Lehrstuhl für Fertigungstechnologie, Universität Erlangen-Nürnberg

Improvement of prediction of spot weld failure for ultra high strength steel grades



Datum: 28.03.2012


Author

  • Dr.-Ing. Martin Brandhuber

Reporter

  • Prof. Dr.-Ing. habil. M. Merklein
  • Prof. Dr.-Ing. habil. K. Steinhoff

To increase the prediction quality of spot weld failure a method to determine load capacity values for all body-in-white spot-welded joints was developed within this study. These can then later be used for structural simulation purposes. To characterize the load and failure behavior of spot-welded joints, a new specimen for quasi-static tests was developed. Afterwards, a limited number of different material pairings was analyzed at tensile tests under different loading directions to establish an experimental database. Based on these results and on metallographic analysis a calibration of correlation models representing all joints was carried out. Furthermore, it was intended to identify at the crash simulation stage where and when spot weld cracks could occur if ultra high strength steels are used. This has been done with use of calibrated substitute elements by compliance with conventional modeling techniques in finite element simulation. Finally, it could be concluded that the developed methods show a clear potential to increase prediction quality of the failure of and at spot welded joints.