FE-based springback prediction of sheet metal forming processes from lightweight materials considering the anisotropic hardening

Third party funded individual grant


Project Details

Project leader:
Prof. Dr.-Ing. Marion Merklein

Project members:
Peter Hetz

Contributing FAU Organisations:
Institute of Manufacturing Technology

Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Start date: 01/02/2019
End date: 31/01/2021


Abstract (technical / expert description):

Lightweight
construction allows a reduction in the weight of transportation means
and thus contributes to meeting the growing demands for lower emissions
and higher payloads. Therefore, especially lightweight materials, such
as magnesium and high-strength aluminium alloys, are of importance in
the automotive and aviation industry. Since magnesium and high-strength
aluminium alloys are limited formable at room temperature, they are
usually formed at elevated temperatures. Furthermore, previous
investigations have shown that these materials harden anisotropically
and exhibit a temperature-dependent as well as a tensile-compressive
asymmetric material behaviour. According to the current state of
research, new approaches are required to integrate the asymmetric
hardening behaviour of magnesium and high-strength aluminium alloys into
appropriate material models.


Within
this research project, selected magnesium and high-strength aluminium
alloys will be examined for anisotropic hardening and
tensile-compressive asymmetric material behaviour. Using isothermal cold
forming and warm forming tests between room temperature and 200°C,
relevant material parameters are determined to provide support points
for a material model.To
characterize the material parameters, uniaxial tensile and compression
tests as well as shear tensile and bulge tests are carried out.
According to present research, the relations between the microstructure
and the tension-compression asymmetry of high-strength aluminium alloys
are insufficiently identified. Hence, the uniaxial tensile and
compression tests are also metallographically analysed to detect the
change in the microstructure after tensile or compressive load. The
material behaviour is modelled on the basis of the experimentally
detected support points, by selecting suitable yield criteria,
identifying them and classifying them with regard to the mapping
accuracy. The identified material model is extended by the anisotropic
hardening as well as the temperature dependence and subsequently
evaluated by a reference model. The extended material model is
implemented in an industry-oriented simulation environment and then
verified by comparison with the experimentally determined flow curves.
For validation of the developed material model, the real spring back
angle of a deep drawn cross profile is investigated and compared with
the predicted spring back angle of a simulation model. Subsequently, the
extended material model is assessed with respect to the prediction
accuracy of the spring back behaviour.


Last updated on 2019-07-08 at 10:44