Sheet Metal Forming

The definition of the forming limit of sheet metals is based on the forming limit curve. This curve is used to predict the forming behaviour of sheet metals and provides a graphical representation of major and minor strains. These strains can be obtained by performing Nakajima or Marciniak tests in combination with an optical strain measurement system. In case of conventional deep drawing steels current methods provide reliable results in determining the onset of necking and thus the maximum of the major and minor strains. For high-strength steels these methods achieve to conservative values due to their non-pronounced necking development. The aim of this project is an objective and automatic classification of failure behaviour in sheet metals during forming processes to enable an accurate prediction of material behaviours.