Verification of Finite Element Method Applied to Automobile Body Panels

Forming related problems of automobile body panels are analyzed in advance by several analytic methods, combining the geo metric or dynamic methods with the database we have stored. 3-dimensional finite element method seems to be an effective method to analyze shape fixability or surface distortion problems that occur on 3-dimensional complicated shape surfaces, that can not be analyzed by the usual methods.

In order to verify the utilities of FEM, we compared the actual stamped trunk lid outer draw panel with the FEM calculated results obtained by using explict FEM software J0H/DYNA3D.

The following results were obtained. The deformation behavior of the blank sheet and the fitting state when the blank sheet comes into contact with the punch during forming can be analyzed by FEM. But as for the amount of material flow and plastic strain distribution, the expected results could not be obtained because the blank sheet nodes were locked at the addendum shape area in calculation. This is thought to be due to modeling conditions such as punch radius, die radius and draw-bead shape, or forming conditions such as binder forces, boundary conditions which were a little different from the actual forming conditions. Therefore it is necessary to reinvestigate these conditions to make sure that FEM could be applied to actual die de signing.