One of the important failure criteria of press operations in industry for forming simulations is
the Forming Limit Diagram (FLD). The complex loading effects on FLD, in particular the
localized necking phenomenon under stretch-bending condition, have not been fully
investigated and well understood. In practical sheet metal applications, the deformation is
invariably three dimensional with a combination of stretching and bending. For most sheet
materials under these complex loading processes used in industry, strong Bauschinger …

The Forming Limit Diagram (FLD) as developed by Keeler etc. has been widely used to
assess sheet metal failure during a variety of forming operations. Its theoretical and
empirical foundation is based on localized necking under biaxial loading for the sheet metal.
While the in-plane deformation is generally the dominant mode for most forming operations,
sheet metal bending is inevitably coupled to the deformation process, and the traditional
Forming Limit Diagram has to be modified to take into account the bending effect, especially …