Abstract
We report the results of our experiments on and finite-element simulation of the electromagnetic free bulging of aluminum sheet metal. A single copper alloy plate is used in the experiments instead of a winding coil. The experiments are performed with a die of a 10mm circular hole with 2.0mm shoulder radius at 3.0kJ discharge energy. Then, both the formed height and thickness strain distribution of the sheet are measured. The height and strain distribution obtained by the FEM simulation are in close agreement with the experimental results. According to the simulation results, there is little movement of the sheet up to 3.3μs, which corresponds to the time of the maximum magnetic pressure. After 3.3μs, part of the sheet on the die shoulder causes a bending deformation because the sheet placed on the die hole begins to float, and then the sheet assumes the shape of a plastic hinge. In the time range from 5μs to 20μs, the sheet is always floating in parallel to the die hole at 190m/s, and then, a bending wave moves toward the center of the sheet at 330m/s, narrowing the floating region of the sheet. The sheet is deformed into a cone shape, and the bulging finishes at 27.5μs. Our simulation method is applicable to various materials.
