Novel In-Plane Torsion Specimen for the Characterization of Damage and Hardening – Curved Sheets and Components

In sheet metal forming, there are numerous methods for characterizing material properties that are required for reliable results in numerical simulation. Established methods like the tenisle test reach their limits when testing curved sheet metal - such as pipes - so that characterization is not possible, especially up to high strains. This project therefore aims to further develop the in-plane torsion test for testing curved sheets. To do this, evaluation methods for determining flow curves for rotationally and non-rotationally symmetrical specimens were developed and geometric and material influences on the results were analyzed numerically. In addition to the numerical considerations, experimental validations were carried out for rotationally symmetrical components, which showed good agreement between the flow curves determined and the reference tests on flat sheets. An analysis of the clamping showed that an inhomogeneous strain range occurs with the conventional clamping design. Adapting the clamping leeds to a homogeneous stress distribution, but is difficult to implement.