Comparison of electromagnetically impacted and electromagnetic forming limit curves for AA5182-O aluminum alloy sheet

The strain paths of electromagnetic forming limit curve are usually limited due to the restricted design of coil, die or workpiece. The electromagnetically impacted Nakazima experiment was suggested to obtain the high speed forming limit curve of AA5182-O aluminum alloy sheet. The hemispherical punch was pushed by the drive plate with the Lorentz forces to impact the workpiece. The cross section method was used to determine the experimental limit strains of workpieces. The electromagnetic and mechanical fields were sequentially coupled for numerical simulation of the electromagnetically impacted Nakazima experiment, and the equivalent plastic strain increment ratios of the necking and safe zones were calculated to determine the simulated limit strains. A series of linear strain paths were attained to contain the uniaxial tension to biaxial tension states. The experimental and simulated forming limit curves showed good agreement to validate the electromagnetically impacted Nakazima experiment. The electromagnetically impacted forming limit curve was compared with the quasi-static and electromagnetic forming limit curves. Although the electromagnetically impacted forming limit curve is lower than the electromagnetic one, it is higher than the quasi-static one.