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A literature review of the springback of doubly curved developable sheet metal surfaces is presented in this paper. Related analyses, such as large curvature plastic bending and double curvature bending, are summarized here. Some well known results of the springback in sheet metal forming are also briefly discussed in order to thoroughly understand the problem. At the end of paper, a bibliography on the springback in sheet metal forming is provided as an appendix for readers' further interest and need of information.

A study is made of the factors affecting the formability of corners in the stamping of sheetmetal parts. The corners are modeled by toroidal shells. The factors considered are geometry, the toroidal radii A and B, friction factor μ, strain- hardening index n, and anisotropy ratio R. The analysis is based on a new differential equation approach, where formability is associated with singularities in the differential equations. The results presented in graphical form should prove useful for design. The difference between biaxial and plane strain conditions are made, and comparisons are made with some known experimental results and other theoretical results in the literature.

This paper describes some computer software developed at Michigan Technological University for the simulation of sheet metal forming which is a large-strain plastic deformation process. The approach taken is not the typical incremental solution approach, where one starts from the flat blank and steps are taken (hopefully) toward the final desired geometry, but a fast interactive one where the known surface geometry is mapped directly back to the flat blank. The strains are then calculated from the geometry change, and calculated strains are compared with experimental strains on a forming limit diagram (FLD) to determine formability. The theory of the deformation process is given in a number of earlier papers. This paper gives example results for several cases of axisymmetric and nonsymmetric geometries.