An approximate solution for the hydrostatic bulging of circular diaphragms with draw-in allowed

Abstract

The hydroforming of sheet metal into shells can be found in many engineering applications, including the manufacture of containers and bursting discs and the investigation of sheet-metal formability and basic plasticity laws. As such, there is vast amount of literature on both the experimental and analytical aspects of this forming process. In these previous investigations, draw-in of the flange during forming has always been neglected: in the production line, however, complete elimination of flange movement is not always ensured, as is evident from the presence of wrinkles at the flanges of some hydroformed shells. Based on previous experimental observations and an earlier discussion on the effect of die shoulder radius, an approximate solution is developed in this paper to include the influence of slight draw-in during the hydroforming of copper sheets into axisymmetrical shells. The solution is further compared with experimental results; the latter, in general, agreeing with reasonable accuracy. Some limitations of the present solution are also discussed in this paper. © 1986.