Investigation of Biaxial Prestrain Influence on Bending-Under-Tension Springback

Springback notoriously depends on the strain-path history of the sheet material during forming. The bending-under-tension (BUT) test is used in this work for a discriminant characterization of springback in various conditions. In order to generate non-linear strain-paths, tensile prestrain is usually applied in the literature. In this work, an original biaxial prestrain device was designed and build. It allowed for the uniform prestrain of large samples of 500 mm diameter in DP600, up to 9.5% of strain. Subsequent samples for bending-under-tension were cut and tested at different combinations of tool radius and backforce. Classical models were used to describe the material’s behavior within finite element simulations of the BUT test. These experiments allowed for a discriminant comparison between the springback predictions of competing constitutive models.