A novel method of processing sheet metals: Electric-pulse triggered energetic materials forming

To improve the formability of sheet metals at room temperature and overcome the limitation of the upper limit of energy storage in electrohydraulic forming (EHF), a novel sheet metal forming is proposed: electric-pulse triggered energetic materials forming (ETEF). The power to deform a metal sheet originates from the electrical explosion of a metal wire in a liquid chamber and that releasing chemical energy from the energetic materials (EMs) being triggered. Equi-biaxial stretching tests of DP600 were carried out through ETEF with different weight ratios and changing grams under a low discharge voltage. The final profiles, strain and thickness distribution of the sheet were analyzed. The energetic materials with 10 wt.%Al/90 wt.%AP had an energy level of 3.04 kJ/g, and the bulging height of the deformed specimen was 34 mm, which was higher than the energy levels obtained under other testing conditions. Compared with that of the 7 kV specimen of the same bulging height (34 mm) obtained by EHF, the strain concentration region of the specimen processed under the 2 g/3 kV/10 wt.% Al/90 wt.%AP conditions widened by 52.5 %, and the maximum major strain and maximum thinning rates were lower by 10.6 % and 13.1 %, respectively. The dynamic deformation characteristics of the DP600 specimens during ETEF were presented for the first time by LS-DYNA. The values obtained for the DP600 sheet were as follows: maximum bulging height, 32 mm; maximum effective strain rate, 1521/s; and maximum speed, 258 m/s.