Development of nonlinear unfolding technique to find blank shape in deep drawing process

A new nonlinear inverse finite element method has been introduced to directly predict the blank shape and strain distribution on a given part that should be manufactured by deep drawing process. This method is helpful to determine draw ability of the part at the initial stage of design as well as obtaining the blank shape of the process. The approach deals with minimization of potential energy and large deformation relations with membrane elements. In this method the part has been unfolded properly on the flat sheet and treated as ۲D problem to reduce the computation time and the nonlinear stress-strain relationships of plastic material properties have been considered to increase the accuracy of the results. The finite element code has been prepared for the developed method and applied for a rectangular cup. The accuracy of the obtained blank shape and strain distribution of the considered part has been evaluated experimentally by drawing the rectangular cup. The measured thickness strains along the short and long sides of the rectangular cup, and its blank shape show good agreement with the results of the developed method.

Keywords:

Sheet metal forming , Inverse finite element method , Blank shape , nonlinear deformation