Transient multi-field FEA model for predicting current density distribution when deforming sheet metal under a direct current

Previous investigations have been performed that involve developing new ways in which to deform a material while minimizing the energy required to do so. More recent research involves applying an electric current to the workpiece to achieve superplasticity. However, those investigations only utilized uniaxial workpieces and lack the ability to be used for more common geometries. The research presented herein, however, the effect is investigated under three-dimensional conditions so that the results could be projected to more realistic sheet metal geometries. A working finite element analysis (FEA) model has been developed to analyze these more complicated three-dimensional flow fields and will be presented as a part of this research. The model was used to solve for the temperature and current density distributions across the workpiece. The results from the FEA model are compared to results obtained from experimental tests. In the experimental setup, the two dome heights were separately tested under the same conditions that the FEA model simulated, however, only a temperature distribution was obtained here. The comparison of the FEA results and the experimental results related the temperature distribution to the current density distribution across the workpiece. From here, the individual effects of certain parameters on the distributions were found. The parameters included: duration of current, amount of current, electrode placement, and dome height geometry. The results showed that the current density distribution can be manipulated by varying the above parameters. This capability can be used to delay tearing/necking of a sheet metal workpiece under deformation.