Evaluation of formability enhancement of aluminum alloy sheet in electrohydraulic forming process with free-bulge die

Abstract

Electrohydraulic forming (EHF), a high-speed forming process, deforms a material by using high-pressure shockwaves in a fluid-filled chamber. When a material is deformed at speeds higher than 100 m/s, its formability can be improved due to the high-strain rate effect. This allows for the production of complex shapes, such as sharp edges. Therefore, in the present study, we confirm improvement in the formability of aluminum alloy 6061-T6 under high-strain rate condition by conducting EHF experiments. The strains of the deformed specimen are measured using a strain measurement apparatus, and they are compared with the values obtained from a quasi-static forming limit diagram. The comparison verified the improvement in formability, in that the material did not fracture even though the strain distribution of the material at high speeds was located higher than the quasi-static forming limit curve. In addition, we perform finite element analysis to observe the deformed material in detail. Finally, we compare the strain distributions obtained in the numerical simulation and the experiment to verify the reliability of the numerical model proposed herein.