Atsunobu Murata

Numerical Prediction of Springback Shape of Severely Bent Sheet Metal

In the sheet metal forming simulation, the shell element widely used is assumed as a plane stress state based on the Mindlin‐Reissner theory. Numerical prediction with the conventional shell element is not accurate when the bending radius is small compared to the sheet thickness. The main reason is because the strain and stress formulation of the conventional shell element does not fit the actual phenomenon. In order to predict precisely the springback of a bent sheet with a severe bend, a measurement method for through‐thickness strain has been proposed. The strain was formulated based on measurement results and calculation results from solid element. Through‐thickness stress distribution was formulated based on the equilibrium. The proposed shell element based on the formulations was newly introduced into the FEM code. The accuracy of this method’s prediction of the springback shape of two bent processes has been confirmed. As a result, it was found that the springback shape even in severe bending can b...