Improved FE simulation of tempered deep drawing in magnesium sheet materials through realistic modelling of their deformation capacity under process-relevant conditions

Magnesium alloys exhibit a high potential for lightweight construction in the automotive industry. However, elevated forming temperatures are required to increase formability. Numerical methods are used for the reliable design of forming processes. For a realistic numerical process mapping, an accurate modelling of the material and failure behaviour is required. To represent the plastic material behaviour, the magnesium sheet alloy AZ31 is characterised for process-relevant temperatures and the use of different flow laws is investigated in order to be able to depict the specific material behaviour. During deep drawing of magnesium components, failure phenomena can occur in the area of deep-drawn frames (see figure above). This failure behaviour cannot be recorded with the help of conventional methods, e.g. by using a forming limit curve (FLC), since the local stress states lies outside the range of validity of an FLC.

Therefore, a suitable stress-based failure model for various process temperatures is to be selected and parameterised in order to describe failure phenomena in the entire relevant stress range of sheet metal forming process. Such failure data for magnesium alloys is not yet available in the international research field. The calibration method of stress-based models is also crucial for the accuracy of the failure prediction. Therefore, a test set-up for failure characterisation magnesium under process-relevant temperatures will be developed based on a shear tensile specimen developed at IFUM. Finally, the potential of the methodology will be evaluated in comparison to the conventional use of an FLC in the simulation of a temperature-controlled deep drawing process with magnesium sheet material. The project results are intended to improve material modelling of magnesium sheet materials in forming simulations and to extend the limits of their processing in forming technology.