NUMERICAL ANALYSIS ON FABRICATION OF SPHERICAL SHELL BY NON-DIE EXPLOSIVE FORMING METHOD

摘要

In this paper, the deformation mechanism of a multi-cone structure which was filled with water and then was expanded into a spherical shell by a center located explosive was analyzed by numerical method. General speaking, the loading effects of an explosive dosage in explosive forming process can be distinguished by following two stages; (1) action of the shock wave, (2) loading of the gas bubble which travels at a much slower speed compared with the shock wave. Due to this explosive loading character, the deformation process of forming plate can be described as: (i)accelerating motion caused by the shock wave, (ii)free decreasing motion, at this moment, the action of shock wave was over and a cavitation area was formed between the moving plate and the water and (iii)re-aooelerated again by the high pressure gas bubble. The deformation which were caused by the shock wave and gas bubble were analyzed by ALE method. Then, the circularity-tendency of this multi-cone structure was demonstrated according to the analyzed results.