Development of a multistep inverse finite element method based on unfolding technique

Multistep inverse finite element analysis is developed to improve the accuracy of inverse simulation in deep drawing process. Since the direct numerical simulation of multistep drawing is very difficult and time consuming, it seems that the inverse approaches are very useful in initial design stages. They have the capability to determine optimum blank shape from the desired final part as well as thickness distribution on final part in a short time. Multistep inverse approach deals with finding initial guesses of nodal position on intermediate shapes and solving inverse equationsbetween two consecutive steps. In this paper a new mapping method is suggested to find initial solution of nodes on intermediate shapes and unfolding technique is applied in multistep inverse solution. The analysis results of a two stage drawing of circular cup are compared with experimental results to evaluate the effectiveness of the developed method. Comparison of one step and multistep results are also reported toverify the effect of multistep approach.

Keywords:

Sheet metal forming , Inverse FEM , Unfolding technique , Deformation theory of plasticity