on automotive sheet metal stamping simulations

This study presents a modeling approach for predicting strain localization during sheet metal stamping processes focused on automotive engineering applications. The so-called stretching-to-bending ratio, rho, is proposed to characterize the loading conditions acting on an element during stamping processes. Then, localized strain or necking strain is suggested to be a function of rho. Different stretch-bending tests with different tool radii, i.e., R3, R6, R10, and R50 are conducted for two automotive sheet metals, DP800 and AA6010, to identify their forming limits under combined stretch-bend loads. The calibrated necking limit curve of the AA6016 sheet is then employed in AutoForm R10 software to predict the necking and failure of a stamped panel. Agreement with the experimental observation of failure positions of the panel validates the usefulness of the proposed modeling approach in practice.

Automated summary

This study proposes a modeling approach to predict strain localization in sheet metal stamping processes in automotive engineering. The stretching-to-bending ratio, rho, is introduced to characterize the loading conditions, and localized strain is suggested to be a function of rho. Stretch-bending tests are conducted for two automotive sheet metals, DP800 and AA6010, with different tool radii to determine their forming limits. The proposed modeling approach is validated by predicting necking and failure positions of a stamped panel using the calibrated necking limit curve.