Drawing, flanging and hemming of metallic thin sheets: A multi-step process

This study deals with the multi-step classical hemming process on samples with complex geometries and a pre-strain state linked to the forming of curved surface. The influence of taking the anisotropy and the Bauschinger effect into account on the roll-in and loads is studied. The design of a specific device was realised so as to compare the numerical results and the experimental values. The simulations show a certain relevance in the use of shell elements compared to solid elements despite their use restriction, and good correlation between the calculations and the tests. The roll-in differences and the level of stress reached are low at the end of pre-hemming and hemming, although a significant rotation of sections which are initially perpendicular to the mean fiber is observed during flanging.