Modeling of the Hydroforming of Sheet Materials Clamped With Varying Blank Holding Loads

During hydroforming of sheet materials into axisymmetrical shells, varying the blank holding load causes a change in the draw-in condition of the flange, and hence deformation. By assuming the shell surface to be spherical and the infeeding material to be unstretched and uniformly distributed along the shell surface, a simple model is developed to describe the effect of blank holding load on the deformation of aluminum, brass and copper specimens. In this model, the size of the die shoulder radius is also considered; and the workhardening characteristic of sheet metal is linearized by the use of a suitable strain measure derived from the experimental curve. It is observed that the theoretical results compare well with experimental results.