Sheet Material Characterization with the In-Plane Torsion Test: Cyclic Loading, Grooved Specimen and Twin Bridge Specimen

The numerical analysis of springback in sheet metal forming is used to increase the accuracy of shape and the design of tools and processes. The more precise the material used for modeling is described, the more accurate the prediction ability of simulations is. For that reason, mixed isotropic-kinematic hardening models are used whose parameters are described by cyclic flow curves. The in-plane torsion test is used for the determination of cyclic flow curves. The optical strain measurement allows the simultaneous determination of cyclic flow curves with different pre-strain on a single sample. A modified twin bridge specimen is used to test anisotropic material behavior and a specimen with circular groove is used to characterize failure prediction under ideal shear load.